Sedimentary record of erg migration

Science.gov (United States)

Porter, M. L.

1986-06-01

The sedimentary record of erg (eolian sand sea) migration consists of an idealized threefold division of sand-sea facies sequences. The basal division, here termed the fore-erg, is composed of a hierarchy of eolian sand bodies contained within sediments of the flanking depositional environment. These sand bodies consist of eolian strata deposited by small dune complexes, zibars, and sand sheets. The fore-erg represents the downwind, leading edge of the erg and records the onset of eolian sedimentation. Basin subsidence coupled with erg migration places the medial division, termed the central erg, over the fore-erg strata. The central erg, represented by a thick accumulation of large-scale, cross-stratified sandstone, is the product of large draa complexes. Eolian influence on regional sedimentation patterns is greatest in the central erg, and most of the sand transported and deposited in the erg is contained within this region. Reduction in sand supply and continued erg migration will cover the central-erg deposits with a veneer of back-erg deposits. This upper division of the erg facies sequence resembles closely the fore-erg region. Similar types of eolian strata are present and organized in sand bodies encased in sediments of the upwind flanking depositional environment(s). Back-erg deposits may be thin due to limited eolian influence on sedimentation or incomplete erg migration, or they may be completely absent because of great susceptibility to postdepositional erosion. Tectonic, climatic, and eustatic influences on sand-sea deposition will produce distinctive variations or modifications of the idealized erg facies sequence. The resulting variants in the sedimentary record of erg migration are illustrated with ancient examples from western North America, Europe, southern Africa, and South America.

An Overview of the Soutpansberg Sedimentary and Volcanic Rocks

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J.W. Bristow

1986-11-01

Full Text Available Volcanic and sedimentary rocks occupy a faulted graben within the previously uplifted and eroded high-grade gneiss terrain of the Limpopo Mobile Belt. The rocks comprise the Soutpansberg Group and represent an important sequence of Proterozoic rocks. Their general geology and volcanology is summarised in this paper.

DOE workshop: Sedimentary systems, aqueous and organic geochemistry

International Nuclear Information System (INIS)

1993-07-01

A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries

DOE workshop: Sedimentary systems, aqueous and organic geochemistry

Energy Technology Data Exchange (ETDEWEB)

1993-07-01

A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries.

Lower Tertiary Sedimentary Turbidite Facies at the Chicontepec Basin, East-Central Mexico

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Santillán-Piña N.

2011-07-01

Full Text Available The study area comprises the northwestern portion of the Chicontepec Basin at southeastern San Luis Potosí and northeastern Hidalgo States. At the stratigraphy sequences of the Chicontepec Formation from Lower Paleocene in isolated outocrops, were herein interpreted two major sedimentary sub-environments into the fan model: the middle and the external sedimentary settings; the applied criteria for their identification were: (a lithostratigraphic (thickness, geometry and distribution; (b internal and external primary sedimentary structures, and (c intra-formational deformation structures. The sedimentary facies are composed of siliciclastic and calcareous particles sourced from the Sierra Madre Oriental, western; the Tuxpan paleo-island, eastern; and from the Teziutlan Massif, southern; the sediments were massively transported by slideing, slumping, flow debris and turbidity currents, then deposited as massive, tabular, lenticular and lobely in shape at the slope foot and on the sea marine floor.

Detrital zircon typology and U/Pb geochronology for the Miocene Ladrilleros-Juanchaco sedimentary sequence, Equatorial Pacific (Colombia): New constraints on provenance and paleogeography in northwestern South America

Energy Technology Data Exchange (ETDEWEB)

Osorio-Granada, E.; RESTREPO-MORENO, S.A.; MUÑOZ-VALENCIA, J.A.; TREJOS-TAMAYO, R.A.; PARDO-TRUJILLO, A.; BARBOSA-ESPITIA, A.A.

2017-11-01

Typology and internal texture analyses were performed on detrital zircons obtained from the Miocene sandstones of the Ladrilleros-Juanchaco sedimentary sequence (Colombia, Equatorial Pacific). This analysis was complemented with zircon U/Pb dating to identify typology-age associations as indicators of sediment provenance. Our results show that zircons with S and P dominant typologies have internal structures/zoning indicative of igneous, and potentially also metamorphic, origins. Morphometric results suggest limited transport from source areas. Both typology and U/Pb data point to the western Cordillera as the principal source of detrital materials for this sedimentary sequence. A paleogeographic reconstruction shows that, during the Late Miocene, significant portions of the western Cordillera were uplifted and actively eroding, thereby forming a fluvio-topographic barrier that prevented sediments from the central Cordillera reaching the Pacific basins. Exhumed Miocene plutons located along the axis of the western Cordillera may also have played a role as geomorphologically active massifs. This study demonstrates that typologic analysis on detrital zircon grains is a useful tool for establishing provenance and paleogeography in complex litho-tectonic areas where overlapping U/Pb signatures can lead to contradictory results.

Mineralizations of the Lavalleja Group (Uruguay), a Probable Neoproterozoic Volcano-sedimentary Sequence

International Nuclear Information System (INIS)

Sanchez Bettucci, L.; Oyhantcabal, P.; Loureiro, J.; Basei, M.; Ramos, V.; Preciozzi, F.; Basei, M.

2004-01-01

The Lavalleja Group is located in the southern extreme of the Dom Feliciano Belt, being tentatively correlated with the Porongos and Brusque Groups of Brazil. The basement of the Lavalleja Group is probably represented by granitic gneissic rocks of the Campanero Unit with ages, in the southern portion, ranging from 1.75 to 2.1 Ga (U-Pb in zircon). The Lavalleja Group is characterized by narrow bands of meta sedimentary and meta volcanic rocks and it is separated in three formations, namely (from base to top): Zanja del Tigre, Fuente del Puma and Minas. Outcrops assigned to the Minas Formation have been recently correlated with the Arroyo del Soldado Group. Only the Fuente del Puma formation hosts base metals, Au and Ag occurrences. The Fuente del Puma formation is divided into three informal units: sedimentary, volcanic and hornblenditic gabbros. The sedimentary unit is characterized by an important amount of carbonates. Syn collisional to pos tectonic granitic bodies (Carapé Complex) intrudes the Lavalleja Group and the Campanero Unit. Several mineralizations are located in the Fuente del Puma Formation, those associated to Arrospide, Ramallo-Reus, Chape, Valencia, La Oriental, Apolonia, Redondo Hill, La China and La Paloma mines are the most important. In addition, many occurrences of Cu-Zn-Pb were recognized in the region. The Cu-Zn-Pb mineralization includes massive sulfides with pyrite-chalcopyrite-sphalerite-galena-pyrrothyte, arsenopyrite-hematite into small bodies with lenticular shape. The host rock shows frequently hydrothermal alteration. The geochemistry and the geological features of the mineralizations suggest Besshi Massive Sulphide Zn-Cu-Pb and SEDEX Zn-Pb as most probably genetic models for the deposits related to the Neoproterozoic orogeny. Early mineralizations are syngenetic and were formed on the sea floor, although the main mineralizations are related to remobilization during syn- to late-metamorphic events and thrusting

Taphonomic expressions of sedimentary hiatuses: field observations on bioclastic concentrations and sequence anatomy in low, moderate and high subsidence settings

Science.gov (United States)

Kidwell, S. M.

1993-07-01

Field studies of post-Palaeozoic siliciclastic records reveal a strong concordance between different types of bioclastic concentrations and discontinuity surfaces within third-order sequences (≈ 1 My duration), supporting the use of taphonomic criteria in establishing the relative magnitudes of sedimentary hiatuses. Comparison of records across a spectrum of subsidence rates, however (from ≤ 10 m to > 1 km/My), shows that, along with appreciable changes in sequence anatomy, the nature of surface-mantling bioclastic concentrations also changes. The most significant surfaces (second- and third-order sequence boundaries, surfaces or intervals of maximum transgression, transgressive surfaces) tend to be either bare or mantled with taphonomically complex hiatal and lag concentrations. These were more consistently encountered in low subsidence than in moderate subsidence records. In high subsidence records, major surfaces were more often mantled by composite or event concentrations, if they were bioclastic at all. In all subsidence settings, comparatively minor surfaces (parasequence boundaries, bed set boundaries and bedding planes) were bare or mantled with relatively simple event and composite concentrations. Although all fossil assemblages are biased taphonomically to some degree, relative degrees of bias should almost certainly vary among discontinuities as a general rule, suggesting specific adjustments in sampling strategies for evolutionary studies.

Dichotomy Boundary at Aeolis Mensae, Mars: Fretted Terrain Developed in a Sedimentary Deposit

Science.gov (United States)

Irwin, R. P., III; Watters, T. R.; Howard, A. D.; Maxwell, T. A.; Craddock, R. A.

2003-03-01

Fretted terrain in Aeolis Mensae, Mars, developed in a sedimentary deposit. A thick, massive unit with a capping layer or duricrust overlies a more durable layered sequence. Wind, collapse, and minor fluvial activity contributed to degradation.

Ore-Forming Systems In Volcanogenic-Sedimentary Sequences By The Example Of Base Metal Deposits Of The Caucasus And East Pontic Metallotect

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Sergo KEKELIA

2004-06-01

Full Text Available By the example of Alpine volcanogenic base metal deposits of the central part of the AlpineHimalayan fold belt (East Pontic Metallotect and Caucasus, it has been demonstrated that their hydrothermal systems naturally emerge at various stages of active interaction of microplates-continental fragments of Eurasia and Gondwanaland. During the divergence stage, at the microplates-boundary zones within the marginal sea, hydrothermal-sedimentary Cu and polymetallic deposits have been formed; at the early convergence stage, within the paleo-island-arc systems, epigenetic Cu and in lesser extent, barite-polymetallic (Lesser Caucasus, and later both combined (hydrothermal-sedimentary and stockwork and epigenetic (mainly Cu- and Zn-containing deposits have been originated (East Pontic Metallotect. At the beginning of the collisional stage, in connection with antidrome volcanism within the back-arc volcanic structures, polyformational deposits (barite, barite-polymetallic, Cu, Au have been formed. This tendency persists during the whole collisional stage - in the within-plate and transplate Eocene volcanic depressions - mainly polymetallic deposits have been originated in which the increasing contents of Ag take place in comparison to Au. The authors share the opinion that the primarily- anomalous environments for Cu-Zn deposits can have been "specialized" basic and medium-acidic volcanics whereas for baritic and barite polymetallic deposits grey coloured and evaporitic sequences in the volcano-structure pedestals with buried highly mineralized brines seem to be most favorable.

Research on sequence stratigraphy of Shuixigou group, jurassic in Yili basin

International Nuclear Information System (INIS)

Li Shengfu; Wang Guo; Wei Anxin; Qi Junrang; Zhang Zhongwang

2006-01-01

The Shuixigou Group, Jurassic in Yili basin is a set of coal-bearing clastic formation formed under basically consistent tectonic stress and sedimentary environment. In the middle of the Group (Sangonghe Formation) abrupt changes appear in the lithology and the colour of rocks, and an abrupt turning in logging curve appears correspondingly. Using the point view of sequence stratigraphy, the authors analyse the above phenomenon in aspects of the chrono-stratigraphy, the lithology, the sedimentary system tract, the sedimentary rhythum, as well as the interpretation of logging curves, and suggest that a unconformity surface (or a sequence boundary) exists in the middle of the Group, and try make a re-division of sequence stratigraphy for the Shuixigou Group. (authors)

Quantitative Analogue Experimental Sequence Stratigraphy : Modelling landscape evolution and sequence stratigraphy of river-shelf sedimentary systems by quantitative analogue experiments

NARCIS (Netherlands)

Heijst, Maximiliaan Wilhelmus Ignatius Maria van

2000-01-01

This thesis reports a series of flume tank experiments that were conducted to model the stratigraphic evolution of river-delta systems. Chapter 1 introduces the river-delta sedimentary system that is subject of modelling. The chapter also includes an overview of previous research and the summary and

Tectonostratigraphic reconstruction Cretaceous volcano-sedimentary in the northwestern Andes: from extensional tectonics to arc accretion.

Science.gov (United States)

Zapata, S.; Patino, A. M.; Cardona, A.; Mejia, D.; Leon, S.; Jaramillo, J. S.; Valencia, V.; Parra, M.; Hincapie, S.

2014-12-01

Active continental margins characterized by continuous convergence experienced overimposed tectonic configurations that allowed the formation of volcanic arcs, back arc basins, transtensional divergent tectonics or the accretion of exotic volcanic terranes. Such record, particularly the extensional phases, can be partially destroyed and obscure by multiple deformational events, the accretion of exotic terranes and strike slip fragmentation along the margin. The tectonic evolution of the northern Andes during the Mesozoic is the result of post Pangea extension followed by the installation of a long-lived Jurassic volcanic arc (209 - 136 ma) that apparently stops between 136 Ma and 110 Ma. The Quebradagrande Complex has been define as a single Lower Cretaceous volcano-sedimentary unit exposed in the western flank of the Central Cordillera of the Colombian Andes that growth after the Late Jurassic to Early Cretaceous magmatic hiatus. The origin of this unit have been related either to an oceanic volcanic arc or a marginal basin environment. The existence of such contrasting models reflect the regional perspective followed in published studies and the paucity of detail analysis of the volcano-sedimentary sequences.We integrate multiple approaches including structural mapping, stratigraphy, geochemistry, U-Pb provenance and geochronology to improve the understanding of this unit and track the earlier phases of accumulation that are mask on the overimposed tectonic history. Our preliminary results suggest the existence of different volcano-sedimentary units that accumulated between 100 Ma and 82 Ma.The older Lower Cretaceous sequences was deposited over Triassic metamorphic continental crust and include a upward basin deepening record characterized by thick fan delta conglomerates, followed by distal turbidites and a syn-sedimentary volcanic record at 100 ma. The other sequence include a 85 - 82 Ma fringing arc that was also formed close to the continental margin or

Fluvial systems and their sedimentary models

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Dragomir Skabeme

1995-12-01

Full Text Available The Slovenian géomorphologie and sedimentologie terminology for fluvial depositional environments is not established yet. Therefore a classification and the proposal for Slovenian names of fluvial sedimentary and erosional forms and influences controlling them are discussed. Attention is given to the problems of recognition of sedimentary environments in sedimentary rocks, and to fluvial sedimentary models.

Discussion on the origin of sedimentary rock resistivity

International Nuclear Information System (INIS)

Dong Gangjian

2012-01-01

Conduction current way of sedimentary rock sedimentary rock is caused by the internal structure of sedimentary rock sedimentary rock pore resistance depends on the salinity of pore water and clay content and distribution. Resistivity of sedimentary rock sedimentary rock major factor in mineral composition, water resistance, oil resistance. and sedimentary structures. In practice, we should give full attention to the difference between lithology and physical properties. (author)

Favorability for uranium in tertiary sedimentary rocks, southwestern Montana

International Nuclear Information System (INIS)

Wopat, M.A.; Curry, W.E.; Robins, J.W.; Marjaniemi, D.K.

1977-10-01

Tertiary sedimentary rocks in the basins of southwestern Montana were studied to determine their favorability for potential uranium resources. Uranium in the Tertiary sedimentary rocks was probably derived from the Boulder batholith and from silicic volcanic material. The batholith contains numerous uranium occurrences and is the most favorable plutonic source for uranium in the study area. Subjective favorability categories of good, moderate, and poor, based on the number and type of favorable criteria present, were used to classify the rock sequences studied. Rocks judged to have good favorability for uranium deposits are (1) Eocene and Oligocene strata and undifferentiated Tertiary rocks in the western Three Forks basin and (2) Oligocene rocks in the Helena basin. Rocks having moderate favorability consist of (1) Eocene and Oligocene strata in the Jefferson River, Beaverhead River, and lower Ruby River basins, (2) Oligocene rocks in the Townsend and Clarkston basins, (3) Miocene and Pliocene rocks in the Upper Ruby River basin, and (4) all Tertiary sedimentary formations in the eastern Three Forks basin, and in the Grasshopper Creek, Horse Prairie, Medicine Lodge Creek, Big Sheep Creek, Deer Lodge, Big Hole River, and Bull Creek basins. The following have poor favorability: (1) the Beaverhead Conglomerate in the Red Rock and Centennial basins, (2) Eocene and Oligocene rocks in the Upper Ruby River basin, (3) Miocene and Pliocene rocks in the Townsend, Clarkston, Smith River, and Divide Creek basins, (4) Miocene through Pleistocene rocks in the Jefferson River, Beaverhead River, and Lower Ruby River basins, and (5) all Tertiary sedimentary rocks in the Boulder River, Sage Creek, Muddy Creek, Madison River, Flint Creek, Gold Creek, and Bitterroot basins

Lavalleja group (Uruguay) a neoproterozoic metavolcanic-sedimentary sequence: ore deposits

International Nuclear Information System (INIS)

Sanchez Bettucci, L.; Preciozzi, F.; Ramos, V.

2003-01-01

The Lavalleja meta volcano-sedimentary Group, exposed along the Dom Feliciano Belt, is located in the southeast of Uruguay and formed by meta gabbros, basic and acid meta volcanic rocks. It was developed during late Proterozoic-Early Paleozoic Brasiliano orogeny. Based on the geochemical signature, Sánchez-Bettucci et al. (2001) suggested a back-arc basin tectonic setting. The metamorphic grade increases to the southeast, ranging from very low grade to lower green schist facies in the Minas formation, to lower amphibolite facies in the Fuente del Puma and Zanja del Tigre Formations (Sánchez-Bettucci et al., 2001). The metamorphic mineral assemblages correspond to a low-pressure regional metamorphism associated with a high thermal gradient (Sánchez-Bettucci et al., 2001).A compressive deformational event, that probably corresponds to the basin closure of the Lavalleja Group during a continental collision was recognized. The petrology, geochemistry, metamorphism grade, and tectonic setting are consistent with a back-arc basin as suggested by Sánchez-Bettucci et al. (2001)

Provenance of zircon of the lowermost sedimentary cover, Estonia, East-European Craton

Directory of Open Access Journals (Sweden)

Konsa, M.

1999-12-01

Cambrian sequence, zircons resembling those of local basement sources are very rare or absent. Obviously, basal Vendian/Cambrian sedimentary rocks sealed off the basement as a source of zircon. Therefore a distant source, probably outside the Svecofennian Domain, could be supposed for the bulk clastic minerals and zircons of the upperpart of the Vendian and the lower part of the Cambrian. Probably, studies of isotopic ages of different typological varieties of zircons, both of obviously local and distant origin, could provide new information on respective source rock ages and areas, and on the general palaeogeographic pattern of the Vendian and Cambrian epicratonic sedimentary basins of the East-European Craton.

REGIONAL OUTCROPS WITH DIDACTIC INTEREST AND SEDIMENTARY FACIES ASSOCIATION OF THE ITARARÉ GROUP AT SÃO PAULO (BRAZIL

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Sérgio Bergamaschi

2016-03-01

Full Text Available The main objective of this work is to locate and identify the outcrops considered iconic and valuable as references, not only from the point of view of Cultural or Didactic Tourism, but also in paleoenvironmental reconstruction studies, based on the lithologies that comprise the Itararé Group, in the State of São Paulo, Brazil. This work also intends to relate these sites to outcrops of sedimentary facies, in an area located at south of Itu and Porto Feliz, and north of Sorocaba. The Itararé Group lies within the Paraná Basin (Paleozoic, and is composed by sedimentary sequences associated with the record of the Permo-Carboniferous glaciation event that occurred in the Gondwana supercontinent. This work is based on observations of outcrops in a macro- and mesoscopic scale, considering the characterization of external and internal aspects of the layer, the stratigraphic sequence in the outcrop, and the continuity of the layers within the mapped area. The study area has outcrops where the evidences of glaciomarine deposits predominate. Sedimentary sequences deposited in a subaquatic low-energy environment, as well as episodic deposits, in which relatively more energetic phases alternated with low hydrodynamic conditions are well-developed in the study area. There are also fluvio-deltaic environmental occurrences related to sea level oscillations linked with glacier advances and receding.

Geochronology of the Jequie-Itabuna granulitic belt and of the Contendas-Mirante volcano-sedimentary belt

International Nuclear Information System (INIS)

Marinho, Moacyr M.; Barbosa, Johildo S.F.; Sabate, Pierre

1995-01-01

The Jequie-Itabuna Granulitic Belt is divided here into the Jequie-Mutuipe-Maracas Domain and the Atlantic Coast Domain. The paper analyzes the geochronological data from the Jequie-Mutuipe-Maracas Domain in two parts: plutonic rocks equilibrated in granulite facies, including the charno-enderbitic rocks from the Laje-Mutuipe region and the charnockitic rocks from the Maracas region; and ortho- and paraderived rocks metamorphosed in granulite facies, with the data obtained from rocks collected at the Jequie quarry and from homogeneous rocks collected at the western outskirts of the Jequirica town. The available geochronological data for the Atlantic Coast Domain is discussed, and due to the lack of petrologic control of the analyzed rocks, the geological significance of the ages between 2.0 and 2.3 is obtained in several line regressions. The paper identifies the following domains within the Contendas-Mirante volcano-sedimentary belt: the the basement dones, the volcano-sedimentary sequence and the intrusive rocks. The basement domes is the domain of the ancient gray gneisses (ca 3.4 Ga), to TTG (tonalite-trondhjemite-granodiorite) terrains and among the different massifs that crop out in the SE sector of the volcano-sedimentary belt, those of Sete Voltas and Boa Vista/Mata Verde have geochronological data available. The volcano-sedimentary sequence is divided into a lower, a middle and an upper unit and its available isotopic data are analyzed. The item referent to the intrusive rocks deals with the following plutons: The Lagoa Morro da Velha granitoid, the Pe da Serra granite, the Rio Jacare sill and the Transamazonian granites. 31 figs., 5 tabs

CSPG - SEPM joint convention : Program with abstracts - Sedimentary events and hydrocarbon systems

International Nuclear Information System (INIS)

Beauchamp, B.

1997-01-01

This joint conference of the Canadian Society of Petroleum Geologists (CSPG) and the Society for Sedimentary Geology (SEPM) was held in Calgary, to encourage collaboration between the petroleum resource industry and academia. Well over 150 papers were presented in various special sessions. The principal topics of discussion included examination, investigation and assessment of the geology, geophysics, geochemistry and the resource potential of sedimentary basins in Canada and around the world. In the course of the presentations the depositional, tectonic and diagenetic histories of various formations, augmented with interpretations of the origin and evolution of the basins were reviewed. The new interpretations were made possible by the new concepts and models of sedimentary geoscience that were born in the creative cauldron of collaboration that exists between industry, government institutions and the universities. The widespread use of modern sequence stratigraphy was used as an example of how scientific and engineering synergy evolved over time to shed new light on the nature of the stratigraphic record. Environmental issues regarding the petroleum industry also received much attention. This volume contains the complete conference program listing, a list of the sponsors and exhibitors, and provides brief abstracts of all papers presented at the conference

Study of the argillaceous fraction of sedimentary sequences of Meuse and Gard. Reconstitution of the diagenetic history and of the physico-chemical characteristics of the targets. Mineralogical, geochemical and isotopic aspects

International Nuclear Information System (INIS)

Rousset, D.

2002-01-01

Very low permeable argillaceous rocks like Callovo-Oxfordian clay-stones or Vraconian siltstones were chosen to host a research laboratory built to determine the physico-chemical properties of the host formations for a potential underground disposal of radioactive waste. Knowledge and understanding of post-sedimentary modifications are of prime importance for definition of these properties; evaluation and quantification of the post-sedimentary changes represent the aim of this study, focused specifically on the clay material of the sequences. Samples were taken from two drillings (HTM102 and MAR501). In the HTM102 core samples, illite and mixed-layers illite/smectite are the dominant clay components of most clay fractions. Systematic SEM and TEM observations and isotopic K-Ar and Rb-Sr analyses pointed to diagenetic neo-formations of carbonates (calcite, dolomite) and clays. For instance, veils and laths of authigenic clay particles around old detrital ones can distinctly be observed. The epoch, duration and extent of the diagenetic activity(ies) are difficult to evaluate because of an overall detrital contribution even in the finest granulometric fractions. However; analysis of a bentonite layer in the sequence provides a diagenetic reference for the authigenic clay material. Correlation between relative sea level and authigenesis of smectite-rich mineral has been outlined. Chemistry of diagenetic fluids also seems to be reliable with sea level variations. These observations argue in favour of diagenetic activities limited in restricted rock volumes. The case study of MAR501 is close to the HTM102 one: smectite-rich illite/smectite mixed-layers represent the major component of the clay fraction and K-Ar values argue ire the sense of a mixing between detrital and younger clay populations. Diagenetic glauconites in the sequence yield are age close to 93,7 ±0,3 Ma for Vraconian level, in agreement with stratigraphical data. The case study of a clay-filled fault

Monitoring the sedimentary carbon in an artificially disturbed deep-sea sedimentary environment

Digital Repository Service at National Institute of Oceanography (India)

Nath, B.N.; Khadge, N.H.; Nabar, S.; Raghukumar, C.; Ingole, B.S.; Valsangkar, A.B.; Sharma, R.; Srinivas, K.

1 Author version: Environ. Monit. Assess., vol.184; 2012; 2829-2844 Monitoring the sedimentary carbon in an artificially disturbed deep-sea sedimentary environment B. Nagender Nath * , N.H. Khadge, Sapana Nabar, C. Raghu Kumar, B.S. Ingole... community two years after an artificial rapid deposition event. Publication of Seto Marine Biological Laboratory, 39(1), 17-27. Gage, J.D. (1978). Animals in deep-sea sediments. Proceedings of Royal Society of Edinburgh, 768, 77-93. Gage, J.D., & Tyler...

Shell Bed Identification of Kaliwangu Formation and its Sedimentary Cycle Significance, Sumedang, West Java

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Aswan Aswan

2014-07-01

Full Text Available DOI: 10.17014/ijog.v8i1.151Kaliwangu Formation cropping out around Sumedang area contains mollusk fossils dominated by gastropods and bivalves. In terms of sequence stratigraphy, each sedimentary cycle generally consists of four shell bed types: Early Transgressive Systems Tract (Early TST deposited above an erosional surface or sequence boundary, that is characterized by shell disarticulation, trace fossils, gravelly content, no fossil orientation direction, and concretion at the bottom; Late Transgressive Systems Tract (Late TST identified by articulated (conjoined specimen in its life position, that shows a low level abration and fragmentation, adult specimen with complete shells, and variation of taxa; Early Highstand Systems Tract (Early HST characterized by adult taxa that was found locally in their life position with individual articulation, juvenile specimens frequently occured; Late Highstand Systems Tract (Late HST determined as multiple-event concentrations, disarticulated shell domination, and some carbon or amber intercalation indicating terrestrial influence. Shell bed identification done on this rock unit identified nineteen sedimentary cycles.

Reservoir characteristics of coal-shale sedimentary sequence in coal-bearing strata and their implications for the accumulation of unconventional gas

Science.gov (United States)

Wang, Yang; Zhu, Yanming; Liu, Yu; Chen, Shangbin

2018-04-01

Shale gas and coalbed methane (CBM) are both considered unconventional natural gas and are becoming increasingly important energy resources. In coal-bearing strata, coal and shale are vertically adjacent as coal and shale are continuously deposited. Research on the reservoir characteristics of coal-shale sedimentary sequences is important for CBM and coal-bearing shale gas exploration. In this study, a total of 71 samples were collected, including coal samples (total organic carbon (TOC) content >40%), carbonaceous shale samples (TOC content: 6%-10%), and shale samples (TOC content TOC content. Clay and quartz also have a great effect on the porosity of shale samples. According to the FE-SEM image technique, nanoscale pores in the organic matter of coal samples are much more developed compared with shale samples. For shales with low TOC, inorganic minerals provide more pores than organic matter. In addition, TOC content has a positive relationship with methane adsorption capacity, and the adsorption capacity of coal samples is more sensitive than the shale samples to temperature.

Determining the Accuracy of Paleomagnetic Remanence and High-Resolution Chronostratigraphy for Sedimentary Rocks using Rock Magnetics

Science.gov (United States)

Kodama, K. P.

2017-12-01

The talk will consider two broad topics in rock magnetism and paleomagnetism: the accuracy of paleomagnetic remanence and the use of rock magnetics to measure geologic time in sedimentary sequences. The accuracy of the inclination recorded by sedimentary rocks is crucial to paleogeographic reconstructions. Laboratory compaction experiments show that inclination shallows on the order of 10˚-15˚. Corrections to the inclination can be made using the effects of compaction on the directional distribution of secular variation recorded by sediments or the anisotropy of the magnetic grains carrying the ancient remanence. A summary of all the compaction correction studies as of 2012 shows that 85% of sedimentary rocks studied have enjoyed some amount of inclination shallowing. Future work should also consider the effect of grain-scale strain on paleomagnetic remanence. High resolution chronostratigraphy can be assigned to a sedimentary sequence using rock magnetics to detect astronomically-forced climate cycles. The power of the technique is relatively quick, non-destructive measurements, the objective identification of the cycles compared to facies interpretations, and the sensitivity of rock magnetics to subtle changes in sedimentary source. An example of this technique comes from using rock magnetics to identify astronomically-forced climate cycles in three globally distributed occurrences of the Shuram carbon isotope excursion. The Shuram excursion may record the oxidation of the world ocean in the Ediacaran, just before the Cambrian explosion of metazoans. Using rock magnetic cyclostratigraphy, the excursion is shown to have the same duration (8-9 Myr) in southern California, south China and south Australia. Magnetostratigraphy of the rocks carrying the excursion in California and Australia shows a reversed to normal geomagnetic field polarity transition at the excursion's nadir, thus supporting the synchroneity of the excursion globally. Both results point to a

Sedimentary Petrology: from Sorby to the globalization of Sedimentary Geology; La Petrologia Sedimentaria: desde Sorby a la globalizacion de la Geologia Sedimentaria

Energy Technology Data Exchange (ETDEWEB)

Alonso-Zarza, A M

2013-02-01

We describe here the most important milestones and contributions to Sedimentary Petrology compared to other geological disciplines. We define the main aim of our study and the scientific and economic interests involved in Sedimentary Petrology. The body of the paper focuses upon the historical development of this discipline from Henry Sorby's initial work until the present day. The major milestones in its history include: 1) initial descriptive works; 2) experimental studies; 3) the establishment of the different classifications of sedimentary rocks; 4) studies into facies and sedimentary environments; 5) advances in the study of diagenetic processes and their role in hydrocarbon prospection; and 6) the development of Sedimentary Geochemistry. Relationships and coincidences with Sedimentology are discussed. We go on to look at the advances that have taken place over the last 30 years, in which the study of sedimentary rocks is necessarily included in the wider field of Sedimentary Geology as a logical result of the proposal of global models of a changing Earth in which Sedimentary Geology plays a significant part. Finally we mention the notable contributions of Spanish sedimentary petrologists to this whole field of science. (Author) 120 refs.

Sedimentary Petrology: from Sorby to the globalization of Sedimentary Geology; La Petrologia Sedimentaria: desde Sorby a la globalizacion de la Geologia Sedimentaria

Energy Technology Data Exchange (ETDEWEB)

Alonso-Zarza, A. M.

2013-02-01

We describe here the most important milestones and contributions to Sedimentary Petrology compared to other geological disciplines. We define the main aim of our study and the scientific and economic interests involved in Sedimentary Petrology. The body of the paper focuses upon the historical development of this discipline from Henry Sorby's initial work until the present day. The major milestones in its history include: 1) initial descriptive works; 2) experimental studies; 3) the establishment of the different classifications of sedimentary rocks; 4) studies into facies and sedimentary environments; 5) advances in the study of diagenetic processes and their role in hydrocarbon prospection; and 6) the development of Sedimentary Geochemistry. Relationships and coincidences with Sedimentology are discussed. We go on to look at the advances that have taken place over the last 30 years, in which the study of sedimentary rocks is necessarily included in the wider field of Sedimentary Geology as a logical result of the proposal of global models of a changing Earth in which Sedimentary Geology plays a significant part. Finally we mention the notable contributions of Spanish sedimentary petrologists to this whole field of science. (Author) 120 refs.

Cu-Ag Besshi type volcanogenic massive sulfide mineralization in the Late Cretaceous volcano- sedimentary sequence: the case of Garmabe Paein deposit, southeast of Shahrood

Directory of Open Access Journals (Sweden)

Majid Tashi

2017-07-01

Full Text Available Introduction Iran hosts numerous types of Volcanogenic massive sulfide (VMS deposits that occur within different tectonic assemblages and have formed at discrete time periods (Mousivand et al. 2008. The Sabzevar zone hosts several VMS deposits including the Nudeh Cu-Ag deposit (Maghfouri, 2012 and some deposits in the Kharturan area (Tashi et al., 2014, and the Kharturan area locates in the Sabzevar subzone of the Central East Iranian Microcontinent. The Sabzevar subzone mainly involves Mesozoic and Cenozoic rock unites. The Late Cretaceous ophiolite mellanges and volcano-sedimentary sequences have high extension in the Subzone. Based on Rossetti (Rossetti et al. 2010, the Cretaceous rock units were formed in a back-arc setting due to subduction of the Neo-Tethyan oceanic crust beneath the Iranian plate. The exposed rock units of the Kharturan area from bottom to top are dominated by Early Cretaceous, orbitolina-bearing massive limestone, dacitic-andesitic volcanics and related volcaniclastic rocks٫ chert and radiolarite and Late Cretaceous globotrunkana- bearing limestone, paleocene polygenic conglomerate consisting of the Cretaceous volcanics and limestone pebbles (equal to the Kerman conglomerate, and Pliocene weakly-cemented polygenic conglomerate horizon. The Garmabe Paein copper-silver deposit and the Asbkeshan deposit and a few occurrences, are located at 290 km southeast of Shahrood and they have occurred within the Upper Cretaceous volcano-sedimentary sequence in the Sabzevar subzone. The aim of this study is to discuss the genesis of the Garmabe Paein deposit based on geological, textural and structural, mineralogical and geochemical evidence. Materials and methods A field study and sampling was performed during the year 2013. During the field observations, 94 rock samples were collected from the study area, and 45 thin sections were prepared and studied using a polarizing microscope. Also, 5 samples for the XRD method, 21 samples for

Measurement of unsaturated hydraulic properties and evaluation of property-transfer models for deep sedimentary interbeds, Idaho National Laboratory, Idaho

Science.gov (United States)

Perkins, Kimberlie; Johnson, Brittany D.; Mirus, Benjamin B.

2014-01-01

Operations at the Idaho National Laboratory (INL) have the potential to contaminate the underlying Eastern Snake River Plain (ESRP) aquifer. Methods to quantitatively characterize unsaturated flow and recharge to the ESRP aquifer are needed to inform water-resources management decisions at INL. In particular, hydraulic properties are needed to parameterize distributed hydrologic models of unsaturated flow and transport at INL, but these properties are often difficult and costly to obtain for large areas. The unsaturated zone overlying the ESRP aquifer consists of alternating sequences of thick fractured volcanic rocks that can rapidly transmit water flow and thinner sedimentary interbeds that transmit water much more slowly. Consequently, the sedimentary interbeds are of considerable interest because they primarily restrict the vertical movement of water through the unsaturated zone. Previous efforts by the U.S. Geological Survey (USGS) have included extensive laboratory characterization of the sedimentary interbeds and regression analyses to develop property-transfer models, which relate readily available physical properties of the sedimentary interbeds (bulk density, median particle diameter, and uniformity coefficient) to water retention and unsaturated hydraulic conductivity curves.

A dual-biomarker approach for quantification of changes in relative humidity from sedimentary lipid D∕H ratios

Directory of Open Access Journals (Sweden)

O. Rach

2017-07-01

Full Text Available Past climatic change can be reconstructed from sedimentary archives by a number of proxies. However, few methods exist to directly estimate hydrological changes and even fewer result in quantitative data, impeding our understanding of the timing, magnitude and mechanisms of hydrological changes. Here we present a novel approach based on δ2H values of sedimentary lipid biomarkers in combination with plant physiological modeling to extract quantitative information on past changes in relative humidity. Our initial application to an annually laminated lacustrine sediment sequence from western Europe deposited during the Younger Dryas cold period revealed relative humidity changes of up to 15 % over sub-centennial timescales, leading to major ecosystem changes, in agreement with palynological data from the region. We show that by combining organic geochemical methods and mechanistic plant physiological models on well characterized lacustrine archives it is possible to extract quantitative ecohydrological parameters from sedimentary lipid biomarker δ2H data.

Gravimetric survey and modeling of the basement morphology in the sedimentary thickness characterization, NE portion of Paraná Sedimentary Basin - Brazil

Directory of Open Access Journals (Sweden)

Maximilian Fries

2017-05-01

Full Text Available ABSTRACT: The northeast portion of the Paraná Sedimentary Basin is distinguished by structural highs as the known Pitanga Dome, an uplifted structure identified in the last century. It represents a geological and evolutionary evidence of the Paraná Sedimentary Basin and has undergone inspired studies and intense exploration surveys. This study consists of a gravimetric survey in the Pitanga Dome area, State of São Paulo, Brazil. The Bouguer gravity anomalies have been identified and related to the structural high, sedimentary thickness, and the basement morphology. Processing and enhancement techniques were used for forward modeling based on previous studies. The three models from profiles sectioning the dome have a sedimentary thickness varying from 200 to 1.250 meters. The adopted methodology has provided important results determining that the Pitanga Dome can be understood through rational 3D visualization. The area can be interpreted as an undulating basement with thinning of sedimentary rocks related to deep features (structures in the crust/mantle limit (Moho uplift. This characteristic is confirmed by the sedimentary layer thickening present throughout the surrounding area. The results also offer important insights and support for further studies concerning the genesis and evolution of this and other uplifted structures of the Paraná Sedimentary Basin.

Sedimentary history and economic geology of San Juan Basin, New Mexico and Colorado

International Nuclear Information System (INIS)

Peterson, J.A.; LeLeit, A.J.; Spencer, C.W.; Ullrich, R.A.

1981-01-01

The San Juan Basin contains up to 15,000 ft of sedimentary rocks ranging in age from Cambrian to Recent. The earliest development of the area as a sedimentary basin or trough apparently took place in Pennsylvanian time, and the basin was maintained, with changing rates of subsidence and filling, through the remainder of geologic time. During the Early Paleozoic, sedimentation was dominated by marine transgressions across the northwestern flank of the regional Transcontinental Arch. The Late Paleozoic history was strongly influenced by tectonism related to development of the Ancestral Rocky Mountains Uplifts and associated downwarping. The Early Mesozoic is characterized by fluvial and eolian environments, interrupted periodically by thin marine transgressive deposits of nearshore redbeds. The final Mesozoic event was the widespread Late Cretaceous marine transgression which deposited a thick cyclic sequence of marine gray shale and sandstone, with interbedded coal. Late Tertiary regional uplift and resulting volcanism were accompanied by a regional dissection of the area by stream systems that evolved into the present drainage pattern of superposed streams. The sedimentary history is directly related to the occurrence of economic deposits in the basin. Major reserves of petroleum and gas are in Cretaceous and Pennsylvanian rocks, coal in Cretaceous, and uranium in Jurassic and Cretaceous. Abstract only

Isolation of Geobacter species from diverse sedimentary environments

Science.gov (United States)

Coaxes, J.D.; Phillips, E.J.P.; Lonergan, D.J.; Jenter, H.; Lovley, D.R.

1996-01-01

In an attempt to better understand the microorganisms responsible for Fe(III) reduction in sedimentary environments, Fe(III)-reducing microorganisms were enriched for and isolated from freshwater aquatic sediments, a pristine deep aquifer, and a petroleum-contaminated shallow aquifer. Enrichments were initiated with acetate or toluene as the electron donor and Fe(III) as the electron acceptor. Isolations were made with acetate or benzoate. Five new strains which could obtain energy for growth by dissimilatory Fe(III) reduction were isolated. All five isolates are gram- negative strict anaerobes which grow with acetate as the electron donor and Fe(III) as the electron acceptor. Analysis of the 16S rRNA sequence of the isolated organisms demonstrated that they all belonged to the genus Geobacter in the delta subdivision of the Proteobacteria. Unlike the type strain, Geobacter metallireducens, three of the five isolates could use H2 as an electron donor fur Fe(III) reduction. The deep subsurface isolate is the first Fe(III) reducer shown to completely oxidize lactate to carbon dioxide, while one of the freshwater sediment isolates is only the second Fe(III) reducer known that can oxidize toluene. The isolation of these organisms demonstrates that Geobacter species are widely distributed in a diversity of sedimentary environments in which Fe(III) reduction is an important process.

Sequence stratigraphy, sedimentary systems and petroleum plays in a low-accommodation basin: Middle to upper members of the Lower Jurassic Sangonghe Formation, Central Junggar Basin, Northwestern China

Science.gov (United States)

Feng, Youliang; Jiang, Shu; Wang, Chunfang

2015-06-01

The Lower Jurassic Junggar Basin is a low-accommodation basin in northwestern China. Because of low subsidence rates and a warm, wet climate, deposits of the Central subbasin of the Junggar Basin formed from fluvial, deltaic, shallow lake facies. Sequence stratigraphy and sedimentary systems of the Lower Jurassic members of the Sangonghe Formation (J1s) were evaluated by observing cores, interpreting wireline logs and examining seismic profiles. Two third-order sequences were recognized in the strata. The distribution of the sedimentary systems in the systems tracts shows that tectonic movement, paleorelief, paleoclimate and changes in lake level controlled the architecture of individual sequences. During the development of the lowstand systems tract (LST), the intense structural movement of the basin resulted in a significant fall in the water level in the lake, accompanied by rapid accommodation decrease. Braided rivers and their deltaic systems were also developed in the Central Junggar Basin. Sediments carried by braided rivers were deposited on upward slopes of the paleorelief, and braid-delta fronts were deposited on downward slopes. During the transgressive systems tract (TST), the tectonic movement of the basin was quiescent and the climate was warm and humid. Lake levels rose and accommodation increased quickly, shoal lines moved landward, and shore- to shallow-lake deposits, sublacustrine fans and deep-lake facies were deposited in shallow- to deep-lake environments. During the highstand systems tract (HST), the accommodation no longer increased but sediment supply continued, far exceeding accommodation. HST deposits slowly formed in shallow-lake to meandering river delta-front environments. Relatively low rates of structural subsidence and low accommodation resulted in coarse-grained successions that were fining upward. Deposits were controlled by structural movement and paleorelief within the LST to TST deposits in the Central subbasin. Fine- to medium

Geochronology of La Tinta Upper Proterozoic sedimentary rocks, Argentina

International Nuclear Information System (INIS)

Cingolani, C.A.; Bonhomme, M.G.

1982-01-01

Olavarria-Sierras Bayas, Barker-San Manuel and Balcarce-Mar del Plata fine-grained sedimentary rocks from La Tinta Formation, the pre-Cenozoic cover of the Tandilia region, were studied using the Rb-Sr and K-Ar geochronology. The mineralogical study of the fine fraction has shown that only the Olavarria-Sierras Bayas area presents suitable material comprising typical sedimentary clays, affected only by diagenetic processes. Two Rb-Sr isochrons were obtained from Olavarria-Sierras Bayas rocks. They show: (1) an age of 769 +- 12 Ma with ( 87 Sr/ 86 Sr) 0 = 0.7121 +- 0.0005, for Aust Quarry rocks; and (2) an age of 723 +- 21 Ma with ( 87 Sr/ 86 Sr) 0 = 0.7171 +- 0.0012 for Cerro Negro and Losa Quarries rocks. Considering the above-mentioned isochron data and the mineralogy of the clays studied, the conclusion is drawn that the ages obtained reflect the isotopic setting of a late diagenetic process, dated back to nearly 720 Ma. K-Ar data also support the Rb-Sr isochrons and the late diagenetic clay origin. The lower section of La Tinta sequence in the Sierras Bayas area must then be considered as Upper Proterozoic in age. These new data support the recently reported stratigraphical divisions and ages. (Auth.)

Sedimentary architecture of a Plio-Pleistocene proto-back-arc basin: Wanganui Basin, New Zealand

Science.gov (United States)

Proust, Jean-Noël; Lamarche, Geoffroy; Nodder, Scott; Kamp, Peter J. J.

2005-11-01

The sedimentary architecture of active margin basins, including back-arc basins, is known only from a few end-members that barely illustrate the natural diversity of such basins. Documenting more of these basins types is the key to refining our understanding of the tectonic evolution of continental margins. This paper documents the sedimentary architecture of an incipient back-arc basin 200 km behind the active Hikurangi subduction margin, North Island, New Zealand. The Wanganui Basin (WB) is a rapidly subsiding, Plio-Pleistocene sedimentary basin located at the southern termination of the extensional back-arc basin of the active Central Volcanic Region (TVZ). The WB is asymmetric with a steep, thrust-faulted, outer (arc-ward) margin and a gentle inner (craton-ward) margin. It contains a 4-km-thick succession of Plio-Pleistocene sediments, mostly lying offshore, composed of shelf platform sediments. It lacks the late molasse-like deposits derived from erosion of a subaerial volcanic arc and basement observed in classical back-arc basins. Detailed seismic stratigraphic interpretations from an extensive offshore seismic reflection data grid show that the sediment fill comprises two basin-scale mega-sequences: (1) a Pliocene (3.8 to 1.35 Ma), sub-parallel, regressive "pre-growth" sequence that overtops the uplifted craton-ward margin above the reverse Taranaki Fault, and (2) a Pleistocene (1.35 Ma to present), divergent, transgressive, "syn-growth" sequence that onlaps: (i) the craton-ward high to the west, and (ii) uplifted basement blocks associated with the high-angle reverse faults of the arc-ward margin to the east. Along strike, the sediments offlap first progressively southward (mega-sequence 1) and then southeastward (mega-sequence 2), with sediment transport funnelled between the craton- and arc-ward highs, towards the Hikurangi Trough through the Cook Strait. The change in offlap direction corresponds to the onset of arc-ward thrust faulting and the rise of

Shallow-seated explosions in the construction of the Motukorea tuff ring (Auckland, New Zealand): Evidence from lithic and sedimentary characteristics

Science.gov (United States)

Agustín-Flores, Javier; Németh, Károly; Cronin, Shane J.; Lindsay, Jan M.; Kereszturi, Gábor

2015-10-01

At least 52 eruption centres are scattered within the 360 km2 Auckland Volcanic Field (AVF). Motukorea, now an island in the Waitemata Harbour, is one of 39 AVF volcanoes that experienced a phreatomagmatic explosive phase, before a magmatic phase. The volcano erupted through a 200-300 m-thick, consolidated, mudstone/sandstone sequence of the Miocene Waitemata Group, which overlies the Waipapa Terrane greywacke basement. Detailed field descriptions of the sedimentary characteristics of the early phreatomagmatic deposits were carried out, along with examination of lithics. The ejecta ring deposit comprises 55 to 60 vol.% lithics, of which Waitemata Group fragments constitute approximately 90 vol.%, whereas < 10 vol.% are Waipapa fragments, suggesting a dominance of shallow fragmentation. The sedimentary characteristics of the stratigraphic sequence at Motukorea suggest a dominance of wet surges at the beginning of the eruption with progression into drier sequences upwards. This is reflected in increasing inter-bedded juvenile-pyroclast-dominated fall deposits up-sequence. These characteristics are attributed to the changing hydrogeological conditions within the diatreme and the host rocks. These findings shed light on the eruption dynamics of phreatomagmatic eruptions through consolidated rocks in the AVF and enable the depiction of a scenario of future eruptions within the field in similar substrates.

Stratigraphy of neoproterozoic sedimentary and volcano sedimentary successions of Uruguay

International Nuclear Information System (INIS)

Pecoits, E.; Aubet, N.; Oyhantcabal, P.; Sanchez Bettucci, L.

2004-01-01

Based on the new data the different characteristics of the Neoproterozoic (volcano) sedimentary succesions of Uruguay are described and discussed. Their stratigraphic tectonics and palaeoclimatic implications are analyzed.The results of the present investigations also allow to define the Maldonado Group which would beintegrated by the Playa Hermosa and Las Ventanas formations.

Late Pleistocene dune-sourced alluvial fans in coastal settings: Sedimentary facies and related processes (Mallorca, Western Mediterranean)

Science.gov (United States)

Pomar, F.; del Valle, L.; Fornós, J. J.; Gómez-Pujol, L.

2018-05-01

Aeolian-alluvial sedimentary interaction results in the formation of deposits characterized by typical alluvial sedimentary structures, but is composed of conspicuous amounts of aeolian sediments. The literature on this topic is limited and most works relate more with continental aeolian dunes or fluvial dune interference with fan bodies. Furthermore, there is a lack of examples of aeolian-alluvial sedimentary interference in coastal settings. In the western Mediterranean, there are many Pleistocene alluvial fan deposits built up partly by sediment originating from coastal dunes dismantled by alluvial streams. Very often, these deposits show a continuous sedimentary sequence through which we can derive the contribution and predominance of coastal, alluvial-colluvial and aeolian processes and their controls on landscape formation. This is an outstanding feature within coastal systems since it shows marine sediments reworked and integrated within coastal dune fields by aeolian transport, and the latter built up into alluvial fan bodies. In this sense, aeolian-alluvial interaction is the geomorphic-sedimentary expression of the coexistence and overlapping of alluvial and aeolian environments resulting in deposits sharing sedimentary features from both environments. The aim of this paper is to unravel the contribution of coastal dunes in the construction of alluvial fans bodies and identify the main sedimentary facies that constitute these deposits, as well as their climatic controls. For this reason, Es Caló fan (northern Mallorca) has been selected due to its well-exposed deposits exhibiting the alternation of aeolian, alluvial and colluvial deposits. Sedimentological and stratigraphic analyses based on 33 logs and complementary analyses demonstrate that most of the facies constituting the fan body are made up completely of marine bioclastic sands. These deposits record an alluvial fan sedimentary environment characterized by sediments inputs that do not proceed

Sedimentary Geology Context and Challenges for Cyberinfrastructure Data Management

Science.gov (United States)

Chan, M. A.; Budd, D. A.

2014-12-01

A cyberinfrastructure data management system for sedimentary geology is crucial to multiple facets of interdisciplinary Earth science research, as sedimentary systems form the deep-time framework for many geoscience communities. The breadth and depth of the sedimentary field spans research on the processes that form, shape and affect the Earth's sedimentary crust and distribute resources such as hydrocarbons, coal, and water. The sedimentary record is used by Earth scientists to explore questions such as the continental crust evolution, dynamics of Earth's past climates and oceans, evolution of the biosphere, and the human interface with Earth surface processes. Major challenges to a data management system for sedimentary geology are the volume and diversity of field, analytical, and experimental data, along with many types of physical objects. Objects include rock samples, biological specimens, cores, and photographs. Field data runs the gamut from discrete location and spatial orientation to vertical records of bed thickness, textures, color, sedimentary structures, and grain types. Ex situ information can include geochemistry, mineralogy, petrophysics, chronologic, and paleobiologic data. All data types cover multiple order-of-magnitude scales, often requiring correlation of the multiple scales with varying degrees of resolution. The stratigraphic framework needs dimensional context with locality, time, space, and depth relationships. A significant challenge is that physical objects represent discrete values at specific points, but measured stratigraphic sections are continuous. In many cases, field data is not easily quantified, and determining uncertainty can be difficult. Despite many possible hurdles, the sedimentary community is anxious to embrace geoinformatic resources that can provide better tools to integrate the many data types, create better search capabilities, and equip our communities to conduct high-impact science at unprecedented levels.

Geochemistry of sedimentary carbonates

National Research Council Canada - National Science Library

Morse, John W; Mackenzie, Fred T

1990-01-01

.... The last major section is two chapters on the global cycle of carbon and human intervention, and the role of sedimentary carbonates as indicators of stability and changes in Earth's surface environment...

Geologic processes and sedimentary system on Mars

Energy Technology Data Exchange (ETDEWEB)

Lewis, A S

1988-01-01

The subject is covered under following headings: (1) morphology and processes at the martian surface (impact craters, water and ice, landslide, aeolian processes, volcanism, chemical weathering); (2) the sedimentary system (martian geologic documentation, sedimentary balance, regolith, pyroclastics, erosion phenomena, deposit and loss of sediments) as well as (3) summary and final remarks. 72 refs.

Gestures and metaphors as indicators of conceptual understanding of sedimentary systems

Science.gov (United States)

Riggs, E. M.; Herrera, J. S.

2012-12-01

Understanding the geometry and evolution of sedimentary systems and sequence stratigraphy is crucial to the development of geoscientists and engineers working in the petroleum industry. There is a wide variety of audiences within industry who require relatively advanced instruction in this area of geoscience, and there is an equally wide array of approaches to teaching this material in the classroom and field. This research was undertaken to develop a clearer picture of how conceptual understanding in this area of sedimentary geology grows as a result of instruction and how instructors can monitor the completeness and accuracy of student thinking and mental models. We sought ways to assess understanding that did not rely on model-specific jargon but rather was based in physical expression of basic processes and attributes of sedimentary systems. Advances in cognitive science and educational research indicate that a significant part of spatial cognition is facilitated by gesture, (e.g. giving directions, describing objects or landscape features). We aligned the analysis of gestures with conceptual metaphor theory to probe the use of mental image-schemas as a source of concept representation for students' learning of sedimentary processes. In order to explore image schemas that lie in student explanations, we focused our analysis on four core ideas about sedimentary systems that involve sea level change and sediment deposition, namely relative sea level, base level, and sea-level fluctuations and resulting basin geometry and sediment deposition changes. The study included 25 students from three U.S. Midwestern universities. Undergraduate and graduate-level participants were enrolled in senior-level undergraduate courses in sedimentology and stratigraphy. We used semi-structured interviews and videotaping for data collection. We coded the data to focus on deictic, iconic, and metaphoric gestures, and coded interview transcripts for linguistic metaphors using the

Western Canada Sedimentary Basin competitiveness

International Nuclear Information System (INIS)

Millar, R.H.G.

1996-01-01

Recent dramatic expansion of the natural gas industry in the Western Canada Sedimentary Basin provided ample proof of the potential of this area for further development of natural gas supply. However, the inherent competitive advantages provided by the Western Canada Sedimentary Basin were said to have been offset by low netback prices resulting in poor producer economics when competitiveness is measured by availability of opportunities to find and develop gas supply at costs low enough to ensure attractive returns. Technology was identified as one of the key elements in improving basin competitiveness, but the greatest potential lies in reduced transportation costs and increased access to North American market centres. 8 figs

Micro-analysis by U-Pb method using LAM-ICPMS and its applications for the evolution of sedimentary basins: the example from Brasilia Belt

International Nuclear Information System (INIS)

Pimentel, Marcio Martins; Matteini, Massimo; Junges, Sergio Luiz; Giustina, Maria Emilia Schutesky Della; Dantas, Elton Luiz; Buhn, Bernhard

2015-01-01

The U-Pb geochronological method using LAM-MC-ICPMS represents an important tool to investigate the geological evolution of sedimentary basins, as well as its geochronology, through the determination of upper limits for the depositional ages of detrital sedimentary rocks. The method has been applied in the Geochronology Laboratory of the Universidade de Brasilia, and in this study, a brief review of the provenance data for the sediments of the Neoproterozoic Brasilia Belt is presented and their significance for the evolution of the orogen is discussed. The results indicate that the Paranoa and Canastra Groups represent passive margin sequences formed along the western margin of the Sao Francisco-Congo continent. The Vazante Group presents similar provenance patterns, although Sm-Nd isotopic results suggest that its upper portions had contributions from younger (Neoproterozoic) sources, possibly from the Neoproterozoic Goias Magmatic Arc. On the other hand, metasediments of the Araxa and Ibia groups contain an important proportion of material derived from Neoproterozoic sources, demonstrating that they represent syn-orogenic basins. The provenance pattern of the Bambui Group is marked by an important Neoproterozoic component, showing that it constitutes a sedimentary sequence which is younger than 600 Ma, representing a foreland basin to the Brasilia Belt. (author)

Sequence Stratigraphic Appraisal: Coastal Swamp Depobelt In The ...

African Journals Online (AJOL)

Mid-Lower Miocene Agbada sedimentary intercalations of “AB” Field in the coastal swamp depobelt, Western Niger-Delta, were evaluated to determine their sequence stratigraphic character. The analysis was based on a combination of data sets including logs of six wells to describe lithic variations of the Agbada Formation ...

Study on evaluation method for heterogeneous sedimentary rocks based on forward model

International Nuclear Information System (INIS)

Masui, Yasuhiro; Kawada, Koji; Katoh, Arata; Tsuji, Takashi; Suwabe, Mizue

2004-02-01

It is very important to estimate the facies distribution of heterogeneous sedimentary rocks for geological disposal of high level radioactive waste. The heterogeneousness of sedimentary rocks is due to variable distribution of grain size and mineral composition. The objective of this study is to establish the evaluation method for heterogeneous sedimentary rocks based on forward model. This study consisted of geological study for Horonobe area and the development of soft wear for sedimentary model. Geological study was composed of following items. 1. The sedimentary system for Koetoi and Wakkanai formations in Horonobe area was compiled based on papers. 2. The cores of HDB-1 were observed mainly from sedimentological view. 3. The facies and compaction property of argillaceous rocks were studied based on physical logs and core analysis data of wells. 4. The structure maps, isochrone maps, isopach maps and restored geological sections were made. The soft wear for sedimentary model to show sedimentary system on a basin scale was developed. This soft wear estimates the facies distribution and hydraulic conductivity of sedimentary rocks on three dimensions scale by numerical simulation. (author)

Sedimentary and faunal sequence of the Wadhurst clay Wealden in boreholes at Wadhurst Park, Sussex

Energy Technology Data Exchange (ETDEWEB)

Anderson, F W; Bazley, R A.B.; Shephard-Thorn, E R

1967-01-01

Three boreholes sunk at Wadhurst Park, Sussex, provide a virtually complete section through the Wadhurst Clay (Wealden, Lower Cretaceous) in its type area. Full lithological logs of the boreholes with discussions of rock types, sedimentary features and depositional environments are given. It is suggested the sediments were deposited under shallow-water lagoonal conditions which varied from fresh-water to brackish and possibly marine. The succession of ostracod assemblages as found in the boreholes is recorded and compared with that found in the Warlingham (Surrey), Chilcombe Down No. 1 (Hampshire) and Kingsclere No. 1 (Hampshire) boreholes. Ostracods including a number of new species and subspecies, all belonging to the genus Cypridea, are described together with notes on the morphology of that genus. (22 refs.)

Tracing contaminant pathways in sandy heterogeneous glaciofluvial sediments using a sedimentary depositional model

International Nuclear Information System (INIS)

Webb, E.K.; Anderson, M.P.

1990-01-01

Heterogeneous sedimentary deposits present complications for tracking contaminant movement by causing a complex advective flow field. Connected areas of high conductivity produce so-called fast paths that control movement of solutes. Identifying potential fast paths and describing the variation in hydraulic properties was attempted through simulating the deposition of a glaciofluvial deposit (outwash). Glaciofluvial deposits usually consist of several depositional facies, each of which has different physical characteristics, depositional structures and hydraulic properties. Therefore, it is unlikely that the property of stationarity (a constant mean hydraulic conductivity and a mono-modal probability distribution) holds for an entire glaciofluvial sequence. However, the process of dividing an outwash sequence into geologic facies presumably identifies units of material with similar physical characteristics. It is proposed that patterns of geologic facies determined by field observation can be quantified by mathematical simulation of sediment deposition. Subsequently, the simulated sediment distributions can be used to define the distribution of hydrogeologic parameters and locate possible fast paths. To test this hypothesis, a hypothetical glacial outwash deposit based on geologic facies descriptions contained in the literature was simulated using a sedimentary depositional model, SEDSIM, to produce a three-dimensional description of sediment grain size distributions. Grain size distributions were then used to estimate the spatial distribution of hydraulic conductivity. Subsequently a finite-difference flow model and linked particle tracking algorithm were used to trace conservative transport pathways. This represents a first step in describing the spatial heterogeneity of hydrogeologic characteristics for glaciofluvial and other braided stream environments. (Author) (39 refs., 7 figs.)

subsurface sequence delineation and saline water mapping of lagos

African Journals Online (AJOL)

A subsurface sequence delineation and saline water mapping of Lagos State was carried out. Ten (10) deep boreholes with average depth of 300 m were drilled within the sedimentary basin. The boreholes were lithologically and geophysically logged. The driller's lithological logs aided by gamma and resistivity logs, ...

Prediction of thermal conductivity of sedimentary rocks from well logs

DEFF Research Database (Denmark)

Fuchs, Sven; Förster, Andrea

2014-01-01

The calculation of heat-flow density in boreholes requires reliable values for the change of temperature and rock thermal conductivity with depth. As rock samples for laboratory measurements of thermal conductivity (TC) are usually rare geophysical well logs are used alternatively to determine TC...... parameters (i.e. thermal conductivity, density, hydrogen index, sonic interval transit time, gamma-ray response, photoelectric factor) of artificial mineral assemblages consisting 15 rock-forming minerals that are used in different combinations to typify sedimentary rocks. The predictive capacity of the new...... equations is evaluated on subsurface data from four boreholes drilled into the Mesozoic sequence of the North German Basin, including more than 1700 laboratory-measured thermal-conductivity values. Results are compared with those from other approaches published in the past. The new approach predicts TC...

Lithofacies-paleo-geography and uranium sedimentary facies in Hailar basin

International Nuclear Information System (INIS)

Qi Fucheng

1992-01-01

Cretaceous-Tertiary sedimentary paleo-structure and lithofacies-paleo-geography in Hailar Basin are described. Taking Chenqi coal field as an example, the sedimentary facies pattern of coal-bearing series characterized by alternating sedimentation of fluviatile and lacustrine-swampy facies is reconstructed. It is pointed out that this sedimentary facies not only controls the sedimentation and distribution of syngenetic uranium mineralization, but also is a favourable place that converges uranium-bearing solution and reduces and precipitates uranium for the second time in epigenetic mineralization

Sedimentary constraints on the duration of the Marinoan Oxygen-17 Depletion (MOSD) event

Science.gov (United States)

Killingsworth, Bryan A.; Hayles, Justin A.; Zhou, Chuanming; Bao, Huiming

2013-10-01

The ∼635 Ma Marinoan glaciation is marked by dramatic Earth system perturbations. Deposition of nonmass-dependently 17O-depleted sulfate (SO42-) in worldwide postglacial sediments is, thus far, unique to this glaciation. It is proposed that an extremely high-pCO2 atmosphere can result in highly 17O-depleted atmospheric O2, or the Marinoan Oxygen-17 Depletion (MOSD) event. This anomalous 17O signal was imparted to sulfate of oxidative weathering origin. However, 17O-depleted sulfate occurs in limited sedimentary intervals, suggesting that Earth surface conditions conducive to the MOSD had a finite duration. An MOSD duration can, therefore, provide much needed constraint on modeling Earth system responses at that time. Unfortunately, the sulfate 17O record is often sparse or lacks radiometric dates. Here, we report 11 barite layers from a post-Marinoan dolostone sequence at Wushanhu in the South China Block. The 17O depletion fluctuates in magnitude in lower layers but is persistently absent up section, providing the most confident first and last sedimentary appearance of the anomaly. δ13C chemostratigraphy is used to correlate the Wushanhu section to two proximal sections on the same shallow platform that lack barite layers but have published U-Pb dates that occur in dolostone and shale. Assuming a similar pattern and rate for carbonate and shale deposition among the different sections, we estimate the MOSD duration at 0-0.99 My. This number can be further constrained by new radiometric dates from equivalent sequences worldwide, thus underpinning models on the nonsteady-state Earth system response in the immediate aftermath of the Marinoan meltdown.

Cyclicity recorded in the provenance sandstones in the sedimentary in fill of the Cameros basin (N. Spain)

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Acebron, L.; Arribas, J.; Omodeo-Sale, S.; Arribas, E.; Le Pera, E.; Mas, R.; Lopez-Elorza, M.; Fernandez-Diaz, P. R.

2013-06-01

The intra plate Cameros rift basin in the north of Spain was formed came into being between the Tithonian and the Early Albian and contains 9 000 m of mostly continental sediments. This basin is a good example of cyclicity of different depositional sequences (DSs) in sedimentary environments, which show clear repetition in their sandstone composition (petrofacies) and diagenetic patterns. The DSs are arranged in two mega sequences (MSs) separated by a tectonic unconformity. A similar vertical sandstone compositional evolution, subdivided into two stages that repeat cyclically, has been recognised in both MSs: the first comprises quartzo-sedimentolithic petrofacies and the second is made up of several quartzo-feldspathic petrofacies. This was caused by a progression from the recycling of the pre-rift sedimentary cover to the erosion of the mainly plutonic and metamorphic crystalline basement. These changes in the erosion of the different source areas were conditioned by the tectonics of the basin. Furthermore, the original sandstone framework composition conditioned the diagenetic pattern of the two stages: quartzo-sedimentolithic sandstones containing large amounts of very pervasive carbonate cement that reduce their original porosity considerably, and quartzo-feldspathic petrofacies with a rigid framework that maintained the original pores during burial diagenesis. This compositional and diagenetic pattern is probably applicable to other non-volcanic rifted basins, depending upon the original amount of carbonate rock fragments present. (Author)

Study of the argillaceous fraction of sedimentary sequences of Meuse and Gard. Reconstitution of the diagenetic history and of the physico-chemical characteristics of the targets. Mineralogical, geochemical and isotopic aspects; Etude de la fraction argileuse de sequences sedimentaires de la Meuse et du Gard. Reconstitution de l'histoire diagenetique et des caracteristiques physico-chimiques des cibles. Aspects mineralogiques, geochimiques et isotopiques

Energy Technology Data Exchange (ETDEWEB)

Rousset, D

2002-01-01

Very low permeable argillaceous rocks like Callovo-Oxfordian clay-stones or Vraconian siltstones were chosen to host a research laboratory built to determine the physico-chemical properties of the host formations for a potential underground disposal of radioactive waste. Knowledge and understanding of post-sedimentary modifications are of prime importance for definition of these properties; evaluation and quantification of the post-sedimentary changes represent the aim of this study, focused specifically on the clay material of the sequences. Samples were taken from two drillings (HTM102 and MAR501). In the HTM102 core samples, illite and mixed-layers illite/smectite are the dominant clay components of most clay fractions. Systematic SEM and TEM observations and isotopic K-Ar and Rb-Sr analyses pointed to diagenetic neo-formations of carbonates (calcite, dolomite) and clays. For instance, veils and laths of authigenic clay particles around old detrital ones can distinctly be observed. The epoch, duration and extent of the diagenetic activity(ies) are difficult to evaluate because of an overall detrital contribution even in the finest granulometric fractions. However; analysis of a bentonite layer in the sequence provides a diagenetic reference for the authigenic clay material. Correlation between relative sea level and authigenesis of smectite-rich mineral has been outlined. Chemistry of diagenetic fluids also seems to be reliable with sea level variations. These observations argue in favour of diagenetic activities limited in restricted rock volumes. The case study of MAR501 is close to the HTM102 one: smectite-rich illite/smectite mixed-layers represent the major component of the clay fraction and K-Ar values argue ire the sense of a mixing between detrital and younger clay populations. Diagenetic glauconites in the sequence yield are age close to 93,7 {+-}0,3 Ma for Vraconian level, in agreement with stratigraphical data. The case study of a clay-filled fault

Study of the argillaceous fraction of sedimentary sequences of Meuse and Gard. Reconstitution of the diagenetic history and of the physico-chemical characteristics of the targets. Mineralogical, geochemical and isotopic aspects; Etude de la fraction argileuse de sequences sedimentaires de la Meuse et du Gard. Reconstitution de l'histoire diagenetique et des caracteristiques physico-chimiques des cibles. Aspects mineralogiques, geochimiques et isotopiques

Energy Technology Data Exchange (ETDEWEB)

Rousset, D

2002-01-01

Very low permeable argillaceous rocks like Callovo-Oxfordian clay-stones or Vraconian siltstones were chosen to host a research laboratory built to determine the physico-chemical properties of the host formations for a potential underground disposal of radioactive waste. Knowledge and understanding of post-sedimentary modifications are of prime importance for definition of these properties; evaluation and quantification of the post-sedimentary changes represent the aim of this study, focused specifically on the clay material of the sequences. Samples were taken from two drillings (HTM102 and MAR501). In the HTM102 core samples, illite and mixed-layers illite/smectite are the dominant clay components of most clay fractions. Systematic SEM and TEM observations and isotopic K-Ar and Rb-Sr analyses pointed to diagenetic neo-formations of carbonates (calcite, dolomite) and clays. For instance, veils and laths of authigenic clay particles around old detrital ones can distinctly be observed. The epoch, duration and extent of the diagenetic activity(ies) are difficult to evaluate because of an overall detrital contribution even in the finest granulometric fractions. However; analysis of a bentonite layer in the sequence provides a diagenetic reference for the authigenic clay material. Correlation between relative sea level and authigenesis of smectite-rich mineral has been outlined. Chemistry of diagenetic fluids also seems to be reliable with sea level variations. These observations argue in favour of diagenetic activities limited in restricted rock volumes. The case study of MAR501 is close to the HTM102 one: smectite-rich illite/smectite mixed-layers represent the major component of the clay fraction and K-Ar values argue ire the sense of a mixing between detrital and younger clay populations. Diagenetic glauconites in the sequence yield are age close to 93,7 {+-}0,3 Ma for Vraconian level, in agreement with stratigraphical data. The case study of a clay-filled fault

Archaen to Recent aeolian sand systems and their sedimentary record

DEFF Research Database (Denmark)

Rodríguez-López, Juan Pedro; Clemmensen, Lars B; Lancaster, Nick

2014-01-01

The sedimentary record of aeolian sand systems extends from the Archean to the Quaternary, yet current understanding of aeolian sedimentary processes and product remains limited. Most preserved aeolian successions represent inland sand-sea or dunefield (erg) deposits, whereas coastal systems are ...

The Neogene molasse deposits of the Zagros Mountains in central Dezful Embayment: facies, sedimentary environments and controls

Directory of Open Access Journals (Sweden)

Ali Hossein Jalilian

2016-03-01

Full Text Available The upper part of Neogene sequence of the Zagros Mountains consists of a clastic succession which is identified as Aghajari and Bakhtyari formations. The sequence is an excellent example of synorogenic sedimentation or molasse deposited in northern portion of the Zagros foreland basin. Sedimentological analysis of an outcrop section representing Miocene-Pliocene sediments in central Dezful Embayment resulted in recognizing 9 lithofacies and 4 architectural elements. These lithofacies include conglometate (Gt, Gh, Gmm, sandstone (Sp, Sh, Sr, St and mudstone (Fm, Fl that were deposited in meandering stream, braided river and alluvial fan environments. Paleocurrent analysis of cross-beds, channels and asymmetric ripple marks indicate that these Neogene clastics were mainly drived from Cretaceous to Paleogene highlands in the Zagros Mountains on the north. This stratigraphic record is coarsening-upward and formed by a regressive depositional megacycle under arid climate. Facies and depositional history analysis show that sedimentation of the Zagros molasse was primarily controlled by base-level changes rather than catchment lithology or climate. The sedimentary record of this regressive megacycle reveales the base-level was constantly falling down on one hand and the provenance was uplifting on the other hand. Tectonic activities and Zagros Mountains rising in the Late Miocene resulted in deposition of fining-upward point-bar and floodplain sequences of the Aghajari Formation in low-gradient meandering streams. The Lahbari Member of the Aghajari Formation represents deposition in braided rivers that composed predominantly of flood-plain deposits in the Early Pliocene. Finally, the sedimentary cycle of the Zagros molasse deposits terminated with massive conglomerates of the Bakhtyari Formation deposited in large alluvial fans near the source area.

Direct stable isotope porewater equilibration and identification of groundwater processes in heterogeneous sedimentary rock

Energy Technology Data Exchange (ETDEWEB)

David, Katarina, E-mail: k.david@student.unsw.edu.au [School of Mining Engineering, UNSW Australia, NSW 2052 (Australia); Connected Waters Initiative Research Centre, UNSW Australia, NSW 2052 (Australia); Timms, Wendy [School of Mining Engineering, UNSW Australia, NSW 2052 (Australia); Connected Waters Initiative Research Centre, UNSW Australia, NSW 2052 (Australia); Baker, Andy [Connected Waters Initiative Research Centre, UNSW Australia, NSW 2052 (Australia)

2015-12-15

The off-axis integrated cavity output spectrometry (ICOS) method to analyse porewater isotopic composition has been successfully applied over the last decade in groundwater studies. This paper applies the off-axis ICOS method to analyse the porewater isotopic composition, attempts to use the isotopic shift in groundwater values along with simple geochemical mixing model to define the groundwater processes in the Sydney Basin, Australia. Complementary data included geophysical, hydrogeological, geochemical, and mineralogical investigations. Porewater from core samples were analysed for δ{sup 18}O and δ{sup 2}H from various sedimentary units in the Basin and compared to endpoint water members. Stable δ{sup 18}O and δ{sup 2}H values of porewaters in the Basin (− 9.5 to 2.8‰ for δ{sup 18}O and − 41.9 to 7.9‰ for δ{sup 2}H) covered a relatively narrow range in values. The variability in water isotopes reflects the variability of the input signal, which is the synoptic variability in isotopic composition of rainfall, and to a minor extent the subsequent evaporation. The porosity, bulk density and mineralogy data demonstrate the heterogeneity that adds the complexity to variations in the isotope profile with depth. The source of chloride in the sedimentary sequence was related to rock–water and cement/matrix–water interaction rather than to evaporation. The heterogeneous character of the sedimentary rock strata was supported by a change in pore pressures between units, density and variability in rock geochemical analyses obtained by using X-ray fluorescence (XRF) and X-ray power diffraction analyses. This research identified distinct hydrogeological zones in the Basin that were not previously defined by classic hydrogeological investigations. Isotopic signature of porewaters along the detailed vertical profile in combination with mineralogical, geochemical, geophysical and hydrogeological methods can provide useful information on groundwater movement in

When did the Penglai orogeny begin on Taiwan?: Geochronological and petrographic constraints on the exhumed mountain belts and foreland-basin sequences

Science.gov (United States)

Chen, W. S.; Syu, S. J.; Yeh, J. J.

2017-12-01

Foreland basin receives large amounts of synorogenic infill that is eroded from the adjacent exhumed mountain belt, and therefore provides the important information on exhumation evolution. Furthermore, a complete stratigraphic sequence of Taiwan mountain belt consists of five units of Miocene sedimentary rocks (the Western Foothills and the uppermost sequence on the proto-Taiwan mountain belt), Oligocene argillite (the Hsuehshan Range), Eocene quartzite (the Hsuehshan Range), Eocene-Miocene slate and schist (Backbone Range), and Cretaceous schist (Backbone Range) from top to bottom. Based on the progressive unroofing history, the initiation of foreland basin received sedimentary lithic sediments from the uppermost sequence of proto-Taiwan mountain belt, afterwards, and receiving low- to medium-grade metamorphic lithic sediments in ascending order of argillite, quartzite, slate, and schist clasts. Therefore, the sedimentary lithics from mountain belt were deposited which represents the onset of the mountain uplift. In this study, the first appearance of sedimentary lithic sediments occurs in the Hengchun Peninsula at the middle Miocene (ca. 12-10 Ma). Thus, sandstone petrography of the late Miocene formation (10-5.3 Ma) shows a predominantly recycled sedimentary and low-grade metamorphic sources, including sandstone, argillite and quartzite lithic sediments of 10-25% which records erosion to slightly deeper metamorphic terrane on the mountain belt. Based on the results of previous thermogeochronological studies of the Yuli belt, it suggests that the middle Miocene occurred mountain uplift. The occurrence of low-grade metamorphic lithic sediments in the Hengchun Peninsula during late Miocene is coincident with the cooling ages of uplift and denuded Yuli schist belt at the eastern limb of Backbone Range.

PREDICTED SEDIMENTARY SECTION OF SUBGLACIAL LAKE VOSTOK

Directory of Open Access Journals (Sweden)

G. I. Leychenkov

2012-01-01

Full Text Available In early February 2012, the drill hole at the Vostok Station encountered theLakeVostokwater. This step is important to study the lake composition including possible microbial life and to model subglacial environments however, the next ambitious target of the Vostok Drilling Project is sampling of bottom sediments, which contain the unique record of ice sheet evolution and environmental changes in centralAntarcticafor millions of years. In this connection, the forecast of sedimentary succession based on existing geophysical data, study of mineral inclusions in the accretion ice cores and tectonic models is important task. Interpretation of Airborne geophysical data suggests thatLakeVostokis the part of spacious rift system, which exists at least from Cretaceous. Reflection and refraction seismic experiments conducted in the southern part ofLakeVostokshow very thin (200–300 m stratified sedimentary cover overlying crystalline basement with velocity of 6.0–6.2 km/s. At present, deposition in southernLakeVostokis absent and similar conditions occurred likely at least last3 m.y. when ice sheet aboveLakeVostokchanged insignificantly. It can be also inferred that from the Late Miocene the rate of deposition inLakeVostokwas extremely low and so the most of sedimentary section is older being possibly of Oligocene to early to middle Miocene age when ice sheet oscillated and deposition was more vigorous. If so, the sampling of upper few meters of this condensed section is very informative in terms of history of Antarctic glaciation. Small thickness of sedimentary cover raises a question about existence of lake (rift depression during preglacial and early glacial times.

Study on investigation and evaluation methods of deep seated sedimentary rocks. Chemical weathering, pore water squeezing and relationships of physical properties of sedimentary rocks

International Nuclear Information System (INIS)

Oyama, Takahiro; Suzuki, Koichi

2006-01-01

Chemical weathering, porewater squeezing and physical properties for the sedimentary rocks were examined. Chemical weathering potential of rocks was described by the sulfur as a acceleration factor of weathering and carbonate contents as a neutralization factor of it. The carbonate contents in the rocks were measured accurately by the gas pressure measurement method. Pore water squeezing method was applied for the semi-hard sedimentary rocks (Opalinusclay). The chemical change of extracted pore water under high pressure conditions was estimated. Physical property of sedimentary rocks have relationship among the porosity and permeability and resistivity coefficient in the same rock types. It is possible to estimate the water permeability from the geophysical tests. (author)

Building a Bridge to Deep Time: Sedimentary Systems Across Timescales

Science.gov (United States)

Romans, B.; Castelltort, S.; Covault, J. A.; Walsh, J. P.

2013-12-01

It is increasingly important to understand the complex and interdependent processes associated with sediment production, transport, and deposition at timescales relevant to civilization (annual to millennial). However, predicting the response of sedimentary systems to global environmental change across a range of timescales remains a significant challenge. For example, a significant increase in global average temperature at the Paleocene-Eocene boundary (55.8 Ma) is interpreted to have occurred over millennial timescales; however, the specific response of sedimentary systems (e.g., timing and magnitude of sediment flux variability in river systems) to that forcing is debated. Thus, using such environmental perturbations recorded in sedimentary archives as analogs for ongoing/future global change requires improved approaches to bridging across time. Additionally, the ability to bridge timescales is critical for addressing other questions about sedimentary system behavior, including signal propagation and signal versus ';noise' in the record. The geologic record provides information that can be used to develop a comprehensive understanding of process-response behavior at multiple timescales. The geomorphic ';snapshot' of present-day erosional and depositional landscapes can be examined to reconstruct the history of processes that created the observable configurations. Direct measurement and monitoring of active processes are used to constrain conceptual and numerical models and develop sedimentary system theory. But real-time observations of active Earth-surface processes are limited to the very recent, and how such processes integrate over longer timescales to transform into strata remains unknown. At longer timescales (>106 yr), the stratigraphic record is the only vestige of ancient sedimentary systems. Stratigraphic successions contain a complex record of sediment deposition and preservation, as well as the detrital material that originated in long since denuded

Land subsidence and hydrodynamic compaction of sedimentary basins

Directory of Open Access Journals (Sweden)

H. Kooi

1998-01-01

Full Text Available A one-dimensional model is used to investigate the relationship between land subsidence and compaction of basin sediments in response to sediment loading. Analysis of the model equations and numerical experiments demonstrate quasi-linear systems behaviour and show that rates of land subsidence due to compaction: (i can attain a significant fraction (>40% of the long-term sedimentation rate; (ii are hydrodynamically delayed with respect to sediment loading. The delay is controlled by a compaction response time τc that can reach values of 10-5-107 yr for thick shale sequences. Both the behaviour of single sediment layers and multiple-layer systems are analysed. Subsequently the model is applied to the coastal area of the Netherlands to illustrate that lateral variability in compaction-derived land subsidence in sedimentary basins largely reflects the spatial variability in both sediment loading and compaction response time. Typical rates of compaction-derived subsidence predicted by the model are of the order of 0.1 mm/yr but may reach values in excess of 1 mm/yr under favourable conditions.

Elemental Geochemistry of Sedimentary Rocks at Yellowknife Bay, Gale Crater, Mars

Science.gov (United States)

McLennan, S. M.; Anderson, R. B.; Bell, J. F.; Bridges, J. C.; Calef, F.; Campbell, J. L.; Clark, B. C.; Clegg, S.; Conrad, P.; Cousin, A.; Des Marais, D. J.; Dromart, G.; Dyar, M. D.; Edgar, L. A.; Ehlmann, B. L.; Fabre, C.; Forni, O.; Gasnault, O.; Gellert, R.; Gordon, S.; Grant, J. A.; Grotzinger, J. P.; Gupta, S.; Herkenhoff, K. E.; Hurowitz, J. A.; King, P. L.; Le Mouélic, S.; Leshin, L. A.; Léveillé, R.; Lewis, K. W.; Mangold, N.; Maurice, S.; Ming, D. W.; Morris, R. V.; Nachon, M.; Newsom, H. E.; Ollila, A. M.; Perrett, G. M.; Rice, M. S.; Schmidt, M. E.; Schwenzer, S. P.; Stack, K.; Stolper, E. M.; Sumner, D. Y.; Treiman, A. H.; VanBommel, S.; Vaniman, D. T.; Vasavada, A.; Wiens, R. C.; Yingst, R. A.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Farmer, Jack; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; Blank, Jennifer; Weigle, Gerald; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Farley, Kenneth; Griffes, Jennifer; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Siebach, Kirsten; Brunet, Claude; Hipkin, Victoria; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Kemppinen, Osku; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Bish, David; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; d'Uston, Claude; Lasue, Jérémie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Israël, Guy; Szopa, Cyril; Robert, François; Sautter, Violaine; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Edgett, Kenneth; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; Malin, Michael; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Goetz, Walter; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Fassett, Caleb; Blake, David F.; Bristow, Thomas; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Wilhelm, Mary Beth; Bleacher, Lora; Brinckerhoff, William; Choi, David; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Jones, Andrea; Mahaffy, Paul; Martin, David K.; McAdam, Amy; Pavlov, Alexander; Raaen, Eric; Smith, Michael D.; Stern, Jennifer; Tan, Florence; Trainer, Melissa; Meyer, Michael; Posner, Arik; Voytek, Mary; Anderson, Robert C.; Aubrey, Andrew; Beegle, Luther W.; Behar, Alberto; Blaney, Diana; Brinza, David; Christensen, Lance; Crisp, Joy A.; DeFlores, Lauren; Ehlmann, Bethany; Feldman, Jason; Feldman, Sabrina; Flesch, Gregory; Jun, Insoo; Keymeulen, Didier; Maki, Justin; Mischna, Michael; Morookian, John Michael; Parker, Timothy; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; Juarez, Manuel de la Torre; Webster, Christopher R.; Yen, Albert; Archer, Paul Douglas; Cucinotta, Francis; Jones, John H.; Niles, Paul; Rampe, Elizabeth; Nolan, Thomas; Fisk, Martin; Radziemski, Leon; Barraclough, Bruce; Bender, Steve; Berman, Daniel; Dobrea, Eldar Noe; Tokar, Robert; Williams, Rebecca M. E.; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Vicenzi, Edward; Wilson, Sharon A.; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Wolff, Michael; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Ávalos, Juan José Blanco; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; Navarro-González, Rafael; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Dietrich, William; Kortmann, Onno; Palucis, Marisa; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Rubin, David; Jakosky, Bruce; Balic-Zunic, Tonci; Frydenvang, Jens; Jensen, Jaqueline Kløvgaard; Kinch, Kjartan; Koefoed, Asmus; Madsen, Morten Bo; Stipp, Susan Louise Svane; Boyd, Nick; Pradler, Irina; Jacob, Samantha; Owen, Tobias; Rowland, Scott; Atlaskin, Evgeny; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mueller-Mellin, Reinhold; Wimmer-Schweingruber, Robert; McConnochie, Timothy; Benna, Mehdi; Franz, Heather; Bower, Hannah; Brunner, Anna; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Atreya, Sushil; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Kah, Linda C.; Moersch, Jeffrey; Tate, Christopher; Day, Mackenzie; Kocurek, Gary; Hallet, Bernard; Sletten, Ronald; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Kuzmin, Ruslan; Arvidson, Raymond; Fraeman, Abigail; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey; Moores, John E.

2014-01-01

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

Elemental geochemistry of sedimentary rocks at Yellowknife Bay, Gale crater, Mars.

Science.gov (United States)

McLennan, S M; Anderson, R B; Bell, J F; Bridges, J C; Calef, F; Campbell, J L; Clark, B C; Clegg, S; Conrad, P; Cousin, A; Des Marais, D J; Dromart, G; Dyar, M D; Edgar, L A; Ehlmann, B L; Fabre, C; Forni, O; Gasnault, O; Gellert, R; Gordon, S; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; King, P L; Le Mouélic, S; Leshin, L A; Léveillé, R; Lewis, K W; Mangold, N; Maurice, S; Ming, D W; Morris, R V; Nachon, M; Newsom, H E; Ollila, A M; Perrett, G M; Rice, M S; Schmidt, M E; Schwenzer, S P; Stack, K; Stolper, E M; Sumner, D Y; Treiman, A H; VanBommel, S; Vaniman, D T; Vasavada, A; Wiens, R C; Yingst, R A

2014-01-24

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

Discontinuities and sequences in the Tarat formation (Upper Visean) and the Arlit Unit (Namurian-Westphalian) at Arlit (Niger). Sedimentary climatic and tectonic evolution of the area during Carboniferous

International Nuclear Information System (INIS)

Sempere, T.; Beaudoin, B.

1984-01-01

The Tarat Formation is composed at Arlit of three sequences consisting of sandstones and black mudstones rich in organic matter of continental origin. The three of them are interpreted as estuarine sediments deposited in different tectonic frameworks. The Arlit Unit consists of motley argillaceous sandstones deposited in a very flat lacustrine or alluvial environment and under an arid climate. These formations are separated by a fundamental discontinuity linked to the structuration of the Tim Mersoi Trough. At regional scale, the sediments lying below this discontinuity are grouped in tectono-sedimentary supersequences, which are interpreted as biorhexistasic rhythms; their deposition was horizontally directed by complex evolving synsedimentary tectonics controlled by the N-S In Azawa Lineament, and was influenced by the permanent proximity of a northern sea. The sediments lying above the fundamental discontinuity belong to the ''Continental Intercalaire'' Supergroup; their deposition was influenced by the Tim Mersoi Trough. The whole Carboniferous sedimentation took place in a climatic context which evolved from cold (Lower Visean) to warm and arid (Upper Carboniferous) through temperate climates [fr

Sequence stratigraphy and uranium metallogenic characteristics in Xinminpu group, lower cretaceous, in Gongpoquan basin

International Nuclear Information System (INIS)

Gong Binli; Wang Jingping

2006-01-01

Characteristics of sequence stratigraphy, the distribution and the geologic time of sequence, boundary features and internal composition, the sedimentary facies, as well as the characteristics of interlayer oxidation zone and U-mineralization are expounded. It is suggested that the Gongpoquan area is of certain prospect for U-prospecting, and uranium metallogenic conditions are not favorable in the Beiluotuoquan area, and the Nalinsuhuai area has no prospect either. (authors)

Sedimentary structures of tidal flats

Indian Academy of Sciences (India)

Sedimentary structures of some coastal tropical tidal flats of the east coast of India, and inner estuarine tidal point bars located at 30 to 50 kilometers inland from the coast, have been extensively studied under varying seasonal conditions. The results reveal that physical features such as flaser bedding, herringbone ...

Sedimentary environments: processes, facies, and stratigraphy

National Research Council Canada - National Science Library

Reading, H. G; Reading, Harold G

1996-01-01

... and chemical systems, 6 2.1.2 Climate, 7 2.1.3 Tectonic movements and subsidence, 11 2.1.4 Sea-level changes, 11 2.1.5 Milankovitch processes and orbital forcing, 14 2.1.6 Intrinsic sedimentary processes,...

The sedimentary dynamics in natural and human-influenced delta channel belts

NARCIS (Netherlands)

Hobo, N.

2015-01-01

This study investigates the increased anthropogenic influence on the within-channel belt sedimentary dynamics in the Rhine delta. To make this investigation, the sedimentary dynamics within the life-cycle of a single channel belt were reconstructed for three key periods of increasing human impact,

Sedimentary architecture of a sub-lacustrine debris fan: Eocene Dongying Depression, Bohai Bay Basin, east China

Science.gov (United States)

Liu, Jianping; Xian, Benzhong; Wang, Junhui; Ji, Youliang; Lu, Zhiyong; Liu, Saijun

2017-12-01

The sedimentary architectures of submarine/sublacustrine fans are controlled by sedimentary processes, geomorphology and sediment composition in sediment gravity flows. To advance understanding of sedimentary architecture of debris fans formed predominantly by debris flows in deep-water environments, a sub-lacustrine fan (Y11 fan) within a lacustrine succession has been identified and studied through the integration of core data, well logging data and 3D seismic data in the Eocene Dongying Depression, Bohai Bay Basin, east China. Six types of resedimented lithofacies can be recognized, which are further grouped into five broad lithofacies associations. Quantification of gravity flow processes on the Y11 fan is suggested by quantitative lithofacies analysis, which demonstrates that the fan is dominated by debris flows, while turbidity currents and sandy slumps are less important. The distribution, geometry and sedimentary architecture are documented using well data and 3D seismic data. A well-developed depositional lobe with a high aspect ratio is identified based on a sandstone isopach map. Canyons and/or channels are absent, which is probably due to the unsteady sediment supply from delta-front collapse. Distributary tongue-shaped debris flow deposits can be observed at different stages of fan growth, suggesting a lobe constructed by debrite tongue complexes. Within each stage of the tongue complexes, architectural elements are interpreted by wireline log motifs showing amalgamated debrite tongues, which constitute the primary fan elements. Based on lateral lithofacies distribution and vertical sequence analysis, it is proposed that lakefloor erosion, entrainment and dilution in the flow direction lead to an organized distribution of sandy debrites, muddy debrites and turbidites on individual debrite tongues. Plastic rheology of debris flows combined with fault-related topography are considered the major factors that control sediment distribution and fan

Late Miocene volcanic sequences in northern Victoria Land, Antarctica: products of glaciovolcanic eruptions under different thermal regimes

Science.gov (United States)

Smellie, J. L.; Rocchi, S.; Armienti, P.

2011-01-01

Late Miocene (c. 13-5 Ma) volcanic sequences of the Hallett Volcanic Province (HVP) crop out along >250 km of western Ross Sea coast in northern Victoria Land. Eight primary volcanic and six sedimentary lithofacies have been identified, and they are organised into at least five different sequence architectures as a consequence of different combinations of eruptive and/or depositional conditions. The volcanoes were erupted in association with a Miocene glacial cover and the sequences are overwhelmingly glaciovolcanic. The commonest and most representative are products of mafic aa lava-fed deltas, a type of glaciovolcanic sequence that has not been described before. It is distinguished by (1) a subaerially emplaced relatively thin caprock of aa lavas lying on and passing down-dip into (2) a thicker association of chaotic to crudely bedded hyaloclastite breccias, water-chilled lava sheets and irregular lava masses, collectively called lobe-hyaloclastite. A second distinctive sequence type present is characterised by water-cooled lavas and associated sedimentary lithofacies (diamictite (probably glacigenic) and fluvial sands and gravels) similar to some mafic glaciovolcanic sheet-like sequences (see Smellie, Earth-Science Reviews, 74, 241-268, 2008), but including (for the first time) examples of likely sheet-like sequences with felsic compositions. Other sequence types in the HVP are minor and include tuff cones, cinder cones and a single ice-marginal lacustrine sequence. The glacial thermal regime varied from polar, characterised by sequences lacking glacial erosion, glacigenic sediments or evidence for free water, to temperate or sub-polar for sequences in which all of these features are conspicuously developed.

Epigenetic alterations of sedimentary rocks at deposits

International Nuclear Information System (INIS)

Komarova, G.V.; Kondrat'eva, I.A.; Zelenova, O.I.

1980-01-01

Notions are explained, and technique for studying epigenetic alterations of sedimentary rocks at uranium deposits is described. Main types of epigenetic transformations and their mineralogic-geochemical characteristics are considered. Rock alterations, accompanying uranium mineralization, can be related to 2 types: oxidation and reduction. The main mineralogic-geochemical property of oxidation transformations is epigenetic limonitization. Stratal limonitization in primary grey-coloured terrigenic rocks and in epigenetically reduced (pyritized) rocks, as well as in rock, subjected to epigenetic gleying, are characterized. Reduction type of epigenetic transformations is subdivided into sulphidic and non-sulphidic (gley) subtypes. Sulphidic transformations in grey-coloured terrigenic rocks with organic substance of carbonic row, in rocks, containing organic substance of oil row, sulphide transformations of sedimentary rocks, as well as gley transformations, are considered

Thermal conductivity of sedimentary rocks as function of Biot’s coefficient

DEFF Research Database (Denmark)

Orlander, Tobias; Pasquinelli, Lisa; Asmussen, J.J.

2017-01-01

A theoretical model for prediction of effective thermal conductivity with application to sedimentary rocks is presented. Effective thermal conductivity of sedimentary rocks can be estimated from empirical relations or theoretically modelled. Empirical relations are limited to the empirical...... conductivity of solids is typically orders of magnitude larger than that of fluids, grain contacts constituting the solid connectivity governs the heat transfer of sedi-mentary rocks and hence should be the basis for modelling effective thermal con-ductivity. By introducing Biot’s coefficient, α, we propose (1...... – α) as a measure of the solid connectivity and show how effective thermal conductivity of water saturated and dry sandstones can be modelled....

Closure Time of the Junggar-Balkhash Ocean: Constraints From Late Paleozoic Volcano-Sedimentary Sequences in the Barleik Mountains, West Junggar, NW China

Science.gov (United States)

Liu, Bo; Han, Bao-Fu; Chen, Jia-Fu; Ren, Rong; Zheng, Bo; Wang, Zeng-Zhen; Feng, Li-Xia

2017-12-01

The Junggar-Balkhash Ocean was a major branch of the southern Paleo-Asian Ocean. The timing of its closure is important for understanding the history of the Central Asian Orogenic Belt. New sedimentological and geochronological data from the Late Paleozoic volcano-sedimentary sequences in the Barleik Mountains of West Junggar, NW China, help to constrain the closure time of the Junggar-Balkhash Ocean. Tielieketi Formation (Fm) is dominated by littoral sediments, but its upper glauconite-bearing sandstone is interpreted to deposit rapidly in a shallow-water shelf setting. By contrast, Heishantou Fm consists chiefly of volcanic rocks, conformably overlying or in fault contact with Tielieketi Fm. Molaoba Fm is composed of parallel-stratified fine sandstone and sandy conglomerate with graded bedding, typical of nonmarine, fluvial deposition. This formation unconformably overlies the Tielieketi and Heishantou formations and is conformably covered by Kalagang Fm characterized by a continental bimodal volcanic association. The youngest U-Pb ages of detrital zircons from sandstones and zircon U-Pb ages from volcanic rocks suggest that the Tielieketi, Heishantou, Molaoba, and Kalagang formations were deposited during the Famennian-Tournaisian, Tournaisian-early Bashkirian, Gzhelian, and Asselian-Sakmarian, respectively. The absence of upper Bashkirian to Kasimovian was likely caused by tectonic uplifting of the West Junggar terrane. This is compatible with the occurrence of coeval stitching plutons in the West Junggar and adjacent areas. The Junggar-Balkhash Ocean should be finally closed before the Gzhelian, slightly later or concurrent with that of other ocean domains of the southern Paleo-Asian Ocean.

Study on flow and mass transport through fractured sedimentary rocks (2)

International Nuclear Information System (INIS)

Shimo, Michito; Kumamoto, Sou; Karasaki, Kenzi; Sato, Hisashi; Sawada, Atsushi

2009-03-01

It is important for safety assessment of HLW geological disposal to understand hydro-geological conditions at the investigation area, and to evaluate groundwater flow and mass transport model and parameters, at each investigation phase. Traditionally, for Neogene sedimentary rock, the grain spacing of sediments has been considered as the dominant migration path. However, fractures of sedimentary rock could act as dominant paths, although they were soft sedimentary rocks. In this study, as part of developing groundwater flow and mass transport evaluation methodologies of such a fractured sedimentary rock' distributed area, we conducted two different scale of studies; 1) core rock sample scale and 2) several kilometer scale. For the core rock sample scale, some of laboratory hydraulic and tracer experiments have conducted using the rock cores with tailored parallel fracture, obtained at pilot borehole drilled in the vicinity of ventilation shaft. From the test results, hydraulic conductivity, diffusion coefficient, transport aperture, dispersion length and etc. was evaluated. Based on these test results, the influence of these parameters onto mass transport behavior of fractures sedimentary rocks was examined. For larger scale, such as several kilometer scale, the regional scale groundwater flow was examined using temperature data observed along the boreholes at Horonobe site. The results show that the low permeable zone between the boreholes might be estimated. (author)

The role of Mesozoic sedimentary basin tapers on the formation of Cenozoic crustal shortening structures and foredeep in the western Sichuan Basin, China

Science.gov (United States)

Wang, M.

2017-12-01

The foreland basin records important clues of tectonic and sedimentary process of mountain-building, thus to explore its dynamic mechanism on the formation is an important issue of the mountain-basin interaction. The Longmen Shan fold-and-thrust belt and its adjacent Sichuan basin located in the eastern margin of Tibetan Plateau, are one of the most-concerned regions of studying modern mountain-building and seismic process, and are also a natural laboratory of studying the dynamics of the formation and development of foreland basin. However, it still need further explore on the mechanics of the development of the Cenozoic foreland basin and thrust-belts in the western Sichuan Basin. The Longmen Shan thrust belt has experienced multi-stages of tectonics evolution, foreland basin formation and topography growth since Late Triassic, and whether the early formed basin architecture and large Mesozoic sedimentary basin taper can influence the formation and development of the Cenozoic foreland basin and thrust belts? To solve these issues, this project aim to focus on the Cenozoic foreland basin and internal crustal shortening structures in the western Sichuan basin, on the basis of growth critical wedge taper theory. We will reconstruct the shape of multi-phases of sedimentary basin tapers, the temporal-spatial distribution of crustal shortening and thrusting sequences, and analyze the control mechanism of Mesozoic sedimentary basin taper on the formation of Cenozoic foreland basins, and final explore the interaction between the tectonics geomorphology, stress field and dynamic propagation of foreland basin.

Alteration of immature sedimentary rocks on Earth and Mars. Recording Aqueous and Surface-atmosphere Processes

Energy Technology Data Exchange (ETDEWEB)

Cannon, Kenneth M. [Brown Univ., Providence, RI (United States); Mustard, John F. [Brown Univ., Providence, RI (United States); Salvatore, Mark R. [Arizona State Univ., Mesa, AZ (United States)

2015-03-05

The rock alteration and rind formation in analog environments like Antarctica may provide clues to rock alteration and therefore paleoclimates on Mars. Clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of Mars. Moreover, how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows. Here we characterize alteration in the chemically immature Carapace Sandstone from Antarctica, a terrestrial analog for martian sedimentary rocks. We employ a variety of measurements similar to those used on previous and current Mars missions. Laboratory techniques included bulk chemistry, powder X-ray diffraction (XRD), hyperspectral imaging and X-ray absorption spectroscopy. Through these methods we find that primary basaltic material in the Carapace Sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water–rock interaction. A thick orange rind is forming in current Antarctic conditions, superimposing this previous aqueous alteration signature. The rind exhibits a higher reflectance at visible-near infrared wavelengths than the rock interior, with an enhanced ferric absorption edge likely due to an increase in Fe³⁺ of existing phases or the formation of minor iron (oxy)hydroxides. This alteration sequence in the Carapace Sandstone results from decreased water–rock interaction over time, and weathering in a cold, dry environment, mimicking a similar transition early in martian history. This transition may be recorded in sedimentary rocks on Mars through a similar superimposition mechanism, capturing past climate changes at the hand sample scale. These results also suggest that basalt-derived sediments could have sourced significant volumes of hydrated minerals on early Mars due to their greater permeability compared with intact igneous rocks.

Potentiality if Rb-Sr method for dating the argillous sedimentary rocks

International Nuclear Information System (INIS)

Thomaz Filho, A.

1976-01-01

The potentiality of application Rb-Sr method in argillous sediments, using samples from paleozoic and mesozoic formation in brazilian sedimentaries basin was tested. Physical, chemistry and isotopic analysis of thirty eight samples were made in the laboratories of geochronology Research Center from the University of Sao Paulo. Four isochronic diagrams for the argillous sedimentary rocks were also proposed. (author)

Alteration of Sedimentary Clasts in Martian Meteorite Northwest Africa 7034

Science.gov (United States)

McCubbin, F. M.; Tartese, R.; Santos, A. R.; Domokos, G.; Muttik, N.; Szabo, T.; Vazquez, J.; Boyce, J. W.; Keller, L. P.; Jerolmack, D. J.;

The Behaviour of Fracture Growth in Sedimentary Rocks: A Numerical Study Based on Hydraulic Fracturing Processes

Directory of Open Access Journals (Sweden)

Lianchong Li

2016-03-01

Full Text Available To capture the hydraulic fractures in heterogeneous and layered rocks, a numerical code that can consider the coupled effects of fluid flow, damage, and stress field in rocks is presented. Based on the characteristics of a typical thin and inter-bedded sedimentary reservoir, China, a series of simulations on the hydraulic fracturing are performed. In the simulations, three points, i.e., (1 confining stresses, representing the effect of in situ stresses, (2 strength of the interfaces, and (3 material properties of the layers on either side of the interface, are crucial in fracturing across interfaces between two adjacent rock layers. Numerical results show that the hydrofracture propagation within a layered sequence of sedimentary rocks is controlled by changing in situ stresses, interface properties, and lithologies. The path of the hydraulic fracture is characterized by numerous deflections, branchings, and terminations. Four types of potential interaction, i.e., penetration, arrest, T-shaped branching, and offset, between a hydrofracture and an interface within the layered rocks are formed. Discontinuous composite fracture segments resulting from out-of-plane growth of fractures provide a less permeable path for fluids, gas, and oil than a continuous planar composite fracture, which are one of the sources of the high treating pressures and reduced fracture volume.

Study on flow and mass transport through fractured soft sedimentary rocks (Contact research)

International Nuclear Information System (INIS)

Shimo, Michito; Kumamoto, Sou; Maekawa, Keisuke

2007-03-01

It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground accurately. Though it is considered that the mass transport in sedimentary rock occurs in pores between grains mainly, fractures of sedimentary rock can be main paths. The objective of this study is to establish a conceptual model for flow and mass transport in fractured soft sedimentary rock. In previous study, a series of laboratory hydraulic and tracer tests and numerical analyses were carried out using sedimentary rock specimens obtained from Koetoi and Wakkanai formation. Single natural fractured cores and rock block specimen were used for the tests and analyses. The results indicated that the matrix diffusion played an important role for mass transport in the fractured soft sedimentary rocks. In this study, the following two tasks were carried out: (1) laboratory hydraulic and tracer experiments of rock cores of Koetoi and Wakkanai formation obtained at HDB-9, HDB-10 and HDB-11 boreholes and a rock block specimen, Wakkanai formation, obtained at an outcrop in the Horonobe area, (2) a numerical study on the conceptual model of flow and mass transport through fractured soft sedimentary rocks. Non-sorbing tracer experiments using naturally fractured cores and rock block specimens were carried out. Pottasium iodide was used as a tracer. The obtained breakthrough curves were interpreted and fitted by using a numerical simulator, and mass transport parameters, such as longitudinal dispersivity, matrix diffusion coefficient, transport aperture, were obtained. Mass transport simulations using a fracture network model, a continuum model and a double porosity model were performed to study the applicability of continuum model and double porosity model for transport in fractured sedimentary rock. (author)

Provenance and depositional age of metavolcano-sedimentary sequences of the Santa Terezinha de Goias, based on Sm-Nd and U-Pb zircon single grain

International Nuclear Information System (INIS)

Dantas, Ellton Luiz; Jost, Hardy; Fuck, Reinhardt A.; Brod, Jose Afonso; Pimentel, Marcio Martins; Meneses, Paulo Roberto

2001-01-01

Supracrustal rocks of the Santa Terezinha de Goias region, Central Brazil, presumably represent a southern extension of the Mara Rosa magmatic arc tectonically juxtaposed to Archean terrains and consist of a meta volcanic unit and a meta sedimentary unit. The aim of the paper is to present and discuss the first U-Pb and Sm-Nd data of rocks belonging to both units of that region. U-Pb data of zircons from a felsic meta volcanic rock inter layered with chlorite-rich schists (metandesites?) yield a concordant age of of 660 My, while the Sm-Nd model age of a variety of chlorite-schists indicate a juvenile age between 1.1 and 1.3 Ga. These data indicate that the meta volcanic rocks are Neo proterozoic in age and may be correlated with rocks of the Mara Rosa magmatic arc. On the other hand, the prevailing provenance of rocks belonging to the meta sedimentary unit indicate a Paleoproterozoic, or older, source. Thus, the deposition of both units are explained by means of the erosion of source-areas of variable age. (author)

Environmental and human impact on the sedimentary dynamic in the Rhone Delta subaquatic canyons (France-Switzerland)

Science.gov (United States)

Arantegui, A.; Corella, J. P.; Loizeau, J. L.; Anselmetti, F. S.; Girardclos, S.

2012-04-01

sediment dynamics during whether extreme flood events or mass-movements due to deltaic scarp failures. The active canyon shows a classic turbiditic system with frequent spillover processes in the canyon floor/levee complex. Geotechnical measurements, a decrease in the frequency of turbidites and a fining upward sequence along the levee suggest that erosion dominates sedimentation in the canyon floor, while sedimentation dominates in the rapid levee building-up process, with sedimentation rates that exceed 3cm/yr in the proximal areas. Therefore, mechanisms controlling the sedimentary evolution on the active canyon result in a complex interplay between erosion and sedimentation. Further research will provide a detailed evaluation of the human impact on sedimentary dynamic in the Rhone Delta subaquatic canyons.

Sedimentary facies analysis of the Mesozoic clastic rocks in Southern Peru (Tacna, 18°S): Towards a paleoenvironmental Redefinition and stratigraphic Reorganization

Science.gov (United States)

Alván, Aldo; Jacay, Javier; Caracciolo, Luca; Sánchez, Elvis; Trinidad, Inés

2018-07-01

The Mesozoic rocks of southern Peru comprise a Middle Jurassic to Early Cretaceous sedimentary sequence deposited during a time interval of approximately 34 Myr. In Tacna, these rocks are detrital and constitute the Yura Group (Callovian to Tithonian) and the Hualhuani Formation (Berriasian). Basing on robust interpretation of facies and petrographic analysis, we reconstruct the depositional settings of such units and provide a refined stratigraphic framework. Accordingly, nine types of sedimentary facies and six architectural elements are defined. They preserve the record of a progradational fluvial system, in which two styless regulated the dispersion of sediments: (i) a high-to moderate-sinuosity meandering setting (Yura Group), and a later (ii) incipient braided setting (Hualhuani Formation). The Yura Group (Callovian-Tithonian) represents the onset of floodplain deposits and lateral accretion of point-bar deposits sited on a semi-flat topography. Nonetheless, the progradational sequence was affected by at least two rapid marine ingressions occurred during Middle Callovian and Tithonian times. Such marine ingressions reveal the proximity of a shallow marine setting and incipient carbonate deposition. In response to increase in topographic gradient, the Hualhuani Formation (Berriasian) deposited as extensive multistory sandy channels. The mineralogy of the Mesozoic sediments suggests sediment supplies and intense recycling from a craton interior (i.e. Amazon Craton and/or plutonic sources) located eastward of the study area.

Microfacies characteristics, sedimentary environments and sequence stratigraphy of Upper Cretaceous deposits in northwest of Nehbandan (Basiran section

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Mohammad nabi Gorgij

2015-10-01

Full Text Available Introduction   The Basiran stratigraphic section is located about 160 km northwest of Nehbandan.The section was measured in detail at 59 06 30 N and 31 52 50 E. Nehbandan area with respect to fourfold geological subdivision of Iran is part of Central Iran that is located in the eastern flank of Lut Block which first time are studied by Stocklin et al.in 1972. Gorgij (2001 stratigraphically and paleontologically investigate Upper Cretaceous deposits in Mighan and Basiran sections. Upper Cretaceous deposits in in this area consists of 275m conglomerate,alternation of conglomerate-sandstone, sandy limestone -marl and limy marl, marl with intercalation of limestone-sandy limestone thin beds and medium-bedded to massive limestone. Microfacies analysis led to the recognition of 9 microfacies that are related to 5 belts; Coast, tidal flat, lagoon, shoal, shallow open marine and deep open marine environments. Main part of the section are deposited in the open marine environment that consist of marl,marly limestone and limestone. The doals of this study are : (1 describing and determining main carbonate and siliciclastic microfacies of late Cretaceous deposits (2 interpreting and providing depositional model for reconstruction of its paleoenvironmental setting based on microfacies characteristics (3 dividing the section based on lithostratigraphic principles and (4 recognizing a sequence stratigraphic model of this successions based on the vertical variation of facies,stratal key beds and stratal packing pattern.       Material and Method   The Basiran section as a complete stratigraphic section was measured and described. Up to 68 samples (indicated by KB1 to KB68 were collected and 170 thin sections are prepared. Based on field observations, sedimentological characteristics, parasequence stacking patterns, sequence boundary types and other key stratigraphical surfaces are identified and were obtained. Scheme of Dunham (1962 and Embry and Klovan

Microfacies characteristics, sedimentary environments and sequence stratigraphy of Upper Cretaceous deposits in northwest of Nehbandan (Basiran section

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Azadeh Bordbar

2015-09-01

Full Text Available   Introduction   The Basiran stratigraphic section is located about 160 km northwest of Nehbandan.The section was measured in detail at 59 06 30 N and 31 52 50 E. Nehbandan area with respect to fourfold geological subdivision of Iran is part of Central Iran that is located in the eastern flank of Lut Block which first time are studied by Stocklin et al.in 1972. Gorgij (2001 stratigraphically and paleontologically investigate Upper Cretaceous deposits in Mighan and Basiran sections. Upper Cretaceous deposits in in this area consists of 275m conglomerate,alternation of conglomerate-sandstone, sandy limestone -marl and limy marl, marl with intercalation of limestone-sandy limestone thin beds and medium-bedded to massive limestone. Microfacies analysis led to the recognition of 9 microfacies that are related to 5 belts Coast, tidal flat, lagoon, shoal, shallow open marine and deep open marine environments. Main part of the section are deposited in the open marine environment that consist of marl,marly limestone and limestone. The doals of this study are : (1 describing and determining main carbonate and siliciclastic microfacies of late Cretaceous deposits (2 interpreting and providing depositional model for reconstruction of its paleoenvironmental setting based on microfacies characteristics (3 dividing the section based on lithostratigraphic principles and (4 recognizing a sequence stratigraphic model of this successions based on the vertical variation of facies,stratal key beds and stratal packing pattern.       Material and Method   The Basiran section as a complete stratigraphic section was measured and described. Up to 68 samples (indicated by KB1 to KB68 were collected and 170 thin sections are prepared. Based on field observations, sedimentological characteristics, parasequence stacking patterns, sequence boundary types and other key stratigraphical surfaces are identified and were obtained. Scheme of Dunham (1962 and Embry

Atmospheric methane from organic carbon mobilization in sedimentary basins — The sleeping giant?

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Kroeger, K. F.; di Primio, R.; Horsfield, B.

2011-08-01

The mass of organic carbon in sedimentary basins amounts to a staggering 10 16 t, dwarfing the mass contained in coal, oil, gas and all living systems by ten thousand-fold. The evolution of this giant mass during subsidence and uplift, via chemical, physical and biological processes, not only controls fossil energy resource occurrence worldwide, but also has the capacity for driving global climate: only a tiny change in the degree of leakage, particularly if focused through the hydrate cycle, can result in globally significant greenhouse gas emissions. To date, neither climate models nor atmospheric CO 2 budget estimates have quantitatively included methane from thermal or microbial cracking of sedimentary organic matter deep in sedimentary basins. Recent estimates of average low latitude Eocene surface temperatures beyond 30 °C require extreme levels of atmospheric CO 2. Methane degassing from sedimentary basins may be a mechanism to explain increases of atmospheric CO 2 to values as much as 20 times higher than pre-industrial values. Increased natural gas emission could have been set in motion either by global tectonic processes such as pulses of activity in the global alpine fold belt, leading to increased basin subsidence and maturation rates in the prolific Jurassic and Cretaceous organic-rich sediments, or by increased magmatic activity such as observed in the northern Atlantic around the Paleocene-Eocene boundary. Increased natural gas emission would have led to global warming that was accentuated by long lasting positive feedback effects through temperature transfer from the surface into sedimentary basins. Massive gas hydrate dissociation may have been an additional positive feedback factor during hyperthermals superimposed on long term warming, such as the Paleocene-Eocene Thermal Maximum (PETM). As geologic sources may have contributed over one third of global atmospheric methane in pre-industrial time, variability in methane flux from sedimentary

Sedimentary records on the subduction-accretion history of the Russian Altai, northwestern Central Asian Orogenic Belt

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Chen, Ming; Sun, Min

2017-04-01

The Russian Altai, comprising the northern segment of the Altai-Mongolian terrane (AM) in the south, the Gorny Altai terrane (GA) in the north and the intervening Charysh-Terekta-Ulagan-Sayan suture zone, is a key area of the northwestern Central Asian Orogenic Belt (CAOB). A combined geochemical and detrital zircon study was conducted on the (meta-)sedimentary sequences from the Russian Altai to reveal the tectono-magmatic history of these two terranes and their amalgamation history, which in turn place constraints on the accretionary orogenesis and crustal growth in the CAOB. The Cambrian-Ordovician meta-sedimentary rocks from the northern AM are dominated by immature sediments possibly sourced from intermediate-felsic igneous rocks. Geochemical data show that the sediments were likely deposited in a continental arc-related setting. Zircons separated from these rocks are mainly 566-475 Ma and 1015-600 Ma old, comparable to the magmatic records of the Tuva-Mongolian terrane and surrounding island arcs in the western Mongolia. The similar source nature, provenance and depositional setting of these rocks to the counterparts from the Chinese Altai (i.e., the southern AM) imply that the whole AM possibly represents a coherent accretionary prism of the western Mongolia in the early Paleozoic rather than a Precambrian continental block with passive marginal deposition as previously thought. In contrast, the Cambrian to Silurian (meta-)sedimentary rocks from the GA are characterized by a unitary zircon population with ages of 640-470 Ma, which were potentially sourced from the Kuznetsk-Altai intra-oceanic island arc in the east of this terrane. The low abundance of 640-540 Ma zircons (5%) may attest that this arc was under a primitive stage in the late Neoproterozoic, when mafic igneous rocks dominated. However, the voluminous 530-470 Ma zircons (95%) suggest that this arc possibly evolved toward a mature one in the Cambrian to early Ordovician with increasing amount of

Application of MSS/LANDSAT images to the structural study of recent sedimentary areas: Campos Sedimentary Basin, Rio de Janeiro, Brazil

Science.gov (United States)

Parada, N. D. J. (Principal Investigator); Barbosa, M. P.

1983-01-01

Visual and computer aided interpretation of MSS/LANDSAT data identified linear and circular features which represent the ""reflexes'' of the crystalline basement structures in the Cenozoic sediments of the emergent part of the Campos Sedimentary Basin.

Pe do sedimentary sequence in late Quaternary section in Zarate, Argentina

International Nuclear Information System (INIS)

Tofalo, O.; Orgeira, M.; Alonso, M.; Ramos, A.

2007-01-01

Field geological features, grain-size, sand, silt and clay mineralogy, micromorphology, optically simulated luminiscence (OSL) ages have been used to reconstruct the pedosedimentary sequence in a late Quaternary section in Zarate, Buenos Aires province. Paleosols were developed on loess and four clear discontinuities in sedimentation and paleosols generation were observed. These discontinuities have determinated four units with different types of calcrete. The welded paleosols developed on unit C can be 1correlated and linked to the other ones outcropped in Baradero (Buenos Aires province) and Lozada (Cordoba province). These records probably span the equivalent of marine oxygen isotope stage (OIS) 5, the last interglacial stage before the present. The ground water and pedogenic calcretes and their association with smectite, illite and ferric oxide suggest dried climate than present one and strongly seasonality. (author)

Sorption and migration of neptunium in porous sedimentary materials

International Nuclear Information System (INIS)

Tanaka, Tadao; Mukai, Masayuki; Nakayama, Shinichi

2005-01-01

Column migration experiments of neptunium were conducted for porous sedimentary materials: coastal sand, tuffaceous sand, ando soil, reddish soil, yellowish soil and loess, and migration behavior, sorption mechanisms and chemical formation of Np were investigated. The migration behavior of Np in each material was much different each other, due to chemical formation in solution and/or sorption mechanism of Np. Mathematical models of different concepts were applied to the experimental results to interpret the sorption mechanism and the migration behavior. It can be concluded that both of instantaneous equilibrium sorption and sorption-desorption kinetics have to be considered to model the Np migration in sedimentary materials. (author)

A study about the long-term stability of sedimentary rock

International Nuclear Information System (INIS)

Yoshino, Naoto; Miyanomae, Shun-ichi; Inoue, Hiroyuki; Nashimoto, Yutaka

2005-02-01

In this paper, following two issues were examined and estimated, (1) the influence of near field condition factor to the dynamical behavior of sedimentary soft rock, (2) the long term estimation of the dynamical behavior considering the condition of Horonobe area. As the study about the influence of near field condition factor to the dynamical behavior of sedimentary soft rock, the thermal factor was focused on and the laboratory tests using test pieces which were sampled in Horonobe area were carried out under the water temperature were 20 degrees and 80 degrees. As a result, the time dependence parameter in variable-compliance-type constitutive-equation could be obtained. And comparison between creep property under 20 degrees and 80 degrees was conducted. In addition, the general properties of sedimentary soft rock under several conditions were identified by the survey of the literature. And the way how to confirm the dynamical properties of sedimentary soft rock with in-situ test were presented. For the study on the short-term and long-term stability of rock surrounding buffer materials, numerical simulations were carried out assuming several conditions. The direction of disposal tunnels and the ratio of rock strength by initial stress were estimated to be the main factor affecting the short-term stability of rock. Time dependency of rock and the stiffness of buffer material were estimated to be the main factor affecting the long-term stability of rock. (author)

Global Drainage Patterns to Modern Terrestrial Sedimentary Basins and its Influence on Large River Systems

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Nyberg, B.; Helland-Hansen, W.

2017-12-01

Long-term preservation of alluvial sediments is dependent on the hydrological processes that deposit sediments solely within an area that has available accomodation space and net subsidence know as a sedimentary basin. An understanding of the river processes contributing to terrestrial sedimentary basins is essential to fundamentally constrain and quantify controls on the modern terrestrial sink. Furthermore, the terrestrial source to sink controls place constraints on the entire coastal, shelf and deep marine sediment routing systems. In addition, the geographical importance of modern terrestrial sedimentary basins for agriculture and human settlements has resulted in significant upstream anthropogenic catchment modification for irrigation and energy needs. Yet to our knowledge, a global catchment model depicting the drainage patterns to modern terrestrial sedimentary basins has previously not been established that may be used to address these challenging issues. Here we present a new database of 180,737 global catchments that show the surface drainage patterns to modern terrestrial sedimentary basins. This is achieved by using high resolution river networks derived from digital elevation models in relation to newly acquired maps on global modern sedimentary basins to identify terrestrial sinks. The results show that active tectonic regimes are typically characterized by larger terrestrial sedimentary basins, numerous smaller source catchments and a high source to sink relief ratio. To the contrary passive margins drain catchments to smaller terrestrial sedimentary basins, are composed of fewer source catchments that are relatively larger and a lower source to sink relief ratio. The different geomorphological characteristics of source catchments by tectonic setting influence the spatial and temporal patterns of fluvial architecture within sedimentary basins and the anthropogenic methods of exploiting those rivers. The new digital database resource is aimed to help

Magnetic susceptibility evolution and sedimentary environments on carbonate platform sediments and atolls, comparison of the Frasnian from Belgium and Alberta, Canada

Science.gov (United States)

da Silva, Anne-Christine; Potma, Ken; Weissenberger, John A. W.; Whalen, Michael T.; Humblet, Marc; Mabille, Cédric; Boulvain, Frédéric

2009-02-01

Magnetic susceptibility (MS) measurements on carbonate rocks are considered as a proxy for impurities delivered to the carbonate environments. In the absence of strong climatic or tectonic variations, bulk MS values have been linked to sea level variations, because sea-level fall increases clastic supply and therefore increases in magnetic mineral deposition. In this paper we explore the relationship between the average magnitude of bulk MS, with shallowing-up sequences and facies evolution in different Devonian carbonate complexes. Similarities and differences between these parameters have been scrutinized in carbonate attached platform and detached platforms (mounds and/or atolls) from Belgium and Canada. In the carbonate attached platforms from Belgium and Canada, the MS patterns are directly related to depositional environment. Mean MS values increase from the most distal towards the most proximal facies and towards the top of the majority of fourth-order shallowing-up sequences. These trends are in agreement with theoretical background (MS increases with regression). In the Belgian detached platform, the average MS pattern generally shows an opposite behaviour to that observed in the attached carbonate platforms. Average MS decreases towards the most proximal facies and towards the top of a majority of the fourth-order shallowing-up sequences. This behaviour can be explained by the influence of sedimentary rate and water agitation during deposition. A high sedimentary rate will dilute the magnetic minerals in the atoll facies and the high water agitation during deposition may be expected to have prevented the deposition of the magnetic grains. So, the combination of these two effects will result in the observed low values in the atoll crown and lagoonal facies. In the Canadian detached platform, MS is mainly negative. This means that the limestones are very pure. The technique does not appear to be appropriate in these rocks. The variations of average MS

Natural radionuclides in major aquifer systems of the Parana sedimentary basin, Brazil

International Nuclear Information System (INIS)

Bonotto, Daniel Marcos

2011-01-01

This paper describes the natural radioactivity of groundwater occurring in sedimentary (Bauru and Guarani) and fractured rock (Serra Geral) aquifer systems in the Parana sedimentary basin, South America that is extensively used for drinking purposes, among others. The measurements of gross alpha and gross beta radioactivity as well the activity concentration of the natural dissolved radionuclides 40 K, 238 U, 234 U, 226 Ra, 222 Rn, 210 Po and 210 Pb were held in 80 tubular wells drilled in 21 municipalities located at Sao Paulo State and its border with Mato Grosso do Sul State in Brazil. Most of the gross alpha radioactivity data were below 1 mBq/L, whereas values exceeding the gross beta radioactivity detection limit of 30 mBq/L were found. The radioelement solubility in the studied systems varied according to the sequence radon>radium>other radionuclides and the higher porosity of sandstones relatively to basalts and diabases could justify the enhanced presence of dissolved radon in the porous aquifer. The implications of the data obtained in terms of standards established for defining the drinking water quality have also been discussed. The population-weighted average activity concentration for these radionuclides was compared to the guideline value of 0.1 mSv/yr for the total effective dose and discussed in terms of the choice of the dose conversion factors. - Highlights: → Integration of distinct radiometric data acquired in groundwaters. → Radiation dose in important hydrological resources in South America. → Contribution of 226 Ra for the more accentuated radiation dose in aquifers. → Dose factors for Rn and generation of values exceeding the maximum of 0.1 mSv/yr.

Natural radionuclides in major aquifer systems of the Parana sedimentary basin, Brazil

Energy Technology Data Exchange (ETDEWEB)

Bonotto, Daniel Marcos, E-mail: danielbonotto@yahoo.com.br [Departamento de Petrologia e Metalogenia, IGCE-Instituto de Geociencias e Ciencias Exatas, UNESP-Universidade Estadual Paulista Julio de Mesquita Filho, Av. 24-A, No. 1515 - CP 178, CEP 13506-900-Rio Claro, SP (Brazil)

2011-10-15

This paper describes the natural radioactivity of groundwater occurring in sedimentary (Bauru and Guarani) and fractured rock (Serra Geral) aquifer systems in the Parana sedimentary basin, South America that is extensively used for drinking purposes, among others. The measurements of gross alpha and gross beta radioactivity as well the activity concentration of the natural dissolved radionuclides {sup 40}K, {sup 238}U, {sup 234}U, {sup 226}Ra, {sup 222}Rn, {sup 210}Po and {sup 210}Pb were held in 80 tubular wells drilled in 21 municipalities located at Sao Paulo State and its border with Mato Grosso do Sul State in Brazil. Most of the gross alpha radioactivity data were below 1 mBq/L, whereas values exceeding the gross beta radioactivity detection limit of 30 mBq/L were found. The radioelement solubility in the studied systems varied according to the sequence radon>radium>other radionuclides and the higher porosity of sandstones relatively to basalts and diabases could justify the enhanced presence of dissolved radon in the porous aquifer. The implications of the data obtained in terms of standards established for defining the drinking water quality have also been discussed. The population-weighted average activity concentration for these radionuclides was compared to the guideline value of 0.1 mSv/yr for the total effective dose and discussed in terms of the choice of the dose conversion factors. - Highlights: > Integration of distinct radiometric data acquired in groundwaters. > Radiation dose in important hydrological resources in South America. > Contribution of {sup 226}Ra for the more accentuated radiation dose in aquifers. > Dose factors for Rn and generation of values exceeding the maximum of 0.1 mSv/yr.

Magnetostratigraphic dating of the Xiashagou Fauna and implication for sequencing the mammalian faunas in the Nihewan Basin, North China

NARCIS (Netherlands)

Liu, Ping; Deng, Chenglong; Li, Shihu; Cai, Shuhui; Cheng, Hongjiang; Wei, Qi; Zhu, Rixiang

2012-01-01

The Nihewan Basin sedimentary sequences in northern China are rich in mammalian fossil and Paleolithic sites, thus providing insights into our understanding of Quaternary land mammal biochronology and early human settlements in East Asia. Here we present high-resolution magnetostratigraphic results

Compaction and sedimentary basin analysis on Mars

Science.gov (United States)

Gabasova, Leila R.; Kite, Edwin S.

2018-03-01

Many of the sedimentary basins of Mars show patterns of faults and off-horizontal layers that, if correctly understood, could serve as a key to basin history. Sediment compaction is a possible cause of these patterns. We quantified the possible role of differential sediment compaction for two Martian sedimentary basins: the sediment fill of Gunjur crater (which shows concentric graben), and the sediment fill of Gale crater (which shows outward-dipping layers). We assume that basement topography for these craters is similar to the present-day topography of complex craters that lack sediment infill. For Gunjur, we find that differential compaction produces maximum strains consistent with the locations of observed graben. For Gale, we were able to approximately reproduce the observed layer orientations measured from orbiter image-based digital terrain models, but only with a >3 km-thick donut-shaped past overburden. It is not immediately obvious what geologic processes could produce this shape.

Sedimentary dynamics and high-frequency sequence stratigraphy of the southwestern slope of Great Bahama Bank

Science.gov (United States)

Wunsch, Marco; Betzler, Christian; Eberli, Gregor P.; Lindhorst, Sebastian; Lüdmann, Thomas; Reijmer, John J. G.

2018-01-01

New geophysical data from the leeward slope of Great Bahama Bank show how contour currents shape the slope and induce re-sedimentation processes. Along slope segments with high current control, drift migration and current winnowing at the toe of slope form a deep moat. Here, the slope progradation is inhibited by large channel incisions and the accumulation of large mass transport complexes, triggered by current winnowing. In areas where the slope is bathed by weaker currents, the accumulation of mass transport complexes and channel incision is rather controlled by the position of the sea level. Large slope failures were triggered during the Mid-Pleistocene transition and Mid-Brunhes event, both periods characterized by changes in the cyclicity or the amplitude of sea-level fluctuations. Within the seismic stratigraphic framework of third order sequences, four sequences of higher order were identified in the succession of the upper Pleistocene. These higher order sequences also show clear differences in function of the slope exposure to contour currents. Two stochastic models emphasize the role of the contour currents and slope morphology in the facies distribution in the upper Pleistocene sequences. In areas of high current influence the interplay of erosional and depositional processes form a complex facies pattern with downslope and along strike facies alterations. In zones with lower current influence, major facies alternations occur predominately in downslope direction, and a layer-cake pattern characterizes the along strike direction. Therefore, this study highlights that contour currents are an underestimated driver for the sediment distribution and architecture of carbonate slopes.

Estimating tectonic history through basin simulation-enhanced seismic inversion: Geoinformatics for sedimentary basins

Science.gov (United States)

Tandon, K.; Tuncay, K.; Hubbard, K.; Comer, J.; Ortoleva, P.

2004-01-01

A data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted. The approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters-but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin. Tectonic history has a first-order effect on the physical and chemical processes that govern the evolution of sedimentary basins. We demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction, transport, mechanical (RTM) basin model. We demonstrate the method by reconstructing the geothermal gradient. As thermal history strongly affects the rate of RTM processes operating in a sedimentary basin, variations in geothermal gradient history alter the present-day fluid pressure, effective stress, porosity, fracture statistics and hydrocarbon distribution. All these properties, in turn, affect the mechanical wave velocity and sediment density profiles for a sedimentary basin. The present-day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution, but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged. Using texture and fluid properties predicted by our Basin RTM simulator, we generate synthetic seismograms. Linear correlation using power spectra as an error measure and an efficient quadratic

Sedimentary environments and stratigraphy of the carbonate-silicilastic deposits of the Shirgesht Formation: implications for eustasy and local tectonism in the Kalmard Block, Central Iran

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reza Mousavi-Harami

2015-09-01

Full Text Available   Introduction   Sedimentological and sequence stratigraphic analysis providing insight into the main relationships between sequence architecture and stacking pattern, syn/post-depositional tectonics, and eustatic sea-level fluctuations (Gawthorpe and Leeder 2000 Zecchin et al. 2003, 2004 Carpentier et al. 2007. Relative variations in sea level are due to tectonic activity and eustasy. The Shirgesht Formation in the Kalmard Block of Central Iran provides a useful case study for to determine the processes responsible on internal architecture and stacking pattern of depositional sequences in a half-graben basin. In the Shirgesht Formation, siliciclastic and carbonate successions of the Kalmard Basin, the cyclic stratigraphic record is the result of the complex interaction of regional uplift, eustasy, local tectonics, sediment supply, and sedimentary processes (Bayet-Goll 2009, 2014 Hosseini-Barzi and Bayet-Goll 2009.     Material & Methods   Lower Paleozoic successions in Tabas and Kalmard blocks from Central Iran share the faunal and floral characteristics with other Gondwana sectors such as south-western Europe and north Africa–Middle East (Ghaderi et al. 2009. The geology of these areas was outlined by Ruttner et al. (1968 and by Bruton et al. (2004. The Cambrian-Middle Triassic strata in the Kalmard Block were deposited in a shallow water platform that possesses lithologic dissimilarities with the Tabas area (Aghanabati 2004. The occurrence of two active faults indicates clearly that Kalmard basin formed a mobile zone throughout the Paleozoic so that lithostratigraphic units show considerably contrasting facies in comparison with Tabas basin (Hosseini-Barzi and Bayet-Goll 2009 Bayet-Goll 2014 . The Shirgesht Formation in the Block Kalmard is mainly composed of carbonate-siliciclastic successions that disconformability overlain Kalmard Formation (attributed to Pre-Cambrian and is underlain by Gachal (Carboniferous or

Sedimentary environments and stratigraphy of the carbonate-silicilastic deposits of the Shirgesht Formation: implications for eustasy and local tectonism in the Kalmard Block, Central Iran

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aram bayetgoll

2015-10-01

Full Text Available Introduction   Sedimentological and sequence stratigraphic analysis providing insight into the main relationships between sequence architecture and stacking pattern, syn/post-depositional tectonics, and eustatic sea-level fluctuations (Gawthorpe and Leeder 2000; Zecchin et al. 2003, 2004; Carpentier et al. 2007. Relative variations in sea level are due to tectonic activity and eustasy. The Shirgesht Formation in the Kalmard Block of Central Iran provides a useful case study for to determine the processes responsible on internal architecture and stacking pattern of depositional sequences in a half-graben basin. In the Shirgesht Formation, siliciclastic and carbonate successions of the Kalmard Basin, the cyclic stratigraphic record is the result of the complex interaction of regional uplift, eustasy, local tectonics, sediment supply, and sedimentary processes (Bayet-Goll 2009, 2014; Hosseini-Barzi and Bayet-Goll 2009.     Material & Methods   Lower Paleozoic successions in Tabas and Kalmard blocks from Central Iran share the faunal and floral characteristics with other Gondwana sectors such as south-western Europe and north Africa–Middle East (Ghaderi et al. 2009. The geology of these areas was outlined by Ruttner et al. (1968 and by Bruton et al. (2004. The Cambrian-Middle Triassic strata in the Kalmard Block were deposited in a shallow water platform that possesses lithologic dissimilarities with the Tabas area (Aghanabati 2004. The occurrence of two active faults indicates clearly that Kalmard basin formed a mobile zone throughout the Paleozoic so that lithostratigraphic units show considerably contrasting facies in comparison with Tabas basin (Hosseini-Barzi and Bayet-Goll 2009; Bayet-Goll 2014 . The Shirgesht Formation in the Block Kalmard is mainly composed of carbonate-siliciclastic successions that disconformability overlain Kalmard Formation (attributed to Pre-Cambrian and is underlain by Gachal (Carboniferous or Rahdar (Devonian

Radon and its decay product activities in the magmatic area and the adjacent volcano-sedimentary Intrasudetic Basin

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D. Tchorz

2007-06-01

Full Text Available In the magmatic area of Sudetes covering the Karkonosze granite and adjacent volcano-sedimentary Intrasudetic Basin a study of atmospheric radon activity was performed by means of SSNTD Kodak LR-115. The study was completed by gamma spectrometric survey of eU and eTh determined by gamma activity of radon decay products 214Bi and 208Tl respectively. In the case of the western part of the Karkonosze granite area the radon decay products activity in the granitic basement was found to be as high as 343 Bq/kg for 214Bi and 496 Bq/kg for 208Tl respectively. Atmospheric radon content measured by means of Kodak LR115 track detector at the height of 1.5 m was found as high as 70 Bq/m3 in the regions, where no mining activities took place. However in the eastern part of the granitic massif in the proximity of abandoned uranium mine atmospheric radon content was found to be 6000 Bq/m3. In the case of sedimentary basin where sedimentary sequence of Carboniferous rocks has been penetrated by younger gases and fluids of volcanic origin uranium mineralization developed. The region known from its CO2 outburst during coal mining activity is characterized by good ventilation of the uranium enriched geological basement resulting in increased atmospheric radon activity being in average 72 Bq/m3. In the vicinity of coal mine tailing an increase up to 125 Bq/m3 can be observed. Seasonal variations of atmospheric radon content are influenced in agricultural areas by cyclic cultivation works (plough on soils of increased uranium content and in the case of post-industrial brownfields varying rates of radon exhalation from tailings due to different meteorological conditions.

Sedimentary Environments Offshore Norway - Palaeozoic to Recent

Energy Technology Data Exchange (ETDEWEB)

Martinsen, Ole J.; Dreyer, Tom [eds.

1999-07-01

The report includes the extended abstracts from the conference, 71 in number. The presentations discuss the sedimentary characteristics of the North Sea area and the the methods used in the research, a thorough knowledge of which is important for economic exploration of the oil and gas resources of the North Sea.

The complete genome of Zunongwangia profunda SM-A87 reveals its adaptation to the deep-sea environment and ecological role in sedimentary organic nitrogen degradation

Directory of Open Access Journals (Sweden)

Zhou Bai-Cheng

2010-04-01

Full Text Available Abstract Background Zunongwangia profunda SM-A87, which was isolated from deep-sea sediment, is an aerobic, gram-negative bacterium that represents a new genus of Flavobacteriaceae. This is the first sequenced genome of a deep-sea bacterium from the phylum Bacteroidetes. Results The Z. profunda SM-A87 genome has a single 5 128 187-bp circular chromosome with no extrachromosomal elements and harbors 4 653 predicted protein-coding genes. SM-A87 produces a large amount of capsular polysaccharides and possesses two polysaccharide biosynthesis gene clusters. It has a total of 130 peptidases, 61 of which have signal peptides. In addition to extracellular peptidases, SM-A87 also has various extracellular enzymes for carbohydrate, lipid and DNA degradation. These extracellular enzymes suggest that the bacterium is able to hydrolyze organic materials in the sediment, especially carbohydrates and proteinaceous organic nitrogen. There are two clustered regularly interspaced short palindromic repeats in the genome, but their spacers do not match any sequences in the public sequence databases. SM-A87 is a moderate halophile. Our protein isoelectric point analysis indicates that extracellular proteins have lower predicted isoelectric points than intracellular proteins. SM-A87 accumulates organic osmolytes in the cell, so its extracelluar proteins are more halophilic than its intracellular proteins. Conclusion Here, we present the first complete genome of a deep-sea sedimentary bacterium from the phylum Bacteroidetes. The genome analysis shows that SM-A87 has some common features of deep-sea bacteria, as well as an important capacity to hydrolyze sedimentary organic nitrogen.

Sedimentary condensation and authigenesis

Science.gov (United States)

Föllmi, Karl

2016-04-01

Most marine authigenic minerals form in sediments, which are subjected to condensation. Condensation processes lead to the formation of well individualized, extremely thin ( 100ky), and which experienced authigenesis and the precipitation of glaucony, verdine, phosphate, iron and manganese oxyhydroxides, iron sulfide, carbonate and/or silica. They usually show complex internal stratigraphies, which result from an interplay of sediment accumulation, halts in sedimentation, sediment winnowing, erosion, reworking and bypass. They may include amalgamated faunas of different origin and age. Hardgrounds may be part of condensed beds and may embody strongly condensed beds by themselves. Sedimentary condensation is the result of a hydrodynamically active depositional regime, in which sediment accumulation, winnowing, erosion, reworking and bypass are processes, which alternate as a function of changes in the location and intensity of currents, and/or as the result of episodic high-energy events engendered by storms and gravity flow. Sedimentary condensation has been and still is a widespread phenomenon in past and present-day oceans. The present-day distribution of glaucony and verdine-rich sediments on shelves and upper slopes, phosphate-rich sediments and phosphorite on outer shelves and upper slopes, ferromanganese crusts on slopes, seamounts and submarine plateaus, and ferromanganese nodules on abyssal seafloors is a good indication of the importance of condensation processes today. In the past, we may add the occurrence of oolitic ironstone, carbonate hardgrounds, and eventually also silica layers in banded iron formations as indicators of the importance of condensation processes. Besides their economic value, condensed sediments are useful both as a carrier of geochemical proxies of paleoceanographic and paleoenvironmental change, as well as the product of episodes of paleoceanographic and paleoenvironmental change themselves.

In-situ heating test in sedimentary soft rock. Phase 2

International Nuclear Information System (INIS)

Ikenoya, Takafumi; Takakura, Nozomu; Okada, Tetsuji; Sawada, Masataka; Hirano, Kouhei; Tani, Kazuo

2011-01-01

Various researches have been conducted on high level radioactive waste geological disposal in sedimentary soft rocks. It is noted that the long-term mechanical behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperatures or hydraulic conditions. Therefore, in-situ heater test was conducted in an underground cavern at a depth of 50 m for the purpose of improving thermo-hydro-mechanical coupled analysis code. This report presents the test result demonstrating the changes of temperature and strain distributions with time at the elevated temperature of the heater up to 90degC. (author)

Age and sedimentary record of inland eolian sediments in Lithuania, NE European Sand Belt

DEFF Research Database (Denmark)

Kalińska-Nartiša, Edyta; Thiel, Christine; Nartišs, Maris

2015-01-01

in any detail. The sedimentary structural-textural features are investigated and a chronology was derived using optically stimulated luminescence on both quartz and feldspar. The sedimentary structures and the rounding and surface characteristics of the quartz grains argue for a predominance of eolian...

Late Holocene sedimentary changes in floodplain and shelf environments of the Tagus River (Portugal)

NARCIS (Netherlands)

Vis, G.J.; Kasse, C.; Kroon, D.; Jung, S.J.A.; Zuur, H.; Prick, A.C.H.

2010-01-01

Sedimentary changes during the last ∼2500 years have been reconstructed from cored sedimentary records from the deltaic floodplain of the Lower Tagus Valley and the Tagus mudbelt on the continental shelf offshore Lisbon. We used a multi-proxy approach consisting of sedimentology, grainsize, pollen

Shallow Sedimentary Structure of the Brahmaputra Valley Constraint from Receiver Functions Analysis

Science.gov (United States)

Saikia, Sowrav; Chopra, Sumer; Baruah, Santanu; Singh, Upendra K.

2017-01-01

In this study, receiver functions from ten Broadband seismograph stations on Cenozoic sediment formations of Brahmaputra valley and its neighboring region in northeastern part of India are determined. Receiver function traces from this region show delay in peak by 1-2.5 s and associated minor peaks with the direct P-phase peak. Based on such observation, we try to image sedimentary structure of the Brahmaputra valley plain, adjacent Shillong plateau and Himalayan foredeep region. An adapted hybrid global waveform inversion technique has been applied to extract sedimentary basin structure beneath each site. The sedimentary cover of the basin is about 0.5-6.5 km thick across the valley, 0.5-1.0 km on Shillong plateau and 2.0-5.0 km in nearby foredeep region. We have found that sedimentary thickness increases from SW to NE along the Brahmaputra valley and towards the Eastern Himalayan syntaxes. The estimated sediment thickness and S wave velocity structure agree well with the results of previous active source, gravity, and deep borehole studies carried out in this region. The thick crustal low velocity sediment cover in Brahmaputra valley is expected to amplify ground motions during earthquakes and therefore important for seismic hazard assessment of the region.

High frequency of phylogenetically diverse reductive dehalogenase-homologous genes in deep subseafloor sedimentary metagenomes

Directory of Open Access Journals (Sweden)

Mikihiko eKawai

2014-03-01

Full Text Available Marine subsurface sediments on the Pacific margin harbor diverse microbial communities even at depths of several hundreds meters below the seafloor (mbsf or more. Previous PCR-based molecular analysis showed the presence of diverse reductive dehalogenase gene (rdhA homologs in marine subsurface sediment, suggesting that anaerobic respiration of organohalides is one of the possible energy-yielding pathways in the organic-rich sedimentary habitat. However, primer-independent molecular characterization of rdhA has remained to be demonstrated. Here, we studied the diversity and frequency of rdhA homologs by metagenomic analysis of five different depth horizons (0.8, 5.1, 18.6, 48.5 and 107.0 mbsf at Site C9001 off the Shimokita Peninsula of Japan. From all metagenomic pools, remarkably diverse rdhA-homologous sequences, some of which are affiliated with novel clusters, were observed with high frequency. As a comparison, we also examined frequency of dissimilatory sulfite reductase genes (dsrAB, key functional genes for microbial sulfate reduction. The dsrAB were also widely observed in the metagenomic pools whereas the frequency of dsrAB genes was generally smaller than that of rdhA-homologous genes. The phylogenetic composition of rdhA-homologous genes was similar among the five depth horizons. Our metagenomic data revealed that subseafloor rdhA homologs are more diverse than previously identified from PCR-based molecular studies. Spatial distribution of similar rdhA homologs across wide depositional ages indicates that the heterotrophic metabolic processes mediated by the genes can be ecologically important, functioning in the organic-rich subseafloor sedimentary biosphere.

Pore water colloid properties in argillaceous sedimentary rocks

Energy Technology Data Exchange (ETDEWEB)

Degueldre, Claude, E-mail: c.degueldre@lancaster.ac.uk [Engineering Department, University of Lancaster, LA1 4YW Lancaster (United Kingdom); ChiAM & Institute of Environment, University of Geneva, 1211 Genève 4, Swizerland (Switzerland); Earlier, NES, Paul Scherrer Institute, 5232 Villigen (Switzerland); Cloet, Veerle [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland)

2016-11-01

The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks. As a result of field campaigns, groundwater colloid concentrations are investigated on the basis of their size distribution quantified experimentally using single particle counting techniques. The colloid properties are estimated considering data gained from analogue hydrogeochemical systems ranging from mylonite features in crystalline fissures to sedimentary formations. The colloid concentrations were analysed as a function of the alkaline and alkaline earth element concentrations. Laboratory batch results on clay colloid generation from compacted pellets in quasi-stagnant water are also reported. Experiments with colloids in batch containers indicate that the size distribution of a colloidal suspension evolves toward a common particle size distribution independently of initial conditions. The final suspension size distribution was found to be a function of the attachment factor of the colloids. Finally, calculations were performed using a novel colloid distribution model based on colloid generation, aggregation and sedimentation rates to predict under in-situ conditions what makes colloid concentrations and size distributions batch- or fracture-size dependent. The data presented so far are compared with the field and laboratory data. The colloid occurrence, stability and mobility have been evaluated for the water of the considered potential host rocks. In the pore water of the considered sedimentary host rocks, the clay

Excess europium content in Precambrian sedimentary rocks and continental evolution

Science.gov (United States)

Jakes, P.; Taylor, S. R.

1974-01-01

It is proposed that the europium excess in Precambrian sedimentary rocks, relative to those of younger age, is derived from volcanic rocks of ancient island arcs, which were the source materials for the sediments. Precambrian sedimentary rocks and present-day volcanic rocks of island arcs have similar REE patterns, total REE abundances, and excess Eu, relative to the North American shale composite. The present upper crustal REE pattern, as exemplified by that of sediments, is depleted in Eu, relative to chondrites. This depletion is considered to be a consequence of development of a granodioritic upper crust by partial melting in the lower crust, which selectively retains europium.

Imaging the Moho beneath Sedimentary Basins: A Comparative Study of Virtual Deep Seismic Sounding (VDSS) and P Wave Receiver Functions (PRF)

Science.gov (United States)

Liu, T.; Klemperer, S. L.; Yu, C.; Ning, J.

2017-12-01

In the past decades, P wave receiver functions (PRF) have been routinely used to image the Moho, although it is well known that PRFs are susceptible to contamination from sedimentary multiples. Recently, Virtual Deep Seismic Sounding (VDSS) emerged as a novel method to image the Moho. However, despite successful applications of VDSS on multiple datasets from different areas, how sedimentary basins affect the waveforms of post-critical SsPmp, the Moho reflection phase used in VDSS, is not widely understood. Here, motivated by a dataset collected in the Ordos plateau, which shows distinct effects of sedimentary basins on SsPmp and Pms waveforms, we use synthetic seismograms to study the effects of sedimentary basins on SsPmp and Pms, the phases used in VDSS and PRF respectively. The results show that when the sedimentary thickness is on the same order of magnitude as the dominant wavelength of the incident S wave, SsPmp amplitude decreases significantly with S velocity of the sedimentary layer, whereas increasing sedimentary thickness has little effect in SsPmp amplitude. Our explanation is that the low S velocity layer at the virtual source reduces the incident angle of S wave at the free surface, thus decreases the S-to-P reflection coefficient at the virtual source. In addition, transmission loss associated with the bottom of sedimentary basins also contributes to reducing SsPmp amplitude. This explains not only our observations from the Ordos plateau, but also observations from other areas where post-critical SsPmp is expected to be observable, but instead is too weak to be identified. As for Pms, we observe that increasing sedimentary thickness and decreasing sedimentary velocities both can cause interference between sedimentary multiples and Pms, rendering the Moho depths inferred from Pms arrival times unreliable. The reason is that although Pms amplitude does not vary with sedimentary thickness or velocities, as sedimentary velocities decrease and thickness

Fluid flow and sediment transport in evolving sedimentary basins

Science.gov (United States)

Swenson, John Bradley

This thesis consists of three studies that focus on groundwater flow and sediment transport in evolving sedimentary basins. The first study considers the subsurface hydrodynamic response to basin-scale transgression and regression and its implications for stratiform ore genesis. I demonstrate that the transgressive sequence focuses marginward-directed, compaction-driven discharge within a basal aquifer during progradation and deposition of the overlying regressive sequence, isolates the basal aquifer from overlying flow systems, and serves as a chemical sink for metal-bearing brines. In the second study, I develop a new theory for the shoreline response to subsidence, sediment supply, and sea level. In this theory, sediment transport in a fluvio-deltaic basin is formally equivalent to heat transfer in a two-phase (liquid and isothermal solid) system: the fluvial system is analogous to a conduction-dominated liquid phase, the shoreline is the melting front, and the water depth at the delta toe is equivalent to the latent heat of fusion. A natural consequence of this theory is that sediment-starved basins do not possess an equilibrium state. In contrast to existing theories, I do not observe either strong phase shifting or attenuation of the shoreline response to low-frequency eustatic forcing; rather, shoreline tracks sea level over a spectrum of forcing frequencies, and its response to low-frequency forcing is amplified relative to the high-frequency response. For the third study, I use a set of dimensionless numbers from the previous study as a mathematical framework for providing a unified treatment of existing stratigraphic theories. In the limit of low-amplitude eustatic forcing, my study suggests that strong phase shifting between shoreline and sea level is a consequence of specifying the sedimentation rate at the shoreline; basins free of this constraint do not develop strong phase shifts.

The investigation of sedimentary facies and stacking pattern in the Mulid River (Southeastern Qayen

Directory of Open Access Journals (Sweden)

Marzieh Fayazi Borujeni

2017-03-01

Full Text Available Introduction In the most gravel bed rivers, particle size exponentially decreases to the downstream. The study of particle size fining trend to the downstream and determination of the effective processes on it along the recent rivers is accomplished in the different parts of Iran. The river sedimentary facies are deposited in the channel and overbank areas and they are provided important information about sedimentary environment and deposition rate, the extent and development of the river channel and floodplain. These sedimentary facies that are deposited in the different depositional conditions have been achieved from variations of flow regime and/ or variation in the depositional environment in the large scale. The aim of this study is to investigate of the particle size variations and the effective controllers of fining trend to downstream, to determine of the important factors in creating sedimentary discontinuities and to study of the sedimentary facies, architectural elements, determination of depositional model and some paleohydraulic parameters of river. The Mulid River catchment with elongated shape is located in 120 km of southeast Qayen in the Southern Khorasan Province, in the 33̊ 24ʹ 44.3ʺ to 33̊ 35ʹ 11.4ʺ east latitude and 59̊ 56ʹ 42.5ʺ to 59̊ 58ʹ 44ʺ north longitude. According to the geological classification of Iran, this basin is a part of the East Iran flysch and mélange belt that is located in the east of the Lut Block.  Materials and Methods  In order to sedimentological studies, 30 sediment samples unsystematically were collected from upstream to downstream and from about 20 cm depth of the main channel bottom of river (with 30 km long. The granulometry analysis of the studied samples were achieved using the dry sieving method with 0.5 φ intervals and weight percent of gravel, sand and mud size particles were estimated. The sediment naming is done using Folk (1980 classification and the estimation of sorting

Scotland's forgotten carbon: a national assessment of mid-latitude fjord sedimentary carbon stocks

Science.gov (United States)

Smeaton, Craig; Austin, William E. N.; Davies, Althea L.; Baltzer, Agnes; Howe, John A.; Baxter, John M.

2017-12-01

Fjords are recognised as hotspots for the burial and long-term storage of carbon (C) and potentially provide a significant climate regulation service over multiple timescales. Understanding the magnitude of marine sedimentary C stores and the processes which govern their development is fundamental to understanding the role of the coastal ocean in the global C cycle. In this study, we use the mid-latitude fjords of Scotland as a natural laboratory to further develop methods to quantify these marine sedimentary C stores on both the individual fjord and national scale. Targeted geophysical and geochemical analysis has allowed the quantification of sedimentary C stocks for a number of mid-latitude fjords and, coupled with upscaling techniques based on fjord classification, has generated the first full national sedimentary C inventory for a fjordic system. The sediments within these mid-latitude fjords hold 640.7 ± 46 Mt of C split between 295.6 ± 52 and 345.1 ± 39 Mt of organic and inorganic C, respectively. When compared, these marine mid-latitude sedimentary C stores are of similar magnitude to their terrestrial equivalents, with the exception of the Scottish peatlands, which hold significantly more C. However, when area-normalised comparisons are made, these mid-latitude fjords are significantly more effective as C stores than their terrestrial counterparts, including Scottish peatlands. The C held within Scotland's coastal marine sediments has been largely overlooked as a significant component of the nation's natural capital; such coastal C stores are likely to be key to understanding and constraining improved global C budgets.

Microbial mat-induced sedimentary structures in siliciclastic sediments

Indian Academy of Sciences (India)

This paper addresses macroscopic signatures of microbial mat-related structures within the. 1.6Ga-old Chorhat Sandstone ... Sandstone differentiated in facies superposed one over the other and their respective structural assemblages (b). may be ..... within the classification of primary sedimentary struc- tures; J. Sed. Res.

Modern sedimentary processes along the Doce river adjacent continental shelf

Directory of Open Access Journals (Sweden)

Valéria da Silva Quaresma

Full Text Available In areas of the continental shelf where sediment supply is greater than the sediment dispersion capacity, an extensive terrigenous deposits and consequently submerged deltas can be formed. The Eastern Brazilian shelf is characterized by the occurrence of river feed deltas in between starving coasts. Herein, modern sedimentary processes acting along the Doce river adjacent continental shelf are investigated. The main objective was to understand the shelf sediment distribution, recognizing distinct sedimentary patterns and the major influence of river sediment discharge in the formation of shelf deposits. The study used 98 surficial samples that were analyzed for grain size, composition and bulk density. Results revealed 3 distinct sectors: south - dominated by mud fraction with a recent deposition from riverine input until 30 m deep and from this depth bioclastic sands dominate; central north - sand mud dominated, been recognized as a bypass zone of resuspended sediment during high energy events; and north - relict sands with high carbonate content. The modern sedimentation processes along the Doce river continental shelf is dominated by distinct sedimentary regimes, showing a strong fluvial influence associated with wave/wind induced sediment dispersion and a carbonate regime along the outer shelf. These regimes seem to be controlled by the distance from the river mouth and bathymetric gradients.

Sources and distribution of sedimentary organic matter along the Andong salt marsh, Hangzhou Bay

Science.gov (United States)

Yuan, Hong-Wei; Chen, Jian-Fang; Ye, Ying; Lou, Zhang-Hua; Jin, Ai-Min; Chen, Xue-Gang; Jiang, Zong-Pei; Lin, Yu-Shih; Chen, Chen-Tung Arthur; Loh, Pei Sun

2017-10-01

Lignin oxidation products, δ13C values, C/N ratios and particle size were used to investigate the sources, distribution and chemical stability of sedimentary organic matter (OM) along the Andong salt marsh located in the southwestern end of Hangzhou Bay, China. Terrestrial OM was highest at the upper marshes and decreased closer to the sea, and the distribution of sedimentary total organic carbon (TOC) was influenced mostly by particle size. Terrestrial OM with a C3 signature was the predominant source of sedimentary OM in the Spartina alterniflora-dominated salt marsh system. This means that aside from contributions from the local marsh plants, the Andong salt marsh received input mostly from the Qiantang River and the Changjiang Estuary. Transect C, which was situated nearer to the Qiantang River mouth, was most likely influenced by input from the Qiantang River. Likewise, a nearby creek could be transporting materials from Hangzhou Bay into Transect A (farther east than Transect C), as Transect A showed a signal resembling that of the Changjiang Estuary. The predominance of terrestrial OM in the Andong salt marsh despite overall reductions in sedimentary and terrestrial OM input from the rivers is most likely due to increased contributions of sedimentary and terrestrial OM from erosion. This study shows that lower salt marsh accretion due to the presence of reservoirs upstream may be counterbalanced by increased erosion from the surrounding coastal areas.

Scotland's forgotten carbon: a national assessment of mid-latitude fjord sedimentary carbon stocks

Directory of Open Access Journals (Sweden)

C. Smeaton

2017-12-01

Full Text Available Fjords are recognised as hotspots for the burial and long-term storage of carbon (C and potentially provide a significant climate regulation service over multiple timescales. Understanding the magnitude of marine sedimentary C stores and the processes which govern their development is fundamental to understanding the role of the coastal ocean in the global C cycle. In this study, we use the mid-latitude fjords of Scotland as a natural laboratory to further develop methods to quantify these marine sedimentary C stores on both the individual fjord and national scale. Targeted geophysical and geochemical analysis has allowed the quantification of sedimentary C stocks for a number of mid-latitude fjords and, coupled with upscaling techniques based on fjord classification, has generated the first full national sedimentary C inventory for a fjordic system. The sediments within these mid-latitude fjords hold 640.7 ± 46 Mt of C split between 295.6 ± 52 and 345.1 ± 39 Mt of organic and inorganic C, respectively. When compared, these marine mid-latitude sedimentary C stores are of similar magnitude to their terrestrial equivalents, with the exception of the Scottish peatlands, which hold significantly more C. However, when area-normalised comparisons are made, these mid-latitude fjords are significantly more effective as C stores than their terrestrial counterparts, including Scottish peatlands. The C held within Scotland's coastal marine sediments has been largely overlooked as a significant component of the nation's natural capital; such coastal C stores are likely to be key to understanding and constraining improved global C budgets.

Chemistry of decomposition of freshwater wetland sedimentary organic material during ramped pyrolysis

Science.gov (United States)

Williams, E. K.; Rosenheim, B. E.

2011-12-01

Ramped pyrolysis methodology, such as that used in the programmed-temperature pyrolysis/combustion system (PTP/CS), improves radiocarbon analysis of geologic materials devoid of authigenic carbonate compounds and with low concentrations of extractable authochthonous organic molecules. The approach has improved sediment chronology in organic-rich sediments proximal to Antarctic ice shelves (Rosenheim et al., 2008) and constrained the carbon sequestration potential of suspended sediments in the lower Mississippi River (Roe et al., in review). Although ramped pyrolysis allows for separation of sedimentary organic material based upon relative reactivity, chemical information (i.e. chemical composition of pyrolysis products) is lost during the in-line combustion of pyrolysis products. A first order approximation of ramped pyrolysis/combustion system CO2 evolution, employing a simple Gaussian decomposition routine, has been useful (Rosenheim et al., 2008), but improvements may be possible. First, without prior compound-specific extractions, the molecular composition of sedimentary organic matter is unknown and/or unidentifiable. Second, even if determined as constituents of sedimentary organic material, many organic compounds have unknown or variable decomposition temperatures. Third, mixtures of organic compounds may result in significant chemistry within the pyrolysis reactor, prior to introduction of oxygen along the flow path. Gaussian decomposition of the reaction rate may be too simple to fully explain the combination of these factors. To relate both the radiocarbon age over different temperature intervals and the pyrolysis reaction thermograph (temperature (°C) vs. CO2 evolved (μmol)) obtained from PTP/CS to chemical composition of sedimentary organic material, we present a modeling framework developed based upon the ramped pyrolysis decomposition of simple mixtures of organic compounds (i.e. cellulose, lignin, plant fatty acids, etc.) often found in sedimentary

Amino acids in the sedimentary humic and fulvic acids

Digital Repository Service at National Institute of Oceanography (India)

Sardessai, S.

acids in the coastal Arabian Sea sediments: whereas amino acids content of fulvic acids was lower than that of humic acids in the coastal sediments of Bay of Bengal. Slope sedimentary humic acids were relatively enriched in amino acids as compared...

Planning of the in-situ creep test in sedimentary soft rocks under high temperature

International Nuclear Information System (INIS)

Takakura, Nozomu; Yoshikawa, Kazuo; Okada, Tetsuji; Sawada, Masataka; Tani, Kazuo; Takeda, Kayo

2007-01-01

Research has been conducted on underground facilities for energy storage and waste disposal in sedimentary soft rocks. One of the research topics is that the long-term mechanical behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperatures or hydraulic conditions. Therefore, it is necessary to develop a method for evaluating the long-term stability of caverns in sedimentary soft rocks as influenced by changes in the external environment. This report presents the plan of field creep test for the purpose to establish the evaluation method of long-term stability of caverns in soft rocks. A series of field creep test is performed to study the influence of high temperature in an underground facility at a depth of 50 meters. (author)

Sedimentary Facies Mapping Based on Tidal Channel Network and Topographic Features

Science.gov (United States)

Ryu, J. H.; Lee, Y. K.; Kim, K.; Kim, B.

2015-12-01

Tidal flats on the west coast of Korea suffer intensive changes in their surface sedimentary facies as a result of the influence of natural and artificial changes. Spatial relationships between surface sedimentary facies distribution and benthic environments were estimated for the open-type Ganghwa tidal flat and semi closed-type Hwangdo tidal flat, Korea. In this study, we standardized the surface sedimentary facies and tidal channel index of the channel density, distance, thickness and order. To extract tidal channel information, we used remotely sensed data, such as those from the Korea Multi-Purpose Satellite (KOMPSAT)-2, KOMPSAT-3, and aerial photographs. Surface sedimentary facies maps were generated based on field data using an interpolation method.The tidal channels in each sediment facies had relatively constant meandering patterns, but the density and complexity were distinguishable. The second fractal dimension was 1.7-1.8 in the mud flat, about 1.4 in the mixed flat, and about 1.3 in the sand flat. The channel density was 0.03-0.06 m/m2 in the mud flat and less than 0.02 m/m2 in the mixed and sand flat areas of the two test areas. Low values of the tidal channel index, which indicated a simple pattern of tidal channel distribution, were identified at areas having low elevation and coarse-grained sediments. By contrast, high values of the tidal channel index, which indicated a dendritic pattern of tidal channel distribution, were identified at areas having high elevation and fine-grained sediments. Surface sediment classification based on remotely sensed data must circumspectly consider an effective critical grain size, water content, local topography, and intertidal structures.

Sea-floor morphology and sedimentary environments in western Block Island Sound, offshore of Fishers Island, New York

Science.gov (United States)

McMullen, Katherine Y.; Poppe, Lawrence J.; Danforth, William W.; Blackwood, Dann S.; Winner, William G.; Parker, Castle E.

2015-01-01

Multibeam-bathymetric and sidescan-sonar data, collected by the National Oceanic and Atmospheric Administration in a 114-square-kilometer area of Block Island Sound, southeast of Fishers Island, New York, are combined with sediment samples and bottom photography collected by the U.S. Geological Survey from 36 stations in this area in order to interpret sea-floor features and sedimentary environments. These interpretations and datasets provide base maps for studies on benthic ecology and resource management. The geologic features and sedimentary environments on the sea floor are products of the area’s glacial history and modern processes. These features include bedrock, drumlins, boulders, cobbles, large current-scoured bathymetric depressions, obstacle marks, and glaciolacustrine sediments found in high-energy sedimentary environments of erosion or nondeposition; and sand waves and megaripples in sedimentary environments characterized by coarse-grained bedload transport. Trawl marks are preserved in lower energy environments of sorting and reworking. This report releases the multibeam-bathymetric, sidescan-sonar, sediment, and photographic data and interpretations of the features and sedimentary environments in Block Island Sound, offshore Fishers Island.

A process-sedimentary framework for characterizing recent and ancient sabkhas

Science.gov (United States)

Handford, C.R.

1981-01-01

The discovery of sabkha environments during the 1960's, marked the beginning of Recent evaporite sedimentological studies and their perception as models for facies analysis. However, variation among Recent sabkhas, though recognized by the geologic community, has not been duly addressed, which has resulted in overuse of the Trucial Coast model in comparative sedimentological studies. Knowledge of the dominant physical processes which determine sabkha morphology, and of the sedimentary response to those processes, can lead to a fundamental understanding of a sabkha's origin and of how it differs from other sabkhas. Physical processes thought to be most important (besides evaporation) include those operative under: (1) marine-; (2) fluvial-lacustrine-; and (3) eolian-dominated conditions. Dominance of one or more of these in the proper settings give rise to marine coastal sabkhas, continental playas, and interdune sabkhas. Sedimentary responses to dominant physical processes lead to the development of sabkhas consisting of a combination of either: (1) terrigenous clastics; (2) carbonate-sulfate (anhydrite-gypsum) minerals; or (3) soluble salts (halite, sylvite, polyhalite, etc.). Sediment characterization can also allow discrimination of the range or compositional variety in, for example, coastal sabkhas. Where applied to the stratigraphic record, this classification system may help unravel the sedimentary history of an ancient sabkha system, and a determination of the dominant physical processes that ruled its development. ?? 1981.

Characteristics of vertical seismic motions and qp-values in sedimentary layers

International Nuclear Information System (INIS)

Tohdo, Masanobu; Hatori, Toshiaki; Chiba, Osamu; Takahashi, Katsuya; Takemura, Masayuki; Tanaka, Hideo.

1995-01-01

Using seismic records observed in 4 borehole arrays, characteristics of vertical seismic motions in sedimentary layers are investigated. The results are as follows. 1) P-waves having intensive effect to vertical component are propagating within sedimentary layers even after the S-wave onset time (S-wave part). 2) Frequency dependent Q-values for P-waves (Qp) in Tertiary sediment layers obtained from the optimal analyses to spectral ratios have the tendency to be identical with Q-values for S-waves (Qs) with the same wavelength. 3) Observed vertical motions in upper ground can be simulated by the multiple reflection theory of P-waves based on the optimized velocities and Q-values. (author)

[Distribution Characteristics of Sedimentary Pigments in the Changjiang Estuary and Zhe-Min Coast and its Implications].

Science.gov (United States)

Li, Dong; Yao, Peng; Zhao, Bin; Wang, Jin-peng; Pan, Hui-hui

2015-08-01

Compositions and contents of sedimentary pigments were examined using high performance liquid chromatography in order to discuss the spatial distributions of phytoplankton primary production, phytoplankton functional type and the preservation efficiency of phytoplankton pigments and their influencing factors. The results showed that: chloropigments [Chlorins, including chlorophyll-a (Chl-a) and pheopigments (Pheo-a), such as pheophytin-a (PHtin-a), pheophorbide-a (PHide-a), pPheophytin-a (pPHtin-a), sterol chlorin esters (SCEs) and carotenol chlorin esters (CCEs)] were the major type of sedimentary pigments. The nutrients inputs from Changjiang Diluted Water and upwelling in the Zhe-Min coastal mud area were the major cause for the patchy distribution with high sedimentary chloropigment contents. Carotenoid contents showed no trending changes and exhibited high values in the Changjiang Estuary and Zhe-Min Coasts. Based on the relative proportions of each diagnostic carotenoid to the total diagnostic carotenoids in the sediments, the relative contributions of diatoms, dinoflagellates, prymnesiophytes, prasinophytes, cryptophytes and cyanobacterias in the phytoplankton fuctional types were 48.8% +/- 17.4%, 10.7% +/- 11.5%, 8.1% +/- 7.2%, 18.6% +/- 8.2%, 9.4% +/- 6.4% and 4.3% +/- 3.2%, respectively. The preference for external environmental conditions (e.g., nutrient level and water salinity) was the main cause for the decreasing trends of diatoms and dinoflagellates proportions and the increasing trends of prasinophytes, cryptophytes and cyanobacterias seawards. Based on the spatial distribution of Chl-a/Pheo-a ratios, the higher preservation efficiencies of sedimentary pigments in the coastal regions (e.g., outer edge of maximum turbidity zone in the Changjiang Estuary, mouth of the Hangzhou Bay and upwelling region in the Zhe-Min Coast) were mainly due to the higher sedimentation rate and seasonal occurrences of hypoxia in bottom water, and these regions with

Micro-analysis by U-Pb method using LAM-ICPMS and its applications for the evolution of sedimentary basins: the example from Brasilia Belt; Micro-analise pelo metodo U-Pb usando LAM-CIPMS e suas aplicacoes para a evolucao de bacias sedimentares: o exemplo da faixa Brasilia

Energy Technology Data Exchange (ETDEWEB)

Pimentel, Marcio Martins; Matteini, Massimo; Junges, Sergio Luiz; Giustina, Maria Emilia Schutesky Della; Dantas, Elton Luiz; Buhn, Bernhard, E-mail: marcio@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias; Rodrigues, Joseneusa Brilhante [Servico Geologico do Brasil (CPRM), Brasilia, DF (Brazil)

2015-07-01

The U-Pb geochronological method using LAM-MC-ICPMS represents an important tool to investigate the geological evolution of sedimentary basins, as well as its geochronology, through the determination of upper limits for the depositional ages of detrital sedimentary rocks. The method has been applied in the Geochronology Laboratory of the Universidade de Brasilia, and in this study, a brief review of the provenance data for the sediments of the Neoproterozoic Brasilia Belt is presented and their significance for the evolution of the orogen is discussed. The results indicate that the Paranoa and Canastra Groups represent passive margin sequences formed along the western margin of the Sao Francisco-Congo continent. The Vazante Group presents similar provenance patterns, although Sm-Nd isotopic results suggest that its upper portions had contributions from younger (Neoproterozoic) sources, possibly from the Neoproterozoic Goias Magmatic Arc. On the other hand, metasediments of the Araxa and Ibia groups contain an important proportion of material derived from Neoproterozoic sources, demonstrating that they represent syn-orogenic basins. The provenance pattern of the Bambui Group is marked by an important Neoproterozoic component, showing that it constitutes a sedimentary sequence which is younger than 600 Ma, representing a foreland basin to the Brasilia Belt. (author)

Seasonal variations and sources of sedimentary organic carbon in Tokyo Bay

International Nuclear Information System (INIS)

Kubo, Atsushi; Kanda, Jota

2017-01-01

Total organic carbon (TOC), total nitrogen (TN) contents, their stable C and N isotope ratio (δ 13 C and δ 15 N), and chlorophyll a ([Chl a] sed ) of surface sediments were investigated monthly to identify the seasonal variations and sources of organic matter in Tokyo Bay. The sedimentary TOC (TOC sed ) and TN (TN sed ) contents, and the sedimentary δ 13 C and δ 15 N (δ 13 C sed and δ 15 N sed ) values were higher in summer than other seasons. The seasonal variations were controlled by high primary production in the water column and hypoxic water in the bottom water during summer. The fraction of terrestrial and marine derived organic matter was estimated by Bayesian mixing model using stable isotope data and TOC/TN ratio. Surface sediments in Tokyo Bay are dominated by marine derived organic matter, which accounts for about 69 ± 5% of TOC sed . - Highlights: • High values of sedimentary organic carbon and nitrogen were observed in summer. • Surface sediments in Tokyo Bay were dominated by marine derived organic matter which was estimated by Bayesian mixing model. • The most amount of terrestrial POC was deposited and degraded in Tokyo Bay before being discharged to the open ocean.

Electrical resistivity dynamics beneath a fractured sedimentary bedrock riverbed in response to temperature and groundwater–surface water exchange

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C. M. Steelman

2017-06-01

Full Text Available Bedrock rivers occur where surface water flows along an exposed rock surface. Fractured sedimentary bedrock can exhibit variable groundwater residence times, anisotropic flow paths, and heterogeneity, along with diffusive exchange between fractures and rock matrix. These properties of the rock will affect thermal transients in the riverbed and groundwater–surface water exchange. In this study, surface electrical methods were used as a non-invasive technique to assess the scale and temporal variability of riverbed temperature and groundwater–surface water interaction beneath a sedimentary bedrock riverbed. Conditions were monitored at a semi-daily to semi-weekly interval over a full annual period that included a seasonal freeze–thaw cycle. Surface electromagnetic induction (EMI and electrical resistivity tomography (ERT methods captured conditions beneath the riverbed along a pool–riffle sequence of the Eramosa River in Canada. Geophysical datasets were accompanied by continuous measurements of aqueous specific conductance, temperature, and river stage. Time-lapse vertical temperature trolling within a lined borehole adjacent to the river revealed active groundwater flow zones along fracture networks within the upper 10 m of rock. EMI measurements collected during cooler high-flow and warmer low-flow periods identified a spatiotemporal riverbed response that was largely dependent upon riverbed morphology and seasonal groundwater temperature. Time-lapse ERT profiles across the pool and riffle sequence identified seasonal transients within the upper 2 and 3 m of rock, respectively, with spatial variations controlled by riverbed morphology (pool versus riffle and dominant surficial rock properties (competent versus weathered rock rubble surface. While the pool and riffle both exhibited a dynamic resistivity through seasonal cooling and warming cycles, conditions beneath the pool were more variable, largely due to the formation of river

TRANSGRESSIVE SEQUENCES ON FORELAND MARGINS: A CASE STUDY OF THE NEOGENE CENTRAL GUADALQUIVIR BASIN, SOUTHERN SPAIN

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J. GABRIEL PENDÓN

2004-07-01

Full Text Available The Guadalquivir foreland basin, located between the Iberian basement northward and the Betic orogen to the South, represents the western sector of the earlier foredeep basin of the Betic Cordillera. Along the northern foreland margin, the sedimentary fill of this basin includes a Tortonian Basal Transgressive Complex (BTC, composed of five internal sequences bounded by transgressive surfaces. Two main parts are distinguished within each sequence: the lower transgressive lag deposits, and the upper stillstand/prograding sediments. Three facies associations were distinguished within this stratigraphic succession along the central sector of this basin margin: unfossiliferous conglomerates and coarse-grained sands (A, fossiliferous conglomerates and coarse-grained sands (B, and yellow medium-coarse-grained fossiliferous sands (C. A fourth facies association (D: blue silty marlstones and shales overlies the BTC. Deposits of alluvial sediments (facies association A and shallow-marine/foreshore sediments (facies association C, were recurrently interrupted by transgressive pulses (facies associations B and C. Every pulse is recorded by an erosional, cemented sandy-conglomerate bar with bivalves (Ostreidae, Isognomon, balanids, gastropods and other marine bioclasts; or their transgressive equivalents. The lateral facies changes in each individual sequence of the BTC are related to: (1 the influence on the northern foreland margin of the tectonic activity of the southern orogenic margin; (2 the palaeorelief formed by irregularities of the substrate which controls the sediment dispersal; and (3 the evolution stages of the sedimentary systems. 

Fracture propagation through a layered shale and limestone sequence at Nash Point, South Wales: Implications on the development of fracture networks in layered sequences

Science.gov (United States)

Forbes Inskip, N.; Meredith, P. G.; Gudmundsson, A.

2017-12-01

While considerable effort has been expended on the study of fracture propagation in rocks in recent years, our understanding of how fractures propagate through sedimentary rocks composed of layers with different mechanical and elastic properties remains poor. Yet the mechanical layering is a key parameter controlling the propagation of fractures in sedimentary sequences. Here we report measurements of the contrasting properties of the Lower Lias at Nash Point, South Wales, which comprises a sequence of interbedded shale and limestone layers, and how those properties influence fracture propagation. The static Young's modulus (Estat) of both rock types has been measured parallel and normal to bedding. The shale is highly anisotropic, with Estat varying from 2.4 GPa, in the bedding-normal orientation, to 7.9 GPa, in the bedding-parallel orientation, yielding an anisotropy of 107%. By contrast the limestone has a very low anisotropy of 8%, with Estat values varying from 28.5 GPa, in the bedding-normal orientation, to 26.3 GPa in the bedding-parallel orientation. It follows that for a vertical fracture propagating in this sequence the modulus contrast is by a factor of about 12. This is important because the contrast in elastic properties is a key factor in controlling whether fractures arrest, deflect, or propagate across interfaces between layers in a sequence. Preliminary numerical modelling results (using a finite element modelling software) of induced fractures at Nash Point demonstrate a rotation of the maximum principal compressive stress across interfaces but also the concentration of tensile stress within the more competent (high Estat) limestone layers. The tensile strength (σT), using the Brazil-disk technique, and fracture toughness (KIc), using the semi-circular bend methodology, of both rock types have been measured. Measurements were made in the three principal orientations relative to bedding, Arrester, Divider, and Short-Transverse, and also at 15�

Sea-floor morphology and sedimentary environments in southern Narragansett Bay, Rhode Island

Science.gov (United States)

McMullen, Katherine Y.; Poppe, Lawrence J.; Blackwood, Dann S.; Nardi, Matthew J.; Andring, Matthew A.

2015-09-09

Multibeam echosounder data collected by the National Oceanic and Atmospheric Administration along with sediment samples and still and video photography of the sea floor collected by the U.S. Geological Survey were used to interpret sea-floor features and sedimentary environments in southern Narragansett Bay, Rhode Island, as part of a long-term effort to map the sea floor along the northeastern coast of the United States. Sea-floor features include rocky areas and scour depressions in high-energy environments characterized by erosion or nondeposition, and sand waves and megaripples in environments characterized by coarse-grained bedload transport. Two shipwrecks are also located in the study area. Much of the sea floor is relatively featureless within the resolution of the multibeam data; sedimentary environments in these areas are characterized by processes associated with sorting and reworking. This report releases bathymetric data from the multibeam echosounder, grain-size analyses of sediment samples, and photographs of the sea floor and interpretations of the sea-floor features and sedimentary environments. It provides base maps that can be used for resource management and studies of topics such as benthic ecology, contaminant inventories, and sediment transport.

Depositional environment and sedimentary of the basinal sediments in the Eibiswalder Bucht (Radl Formation and Lower Eibiswald Beds), Miocene Western Styrian Basin, Austria

Science.gov (United States)

Stingl, K.

1994-12-01

The Eibiswald Bucht is a small subbasin of the Western Styrian Basin exposing sediments of Lower Miocene age. In the past the entire sequence exposed in the Eibiswalder Bucht has been interpreted as being of fluvial/lacustrine origin; here, results are presented of detailed sedimentological investigations that lead to a revision of this concept. The lowermost siliciclastic sedimentary unit of the Eibiswalder Bucht sequence is the Radl Formation. It is overlain by the Eibiswald Beds, which are subdivided into the Lower, Middle and Upper Eibiswald Beds. The Radl Formation and the Lower Eibiswald Beds are interpreted as a fan delta complex deposited along NNW-SSE striking faults. Based on the sedimentary facies this fan delta can be subdivided into a subaerial alluvial fan facies group, a proximal delta facies group and a distal delta/prodelta facies group. The Radl Formation comprises the alluvial fan and proximal delta facies groups, the Lower Eibiswald Beds the distal delta/prodelta facies group. The alluvial fan and the proximal delta consist of diverse deposits of gravelly flows. The distal delta/prodelta consists of wave-reworked, bioturbated, low density turbidites intercalated with minor gravelly mass flows. The prodelta can be regarded as as the basin facies of the small and shallow Eibiswalder Bucht, where marine conditions prevailed. The basin was probably in part connected with the Eastern Styrian Basin, the contemporary depositional environment of the Styrian Schlier (mainly turbiditic marine offshore sediments in the Eastern Styrian Basin). Analysis of the clast composition, in conjunction with the paleotransport direction of the coarse delta mass flows of the Radl Formation, shows that the source rocks were exclusively crystalline rocks ranging from greenschists to eclogites.

The Mesoproterozoic volcano-sedimentary Serra do Itaberaba Group of the Central Ribeira Belt, Sao Paulo State, Brazil: implications for the age of the overlying Sao Roque Group

International Nuclear Information System (INIS)

Juliani, Caetano; Hackspacher, Peter; Fetter, Allen Hutchenson; Dantas, Elton Luiz

2000-01-01

One of the fundamental problems to understanding the evolution of volcano-sedimentary sequences in southeastern Brazil is constraining their depositional ages. Brasiliano tectonic and metamorphic either obscured or destroyed primary features, such as unconformities, as well as other geologic relationships. This problem is exemplified by the Serra do Itaberaba and Sao Roque groups, where the lack of data about the timing of their deposition has prevented resolution of proposed one-and two-stage geotectonic/depositional models. Recent U-Pb zircon data obtained from metavolcanic rocks in the Sao Roque Group indicate that it was deposited between 628 and 607 Ma. New U-Pb zircon data of 1395± 10 Ma for a metandesite in the basal Morro da Pedra Preta Formation (Serra do Itaberaba Group) indicate the maximum age for the beginning of the deposition of the pelites overlying MORB-like basalt. A metarhyolite of the upper unit, the Nhangucu Formation, contains two zircon populations. One yielded an age of 619 ±3 Ma, which defines the crystallization age of the rock, and the other an age of 1449 ±3 Ma, interpreted as inherited xenocrystal grains from older units of the Serra do Itaberaba Group. The younger metarhyolite was affected only by the S 2 foliation, generated during the Brasiliano orogenesis, whereas the Middle Proterozoic metavolcano-sedimentary sequence records additional metamorphic and deformational events, confirming the presence of two different geotectonic cycles. (author)

Cover sequences at the northern margin of the Antongil Craton, NE Madagascar

Science.gov (United States)

Bauer, W.; Walsh, G.J.; De Waele, B.; Thomas, Ronald J.; Horstwood, M.S.A.; Bracciali, L.; Schofield, D.I.; Wollenberg, U.; Lidke, D.J.; Rasaona, I.T.; Rabarimanana, M.H.

2011-01-01

The island of Madagascar is a collage of Precambrian, generally high-grade metamorphic basement domains, that are locally overlain by unmetamorphosed sedimentary rocks and poorly understood low-grade metasediments. In the Antalaha area of NE Madagascar, two distinct cover sequences rest on high-grade metamorphic and igneous basement rocks of the Archaean Antongil craton and the Neoproterozoic Bemarivo belt. The older of these two cover sequences, the Andrarona Group, consists of low-grade metasedimentary rocks. The younger sequence, the newly defined Ampohafana Formation, consists of unmetamorphosed sedimentary rocks. The Andrarona Group rests on Neoarchaean granites and monzogranites of the Antongil craton and consists of a basal metagreywacke, thick quartzites and an upper sequence of sericite-chlorite meta-mudstones, meta-sandstones and a volcaniclastic meta-sandstone. The depositional age of the volcaniclastic meta-sandstone is constrained in age by U–Pb laser-ablation ICP-MS analyses of euhedral zircons to 1875 ± 8 Ma (2σ). Detrital zircons of Archaean and Palaeoproterozoic age represent an input from the Antongil craton and a newly defined Palaeoproterozoic igneous unit, the Masindray tonalite, which underlies the Andrarona Group, and yielded a U–Pb zircon age of 2355 ± 11 Ma (2σ), thus constraining the maximum age of deposition of the basal part of the Andrarona Group. The Andrarona Group shows a low-grade metamorphic overprint in the area near Antalaha; illite crystallinity values scatter around 0.17°Δ2Θ CuKα, which is within the epizone. The Ampohafana Formation consists of undeformed, polymict conglomerate, cross-bedded sandstone, and red mudstone. An illite crystallinity value of >0.25°Δ2Θ CuKα obtained from the rocks is typical of the diagenetic zone. Occurrences of rhyodacite pebbles in the Ampohafana Formation and the intrusion of a basaltic dyke suggest a deposition in a WSW-ENE-trending graben system during the opening of the Indian

Mantle convective support, drainage patterns and sedimentary flux: Examples from the West Africa passive margin

Science.gov (United States)

Lodhia, B. H.; Roberts, G. G.; Fraser, A.; Goes, S. D. B.; Fishwick, S.; Jarvis, J.

2017-12-01

Sedimentary flux measurements, regional subsidence patterns, inversion of drainage patterns, tomographic models and simple isostatic calculations are combined to constrain the history of sub-plate support of North West Africa. Backstripping of 8 commercial wells and mapping of 53,000 line-km of 2D seismic reflection data show that rapid ( 0.03 mm a-1) Neogene-Recent subsidence occurred in a 500 x 500 km region offshore Mauritania. 0.4-0.8 km of water-loaded subsidence occurred in the center of the basin during the last 23 Ma. Salt withdrawal, thin-skinned tectonics, glacio-eustasy and flexure of the lithosphere due to the emplacement of Cape Verde cannot explain the timing or magnitude of this phase of subsidence. Instead, conversion of shear wave velocities into temperature and simple isostatic calculations indicate that asthenospheric temperatures determine bathymetry from Cape Verde to West Africa. Our results indicate that asthenospheric flow from Cape Verde to Mauritania generated a bathymetric gradient of 1/300 at a wavelength of 103 km during the last 23 Ma. We explore the relationship between uplift and erosion onshore and measured solid sedimentary flux offshore. First, the history of sedimentary flux to the margin was determined by depth-converting and decompacting biostratigraphically-dated isopachs. Compaction and velocity errors, determined using check-shot data, were propagated into calculated sedimentary flux history. Solid-sedimentary flux rates of 0.2-0.1+0.2 ×103 km3 /Ma between 23.8-5.6 Ma, and 1.9-1.4+2.0 ×103 km3 /Ma from 5.6-0 Ma are observed. Secondly, a calibrated stream power erosional model was used to invert 14700 river profiles for a history of regional uplift rate. Incision rates were integrated along best-fitting theoretical river profiles to predict sedimentary flux at mouths of the rivers draining NW Africa. Our predicted history of sedimentary flux increases in two stages towards the present-day, in agreement with our offshore

Pore water colloid properties in argillaceous sedimentary rocks.

Science.gov (United States)

Degueldre, Claude; Cloet, Veerle

2016-11-01

The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks. As a result of field campaigns, groundwater colloid concentrations are investigated on the basis of their size distribution quantified experimentally using single particle counting techniques. The colloid properties are estimated considering data gained from analogue hydrogeochemical systems ranging from mylonite features in crystalline fissures to sedimentary formations. The colloid concentrations were analysed as a function of the alkaline and alkaline earth element concentrations. Laboratory batch results on clay colloid generation from compacted pellets in quasi-stagnant water are also reported. Experiments with colloids in batch containers indicate that the size distribution of a colloidal suspension evolves toward a common particle size distribution independently of initial conditions. The final suspension size distribution was found to be a function of the attachment factor of the colloids. Finally, calculations were performed using a novel colloid distribution model based on colloid generation, aggregation and sedimentation rates to predict under in-situ conditions what makes colloid concentrations and size distributions batch- or fracture-size dependent. The data presented so far are compared with the field and laboratory data. The colloid occurrence, stability and mobility have been evaluated for the water of the considered potential host rocks. In the pore water of the considered sedimentary host rocks, the clay

Geological storage of carbon dioxide: the role of sedimentary basins

International Nuclear Information System (INIS)

Gunter, W.D.; Bachu, S.

2001-01-01

Sedimentary basins, occuring throughout the world, are thick piles of geologically deposited sediments that are the hosts for fossil fuel deposits. They may become even more important in the future if their large storage capacity is utilized for disposing of carbon dioxide. Sedimentary basins are dynamic, in the sense that they have an intricate plumbing system defined by the location of high and low permeability strata that control the flow of fluids throughout the basins and define 'hydrogeological' traps. The most secure type of hydrogeological trapping is found in oil and gas reservoirs in the form of 'structural' or 'stratigraphic' traps, termed 'closed' hydrogeological traps which have held oil and gas for millions of years. Obviously, these would be very attractive for CO 2 storage due to their long history of containment. A second type of hydrogeological trapping has been recognized in aquifers of sedimentary basins that have slow flow rates. The pore space in such 'open' hydrogeological traps is usually filled with saline ground or formation water. A volume of CO 2 injected into a deep open hydrogeological trap can take over a million years to travel updip to reach the surface and be released to the atmosphere. Although the capacity of structural/stratigraphic traps for CO 2 storage is small relative to open hydrogeological traps in deep sedimentary basins, they are likely to be used first as they are known to be secure, having held oil and gas for geological time. As the capacity of closed traps is exhausted and more is learned about geochemical trapping, the large storage capacity available in open hydrogeological traps will be utilized where security of the geological storage of CO 2 can be enhanced by geochemical reactions of the CO 2 with basic silicate minerals to form carbonates. Potential short circuits to the surface through faults or abandoned wells must be located and their stability evaluated before injection of CO 2 . In any event, a

Sedimentary architecture and depositional evolution of the Quaternary coastal plain of Maricá, Rio de Janeiro, Brazil

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André Luiz Carvalho da Silva

Full Text Available The coastal geomorphology of Maricá (Rio de Janeiro state is characterized by a large lagoon and by two sandy barriers that confine a series of small isolated chain-like lagoons. Data collected from ground-penetrating radar and boreholes from the central coastal plain of Maricá provided information on the sedimentary architecture and evolution of this area in the Quaternary. Six lithological units were identified comprising three depositional sequences limited by erosional surfaces, related to barrier-lagoon systems that migrated onshore, offshore, and longshore, giving rise to a sedimentary deposit 25 m thick or more. The data reveal a retrograding barrier overlying a basal mud unit which rests in unconformity upon Precambrian basement, thus characterizing an important Pleistocene transgression. A second Pleistocene barrier of 45,000 cal years BP migrated over a lagoonal mud unit (48,000-45,000 cal years BP reaching over the previous barrier. A progradational phase followed due to a fall of sea level. A long interval of erosion of the barrier created an unconformity that represents the Pleistocene-Holocene boundary. A beachrock in nearby Itaipuaçu, 100 m offshore from the present-day beach, dated as 8,500 cal years BP marks the onset of Holocene sedimentation due to gradually rising sea level, which continued until at about 5,000 years ago. This promoted the retrogradation of the barrier-lagoon system. A brief episode of progradation is observed as a series of paleobeach scarps. Today's rising sea level is causing the retrogradation of the barrier.

Drilling rate for the Cerro Prieto stratigraphic sequence

Energy Technology Data Exchange (ETDEWEB)

Prian C, R.

1981-01-01

Drilling practice at the field has been modified in several ways as better information is being obtained. The stratigraphic sequence of the area is made up of three sedimentary rock units of deltaic origin having different densities. These units have been named non-consolidated, semi-consolidated, and consolidated rocks; the thermal reservoirs are located in the latter. To investigate how the drilling rates are affected by the three rock units, plots of drilling advance versus time were made for a large number of wells. A typical plot is shown and drilling rates are practically constant in three different zones; that is, the drilling rate has only two breaks or changes in slope.

Sedimentary characteristics of samples collected from some submarine canyons

NARCIS (Netherlands)

Bouma, Arnold H.

Oriented rectangular cores of 20.3 × 30.5 cm and 45.7 cm high have been collected in a number of submarine canyons off southern California (U.S.A.) and off the southern tip of Baja California (Mexico) for a detailed study of their sedimentary structures. By applying several methods, mainly X-ray

How to find the sedimentary archive of fluvial pollution in a bedrock-confined river reach

Science.gov (United States)

Elznicova, Jitka; Matys Grygar, Tomas; Kiss, Timea; Lelkova, Tereza; Balogh, Marton; Sikora, Martin

2016-04-01

, dated the sediments by dendrology and OSL dating, and performed in situ XRF analysis of sediment cores. The data show that the downstream head of the bar is the oldest and most of fine sediments (mostly sand, minor silt) of the bar material have been historically polluted by Pb mining. The sedimentary sequences, most valuable for reconstruction of recent pollution, were found in the side channel where the fill the representing the last ca 150 years pollution history (Hg and U). The body of the bar has been formed earlier. According to our hypothesis the bar originated as a direct consequence of historical mining in the nearby Jachymov Ore Region. The use of lateral fluvial deposits as a sedimentary archive definitely requires intensive application of fluvial geomorphology. Vice versa, pollution patterns will allow delineating areas, in particular the bar bank and inlet to the side channel, where intensive reworking (erosion/redeposition) occurred as documented by the microtopography and woody debris.

Engineering Geological Properties of Oil-Contaminated Granitic and Meta sedimentary Soils

International Nuclear Information System (INIS)

Zulfahmi Ali Rahman; Umar Hamzah; Noorulakma Ahmad

2011-01-01

Hydrocarbon is a light-non aqueous phase liquid or known as LNAPL. It poses environmental hazard if accidentally spilled out into the soil and water systems as a result of its insoluble nature in water. LNAPL component infiltrates into soil through pore spaces and afloat at the top of groundwater level. Some of this hydrocarbon would trap and clog within the voids, difficult to remove and costly to clean. The occurrence of hydrocarbon in the soil definitely degraded the behaviour of soils in terms of engineering properties. This study aimed to investigate the engineering properties of oil-contaminated soil for two different residual soils originally developed from in-situ weathering of granitic and meta sedimentary rocks. The physical characterisations of the soil were determined including particle size distribution, specific gravity test and x-ray diffraction (XRD). The engineering parameters for the contaminated and uncontaminated soils were Atterberg limits, compaction and soil shear strength (UU tests). The amounts of hydrocarbon added to soil were varied at 0 %, 4 %, 8 %, 12 % and 16 % of dried weight of soil samples. The results from the particle size distribution analysis showed that residual soil from granitic rock comprises of 38 % sand, 33 % silt and 4 % clay while meta sedimentary soil consists of 4 % sand, 43 % silt dan 29 % clay. The mean values of specific gravity for the granitic and meta sedimentary soils were 2.56 and 2.61, respectively. The types of minerals present in granitic soil sample were quartz, kaolinite and gibbsite while meta sedimentary soil consists of quartz and kaolinite. The Atterberg limits value decreased as a result of increasing amount of added hydrocarbon into the soil. A similar behavior was observed with the values of maximum dry density and optimum water content with increasing hydrocarbon content. The overall unconsolidated undrained shear strength, C u showed a decreasing trend with the increase in hydrocarbon content

Integrated techniques to evaluate the features of sedimentary rocks of archaeological areas of Sicily

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Maria Brai

2004-02-01

Full Text Available Sicily includes a great variety of lithologies, giving a high complexity to the geologic landscape. Their prevalent lithology is sedimentary. It is well known that rocks of sedimentary origin, compared with metamorphic and volcanic deposits, can be relatively soft and hence fairly easy to model. Nevertheless, this workability advantage is a drawback for Cultural Heritage applications. In fact, these materials show a high porosity, with pore-size distributions that lead to deterioration through absorption of water. In this paper, several sedimentary rocks used in historical Cultural Heritage items of Sicily, from "Magna Graecia" to nowadays, are classified for mineralogical features, chemical composition, and for porosity. Particularly, some samples collected in quarries relevant to the archaeological sites of 41 Agrigento, Segesta and Selinunte will be considered and characterized using integrated techniques (XRD, XRF, NMR and CT. Data on samples obtained in laboratory will be compared with the relevant values measured in situ on monuments of historical-cultural interest of the quoted archaeological places.

In-situ heater test in sedimentary soft rocks under high temperature (Phase I)

International Nuclear Information System (INIS)

Ikenoya, Takafumi; Takakura, Nozomu; Okada, Tetsuji; Sawada, Masataka; Hirano, Kouhei; Tani, Kazuo

2008-01-01

Various researches have been conducted on high level radioactive waste geological disposal in sedimentary soft rocks. It's noted that the long-term mechanical behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperatures or hydraulic conditions. Therefore, in-situ heater test was conducted in an underground cavern at a depth of 50 meters for the purpose of improving thermo-hydro-mechanical coupled analysis code. This report presents the test result demonstrating the changes of temperature and strain distributions with time at the elevated temperature of the heater up to 40 degrees Celsius. (author)

Aeolian sedimentary processes at the Bagnold Dunes, Mars: Implications for modern dune dynamics and sedimentary structures in the aeolian stratigraphic record of Mars

Science.gov (United States)

Ewing, Ryan C.; Bridges, Nathan T.; Sullivan, Rob; Lapotre, Mathieu G. A.; Fischer, Woodward W.; Lamb, Mike P.; Rubin, David M.; Lewis, Kevin W.; Gupta, Sanjeev

2016-04-01

Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under Martian conditions. In-situ observations of sand dunes (informally called the Bagnold Dunes) by Curiosity Rover in Gale Crater, Mars provide the first opportunity to make observations of dunes from the grain-to-dune scale thereby filling the gap in knowledge between theory and orbital observations and refining our understanding of the martian aeolian stratigraphic record. We use the suite of cameras on Curiosity, including Navigation Camera (Navcam), Mast Camera (Mastcam) and Mars Hand Lens Imager (MAHLI), to make observations of the Bagnold Dunes. Measurements of sedimentary structures are made where stereo images are available. Observations indicate that structures generated by gravity-driven processes on the dune lee slopes, such as grainflow and grainfall, are similar to the suite of aeolian sedimentary structures observed on Earth and should be present and recognizable in Mars' aeolian stratigraphic record. Structures formed by traction-driven processes deviate significantly from those found on Earth. The dune hosts centimeter-scale wind ripples and large, meter-scale ripples, which are not found on Earth. The large ripples migrate across the depositional, lee slopes of the dune, which implies that these structures should be present in Mars' stratigraphic record and may appear similar to compound-dune stratification.The Mars Science Laboratory Curiosity Rover Team is acknowledged for their support of this work.

FEATURES OF GEODEFORMATION CHANGES OF NEAR SURFACE SEDIMENTARY ROCKS

Directory of Open Access Journals (Sweden)

I. A. Larionov

2016-11-01

Full Text Available The results of investigations of the deformation process in the near surface sedimentary rocks, which has been carried out in a seismically active region of Kamchatka peninsular since 2007,are presented. The peculiarity of the experiments on the registration of geodeformations is the application of a laser deformograph-interferometer constructed according to the Michelson interferometer scheme.

Tectono-stratigraphy of the Lower Cretaceous Syn-rift Succession in Bongor Basin, Chad: Insights into Structural Controls on Sedimentary Infill of a Continental Rift

Science.gov (United States)

Chen, C.; Ji, Y.; Wei, X.; An, F.; Li, D.; Zhu, R.

2017-12-01

In a rift basin, the dispersal and deposition of sediments is significantly influenced by the paleo-topography, which is highly controlled by the evolution and interaction of normal faults in different scales. To figure out the impact of faults evolution and topographic elements towards sedimentary fillings, we investigated the Lower Cretaceous syn-rift package in Bongor Basin, south of Chad Republic. Constrained with 2D and 3D seismic data, core data and logging information, a sequence stratigraphy architecture and a variety of depositional systems are recognized, including fan delta, braided delta, sub-lacustrine fan and lacustrine system. We also studied the spatial distribution and temporal evolution of clastic depositional systems of the syn-rift complex, and valuable insights into structural controls of sequence architectures and depositional systems are provided. During the evolution of rift basin, marginal structures such as relay ramps and strike-slipping boundary transfer fault are major elements that influence the main sediments influx points. Release faults in the hanging-wall could form a differential evolution pattern for accommodation, and effect the deposition systems in the early stage of rift evolution. Oblique crossing-faults, minor faults that develop on the erosional uplift in the interior foot-wall, would cut the uplifts and provide faulted-through paths for the over-filled sediments in the accommodation space, making it possible to develop sedimentary systems towards the center of basin during the early stage of rift evolution, although the origins of such minor faults still need further discussion. The results of this research indicate that different types of fault interactions have a fundamental control on patterns of sediment dispersal during early stage of rift basins.

Sedimentary processes and depositional environments of the Horn River Shale in British Columbia, Canada

Science.gov (United States)

Yoon, Seok-Hoon; Koh, Chang-Seong; Joe, Young-Jin; Woo, Ju-Hwan; Lee, Hyun-Suk

2017-04-01

The Horn River Basin in the northeastern British Columbia, Canada, is one of the largest unconventional gas accumulations in North America. It consists mainly of Devonian shales (Horn River Formation) and is stratigraphically divided into three members, the Muskwa, Otterpark and Evie in descending order. This study focuses on sedimentary processes and depositional environments of the Horn River shale based on sedimentary facies analysis aided by well-log mineralogy (ECS) and total organic carbon (TOC) data. The shale formation consists dominantly of siliceous minerals (quartz, feldspar and mica) and subordinate clay mineral and carbonate materials, and TOC ranging from 1.0 to 7.6%. Based on sedimentary structures and micro texture, three sedimentary facies were classified: homogeneous mudstone (HM), indistinctly laminated mudstone (ILM), and planar laminated mudstone (PLM). Integrated interpretation of the sedimentary facies, lithology and TOC suggests that depositional environment of the Horn River shale was an anoxic quiescent basin plain and base-of-slope off carbonate platform or reef. In this deeper marine setting, organic-rich facies HM and ILM, dominant in the Muskwa (the upper part of the Horn River Formation) and Evie (the lower part of the Horn River Formation) members, may have been emplaced by pelagic to hemipelagic sedimentation on the anoxic sea floor with infrequent effects of low-density gravity flows (turbidity currents or nepheloid flows). In the other hand, facies PLM typifying the Otterpark Member (the middle part of the Horn River Formation) suggests more frequent inflow of bottom-hugging turbidity currents punctuating the hemipelagic settling of the background sedimentation process. The stratigraphic change of sedimentary facies and TOC content in the Horn River Formation is most appropriately interpreted to have been caused by the relative sea-level change, that is, lower TOC and frequent signal of turbidity current during the sea

Geothermal reservoir simulation of hot sedimentary aquifer system using FEFLOW®

Science.gov (United States)

Nur Hidayat, Hardi; Gala Permana, Maximillian

2017-12-01

The study presents the simulation of hot sedimentary aquifer for geothermal utilization. Hot sedimentary aquifer (HSA) is a conduction-dominated hydrothermal play type utilizing deep aquifer, which is heated by near normal heat flow. One of the examples of HSA is Bavarian Molasse Basin in South Germany. This system typically uses doublet wells: an injection and production well. The simulation was run for 3650 days of simulation time. The technical feasibility and performance are analysed in regards to the extracted energy from this concept. Several parameters are compared to determine the model performance. Parameters such as reservoir characteristics, temperature information and well information are defined. Several assumptions are also defined to simplify the simulation process. The main results of the simulation are heat period budget or total extracted heat energy, and heat rate budget or heat production rate. Qualitative approaches for sensitivity analysis are conducted by using five parameters in which assigned lower and higher value scenarios.

Archaeology. Sedimentary DNA from a submerged site reveals wheat in the British Isles 8000 years ago.

Science.gov (United States)

Smith, Oliver; Momber, Garry; Bates, Richard; Garwood, Paul; Fitch, Simon; Pallen, Mark; Gaffney, Vincent; Allaby, Robin G

2015-02-27

The Mesolithic-to-Neolithic transition marked the time when a hunter-gatherer economy gave way to agriculture, coinciding with rising sea levels. Bouldnor Cliff, is a submarine archaeological site off the Isle of Wight in the United Kingdom that has a well-preserved Mesolithic paleosol dated to 8000 years before the present. We analyzed a core obtained from sealed sediments, combining evidence from microgeomorphology and microfossils with sedimentary ancient DNA (sedaDNA) analyses to reconstruct floral and faunal changes during the occupation of this site, before it was submerged. In agreement with palynological analyses, the sedaDNA sequences suggest a mixed habitat of oak forest and herbaceous plants. However, they also provide evidence of wheat 2000 years earlier than mainland Britain and 400 years earlier than proximate European sites. These results suggest that sophisticated social networks linked the Neolithic front in southern Europe to the Mesolithic peoples of northern Europe. Copyright © 2015, American Association for the Advancement of Science.

Average sedimentary rock rare Earth element patterns and crustal evolution: Some observations and implications from the 3800 Ma ISUA supracrustal belt, West Greenland

Science.gov (United States)

Dymek, R. F.; Boak, J. L.; Gromet, L. P.

1983-01-01

Rare earth element (REE) data is given on a set of clastic metasediments from the 3800 Ma Isua Supracrustal belt, West Greenland. Each of two units from the same sedimentary sequence has a distinctive REE pattern, but the average of these rocks bears a very strong resemblance to the REE pattern for the North American Shale Composite (NASC), and departs considerably from previous estimates of REE patterns in Archaean sediments. The possibility that the source area for the Isua sediments resembled that of the NASC is regarded as highly unlikely. However, REE patterns like that in the NASC may be produced by sedimentary recycling of material yielding patterns such as are found at Isua. The results lead to the following tentative conclusions: (1) The REE patterns for Isua Seq. B MBG indicate the existence of crustal materials with fractionated REE and negative Eu anomalies at 3800 Ma, (2) The average Seq. B REE pattern resembles that of the North American Shale Composite (NASC), (3) If the Seq. B average is truly representative of its crustal sources, then this early crust could have been extensively differentiated. In this regard, a proper understanding of the NASC pattern, and its relationship to post-Archaean crustal REE reservoirs, is essential, (4) The Isua results may represent a local effect.

Finite-strain analysis of Metavolcano-sedimentary rocks at Gabel El Mayet area, Central Eastern Desert, Egypt

Science.gov (United States)

Kassem, Osama M. K.; Abd El Rahim, Said H.

2010-09-01

Finite strain was estimated in the metavolcano-sedimentary rocks, which surround by serpentinites of Gabel El Mayet area. Finite strain shows a relationship to nappe contacts between the metavolcano-sedimentary rocks and serpentinite and sheds light on the nature of the subhorizontal foliation typical for the Gable Mayet shear zone. We used the Rf/ ϕ and Fry methods on feldspar porphyroclasts and mafic grains from 10 metasedimentary and six metavolcanic samples in Gabel El Mayet region. Our finite-strain data show that the metavolcano-sedimentary rocks were moderately deformed and axial ratios in the XZ section range from 1.9 to 3.9. The long axes of the finite-strain ellipsoids trend W/WNW in the north and W/WSW in the south of the Gabel El Mayet shear zone. Furthermore, the short axes are subvertical to a subhorizontal foliation. The strain magnitudes increase towards the tectonic contacts between the metavolcano-sedimentary rocks and serpentinite. The data indicate oblate strain symmetry in the metavolcano-sedimentary rocks. Hence, our strain data also indicate flattening strain. We assume that the metasedimentary and metavolcanics rocks have similar deformation behaviour. The fact that finite strain accumulated during the metamorphism indicates that the nappe contacts formed during the accumulation of finite strain and thus during thrusting. We conclude that the nappe contacts formed during progressive thrusting under brittle to semi-brittle deformation conditions by simple shear and involved a component of vertical shortening, which caused the subhorizontal foliation in the Gabel El Mayet shear zone.

Potential Cement Phases in Sedimentary Rocks Drilled by Curiosity at Gale Crater, Mars

Science.gov (United States)

Rampe, E. B.; Morris, R. V.; Bish, D. L.; Chipera, S. J.; Ming, D. W.; Blake, D. F.; Vaniman, D. T.; Bristow, T. F.; Cavanagh, P.; Farmer, J. D.;

Ambient Temperature Flotation of Sedimentary Phosphate Ore Using Cottonseed Oil as a Collector

Directory of Open Access Journals (Sweden)

Yaoyang Ruan

2017-04-01

Full Text Available The mid-low grade sedimentary phosphate ore, abundant in silicate and carbonate gangue minerals, exhibits a poor processability. It is conventionally enriched using high temperature flotation to remove silicate gangues with fatty acid as a collector. Cottonseed oil has been proved to be an efficient collector for achieving ambient temperature flotation of the sedimentary phosphate ore used in this study. Flotation kinetics was investigated to ascertain the excellent collecting performance of cottonseed oil, as compared with oleic acid, and the phosphate flotation fitted well with the first-order flotation model. Based on the analysis of flotation reagent effect on the direct flotation process using the response surface methodology (RSM, a closed circuit of direct-reverse flotation for stepwise removing silicate and carbonate gangues from the sedimentary phosphate ore was established. Consequently, a required high quality of phosphate concentrate containing 30.16% P2O5 was obtained, with a recovery of 90.90%. Scanning electron microscopy (SEM and X-ray diffraction analysis (XRD of the flotation products confirmed that the majority of silicate and carbonate gangues were effectively removed from the concentrate products.

Epigenetic alteration of sedimentary rocks at hydrogenic uranium deposit

International Nuclear Information System (INIS)

Ding Wanlie; Shen Kefeng

2001-01-01

The author introduces the concept, the recognition criteria, the genesis and classification of the epigenetic alteration of sedimentary rocks in brief, and expounds the mineral-geochemical indications and characteristics of oxidation and reduction alterations in different geochemical zones in detail, and proposes the two models of ore-controlling zonation of epigenetic alteration. The authors finally introduce research methods of epigenetic alteration

Evolution of fore-arc and back-arc sedimentary basins with focus on the Japan subduction system and its analogues

Science.gov (United States)

Sato, Hiroshi; Ishiyama, Tatsuya; Matenco, Liviu; Nader, Fadi Henri

2017-07-01

The International Lithosphere Program (ILP) seeks to elucidate the nature, dynamics, origin and evolution of the lithosphere through international, multidisciplinary geoscience research projects and coordinating committees (Cloetingh and Negendank, 2010). The focus of the Task Force VI Sedimentary Basins activities is to foster collaborations between academia, research institutes and industry in all domains relevant for the understanding of sedimentary basins, from regional to nano-scale, from the deep earth to near surface processes (e.g., Roure et al., 2010, 2013). In this activity, it is important to develop and validate novel concepts of sedimentary basin evolution and topography building by incorporating geological/geophysical datasets and methodologies applied to worldwide natural laboratories (Cloetingh et al., 2011; Cloetingh and Willett, 2013; Matenco and Andriessen, 2013). The Task Force aims to understand and predict the processes that control the formation and evolution of the coupled orogens and sedimentary basins system through integration of field studies, analytical techniques and numerical/analogue modelling. At the same time, the Task Force aims to promote research in the domain of sedimentary basins evolution and quantitative tectonics for the study of mountain building and the subsequent extensional collapse, and their quantitative implications for vertical motions on different temporal and spatial scales (Gibson et al., 2015; Matenco et al., 2016; Roure, 2008; Seranne et al., 2015). The implications of tectonics on basin fluids (fluid-flow and rock-fluid interactions) are important to understand and predict geo-resources (e.g., Nader, 2016). Important is to initiate innovative research lines in linking the evolution of sedimentary systems by integrating cross-disciplinary expertise with a focus on integrated sedimentary basins and orogenic evolution. The key is to strengthen the synergy between academic research and applied industry in large

Stratigraphy and Facies Analysis of a 122 M Long Lacustrine Sequence from Chalco Lake, Central Mexico

Science.gov (United States)

Herrera, D. A.; Ortega, B.; Caballero, M.; Lozano, S.; Pi, T.; Brown, E. T.

2010-12-01

Chalco lake is located SE of the outskirts of Mexico City, at the central part of the Trans Mexican Volcanic Belt. Previous studies show the importance of this lacustrine sequence as an archive of paleoenvironmental and paleoclimatic changes. A set of five cores up to 122 m depth were drilled in the basin, in order to analyze the sedimentary record and to extent the previous knowledge of past environmental changes in central Mexico. As an initial step, in this work we present the identification and classification of sedimentary facies. Preliminary paleomagnetism analyses recognize the possible record of the Blake Event (ca. 120 kyr BP), and suggest that the sequence might span the last 240 kyr. In this case, variations in sedimentary facies could reflect the conditions of the MIS 1-7. The facies are mostly diatom ooze, carbonate mud, organic rich silt and volcaniclastic, both massive and laminated, and massive dark gray to reddish brown silt. From 1 to 8 m depth dominates the organic rich silt facies, which correlates with the MIS 1. Intercalations of reddish brown and grayish brown silt facies, between 8 to 60 m depth, indicate changes occurred during MIS 2 to 5d. Between 60-75 m depth the sequence is characterized by dark grayish silty clay facies, which possibly coincide with the MIS 5e. At 79 m depth (ca. 130 kyr BP) we found struvite (MgNH4PO4.6H2O), which may be related to dry conditions. The laminated diatom ooze facies dominates between 90 to 122 m depth and indicates rhythmic changes in the sediment deposition of the basin. The volcaniclastic facies is represented by lapilli and ash deposits in more than 100 individual tephra layers of both mafic and felsic composition. Some of them correspond to main volcanic eruptions, as the Upper Toluca Pumice (13,500 cal yr BP), from the Nevado de Toluca volcano and the Pómez con Andesita (17,700 cal yr BP) from the Popocatépetl volcano. The carbonate mud facies is composed of calcite and siderite, with frequent

Student learning and understanding of sequence stratigraphic principles

Science.gov (United States)

Herrera, Juan Sebastian

Research in geoscience education addressing students' conceptions of geological subjects has concentrated in topics such as geological time, plate tectonics, and problem solving in the field, mostly in K-12 and entry level college scenarios. Science education research addressing learning of sedimentary systems in advance undergraduates is rather limited. Therefore, this dissertation contributed to filling that research gap and explored students' narratives when explaining geological processes associated with the interaction between sediment deposition and sea level fluctuations. The purpose of the present study was to identify the common conceptions and alternative conceptions held by students when learning the basics of the sub discipline known as sequence stratigraphy - which concepts students were familiar and easily identified, and which ones they had more difficulty with. In addition, we mapped the cognitive models that underlie those conceptions by analyzing students' gestures and conceptual metaphors used in their explanations. This research also investigated the interaction between geoscientific visual displays and student gesturing in a specific learning context. In this research, an in-depth assessment of 27 students' ideas of the basic principles of sequence stratigraphy was completed. Participants were enrolled in advanced undergraduate stratigraphy courses at three research-intensive universities in Midwest U.S. Data collection methods included semi-structured interviews, spatial visualization tests, and lab assignments. Results indicated that students poorly integrated temporal and spatial scales in their sequence stratigraphic models, and that many alternative conceptions were more deeply rooted than others, especially those related to eustasy and base level. In order to better understand the depth of these conceptions, we aligned the analysis of gesture with the theory of conceptual metaphor to recognize the use of mental models known as image

The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam Onboard Curiosity

Science.gov (United States)

Le Deit, Laetitia; Mangold, Nicolas; Forni, Olivier; Cousin, Agnes; Lasue, Jeremie; Schröder, Susanne; Wiens, Roger C.; Sumner, Dawn Y.; Fabre, Cecile; Stack, Katherine M.; Anderson, Ryan; Blaney, Diana L.; Clegg, Samuel M.; Dromart, Gilles; Fisk, Martin; Gasnault, Olivier; Grotzinger, John P.; Gupta, Sanjeev; Lanza, Nina; Le Mouélic, Stephane; Maurice, Sylvestre; McLennan, Scott M.; Meslin, Pierre-Yves; Nachon, Marion; Newsom, Horton E.; Payre, Valerie; Rapin, William; Rice, Melissa; Sautter, Violaine; Treiman, Alan H.

2016-01-01

The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K2O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

Palynoflora from Deccan volcano-sedimentary sequence ...

Indian Academy of Sciences (India)

Prakash

2009-11-02

Nov 2, 2009 ... The eruption of Deccan volcanic flows severely affected the existing floral association and ... higher stratigraphic levels, abundance of fungi especially the .... dicot; Mohabey and Udhoji 1996), fruits of Capparidaceae.

Elemental geochemistry of sedimentary rocks at Yellowknife Bay, Gale crater, Mars

NARCIS (Netherlands)

McLennan, S.M.; Anderson, R.B.; Bell III, J.F.; Bridges, J.C.; Calef III, F.; Campbell, J.L.; Clark, B.C.; Clegg, S.; Conrad, P.; Cousin, A.; Des Marais, D.J.; Dromart, G.; Dyar, M.D.; Edgar, L.A.; Ehlmann, B.L.; Fabre, C.; Forni, O.; Gasnault, O.; Gellert, R.; Gordon, S.; Grant, J.A.; Grotzinger, J.P.; Gupta, S.; Herkenhoff, K.E.; Hurowitz, J.A.; King, P.L.; Mouélic, S.L.; Leshin, L.A.; Léveillé, R.; Lewis, K.W.; Mangold, N.; Maurice, S.; Ming, D.W.; Morris, R.V.; Nachon, M.; Newsom, H.E.; Ollila, A.M.; Perrett, G.M.; Rice, M.S.; Schmidt, M.E.; Schwenzer, S.P.; Stack, K.; Stolper, E.M.; Sumner, D.Y.; Treiman, A.H.; VanBommel, S.; Vaniman, D.T.; Vasavada, A.; Wiens, R.C.; Yingst, R.A.; ten Kate, Inge Loes|info:eu-repo/dai/nl/292012217

2014-01-01

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold,

Sedimentary dykes in the Oskarshamn-Vaestervik area. A study of the mechanism of formation

International Nuclear Information System (INIS)

Roeshoff, Kennert; Cosgrove, John

2002-07-01

This study of the sedimentary dykes from the Oskarshamn-Vaestervik area, near Aespoe and surrounding region, is aimed at understanding the mechanism of their formation. In particular it is important to establish whether or not they formed by the injection of high pressure fluidized sediments and if so what the likely effect of any future over pressured sediments will be on the stability of the fracture network in the basement rocks at Aespoe. This report is made up of a review of the literature on sedimentary dykes, a discussion of the various mechanical models for hydraulic fracturing and a description of the field and laboratory study carried out on the sedimentary dykes. The literature review indicates a remarkable consensus on the mode of formation of these structures based on their fabric (particularly layering generated in part by variation in clast size) and the composition of the infilling material. Two modes of origin have been recognised. These are the passive infilling of dykes where the dyke material has entered an open fracture under the influence of gravity, and active, i.e. forceful injection of a fluidized sediment under high pressure into a pre-existing fracture or into a fracture generated by the high pressure fluid. The discussion of the theory of fluid induced fracturing leads to the recognition of three systems which are the two end members and an intermediate form of a complete spectrum of materials ranging from unconsolidated and incohesive sediments, through cemented but porous rocks to crystalline rocks with no intrinsic porosity and whose only porosity relates to that imparted by the fracture network that the rock contains. The theory best suited to analyses this latter system is one based on fracture mechanics and is known as the theory of external hydraulic fracturing. From the point of view of the sedimentary dykes in the study area around the Aespoe Hard Rock Laboratory, where the dykes occur in the fractured granitic basement, this is

Sedimentary dykes in the Oskarshamn-Vaestervik area. A study of the mechanism of formation

Energy Technology Data Exchange (ETDEWEB)

Roeshoff, Kennert [BBK AB, Solna (Sweden); Cosgrove, John [Imperial College, London (United Kingdom). Dept. of Earth Sciences and Engineering

2002-07-01

This study of the sedimentary dykes from the Oskarshamn-Vaestervik area, near Aespoe and surrounding region, is aimed at understanding the mechanism of their formation. In particular it is important to establish whether or not they formed by the injection of high pressure fluidized sediments and if so what the likely effect of any future over pressured sediments will be on the stability of the fracture network in the basement rocks at Aespoe. This report is made up of a review of the literature on sedimentary dykes, a discussion of the various mechanical models for hydraulic fracturing and a description of the field and laboratory study carried out on the sedimentary dykes. The literature review indicates a remarkable consensus on the mode of formation of these structures based on their fabric (particularly layering generated in part by variation in clast size) and the composition of the infilling material. Two modes of origin have been recognised. These are the passive infilling of dykes where the dyke material has entered an open fracture under the influence of gravity, and active, i.e. forceful injection of a fluidized sediment under high pressure into a pre-existing fracture or into a fracture generated by the high pressure fluid. The discussion of the theory of fluid induced fracturing leads to the recognition of three systems which are the two end members and an intermediate form of a complete spectrum of materials ranging from unconsolidated and incohesive sediments, through cemented but porous rocks to crystalline rocks with no intrinsic porosity and whose only porosity relates to that imparted by the fracture network that the rock contains. The theory best suited to analyses this latter system is one based on fracture mechanics and is known as the theory of external hydraulic fracturing. From the point of view of the sedimentary dykes in the study area around the Aespoe Hard Rock Laboratory, where the dykes occur in the fractured granitic basement, this is

Analysis for preliminary evaluation of discrete fracture flow and large-scale permeability in sedimentary rocks

International Nuclear Information System (INIS)

Kanehiro, B.Y.; Lai, C.H.; Stow, S.H.

1987-05-01

Conceptual models for sedimentary rock settings that could be used in future evaluation and suitability studies are being examined through the DOE Repository Technology Program. One area of concern for the hydrologic aspects of these models is discrete fracture flow analysis as related to the estimation of the size of the representative elementary volume, evaluation of the appropriateness of continuum assumptions and estimation of the large-scale permeabilities of sedimentary rocks. A basis for preliminary analysis of flow in fracture systems of the types that might be expected to occur in low permeability sedimentary rocks is presented. The approach used involves numerical modeling of discrete fracture flow for the configuration of a large-scale hydrologic field test directed at estimation of the size of the representative elementary volume and large-scale permeability. Analysis of fracture data on the basis of this configuration is expected to provide a preliminary indication of the scale at which continuum assumptions can be made

X-ray diffraction analysis of clay stones, Muglad Sedimentary Basin, Sudan

International Nuclear Information System (INIS)

Ali, A. E.

1997-01-01

This study deals with the theoretical and experimental aspects of X-ray diffraction (XRD) technique. Moreover the XRD technique has been used to investigate the clay mineral types and their distribution for samples obtained from exploration wells in the Mugald Sedimentary Basin in Western Sudan. The studied samples range in depth from 1524 m to 4572 m. The XRD analysis of samples shows that they consist of kaolinite, smectite, illite, chlorite and the mixed-layer smectite/illite. Kaolinite has higher abundance (15 - 72 %) followed by illite (7 - 34 %), smectite (11 - 76 %) and the less abundance of chlorite and the mixed-layer smectite/illite. Non-clay minerals found include quartz and cristabolite. The clay mineral types and their vertical distribution reflect various controls such as environmental, burial diagenesis, source rocks and climatic influences in the Muglad Sedimentary Basin. (author). 19 refs., 11 figs., 3 tabs

3D coupled heat and mass transfer processes at the scale of sedimentary basisn

Science.gov (United States)

Cacace, M.; Scheck-Wenderoth, M.; Kaiser, B. O.

2014-12-01

We use coupled 3D simulations of fluid, heat, and transport based on a 3D structural model of a complex geological setting, the Northeast German Basin (NEGB). The geological structure of the NEGB is characterized by a relatively thick layer of Permian Zechstein salt, structured in differnet diapirs (up to 5000 m thick) and pillows locally reaching nearly the surface. Salt is thermally more conductive than other sediments, hydraulically impervious but highly solvable. Thus salt structures have first order influence on the temperature distribution, the deep flow regime and the salinity of groundawater bearing aquifers. In addition, the post-Permian sedimentary sequence is vertically subdivided into several aquifers and aquitards. The shallow Quaternary to late Tertiary freshwater aquifer is separated from the underlying Mesozoic saline aquifers by an embedded Tertiary clay enriched aquitard (Rupelian Aquitard). An important feature of this aquitard is that hydraulic connections between the upper and lower aquifers exist in areas where the Rupelian Aquitard is missing (hydrogeological windows). By means of 3D numerical simulations we explore the role of heat conduction, pressure, and density driven groundwater flow as well as fluid viscosity-related and salinity-dependent effects on the resulting flow and temperature fields. Our results suggest that the regional temperature distribution within the basin results from interactions between regional pressure forces and thermal diffusion locally enhanced by thermal conductivity contrasts between the different sedimentary rocks with the highly conductive salt. Buoyancy forces triggered by temperature-dependent fluid density variations affect only locally the internal thermal configuration. Locations, geometry, and wavelengths of convective thermal anomalies are mainly controlled by the permeability field and thickness values of the respective geological layers. Numerical results from 3D thermo-haline numerical simulations

Permanganate diffusion and reaction in sedimentary rocks.

Science.gov (United States)

Huang, Qiuyuan; Dong, Hailiang; Towne, Rachael M; Fischer, Timothy B; Schaefer, Charles E

2014-04-01

In situ chemical oxidation using permanganate has frequently been used to treat chlorinated solvents in fractured bedrock aquifers. However, in systems where matrix back-diffusion is an important process, the ability of the oxidant to migrate and treat target contaminants within the rock matrix will likely determine the overall effectiveness of this remedial approach. In this study, a series of diffusion experiments were performed to measure the permanganate diffusion and reaction in four different types of sedimentary rocks (dark gray mudstone, light gray mudstone, red sandstone, and tan sandstone). Results showed that, within the experimental time frame (~2 months), oxidant migration into the rock was limited to distances less than 500 μm. The observed diffusivities for permanganate into the rock matrices ranged from 5.3 × 10(-13) to 1.3 × 10(-11) cm(2)/s. These values were reasonably predicted by accounting for both the rock oxidant demand and the effective diffusivity of the rock. Various Mn minerals formed as surface coatings from reduction of permanganate coupled with oxidation of total organic carbon (TOC), and the nature of the formed Mn minerals was dependent upon the rock type. Post-treatment tracer testing showed that these Mn mineral coatings had a negligible impact on diffusion through the rock. Overall, our results showed that the extent of permanganate diffusion and reaction depended on rock properties, including porosity, mineralogy, and organic carbon. These results have important implications for our understanding of long-term organic contaminant remediation in sedimentary rocks using permanganate. Copyright © 2014 Elsevier B.V. All rights reserved.

Realistic modelling of observed seismic motion in complex sedimentary basins

International Nuclear Information System (INIS)

Faeh, D.; Panza, G.F.

1994-03-01

Three applications of a numerical technique are illustrated to model realistically the seismic ground motion for complex two-dimensional structures. First we consider a sedimentary basin in the Friuli region, and we model strong motion records from an aftershock of the 1976 earthquake. Then we simulate the ground motion caused in Rome by the 1915, Fucino (Italy) earthquake, and we compare our modelling with the damage distribution observed in the town. Finally we deal with the interpretation of ground motion recorded in Mexico City, as a consequence of earthquakes in the Mexican subduction zone. The synthetic signals explain the major characteristics (relative amplitudes, spectral amplification, frequency content) of the considered seismograms, and the space distribution of the available macroseismic data. For the sedimentary basin in the Friuli area, parametric studies demonstrate the relevant sensitivity of the computed ground motion to small changes in the subsurface topography of the sedimentary basin, and in the velocity and quality factor of the sediments. The total energy of ground motion, determined from our numerical simulation in Rome, is in very good agreement with the distribution of damage observed during the Fucino earthquake. For epicentral distances in the range 50km-100km, the source location and not only the local soil conditions control the local effects. For Mexico City, the observed ground motion can be explained as resonance effects and as excitation of local surface waves, and the theoretical and the observed maximum spectral amplifications are very similar. In general, our numerical simulations permit the estimate of the maximum and average spectral amplification for specific sites, i.e. are a very powerful tool for accurate micro-zonation. (author). 38 refs, 19 figs, 1 tab

High-resolution sequence stratigraphy and its controls on uranium mineralization. Taking middle Jurassic Qingtujing formation in Chaoshui basin as an example

International Nuclear Information System (INIS)

Yao Chunling; Guo Qingyin; Chen Zuyi; Liu Hongxu

2006-01-01

By applying the high-resolution sequence stratigraphy, the different sub-divisions of base-level cycles of Qingtujing Formation, Middle Jurassic in Chaoshui Basin are analyzed in detail. 23 short, 3 middle and 1 long base-level cycles are recognized. On the above basis, the corresponding frameworks of high-resolution sequence stratigraphy have been established in northern and southern sub-basins respectively, and the detailed sedimentary facies of MSC 1-3 and the special distribution of Qintujing Formation are discussed. It is pointed out that MSC 2 is the most favorable layer for the localization of sandstone-type uranium deposits. (authors)

To what extent can intracrater layered deposits that lack clear sedimentary textures be used to infer depositional environments?

Science.gov (United States)

Cadieux, Sarah B.; Kah, Linda C.

2015-03-01

Craters within Arabia Terra, Mars, contain hundreds of meters of layered strata showing systematic alternation between slope- and cliff-forming units, suggesting either rhythmic deposition of distinct lithologies or similar lithologies that experienced differential cementation. On Earth, rhythmically deposited strata can be examined in terms of stratal packaging, wherein the interplay of tectonics, sediment deposition, and base level (i.e., the position above which sediment accumulation is expected to be temporary) result in changes in the amount of space available for sediment accumulation. These predictable patterns of sediment deposition can be used to infer changes in basin accommodation regardless of the mechanism of deposition (e.g. fluvial, lacustrine, or aeolian). Here, we analyze sedimentary deposits from three craters (Becquerel Crater, Danielson Crater, Crater A) in Arabia Terra. Each crater contains layered deposits that are clearly observed in orbital images. Although orbital images are insufficient to specifically determine the origin of sedimentary deposits, depositional couplets can be interpreted in terms of potential accommodation space available for deposition, and changes in the distribution of couplet thickness through stratigraphy can be interpreted in terms of changing base level and the production of new accommodation space. Differences in stratal packaging in these three craters suggest varying relationships between sedimentary influx, sedimentary base level, and concomitant changes in accommodation space. Previous groundwater upwelling models hypothesize that layered sedimentary deposits were deposited under warm climate conditions of early Mars. Here, we use observed stacking patterns to propose a model for deposition under cold climate conditions, wherein episodic melting of ground ice could raise local base level, stabilize sediment deposition, and result in differential cementation of accumulated strata. Such analysis demonstrates that

Petroleum source-rock potentials of the cretaceous transgressive-regressive sedimentary sequences of the Cauvery Basin

Science.gov (United States)

Chandra, Kuldeep; Philip, P. C.; Sridharan, P.; Chopra, V. S.; Rao, Brahmaji; Saha, P. K.

The present work is an attempt to contribute to knowledge on the petroleum source-rock potentials of the marine claystones and shales of basins associated with passive continental margins where the source-rock developments are known to have been associated with the anoxic events in the Mesozoic era. Data on three key exploratory wells from three major depressions Ariyallur-Pondicherry, Thanjavur and Nagapattinam of the Cauvery Basin are described and discussed. The average total organic carbon contents of the transgressive Pre-Albian-Cinomanian and Coniacian/Santonian claystones/shales range from 1.44 and 1.16%, respectively. The transgressive/regressive Campanian/Maastrichtian claystones contain average total organic carbon varying from 0.62 to 1.19%. The kerogens in all the studied stratigraphic sequences are classified as type-III with Rock-Eval hydrogen indices varying from 30 to 275. The nearness of land masses to the depositional basin and the mainly clastic sedimentation resulted in accumulation and preservation of dominantly type-III kerogens. The Pre-Albian to Cinomanian sequences of peak transgressive zone deposited in deep marine environments have kerogens with a relatively greater proportion of type-II components with likely greater contribution of planktonic organic matters. The global anoxic event associated with the Albian-Cinomanian marine transgression, like in many other parts of the world, has pervaded the Cauvery Basin and favoured development of good source-rocks with type-III kerogens. The Coniacian-Campanian-Maastrichtian transgressive/regressive phase is identified to be relatively of lesser significance for development of good quality source-rocks.

The Cenozoic western Svalbard margin: sediment geometry and sedimentary processes in an area of ultraslow oceanic spreading

OpenAIRE

Amundsen, Ingrid Marie Hasle; Blinova, Maria; Hjelstuen, Berit Oline; Mjelde, Rolf; Haflidason, Haflidi

2011-01-01

The northeastern high-latitude North Atlantic is characterised by the Bellsund and Isfjorden fans on the continental slope off west Svalbard, the asymmetrical ultraslow Knipovich spreading ridge and a 1,000 m deep rift valley. Recently collected multichannel seismic profiles and bathymetric records now provide a more complete picture of sedimentary processes and depositional environments within this region. Both downslope and alongslope sedimentary processes are identi...

Magmatism in the brazilian sedimentary basins and the petroleum geology; Magmatismo nas bacias sedimentares brasileiras e sua influencia na geologia do petroleo

Energy Technology Data Exchange (ETDEWEB)

Thomaz Filho, Antonio; Antonioli, Luzia [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Faculdade de Geologia]. E-mails: antoniothomaz@globo.com; antonioli@novanet.com.br; Mizusaki, Ana Maria Pimentel [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Geociencias]. E-mail: ana.mizusaki@ufrgs.br

2008-06-15

In the recent years, the researches on the magmatic events that occurred in the Brazilian sedimentary basins had shown the importance of these episodes for the hydrocarbons exploration. The generation (heating), migration (structural and petrographic alterations), accumulation (basalt fractures) and migrations barriers (sills and dykes) of the hydrocarbons, produced for these rocks, are cited in the marginal and intra continental Brazilian basins. The magmatism produce the temperature increase in the sedimentary basin, around its intrusion, and this propitiate the maturation of the organic matter contained in the hydrocarbons generating rocks of the basin. At the same time, has been verified that the contacts dykes/sedimentary rocks can represent important ways for the hydrocarbons migrations. Recent studies have shown that the magmatism, in its extrusive manifestations, can be analyzed in view of the possibility of having acted as effective hydrocarbon seals and, in consequence, making possible the accumulation of hydrocarbons generated in the underlying sediments. The magmatism of predominantly basic to intermediary character is generated in the asthenosphere, that is, below the lithosphere. The dykes that had introduced in the basement of our sedimentary basins are good heat conductors and we can expect the geothermal gradients increase in the overlapped sedimentary deposits. The more detailed study of the magmatic processes in the Brazilian sedimentary basins must lead to new forms of hydrocarbons exploration in our sedimentary basins, also in those basins where the traditional exploration activities have not occasioned the waited expected successes. (author)

Estimation of sedimentary proxy records together with associated uncertainty

OpenAIRE

Goswami, B.; Heitzig, J.; Rehfeld, K.; Marwan, N.; Anoop, A.; Prasad, S.; Kurths, J.

2014-01-01

Sedimentary proxy records constitute a significant portion of the recorded evidence that allows us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record intercomparisons. While there are various age-modeling approaches to improve the estimation of the age–depth relations of archives, relatively little focus has been placed on the propagation...

Hydrodynamic Controls on Muddy Sedimentary Fabric Development on Low-Gradient Shelves: Atchafalaya Chenier Plain Subaqueous Delta

Science.gov (United States)

Denommee, K.; Bentley, S. J.; Harazim, D.; Macquaker, J.

2016-02-01

Short sediment cores and geophysical data collected on the Southwest Louisiana Chenier Plain inner shelf have been studied in order to examine the sedimentary products of current-wave-enhanced sediment gravity flows (CWESGFs), a type of sediment gravity flow where the driving energy required to transport sediment across low-gradient settings is augmented by the near-bed orbital velocity of surface gravity wave and near-bed currents. Sedimentary fabrics observed on the SWLA shelf document the following flow evolution: (1) the erosion of the underlying substrate in response to wave-generated shear stresses in the bottom boundary layer, followed by (2) the deposition of ripple a crossbeded unit during wave-mediated oscillatory motions in low-viscosity suspension; (3) the deposition of subtle intercalated laminae during laminar flow at higher suspended sediment concentrations; followed by the deposition of (4) normally graded sediments during the waning phases of the flow. Significantly, the sedimentary fabrics deposited by CWESGFs on SWLA shelf show diagnostic variations from CWESGF-generated sedimentary fabrics observed on the Eel and Amazon shelves. Differences between the observed sedimentary fabrics are hypothesized to result from variations in the relative contribution of near-bed currents, wave orbital velocities, and bed slope (gravity) to the driving energy of the CWESGF, and as such can be catalogued as diagnostic recognition criteria using a prismatic ternary diagram where current-, wave-, and gravity-dominated end members form the vertices of a triangle, and wave period forms the prism axis. In this framework forcing mechanisms can be represented quantitatively, based on wave period and the relative contribution of each of the CWESGF velocity terms. This framework can be used to explore relationships between hydrodynamics and CWESGF fabrics, providing geologists with a tool with which to better recognize the depositional products of CWESGFs in the rock

Underground Research Laboratories for Crystalline Rock and Sedimentary Rock in Japan

Energy Technology Data Exchange (ETDEWEB)

Shigeta, N.; Takeda, S.; Matsui, H.; Yamasaki, S.

2003-02-27

The Japan Nuclear Cycle Development Institute (JNC) has started two off-site (generic) underground research laboratory (URL) projects, one for crystalline rock as a fractured media and the other for sedimentary rock as a porous media. This paper introduces an overview and current status of these projects.

The Stratigraphy and Lithofacies of the Paleoproterozoic Volcaniclastic Sequences in the Cape Three Points Area- Akodda section of the Southern in Ashanti Belt in the Birimian of southwest Ghana

Science.gov (United States)

Yoshimaru, S.; Kiyokawa, S.; Ito, T.; Ikehara, M.; Nyame, F. K.; Tetteh, G. M.

2015-12-01

The Paleoproterozoic Era is thought to have experienced one of the most significant changes in earth's environment during earth history. Early continents started to diverge and collide accompanied by first major oxidation of the atmosphere-oceanic system known as the Great Oxidation Environment (GOE). Due to their well-preserved oceanic sedimentary sequences, Paleoproterozoic belts are usually good targets for studies on the history of earth's past environment. In addition, these belts provide great help to understand the nature of the Paleoproterozoic deeper oceanic environments. Birimian greenstone belt in southwestern Ghana is likely to have made up of subduction of oceanic basin to form a volcanic island arc. Birimian rocks are separated by nonconformity from the Tarkwaian Group which is a younger paleoplacer deposit (Perrouty et al., 2012). The Birimian is made up of island-arc volcanic rocks; foreland basin made up of shale, sandstone, quartzite and turbidities derived from 2.17 Ga granite intrusions during Birimian volcanism. In this study, we focused on the coastal area around Cape Three Points at the southernmost part of the Ashanti (Axim-Konongo) belt in Ghana. In the eastern part of the area, excellently preserved Paleoprotorozoic deeper oceanic sedimentary sequences extensively outcrop for over 4km stretch. This volcano-sedimentary sequence has been affected by greenschist facies metamorphism. Structurally, this region preserves S1 cleavage and asymmetrical synform with west vergence and S0 younging to the east. Provisional stratigraphy is very continuous up to more than 2000m thick and, in addition, suggests at least four different fining upward sequences in the area to the east and west of Atwepo, west of Kwetakora and Akodda. These sub-sequences are mainly composed of volcaniclasitc, sandstone, black shale and rare volcanics such as pillow basalt or massive volcanic lava. In other words, this continuous sequence suggests distal submarine

Urban-touristic impacts on the aeolian sedimentary systems of the Canary Islands: conflict between development and conservation

OpenAIRE

Leví García-Romero; Antonio I. Hernández-Cordero; Elisabeth Fernández-Cabrera; Carolina Peña-Alonso; Luis Hernández-Calvento; Emma Pérez-Chacón

2016-01-01

Aeolian sedimentary systems in the Canary Islands differ significantly from other European and African systems due to their natural characteristics (climate, vegetation and insular isolation). Consequently, their geomorphological processes are unique. In turn, they are areas under high human pressure from touristic development. The aim of this paper is to analyze the impacts of urban-touristic development in four aeolian sedimentary systems in the Canaries: Maspalomas, Corralejo, Lambra and J...

Mining of sedimentary-type ore deposits

International Nuclear Information System (INIS)

Bruha, J.; Slovacek, T.; Berka, J.; Sadilek, P.

1992-01-01

A procedure is proposed for mining sedimentary-type ore deposits, particularly uranium deposits, using the stope-pillar technique. The stope having been mined out, the free room is filled with hydro-setting gob from the surface. A precondition for the application of this technique is horizontal ore mineralization in sediments where the total thickness of the mineralized ore layer is at least 3 to 5 m. Mining losses do not exceed 5%. For thicknesses greater than 5 m, the roof is reinforced and the walls are secured with netting. The assets of the technique include higher labor productivity of the driving, lower material demands in reinforcing and filling, lower power consumption, and reduced use of explosives. (Z.S.). 3 figs

The relationship between depositional system and ore-formation of sandstone-type uranium deposits in Dongsheng area, Ordos basin

International Nuclear Information System (INIS)

Zhao Honggang; Ou Guangxi

2006-01-01

The analysis on depositional system plays a very important role in studying sandstone-type uranium deposits. Based on depositional system analysis and sequence stratigraphy, and through the study of depositional system characteristics and the spatial distribution of sedimentary facies, the evolution of sedimentary environments as well as the sequence stratigraphy of Zhiluo Formation in Dongsheng area, Ordos basin, authors have come to the following conclusions, (1) the spatial distribution of sand bodies is controlled by the planar distribution of sedimentary facies, which, in turn, affects the spatial distribution of ore-hosting sand bodies; (2) the evolution of sedimentary facies and sedimentary environments creates good lithofacies and lithological conditions favorable for interlayer oxidation; (3) the spatial lithologic combination of 'three layer structure' is controlled by sedimentary sequence. (authors)

Characteristics of depositional environment and evolution of Upper Cretaceous Mishrif Formation, Halfaya Oil field, Iraq based on sedimentary microfacies analysis

Science.gov (United States)

Zhong, Yuan; Zhou, Lu; Tan, Xiucheng; Guo, Rui; Zhao, Limin; Li, Fei; Jin, Zhimin; Chen, Yantao

2018-04-01

As one of the most important carbonate targets in the Middle East, Upper Cretaceous Mishrif Formation has been highlighted for a long time. Although consensus has been reached on the overall sedimentary background, disputes still exist in understanding the sedimentary environment changes among sub-regions due to relatively limited research, rare outcrop, and incomplete drilled core, which hinders the analysis on sedimentary environment and thus the horizontal and vertical correlation. In this study, taking the Halfaya Oil Field as an example, the sedimentary microfacies analysis method was introduced to comprehensively characterize the cored interval of Mishrif Formation, including Single Layers MC1-1 to MA2. A total of 11 sedimentary microfacies are identified through system identification of sedimentary microfacies and environmental analysis, with reference to the standard microfacies classification in the rimmed carbonate platform. Then three kinds of environments are identified through microfacies assemblage analysis, namely restricted platform, open platform, and platform margin. Systematic analyses indicate that the deposits are mainly developed in the open platform and platform margin. Meanwhile, rock-electricity interpretation model is established according to the electricity response to cored intervals, and is then employed to interpret the uncored intervals, which finally helps build the sedimentary evolution pattern through horizontal and vertical correlation. It is proposed that the Single Layers MC1-1 to MB2-3 were deposited in the open platform featured by low water level, including sub-environments of low-energy shoal within platform and inter-shoal sea; Single Layers MB2-2 to MB1-2B were deposited in the open platform and platform margin, including sub-environments of high-energy shoal on the platform margin, low-energy shoal within platform, inter-shoal sea, and open sea; and Single Layers MB1-2A to MA2 were again deposited in the open platform

Rare earth elements and neodymium isotopes in sedimentary organic matter

Science.gov (United States)

Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

2014-09-01

We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter

Effects of Hypoxia on Sedimentary Nitrogen Cycling in the Pensacola Bay Estuary

Science.gov (United States)

Eutrophic-induced hypoxic events pose a serious threat to estuaries in coastal systems. Hypoxic events are becoming more intense and widespread with changes in land use and increased anthropogenic pressures. Microbial communities involved in sedimentary nitrogen (N) cycling may h...

The impact of sedimentary alkalinity release on the water column CO

NARCIS (Netherlands)

Brenner, H.; Braeckman, U.; Le Guitton, M.; Meysman, F.J.R.

2016-01-01

It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO₂ of seawater and hence increasing the CO₂ uptake from the atmosphere. To test this hypothesis, sedimentary

Geochemistry of shale and sedimentary pyrite as a proxy for gold fertility in the Selwyn basin area, Yukon

Science.gov (United States)

Sack, Patrick J.; Large, Ross R.; Gregory, Daniel D.

2018-01-01

Selwyn basin area strata contain sedimentary pyrite with Au above background levels when analyzed by laser ablation-inductively coupled mass spectrometry. Hyland Group rocks contain framboidal pyrite contents of 670 ppb Au, 1223 ppm As, and 5.3 ppm Te; the mean of all types of sedimentary pyrite in the Hyland Group is 391 ppb Au, 1489 ppm As, and 3.8 ppm Te. These levels are similar to sedimentary pyrite in host lithologies from major orogenic gold districts in New Zealand and Australia. Comparison of whole rock and pyrite data show that rocks deposited in continental slope settings with significant terrigenous input contain pyrite that is consistently enriched in Au, As, Te, Co, and Cu. Although data are limited, whole rock samples of stratigraphic units containing Au-rich pyrite also contain high Au, indicating that most of the Au is within sedimentary pyrite. Based on geologic characteristics and comparison of pyrite chemistry data with whole rock chemistry, Selwyn basin area strata have the necessary ingredients to form orogenic gold deposits: Au-enriched source rocks, metamorphic conditions permissive of forming a metamorphic ore fluid, and abundant structural preparation for channeling fluids and depositing ore.

Paleocene to Middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: biostratigraphy, allostratigraphy, and sequence stratigraphy

Science.gov (United States)

Poag, C.W.; Commeau, J.A.

1995-01-01

The Paleocene to Middle Miocene sedimentary fill of the southwestern Salisbury Embayment contains a fragmental depositional record, interrupted by numerous local diastems and regional unconformities. Using planktic foraminiferal biostratigraphy, 15 unconformity-bounded depositional units have been identified, assigned to six formations and seven alloformations previously recognized in the embayment. The units correlate with second- and third-order sequences of the Exxon sequence stratigraphy model, and include transgressive and highstand systems tracts. Alloformation, formation, and sequence boundaries are marked by abrupt, scoured, burrowed, erosional surfaces, which display lag deposits, biostratigraphic gaps, and intense reworking of microfossils above and below the boundaries.Paleocene deposits represent the upper parts of upper Pleocene Biochronozones P4 and P5, and rest uncomformably  on Cretaceous sedimentary beds of various ages (Maastrichtian to Albian). Lower Eocene deposits represent parts of Biochronozones P6 and P9. Middle Eocene strata represent mainly parts of Biochronozones P11, P12, and P14. Upper Eocene sediments include parts of Biochronozones P15, P16, and P17. Oligocene deposits encompass parts of Biochronozones. N4b to N7 undifferentiated, P21a, and, perhaps, N4a. Lower Miocene deposits encompass parts of Biochronozones N4b to N7 undifferentiated. Middle Miocene strata represent mainly parts of Biochronorones N8, N9, and N10.Nine plates of scanning electron micrographs illustrate the principal planktic foraminifera used to establish the biostratigraphic framework. Two new informal formine of Praeterenuitella praegemma Li, 1987, are introduced.

Magnetic properties of different grain-sized particles of sediments from the Okinawa Trough and their relationships to sedimentary environment

Institute of Scientific and Technical Information of China (English)

LI Ping; LI Peiying; ZHANG Xiaolong; CAO Chengxiao; XU Xingyong; DU Jun; LIU Lejun

2005-01-01

Multiple magnetic parameters were measured for nine different grain-sized fractions separated from the sediment samples that are representatives of four different sedimentary environments of the Okinawa Trough. Based on the measured results, the contributions of different grain-sized particles to total magnetic susceptibility of bulk sediments, the magnetic mineral assemblage and magnetic domain state as well as their relationships to sedimentary environment were discussed. Our research shows that the magnetic mineral is dominated by magnetite with a small amount of hematite and is primarily in pseudo-single-domain state. That indicates that the different sedimentary environments in the Okinawa Trough have certain correlation in material provenance. The magnetic minerals enrich in different grain-sized particles in response to different sedimentary environments. The contribution of the grain sizes from coarse to fine to coarse and fine to the magnetic susceptibility from the west to the east is in accordance with terrigenous material transportation from continental shelf of the East China Sea to the Okinawa Trough. It also shows difference in magnetic properties as a result of some environmental factors.

Petrological-geochemical characteristics of coarse-grained clastic sedimentary rocks of Quantou Formation, Cretaceous in Songliao basin and their geological significance

International Nuclear Information System (INIS)

Wang Gan; Zhang Bangtong

2005-01-01

Clastic sedimentary rocks of Quantou Formation, Cretaceous in Qing-an area, Songliao basin are mainly composed of sandstone, mudstone and siltstone. The petrological-chemical analysis of clastic sedimentary rocks from Quantou Formation, Cretaceous indicates that their lithology mainly consists of arkose, shale and minor rock debris sandstone and greywacke by chemical classification of bulk elements. REE distribution pattern displays the apparent enrichment of LREE and negative anomaly of Eu and is similar to that of NASC and PAAS. The ratio of trace-element in sedimentary rocks to that of upper crust shows gentle character. All the above features indicate that these sedimentary rocks were slowly deposited under weakly active tectonic setting. They are sediments typical for passive continental margin and active continental margin. It is suggested that material source of clastic sediments of Quantou Formation, Cretaceous in Qing-an area, Songliao basin was originated from Hercynian granite of Zhangguangchai Mountain, and the granite was originated from upper crust. (authors)

Description and hydrogeologic implications of cored sedimentary material from the 1975 drilling program at the Radioactive Waste Management Complex, Idaho

International Nuclear Information System (INIS)

Rightmire, C.T.

1984-08-01

Samples of sedimentary material from interbeds between basalt flows and from fractures in the flows, taken from two drill cores at the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory were analyzed for (1) particle-size distribution, (2) bulk mineralogy, (3) clay mineralogy, (4) cation-exchange capacity, and (5) carbonate content. Thin sections of selected sedimentary material were made for petrographic examination. These analyses are needed for a characterization of paths and rates of movement of radionuclides transported by infiltrating water. Preliminary interpretations indicate that (1) it may be possible to distinguish the various sedimentary interbeds on the basis of their mineralogy, (2) the presence of carbonate horizons in sedimentary interbeds may be utilized to approximate the time of exposure and the climate while the surface was exposed, and (3) the type and orientation of fracture-filling material may be utilized to determine the mechanism by which fractures were filled. 9 references, 14 figures, 8 tables

Questioning the Sedimentary Paradigm for Granites

Science.gov (United States)

Glazner, A. F.; Bartley, J. M.; Coleman, D. S.; Boudreau, A.; Walker, J. D.

2007-12-01

A critical question regarding volcano-pluton links is whether plutons are samples of magma that passed through on its way to eruption, or residues left behind after volcanic rocks were extracted. A persistent theme of recent work on granites sensu lato is that many are sedimentary accumulations of crystals that lost significant volumes of magmatic liquid. This view is based on observations of structures that clearly seem to reflect deposition on a magma chamber floor (e.g., flows of chilled mafic magma into silicic magma) and on the inference that many other structures, such as modal layering, truncated layering, and crystal accumulations, reflect crystal sedimentation on such chamber floors. There are significant physical and geochemical reasons to question this view, based on observations in the Sierra Nevada of California and similar results from other batholiths. First, few granites show the enrichments in Ba, Sr, and relative Eu that feldspar accumulation should produce. Second, sedimentary features such as graded bedding and cross-bedding form in highly turbulent flows, but turbulence is unachievable in viscous silicic liquids, where velocities on the order of 104 m/s would be required to induce turbulence in a liquid with η=104 Pa s. Third, tabular modally layered domains commonly cut surrounding modal layering on both sides, and orientations of modal layering and of the troughs of "ladder dikes" commonly scatter widely within hectare-sized areas; it is difficult to reconcile these features with gravity-driven settling. Fourth, accumulations of K-feldspar megacrysts are typically inferred to be depositional, but this is precluded by crystallization of most K- feldspar after rheologic lock-up occurs. Finally, accumulations of K-feldspar and hornblende are typically packed too tightly to be depositional. With analogy to layered mafic intrusions, many features attributed to crystal sedimentation in granites may be better explained by crystal aging and other in

Deformation style of the Mesozoic sedimentary rocks in southern Thailand

Science.gov (United States)

Kanjanapayont, Pitsanupong

2014-10-01

Mesozoic sedimentary rocks in southern Thailand are widespread from NNE-SSW and N-S in Chumphon and Trang provinces. The Mesozoic stratigraphic units are the marine Triassic Sai Bon Formation and the non-marine Jurassic-Cretaceous Thung Yai Group, the latter subdivided into Khlong Min, Lam Thap, Sam Chom, and Phun Phin Formations. These units overlie Permian carbonate rocks with an angular unconformity, and are overlain unconformably by Cenozoic units and the Quaternary sediments. The Mesozoic rocks have been folded to form two huge first-ordered syncline or synclinoria, the Chumphon and Surat Thani-Krabi-Trang synclinoria. These synclinoria are elongated in NNE-SSW to N-S direction, and incorporate asymmetric lower-order parasitic folds. The folds have moderately to steeply dipping eastward limbs and more gently dipping westward limbs. These folds were transected by brittle fractures in four major directions. These geologic structures indicate WNW-ESE to E-W contraction with top-to-the-east simple shear at some time before the deposition of the Cenozoic sedimentary units. No major deformation has affected the rocks subsequently, apart from the formation of the fault-controlled Cenozoic basins.

Constraining Depositional Slope From Sedimentary Structures in Sandy Braided Streams

Science.gov (United States)

Lynds, R. M.; Mohrig, D.; Heller, P. L.

2003-12-01

Determination of paleoslopes in ancient fluvial systems has potentially broad application to quantitatively constraining the history of tectonics and paleoclimate in continental sequences. Our method for calculating paleoslopes for sandy braided streams is based upon a simple physical model that establishes depositional skin-frictional shear stresses from assemblages of sedimentary structures and their associated grain size distributions. The addition of a skin-frictional shear stress, with a geometrically determined form-drag shear stress results in a total boundary shear stress which is directly related to water-surface slope averaged over an appropriate spatial scale. In order to apply this model to ancient fluvial systems, it is necessary to measure the following: coarsest suspended sediment size, finest grain size carried in bed load, flow depth, dune height, and dune length. In the rock record, suspended load and bed load can be accurately assessed by well-preserved suspended load deposits ("low-energy" ripples) and bed load deposits (dune foresets). This model predicts an average slope for the North Loup River near Taylor, Nebraska (modern case study) of 2.7 x 10-3. The measured reach-averaged water surface slope for the same reach of the river is 1.37 x 10-3. We suggest that it is possible to calculate the depositional slope of a sandy fluvial system by a factor of approximately two. Additionally, preliminary application of this model to the Lower Jurassic Kayenta Formation throughout the Colorado Plateau provides a promising and consistent evaluation of paleoslope in an ancient and well-preserved, sandy braided stream deposit.

Textural Maturity Analysis and Sedimentary Environment Discrimination Based on Grain Shape Data

Science.gov (United States)

Tunwal, M.; Mulchrone, K. F.; Meere, P. A.

2017-12-01

Morphological analysis of clastic sedimentary grains is an important source of information regarding the processes involved in their formation, transportation and deposition. However, a standardised approach for quantitative grain shape analysis is generally lacking. In this contribution we report on a study where fully automated image analysis techniques were applied to loose sediment samples collected from glacial, aeolian, beach and fluvial environments. A range of shape parameters are evaluated for their usefulness in textural characterisation of populations of grains. The utility of grain shape data in ranking textural maturity of samples within a given sedimentary environment is evaluated. Furthermore, discrimination of sedimentary environment on the basis of grain shape information is explored. The data gathered demonstrates a clear progression in textural maturity in terms of roundness, angularity, irregularity, fractal dimension, convexity, solidity and rectangularity. Textural maturity can be readily categorised using automated grain shape parameter analysis. However, absolute discrimination between different depositional environments on the basis of shape parameters alone is less certain. For example, the aeolian environment is quite distinct whereas fluvial, glacial and beach samples are inherently variable and tend to overlap each other in terms of textural maturity. This is most likely due to a collection of similar processes and sources operating within these environments. This study strongly demonstrates the merit of quantitative population-based shape parameter analysis of texture and indicates that it can play a key role in characterising both loose and consolidated sediments. This project is funded by the Irish Petroleum Infrastructure Programme (www.pip.ie)

The Triassic-Liassic volcanic sequence and rift evolution in the Saharan Atlas basins (Algeria). Eastward vanishing of the Central Atlantic magmatic province

Energy Technology Data Exchange (ETDEWEB)

Meddah, A.; Bertrand, H.; Seddiki, A.; Tabeliouna, M.

2017-11-01

We investigate the Triassic-Liassic sequence in ten diapirs from the Saharan Atlas (Algeria). Based on detailed mapping, two episodes are identified. The first one consists of a volcano-sedimentary sequence in which three volcanic units were identified (lower, intermediate and upper units). They are interlayered and sometimes imbricated with siliciclastic to evaporitic levels which record syn-sedimentary tectonics. This sequence was deposited in a lagoonal-continental environment and is assigned to the Triassic magmatic rifting stage. The second episode, lacking lava flows (post magmatic rifting stage), consists of carbonate levels deposited in a lagoonal to marine environment during the Rhaetian-Hettangian. The volcanic units consist of several thin basaltic flows, each 0.5 to 1m thick, with a total thickness of 10–15m. The basalts are low-Ti continental tholeiites, displaying enrichment in large ion lithophile elements and light rare earth elements [(La/Yb)n= 2.5-6] with a negative Nb anomaly. Upwards decrease of light-rare-earth-elements enrichment (e.g. La/Yb) is modelled through increasing melting rate of a spinel-bearing lherzolite source from the lower (6–10wt.%) to the upper (15–20wt.%) unit. The lava flows from the Saharan Atlas share the same geochemical characteristics and evolution as those from the Moroccan Atlas assigned to the Central Atlantic magmatic province. They represent the easternmost witness of this large igneous province so far known.

The Triassic-Liassic volcanic sequence and rift evolution in the Saharan Atlas basins (Algeria). Eastward vanishing of the Central Atlantic magmatic province

International Nuclear Information System (INIS)

Meddah, A.; Bertrand, H.; Seddiki, A.; Tabeliouna, M.

2017-01-01

We investigate the Triassic-Liassic sequence in ten diapirs from the Saharan Atlas (Algeria). Based on detailed mapping, two episodes are identified. The first one consists of a volcano-sedimentary sequence in which three volcanic units were identified (lower, intermediate and upper units). They are interlayered and sometimes imbricated with siliciclastic to evaporitic levels which record syn-sedimentary tectonics. This sequence was deposited in a lagoonal-continental environment and is assigned to the Triassic magmatic rifting stage. The second episode, lacking lava flows (post magmatic rifting stage), consists of carbonate levels deposited in a lagoonal to marine environment during the Rhaetian-Hettangian. The volcanic units consist of several thin basaltic flows, each 0.5 to 1m thick, with a total thickness of 10–15m. The basalts are low-Ti continental tholeiites, displaying enrichment in large ion lithophile elements and light rare earth elements [(La/Yb)n= 2.5-6] with a negative Nb anomaly. Upwards decrease of light-rare-earth-elements enrichment (e.g. La/Yb) is modelled through increasing melting rate of a spinel-bearing lherzolite source from the lower (6–10wt.%) to the upper (15–20wt.%) unit. The lava flows from the Saharan Atlas share the same geochemical characteristics and evolution as those from the Moroccan Atlas assigned to the Central Atlantic magmatic province. They represent the easternmost witness of this large igneous province so far known.

Sedimentary architecture and chronostratigraphy of a late Quaternary incised-valley fill: A case study of the late Middle and Late Pleistocene Rhine system in the Netherlands

Science.gov (United States)

Peeters, J.; Busschers, F. S.; Stouthamer, E.; Bosch, J. H. A.; Van den Berg, M. W.; Wallinga, J.; Versendaal, A. J.; Bunnik, F. P. M.; Middelkoop, H.

2016-01-01

This paper describes the sedimentary architecture, chronostratigraphy and palaeogeography of the late Middle and Late Pleistocene (Marine Isotope Stage/MIS 6-2) incised Rhine-valley fill in the central Netherlands based on six geological transects, luminescence dating, biostratigraphical data and a 3D geological model. The incised-valley fill consists of a ca. 50 m thick and 10-20 km wide sand-dominated succession and includes a well-developed sequence dating from the Last Interglacial: known as the Eemian in northwest Europe. The lower part of the valley fill contains coarse-grained fluvio-glacial and fluvial Rhine sediments that were deposited under Late Saalian (MIS 6) cold-climatic periglacial conditions and during the transition into the warm Eemian interglacial (MIS 5e-d). This unit is overlain by fine-grained fresh-water flood-basin deposits, which are transgressed by a fine-grained estuarine unit that formed during marine high-stand. This ca. 10 m thick sequence reflects gradual drowning of the Eemian interglacial fluvial Rhine system and transformation into an estuary due to relative sea-level rise. The chronological data suggests a delay in timing of regional Eemian interglacial transgression and sea-level high-stand of several thousand years, when compared to eustatic sea-level. As a result of this glacio-isostatic controlled delay, formation of the interglacial lower deltaic system took only place for a relative short period of time: progradation was therefore limited. During the cooler Weichselian Early Glacial period (MIS 5d-a) deposition of deltaic sediments continued and extensive westward progradation of the Rhine system occurred. Major parts of the Eemian and Weichselian Early Glacial deposits were eroded and buried as a result of sea-level lowering and climate cooling during the early Middle Weichselian (MIS 4-3). Near complete sedimentary preservation occurred along the margins of the incised valley allowing the detailed reconstruction presented

Late Quaternary sedimentary dynamics in Western Amazonia: Implications for the origin of open vegetation/forest contrasts

Science.gov (United States)

Rossetti, D. F.; Bertani, T. C.; Zani, H.; Cremon, E. H.; Hayakawa, E. H.

2012-12-01

This work investigated the evolution of sedimentary environments during the latest Quaternary and their influence on the paradoxical occurrence of open vegetation patches in sharp contact with the Amazonian forest. The approach integrated pre-existing geological and floristic data from lowlands in the Brazilian Amazonia, with remote sensing imagery including multispectral optical images (TM, ETM+, and ASTER), Phased Array L-band Synthetic Aperture Radar (PALSAR), InSAR C-band SRTM-DEMs, and high resolution images obtained from Google Earth™. The detection of an abundance of paleomorphologies provided evidence of a scenario in which constant environmental shifts were linked to the evolution of fluvial and megafan depositional systems. In all studied areas, the open vegetation patches are not random, but associated with sedimentary deposits representative of environments either deactivated during the Holocene or presently in the process of deactivation. Sedimentary evolution would have determined the distribution of wetlands and terra firme in many areas of the Amazonian lowlands, and would have a major impact on the development of open vegetated patches within the modern rainforest. Subsiding areas were filled up with megafan deposits, and many fluvial tributaries were rearranged on the landscape. The close relationship between vegetation and the physical environment suggests that sedimentary history related to the evolution of depositional settings during the latest Quaternary played a major role in the distribution of flooded and non-flooded areas of the Amazonian lowlands, with a direct impact on the distribution of modern floristic patterns. As the depositional sites were abandoned and their sedimentary deposits were exposed to the surface, they became sites suitable for vegetation growth, first of herbaceous species and then of forest. Although climate fluctuations might have been involved, fault reactivation appears to have been the main cause of changes in

Pervaja ledi, Afrika i skeletõ / Marina Mironova

Index Scriptorium Estoniae

Mironova, Marina

2006-01-01

Endine põllumajandusminister Ivari Padar loodab, et presidendiks valitud Toomas Hendrik Ilves suudab maaelu arengusse uusi tuuli tuua, presidendi abikaasa Evelin Ilves peab oma edaspidisteks kohustusteks tegelda heategevusega, hoolitseda oma pere eest ning jääda presidendi kõrval tahaplaanile

Precise natural radiography of seafloor sedimentary cores by using imaging plate

International Nuclear Information System (INIS)

Sugihara, Makoto; Tsuchiya, Noriyoshi

2007-01-01

The radiation measurement for seafloor sedimentary cores was carried out by using the Imaging Plate (IP). The precise natural radiography was obtained with 48 hours (exposure time) in a shield box. Layered structures of seafloor sediments that have relatively low radioactivity like biogenic matters could be detected by autoradiography, and it was possible to identify optically unclear layers of sediments with differences of radiation characteristics. The detection limit of thickness of suspended particle layers like volcanic ashes might be sub millimeters. It was possible to identify the pinpoint position where radioactive mineral emitted α-rays at the surface of sample. Identification of pinpoint position could be possible suppose radioactive minerals that emits α-ray exposed at the surface of sample. Distribution of dose (PSL value of IP) was related to CT value (X-ray CT), which indicates dose of sedimentary core have relationships with density and atomic number of sediments. The natural radiography for seafloor sediments cores by using the Imaging Plate is considered to be a powerful new tool as a non-destructive core analysis. (author)

Factors influencing the biogeochemistry of sedimentary carbon and phosphorus in the Sacramento-San Joaquin Delta

Science.gov (United States)

Nilsen, E.B.; Delaney, M.L.

2005-01-01

This study characterizes organic carbon (Corganic) and phosphorus (P) geochemistry in surface sediments of the Sacramento-San Joaquin Delta, California. Sediment cores were collected from five sites on a sample transect from the edge of the San Francisco Bay eastward to the freshwater Consumnes River. The top 8 cm of each core were analyzed (in 1-cm intervals) for Corganic, four P fractions, and redox-sensitive trace metals (uranium and manganese). Sedimentary Corganic concentrations and Corganic:P ratios decreased, while reactive P concentrations increased moving inland in the Delta. The fraction of total P represented by organic P increased inland, while that of authigenic P was higher bayward than inland reflecting increased diagenetic alteration of organic matter toward the bayward end of the transect. The redox indicator metals are consistent with decreasing sedimentary suboxia inland. The distribution of P fractions and C:P ratios reflect the presence of relatively labile organic matter in upstream surface sediments. Sediment C and P geochemistry is influenced by site-specific particulate organic matter sources, the sorptive power of the sedimentary material present, physical forcing, and early diagenetic transformations presumably driven by Corganic oxidation. ?? 2005 Estuarine Research Federation.

Mineralogy and depositional sources of sedimentary interbeds beneath the Idaho National Engineering Laboratory; eastern Snake River Plain, Idaho

International Nuclear Information System (INIS)

Reed, M.F.

1994-01-01

Idaho State University, in cooperation with the U.S. Geological Survey, and the U.S. Department of Energy, collected 57 samples of sedimentary interbeds at 19 sites at the Idaho National Engineering Laboratory (INEL) for mineralogical analysis. Previous work by the U.S. Geological Survey on surficial sediments showed that ratios detrital of quartz, total feldspars, and calcite can be used to distinguish the sedimentary mineralogy of specific stream drainages at the INEL. Semi-quantitative x-ray diffraction analyses were used to determine mineral abundances in the sedimentary interbeds. Samples were collected from wells at the New Production Reactor (NPR) area, Idaho Chemical Processing Plant (ICPP), Test Reactor Area (TRA), miscellaneous sites, Radioactive Waste Management Complex (RWMC), Naval Reactors Facility (NRF), and Test Area North (TAN). Normalized mean percentages of quartz, feldspar, and carbonate were calculated from sample data sets at each site. Percentages for quartz, feldspar, and carbonate from the NPR, ICPP, TRA, miscellaneous sites, RWMC, and NRF ranged from 37 to 59, 26 to 40, and 5 to 25, respectively. Percentages for quartz, feldspar, and carbonate from wells at Test Area North (TAN) were 24, 10, and 66, respectively. Mineralogical data indicate that sedimentary interbed samples collected from the NPR, ICPP, TRA, miscellaneous sites, RWMC, and NRF correlate with surficial sediment samples from the present day Big Lost River. Sedimentary interbeds from TAN sites correlate with surficial sediment samples from Birch Creek. These correlations suggest that the sources for the sediments at and near the INEL have remained relatively consistent for the last 580,000 years. 12 refs., 4 figs., 3 tabs

Spatial sedimentary distribution, seasonality and the characteristics of organic matter on Fernando de Noronha insular shelf

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Roberto Lima Barcellos

Full Text Available Abstract The present study was conducted in the Fernando de Noronha archipelago (4°S/32°W. The objective is the evaluation of the spatial distribution and seasonal variations in the sediments and sedimentary organic matter in the northern insular shelf of Fernando de Noronha ("Mar de Dentro". Nineteen surface sediment samples were collected between December 2013, July 2014 and November 2014. The studied methods included analysis of the grain size, coarse fraction, morphoscopy, total organic matter content, calcium carbonate, organic carbon, total nitrogen, sedimentary phosphorus (organic, inorganic and total, elemental ratios (C/N, C/P and stable isotopic ratios (δ13C-δ15N. The results allowed to infer that there is no seasonal variation in sediment distribution. Whereas, the shelf sediments present a calcareous sandy sedimentary cover (CaCO3≈ 88.3%, predominantly of well-sorted fine sands, with low organic matter content (TOM3.0%; TN>0.4% of mixed origin (δ13C= -24.5 to -23.0%PDB, which were related to anthropogenic impacts and the biotic and abiotic local processes.

Advancements in Exploration and In-Situ Recovery of Sedimentary-Hosted Uranium

International Nuclear Information System (INIS)

Maerten, Horst; Marsland-Smith, Andrea; Ross, Jonathan; Haschke, Michael; Kalka, Harald; Schubert, Jens

2014-01-01

Context and Outline: • ISR feasibility – determining factors: – What counts?; • High-resolution shallow seismic: – Methodology from ‘oil & gas hunting’ adapted to mineral exploration in sedimentary basins; • New down-hole logging tool: – Advanced PFN technology combined with lithologic logging; • Moving theory to practice: – Reactive-transport modelling for optimizing ISR

Granulometric analyses of pelites using a sedigraph: Examples from a Volcano-sedimentary environment

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas, A.

This article presents granulometric data of pelites (less than 40 microns) of mixed composition from a volcano-sedimentary environment. The sedigraph serves as an useful tool in the analyses of silt-clay fraction of marine sediments. A cumulative...

Recent benthic foraminifera and sedimentary facies distribution of the Abu Dhabi (United Arab Emirates) coastline

Science.gov (United States)

Fiorini, Flavia; Lokier, Stephen W.

2014-05-01

The distribution of benthic foraminifera and sedimentary facies from Recent coastline environments adjacent to the coastline of Abu Dhabi (UAE) was studied in detail with the aim to: 1) provide reliable analogs for understanding and interpreting the depositional environment of ancient shallow-marine sediments from the UAE; 2) assess any modifications in the distribution of benthic environments and sedimentary facies in an area affected by significant anthropogenic activities - particular construction and land reclamation. A total of 100 sea-floor sediment samples were collected in different shallow-marine sedimentary environments (nearshore shelf, beach-front, channels, ooid shoals, lagoon and mangals) close to the coastline of Abu Dhabi Island. Where possible, we revisited the sampling sites used in several studies conducted in the middle of last century (prior to any significant anthropogenic activities) to assess temporal changes in Recent benthic foraminifera and sedimentary facies distribution during the last 50 years. Five foraminiferal assemblages were recognized in the studied area. Species with a porcellaneous test mainly belonging to the genera Quinqueloculina, Triloculina, Spiroloculina, Sigmoilinita are common in all studied areas. Larger benthic foraminifera Peneroplis and Spirolina are particularly abundant in samples collected on seaweed. Hyaline foraminifera mostly belonging to the genera Elphidium, Ammonia, Bolivina and Rosalina are also common together with Miliolidae in the nearshore shelf and beach front. Agglutinated foraminifera (Clavulina, Textularia, Ammobaculites and Reophax) are present in low percentages. The species belonging to the genera Ammobaculites and Reophax are present only in the finest grain samples particularly in lagoons and mangal environments and have not been reported previously in the studied area. The majority of the ooid shoal sediments, the coarser sediments of the beach-front and samples collected in dredged channels

Origin of planation surfaces in the hinterland of Šumljak sedimentary bodies in Rebrnice (Upper Vipava Valley, SW Slovenia

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Tomislav Popit

2017-12-01

Full Text Available The Rebrnice area forms the north eastern slopes of the Upper Vipava Valley and is located between Karst plateau to the southwest and the Nanos plateau to the northeast. The Rebrnice slopes are geomorphologically defied by a thrust front of Mesozoic carbonates over Tertiary flsch deposits and are characterised by a variety of polygenetic landslides (being the most prominent geomorphological features. Among them, the three Šumljak sedimentary bodies of fossil landslides (approximately 0.56 km² in area comprise carbonate gravels and breccia. The most distinctive geomorphological element is the planation surface of the carbonate breccia blocks positioned in the hinterland of the Šumljak sedimentary bodies. Another feature is the presence of local escarpments (steep scarps defiing the border between the planation surface in the hinterland and sedimentary bodies. Our research suggests that the whole area in the hinterland of the Šumljak sedimentary bodies form part of a deep-seated rotational landslide formed of carbonate breccia. On the basis of the dipping of the breccia beds, in particular parts of the rotational blocks, the rotation can reach up to 60°. Planation surfaces developed above the curved, sliding plane in the central part and/or slightly outer part of the landslide. Steep scarps on the external parts of the planation surface represent the main scarps of the Šumljak sedimentary bodies. We propose that these bodies originated from the remobilization of material accumulated in outer parts of large-scale rotational slides and its transportation further downslope, mostly by rock avalanches.

Sedimentary gravity flows from subaerial fan-deltas in Loreto Bay, Baja California Sur, Mexico

Science.gov (United States)

Navarro-Lozano, José O.; Nava-Sánchez, Enrique H.; Godínez-Orta, Lucio

2010-05-01

Fan-deltas from Loreto Bay show recent evidences of sedimentary gravity flows as a result from catastrophic events during hurricane rainfalls. The knowledge of hydrological characteristics of these flows is important for understanding the effects of storms on fan-deltas geomorphology in this region, as well as for the urban developing planning of the city of Loreto in order to avoid hazardous zones. The analysis of precipitation and hurricane tracks data for the period 1945 to 2009 indicates that hurricanes have caused catastrophic floods every 20 years. Stratigraphy from the channel incision shows a sequence of stream flow and debris flow controlled by changes in the competence and capacity of the stream, which are associated to the gentle slope (<2 °) of the fan-deltas. However fans from the north of the bay (Arce and Gúa) show deposits of debris flows associated to catastrophic floods, which have caused the incision channel to drift towards the southern part of the fans, while flows from Las Parras fan-delta, from the middle of the bay, are dominated by stream flows. These differences in the type of the flows are controlled by lithology, shape and size of the drainage basin, and slope of the transit zone in the feeder channel.

Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary and Crystalline Formations

Energy Technology Data Exchange (ETDEWEB)

Bruno, Mike S. [Terralog Technologies USA, Inc., Calgary (Canada); Detwiler, Russell L. [Terralog Technologies USA, Inc., Calgary (Canada); Lao, Kang [Terralog Technologies USA, Inc., Calgary (Canada); Serajian, Vahid [Terralog Technologies USA, Inc., Calgary (Canada); Elkhoury, Jean [Terralog Technologies USA, Inc., Calgary (Canada); Diessl, Julia [Terralog Technologies USA, Inc., Calgary (Canada); White, Nicky [Terralog Technologies USA, Inc., Calgary (Canada)

2012-12-13

There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. The primary objectives of this DOE research effort are to develop and document optimum design configurations and operating practices to produce geothermal power from hot permeable sedimentary and crystalline formations using advanced horizontal well recirculation systems. During Phase I of this research project Terralog Technologies USA and The University of California, Irvine (UCI), have completed preliminary investigations and documentation of advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. We have also identified significant geologic resources appropriate for application of such technology. The main challenge for such recirculation systems is to optimize both the design configuration and the operating practices for cost-effective geothermal energy recovery. These will be strongly influenced by sedimentary formation properties, including thickness and dip, temperature, thermal conductivity, heat capacity, permeability, and porosity; and by working fluid properties.

Gravitational dislocations of sedimentary deposits in southern UkSSR

Energy Technology Data Exchange (ETDEWEB)

Belokrys, L S

1980-01-01

Characteristics of several types of dislocations are presented: pseudosynclines in Pontian deposits, and fracture dislocations; brachy-syncline subsidence folds; protrusion folds and their relics (easily diagnosed landslide faults). It is shown that two circumstances govern local folding and fracture faults in horizontally bedded sedimentary deposits in the southern Ukraine: 1) the alternation of competent and incompetent deposits in the fault, 2) the increasing unevenness of the static burden on the plastic layers as the erosion network grows. These faults are undoubtedly linked with geomorphological, not tectonic, elements.

The role of deep-water sedimentary processes in shaping a continental margin: The Northwest Atlantic

Science.gov (United States)

Mosher, David C.; Campbell, D.C.; Gardner, J.V.; Piper, D.J.W.; Chaytor, Jason; Rebesco, M.

2017-01-01

The tectonic history of a margin dictates its general shape; however, its geomorphology is generally transformed by deep-sea sedimentary processes. The objective of this study is to show the influences of turbidity currents, contour currents and sediment mass failures on the geomorphology of the deep-water northwestern Atlantic margin (NWAM) between Blake Ridge and Hudson Trough, spanning about 32° of latitude and the shelf edge to the abyssal plain. This assessment is based on new multibeam echosounder data, global bathymetric models and sub-surface geophysical information.The deep-water NWAM is divided into four broad geomorphologic classifications based on their bathymetric shape: graded, above-grade, stepped and out-of-grade. These shapes were created as a function of the balance between sediment accumulation and removal that in turn were related to sedimentary processes and slope-accommodation. This descriptive method of classifying continental margins, while being non-interpretative, is more informative than the conventional continental shelf, slope and rise classification, and better facilitates interpretation concerning dominant sedimentary processes.Areas of the margin dominated by turbidity currents and slope by-pass developed graded slopes. If sediments did not by-pass the slope due to accommodation then an above grade or stepped slope resulted. Geostrophic currents created sedimentary bodies of a variety of forms and positions along the NWAM. Detached drifts form linear, above-grade slopes along their crests from the shelf edge to the deep basin. Plastered drifts formed stepped slope profiles. Sediment mass failure has had a variety of consequences on the margin morphology; large mass-failures created out-of-grade profiles, whereas smaller mass failures tended to remain on the slope and formed above-grade profiles at trough-mouth fans, or nearly graded profiles, such as offshore Cape Fear.

A refined model of sedimentary rock cover in the southeastern part of the Congo basin from GOCE gravity and vertical gravity gradient observations

Science.gov (United States)

Martinec, Zdeněk; Fullea, Javier

2015-03-01

We aim to interpret the vertical gravity and vertical gravity gradient of the GOCE-GRACE combined gravity model over the southeastern part of the Congo basin to refine the published model of sedimentary rock cover. We use the GOCO03S gravity model and evaluate its spherical harmonic representation at or near the Earth's surface. In this case, the gradiometry signals are enhanced as compared to the original measured GOCE gradients at satellite height and better emphasize the spatial pattern of sedimentary geology. To avoid aliasing, the omission error of the modelled gravity induced by the sedimentary rocks is adjusted to that of the GOCO03S gravity model. The mass-density Green's functions derived for the a priori structure of the sediments show a slightly greater sensitivity to the GOCO03S vertical gravity gradient than to the vertical gravity. Hence, the refinement of the sedimentary model is carried out for the vertical gravity gradient over the basin, such that a few anomalous values of the GOCO03S-derived vertical gravity gradient are adjusted by refining the model. We apply the 5-parameter Helmert's transformation, defined by 2 translations, 1 rotation and 2 scale parameters that are searched for by the steepest descent method. The refined sedimentary model is only slightly changed with respect to the original map, but it significantly improves the fit of the vertical gravity and vertical gravity gradient over the basin. However, there are still spatial features in the gravity and gradiometric data that remain unfitted by the refined model. These may be due to lateral density variation that is not contained in the model, a density contrast at the Moho discontinuity, lithospheric density stratifications or mantle convection. In a second step, the refined sedimentary model is used to find the vertical density stratification of sedimentary rocks. Although the gravity data can be interpreted by a constant sedimentary density, such a model does not correspond to

Use of ancient sedimentary DNA as a novel conservation tool for high-altitude tropical biodiversity.

Science.gov (United States)

Boessenkool, Sanne; McGlynn, Gayle; Epp, Laura S; Taylor, David; Pimentel, Manuel; Gizaw, Abel; Nemomissa, Sileshi; Brochmann, Christian; Popp, Magnus

2014-04-01

Conservation of biodiversity may in the future increasingly depend upon the availability of scientific information to set suitable restoration targets. In traditional paleoecology, sediment-based pollen provides a means to define preanthropogenic impact conditions, but problems in establishing the exact provenance and ecologically meaningful levels of taxonomic resolution of the evidence are limiting. We explored the extent to which the use of sedimentary ancient DNA (sedaDNA) may complement pollen data in reconstructing past alpine environments in the tropics. We constructed a record of afro-alpine plants retrieved from DNA preserved in sediment cores from 2 volcanic crater sites in the Albertine Rift, eastern Africa. The record extended well beyond the onset of substantial anthropogenic effects on tropical mountains. To ensure high-quality taxonomic inference from the sedaDNA sequences, we built an extensive DNA reference library covering the majority of the afro-alpine flora, by sequencing DNA from taxonomically verified specimens. Comparisons with pollen records from the same sediment cores showed that plant diversity recovered with sedaDNA improved vegetation reconstructions based on pollen records by revealing both additional taxa and providing increased taxonomic resolution. Furthermore, combining the 2 measures assisted in distinguishing vegetation change at different geographic scales; sedaDNA almost exclusively reflects local vegetation, whereas pollen can potentially originate from a wide area that in highlands in particular can span several ecozones. Our results suggest that sedaDNA may provide information on restoration targets and the nature and magnitude of human-induced environmental changes, including in high conservation priority, biodiversity hotspots, where understanding of preanthropogenic impact (or reference) conditions is highly limited. © 2013 Society for Conservation Biology.

Depositional History and Sequence Stratigraphy of the Middle Ordovician Yeongheung Formation (Yeongweol Group), Taebaeksan Basin, mid-east Korea

Science.gov (United States)

Kwon, Yoo Jin; Kwon, Yi Kyun

2017-04-01

The Middle Ordovician Yeongheung Formation consists of numerous meter-scale, shallowing-upward cycles which were deposited on a shallow-marine carbonate platform. Many diagnostic sedimentary textures and structures such as supratidal laminite, tepee structure, and solution-collapsed breccia are observed, which enable to infer the dry climate and high salinity conditions during deposition of the formation. In order to understand its depositional history, this study focuses on vertical and spatial stacking patterns of the second- to third-order sequences through the detailed outcrop description and geologic mapping. A total 19 lithofacies have been recognized, which can be grouped into 5 facies associations (FAs): FA1 (Supratidal flat), FA2 (Supratidal or dolomitization of peritidal facies), FA3 (Intertidal flat), FA4 (Shallow subtidal to peritidal platform), FA5 (Shallow subtidal shoal). Global mega-sequence boundary (Sauk-Tippecanoe) occurs in solution-collapsed breccia zone in the lower part of the formation. Correlation of the shallowing-upward cycle stacking pattern across the study area defines 6 transgressive-regressive depositional sequences. Each depositional sequences comprises a package of vertical and spatial staking of shallow subtidal cycles in the lower part and peritidal cycles in the upper part of the formation. According to sequence stratigraphic interpretation, the reconstructed relative sea-level curve of the Yeongweol platform is very similar to that of the Taebaek platform. Based on the absence of siliciclastic sequence such as the Jigunsan Formation and the lithologic & stratigraphic differences, however, the Yeongweol and Taebaek groups might not belong to a single depositional system within the North China platform. The Yeongweol Group can be divided by the four subunits into their unique lithologic successions and geographic distributions. The Eastern subunit of the Yeongweol Group is composed dominantly of carbonate rocks with a high

Ancient sedimentary structures in the Mars, that resemble macroscopic morphology, spatial associations, and temporal succession in terrestrial microbialites.

Science.gov (United States)

Noffke, Nora

2015-02-01

Sandstone beds of the Mars have been interpreted as evidence of an ancient playa lake environment. On Earth, such environments have been sites of colonization by microbial mats from the early Archean to the present time. Terrestrial microbial mats in playa lake environments form microbialites known as microbially induced sedimentary structures (MISS). On Mars, three lithofacies of the Gillespie Lake Member sandstone display centimeter- to meter-scale structures similar in macroscopic morphology to terrestrial MISS that include "erosional remnants and pockets," "mat chips," "roll-ups," "desiccation cracks," and "gas domes." The microbially induced sedimentary-like structures identified in Curiosity rover mission images do not have a random distribution. Rather, they were found to be arranged in spatial associations and temporal successions that indicate they changed over time. On Earth, if such MISS occurred with this type of spatial association and temporal succession, they would be interpreted as having recorded the growth of a microbially dominated ecosystem that thrived in pools that later dried completely: erosional pockets, mat chips, and roll-ups resulted from water eroding an ancient microbial mat-covered sedimentary surface; during the course of subsequent water recess, channels would have cut deep into the microbial mats, leaving erosional remnants behind; desiccation cracks and gas domes would have occurred during a final period of subaerial exposure of the microbial mats. In this paper, the similarities of the macroscopic morphologies, spatial associations, and temporal succession of sedimentary structures on Mars to MISS preserved on Earth has led to the following hypothesis: The sedimentary structures in the Mars are ancient MISS produced by interactions between microbial mats and their environment. Proposed here is a strategy for detecting, identifying, confirming, and differentiating possible MISS during current and future Mars missions.

Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

OpenAIRE

Linssen, J.H.

1991-01-01

In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its variations are recorded in rocks as a natural remanent magnetization (NRM) during the formation of these rocks. The study of the NRM in sedimentary reversal records is the subject of this dissertation.

Sedimentary records of past earthquakes in Boraboy Lake during the last ca 600 years (North Anatolian Fault, Turkey)

KAUST Repository

Avsar, Ulas

2015-05-21

Multiproxy sedimentological analyses along 4.9 m-long sequence of Boraboy Lake, which is located on the central eastern part of the North Anatolian Fault (NAF), reveal the sedimentary traces of past large earthquakes in the region. The lake has a relatively large catchment area (10 km2) compared to its size (0.12 km2), which renders sedimentation sensitive to heavy rain/storm events. Accordingly, the background sedimentation, which is composed of faintly laminated reddish/yellowish brown clayey silt, is frequently interrupted by organic-rich intercalations probably due to heavy rain/storm events transporting terrestrial plant remains from the densely vegetated catchment. In addition to frequent organic-rich intercalations, the background sedimentation is interrupted by four mass-wasting deposits (MWD) of which thickness range between 15 and 50 cm. High-resolution ITRAX μXRF data confirms higher homogeneity along the MWDs (E1-E4) compared to the background sedimentation. Based on 137Cs and 210Pbxs dating and radiocarbon chronology, three MWDs detected in Boraboy sequence (E2, E3 and E4) temporally correlate with large historical earthquakes along the NAF; the 1943 Tosya (Ms= 7.6) and/or 1942 Niksar-Erbaa (Ms= 7.1), the 1776 Amasya-Merzifon and the 1668 North Anatolian (Ms= 7.9) earthquakes. The youngest MWD in the sequence (E1), which is dated to early 2000s, does not correlate with any strong earthquake in the region. This MWD was probably a single mass-wasting event due to routine overloading and oversteepening on the delta front formed by the main inlet of the lake. In subaqueous paleoseismology, coevality of multi-location mass-wasting events is used as a criterion to assign a seismic triggering mechanism, and to rule out mass-wasting events due to routine overloading/oversteepening of subaqueous slopes. Within this context, Boraboy sequence provides a valuable example to discuss sedimentological imprints of single- vs. multi-source MWDs.

A multivariate geostatistical methodology to delineate areas of potential interest for future sedimentary gold exploration.

Science.gov (United States)

Goovaerts, P; Albuquerque, Teresa; Antunes, Margarida

2016-11-01

This paper describes a multivariate geostatistical methodology to delineate areas of potential interest for future sedimentary gold exploration, with an application to an abandoned sedimentary gold mining region in Portugal. The main challenge was the existence of only a dozen gold measurements confined to the grounds of the old gold mines, which precluded the application of traditional interpolation techniques, such as cokriging. The analysis could, however, capitalize on 376 stream sediment samples that were analyzed for twenty two elements. Gold (Au) was first predicted at all 376 locations using linear regression (R 2 =0.798) and four metals (Fe, As, Sn and W), which are known to be mostly associated with the local gold's paragenesis. One hundred realizations of the spatial distribution of gold content were generated using sequential indicator simulation and a soft indicator coding of regression estimates, to supplement the hard indicator coding of gold measurements. Each simulated map then underwent a local cluster analysis to identify significant aggregates of low or high values. The one hundred classified maps were processed to derive the most likely classification of each simulated node and the associated probability of occurrence. Examining the distribution of the hot-spots and cold-spots reveals a clear enrichment in Au along the Erges River downstream from the old sedimentary mineralization.

Tectono-sedimentary evolution of Erlian basin since late mesozoic and sandstone-hosted uranium metallogenesis

International Nuclear Information System (INIS)

Wei Sanyuan; Qin Mingkuan; Li Yuexiang; He Zhongbo; Chen Anping; Shen Kefeng; Cao Jianying

2006-01-01

Various mineral resources in a basin are associated with its tectono-sedimentary evolution. Based on the analysis of the tectono-sedimentary evolution of Erlian basin, three evolutional stages of Erlian basin are classified, they are: the continental extensional down-faulting stage, the transitional stage from down-faulting to down-warping in Early Cretaceous, and slightly compressional differentiated uplifting-subsidence since Late Cretaceous. According to the mechanism of sandstone-hosted uranium metallogenesis it is suggested that the grey clastic rock series deposited at the stage of down-faulting down-warping transition must be the important target for uranium prospecting, and the differentiated uplifting-subsidence offers necessary conditions for sandstone-hosted uranium ore-formation. Then, types of uranium mineralization that could occur in Erlian basin are discussed, and uranium metallogenic model has been preliminarily summarized. (authors)

Use of structural geology in exploration for and mining of sedimentary rock-hosted Au deposits

Science.gov (United States)

Peters, Stephen G.

2001-01-01

Structural geology is an important component in regional-, district- and orebody-scale exploration and development of sedimentary rock-hosted Au deposits.Identification of timing of important structural events in an ore district allows analysis and classification of fluid conduits and construction of genetic models for ore formation.The most practical uses of structural geology deal with measurement and definition of various elements that comprise orebodies, which can then be directly applied to ore-reserve estimation,ground control,grade control, safety issues,and mine planning.District- and regional-scale structural studies are directly applicable to long-term strategic planning,economic analysis,and land ownership. Orebodies in sedimentary rock-hosted Au deposits are discrete, hypogene, epigenetic masses usually hosted in a fault zone,breccia mass, or lithologic bed or unit. These attributes allow structural geology to be directly applied to the mining and exploration of sedimentary rock-hosted Au deposits. Internal constituents in orebodies reflect unique episodes relating to ore formation.The main internal constituents in orebodies are ore minerals, gangue, and alteration minerals that usually are mixed with one another in complex patterns, the relations among which may be used to interpret the processes of orebody formation and control.Controls of orebody location and shape usually are due to structural dilatant zones caused by changes in attitude, splays, lithologic contacts,and intersections of the host conduit or unit.In addition,conceptual parameters such as district fabric,predictable distances, and stacking also are used to understand the geometry of orebodies.Controls in ore districts and location and geometry of orebodies in ore districts can be predicted to various degrees by using a number of qualitative concepts such as internal and external orebody plunges,district plunge, district stacking, conduit classification, geochemical, geobarometric and

Excavatability Assessment of Weathered Sedimentary Rock Mass Using Seismic Velocity Method

International Nuclear Information System (INIS)

Bin Mohamad, Edy Tonnizam; Noor, Muhazian Md; Isa, Mohamed Fauzi Bin Md.; Mazlan, Ain Naadia; Saad, Rosli

2010-01-01

Seismic refraction method is one of the most popular methods in assessing surface excavation. The main objective of the seismic data acquisition is to delineate the subsurface into velocity profiles as different velocity can be correlated to identify different materials. The physical principal used for the determination of excavatability is that seismic waves travel faster through denser material as compared to less consolidated material. In general, a lower velocity indicates material that is soft and a higher velocity indicates more difficult to be excavated. However, a few researchers have noted that seismic velocity method alone does not correlate well with the excavatability of the material. In this study, a seismic velocity method was used in Nusajaya, Johor to assess the accuracy of this seismic velocity method with excavatability of the weathered sedimentary rock mass. A direct ripping run by monitoring the actual production of ripping has been employed at later stage and compared to the ripper manufacturer's recommendation. This paper presents the findings of the seismic velocity tests in weathered sedimentary area. The reliability of using this method with the actual rippability trials is also presented.

Excavatability Assessment of Weathered Sedimentary Rock Mass Using Seismic Velocity Method

Science.gov (United States)

Bin Mohamad, Edy Tonnizam; Saad, Rosli; Noor, Muhazian Md; Isa, Mohamed Fauzi Bin Md.; Mazlan, Ain Naadia

2010-12-01

Seismic refraction method is one of the most popular methods in assessing surface excavation. The main objective of the seismic data acquisition is to delineate the subsurface into velocity profiles as different velocity can be correlated to identify different materials. The physical principal used for the determination of excavatability is that seismic waves travel faster through denser material as compared to less consolidated material. In general, a lower velocity indicates material that is soft and a higher velocity indicates more difficult to be excavated. However, a few researchers have noted that seismic velocity method alone does not correlate well with the excavatability of the material. In this study, a seismic velocity method was used in Nusajaya, Johor to assess the accuracy of this seismic velocity method with excavatability of the weathered sedimentary rock mass. A direct ripping run by monitoring the actual production of ripping has been employed at later stage and compared to the ripper manufacturer's recommendation. This paper presents the findings of the seismic velocity tests in weathered sedimentary area. The reliability of using this method with the actual rippability trials is also presented.

Estimate of the Geothermal Energy Resource in the Major Sedimentary Basins in the United States (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Esposito, A.; Porro, C.; Augustine, C.; Roberts, B.

2012-09-01

Because most sedimentary basins have been explored for oil and gas, well logs, temperatures at depth, and reservoir properties such as depth to basement and formation thickness are well known. The availability of this data reduces exploration risk and allows development of geologic exploration models for each basin. This study estimates the magnitude of recoverable geothermal energy from 15 major known U.S. sedimentary basins and ranks these basins relative to their potential. The total available thermal resource for each basin was estimated using the volumetric heat-in-place method originally proposed by (Muffler, 1979). A qualitative recovery factor was determined for each basin based on data on flow volume, hydrothermal recharge, and vertical and horizontal permeability. Total sedimentary thickness maps, stratigraphic columns, cross sections, and temperature gradient information was gathered for each basin from published articles, USGS reports, and state geological survey reports. When published data were insufficient, thermal gradients and reservoir properties were derived from oil and gas well logs obtained on oil and gas commission databases. Basin stratigraphy, structural history, and groundwater circulation patterns were studied in order to develop a model that estimates resource size, temperature distribution, and a probable quantitative recovery factor.

Two-dimensional simulation of clastic and carbonate sedimentation, consolidation, subsidence, fluid flow, heat flow and solute transport during the formation of sedimentary basins

Science.gov (United States)

Bitzer, Klaus

1999-05-01

Script format: BASINVIEW is used to display the distribution of parameters in the simulated cross-section of the basin for defined time steps. It is used in conjunction with the Ghostview software, which is freeware and available on most computer systems. AIBASIN provides PostScript output for Adobe Illustrator®, taking advantage of the layer-concept which facilitates further graphic manipulation. BASELINE is used to display parameter distribution at a defined well or to visualize the temporal evolution of individual elements located in the simulated sedimentary basin. The modular structure of the BASIN code allows additional processes to be included. A module to simulate reactive transport and diagenetic reactions is planned for future versions. The program has been applied to existing sedimentary basins, and it has also shown a high potential for classroom instruction, giving the possibility to create hypothetical basins and to interpret basin evolution in terms of sequence stratigraphy or petroleum potential.

Sedimentary manganese metallogenesis in response to the evolution of the Earth system

Science.gov (United States)

Roy, Supriya

2006-08-01

The concentration of manganese in solution and its precipitation in inorganic systems are primarily redox-controlled, guided by several Earth processes most of which were tectonically induced. The Early Archean atmosphere-hydrosphere system was extremely O 2-deficient. Thus, the very high mantle heat flux producing superplumes, severe outgassing and high-temperature hydrothermal activity introduced substantial Mn 2+ in anoxic oceans but prevented its precipitation. During the Late Archean, centered at ca. 2.75 Ga, the introduction of Photosystem II and decrease of the oxygen sinks led to a limited buildup of surface O 2-content locally, initiating modest deposition of manganese in shallow basin-margin oxygenated niches (e.g., deposits in India and Brazil). Rapid burial of organic matter, decline of reduced gases from a progressively oxygenated mantle and a net increase in photosynthetic oxygen marked the Archean-Proterozoic transition. Concurrently, a massive drawdown of atmospheric CO 2 owing to increased weathering rates on the tectonically expanded freeboard of the assembled supercontinents caused Paleoproterozoic glaciations (2.45-2.22 Ga). The spectacular sedimentary manganese deposits (at ca. 2.4 Ga) of Transvaal Supergroup, South Africa, were formed by oxidation of hydrothermally derived Mn 2+ transferred from a stratified ocean to the continental shelf by transgression. Episodes of increased burial rate of organic matter during ca. 2.4 and 2.06 Ga are correlatable to ocean stratification and further rise of oxygen in the atmosphere. Black shale-hosted Mn carbonate deposits in the Birimian sequence (ca. 2.3-2.0 Ga), West Africa, its equivalents in South America and those in the Francevillian sequence (ca. 2.2-2.1 Ga), Gabon are correlatable to this period. Tectonically forced doming-up, attenuation and substantial increase in freeboard areas prompted increased silicate weathering and atmospheric CO 2 drawdown causing glaciation on the Neoproterozoic Rodinia

A detailed paleomagnetic and rock-magnetic investigation of the Matuyama-Bruhnes geomagnetic reversal recorded in tephra-paleosol sequence of Tlaxcala(Central Mexico

Directory of Open Access Journals (Sweden)

Ana Maria Soler-Arechalde

2015-04-01

Full Text Available Geomagnetic reversals are global phenomena, for about 50 years the paleomagnetists attempted to acquire as many detailed records as possible using the magnetic memory of sediments and lava flows. Yet, transitional field behavior remains poorly characterized largely because of sporadic aspect of volcanic eruptions. In some specific cases, paleosols such as those developed from alluvial or aeolian sediments, may also record the variations of the Geomagnetic Field across the polarity changes. Here, we report a detailed paleomagnetic and rock-magnetic investigation on some radiometrically dated chromic luvisols located in Central Mexico carrying detrital or chemical remanent magnetization. The research was developed in order i to demonstrate the primary origin of the magnetic remanence and ii to show that paleosoils are good candidates to provide a high resolution record of the behavior of geomagnetic field during reversals. The lower part of the paleosoil sequence shows a clearly defined reverse polarity magnetization followed by geomagnetically unstable transitional field and ended by normal polarity remanence. Our AMS and rock magnetic data suggest that magnetization is acquired during the initial stage of soil formation in context of active volcanic activity since magnetic fabric is essentially sedimentary and reverse and normal polarity paleodirections are almost antipodal. Titanomagnetites are identified as main magnetic carriers of rock-magnetic measurements including thermomagnetics and hysteresis cycles. We propose that the transition recorded in this study correspond to the B-M boundary, considering the K-Ar datings available at the sequence bottom and that the chromic luvisols are potentially good recorders of the paleosecular variation. The identification of the B-M boundary within the studied sequence has fundamental significance for improving the chronological scale of Tlaxcala paleosol-sedimentary sequence and its correlation with the

The Hidden Watershed's Journals: the Informational Characteristics of Biomarkers in Sedimentary Deposits

Science.gov (United States)

Guerrero, F. J.; Hatten, J. A.

2014-12-01

The historical reconstruction of past environmental changes in watersheds is essential to understand watershed response to disturbances and how those diturbances could affect the provision of valuable goods like water. That reconstruction requires the interpretation of natural records, mainly associated to sedimentary deposits that store detailed information in the form of specific biogenic molecules (i.e. biomarkers). In forested watersheds terrestrial vegetation is an important source of biomarkers like those associated to Lignin, a complex organic polymer used by plants to provide physical support in its tissues. Through litter inputs Lignin is deposited in soils and then is transported to sedimentary environments by rivers (e.g. floodplains, lake bottoms), serving as a source of information about vegetation changes in watersheds. In spite of the critical character of the information extracted from biomarkers in sedimentary records, the very concept of information is still used in a metaphorical sense, even though it was formally defined more than 60 years ago and has been applied extensively in ecology (e.g. Shannon's diversity index). Furthermore, sophisticated techniques are being used to deliver more complex molecular data that require examination and validation as indicators for watershed historical reconstructions. My research aims to explore the applicability of some information metrics (i.e. diversity indices, information coefficients) to a diverse molecular set derived from the chemical depolymerization of lignin deposited in floodplains and lake sediments in different basins. This approach attempts to assess the informational characteristics of Lignin as an indicator of natural/human-induced perturbations in forested watersheds. The formal assessment of the informational characteristics of natural records could have a profound impact not only in our methodological approaches but also in our philosophical view about information and communication in

Tectonics and sedimentary process in the continental talud in Uruguay

International Nuclear Information System (INIS)

De Santa Ana, H.; Soto, M.; Morales, E.; Tomasini, J.; Hernandez-Molina, F.; Veroslavsky, G.

2012-01-01

The morphology and evolution of the continental margin of Uruguay is due to the interaction of an important set of sedimentary processes. The contourite and turbiditic are the most significant processes which are associated with the development of submarine canyons as well as the gravitational mass respect to major landslides. These processes generate erosional and depositional features with a direct impact on different areas of application, which have potential environmental risks (gravitational landslides, earthquakes, tsunamis) and potential economic resources

The Eocene-Oligocene sedimentary record in the Chesapeake Bay impact structure: Implications for climate and sea-level changes on the western Atlantic margin

Science.gov (United States)

Schulte, P.; Wade, B.S.; Kontny, A.; ,

2009-01-01

A multidisciplinary investigation of the Eocene-Oligocene transition in the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville core from the Chesapeake Bay impact basin was conducted in order to document environmental changes and sequence stratigraphic setting. Planktonic foraminifera and calcareous nannofossil biostratigraphy indicate that the Eyreville core includes an expanded upper Eocene (Biozones E15 to E16 and NP19/20 to NP21, respectively) and a condensed Oligocene-Miocene (NP24-NN1) sedimentary sequence. The Eocene-Oligocene contact corresponds to a =3-Ma-long hiatus. Eocene- Oligocene sedimentation is dominated by great diversity and varying amounts of detrital and authigenic minerals. Four sedimentary intervals are identified by lithology and mineral content: (1) A 30-m-thick, smectite- and illite-rich interval directly overlies the Exmore Formation, suggesting long-term reworking of impact debris within the Chesapeake Bay impact structure. (2) Subsequently, an increase in kaolinite content suggests erosion from soils developed during late Eocene warm and humid climate in agreement with data derived from other Atlantic sites. However, the kaolinite increase may also be explained by change to a predominant sediment input from outside the Chesapeake Bay impact structure caused by progradation of more proximal facies belts during the highstand systems tract of the late Eocene sequence E10.Spectral analysis based on gamma-ray and magnetic susceptibility logs suggests infl uence of 1.2 Ma low-amplitude oscillation of the obliquity period during the late Eocene. (3) During the latest Eocene (Biozones NP21 and E16), several lithological contacts (clay to clayey silt) occur concomitant with a prominent change in the mineralogical composition with illite as a major component: This lithological change starts close to the Biozone NP19/20-NP21 boundary and may correspond to sequence boundary E10-E11 as observed in

Sedimentary features of the Mercedes formation (upper Cretaceous ) between Mercedes and Fray Bentos cities, Rca. O del Uruguay

International Nuclear Information System (INIS)

Tofalo, O.; Pazos, P.

1998-01-01

A new locality by the Mercedes formation is analyzed close to route 2, near at the Mercedes City. The stratigraphic assignment is proposed after the examination of the sedimentary features that include geometry, composition and sedimentary structures. The section that reach 10 meters in thickness contains conglomerates, pebbly sandstones, sandstones and scare mudstones with a finning upward arrangement. All of features are indicative of a alluvial origin. This locality is the first mention of the Mercedes formation in the south section of the Department Rio Negro. (author)

The Early to Middle Triassic continental–marine transition of NW Bulgaria: sedimentology, palynology and sequence stratigraphy

Directory of Open Access Journals (Sweden)

Ajdanlijsky George

2018-04-01

Full Text Available Sedimentary facies and cycles of the Triassic continental–marine transition of NW Bulgaria are documented in detail from reference sections along the Iskar river gorge between the villages of Tserovo and Opletnya. The depositional environments evolved from anastomosing and meandering river systems in the Petrohan Terrigenous Group to mixed fluvial and tidal settings in the Svidol Formation, and to peritidal and shallow-marine conditions in the Opletnya Member of the Mogila Formation. For the first time, the palynostratigraphic data presented here allow for dating the transitional interval and for the precise identification of a major sequence boundary between the Petrohan Terrigenous Group and the Svidol Formation (Iskar Carbonate Group. This boundary most probably corresponds to the major sequence boundary Ol4 occurring in the upper Olenekian of the Tethyan realm and thus enables interregional correlation. The identification of regionally traceable sequence boundaries based on biostratigraphic age control is a first step towards a more accurate stratigraphic correlation and palaeogeographic interpretation of the Early to early Middle Triassic in NW Bulgaria.

The Early to Middle Triassic continental-marine transition of NW Bulgaria: sedimentology, palynology and sequence stratigraphy

Science.gov (United States)

Ajdanlijsky, George; Götz, Annette E.; Strasser, André

2018-04-01

Sedimentary facies and cycles of the Triassic continental-marine transition of NW Bulgaria are documented in detail from reference sections along the Iskar river gorge between the villages of Tserovo and Opletnya. The depositional environments evolved from anastomosing and meandering river systems in the Petrohan Terrigenous Group to mixed fluvial and tidal settings in the Svidol Formation, and to peritidal and shallow-marine conditions in the Opletnya Member of the Mogila Formation. For the first time, the palynostratigraphic data presented here allow for dating the transitional interval and for the precise identification of a major sequence boundary between the Petrohan Terrigenous Group and the Svidol Formation (Iskar Carbonate Group). This boundary most probably corresponds to the major sequence boundary Ol4 occurring in the upper Olenekian of the Tethyan realm and thus enables interregional correlation. The identification of regionally traceable sequence boundaries based on biostratigraphic age control is a first step towards a more accurate stratigraphic correlation and palaeogeographic interpretation of the Early to early Middle Triassic in NW Bulgaria.

Transferability of geodata from European to Canadian (Ontario) sedimentary rocks to study gas transport from nuclear wastes repositories

International Nuclear Information System (INIS)

Fall, M.; Ghafari, H.; Evgin, E.; Nguyen, T.S.

2010-01-01

Document available in extended abstract form only. A deep geological repository (DGR) for low and intermediate level waste in southern Ontario is currently proposed, at a depth of approximately 680 m in an argillaceous limestone formation (Cobourg Limestone) overlain by 200 m of low permeability shale (Ordovician Shale). Significant quantities of gas could be generated in the aforementioned DGR from several processes (e.g., degradation of waste forms, corrosion of waste containers). The accumulation and release of such gases from the repository system may affect a number of processes that influence its long-term safety. Consequently, safety assessments of the proposed DGR need to be supported by a solid understanding of the main mechanisms associated with gas generation and migration and the capability to mathematically model those mechanisms. The development of those mathematical models would usually require the consideration of complex coupled thermo-hydro-mechanical- chemical (THMC) processes. A research program is being conducted in the Department of Civil Engineering of the University of Ottawa in collaboration with the Canadian Nuclear Safety Commission (CNSC) to model the coupled THMC processes associated with gas migration and their impacts on the safety of DGR in southern Ontario. The development and validation of such model as well as the assessment of the impact of gas migration need the acquisition of sufficient amount of (good quality) data on the geomechanical, geochemical, hydraulic, thermal properties of the sedimentary rocks in Southern Ontario as well as relevant gas transport parameters, such as gas entry pressure, Klinkenberg effect, intrinsic permeability, capillary pressure-water saturation relationship. During the past fifteen years, several laboratory and field investigations have been conducted in several countries to acquire geo-data to study and model the THMC processes associated with gas migration in DGR in sedimentary rocks. However

Classification and sedimentary characteristics of lacustrine hyperpycnal channels: Triassic outcrops in the south Ordos Basin, central China

Science.gov (United States)

Xian, Benzhong; Wang, Junhui; Gong, Chenglin; Yin, Yu; Chao, Chuzhi; Liu, Jianping; Zhang, Guodong; Yan, Qi

2018-06-01

Subaquatic channels are known as active conduits for the delivery of terrigenous sediments into related marine and lacustrine basins, as well as important targets for hydrocarbon exploration. Compared to submarine channels, lacustrine subaqueous channels created by hyperpycnal flows are understudied. Using well-exposed outcrops collected from three different locations in the southern Ordos Basin, central China, morphologies and architecture of a channelized hyperpycnal system were studied and classified. Six facies associations represent sedimentary processes from strong erosion by bedload dominated hyperpycnal flows, to transitional deposition jointly controlled by bedload and suspended-load dominated hyperpycnal flows, finally to deposition from suspended-load dominated hyperpycnal flows. On the basis of channel morphologies, infilling sediments and sedimentary processes, the documented channels can be classified into four main categories, which are erosional, bedload dominated, suspended-load dominated, and depositional channels. In very proximal and very distal locations, erosional channels and depositional channels serve as two end-members, while in middle areas, bedload-dominated channels and suspended-load dominated channels are transitional types. Erosional channels, as a response to strong erosion from bedload dominated hyperpycnal flows on upper slope, were mainly filled by mud interbedded with thin sand beds. As flow energy decreases, bedload dominated channels develop on middle slopes, which are characterized mainly by under- to balanced sediment infillings with cross-bedded sandstones and/or minor massive sandstones. Compared to bedload dominated channels, suspended-load dominated channels mainly develop in deeper water, and were filled mainly by massive or planar-laminated sandstones. Depositional channels, as a response to suspended-load dominated hyperpycnal flows in deep-water areas, are characterized by thin-medium bed classical turbidites with

Sedimentary processes in Boca de Quadra and Smeaton Bay: preliminary evidence from excess 210Pb and interstitial-water chemistry

International Nuclear Information System (INIS)

Sugai, S.F.; Burrel, D.C.

1979-01-01

Sedimentary profiles of unsupported 210 Pb (t/sub 1/2/ = 22.26 years) coupled with profiles of redox-sensitive metals in the interstitial water suggest sedimentary processes that have occurred in Boca de Quadra and Smeaton Bay within the past several decades. Although average sedimentation rates can be calculated from excess 210 Pb profiles alone, ancillary information is needed to interpret the history recorded in the sedimentary column. Particularly in dynamic environments such as the fjords examined here, it is necessary to examine the combined effects of: (1) rapid deposition of sediment by slumping or major storms; (2) erosional events such as scouring; (3) homogenization of sediment by storm mixing or bioturbation; and (4) deposition of material from a different source. In this report we discuss efforts underway to examine the events responsible for the observed profiles of excess 210 Pb in the sediment of Boca de Quadra and Smeaton Bay

A note on coarse-grained gravity-flow deposits within proterozoic lacustrine sedimentary rocks, Transvaal sequence, South Africa

Science.gov (United States)

Eriksson, P. G.

A widely developed, thin, coarse-matrix conglomerate occurs within early Proterozoic lacustrine mudrocks in the Transvaal Sequence, South Africa. The poorly sorted tabular chert clasts, alternation of a planar clast fabric with disorientated zones, plus normal and inverse grading in the former rock type suggest deposition by density-modified grain-flow and high density turbidity currents. The lower fan-delta slope palæenvironment inferred for the conglomerate is consistent with the lacustrine interpretation for the enclosing mudrock facies. This intracratonic setting contrasts with the marine environment generally associated with density-modified grain-flow deposits.

Provenance and paleo-weathering of Tertiary accretionary prism-forearc sedimentary deposits of the Andaman Archipelago, India

Science.gov (United States)

Awasthi, Neeraj

2017-12-01

In order to understand the provenance and tectono-sedimentary processes occurring in the Andaman Subduction Zone (ASZ), the Late Cretaceous to Oligocene sedimentary records from the Andaman Islands have been studied. These sedimentary records are considered to have preserved the history of the India-Asia collision, evolution of the Himalayas, climatic development and palaeo-drainage reorganizations on the Indian and Asian plates. About 47 sandstones and mudstones (shales and siltstones) samples were analyzed for whole rock major, trace, and rare earth element compositions. The geochemical results suggest mixing of sediments derived from the mafic igneous sources comprising local ophiolites and volcanic arc of the ASZ and an older Archean to Proterozoic age felsic cratonic source with compositions similar to average granodiorite or upper continental crustal sources. The compositions were dominated by sources of the mafic arc during deposition of the Mithakhari Group, whereas they were controlled by continental sources during deposition of the Andaman Flysch Group. The Hope Town Conglomerate unit of the Mithakhari Group was mainly derived from weathering and erosion of the subaerially exposed local ophiolite thrust sheets, whereas its Namunagarh unit contains significant detritus from volcanic arcs. The Andaman Flysch turbidites were deposited with a greater supply of sediments from first-cycle active continental margin sources probably located in the Tibetan and eastern Myanmar region and recycled quartzose sedimentary sources within the nascent Himalayas. The sediments supplied to both the Mithakhari and the Andaman Flysch Groups were characterized by varying values of CIA, PIA and W. These variable values were either due to non-steady state weathering conditions in the sources or the changing climatic conditions owing to the motion of Indian plate with reference to the equator. The uniformly high CIA and W values in the Andaman Flysch rocks can be related to high

The sedimentary facies characteristics and lithofacies palaeogeography during Middle-Late Cambrian, Sichuan Basin and adjacent area

Directory of Open Access Journals (Sweden)

Feifan Lu

2017-06-01

Full Text Available Combined with the regional strata filling characteristics of Middle-Upper Cambrian, the present paper conducts a systematic research on sedimentary facies in the basin and its peripheral area by utilizing 164 field outcrops and drilling and coring data. Further, the method of “multi-factor comprehensive synthesis based on single-factor analysis” was employed to investigate the sedimentary facies and palaeogeography of the study area and establish the sedimentary facies model. Stratigraphic reveals that the study area represents the pattern of thin-northwest and thick-southeast by stretching northeast-southwest. Within the present basin, the pattern of “one thin and two thick” predominates, while outside the basin “four thin and three thick” filling feature was found. Sedimentary facies shows that the study area was featured by rimmed carbonate platform. Specifically, carbonate platform, slope and northeastern corner Qinling paleooceanic Basin and southeastern corner Jiangnan Bain was identified from the west to the east. The carbonate platform contains restricted platform, evaporation-restricted platform, semi-restricted platform and the platform margin. Single factor analysis and lithofacies palaeogeographic characteristics manifests that during Middle-Late Cambrian, the western Old land evolved into peneplain stage, and that the eastern and southwestern sub-sags remained connected to the open-sea to some extent. At the time, the shllow seawater circulation was relatively restricted, while the ancient seabed tended to be flat and evaporation characteristics significantly diminished. Secondary sea-level fluctuation intensively influenced the development of scaled grain beach. It is suggested that tide marginal beach, intraplatform shoal subfacies zone, along with Shiqian-SangZhi in southeast and Zhenba-Xinshan in northeast platform-margin beach subfacies zone to be preferable targets for the favorable reservoir facies zone and

Application of sequence stratigraphy to carbonate reservoir prediction, Early Palaeozoic eastern Warburton basin, South Australia

Energy Technology Data Exchange (ETDEWEB)

Xiaowen S.; Stuart, W.J.

1996-12-31

The Early Palaeozoic Warburton Basin underlies the gas and oil producing Cooper and Eromanga Basins. Postdepositional tectonism created high potential fracture porosities, complicating the stratigraphy and making reservoir prediction difficult. Sequence stratigraphy integrating core, cuttings, well-log, seismic and biostratigraphic data has recognized a carbonate-dominated to mixed carbonate/siliciclastic supersequence comprising several depositional sequences. Biostratigraphy based on trilobites and conodonts ensures reliable well and seismic correlations across structurally complex areas. Lithofacies interpretation indicates sedimentary environments ranging from carbonate inner shelf, peritidal, shelf edge, deep outer shelf and slope to basin. Log facies show gradually upward shallowing trends or abrupt changes indicating possible sequence boundaries. With essential depositional models and sequence analysis from well data, seismic facies suggest general reflection configurations including parallel-continuous layered patterns indicating uniform neuritic shelf, and mounded structures suggesting carbonate build-ups and pre-existing volcanic relief. Seismic stratigraphy also reveals inclined slope and onlapping margins of a possibly isolated platform geometry. The potential reservoirs are dolomitized carbonates containing oomoldic, vuggy, intercrystalline and fracture porosities in lowstand systems tracts either on carbonate mounds and shelf crests or below shelf edge. The source rock is a deep basinal argillaceous mudstone, and the seal is fine-grained siltstone/shale of the transgressive system tract.

Application of sequence stratigraphy to carbonate reservoir prediction, Early Palaeozoic eastern Warburton basin, South Australia

Energy Technology Data Exchange (ETDEWEB)

Xiaowen S.; Stuart, W.J.

1996-01-01

The Early Palaeozoic Warburton Basin underlies the gas and oil producing Cooper and Eromanga Basins. Postdepositional tectonism created high potential fracture porosities, complicating the stratigraphy and making reservoir prediction difficult. Sequence stratigraphy integrating core, cuttings, well-log, seismic and biostratigraphic data has recognized a carbonate-dominated to mixed carbonate/siliciclastic supersequence comprising several depositional sequences. Biostratigraphy based on trilobites and conodonts ensures reliable well and seismic correlations across structurally complex areas. Lithofacies interpretation indicates sedimentary environments ranging from carbonate inner shelf, peritidal, shelf edge, deep outer shelf and slope to basin. Log facies show gradually upward shallowing trends or abrupt changes indicating possible sequence boundaries. With essential depositional models and sequence analysis from well data, seismic facies suggest general reflection configurations including parallel-continuous layered patterns indicating uniform neuritic shelf, and mounded structures suggesting carbonate build-ups and pre-existing volcanic relief. Seismic stratigraphy also reveals inclined slope and onlapping margins of a possibly isolated platform geometry. The potential reservoirs are dolomitized carbonates containing oomoldic, vuggy, intercrystalline and fracture porosities in lowstand systems tracts either on carbonate mounds and shelf crests or below shelf edge. The source rock is a deep basinal argillaceous mudstone, and the seal is fine-grained siltstone/shale of the transgressive system tract.

Is it possible to use 'twin cores' as a unique sedimentary record? An experimental design based on sediment color

International Nuclear Information System (INIS)

Veiga-Pires, C; Mestre, N C

2009-01-01

Sedimentary cores are widely used for studying Quaternary records. However, the amount of sediment that is available is proportional to the diameter of the core, which is rarely bigger than 15 cm. One way to obtain more sediment is to use two cores retrieved from almost the same location and use them as if they represent a unique sedimentary record. In the present work, an experimental design has been applied to verify if 'twin cores' from an estuary can be considered as representing the same sedimentary record with twice the amount of sediment to study. Because sediment can be characterized based on its color, the variables used as replicates in the experimental design are the three Lab CIE colors acquired with a X-Rite Colortron spectrophotometer. Sediment cores were retrieved from the upper saltmarsh of Gilao River's estuary, southern Portugal. Twin cores, with in between distances of 50 cm, 100 cm and 200 cm, from two different sites were analysed. Results from a nested ANOVA show that even for the closest twin cores (50 cm apart) there is at least one color variable that shows significant variations between the profiles of both cores. These results clearly show that 'twin cores' cannot be used as a unique sedimentary record without any previous testing, at least in such transitional regions.

Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

Energy Technology Data Exchange (ETDEWEB)

Suzette Payne

2006-04-01

This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

Energy Technology Data Exchange (ETDEWEB)

Suzette Payne

2007-08-01

This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

Radioactive sedimentary deposits concerning the coasts of the Camargue

International Nuclear Information System (INIS)

2000-01-01

CRII-RAD has detected abnormal levels of radioactivity on some beaches situated near the Espiguette lighthouse in the south-east coast of France. This document presents the in-situ measurements performed by IPSN. These results confirm a relevant increase of gamma radiation in sedimentary deposits. Chemical analyses have shown that this radioactivity is due to potassium 40 and radionuclides from thorium and uranium series. There is no doubt about the natural origin of this radioactivity but thorough geo-chemical studies are necessary to see whether these radioactive sands are a consequence of nearby industrial activities concerning ore dressing. (A.C.)

Prediction of CO2 leakage during sequestration into marine sedimentary strata

International Nuclear Information System (INIS)

Li, Qi; Wu Zhishen; Li Xiaochun

2009-01-01

Deep ocean storage of CO 2 could help reduce the atmospheric level of greenhouse gas as part of a climate change mitigation strategy. In this paper, a multiphase flow model of CO 2 sequestration into deep ocean sediments was designed associated with the formation of CO 2 hydrates. A simplified assumption was proposed to predict the critical time of CO 2 leakage from marine sedimentary strata into seawater. Moreover, some principal parameters, which include the permeability, anisotropy, total injection amount, and length of the injection part of wellbores, were investigated by numerical simulations. The numerical estimates are used to assess the feasibility and effectiveness of CO 2 storage in deep ocean sediments. Accurately predicting the actual fate of liquid CO 2 sequestered into the marine sedimentary strata at depths greater than 500 m is complicated by uncertainties associated with not only the chemical-physical behavior of CO 2 under such conditions but also the geo-environment of disposal sites. Modeling results have shown some implications that the effectiveness of CO 2 ocean sequestration depends mainly on the injection conditions (such as injection rate, total injection amount, and the depth of injection), the site geology (such as permeability and anisotropy of disposal formations), and the chemical-physical behavior of CO 2 in marine environment

Seismic stratigraphy of Ongole-Paradip continental shelf, east coast of India

Digital Repository Service at National Institute of Oceanography (India)

Murthy, K.S.R.

comprises mainly of three units i) a chaotic facies representing the top surface of an Early Pleistocene sedimentary sequence, ii) a layered sedimentary sequence of parallel to subparallel reflectors (30 to 80 m in thickness), the top surface...

The integration of gravity, magnetic and seismic data in delineating the sedimentary basins of northern Sinai and deducing their structural controls

Science.gov (United States)

Selim, El Sayed Ibrahim

2016-01-01

The Sinai Peninsula is a part of the Sinai sub-plate that located between the southeast Nubian-Arabian shield and the southeastern Mediterranean northward. The main objectives of this investigation are to deduce the main sedimentary basin and its subdivisions, identify the subsurface structural framework that affects the study area and determine the thickness of sedimentary cover of the basement surface. The total intensity magnetic map, Bouguer gravity map and seismic data were used to achieve the study aims. Structural interpretation of the gravity and magnetic data were done by applying advanced processing techniques. These techniques include; Reduce to the pole (RTP), Power spectrum, Tile derivative and Analytical Signal techniques were applied on gravity and magnetic data. Two dimensional gravity and magnetic modeling and interpretation of seismic sections were done to determine the thickness of sedimentary cover of the study area. The integration of our interpretation suggests that, the northern Sinai area consists of elongated troughs that contain many high structural trends. Four major structural trends have been identified, that, reflecting the influence of district regional tectonic movements. These trends are: (1) NE-SW trend; (2) NNW-SSE trend; (3) ENE-WSW trend and (4) WNW-ESE trend. There are also many minor trends, E-W, NW-SE and N-S structural trends. The main sedimentary basin of North Sinai is divided into four sub-basins; (1) Northern Maghara; (2) Northeastern Sinai; (3) Northwestern Sinai and (4) Central Sinai basin. The sedimentary cover ranges between 2 km and 7 km in the northern part of the study area.

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars

Science.gov (United States)

Ewing, R. C.; Lapotre, M. G. A.; Lewis, K. W.; Day, M.; Stein, N.; Rubin, D. M.; Sullivan, R.; Banham, S.; Lamb, M. P.; Bridges, N. T.; Gupta, S.; Fischer, W. W.

2017-12-01

The Mars Science Laboratory rover Curiosity visited two active wind-blown sand dunes within Gale crater, Mars, which provided the first ground-based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial-like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples were present on all dune slopes and had a size and shape similar to their terrestrial counterpart. Grainfall and grainflow occurred on dune and large-ripple lee slopes. Lee slopes were 29° where grainflows were present and 33° where grainfall was present. These slopes are interpreted as the dynamic and static angles of repose, respectively. Grain size measured on an undisturbed impact ripple ranges between 50 μm and 350 μm with an intermediate axis mean size of 113 μm (median: 103 μm). Dissimilar to dune eolian processes on Earth, large, meter-scale ripples were present on all dune slopes. Large ripples had nearly symmetric to strongly asymmetric topographic profiles and heights ranging between 12 cm and 28 cm. The composite observations of the modern sedimentary processes highlight that the Martian eolian rock record is likely different from its terrestrial counterpart because of the large ripples, which are expected to engender a unique scale of cross stratification. More broadly, however, in the Bagnold Dune Field as on Earth, dune-field pattern dynamics and basin-scale boundary conditions will dictate the style and distribution of sedimentary processes.

The Salinas formation in the type-area, Northeastern Minas Gerais: a proposal to review the stratigraphy of the Aracuai belt on sedimentary, metamorphic and U-Pb SHRIMP evidences

International Nuclear Information System (INIS)

Lima, Sirlene A. de Abreu; Pedrosa Soares, Antonio C.; Cordani, Umberto G.; Nutman, Allen

2002-01-01

The Salinas Formation has been considered to be a stratigraphic unit of the Macaubas Group. This group comprises the rift to passive margin sequences of the precursor basin of the Neo proterozoic Aracuai Orogeny, eastern Brazil. However, new road cuts show extensive and spectacular outcrops with very well-preserved sedimentary structures, allowing detailed studies in the type-locality of this formation, located in the Salinas town and surroundings, northeast Minas Gerais State. In its type-locality, the Salinas Formation consists of graywacke, pelite and clast-supported conglomerate, metamorphosed in the green schist facies. The sedimentary lithofacies are grouped into three facies association (shelf, slope and deep-sea), indicating sedimentation from shelf deposits to deep-water turbidites. The shelf sedimentation was influenced by storm-wave during deposition. The slump and deep-sea deposits were generated by gravitational flows and high- to low-concentration turbidity currents. Shelf sandstone, clast-supported conglomerate and proximal to distal turbidites outline a submarine fan system. U-Pb SHRIMP data from detrital zircons of graywacke samples indicate a maximum sedimentation age of ca. 568 Ma. Thus, the Salinas Formation is much younger than the Macaubas Group, and represents late orogenic deposits (ca. 568- 500 Ma). The distal, passive margin unit of the Macaubas Group is now called Ribeirao da Folha Formation (ca. 800 Ma). (author)

Des-A-lupane in an East African lake sedimentary record as a new proxy for the stable carbon isotopic composition of C3 plants

NARCIS (Netherlands)

van Bree, Loes G.J.; Rijpstra, W. Irene C; Al-Dhabi, N.A.; Verschuren, D.; Sinninghe Damste, J.S.; de Leeuw, J.W.

2016-01-01

We studied the high-resolution and well-dated 25,000 year sedimentary record of Lake Challa, a deep tropical crater lake in equatorial East Africa, to explore new proxies for paleoenvironmental and paleohydrological change. Sedimentary biomarker analysis revealed the presence of des-A-triterpenoids

Fifty years of eutrophication and lake restoration reflected in sedimentary carbon and nitrogen isotopes of a small, hardwater lake (south Germany

Directory of Open Access Journals (Sweden)

Emanuel Braig

2013-04-01

Full Text Available This study analyses the response of the carbon and nitrogen isotopic composition of sedimentary organic matter to rapid human-induced eutrophication and meromixis as well as subsequent restoration efforts [in-lake phosphorus (P-Precipitation, P-remediation of the well inflow and multiannual destratification] in a 46-yr sediment core sequence (1963-2009 from Fischkaltersee, a small hard-water lake (S-Germany. In addition, the sediment record was compared with detailed data on water column chemistry during almost (1977-2009 the recorded history of eutrophication and trophic recovery of the named lake. While the onset of eutrophication resulted in an abrupt positive excursion (+2.4‰, the overall reaction of δ13CSOM to ongoing eutrophication and meromixis as well as to permanent hypolimnion aeration and trophic recovery is a continous negative trend (-3.7‰ with the most depleted signatures (-38.8‰ present in the youngest part of the core. This negative trend was not influenced by multiannual hypolimnion aeration, which although oxygenating bottom waters (>2 mg O2 L–1, did not reverse the increasing anoxis in the sediment, as is indicated by an declining Mn/Fe ratio. Hence, we conclude that in Fischkaltersee δ13CSOM was controlled by photoautotrophic input only during an early phase in the eutrophication process. The signal of intensifying microbially mediated carbon cycling processes in the sediment, i.e. methanogenesis and methanotrophy, was superimposed on the primary productivity signal by crossing a certain TP threshold (approx. TP=0.04 mg L–1. Sedimentary δ15N values exhibit an overall increase (+3.4‰ in reaction to the eutrophication process, while trophic recovery produces a continous decrease in the signal (-2.7‰. Linear correlation of δ15N to nitrate utilisation in the epilimnion, however, is rather weak (R2=0.33. Comparison between sediment δ15N values and water column data reveals that two negative shifts in the

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

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Ziliang Liu

Full Text Available A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km. The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

Science.gov (United States)

Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

2015-01-01

A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front" character.

Subsurface temperature maps in French sedimentary basins: new data compilation and interpolation

International Nuclear Information System (INIS)

Bonte, D.; Guillou-Frottier, L.; Garibaldi, C.; Bourgine, B.; Lopez, S.; Bouchot, V.; Garibaldi, C.; Lucazeau, F.

2010-01-01

Assessment of the underground geothermal potential requires the knowledge of deep temperatures (1-5 km). Here, we present new temperature maps obtained from oil boreholes in the French sedimentary basins. Because of their origin, the data need to be corrected, and their local character necessitates spatial interpolation. Previous maps were obtained in the 1970's using empirical corrections and manual interpolation. In this study, we update the number of measurements by using values collected during the last thirty years, correct the temperatures for transient perturbations and carry out statistical analyses before modelling the 3D distribution of temperatures. This dataset provides 977 temperatures corrected for transient perturbations in 593 boreholes located in the French sedimentary basins. An average temperature gradient of 30.6 deg. C/km is obtained for a representative surface temperature of 10 deg. C. When surface temperature is not accounted for, deep measurements are best fitted with a temperature gradient of 25.7 deg. C/km. We perform a geostatistical analysis on a residual temperature dataset (using a drift of 25.7 deg. C/km) to constrain the 3D interpolation kriging procedure with horizontal and vertical models of variograms. The interpolated residual temperatures are added to the country-scale averaged drift in order to get a three dimensional thermal structure of the French sedimentary basins. The 3D thermal block enables us to extract isothermal surfaces and 2D sections (iso-depth maps and iso-longitude cross-sections). A number of anomalies with a limited depth and spatial extension have been identified, from shallow in the Rhine graben and Aquitanian basin, to deep in the Provence basin. Some of these anomalies (Paris basin, Alsace, south of the Provence basin) may be partly related to thick insulating sediments, while for some others (southwestern Aquitanian basin, part of the Provence basin) large-scale fluid circulation may explain superimposed

Hydraulic and sedimentary processes causing anastomosing morphology of the upper Columbia River, British Columbia, Canada

NARCIS (Netherlands)

Makaske, B.; Smith, D.G.; Berendsen, H.J.A.; Boer, de A.G.; Nielen-Kiezebrink, van M.F.; Locking, T.

2009-01-01

The upper Columbia River, British Columbia, Canada, shows typical anastomosing morphology - multiple interconnected channels that enclose floodbasins - and lateral channel stability We analysed field data on hydraulic and sedimentary processes and show that the anastomosing morphology of the upper

Study on epigenetic alterations of ore-enclosing sedimentary rocks

International Nuclear Information System (INIS)

Kondrat'eva, I.A.; Komarova, G.V.

1985-01-01

Epigenetic alterations of sedimentary rocks under effect of exogenous undeground waters of various types: near-surface, ground, stratum, and deep circulation waters, are considered. Association to postsedimentary tectonic structures, confinement of neogenesis to areas of high permeability (porous or crack one), geochemical contradictions between mineral neogenis and facial outlook of deposits, noncoincidence of variability gradient of authigenous mineral associations with variability of primary facial signs of deposits, regular position of mineral formations and ore concentrations in epigenetic mineralogo-geochemical zonation are referred to epigenetic criteria. The complex of epigenetic alterations accompanying mineralization is frequently used as a search sign of uranium deposit of a certain type

Sedimentary thickness and velocity in the northeast boundary of the Parana Basin with Andean earthquakes and local events; Espessura e velocidade das camadas sedimentares na borda nordeste da Bacia do Parana utilizando telessismos da regiao andina e sismos locais

Energy Technology Data Exchange (ETDEWEB)

Silva, Josimar A.; Souza, Luiz M. [Universidade de Sao Paulo (USP), SP (Brazil). Dept. de Geofisica; Assumpcao, Marcelo S. [Universidade de Sao Paulo (USP), SP (Brazil)

2008-07-01

Deep Andean earthquakes are a suitable source of high-frequency P-waves (with good signal to noise ratio up to {approx} 10 Hz) that can be used to obtain high-resolution receiver functions at stations in intra-cratonic basins in Brazil. Receiver functions (Gaussian width 20) at five stations in the Bebedouro seismic area (NE Parana Basin) were calculated using the time domain deconvolution of Ligorria and Ammon (1999). Inter-station Rayleigh wave phase velocities were measured using local earthquakes. Joint inversion of receiver functions and Rayleigh phase velocities provided reasonably well constrained S-wave velocity profiles. Shallow seismic refraction surveys were used to fix the velocities of the surface layers during the inversion. The area is characterized by a thin surface layer of sandstones ({approx}60 m), followed by a {approx}500 m thick basalt layer. Beneath the basalts, low-velocity layers define another sedimentary sequence. These features are consistent with the expected values based on well data at regional distances and confirm the usefulness of high-frequency receiver functions to study sedimentary basins. (author)

Sedimentary Geothermal Feasibility Study: October 2016

Energy Technology Data Exchange (ETDEWEB)

Augustine, Chad [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zerpa, Luis [Colorado School of Mines, Golden, CO (United States)

2017-01-01

The objective of this project is to analyze the feasibility of commercial geothermal projects using numerical reservoir simulation, considering a sedimentary reservoir with low permeability that requires productivity enhancement. A commercial thermal reservoir simulator (STARS, from Computer Modeling Group, CMG) is used in this work for numerical modeling. In the first stage of this project (FY14), a hypothetical numerical reservoir model was developed, and validated against an analytical solution. The following model parameters were considered to obtain an acceptable match between the numerical and analytical solutions: grid block size, time step and reservoir areal dimensions; the latter related to boundary effects on the numerical solution. Systematic model runs showed that insufficient grid sizing generates numerical dispersion that causes the numerical model to underestimate the thermal breakthrough time compared to the analytic model. As grid sizing is decreased, the model results converge on a solution. Likewise, insufficient reservoir model area introduces boundary effects in the numerical solution that cause the model results to differ from the analytical solution.

Sedimentology and sequence stratigraphy of the Lower Jurassic Kayenta Formation, Colorado Plateau, United States

Science.gov (United States)

Sanabria, Diego Ignacio

2001-07-01

Detailed outcrop analysis of the Lower Jurassic Kayenta Formation provides the basis for the formulation of a new sequence stratigraphic model for arid to semi-arid continental deposits and the generation of a comprehensive set of sedimentologic criteria for the recognition of ephemeral stream deposits. Criteria for the recognition of ephemeral deposits in the ancient record were divided into three categories according to the scale of the feature being considered. The first category takes into account sedimentary structures commonly found in the record of ephemeral stream deposits including hyperconcentrated and debris flow deposits, planar parallel bedding, sigmoidal cross-bedding, hummocky cross-bedding, climbing ripple lamination, scour-and-fill structures, convolute bedding, overturned cross-bedding, ball-and-pillow structures, pocket structures, pillars, mud curls, flaser lamination, algal lamination, termite nests, and vertebrate tracks. The second category is concerned with the mesoscale facies architecture of ephemeral stream deposits and includes waning flow successions, bedform climb, downstream accretion, terminal wadi splays, and channel-fill successions indicating catastrophic flooding. At the large-scale facies architecture level, the third category, ephemeral stream deposits are commonly arranged in depositional units characterized by a downstream decrease in grain size and scale of sedimentary structures resulting from deposition in terminal fan systems. Outcrops of the Kayenta Formation and its transition to the Navajo Sandstone along the Vermilion and Echo Cliffs of Northern Arizona indicate that wet/dry climatic cyclicity exerted a major control on regional facies architecture. Two scales of wet/dry climatic cyclicity can be recognized in northern Arizona. Three sequence sets composed of rocks accumulated under predominantly dry or wet conditions are the expression of long-term climatic cyclicity. Short-term climatic cyclicity, on the other hand

Depositional environments and sequence stratigraphy of the Bahram Formation (middle–late Devonian in north of Kerman, south-central Iran

Directory of Open Access Journals (Sweden)

Afshin Hashmie

2016-09-01

Full Text Available This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation (middle–late Devonian in south-central Iran are based on two measured stratigraphic sections in the southern Tabas block. The Bahram Formation overlies red sandstones Padeha Formation in sections Hutk and Sardar and is overlain by Carboniferous carbonate deposits of Hutk Formation paraconformably, with a thickness of 354 and 386 m respectively. Mixed siliciclastic and carbonate sediments are present in this succession. The field observations and laboratory studies were used to identify 14 micro/petrofacies, which can be grouped into 5 depositional environments: shore, tidal flat, lagoon, shoal and shallow open marine. A mixed carbonate-detrital shallow shelf is suggested for the depositional environment of the Bahram Formation which deepens to the east (Sardar section and thins in southern locations (Hutk section. Three 3rd-order cyclic siliciclastic and carbonate sequences in the Bahram Formation and one sequence shared with the overlying joint with Hutk Formation are identified, on the basis of shallowing upward patterns in the micro/pertofacies.

Interactions between sedimentary evolution and prehistoric human occupation in the south-central coast of Santa Catarina, Brazil

Directory of Open Access Journals (Sweden)

Paulo César Fonseca Giannini

2010-04-01

Full Text Available Since the beginning of the human occupation in the south-central coast of Santa Catarina State, in Brazil, the articulation between natural and anthropic processes modeled a strongly domesticated landscape, shaped by the massive construction of shell mounds of monumental dimensions and millenarian permanence. In the coastal plain between Passagem da Barra (Laguna District and Figueirinha Lake (Jaguaruna District, 76 sambaquis were mapped, 48 of which have been dated. Systematic site surveys and radiocarbon datings allowed identifying patterns of spatial distribution in sambaquis according to the sedimentary context at the time of construction, stratigraphy and age. Based on these criteria, the following groups were recognized: five geological-geomorphological contexts of location; three stratigraphic patterns; and four phases of sambaqui occupation in the area, based on site number and type of constructive pattern. The model for sedimentary evolution and time-space distribution of sambaquis shows that sites were built in already emerged areas and that inland sites, away from the lagoons, may have not be preserved or they are not exposed due to the continuous sedimentary filling that characterized this region after the maximum Holocene transgression. The crossing of data, here proposed, shows the importance of integral approaches between archaeology and geosciences for the study of landscape evolution.

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars.

Science.gov (United States)

Ewing, R C; Lapotre, M G A; Lewis, K W; Day, M; Stein, N; Rubin, D M; Sullivan, R; Banham, S; Lamb, M P; Bridges, N T; Gupta, S; Fischer, W W

2017-12-01

The Mars Science Laboratory rover Curiosity visited two active wind-blown sand dunes within Gale crater, Mars, which provided the first ground-based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial-like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples were present on all dune slopes and had a size and shape similar to their terrestrial counterpart. Grainfall and grainflow occurred on dune and large-ripple lee slopes. Lee slopes were ~29° where grainflows were present and ~33° where grainfall was present. These slopes are interpreted as the dynamic and static angles of repose, respectively. Grain size measured on an undisturbed impact ripple ranges between 50 μm and 350 μm with an intermediate axis mean size of 113 μm (median: 103 μm). Dissimilar to dune eolian processes on Earth, large, meter-scale ripples were present on all dune slopes. Large ripples had nearly symmetric to strongly asymmetric topographic profiles and heights ranging between 12 cm and 28 cm. The composite observations of the modern sedimentary processes highlight that the Martian eolian rock record is likely different from its terrestrial counterpart because of the large ripples, which are expected to engender a unique scale of cross stratification. More broadly, however, in the Bagnold Dune Field as on Earth, dune-field pattern dynamics and basin-scale boundary conditions will dictate the style and distribution of sedimentary processes.

Sedimentary features and exploration targets of Middle Permian reservoirs in the SW Sichuan Basin

Directory of Open Access Journals (Sweden)

Guoming Xu

2015-11-01

Full Text Available The exploration direction and targets for the large-scale Middle Permian gas reservoirs in the Sichuan Basin are hot spots and challenges in current exploration researches. The exploration successes of large gas field of Cambrian Longwangmiao Formation in Gaoshiti-Moxi region, Central Sichuan Basin, indicated that prospective sedimentary facies belt was the basis for the formation of large gas fields. In this paper, based on seismic data, outcrop data and drilling data, the tectonic framework and sedimentary features of the Middle Permian in the SW Sichuan Basin were comprehensively studied. The following conclusions were reached from the perspective of sedimentary facies control: (1 during the Middle Permian, this region was in shallow water gentle slope belts with high energy, where thick reef flat facies were deposited; (2 the basement was uplifted during Middle Permian, resulting in the unconformity weathering crust at the top of Maokou Formation due to erosion; the SW Sichuan Basin was located in the karst slope belt, where epigenic karstification was intense; and (3 reef flat deposits superimposed by karst weathering crust was favorable for the formation of large-scale reef flat karst reservoirs. Based on the combination of the resources conditions and hydrocarbon accumulation conditions in this region, it was pointed out that the Middle Permian has great potential of large-scale reef flat karst gas reservoir due to its advantageous geological conditions; the Middle Permian traps with good hydrocarbon accumulation conditions were developed in the Longmen Mountain front closed structural belt in the SW Sichuan Basin and Western Sichuan Basin depression slope belt, which are favorable targets for large-scale reef flat karst reservoirs.

Types of tectonic structures, sedimentary volcanogenetic formations of a mantle, favourable processes for exogenetic and polygenetic uranium deposits formation

International Nuclear Information System (INIS)

Danchev, V.I.; Komarnitskij, G.M.; Levin, V.N.; Shumlyanskij, V.A.

1985-01-01

Factors, affecting mineralization processes are considered. Characteristic features of uranium-bearing provinces are as follows: the presence of crust of continental type; deep-seated tectonic structures-rises and saggings, roofs, gneiss domes, rift zones and transform fractures; specialization for uranium of sedimentary and magmatic formations; the presence of manifestation regions of deep thermal and gaseous flow, etc. In uranium-bearing provinces territories favourable for the manifestation of different types of uranium mineralization: metamorphogenetic, polygenetic and exogenetic ones, are singled out. Different epochs of uranium ore formation are established. In sedimentary masses tectonic regime and climate are of special importance, and for epigenetic deposits, formed with an aid of underground waters-hydrogeological conditions. In the limits of the main structural elements of the Earth crust and geotectonic structures of higher orders the following types of sedimentary and volcanic formations can be singled out: 1-formations with exogenous uranium mineralization; 2-formations, accumulated in the epochs of epigenous ore formation; 3-formations fav ourable for epigenous uranium deposit formation; 4-formations unfavourable for the formation and localization of uranium mineralization

Cenozoic uplift of the Tibetan Plateau: Evidence from the tectonic–sedimentary evolution of the western Qaidam Basin

Directory of Open Access Journals (Sweden)

Yadong Wang

2012-03-01

Full Text Available Geologists agree that the collision of the Indian and Asian plates caused uplift of the Tibet Plateau. However, controversy still exists regarding the modes and mechanisms of the Tibetan Plateau uplift. Geology has recorded this uplift well in the Qaidam Basin. This paper analyzes the tectonic and sedimentary evolution of the western Qaidam Basin using sub-surface seismic and drill data. The Cenozoic intensity and history of deformation in the Qaidam Basin have been reconstructed based on the tectonic developments, faults growth index, sedimentary facies variations, and the migration of the depositional depressions. The changes in the sedimentary facies show that lakes in the western Qaidam Basin had gone from inflow to still water deposition to withdrawal. Tectonic movements controlled deposition in various depressions, and the depressions gradually shifted southeastward. In addition, the morphology of the surface structures in the western Qaidam Basin shows that the Cenozoic tectonic movements controlled the evolution of the Basin and divided it into (a the southern fault terrace zone, (b a central Yingxiongling orogenic belt, and (c the northern fold-thrust belt; divided by the XI fault (Youshi fault and Youbei fault, respectively. The field data indicate that the western Qaidam Basin formed in a Cenozoic compressive tectonic environment caused by the India–Asia plate collision. Further, the Basin experienced two phases of intensive tectonic deformation. The first phase occurred during the Middle Eocene–Early Miocene (Xia Ganchaigou Fm. and Shang Ganchaigou Fm., 43.8–22 Ma, and peaked in the Early Oligocene (Upper Xia Ganchaigou Fm., 31.5 Ma. The second phase occurred between the Middle Miocene and the Present (Shang Youshashan Fm. and Qigequan Fm., 14.9–0 Ma, and was stronger than the first phase. The tectonic–sedimentary evolution and the orientation of surface structures in the western Qaidam Basin resulted from the Tibetan

Narrative depositional systems on the area with Nalinggou the relationship between uranium mineralization

International Nuclear Information System (INIS)

Meng Rui

2012-01-01

For sandstone-type uranium deposits in China began to research the late 1950s, 1990s in-situ leachable sand stone-type uranium deposits has become China's industrial significance of the important uranium deposits type. The sedimentary system analysis in in-situ leachable sandstone-type uranium deposit research plays a very important role. Based on the sedimentary system analysis and sequence stratigraphy as the basis, the area of Nalinggou on ridge middle Jurassic straight ROM group sedimentary system characteristics, middle Jurassic straight ROM group of sand body thickness, the area on ridge aspects of river channel exhibition cloth direction studied that: (1) river space distribution direction control the sand body cloth of the spatial distribution, then affects fu cloth of the spatial distribution of uranium sand body; (2) the evolution of the sedimentary environment created a good sand sequence distribution and enrichment conditions intercalation, be helpful for interlayer oxidation effect; (3) sequence of sedimentary control three layer structure lithology space combination. (authors)

Completed Ensemble Empirical Mode Decomposition: a Robust Signal Processing Tool to Identify Sequence Strata

Science.gov (United States)

Purba, H.; Musu, J. T.; Diria, S. A.; Permono, W.; Sadjati, O.; Sopandi, I.; Ruzi, F.

2018-03-01

Well logging data provide many geological information and its trends resemble nonlinear or non-stationary signals. As long well log data recorded, there will be external factors can interfere or influence its signal resolution. A sensitive signal analysis is required to improve the accuracy of logging interpretation which it becomes an important thing to determine sequence stratigraphy. Complete Ensemble Empirical Mode Decomposition (CEEMD) is one of nonlinear and non-stationary signal analysis method which decomposes complex signal into a series of intrinsic mode function (IMF). Gamma Ray and Spontaneous Potential well log parameters decomposed into IMF-1 up to IMF-10 and each of its combination and correlation makes physical meaning identification. It identifies the stratigraphy and cycle sequence and provides an effective signal treatment method for sequence interface. This method was applied to BRK- 30 and BRK-13 well logging data. The result shows that the combination of IMF-5, IMF-6, and IMF-7 pattern represent short-term and middle-term while IMF-9 and IMF-10 represent the long-term sedimentation which describe distal front and delta front facies, and inter-distributary mouth bar facies, respectively. Thus, CEEMD clearly can determine the different sedimentary layer interface and better identification of the cycle of stratigraphic base level.

Mineralogical correlation of surficial sediment from area drainages with selected sedimentary interbeds at the Idaho National Engineering Laboratory, Idaho

Energy Technology Data Exchange (ETDEWEB)

Bartholomay, R.C.

1990-08-01

Ongoing research by the US Geological Survey at the INEL involves investigation of the migration of radioactive elements contained in low-level radioactive waste, hydrologic and geologic factors affecting waste movement, and geochemical factors that influence the chemical composition of the waste. Identification of the mineralogy of the Snake River Plain is needed to aid in the study of the hydrology and geochemistry of subsurface waste disposal. The US Geological Surveys project office at the Idaho National Engineering Laboratory, in cooperation with the US Department of Energy, used mineralogical data to correlate surficial sediment samples from the Big Lost River, Little Lost River, and Birch Greek drainages with selected sedimentary interbed core samples taken from test holes at the RWMC (Radioactive Waste Management Complex), TRA (Test Reactors Area), ICPP (Idaho Chemical Processing Plant), and TAN (Test Area North). Correlating the mineralogy of a particular present-day drainage area with a particular sedimentary interbed provides information on historical source of sediment for interbeds in and near the INEL. Mineralogical data indicate that surficial sediment samples from the Big Lost River drainage contained a larger amount of feldspar and pyroxene and a smaller amount of calcite and dolomite than samples from the Little Lost River and Birch Creek drainages. Mineralogical data from sedimentary interbeds at the RWMC, TRA, and ICPP correlate with surficial sediment of the present-day big Lost River drainage. Mineralogical data from a sedimentary interbed at TAN correlate with surficial sediment of the present-day Birch Creek drainage. 13 refs., 5 figs., 3 tabs.

Mineralogical correlation of surficial sediment from area drainages with selected sedimentary interbeds at the Idaho National Engineering Laboratory, Idaho

International Nuclear Information System (INIS)

Bartholomay, R.C.

1990-08-01

Ongoing research by the US Geological Survey at the INEL involves investigation of the migration of radioactive elements contained in low-level radioactive waste, hydrologic and geologic factors affecting waste movement, and geochemical factors that influence the chemical composition of the waste. Identification of the mineralogy of the Snake River Plain is needed to aid in the study of the hydrology and geochemistry of subsurface waste disposal. The US Geological Surveys project office at the Idaho National Engineering Laboratory, in cooperation with the US Department of Energy, used mineralogical data to correlate surficial sediment samples from the Big Lost River, Little Lost River, and Birch Greek drainages with selected sedimentary interbed core samples taken from test holes at the RWMC (Radioactive Waste Management Complex), TRA (Test Reactors Area), ICPP (Idaho Chemical Processing Plant), and TAN (Test Area North). Correlating the mineralogy of a particular present-day drainage area with a particular sedimentary interbed provides information on historical source of sediment for interbeds in and near the INEL. Mineralogical data indicate that surficial sediment samples from the Big Lost River drainage contained a larger amount of feldspar and pyroxene and a smaller amount of calcite and dolomite than samples from the Little Lost River and Birch Creek drainages. Mineralogical data from sedimentary interbeds at the RWMC, TRA, and ICPP correlate with surficial sediment of the present-day big Lost River drainage. Mineralogical data from a sedimentary interbed at TAN correlate with surficial sediment of the present-day Birch Creek drainage. 13 refs., 5 figs., 3 tabs

Major element compositions of fluid inclusions from hydrothermal vein-type deposits record eroded sedimentary units in the Schwarzwald district, SW Germany

Science.gov (United States)

Walter, Benjamin F.; Burisch, Mathias; Marks, Michael A. W.; Markl, Gregor

2017-12-01

Mixing of sedimentary formation fluids with basement-derived brines is an important mechanism for the formation of hydrothermal veins. We focus on the sources of the sediment-derived fluid component in ore-forming processes and present a comprehensive fluid inclusion study on 84 Jurassic hydrothermal veins from the Schwarzwald mining district (SW Germany). Our data derive from about 2300 fluid inclusions and reveal differences in the average fluid composition between the northern, central, and southern Schwarzwald. Fluids from the northern and southern Schwarzwald are characterised by high salinities (18-26 wt% NaCl+CaCl2), low Ca/(Ca+Na) mole ratios (0.1-0.4), and variable Cl/Br mass ratios (30-1140). In contrast, fluids from the central Schwarzwald show even higher salinities (23-27 wt% NaCl+CaCl2), higher Ca/(Ca+Na) mole ratios (0.2-0.9), and less variable Cl/Br mass ratios (40-130). These fluid compositions correlate with the nature and thickness of the now eroded sedimentary cover rocks. Compared to the northern and the southern Schwarzwald, where halite precipitation occurred during the Middle Triassic, the sedimentary basin in the central Schwarzwald was relatively shallow at this time and no halite was precipitated. Accordingly, Cl/Br ratios of fluids from the central Schwarzwald provide no evidence for the reaction of a sedimentary brine with halite, whereas those from the northern and southern Schwarzwald do. Instead, elevated Ca/(Ca+Na), high SO4 contents, and relatively low Cl/Br imply the presence of a gypsum dissolution brine during vein formation in the central Schwarzwald which agrees with the reconstructed regional Triassic geology. Hence, the information archived in fluid inclusions from hydrothermal veins in the crystalline basement has the potential for reconstructing sedimentary rocks in the former overburden.

Application of the authigenic 10Be/9Be dating method to Late Miocene-Pliocene sequences in the northern Danube Basin (Pannonian Basin System): Confirmation of heterochronous evolution of sedimentary environments

Science.gov (United States)

Šujan, Michal; Braucher, Régis; Kováč, Michal; Bourlès, Didier L.; Rybár, Samuel; Guillou, Valéry; Hudáčková, Natália

2016-02-01

Authigenic 10Be/9Be dating method was applied to lacustrine, deltaic and alluvial sequences of the northern Danube Basin (Pannonian Basin System), to bridge the insufficiency of geochronological data for the Late Miocene to Pliocene period. The measurements of 51 samples (both lacustrine and floodplain), ranging from 11.6 to 0.95 Ma are consistent with the existing magnetostratigraphic and biostratigraphic data standing mainly on the evolution degree of endemic mollusk fauna, mammals and dinocysts. This agreement confirms our assumption that the incoming beryllium fluxes remained constant over the studied time period and thus that the two initial 10Be/9Be ratios determined in actual Holocene/Late Pleistocene sediments (lacustrine and floodplain) are valid for these environments. The obtained ages indicate gradual progradation of the deltaic depositional systems across the Danube Basin with a clear time-transgressional character, replacing basin floor and shelfal environments. Deltaic sedimentation occurred firstly in the north at foothills of the Western Carpathians from 11.0 Ma, and changed to the alluvial environment after 10.5 Ma. At the same time (~ 10.5 Ma), the paleo-Danube deltaic system draining the Eastern Alps entered the study area from the Vienna Basin situated on the West. Later, the deltaic systems were merged in the central part of the basin and reached its southeastern margin at ~ 9.4 Ma. Regression of the Lake Pannon from the southernmost part of the study area is evidenced after 8.7 Ma. Alluvial deposition of meandering rivers lasting until 6.0-5.0 Ma followed and was interrupted by the early Pliocene basin inversion. Sedimentation of braided streams took place during the late Pliocene and Pleistocene, reflecting uplift of mountains surrounding the basin margins. This study documents the powerful potential of the authigenic 10Be/9Be dating method and its reliability in a basin with complicated tectonic and sedimentary history. It demonstrates that

Seeking Signs of Life on Mars: The Importance of Sedimentary Suites as Part of Mars Sample Return

Science.gov (United States)

iMOST Team; Mangold, N.; McLennan, S. M.; Czaja, A. D.; Ori, G. G.; Tosca, N. J.; Altieri, F.; Amelin, Y.; Ammannito, E.; Anand, M.; Beaty, D. W.; Benning, L. G.; Bishop, J. L.; Borg, L. E.; Boucher, D.; Brucato, J. R.; Busemann, H.; Campbell, K. A.; Carrier, B. L.; Debaille, V.; Des Marais, D. J.; Dixon, M.; Ehlmann, B. L.; Farmer, J. D.; Fernandez-Remolar, D. C.; Fogarty, J.; Glavin, D. P.; Goreva, Y. S.; Grady, M. M.; Hallis, L. J.; Harrington, A. D.; Hausrath, E. M.; Herd, C. D. K.; Horgan, B.; Humayun, M.; Kleine, T.; Kleinhenz, J.; Mackelprang, R.; Mayhew, L. E.; McCubbin, F. M.; McCoy, J. T.; McSween, H. Y.; Moser, D. E.; Moynier, F.; Mustard, J. F.; Niles, P. B.; Raulin, F.; Rettberg, P.; Rucker, M. A.; Schmitz, N.; Sefton-Nash, E.; Sephton, M. A.; Shaheen, R.; Shuster, D. L.; Siljestrom, S.; Smith, C. L.; Spry, J. A.; Steele, A.; Swindle, T. D.; ten Kate, I. L.; Usui, T.; Van Kranendonk, M. J.; Wadhwa, M.; Weiss, B. P.; Werner, S. C.; Westall, F.; Wheeler, R. M.; Zipfel, J.; Zorzano, M. P.

2018-04-01

Sedimentary, and especially lacustrine, depositional environments are high-priority geological/astrobiological settings for Mars Sample Return. We review the detailed investigations, measurements, and sample types required to evaluate such settings.

Groundwater Recharge Process in the Morondava Sedimentary Basin, Southwestern Madagascar

International Nuclear Information System (INIS)

Mamifarananahary, E.; Rajaobelison, J.; Ramaroson, V.; Rahobisoa, J.J.

2007-01-01

The groundwater recharge process in the Morondava Sedimentary basin was determined using chemical and isotopic tools. The results showed that the main recharge into shallow aquifer is from infiltration of evaporated water. Into deeper aquifer, it is done either from direct infiltration of rainfall from recharge areas on the top of the hill in the East towards the low-lying discharge areas in the West, or from vertical infiltration of evaporated shallow groundwater. The tritium contents suggest that recharge from shallow aquifers is from recent rainfall with short residence time while recharge into deeper aquifers is from older rainfall with longer residence time.

Stratigraphy, tectonic and ore potential of pre-cambrian unities from Serro region-MG (Mato Grosso quadrangle)

International Nuclear Information System (INIS)

Assis, L.C. de.

1982-01-01

Geological and stratigraphic elements of the Proterozoic units of the Serro region, Mato Grosso Quadrangle, show the absence of the faciological transition between the Espinhaco Group and the Minas Supergroup. Occurs in this region is a lithostratigraphical sequence of four distinct units: the Crystalline Basement; the Volcano-Sedimentary Sequence of Serro; the Minas Supergroup. The ore potential of the region includes: quartz veins, within the Galho do Miguel Formation; diamond, within the Sopa conglomerates; gold, in alluvial deposits and remobilized in quartz veins of the Sopa-Brumadinho Formation; bauxite, in the metabasics; uranium in the metaconglomerates of Moeda Formation; iron, in Caue Formation; chromium, gold and base metals in the Volcano-Sedimentary Sequence of Serro. Emphasis is given to the characterization of the Volcano-Sedimentary Sequence of Serro and its mineralization that is characterized as a stratiform massif with important volcano-sedimentary contribution, possible, a greenstone belt, with high gold-bearing potential. (author)

Hydrogeologic framework of fractured sedimentary rock, Newark Basin, New Jersey

Science.gov (United States)

Lacombe, Pierre J.; Burton, William C.

2010-01-01

The hydrogeologic framework of fractured sedimentary bedrock at the former Naval Air Warfare Center (NAWC), Trenton, New Jersey, a trichloroethylene (TCE)-contaminated site in the Newark Basin, is developed using an understanding of the geologic history of the strata, gamma-ray logs, and rock cores. NAWC is the newest field research site established as part of the U.S. Geological Survey Toxic Substances Hydrology Program, Department of Defense (DoD) Strategic Environmental Research and Development Program, and DoD Environmental Security Technology Certification Program to investigate contaminant remediation in fractured rock. Sedimentary bedrock at the NAWC research site comprises the Skunk Hollow, Byram, and Ewing Creek Members of the Lockatong Formation and Raven Rock Member of the Stockton Formation. Muds of the Lockatong Formation that were deposited in Van Houten cycles during the Triassic have lithified to form the bedrock that is typical of much of the Newark Basin. Four lithotypes formed from the sediments include black, carbon-rich laminated mudstone, dark-gray laminated mudstone, light-gray massive mudstone, and red massive mudstone. Diagenesis, tectonic compression, off-loading, and weathering have altered the rocks to give some strata greater hydraulic conductivity than other strata. Each stratum in the Lockatong Formation is 0.3 to 8 m thick, strikes N65 degrees E, and dips 25 degrees to 70 degrees NW. The black, carbon-rich laminated mudstone tends to fracture easily, has a relatively high hydraulic conductivity and is associated with high natural gamma-ray count rates. The dark-gray laminated mudstone is less fractured and has a lower hydraulic conductivity than the black carbon-rich laminated mudstone. The light-gray and the red massive mudstones are highly indurated and tend to have the least fractures and a low hydraulic conductivity. The differences in gamma-ray count rates for different mudstones allow gamma-ray logs to be used to correlate and

Physicomechanical parameters of sedimentary rocks in eastern Sichuan, China

International Nuclear Information System (INIS)

Guo, Jian; Sun, Yan; Shu, Liangshu; Zhu, Wenbin; Wang, Feng; Li, Benliang; Liu, Deliang

2009-01-01

Rock samples were collected and selected from the sedimentary covering strata from Cambrian to Jurassic in eastern Sichuan, China, which belongs to the Upper Yangtze plate. Physicomechanical parameters were measured systematically. Based on parametric texture characteristics and observation data of geology, five regional layer-slip systems are derived. The five layer-slip systems correspond to five reservoir–cover systems, as the incompetent beds correspond to cover beds and the competent beds to reservoir beds. In comparison with the Middle and Lower Yangtze plates, the physicomechanical parameters, lithologic composition and structural characteristics are basically similar to the Upper Yangtze plate. This comparison offers some insight into the oil and gas reservoir–cover systems in the region

Stability of IRSL signals from sedimentary K-feldspar samples

DEFF Research Database (Denmark)

Thomsen, Kristina Jørkov; Murray, A.S.; Jain, Mayank

2011-01-01

for potassium-rich sedimentary feldspars. We show that the natural post-IR IRSL (pIRIR) signal from a 3.6 Ma old sample is in apparent saturation on a laboratory generated dose response curve, i.e. it does not show detectable fading in nature although a low fading rate is observed on laboratory time scales. We...... be explained in terms of either a single- or multiple-trap model. We present evidence that may suggest that at least part of pIRIR signal is derived from a high temperature trap (∼550°C thermoluminescence (TL) peak), although again the data can also be explained in terms of a single-trap model. Finally, we...

Genetic data from algae sedimentary DNA reflect the influence of environment over geography.

Science.gov (United States)

Stoof-Leichsenring, Kathleen R; Herzschuh, Ulrike; Pestryakova, Luidmila A; Klemm, Juliane; Epp, Laura S; Tiedemann, Ralph

2015-08-11

Genetic investigations on eukaryotic plankton confirmed the existence of modern biogeographic patterns, but analyses of palaeoecological data exploring the temporal variability of these patterns have rarely been presented. Ancient sedimentary DNA proved suitable for investigations of past assemblage turnover in the course of environmental change, but genetic relatedness of the identified lineages has not yet been undertaken. Here, we investigate the relatedness of diatom lineages in Siberian lakes along environmental gradients (i.e. across treeline transects), over geographic distance and through time (i.e. the last 7000 years) using modern and ancient sedimentary DNA. Our results indicate that closely-related Staurosira lineages occur in similar environments and less-related lineages in dissimilar environments, in our case different vegetation and co-varying climatic and limnic variables across treeline transects. Thus our study reveals that environmental conditions rather than geographic distance is reflected by diatom-relatedness patterns in space and time. We tentatively speculate that the detected relatedness pattern in Staurosira across the treeline could be a result of adaptation to diverse environmental conditions across the arctic boreal treeline, however, a geographically-driven divergence and subsequent repopulation of ecologically different habitats might also be a potential explanation for the observed pattern.

The Rajang Unconformity: Major provenance change between the Eocene and Miocene sequences in NW Borneo

Science.gov (United States)

Breitfeld, H. T.; Hennig, J.; BouDagher-Fadel, M.; Hall, R.

2017-12-01

The offshore Sarawak Basin NW of North Sarawak is a major hydrocarbon province in SE Asia. A very thick sedimentary sequence of Oligocene to ?Early Miocene age, named Cycle 1, is an important hydrocarbon source and reservoir. Despite numerous wells the stratigraphy and tectonic history is not very well understood. The Nyalau Formation of onshore North Sarawak is the supposed equivalent of the offshore Cycle 1 sequence. The Nyalau Formation is a thick sedimentary sequence of mainly tidal to deltaic deposits. The formation is dominated by well-bedded sandstone-mudstone alternations and thicker sandstones with abundant bioturbation. The sandstones are predominantly arenaceous. Various lithic fragments and feldspar indicate multiple sources and fresh input from igneous and metamorphic rocks. Interbedded thin limestone beds and marls yielded Early Miocene foraminifera for the upper part of the succession. Zircons separated from the sandstones yielded mainly Cretaceous and Triassic ages. The Triassic is the dominant age population. The Nyalau Formation conformably overlies the Buan Shale and the Tatau Formation, and in places unconformably overlies the Belaga Formation. The Belaga Formation is part of the Rajang Group that represents remnants of a large submarine fan deposited in the Late Cretaceous to Eocene in Central Sarawak. In contrast to the Nyalau Formation, the majority of zircons from the Rajang Group have Cretaceous ages. This marks an important change in provenance at the major unconformity separating the Belaga and Nyalau Formations. This unconformity was previously interpreted as the result of an orogeny in the Late Eocene. However, there is no evidence for a subduction or collision event at this time in Sarawak. We interpret it to mark plate reorganisation in the Middle Eocene and name it the Rajang Unconformity. Borneo is the principal source of Cretaceous zircons which were derived from the Schwaner Mountains and West Sarawak. The dominant Triassic zircon

Evidence for the preservation of technogenic tritiated organic compounds in an estuarine sedimentary environment.

Science.gov (United States)

Croudace, Ian W; Warwick, Phillip E; Morris, Jenny E

2012-06-05

The macrotidal Severn Estuary (southwestern UK) has received a broad range of industrial discharges since the beginning of the Industrial Revolution. A more recent anthropogenic input to the estuary has been technogenic tritium (specifically organically bound tritium, OBT). This was derived from a specialized industrial laboratory producing custom radiolabeled compounds for life science research and diagnostic testing from 1980 until 2008. While it was generally acknowledged that the radiological impact of the tritium discharges into the Estuary was small, public concern motivated the company and regulatory agencies to commission several research studies from 1998 to 2005 to better understand their environmental impact. This study examined OBT interaction with estuarine sediment by acquiring a broad range of geochemical and sedimentological data from a suite of sediment cores collected from the northern side of the Estuary. Two important observations are that the OBT compounds are strongly bound to the clay/silt fraction of sediment and that the down-core OBT profiles in intertidal and subtidal sediments are broadly similar to the discharge record. Geochemical and chronometric methods (Cu, Pb and Zn elemental profiles, (210)Pb, (137)Cs) provide important corroboration of the OBT record. A key additional piece of evidence that firmly authenticated the established chronology was the discovery of a previously unreported sedimentary marker layer that was generated by a major storm surge that occurred on December 13, 1981. Although this study has provided clear evidence of systematic accumulation of OBT in sedimentary sinks of the region, an estimation of its depositional inventory shows it represents only a small fraction of the total discharge. This modest retention in the principal sedimentary sinks of the Severn Estuary system reflects the particular dynamics of this highly macrotidal sediment starved estuary.

Field investigation with regard to the impermeability of clay formations. Helium-4 soil gas surveys in sedimentary basins as a tentative study of secondary permeability in clayey sequences

International Nuclear Information System (INIS)

Lombardi, S.; Benvegnu, F.; Brondi, A.; Polizzano, C.

1993-01-01

This report deals with a tentative study for the detection of the secondary permeability in clayey formations conducted in several sedimentary basins in Central Italy, by means of geochemical methods. The main purposes are: to try a geochemical method, based on the distribution of deep origin gases in soil gas ( 4 He and 222 Rn), to detect buried fault systems and to study the permeability of clay as a potential migration pathway for nuclides of radioactive waste deposits; to verify the effectiveness of this method for the selection of suitable sites for radwaste disposal. This research programme consists in a collaboration between ENEA and the University of Rome within the communitarian programme for the disposal of high level and long-live radwaste. Investigations concerned sedimentary basins filled by sand-clay formations 1000-2000 meters thick and characterized by different tectonic: Era and Chiani-Paglia Valleys (Tuscany and North Latium), structural trenches due to extensive tectonics along the tyrrhenian edge, and Vasto region, a basin in the 'Adriatic foretrench', characterized by compressive tectonics. The investigated areas are near or directly correspond to geothermal fields or to hydrocarbon reservoirs supplying gases which may migrate upward along fractures. Almost 4000 soil gas samples were collected in the three surveyed areas; the sampling density was of about 1.5 points / km 2 , normally used in the regional scale surveys. The obtained results show that the observed helium anomalies are distributed or elongated according to the main tectonic features of the substratum (fault systems, fractures, deep structures); the magnitude of anomalies seems to correlate with the nature of the deep gas reservoir (i.e. oil in Vasto), geothermal reservoir in the Paglia valley. These observations seem to confirm that the presence of deep origin gases in soils is controlled by tectonics. Clay thickness does not significantly control the uprising of deep gases: in

Highly Shocked Low Density Sedimentary Rocks from the Haughton Impact Structure, Devon Island, Nunavut, Canada

Science.gov (United States)

Osinski, G. R.; Spray, J. G.

2001-01-01

We present the preliminary results of a detailed investigation of the shock effects in highly shocked, low density sedimentary rocks from the Haughton impact structure. We suggest that some textural features can be explained by carbonate-silicate immiscibility. Additional information is contained in the original extended abstract.

Thermal conductivity of sedimentary rocks - selected methodological, mineralogical and textural studies

Energy Technology Data Exchange (ETDEWEB)

Midttoemme, Kirsti

1997-12-31

The thermal conductivity of sedimentary rocks is an important parameter in basin modelling as the main parameter controlling the temperature within a sedimentary basin. This thesis presents measured thermal conductivities, mainly on clay- and mudstone. The measured values are compared with values obtained by using thermal conductivity models. Some new thermal conductivity models are developed based on the measured values. The values obtained are less than most previously published values. In a study of unconsolidated sediments a constant deviation was found between thermal conductivities measured with a needle probe and a divided bas apparatus. Accepted thermal conductivity models based on the geometric mean model fail to predict the thermal conductivity of clay- and mudstone. Despite this, models based on the geometric mean model, where the effect of porosity is taken account of by the geometric mean equation, seem to be the best. Existing models underestimate the textural influence on the thermal conductivity of clay- and mudstone. The grain size was found to influence the thermal conductivity of artificial quartz samples. The clay mineral content seems to be a point of uncertainty in both measuring and modelling thermal conductivity. A good universal thermal conductivity model must include many mineralogical and textural factors. Since this is difficult, different models restricted to specific sediment types and textures are suggested to be the best solution to obtain realistic estimates applicable in basin modelling. 243 refs., 64 figs., 31 tabs.

Reactive Transport Modeling Investigation of High Dissolved Sulfide Concentrations in Sedimentary Basin Rocks

Science.gov (United States)

Xie, M.; Mayer, U. K.; MacQuarrie, K. T. B.

2017-12-01

Water with total dissolved sulfide in excess of 1 mmol L-1is widely found in groundwater at intermediate depths in sedimentary basins, including regions of the Michigan basin in southeastern Ontario, Canada. Conversely, at deeper and shallower depths, relatively low total dissolved sulfide concentrations have been reported. The mechanisms responsible for the occurrence of these brackish sulfide-containing waters are not fully understood. Anaerobic microbial sulfate reduction is a common process resulting in the formation of high sulfide concentrations. Sulfate reduction rates depend on many factors including the concentration of sulfate, the abundance of organic substances, redox conditions, temperature, salinity and the species of sulfate reducing bacteria (SRB). A sedimentary basin-specific conceptual model considering the effect of salinity on the rate of sulfate reduction was developed and implemented in the reactive transport model MIN3P-THCm. Generic 2D basin-scale simulations were undertaken to provide a potential explanation for the dissolved sulfide distribution observed in the Michigan basin. The model is 440 km in the horizontal dimension and 4 km in depth, and contains fourteen sedimentary rock units including shales, sandstones, limestones, dolostone and evaporites. The main processes considered are non-isothermal density dependent flow, kinetically-controlled mineral dissolution/precipitation and its feedback on hydraulic properties, cation exchange, redox reactions, biogenic sulfate reduction, and hydromechanical coupling due to glaciation-deglaciation events. Two scenarios were investigated focusing on conditions during an interglacial period and the transient evolution during a glaciation-deglaciation cycle. Inter-glaciation simulations illustrate that the presence of high salinity brines strongly suppress biogenic sulfate reduction. The transient simulations show that glaciation-deglaciation cycles can have an impact on the maximum depth of

Glendonites in Neoproterozoic low-latitude, interglacial, sedimentary rocks, northwest Canada: Insights into the Cryogenian ocean and Precambrian cold-water carbonates

Science.gov (United States)

James, Noel P.; Narbonne, Guy M.; Dalrymple, Robert W.; Kurtis Kyser, T.

2005-01-01

Stellate crystals of ferroan dolomite in neritic siliciclastic and carbonate sedimentary rocks between Sturtian and Marinoan glaciations in the Mackenzie Mountains are interpreted as replaced glendonites. These pseudomorphs after ikaite indicate that shallow seawater at that time was near freezing. Stromatolites verify that paleoenvironments were in the photic zone and physical sedimentary structures such as hummocky cross-bedding confirm that the seafloor was repeatedly disturbed by storms. Glendonites within these low-latitude, continental shelf to coastal sedimentary deposits imply that global ocean water during much of Cryogenian time was likely very cold. Such an ocean would easily have cooled to yield widespread sea ice and, through positive feedback, growth of low-latitude continental glaciers. In this situation gas hydrates could have formed in shallow-water, cold shelf sediment, but would have been particularly sensitive to destabilization as a result of sea-level change. Co-occurrence of pisolites and glendonites in these rocks additionally implies that some ooids and pisoids might have been, unlike Phanerozoic equivalents, characteristic of cold-water sediments.

The Totumo mud volcano and its near-shore marine sedimentological setting (North Colombia) - From sedimentary volcanism to epithermal mineralization

Science.gov (United States)

Dill, H. G.; Kaufhold, S.

2018-04-01

The Holocene mud volcano exposed at Totumo (younger than 4150 ± 50 yr BP) lines up together with some other landforms of its kind along the Caribbean Coast in northern Colombia. It currently vents a mud of the silicate-phosphate-bearing sulfur-sodium chloride type. The mud volcanoes evolved in an active continental margin setting of the South American Cordillera with high seismicity and affected by pervasive neotectonic structural disturbances. During the Neogene and Quaternary linear terrigenous shoreline sediments alternating with delta deposits evolved on this mobile crustal segment between the Andes and ancient Precambrian cratons. Meso- to microtidal sedimentary settings during transgression and progradation created meta- to instable sedimentary and petrophysical conditions (e.g. overpressure and gas-bearing bubble sands), favorable for the formation of mud volcanoes, whose lithofacies is subdivided into (1) footwall facies (detritus from metabasic, -pelitic source rocks), (2) mud volcano plus lateral facies (material from deep-seated hydrothermal sources, hydrocarbon plays, and brine reflux from the sea), (3) hanging wall facies, sand characterized by a strong longshore drift. The sedimentary volcanism in the area is characterized by different temperatures of formation: (1) pre-stage (oxides, garnet, alumosilicates, tourmaline, zircon, barite, Fe sulfides and -sulfates), light (Ca sulfates, calcite, quartz, feldspar) and clay minerals (kaolinite, mica, pyrophyllite, chlorite, vermiculite) are efficient tools to determine the source of mud, to subdivide the mud volcano system as to its facies and describe its physical-chemical regime as to the temperature of formation, pH and Eh values. The mud volcano system of Totumo bridges the gap between sedimentary "volcanism" and epithermal hot spring deposits of intermediate to high sulfidation and forms a useful "guide" to hydrocarbon accumulation.

Preliminary study of Precambrian integration with tectonic events in brazilian sedimentary basins (Updated); Estudo preliminar de integracao do Pre-Cambriano com os eventos tectonicos das bacias sedimentares brasileiras (Atualizacao)

Energy Technology Data Exchange (ETDEWEB)

Cordani, Umberto G. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Centro de Pesquisas Geocronologicas], Email: ucordani@usp.br; Neves, Benjamim Bley de Brito [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica], Email: bbleybn@usp.br; Thomaz Filho, Antonio [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Fac. de Geologia. Dept. de Estratigrafia e Paleontologia], Email: antoniothomaz@globo.com

2008-11-15

The article 'Preliminary study of Precambrian integration with tectonic events in Brazilian sedimentary basins,' by U. G. Cordani, B. B. Brito-Neves, R. A. Fuck, R. Porto, A. Thomaz-Filho and F. M. B. da Cunha, was published in PETROBRAS Petroleum Technical Science Series (Serie Ciencia Tecnica Petroleo da PETROBRAS) in 1984 and is being reissued by PETROBRAS Geosciences Bulletin. Naturally, the work requires many updates in the light of geosciences' progress in Brazil over the past 26 years. In these comments, numerous reflections have been addressed at short notice, but nevertheless considered appropriate, to occupy space conceded by the publishers for an assessment of the original work. In principle, only the latest summaries and newer published items on the topic have been consulted and commented. For this reason, it was decided to 'overlook' a number of important references on this issue, apologizing to the authors of omitted relevant works. The study, conducted in the early '80s, was based on the knowledge at the time regarding the tectonic evolution of the South American basement; an examination of PETROBRAS subsurface data in Brazilian sedimentary basins and the study of the Company's core samples obtained from perforations which reached the basement. Since then, great advances have been made in understanding the Brazilian territory tectonic evolution and important geophysical data collected regarding its sedimentary basins. On the other hand, there are virtually no recent perforations of the interior Cratonic basins. Moreover, in the marginal and offshore basins, many wells have not reached the basement. Therefore, in these comments, we sought to review the original study's interpretations and confirm the relevant geological knowledge added in recent decades, in the range of the original work. In this article, we try to follow the same structural sequence of the original text, giving the reader a better understanding

Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change

Science.gov (United States)

Arauza, Hanna M.; Simms, Alexander R.; Bement, Leland C.; Carter, Brian J.; Conley, Travis; Woldergauy, Ammanuel; Johnson, William C.; Jaiswal, Priyank

2016-01-01

Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.

Morphodynamics and sedimentary structures of bedforms under supercritical-flow conditions: new insights from flume experiments

Science.gov (United States)

Cartigny, Matthieu; Ventra, Dario; Postma, George; Van den Berg, Jan H.

2014-05-01

Supercritical-flow phenomena are fairly common in modern sedimentary environments, yet their recognition remains subordinate in the rock record. This is commonly ascribed to the poor preservation potential of deposits from supercritical flows. However, the number of documented flume datasets on supercritical-flow dynamics and sedimentary structures is very limited in comparison with available data from subcritical-flow experiments, and our inability to identify and interpret such deposits might also be due to insufficient knowledge. This article describes the results of systematic experiments spanning the full range of supercritical-flow bedforms (antidunes, chutes-and-pools, cyclic steps) developed over mobile sand beds of variable grain sizes. Flow character and related bedform patterns are constrained through time-series measurements of the bed configuration, flow depth, flow velocity and Froude number. The results allow the refinement and extension of current bedform stability diagrams in the supercritical-flow domain. The experimental dataset and the stability diagram clarify morphodynamic relationships between antidune and cyclic steps. The onset of antidunes is controlled by the flow passing a threshold value of the Froude parameter. The transition from antidunes to cyclic steps instead is completed at a threshold value of the mobility parameter, and this transition spans a wider range of values for the mobility parameter as grain size increases. Sedimentary structures associated with the development of supercritical bedforms under variable aggradation rates are revealed by means of a synthetic aggradation technique and compared with examples from field and flume studies. Aggradation rate bears an important influence on the geometry of supercritical structures, and it should be held in consideration for the identification and mutual distinction of supercritical-flow bedforms in the stratigraphic record.

Urban-touristic impacts on the aeolian sedimentary systems of the Canary Islands: conflict between development and conservation

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Leví García-Romero

2016-05-01

Full Text Available Aeolian sedimentary systems in the Canary Islands differ significantly from other European and African systems due to their natural characteristics (climate, vegetation and insular isolation. Consequently, their geomorphological processes are unique. In turn, they are areas under high human pressure from touristic development. The aim of this paper is to analyze the impacts of urban-touristic development in four aeolian sedimentary systems in the Canaries: Maspalomas, Corralejo, Lambra and Jable Sur. Spatial and surface changes of variables related to geomorphology and vegetation are obtained by photo-interpretation of historical aerial photography and current orthophotos. The results indicate that the systems affected by urban-touristic development have experienced significant environmental changes. In contrast, the systems that have not been affected by building and construction of infrastructure show minor changes.

Recirculation System for Geothermal Energy Recovery in Sedimentary Formations: Laboratory Experiments and Numerical Simulations

Science.gov (United States)

Elkhoury, J. E.; Detwiler, R. L.; Serajian, V.; Bruno, M. S.

2012-12-01

Geothermal energy resources are more widespread than previously thought and have the potential for providing a significant amount of sustainable clean energy worldwide. In particular, hot permeable sedimentary formations provide many advantages over traditional geothermal recovery and enhanced geothermal systems in low permeability crystalline formations. These include: (1) eliminating the need for hydraulic fracturing, (2) significant reduction in risk for induced seismicity, (3) reducing the need for surface wastewater disposal, (4) contributing to decreases in greenhouse gases, and (5) potential use for CO2 sequestration. Advances in horizontal drilling, completion, and production technology from the oil and gas industry can now be applied to unlock these geothermal resources. Here, we present experimental results from a laboratory scale circulation system and numerical simulations aimed at quantifying the heat transfer capacity of sedimentary rocks. Our experiments consist of fluid flow through a saturated and pressurized sedimentary disc of 23-cm diameter and 3.8-cm thickness heated along its circumference at a constant temperature. Injection and production ports are 7.6-cm apart in the center of the disc. We used DI de-aired water and mineral oil as working fluids and explored temperatures from 20 to 150 oC and flow rates from 2 to 30 ml/min. We performed experiments on sandstone samples (Castlegate and Kirby) with different porosity, permeability and thermal conductivity to evaluate the effect of hydraulic and thermal properties on the heat transfer capacity of sediments. The producing fluid temperature followed an exponential form with time scale transients between 15 and 45 min. Steady state outflow temperatures varied between 60% and 95% of the set boundary temperature, higher percentages were observed for lower temperatures and flow rates. We used the flow and heat transport simulator TOUGH2 to develop a numerical model of our laboratory setting. Given

Pre- and post-industrial environmental changes as revealed by the biogeochemical sedimentary record of Drammensfjord, Norway

NARCIS (Netherlands)

Smittenberg, R.H.; Baas, M.; Green, M.J.; Hopmans, E.C.; Schouten, S.; Sinninghe Damsté, J.S.

2005-01-01

The biogeochemical sedimentary record of the anoxic Drammensfjord, Norway, was investigated on a decadal to centennial time scale over the last millennium, in order to reconstruct the pre-industrial fjord environment and ecosystem and humaninduced environmental changes. The sediments were dated by

Pre- and post-industrial environmental changes as revealed by the biogeochemical sedimentary record of Drammensfjord, Norway

NARCIS (Netherlands)

Sinninghe Damsté, J.S.; Smittenberg, R.H.; Baas, M.; Green, M.J.; Hopmans, E.C.; Schouten, S.

2005-01-01

The biogeochemical sedimentary record of the anoxic Drammensfjord, Norway, was investigated on a decadal to centennial time scale over the last millennium, in order to reconstruct the pre-industrial fjord environment and ecosystem and human-induced environmental changes. The sediments were dated by

Hydrogeology of exogenic epigenic uranium deposits (sedimentary type) in Uzbekistan

International Nuclear Information System (INIS)

Irgashev, Yu.I.; Gavrilov, V.A.; Muslimov, B.A.

1996-01-01

Common problems of hydrogeology and geotechnology for uranium deposits (sedimentary type) in the Republic of Uzbekistan are discussed in the paper. Hydrogeology includes studies of texture of water-bearing horizons, occurrences of ore bodies in horizons, hydrochemical survey, hydrodynamics and engineering geology. Features of deposits workable by underground leaching are presented. Such terms as 'water-bearing horizon', 'efficiency', 'water-bearing bed' are explained accounting the results of 30 year investigations conducted during prospecting, designing and exploitation of uranium deposits. Stages of hydrogeological survey are listed and features of each of them are described. Importance of geotechnology for a deposit characterization is shown. (author). 6 refs.; 1 fig.; 1 tab

Induced polarization and electromagnetic field surveys of sedimentary uranium deposits

International Nuclear Information System (INIS)

Campbell, D.L.; Smith, B.D.

1985-01-01

Induced polarization (IP) and electromagnetic (EM) geophysical surveys were made over three areas of sedimentary uranium deposits in the western United States. The EM techniques were sometimes useful for investigating general structural settings, but not for finding uranium deposits per se. IP techniques were useful to help pinpoint zones of disseminated pyrite associated with the uranium deposits. In one case no clear differences were seen between the IP signatures of oxidized and reduced ground. Spectral (multi-frequency) IP showed no particular advantages over conventional IP for exploration applications. A sediment mineralization factor is introduced comparable to the ''metal factor'' used to detect porphyry copper mineralization. (author)

The influence of delta formation mechanism on geotechnical property sequence of the late Pleistocene–Holocene sediments in the Mekong River Delta

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Truong Minh Hoang

2016-11-01

Full Text Available The aim of the study was to characterize a variety of microstructure development-levels and geotechnical property sequences of the late Pleistocene–Holocene deposits in the Mekong River delta (MRD, and the paper furthermore discusses the influences of delta formation mechanisms on them. The survey associated the geotechnical engineering and the sedimentary geology of the late Pleistocene–Holocene deposits at five sites and also undifferentiated Pleistocene sediments. A cross-section which was rebuilt in the delta progradation-direction and between the Mekong and Bassac rivers represents the stratigraphy. Each sedimentary unit was formed under a different delta formation mechanism and revealed a typical geotechnical property sequence. The mechanical behaviors of the sediment succession in the tide-dominated delta with significant fluvial-activity and material source tend to be more cohesionless soils and strengths than those in the tide- and wave-dominated delta and even the coast. The particular tendency of the mechanical behavior of the deposit succession can be reasonably estimated from the delta formation mechanism. The characteristics of the clay minerals from the Mekong River produced the argillaceous soil which does not have extremely high plasticity. The microstructure development-levels are low to very high indicating how to choose hydraulic conductivity value, k, for estimating overconsolidation ratio, OCR, by the piezocone penetration tests (CPTU. The OCR of sediments in the delta types strangely change with depth but none less than 1. The post-depositional processes significantly influenced the microstructure development, particularly the dehydrating and oxidizing processes.

Formation mechanisms and sequence response of authigenic grain-coating chlorite: evidence from the Upper Triassic Xujiahe Formation in the southern Sichuan Basin, China

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Yu Yu

2016-11-01

Full Text Available Abstract Authigenic grain-coating chlorite is widely distributed in the clastic rocks of many sedimentary basins around the world. These iron minerals were mainly derived from flocculent precipitates formed when rivers flow into the ocean, especially in deltaic environments with high hydrodynamic conditions. At the same time, sandstone sequences with grain-coating chlorites also tend to have relatively high glauconite and pyrite content. EPMA composition analysis shows that glauconites with “high Al and low Fe” content indicate slightly to semi-saline marine environments with weak alkaline and weakly reducing conditions. By analyzing the chlorite-containing sandstone bodies of the southern Sichuan Xujiahe Formation, this study found that chlorite was mainly distributed in sedimentary microfacies, including underwater distributary channels, distributary channels, shallow lake sandstone dams, and mouth bars. Chlorite had a tendency to form in the upper parts of sandstone bodies with signs of increased base level, representing the influence of marine (lacustrine transgression. This is believed to be influenced by megamonsoons in the Middle and Upper Yangtze Region during the Late Triassic Epoch. During periods of abundant precipitation, river discharges increased and more Fe particulates flowed into the ocean (lake. In the meantime, increases or decreases in lake level were only affected by precipitation for short periods of time. The sedimentary environment shifted from weakly oxidizing to weak alkaline, weakly reducing conditions as sea level increased, and Fe-rich minerals as authigenic chlorite and glauconite began to form and deposit.

Depositional setting analysis using seismic sedimentology: Example from the Paleogene Lishagang sequence in the Fushan depression, South China Sea

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Yuan Li

2017-09-01

Full Text Available The Fushan depression is a classic lacustrine rifted sub-basin in the Beibuwan Basin, South China Sea. The Paleogene Liushagang sequence is the main hydrocarbon-bearing stratigraphic unit in the depression. Using three-dimensional (3-D seismic data and logging data, we analyzed depositional setting of the Liushagang sequence. We use wave impedance inversion to describe progradational directions of provenance and the general distribution of sand body. The seismic facies was analyzed by using the seismic sedimentology approach based on 3-D seismic data, and summed into eight types of seismic facies which could be well related to sedimentary facies. Seismic attributes with six objective sequence boundaries were extracted. Consequently, four provenance system of Liushagang sequence in the study area were confirmed by the corresponding relationship between the geologic information and the warm color and higher value area of seismic attributes: (i the Hainan uplift provenance area in the south, (ii the Linggao uplift provenance area in the west, (iii the Yunlong uplift provenance area in the east and (iv the northern provenance area. The seismic sedimentology used in this study may provide new insights into a better understanding of depositional setting in continental lacustrine rifted basins.

Modeling the Sedimentary Infill of Lakes in the East African Rift: A Case Study of Multiple versus Single Rift Basin Segments

Science.gov (United States)

Zhang, C.; Scholz, C. A.

2016-12-01

The sedimentary basins in the East African Rift are considered excellent modern examples for investigating sedimentary infilling and evolution of extensional systems. Some lakes in the western branch of the rift have formed within single-segment systems, and include Lake Albert and Lake Edward. The largest and oldest lakes developed within multi-segment systems, and these include Lake Tanganyika and Lake Malawi. This research aims to explore processes of erosion and sedimentary infilling of the catchment area in single-segment rift (SSR) and multi-segment rift (MSR) systems. We consider different conditions of regional precipitation and evaporation, and assess the resulting facies architecture through forward modeling, using state-of-the-art commercial basin modeling software. Dionisos is a three-dimensional numerical stratigraphic forward modeling software program, which simulates basin-scale sediment transport based on empirical water- and gravity-driven diffusion equations. It was classically used to quantify the sedimentary architecture and basin infilling of both marine siliciclastic and carbonate environments. However, we apply this approach to continental rift basin environments. In this research, two scenarios are developed, one for a MSR and the other for a SSR. The modeled systems simulate the ratio of drainage area and lake surface area observed in modern Lake Tanganyika and Lake Albert, which are examples of MSRs and SSRs, respectively. The main parameters, such as maximum subsidence rate, water- and gravity-driven diffusion coefficients, rainfall, and evaporation, are approximated using these real-world examples. The results of 5 million year model runs with 50,000 year time steps show that MSRs are characterized by a deep water lake with relatively modest sediment accumulation, while the SSRs are characterized by a nearly overfilled lake with shallow water depths and thick sediment accumulation. The preliminary modeling results conform to the features

Inclination shallowing in Eocene Linzizong sedimentary rocks from Southern Tibet: correction, possible causes and implications for reconstructing the India-Asia collision

Science.gov (United States)

Huang, Wentao; Dupont-Nivet, Guillaume; Lippert, Peter C.; van Hinsbergen, Douwe J. J.; Hallot, Erwan

2013-09-01

A systematic bias towards low palaeomagnetic inclination recorded in clastic sediments, that is, inclination shallowing, has been recognized and studied for decades. Identification, understanding and correction of this inclination shallowing are critical for palaeogeographic reconstructions, particularly those used in climate models and to date collisional events in convergent orogenic systems, such as those surrounding the Neotethys. Here we report palaeomagnetic inclinations from the sedimentary Eocene upper Linzizong Group of Southern Tibet that are ˜20° lower than conformable underlying volcanic units. At face value, the palaeomagnetic results from these sedimentary rocks suggest the southern margin of Asia was located ˜10°N, which is inconsistent with recent reviews of the palaeolatitude of Southern Tibet. We apply two different correction methods to estimate the magnitude of inclination shallowing independently from the volcanics. The mean inclination is corrected from 20.5° to 40.0° within 95 per cent confidence limits between 33.1° and 49.5° by the elongation/inclination (E/I) correction method; an anisotropy-based inclination correction method steepens the mean inclination to 41.3 ± 3.3° after a curve fitting- determined particle anisotropy of 1.39 is applied. These corrected inclinations are statistically indistinguishable from the well-determined 40.3 ± 4.5º mean inclination of the underlying volcanic rocks that provides an independent check on the validity of these correction methods. Our results show that inclination shallowing in sedimentary rocks can be corrected. Careful inspection of stratigraphic variations of rock magnetic properties and remanence anisotropy suggests shallowing was caused mainly by a combination of syn- and post-depositional processes such as particle imbrication and sedimentary compaction that vary in importance throughout the section. Palaeolatitudes calculated from palaeomagnetic directions from Eocene sedimentary

Revised stratigraphy and reinterpretation of the Miocene Pohang basinfill, SE Korea: sequence development in response to tectonism and eustasy in a back-arc basin margin

Science.gov (United States)

Sohn, Y. K.; Rhee, C. W.; Shon, H.

2001-09-01

The Miocene Pohang Basin is a pull-apart basin formed along the eastern continental margin of Korea (ECMK) during the back-arc opening of the East Sea (Sea of Japan). The basin is filled by more than 1 km thick, nonmarine to deep-marine strata. These strata show extreme vertical and lateral lithofacies changes and have caused decades-long controversies on their nature and stratigraphy. Previous sedimentological studies suggest that the basinfill was deposited by a series of contemporaneously developed depositional systems, including fan delta, prodelta, slope apron, and basin plain. Detailed mapping and magnetotelluric surveying show, however, that the basinfill is composed of several packages of strata (sequences) that are bounded by distinct and laterally persistent stratigraphic discontinuities (sequence boundaries). This suggests that the depositional systems in the Pohang Basin developed sequentially rather than contemporaneously. Six packages of strata are identified in the basin: a nonmarine to shallow marine (transgressive) sequence (Sequence 1), a Gilbert-type-delta conglomerate (Sequence 2), and alternations of submarine conglomerates and hemipelagic mudstones (Sequences 3-6). The conglomerates and hemipelagic mudstones of the latter four sequences are interpreted to represent lowstand depositional systems (slope apron, submarine fan, and high-gradient delta) and condensed intervals, respectively. Compilation of geochronologic, paleomagnetic, and biostratigraphic data suggests that Sequence 1 formed during the gradual subsidence of the ECMK prior to 17 Ma, whereas Sequence 2 formed in response to abrupt downfaulting of the Pohang Basin at about 17 Ma. Both sequences are interpreted to have developed in response to the early Miocene back-arc-opening tectonism of the East Sea. On the other hand, Sequences 3-6 formed between 17 and about 10.5 Ma. The Pohang Basin was subject to only minor tectonism during this period and could record global sea

Application of /sup 14/C-dating to sedimentary geology and climatology: Sea-level and climate change during the Holocene

Energy Technology Data Exchange (ETDEWEB)

Nakai, Nobuyuki; Ohishi, Shyoji; Kuriyama, Toyoko; Nakamura, Toshio

1987-11-01

AMS /sup 14/C dating of small sized fossil shells, wood chips and sedimentary humic matter has been applied to the investigation of paleoclimatic and sea-level changes in the Holocene, using three estuarine and brackish lake sediment cores, drilled in Kawasaki city and Lake Hamanako, Japan. Precise and detailed ages at differing depths clarified large transitions of Holocene sedimentation rates, of two orders of magnitude. The vertical variation in delta/sup 13/C and C/N results for sedimentary organic matter, combined with AMS /sup 14/C ages, established continous climatic and sea-level fluctuation patterns through time and indicated the existence of neoglaciation coincident with the marine regression at 7500 to 7000 yr BP.

Microfacies, Sedimentary Environment and Relative Sea Level Changes of the Ruteh Formation, Sangsar and Makaroud Sections, Central Alborz

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Leili Bastami

2016-12-01

-red S solution according to Dickson (1965 method. The grain and matrix percentages were estimated using visual percentage charts of Bacelle and Bosellini (1965. Dunham (1962 classification were used for carbonate facies nomenclature. Based on lithological and textural characteristics, fossil content, abiotic allochems, facies succession and their comparision with well studied environments by Flugel (2010, microfacies and their subenvironments have been identified. In this study investigation of relative sea level changes is on the basis of field observations and facies analysis. Based on the vertical succession of microfacies and sedimentary paleoenvironmental features, Systems tracts and sedimentary sequences have been recognized. Discussion of Results & Conclusions Field and petrographic studies at the Sangsar and Makaroud sections, indicate that the Ruteh Formation sediments consist of 19 carbonate microfacies and one siliciclastic petrofacies that during the Middle Permian times deposited in tidal flat to open marine facies belts of a bioclastic homoclinal carbonate ramp on the southern passive margin of the Paleotethys located on the northern Gondwana Supercontinent in a tropical region. Tidal flat facies belt includes: Dolomitic mudstone, lime mudstone to sandy lime mudstone, pelloid intraclast packstone and one quartzarenite siliciclastic petrofacies. Lagoon facies belt includes: bioclast mudstone, dasycladacea wackestone, foraminifera pelloid wackestone, bioclast pelloid wackestone,  bioclast tubiphytes wackestone, bioclast algal wackestone/packstone. Shoal facies belt includes: ooid pelloid packstone/grainstone, bioclast pelloid packstone/grainstone, pelloid bioclast grainstone and algal packstone/grainstone. Open marine facies belt includes: tubiphytes gymnocodiacea wackestone, gymnocodiacea packstone, bioclast gymnocodiacea wackestone, sponge spicule bioclast wackestone, crinoid mudstone/wackestone and bioclast mudstone.  The Ruteh Formation at both

Deep sedimentary structure model beneath the Osaka plain; Osaka heiya ni okeru shinbu chika kozo no model ka

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Miyakoshi, K; Kagawa, T; Echigo, T [Osaka Soil Test, Osaka (Japan)

1997-05-27

Restructuring was carried out on a sedimentary basin structure model of the Osaka plain including Osaka Bay by using newly obtained underground structural data. After the Hygoken-nanbu Earthquake of 1995, a large number of underground structure investigations have been performed in Osaka Bay and urban areas of Kobe and Osaka. However, very few surveys have been done in areas peripheral to Osaka Prefecture, such as the Ikoma area. Therefore, an attempt has been made to increase the number of measuring points to acquire underground structural data of these areas. Estimation of basic rock depths has utilized the dominant cycles in H/V spectra obtained from micro vibration survey, and good correlation of the base rock depths derived by a refraction exploration and a deep-bed boring investigation. With regard to bed division and P- and S- wave velocities in sedimentary beds in the Osaka sedimentary basin, an underground structure model was prepared, which was divided into four beds according to the refraction exploration and the micro vibration investigation. Data obtained by using this model agreed well with depth data acquired from physical exploration and other types of investigations. However, no good agreement was recognized in the data for such areas where the basic depth changes abruptly as the Rokko fault and the Osaka bay fault. 6 refs., 8 figs., 2 tabs.

Elemental Characteristics of Australian Sedimentary Opals and their Implications for Opal Formation and Gemstone Fingerprinting

Science.gov (United States)

Dutkiewicz, A.; Landgrebe, T. C.; Rey, P. F.

2011-12-01

Opal consists of amorphous SiO2.nH2O comprising a network of silica spheres, which in precious opal are of similar size and form an ordered network allowing light to diffract into an array of colors. Common opal, which is often associated with precious opal, lacks this play of color as it is composed of silica spheres of variable sizes. Australia supplies over 95% of the world's precious opal. The opal is almost exclusively located within Cretaceous sedimentary rocks of the Great Artesian Basin, which experienced a major phase of uplift in the Late Cretaceous with subsequent erosion removing a package of sedimentary rock up to 3 km in thickness. Intense weathering resulted in extensive silicification at relatively shallow levels within the Tertiary regolith. However, despite a billion dollar industry and a well-constrained geological history of the basin, the formation of sedimentary opal and its uniqueness to the Australian continent are still very poorly understood. In this study we have used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on precious and common opal from key opal mining areas in order to constrain the possible sources of silica fluids involved in opal genesis and to assess whether any major or trace elements could be used to determine the provenance of opal with respect to a particular mining area. A total of 123 spots, each comprising 59 elements, including rare earth elements were analyzed. Globally, volcanic and sedimentary opals can be distinguished on the basis of Ba and Ca concentrations. Although the opals from the Great Artesian Basin are all sedimentary, some show Ba concentrations consistent with volcanic opals suggesting that silica fluids from which they formed were derived from a volcanic province. The most likely source is the Cretaceous volcanic-plutonic province of central Queensland, which supplied vast amounts of volcanogenic material into the Great Artesian Basin. The weathering of feldspars from the

Sequence of structures in fine-grained turbidites: Comparison of recent deep-sea and ancient flysch sediments

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Stow, Dorrik A. V.; Shanmugam, Ganapathy

1980-01-01

A comparative study of the sequence of sedimentary structures in ancient and modern fine-grained turbidites is made in three contrasting areas. They are (1) Holocene and Pleistocene deep-sea muds of the Nova Scotian Slope and Rise, (2) Middle Ordovician Sevier Shale of the Valley and Ridge Province of the Southern Appalachians, and (3) Cambro-Ordovician Halifax Slate of the Meguma Group in Nova Scotia. A standard sequence of structures is proposed for fine-grained turbidites. The complete sequence has nine sub-divisions that are here termed T 0 to T 8. "The lower subdivision (T 0) comprises a silt lamina which has a sharp, scoured and load-cast base, internal parallel-lamination and cross-lamination, and a sharp current-lineated or wavy surface with 'fading-ripples' (= Type C etc. …)." (= Type C ripple-drift cross-lamination, Jopling and Walker, 1968). The overlying sequence shows textural and compositional grading through alternating silt and mud laminae. A convolute-laminated sub-division (T 1) is overlain by low-amplitude climbing ripples (T 2), thin regular laminae (T 3), thin indistinct laminae (T 4), and thin wipsy or convolute laminae (T 5). The topmost three divisions, graded mud (T 6), ungraded mud (T 7) and bioturbated mud (T 8), do not have silt laminae but rare patchy silt lenses and silt pseudonodules and a thin zone of micro-burrowing near the upper surface. The proposed sequence is analogous to the Bouma (1962) structural scheme for sandy turbidites and is approximately equivalent to Bouma's (C)DE divisions. The repetition of partial sequences characterizes different parts of the slope/base-of-slope/basin plain environment, and represents deposition from different stages of evolution of a large, muddy, turbidity flow. Microstructural detail and sequence are well preserved in ancient and even slightly metamorphosed sediments. Their recognition is important for determining depositional processes and for palaeoenvironmental interpretation.

The Jurassic of Denmark and Greenland: The Jurassic of East Greenland: a sedimentary record of thermal subsidence, onset and culmination of rifting

Directory of Open Access Journals (Sweden)

Surlyk, Finn

2003-10-01

Full Text Available The Late Palaeozoic – Mesozoic extensional basin complex of East Greenland contains a record of deposition during a period of Rhaetian – Early Bajocian thermal subsidence, the onset of riftingin the Late Bajocian, its growth during the Bathonian–Kimmeridgian, culmination of rifting in the Volgian – Early Ryazanian, and waning in the Late Ryazanian – Hauterivian. The area was centred over a palaeolatitude of about 45°N in the Rhaetian and drifted northwards to about 50°N in the Hauterivian. A major climate change from arid to humid subtropical conditions took place at the Norian–Rhaetian transition. Deposition was in addition governed by a long-term sea-level rise with highstands in the Toarcian–Aalenian, latest Callovian and Kimmeridgian, and lowstands in the latest Bajocian – earliest Bathonian, Middle Oxfordian and Volgian.The Rhaetian – Lower Bajocian succession is considered the upper part of a megasequence, termed J1, with its base in the upper Lower Triassic, whereas the Upper Bajocian – Hauterivian succession forms a complete, syn-rift megasequence, termed J2. The southern part of the basin complex in Jameson Land contains a relatively complete Rhaetian–Ryazanian succession and underwent only minor tilting during Middle Jurassic – earliest Cretaceous rifting. Rhaetian – Lower Jurassic deposits are absent north of Jameson Land and this region was fragmented into strongly tilted fault blocks during the protracted rift event. The syn-rift successions of the two areas accordingly show different long-term trends in sedimentary facies. In the southern area, the J2 syn-rift megasequence forms a symmetrical regressive–transgressive–regressive cycle, whereas the J2 megasequence in the northern area shows an asymmetrical, stepwise deepening trend.A total of eight tectonostratigraphic sequences are recognised in the Rhaetian–Hauterivian interval. They reflect major changes in basin configuration, drainage systems

Sedimentary basins reconnaissance using the magnetic Tilt-Depth method

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Salem, A.; Williams, S.; Samson, E.; Fairhead, D.; Ravat, D.; Blakely, R.J.

2010-01-01

We compute the depth to the top of magnetic basement using the Tilt-Depth method from the best available magnetic anomaly grids covering the continental USA and Australia. For the USA, the Tilt-Depth estimates were compared with sediment thicknesses based on drilling data and show a correlation of 0.86 between the datasets. If random data were used then the correlation value goes to virtually zero. There is little to no lateral offset of the depth of basinal features although there is a tendency for the Tilt-Depth results to be slightly shallower than the drill depths. We also applied the Tilt-Depth method to a local-scale, relatively high-resolution aeromagnetic survey over the Olympic Peninsula of Washington State. The Tilt-Depth method successfully identified a variety of important tectonic elements known from geological mapping. Of particular interest, the Tilt-Depth method illuminated deep (3km) contacts within the non-magnetic sedimentary core of the Olympic Mountains, where magnetic anomalies are subdued and low in amplitude. For Australia, the Tilt-Depth estimates also give a good correlation with known areas of shallow basement and sedimentary basins. Our estimates of basement depth are not restricted to regional analysis but work equally well at the micro scale (basin scale) with depth estimates agreeing well with drill hole and seismic data. We focus on the eastern Officer Basin as an example of basin scale studies and find a good level of agreement between previously-derived basin models. However, our study potentially reveals depocentres not previously mapped due to the sparse distribution of well data. This example thus shows the potential additional advantage of the method in geological interpretation. The success of this study suggests that the Tilt-Depth method is useful in estimating the depth to crystalline basement when appropriate quality aeromagnetic anomaly data are used (i.e. line spacing on the order of or less than the expected depth to

Hydrological evaluation of five sedimentary rocks for high-level waste disposal

International Nuclear Information System (INIS)

Lomenick, T.F.; Kanehiro, B.Y.

1986-01-01

Utilizing performance criteria that are based upon siting guidelines issued by DOE for postclosure as well as preclosure conditions, a preliminary hydrologic evaluation and ranking is being conducted to determine the suitability of five sedimentary rocks as potential host rocks for a high-level radioactive waste repository. Based upon both quantitative and qualitative considerations, the hydrological ranking of the rocks in order of their potential as a host rock for the disposal of radioactive wastes would be shale, anhydrock, sandstone, chalk, and carbonates, with the first three rocks being significantly better than the remaining two types

Morphology, sedimentary features and evolution of a large palaeo submarine canyon in Qiongdongnan basin, Northern South China Sea

Science.gov (United States)

Li, Xiangquan; Fairweather, Luke; Wu, Shiguo; Ren, Jianye; Zhang, Hongjie; Quan, Xiayun; Jiang, Tao; Zhang, Cheng; Su, Ming; He, Yunlong; Wang, Dawei

2013-01-01

The large Miocene-aged palaeo canyon that extents through the Qiongdongnan basin (QDNB) and Yinggehai basin (YGHB) of Northern South China Sea has been of considerable interest both economically and scientifically over the past decade. Stemmed from this, significant research has been employed into understanding the mechanism for its existence, incision, and sedimentary fill, yet debate remains. In the first case the canyon itself is actually quite anomalous. Alone from the size (over 570 km in length and more than 8 km in width (Yuan et al., 2009)), which is considerably more than most ancient deep-water channels (REFS), the canyon's sedimentary fill is also distinctly different. Some explanations have been given to explain the canyon's origin and existence, these include increased sediment supply from the Red River which is genetically linked to uplift of the Tibetan Plateau, lowstand turbidite and mass-transport activity, reactivation and dextral displacement of the Red River Fault zone inducing erosive gravity-flows, regional tilt of the QDNB and YGHB, paleo-seafloor morphology and seal-level fluctuations. With the application of new data obtained from interpretations of a large number of 2D seismic profiles, core and well log data, and tectonic and sedimentary analysis this contribution aims to: (1) Present models to explain the Canyon's sedimentary fill and basin plain deposits, which provided significant understanding of processes pre-, syn- and post-incision and; (2) review the plausibility and likelihood of each of the controlling mechanisms, hoping to shed light on this controversial aspect. We conclude that the final erosive event that shaped the canyon is dated at 5.5 Ma. The Canyon's unusual fill is a product of variation in the interaction between turbidity currents and MTD that blocked the canyon's axis, and the reduction in gravity flow energy through time; and therefore the complete succession represents one major erosive and cut event at 5.5 Ma and

Rb-Sr ages of Precambrian sedimentary rocks in the U.S.A

International Nuclear Information System (INIS)

Morton, J.P.; Long, L.E.

1982-01-01

Dating of Precambrian sedimentary rocks to determine the age of deposition has not been pursued as diligently in the U.S.A. as in other areas. Ages (which must be regarded as tentative) are summarized for the younger Precambrian stratified rocks of the Grand Canyon (Arizona), the Nonesuch Shale of the Keweenawan Series (Michigan), the Uinta Mountain Group (Utah), and the Belt-Supergroup (Idaho-Montana). An important question of interpretation is whether the ages correspond to times of deposition or of later diagenesis. (Auth.)

On the connectivity anisotropy in fluvial Hot Sedimentary Aquifers and its influence on geothermal doublet performance

DEFF Research Database (Denmark)

Willems, Cees J.L.; Nick, Hamid; Donselaar, Marinus E.

2017-01-01

This study finds that the geothermal doublet layout with respect to the paleo flow direction in fluvial sedimentary reservoirs could significantly affect pump energy losses. These losses can be reduced by up to 10% if a doublet well pair is oriented parallel to the paleo flow trend compared...

USING THE SEDIMENT QUALITY TRIAD (SQT) APPROACH TO ASSESS SEDIMENTARY CONTAMINATION IN THE ANACOSTIA RIVER, WASHINGTON

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Using the Sediment Quality Triad (SQT) Approach to Assess Sedimentary Contamination in the Anacostia River, Washington, D.C. Velinsky, DJ*1, Ashley, JTF1,2, Pinkney, F.3, McGee, BL3 and Norberg-King, TJ.4 1Academy of Natural Sciences-PCER, Philadelphia, PA. 2Philadelphia Universi...

Sedimentary and Vegetative Impacts of Hurricane Irma to Coastal Wetland Ecosystems across Southwest Florida

Science.gov (United States)

Moyer, R. P.; Khan, N.; Radabaugh, K.; Engelhart, S. E.; Smoak, J. M.; Horton, B.; Rosenheim, B. E.; Kemp, A.; Chappel, A. R.; Schafer, C.; Jacobs, J. A.; Dontis, E. E.; Lynch, J.; Joyse, K.; Walker, J. S.; Halavik, B. T.; Bownik, M.

2017-12-01

Since 2014, our collaborative group has been working in coastal marshes and mangroves across Southwest Florida, including Tampa Bay, Charlotte Harbor, Ten Thousand Islands, Biscayne Bay, and the lower Florida Keys. All existing field sites were located within 50 km of Hurricane Irma's eye path, with a few sites in the Lower Florida Keys and Naples/Ten Thousand Islands region suffering direct eyewall hits. As a result, we have been conducting storm-impact and damage assessments at these locations with the primary goal of understanding how major hurricanes contribute to and/or modify the sedimentary record of mangroves and salt marshes. We have also assessed changes to the vegetative structure of the mangrove forests at each site. Preliminary findings indicate a reduction in mangrove canopy cover from 70-90% pre-storm, to 30-50% post-Irma, and a reduction in tree height of approximately 1.2 m. Sedimentary deposits consisting of fine carbonate mud up to 12 cm thick were imported into the mangroves of the lower Florida Keys, Biscayne Bay, and the Ten Thousand Islands. Import of siliciclastic mud up to 5 cm thick was observed in Charlotte Harbor. In addition to fine mud, all sites had imported tidal wrack consisting of a mixed seagrass and mangrove leaf litter, with some deposits as thick as 6 cm. In areas with newly opened canopy, a microbial layer was coating the surface of the imported wrack layer. Overwash and shoreline erosion were also documented at two sites in the lower Keys and Biscayne Bay, and will be monitored for change and recovery over the next few years. Because active research was being conducted, a wealth of pre-storm data exists, thus these locations are uniquely positioned to quantify hurricane impacts to the sedimentary record and standing biomass across a wide geographic area. Due to changes in intensity along the storm path, direct comparisons of damage metrics can be made to environmental setting, wind speed, storm surge, and distance to eyewall.

Sequence stratigraphy from ``spot'' outcrops—example from a carbonate-dominated setting: Devonian-Carboniferous transition, Dinant synclinorium (Belgium)

Science.gov (United States)

Van Steenwinkel, M.

1990-12-01

The application of sequence stratigraphy appears to be perfectly valid in isolated "spot" outcrops, which usually are badly exposed and located in areas of strong tectonic overprint. The case study presented here is in a carbonate-dominated setting at the northern edge of the Cornwall-Rhenish basin, during latest Devonian and earliest Carboniferous times. The approach taken involved the analysis of facies and vertical facies evolutions, in combination with detailed biostratigraphy. The subsequent deduction of deepening and shallowing events, and the understanding of the sedimentary response to these events in different palaeogeographical positions, are the basis for lateral correlation of facies sequences. A similar trend in the changes of deepenings and shallowings throughout the area, regardless of lateral facies differentiation, indicates a relationship between bathymetric changes and relative sea-level changes, that is independent of local differences in the sedimentation or subsidence rates. The studied stratigraphic interval, with its apparently "abrupt" changes in facies or lithology, is the sedimentary response to six, gradually changing trends in the rate of relative sea-level fall and rise. End-Devonian, offshore highstand deposits (1) are capped by an unconformity surface or by a surface of submarine erosion and nondeposition, representing a sequence boundary (2). The overlying lowstand unit consists of a basal (3) and an upper (4) part. The basal part contains an oolitic and crinoidal sand shoals, associated with a transgressive lag deposit in offshore position; the upper, main part is a prograding wedge of shallow-marine crinoidal sands, intercalated with increasingly deeper-water shaly facies (higher-order fluctuation). This lowstand unit was deposited during the initial, slow phase of relative sea-level rise. It levelled the topographic relief before the final drowning during the subsequent rapid (near the rise inflection point) relative sea

Modeling of a sedimentary rock alternative for the siting of the radioactive waste disposal system

International Nuclear Information System (INIS)

Fuentes, Nestor O.

2007-01-01

Here are described the main concepts, the approximations, and all those simulation aspects that characterize the modeling performed using the unsaturated saturated approach for porous media. The objective of this work is to obtain a generic description of a sedimentary rock soil as an alternative site for the low and intermediate level radioactive waste disposal system. (author) [es

Continental sedimentary successions exposed in Centinela del Mar, Buenos Aires, Argentina (Lower Pleistocene - Holocene); Las sucesiones sedimentarias continentales expuestas en Centinela del Mar, provincia de Buenos Aires, Argentina (Pleistoceno Inferior-Holoceno)

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Cenizo, M. M.

2011-07-01

In the present paper, the geomorphologic and sedimentary characteristics of the continental sequences exposed on the coastal cliffs and surrounding areas of the Centinela del Mar locality are described and interpreted. Fourteen lithofacies are defined, their relation, geometry and structure are represented using transversal and longitudinal detailed profiles. In the basal and medium sector of the profile, facies of different degrees of transport and aqueous rework were recognized. In the superior sector, a succession of marine peri-coastal facies corresponding to the Belgranense transgression (=Fm. Pascua) were identified, ending the sequence with relictual eolic facies. The different historical interpretations are discussed, homologating the units referred previously with the ones proposed on this paper. These units are correlated with those defined in the allostratigrapic scheme proposed by other authors for the area covered between Playa San Carlos and Arroyo Chapadmalal. This allowed recognize for the area under study the presence of the Punta San Andres and Arroyo Loberia Alloformations (basal-medium and superior sector, respectively). Between these two entities, a association of well defined progradant marine facies are found and named on this paper as Centinela del Mar Alloformation. Finally, periferithe information gathered here (magnetostratigraphy, radiometric dating, stratigraphic correlations, etc) indicates, at least preliminarily, that the sequence of Centinela del Mar corresponds to the Ensenadense- Lujanense interval (Lower Pleistocene - Holocene). (Author) 73 refs.

Heterogeneous arsenic enrichment in meta-sedimentary rocks in central Maine, United States

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O' Shea, Beth, E-mail: bethoshea@sandiego.edu [Department of Marine Science and Environmental Studies, University of San Diego, 5998 Alcala Park, San Diego, CA 92110 (United States); Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 (United States); Stransky, Megan; Leitheiser, Sara [Department of Marine Science and Environmental Studies, University of San Diego, 5998 Alcala Park, San Diego, CA 92110 (United States); Brock, Patrick [School of Earth and Environmental Sciences, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367 (United States); Marvinney, Robert G. [Maine Geological Survey, 93 State House Station, Augusta, ME 04333 (United States); Zheng, Yan [School of Earth and Environmental Sciences, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367 (United States); Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 (United States)

2015-02-01

Arsenic is enriched up to 28 times the average crustal abundance of 4.8 mg kg{sup −1} for meta-sedimentary rocks of two adjacent formations in central Maine, USA where groundwater in the bedrock aquifer frequently contains elevated As levels. The Waterville Formation contains higher arsenic concentrations (mean As 32.9 mg kg{sup −1}, median 12.1 mg kg{sup −1}, n = 38) than the neighboring Vassalboro Group (mean As 19.1 mg kg{sup −1}, median 6.0 mg kg{sup −1}, n = 38). The Waterville Formation is a pelitic meta-sedimentary unit with abundant pyrite either visible or observed by scanning electron microprobe. Concentrations of As and S are strongly correlated (r = 0.88, p < 0.05) in the low grade phyllite rocks, and arsenic is detected up to 1944 mg kg{sup −1} in pyrite measured by electron microprobe. In contrast, statistically significant (p < 0.05) correlations between concentrations of As and S are absent in the calcareous meta-sediments of the Vassalboro Group, consistent with the absence of arsenic-rich pyrite in the protolith. Metamorphism converts the arsenic-rich pyrite to arsenic-poor pyrrhotite (mean As 1 mg kg{sup −1}, n = 15) during de-sulfidation reactions: the resulting metamorphic rocks contain arsenic but little or no sulfur indicating that the arsenic is now in new mineral hosts. Secondary weathering products such as iron oxides may host As, yet the geochemical methods employed (oxidative and reductive leaching) do not conclusively indicate that arsenic is associated only with these. Instead, silicate minerals such as biotite and garnet are present in metamorphic zones where arsenic is enriched (up to 130.8 mg kg{sup −1} As) where S is 0%. Redistribution of already variable As in the protolith during metamorphism and contemporary water–rock interaction in the aquifers, all combine to contribute to a spatially heterogeneous groundwater arsenic distribution in bedrock aquifers. - Highlights: • Arsenic is enriched up to 138 mg kg

Synchronous response of sedimentary organic carbon accumulation on the inner shelf of the East China Sea to the water impoundment of Three Gorges and Gezhouba Dams

Science.gov (United States)

Lin, Jia; Zhu, Qing; Hong, Yuehui; Yuan, Lirong; Liu, Jinzhong; Xu, Xiaoming; Wang, Jianghai

2018-01-01

Coastal seas, located between continents and the open ocean, are an important active carbon pool. The sedimentary total organic carbon (TOC) in these areas is a mixture of terrestrial and marine sources, and can be a powerful proxy for tracing natural processes and human activities. In this study, one fine-grained sediment core (DH5-1) from the inner shelf of the East China Sea was systematically analyzed for TOC and black carbon (BC) contents and TOC stable carbon isotope ratios (δ13C). By combining these data with 210Pb dating, an improved carbon correction model and a two end-member mixing model, we reconstructed century-scale high-resolution sequences of corrected TOC, terrestrial TOC and marine TOC contents and identified two carbon depletion events in the DH5-1 record. The two events, shown as two minima in the TOC profiles, correspond temporally to 1985-1987 AD and 2003-2006 AD, which exactly matches the water impoundment of the Gezhouba Dam and Three Gorges Dam, respectively. In addition, the variations in TOC contents and δ13C values before, during or after the minima demonstrate a relationship between the depletion events and water impoundment of the dams on the Changjiang River. The TOC reductions may represent synchronous responses of sedimentary TOC and resultant ecological effects on the inner shelf of the East China Sea to the water impoundment of the dams. These new TOC records reflect the interaction between natural and anthropogenic processes and, accordingly, provide a deep insight and important references for assessing marine ecological effects resulting from water impoundment of largescale dams.

SEDIMENTATION AND BASIN-FILL HISTORY OF THE PLIOCENE SUCCESSION EXPOSED IN THE NORTHERN SIENA-RADICOFANI BASIN (TUSCANY, ITALY: A SEQUENCE-STRATIGRAPHIC APPROACH

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IVAN MARTINI

2017-08-01

Full Text Available Basin-margin paralic deposits are sensitive indicators of relative sea-level changes and typically show complex stratigraphic architectures that only a facies-based sequence-stratigraphic approach, supported by detailed biostratigraphic data, can help unravel, thus providing constraints for the tectono-stratigraphic reconstructions of ancient basins. This paper presents a detailed facies analysis of Pliocene strata exposed in a marginal key-area of the northern Siena-Radicofani Basin (Tuscany, Italy, which is used as a ground for a new sequence-stratigraphic scheme of the studied area. The study reveals a more complex sedimentary history than that inferred from the recent geological maps produced as part of the Regional Cartographic Project (CARG, which are based on lithostratigraphic principles. Specifically, four sequences (S1 to S4, in upward stratigraphic order have been recognised, each bounded by erosional unconformities and deposited within the Zanclean-early Gelasian time span. Each sequence typically comprises fluvial to open marine facies, with deposits of different sequences that show striking lithological similarities.The architecture and internal variability shown by the studied depositional sequences are typical of low-accommodation basin-margin settings, that shows: i a poorly-developed to missing record of the falling-stage systems tract; ii a lowstand system tract predominantly made of fluvio-deltaic deposits; iii a highstand system tract with substantial thickness variation between different sequences due to erosional processes associated with the overlying unconformity; iv a highly variable transgressive system tract, ranging from elementary to parasequential organization.

Sedimentary organic matter variations in the Chukchi Borderland over the last 155 kyr

Science.gov (United States)

Rella, S. F.; Uchida, M.

2011-03-01

Knowledge on past variability of sedimentary organic carbon in the Arctic Ocean is important to assess natural carbon cycling and transport processes related to global climate changes. However, the late Pleistocene oceanographic history of the Arctic is still poorly understood. In the present study we show sedimentary records of total organic carbon (TOC), C/N and CaCO3 from a piston core recovered from the northern Northwind Ridge in the far western Arctic Ocean, a region potentially sensitively responding to past variability in surface current regimes and sedimentary processes such as coastal erosion. An age model based on correlation of our CaCO3 record with the benthic δ18O stack, supplemented by lithological constraints, suggests that the piston core records paleoenvironmental changes of the last 155 kyr. According to this age model, TOC and C/N show orbital-scale increases and decreases that can be respectively correlated to the waxing and waning of large ice sheets dominating the Eurasian Arctic, suggesting advection of fine suspended matter derived from glacial erosion to the Northwind Ridge by eastward flowing intermediate water and/or surface water and sea ice during cold episodes of the last two glacial-interglacial cycles. At millennial scales, increases in TOC and C/N appear to correlate to a suite of Dansgaard-Oeschger Stadials between 120 and 40 ka before present (BP) and thus seem to respond to abrupt northern hemispheric temperature changes. Between 65 and 40 ka BP, closures and openings of the Bering Strait could have additionally influenced TOC and C/N variability. CaCO3 content tends to anti-correlate with TOC and C/N on both orbital and millennial time scales, which we interpret as enhanced sediment advection from the carbonate-rich Canadian Arctic via an extended Beaufort Gyre during warm periods of the last two glacial-interglacial cycles and increased terrestrial organic carbon advection from the Siberian Arctic during cold periods when the

OSL, TL and IRSL emission spectra of sedimentary quartz and feldspar samples

International Nuclear Information System (INIS)

Lomax, Johanna; Mittelstraß, Dirk; Kreutzer, Sebastian; Fuchs, Markus

2015-01-01

This contribution presents a variety of different luminescence emission spectra from sedimentary feldspar and quartz samples under various stimulation modes. These are green stimulated quartz (OSL-) spectra, quartz TL spectra, feldspar IRSL and post-IR IRSL spectra. A focus was set at recording OSL and IRSL spectra at elevated stimulation temperatures such as routinely applied in luminescence dating. This was to test whether optical stimulation at elevated temperatures results in a shift of emission peaks. For OSL emissions of quartz, this has so far not been tested. In case of feldspar emissions, post-IR IRSL conditions, hence IRSL emissions at a low temperature, directly followed by high temperature post-IRSL emissions, are explicitly investigated. All spectra were recorded using a new system incorporated into a Lexsyg luminescence reader. Thus, this study, besides presenting new spectral data, also serves as a feasibility study for this new device. It is shown that (a) the new device is capable of automatically measuring different sorts of spectra, also at elevated temperatures, (b) known thermally and optically stimulated peak emissions of quartz and feldspar are confirmed, (c) obtained IRSL and OSL spectra indicate that there is no significant relation between peak emission and stimulation temperature. - Highlights: • We have measured OSL, IRSL and TL emission spectra of sedimentary quartz and feldspar samples. • Spectral analyses were performed at elevated stimulation temperatures. • Emission spectra show very little variation with stimulation temperatures.

Relationships between stratigraphy, deformation and thermal history in sedimentary basins. Impact of geodynamic concepts in petroleum exploration

International Nuclear Information System (INIS)

Sarmiento, Luis Fernando

2002-01-01

The natural processes that generate petroleum accumulations in a sedimentary basin require several ingredients: (1) the petroleum system elements: source, reservoir, seal and overburden rocks, which are the result of sedimentation processes in a subsiding basin; (2) petroleum traps, which in many cases are the result of deformation and (3) heat to convert suitable organic matter into petroleum. Although these different phenomena are considered independent at the scale of an oil field, at the lithosphere scale thermal phenomena, (2) vertical movements of the earth surface responsible for sedimentation and erosion and (3) tectonic deformation are not independent phenomena, physical quantitative laws intimately relate them. These mutual inter relationships are useful in petroleum exploration to predict one factor having knowledge of the others. Applications of these concepts can contribute to understand the tectonic history of complex areas, such as the Colombian sedimentary basins and reduce exploration risk

Dissolved particulate and sedimentary humic acids in the mangroves and estuarine ecosystem of Goa, west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Sardessai, S.

Highest concentration of humic acids in all the three forms (dissolved, particulate and sedimentary) was found in the monsoon (June-September) when the salinity was minimum while the lowest concentrations was observed in the premonsoon (February...

The role of the sedimentary regime in shaping the distribution of subtidal sandbank environments and the associated meiofaunal nematode communities: an example from the southern North Sea.

Directory of Open Access Journals (Sweden)

Michaela Schratzberger

Full Text Available We combined sediment and faunal data to explore the role of the sedimentary regime in shaping the distribution of subtidal sandbank environments and the associated meiofaunal nematode communities at Broken Bank and Swarte Bank, in the southern North Sea. A variety of sediment transport processes occur in the area, differing in the frequency and magnitude of sediment mobility, and the continuum between erosion, translation and sediment accumulation. The seabed contained a variety of bedforms, including longitudinal furrows, and small to very large sandwaves. The bed sediments were dominated by fine and medium sands, with admixtures of silt and gravel. Based on sedimentary bedforms and grain size analysis, a total of 11 sedimentary facies were delineated, of which 8 were analysed in detail for their relationships with the meiofauna. The sedimentary facies fell clearly into groups of facies, respectively representing high, high-moderate and moderate, and episodic sediment mobility. For those sedimentary facies where daily movement of sediments and bedforms occurred ('high' sediment mobility, the resulting spatially homogeneous environments were dominated by an impoverished nematode community comprising small deposit feeders and large predators. Resistance to sediment movement and the ability to exploit alternative food sources were prominent functional features of the successful colonisers. Those facies characterised by relatively infrequent sediment mobility ('episodic' and 'high-moderate and moderate' sediment mobility comprised a heterogeneous suite of benthic habitats, containing taxonomically and functionally diverse assemblages of nematodes of various sizes, feeding types and reproductive potential. Faunal distribution patterns here indicated trade-offs between the resistance to sediment movement, environmental tolerance and competitive abilities. Our focus on diverse assemblages of organisms with high turnover times, inhabiting highly

The Role of the Sedimentary Regime in Shaping the Distribution of Subtidal Sandbank Environments and the Associated Meiofaunal Nematode Communities: An Example from the Southern North Sea

Science.gov (United States)

Schratzberger, Michaela; Larcombe, Piers

2014-01-01

We combined sediment and faunal data to explore the role of the sedimentary regime in shaping the distribution of subtidal sandbank environments and the associated meiofaunal nematode communities at Broken Bank and Swarte Bank, in the southern North Sea. A variety of sediment transport processes occur in the area, differing in the frequency and magnitude of sediment mobility, and the continuum between erosion, translation and sediment accumulation. The seabed contained a variety of bedforms, including longitudinal furrows, and small to very large sandwaves. The bed sediments were dominated by fine and medium sands, with admixtures of silt and gravel. Based on sedimentary bedforms and grain size analysis, a total of 11 sedimentary facies were delineated, of which 8 were analysed in detail for their relationships with the meiofauna. The sedimentary facies fell clearly into groups of facies, respectively representing high, high-moderate and moderate, and episodic sediment mobility. For those sedimentary facies where daily movement of sediments and bedforms occurred (‘high’ sediment mobility), the resulting spatially homogeneous environments were dominated by an impoverished nematode community comprising small deposit feeders and large predators. Resistance to sediment movement and the ability to exploit alternative food sources were prominent functional features of the successful colonisers. Those facies characterised by relatively infrequent sediment mobility (‘episodic’ and ‘high-moderate and moderate’ sediment mobility) comprised a heterogeneous suite of benthic habitats, containing taxonomically and functionally diverse assemblages of nematodes of various sizes, feeding types and reproductive potential. Faunal distribution patterns here indicated trade-offs between the resistance to sediment movement, environmental tolerance and competitive abilities. Our focus on diverse assemblages of organisms with high turnover times, inhabiting highly dynamic

Facies analysis and sequence stratigraphy of neoproterozoic Platform deposits in Adrar of Mauritania, Taoudeni basin, West Africa

Science.gov (United States)

Benan, C. A. A.; Deynoux, M.

The Neoproterozoic and Palaeozoic Taoudeni basin forms the flat-lying and unmetamorphosed sedimentary cover of the West African Craton. In the western part of this basin, the Char Group and the lower part of the Atar Group make up a 400-m-thick Neoproterozoic siliciclastic succession which rests on the Palaeoproterozoic metamorphic and granitic basement. Five erosional bounding surfaces of regional extent have been identified in this succession. These surfaces separate five stratigraphic units with lithofacies associations ranging from fluvial to coastal and fluvial-, tide-, or wave-dominated shallow marine deposits. Owing to their regional extent and their position within the succession, the erosive bounding surfaces correspond to relative sea-level falls, and accordingly the five stratigraphic units they bound represent allocyclic transgressive-regressive depositional sequences (S1-S5). Changes in the nature of the deposits forming the transgressive-regressive cycles reflect landward or seaward shifts of the stacked sequences. These successive relative sea-level changes are related to the reactivation of basement faults and tilting during rifting of the Pan-Afro-Brasiliano supercontinent 1000 m.y. ago. The stromatolite bearing carbonate-shale sequences which form the rest of the Atar Group mark the onset of a quiet period of homogeneous subsidence contemporaneous with the Pan-African I oceanization 800-700 m.y. ago.

Influence of stress on the permeability of coal and sedimentary rocks of the Upper Silesian Basin

Czech Academy of Sciences Publication Activity Database

Konečný, Pavel; Kožušníková, Alena

2011-01-01

Roč. 48, č. 2 (2011), s. 347-352 ISSN 1365-1609 Institutional research plan: CEZ:AV0Z30860518 Keywords : permeability * triaxial test * coal and sedimentary rocks Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 1.272, year: 2011 http://www.sciencedirect.com/science/article/pii/S1365160910002194

SedMob: A mobile application for creating sedimentary logs in the field

Science.gov (United States)

Wolniewicz, Pawel

2014-05-01

SedMob is an open-source, mobile software package for creating sedimentary logs, targeted for use in tablets and smartphones. The user can create an unlimited number of logs, save data from each bed in the log as well as export and synchronize the data with a remote server. SedMob is designed as a mobile interface to SedLog: a free multiplatform package for drawing graphic logs that runs on PC computers. Data entered into SedMob are saved in the CSV file format, fully compatible with SedLog.

Sedimentary fabrics of the macrotidal, mud-dominated, inner estuary to fluvio-tidal transition zone, Petitcodiac River estuary, New Brunswick, Canada

Science.gov (United States)

Shchepetkina, Alina; Gingras, Murray K.; Zonneveld, John-Paul; Pemberton, S. George

2016-03-01

The study provides a detailed description of mud-dominated sedimentary fabrics and their application for the rock record within the inner estuary to the fluvial zone of the Petitcodiac River estuary, New Brunswick, Canada. Sedimentological characteristics and facies distributions of the clay- and silt-rich deposits are reported. The inner estuary is characterized by thick accumulations of interbedded silt and silty clay on intertidal banks that flank the tidally influenced channel. The most common sedimentary structures observed are parallel and wavy lamination, small-scale soft-sediment deformation with microfaults, and clay and silt current ripples. The tidal channel contains sandy silt and clayey silt with planar lamination, massive and convolute bedding. The fluvio-tidal transition zone is represented by interbedded trough cross-stratified sand and gravel beds with planar laminated to massive silty mud. The riverine, non-tidal reach of the estuary is characterized by massive, planar tabular and trough cross-stratified gravel-bed deposits. The absence of bioturbation within the inner estuary to the fluvio-tidal transition zone can be explained by the following factors: low water salinities (0-5 ppt), amplified tide and current speeds, and high concentrations of flocculated material in the water body. Notably, downstream in the middle and outer estuary, bioturbation is seasonally pervasive: in those locales the sedimentary conditions are similar, but salinity is higher. In this study, the sedimentological (i.e., grain size, bedding characters, sedimentary structures) differences between the tidal estuary and the fluvial setting are substantial, and those changes occur over only a few hundred meters. This suggests that the widely used concept of an extensive fluvio-tidal transition zone and its depositional character may not be a geographically significant component of fluvial or estuary deposits, which can go unnoticed in the study of the ancient rocks.

Paleoenvironmental reconstruction and evolution of an Upper Cretaceous lacustrine-fluvial-deltaic sequence in the Parecis Basin, Brazil

Science.gov (United States)

Rubert, Rogerio R.; Mizusaki, Ana Maria Pimentel; Martinelli, Agustín G.; Urban, Camile

2017-12-01

The Cretaceous in the Brazilian Platform records events of magmatism, tectonism and sedimentation coupled to the Gondwana breakup. Some of these events are registered as sedimentary sequences in interior basins, such as in the Cretaceous sequence of the Alto Xingu Sub-basin, Parecis Basin, Central Brazil. This article proposes the faciologic characterization and paleoenvironmental reconstruction of the Cretaceous sequence of the eastern portion of the Parecis Basin and its relation with some reactivated structures as, for instance, the Serra Formosa Arch. Based on both data from outcrops and core drillings a paleoenvironmental and evolutionary reconstruction of the sequence is herein presented. The base of the studied section is characterized by chemical and low energy clastic sedimentation of Lake Bottom and Shoreline, in a context of fast initial subsidence and low sedimentation rate. As the subsidence process decreased, a deltaic progradation became dominant with deposition in a prodelta environment, followed by a deltaic front and deltaic plain interbedded with fluvial plain, and aeolian deposition completing the sequence. The inferred Coniacian-Santonian age is based on vertebrate (fishes and notosuchians) and ostracod fossils with regional chrono-correlates in the Adamantina (Bauru Group), Capacete (Sanfranciscana Basin), and Bajo de la Carpa (Neuquén Group, in Argentina) formations. The formation of a Coniacian depocenter in the Alto Xingu Sub-basin is associated to the Turonian-Coniacian reactivation event in the Peruvian Orogenic Phase of the Andean Orogeny, with the transference of stresses to interplate setting, reactivating Proterozoic structures of the basement.

Advancements in exploration and In-Situ Recovery of sedimentary hosted uranium

International Nuclear Information System (INIS)

Märten, H.; Marsland-Smith, A.; Ross, J.; Haschke, M.; Kalka, H.; Schubert, J.

2014-01-01

This paper describes recent advancements in exploration technologies for sedimentary-hosted uranium deposits as basis for improved model-based planning and optimization of in-situ recovery (ISR). High-resolution shallow (<500 m depth) seismic in combination with refraction tomography is used for high-fidelity imaging of true-depth stratigraphy of sedimentary formations, tectonic faults and specific structures for the improved understanding of (hydro)geology in general and as potential indicator for uranium mineralization in particular. A new-generation geophysical downhole-wireline tool with pulsed neutron generator has been developed (i) to accurately measure U grade (PFN [prompt fission neutron] method with important intool corrections for systematic influences), (ii) to determine geophysical parameters including porosity, density, macroscopic neutron cross section (clay content) and deduced permeability, and (iii) to log the mineral composition (based on element-specific gamma ray spectroscopy applied to natural gamma rays as well as gamma rays from inelastic neutron scattering, thermal-neutron capture and neutron activation) – all by one tool. This new data - together with conventional geophysical and geochemical information – provides an excellent aid to the assessment of ISR feasibility, the design of wellfields and planning of wellfield operation. A new kinetic leaching model (reactive transport) has been specifically adjusted to acidic leaching conditions considering kinetic rates of the main neutralizing and redox reactions as function of both pH and oxidation potential (balance of e- acceptor species). It is used as an effective tool for predicting wellfield recovery curves, estimating chemicals’ consumption and optimizing leaching chemistry (i.e. dosage of chemicals to injection lixiviant) in dependence on mineralogical conditions (abundance of main reactants). (author)

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

Science.gov (United States)

Edgar, Lauren; Gupta, Sanjeev; Rubin, David M.; Lewis, Kevin W.; Kocurek, Gary A.; Anderson, Ryan; Bell, James F.; Dromart, Gilles; Edgett, Kenneth S.; Grotzinger, John P.; Hardgrove, Craig; Kah, Linda C.; LeVeille, Richard A.; Malin, Michael C.; Mangold, Nicholas; Milliken, Ralph E.; Minitti, Michelle; Palucis, Marisa C.; Rice, Melissa; Rowland, Scott K.; Schieber, Juergen; Stack, Kathryn M.; Sumner, Dawn Y.; Wiens, Roger C.; Williams, Rebecca M.E.; Williams, Amy J.

2018-01-01

This paper characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time, and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture, and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification to determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution, and bedform migration direction, this study concludes that the Shaler outcrop likely records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the northeast, across the surface of a bar that migrated southeast. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggests that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry, and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.

Sedimentary and mineral dust sources of dissolved iron to the world ocean

Directory of Open Access Journals (Sweden)

J. K. Moore

2008-05-01

from sinking particles; and 3 an improved sedimentary source for dissolved iron. Most scavenged iron (90% is put on sinking particles to remineralize deeper in the water column. The model-observation differences are reduced with these modifications. The improved BEC model is used to examine the relative contributions of mineral dust and marine sediments in driving dissolved-iron distributions and marine biogeochemistry. Mineral dust and sedimentary sources of iron contribute roughly equally, on average, to dissolved iron concentrations. The sedimentary source from the continental margins has a strong impact on open-ocean iron concentrations, particularly in the North Pacific. Plumes of elevated dissolved-iron concentrations develop at depth in the Southern Ocean, extending from source regions in the SW Atlantic and around New Zealand. The lower particle flux and weaker scavenging in the Southern Ocean allows the continental iron source to be advected far from sources. Both the margin sediment and mineral dust Fe sources substantially influence global-scale primary production, export production, and nitrogen fixation, with a stronger role for the dust source. Ocean biogeochemical models that do not include the sedimentary source for dissolved iron, will overestimate the impact of dust deposition variations on the marine carbon cycle. Available iron observations place some strong constraints on ocean biogeochemical models. Model results should be evaluated against both surface and subsurface Fe observations in the waters that supply dissolved iron to the euphotic zone.

Determination of Cenozoic sedimentary structures using integrated geophysical surveys: A case study in the Barkol Basin, Xinjiang, China

Science.gov (United States)

Sun, Kai; Chen, Chao; Du, Jinsong; Wang, Limin; Lei, Binhua

2018-01-01

Thickness estimation of sedimentary basin is a complex geological problem, especially in an orogenic environment. Intense and multiple tectonic movements and climate changes result in inhomogeneity of sedimentary layers and basement configurations, which making sedimentary structure modelling difficult. In this study, integrated geophysical methods, including gravity, magnetotelluric (MT) sounding and electrical resistivity tomography (ERT), were used to estimate basement relief to understand the geological structure and evolution of the eastern Barkol Basin in China. This basin formed with the uplift of the eastern Tianshan during the Cenozoic. Gravity anomaly map revealed the framework of the entire area, and ERT as well as MT sections reflected the geoelectric features of the Cenozoic two-layer distribution. Therefore, gravity data, constrained by MT, ERT and boreholes, were utilized to estimate the spatial distribution of the Quaternary layer. The gravity effect of the Quaternary layer related to the Tertiary layer was later subtracted to obtain the residual anomaly for inversion. For the Tertiary layer, the study area was divided into several parts because of lateral difference of density contrasts. Gravity data were interpreted to determine the density contrast constrained by the MT results. The basement relief can be verified by geological investigation, including the uplift process and regional tectonic setting. The agreement between geophysical survey and prior information from geology emphasizes the importance of integrated geophysical survey as a complementary means of geological studies in this region.

Sedimentary Processes. Quantification Using Radionuclides

International Nuclear Information System (INIS)

Carroll, J.; Lerche, I.

2003-01-01

The advent of radionuclide methods in geochronology has revolutionized our understanding of modern sedimentary processes in aquatic systems. This book examines the principles of the method and its use as a quantitative tool in marine geology, with emphasis on the Pb-210 method. The assumptions and consequences of models and their behaviour are described providing the necessary background to assess the advantages and trade-offs involved when choosing a particular model for application. One of the purposes of this volume is to disentangle the influences of complicating factors, such as sediment flux variations, post-depositional diffusion of radionuclides, and bio-irrigation of sediments, to arrive at sediment ages and to properly assess the attendant data uncertainty. Environmental impacts of chemical, nuclear, or other waste material are of concern in a variety of areas around the world today. A number of relevant examples are included, demonstrating how dating models are useful for determining sources of contaminants and interpreting their influence on the environment. The book is set at a level so that an able student or professional should have no difficulty in following the procedures and methods developed. Each chapter includes case histories showing the strengths and weaknesses of a given procedure with respect to a data example. Included with this volume is the computer source code of a new generation of modelling tools based on inverse numerical analysis techniques. This first generation of the modelling tool is included, along with detailed instructions and examples for its use, in an appendix

A review of the geology and major economic mineral provinces of Southern Africa

International Nuclear Information System (INIS)

Van Biljon, W.J.

1982-01-01

The sequences that are considered to contain the oldest rocks (3500 Ma), the greenstone belts, are surrounded and intruded by granitic rocks. Within these granitic terranes, ages of up to 3800 Ma have been obtained. These formations together constitute the basement complex in Southern Africa. Deposits of gold, antimony, copper, lead, zinc, and tin are found in these rocks. Around 2000 Ma ago in the Bushveld Complex with its enormous deposits of chromium, platinum, and vanadium was intruded into the sedimentary sequences in the central Transvaal. Overlying the Namaqualand gneisses, volcano-sedimentary sequences were deposited in South West Africa/Namibia. These sequences were deformed and metamorphosed some 500 to 700 Ma ago along the Damara Belt. Deposits of copper, lead, zinc, vanadium, and tin, as well as a large uranium deposit, exist within this belt. Around 500 Ma ago, sedimentary rocks were deposited in a sea along the southern edge of the present continent. These rocks were deformed into the Cape Fold Belt. Further north, the above-mentioned rocks were followed by the sedimentary and volcanic rocks of the Karoo Sequence, which contain not only all the major coal deposits of Southern Africa, but also deposits of uranium and fireclay

The structure and stratigraphy of the sedimentary succession in the Swedish sector of the Baltic Basin: New insights from vintage 2D marine seismic data

Science.gov (United States)

Sopher, Daniel; Erlström, Mikael; Bell, Nicholas; Juhlin, Christopher

2016-04-01

We present five interpreted regional seismic profiles, describing the full sedimentary sequence across the Swedish sector of the Baltic Sea. The data for the study are part of an extensive and largely unpublished 2D seismic dataset acquired between 1970 and 1990 by the Swedish Oil Prospecting Company (OPAB). The Baltic Basin is an intracratonic basin located in northern Europe. Most of the Swedish sector of the basin constitutes the NW flank of a broad synclinal depression, the Baltic Basin. In the SW of the Swedish sector lies the Hanö Bay Basin, formed by subsidence associated with inversion of the Tornquist Zone during the Late Cretaceous. The geological history presented here is broadly consistent with previously published works. We observe an area between the Hanö Bay and the Baltic Basin where the Palaeozoic strata has been affected by transpression and subsequent inversion, associated with the Tornquist Zone during the late Carboniferous-Early Permian and Late Cretaceous, respectively. We propose that the Christiansø High was a structural low during the Late Jurassic, which was later inverted in the Late Cretaceous. We suggest that a fan shaped feature in the seismic data, adjacent to the Christiansø Fault within the Hanö Bay Basin, represents rapidly deposited, coarse-grained sediments eroded from the inverted Christiansø High during the Late Cretaceous. We identify a number of faults within the deeper part of the Baltic Basin, which we also interpret to be transpressional in nature, formed during the Caledonian Orogeny in the Late Silurian-Early Devonian. East of Gotland a number of sedimentary structures consisting of Silurian carbonate reefs and Ordovician carbonate mounds, as well as a large Quaternary glacial feature are observed. Finally, we use the seismic interpretation to infer the structural and stratigraphic history of the Baltic and Hanö Bay basins within the Swedish sector.

Porous media of the Red River Formation, Williston Basin, North Dakota: a possible Sedimentary Enhanced Geothermal System

Science.gov (United States)

Hartig, Caitlin M.

2018-01-01

Fracture-stimulated enhanced geothermal systems (EGS) can be developed in both crystalline rocks and sedimentary basins. The Red River Formation (Ordovician) is a viable site for development of a sedimentary EGS (SEGS) because the formation temperatures exceed 140 °C and the permeability is 0.1-38 mD; fracture stimulation can be utilized to improve permeability. The spatial variations of the properties of the Red River Formation were analyzed across the study area in order to understand the distribution of subsurface formation temperatures. Maps of the properties of the Red River Formation-including depth to the top of the formation, depth to the bottom of the formation, porosity, geothermal gradient, heat flow, and temperature-were produced by the Kriging interpolation method in ArcGIS. In the future, these results may be utilized to create a reservoir simulation model of an SEGS in the Red River Formation; the purpose of this model would be to ascertain the thermal response of the reservoir to fracture stimulation.

Impacts of bottom and suspended cultures of mussels Mytilus spp. on the surrounding sedimentary environment and macrobenthic biodiversity

NARCIS (Netherlands)

Ysebaert, T.; Hart, M.; Herman, P.M.J.

2009-01-01

The aim of this study was to quantify the effect of bottom and suspended mussel cultures, cultured in different physical environments, on the sedimentary environmental conditions and thereby the biodiversity structure of the associated macrofaunal community. We compared two bottom cultures

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars

OpenAIRE

Ewing, R. C.; Lapotre, M. G. A.; Lewis, K. W.; Day, M.; Stein, N.; Rubin, D. M.; Sullivan, R.; Banham, S.; Lamb, M. P.; Bridges, N. T.; Gupta, S.; Fischer, W. W.

2017-01-01

The Mars Science Laboratory rover Curiosity visited two active wind-blown sand dunes within Gale crater, Mars, which provided the first ground-based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial-like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples were pre...

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars

OpenAIRE

Ewing, R. C.; Lapotre, M. G. A.; Lewis, K. W.; Day, M.; Stein, N.; Rubin, D. M.; Sullivan, R.; Banham, S.; Lamb, M. P.; Bridges, N. T.; Gupta, S.; Fischer, W. W.

2017-01-01

Abstract The Mars Science Laboratory rover Curiosity visited two active wind‐blown sand dunes within Gale crater, Mars, which provided the first ground‐based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial‐like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples...

Isotopic (U-Pb, Nd) and geochemical constraints on the origins of the Aileu and Gondwana sequences of Timor

Science.gov (United States)

Boger, S. D.; Spelbrink, L. G.; Lee, R. I.; Sandiford, M.; Maas, R.; Woodhead, J. D.

2017-02-01

Detrital zircon U-Pb age data collected from the argillitic sedimentary rocks of the Timorese Aileu Complex and Gondwana Sequence indicate that both units were derived from a common source containing 200-600 Ma, 900-1250 Ma and 1450-1900 Ma zircon. The modally most significant age population within this range of ages dates to c. 260 Ma. The observed spectrum of ages can be traced to the eastern active margin of Pangaea and its immediate foreland, which today is best exposed along the northeast coast of Australia. Compared to the relative homogeneity of the detrital zircon age data, geochemical and Nd isotopic data show that the mudstones of the Aileu Complex are on average more siliceous, have higher K2O/Na2O, Rb/Sr, Th/Sc and yield notably older Nd TDM model ages when compared to those from the Gondwana Sequence. These data are interpreted to suggest that, although both sequences share a common east Pangaea provenance, they were eroded from different sections of this active margin and deposited in spatially separated basins. The present proximity of these units is a result of their tectonic juxtaposition during the Pliocene to Recent collision between the northern edge of the Indo-Australia plate and the Banda Arc.

Characterizing flow pathways in a sandstone aquifer: Tectonic vs sedimentary heterogeneities

Science.gov (United States)

Medici, G.; West, L. J.; Mountney, N. P.

2016-11-01

Sandstone aquifers are commonly assumed to represent porous media characterized by a permeable matrix. However, such aquifers may be heavy fractured when rock properties and timing of deformation favour brittle failure and crack opening. In many aquifer types, fractures associated with faults, bedding planes and stratabound joints represent preferential pathways for fluids and contaminants. In this paper, well test and outcrop-scale studies reveal how strongly lithified siliciclastic rocks may be entirely dominated by fracture flow at shallow depths (≤ 180 m), similar to limestone and crystalline aquifers. However, sedimentary heterogeneities can primarily control fluid flow where fracture apertures are reduced by overburden pressures or mineral infills at greater depths. The Triassic St Bees Sandstone Formation (UK) of the East Irish Sea Basin represents an optimum example for study of the influence of both sedimentary and tectonic aquifer heterogeneities in a strongly lithified sandstone aquifer-type. This fluvial sedimentary succession accumulated in rapidly subsiding basins, which typically favours preservation of complete depositional cycles including fine grained layers (mudstone and silty sandstone) interbedded in sandstone fluvial channels. Additionally, vertical joints in the St Bees Sandstone Formation form a pervasive stratabound system whereby joints terminate at bedding discontinuities. Additionally, normal faults are present through the succession showing particular development of open-fractures. Here, the shallow aquifer (depth ≤ 180 m) was characterized using hydro-geophysics. Fluid temperature, conductivity and flow-velocity logs record inflows and outflows from normal faults, as well as from pervasive bed-parallel fractures. Quantitative flow logging analyses in boreholes that cut fault planes indicate that zones of fault-related open fractures characterize 50% of water flow. The remaining flow component is dominated by bed-parallel fractures

Redox front formation in an uplifting sedimentary rock sequence: An analogue for redox-controlling processes in the geosphere around deep geological repositories for radioactive waste

International Nuclear Information System (INIS)

Yoshida, H.; Metcalfe, R.; Yamamoto, K.; Murakami, Y.; Hoshii, D.; Kanekiyo, A.; Naganuma, T.; Hayashi, T.

2008-01-01

Subsurface redox fronts control the mobilization and fixation of many trace elements, including potential pollutants such as certain radionuclides. Any safety assessment for a deep geological repository for radioactive wastes needs to take into account adequately the long-term redox processes in the geosphere surrounding the repository. To build confidence in understanding these processes, a redox front in a reduced siliceous sedimentary rock distributed in an uplifting area in Japan has been studied in detail. Geochemical analyses show increased concentrations of Fe and trace elements, including rare earth elements (REEs), at the redox front, even though concentrations of reduced rock matrix constituents show little change. Detailed SEM observations revealed that fossilized microorganisms composed of amorphous granules made exclusively of Fe and Si occur in the rock's pore space. Microbial 16S rDNA analysis suggests that there is presently a zonation of different bacterial groups within the redox band, and bacterial zonation played an important role in the concentration of Fe-oxyhydroxides at the redox front. These water-rock-microbe interactions can be considered analogous to the processes occurring in the redox fronts that would develop around geological repositories for radioactive waste. Once formed, the Fe-oxyhydroxides within such a front would be preserved even after reducing conditions resume following repository closure

Redox front formation in an uplifting sedimentary rock sequence: An analogue for redox-controlling processes in the geosphere around deep geological repositories for radioactive waste

Energy Technology Data Exchange (ETDEWEB)

Yoshida, H. [Nagoya University Museum, Material Research Section, Furocho, Nagoya 464-8602 (Japan)], E-mail: dora@num.nagoya-u.ac.jp; Metcalfe, R. [Quintessa Japan, Queen' s Tower A7-707, Minatomirai, Yokohama 220-6007 (Japan); Yamamoto, K. [Nagoya University Museum, Material Research Section, Furocho, Nagoya 464-8602 (Japan); Murakami, Y. [Japan Atomic Energy Agency (JAEA), Tono Geoscience Centre (Japan); Hoshii, D.; Kanekiyo, A.; Naganuma, T. [Hiroshima University, Higashi Hiroshima, Kagamiyama 1-4-4 (Japan); Hayashi, T. [Asahi University, Department of Dental Pharmacology, Hozumi, Gifu (Japan)

2008-08-15

Subsurface redox fronts control the mobilization and fixation of many trace elements, including potential pollutants such as certain radionuclides. Any safety assessment for a deep geological repository for radioactive wastes needs to take into account adequately the long-term redox processes in the geosphere surrounding the repository. To build confidence in understanding these processes, a redox front in a reduced siliceous sedimentary rock distributed in an uplifting area in Japan has been studied in detail. Geochemical analyses show increased concentrations of Fe and trace elements, including rare earth elements (REEs), at the redox front, even though concentrations of reduced rock matrix constituents show little change. Detailed SEM observations revealed that fossilized microorganisms composed of amorphous granules made exclusively of Fe and Si occur in the rock's pore space. Microbial 16S rDNA analysis suggests that there is presently a zonation of different bacterial groups within the redox band, and bacterial zonation played an important role in the concentration of Fe-oxyhydroxides at the redox front. These water-rock-microbe interactions can be considered analogous to the processes occurring in the redox fronts that would develop around geological repositories for radioactive waste. Once formed, the Fe-oxyhydroxides within such a front would be preserved even after reducing conditions resume following repository closure.

Morphology and modern sedimentary deposits of the macrotidal Marapanim Estuary (Amazon, Brazil)

Science.gov (United States)

Araújo da Silva, Cléa; Souza-Filho, Pedro Walfir M.; Rodrigues, Suzan W. P.

2009-03-01

The northern Brazilian coast, east of the Amazon River is characterized by several macrotidal estuarine systems that harbor large mangrove areas with approximately 7600 km 2. The Marapanim Estuary is influenced by macrotidal regime with moderate waves influence. Morphologic units were investigated by using remote sensing images (i.e., Landsat-7 ETM+, RADARSAT- 1 Wide and SRTM) integrated with bathymetric data. The modern sedimentary deposits were analyzed from 67 cores collected by Vibracore and Rammkersonde systems. Analysis of morphology and surface sedimentary deposits of the Marapanim River reveal they are strongly influenced by the interaction of tidal, wave and fluvial currents. Based on these processes it was possible to recognize three distinct longitudinal facies zonation that revels the geological filling of a macrotidal estuary. The estuary mouth contain fine to medium marine sands strongly influenced by waves and tides, responsible for macrotidal sandy beaches and estuarine channel development, which are characterized by wave-ripple bedding and longitudinal cross-bedding sands. The estuary funnel is mainly influenced by tides that form wide tidal mudflats, colonized by mangroves, along the estuarine margin, with parallel laminations, lenticular bedding, root fragments and organic matter lenses. The upstream estuary contains coarse sand to gravel of fluvial origin. Massive mud with organic matter lenses, marks and roots fragments occur in the floodplain accumulates during seasonal flooding providing a slowly aggrading in the alluvial plain. This morphologic and depositional pattern show easily a tripartite zonation of a macrotidal estuary, that are in the final stage of filling.

Off-platform Silurian sequences in the Ambler River quadrangle: A section in Geologic studies in Alaska by the U.S. Geological Survey during 1987

Science.gov (United States)

Dumoulin, Julie A.; Harris, Anita G.

1988-01-01

Lithofacies changes in coeval upper Paleozoic rocks have been used to unravel the tectonic history of northern Alaska (for example, Mayfield and others, 1983). Conodont biostratigraphy and detailed petrologic studies are now revealing facies differences in lower Paleozoic rocks that can also be used to constrain their tectono-sedimentary framework (Dumoulin and Harris, 1987). A basic element of basin analysis is the discrimination of shallow-water shelf and platform sequences from deeper water slope and basinal deposits. This report documents several new localities of deeper water, off-platform Silurian deposits in the Ambler River quadrangle and briefly outlines some of their paleogeographic implications.

Whole-rock U-Pb dating of the Shuijingtuo formation sedimentary rocks in the Yangtze Gorge

International Nuclear Information System (INIS)

Zheng, Y.F.; Huang, B.

1990-01-01

Black shale and enclosed limestone lenticule from Lower Cambrian Shuijingtuo Formation in the Yangtze Gorge is successfully dated by whole-rock U-Pb method. The results yield a concordant age of about 573±14 Ma, in excellent agreement with both stratigraphic and palaeontologic evidence. The whole-rock U-Pb method can provide a reliable approach for age determination of sedimentary stratum. (orig.) [de

Across the Gap: Geochronological and Sedimentological Analyses from the Late Pleistocene-Holocene Sequence of Goda Buticha, Southeastern Ethiopia

Science.gov (United States)

Asrat, Asfawossen; Bahain, Jean-Jacques; Chapon, Cécile; Douville, Eric; Fragnol, Carole; Hernandez, Marion; Hovers, Erella; Leplongeon, Alice; Martin, Loïc; Pleurdeau, David; Pearson, Osbjorn; Puaud, Simon; Assefa, Zelalem

2017-01-01

Goda Buticha is a cave site near Dire Dawa in southeastern Ethiopia that contains an archaeological sequence sampling the late Pleistocene and Holocene of the region. The sedimentary sequence displays complex cultural, chronological and sedimentological histories that seem incongruent with one another. A first set of radiocarbon ages suggested a long sedimentological gap from the end of Marine Isotopic Stage (MIS) 3 to the mid-Holocene. Macroscopic observations suggest that the main sedimentological change does not coincide with the chronostratigraphic hiatus. The cultural sequence shows technological continuity with a late persistence of artifacts that are usually attributed to the Middle Stone Age into the younger parts of the stratigraphic sequence, yet become increasingly associated with lithic artifacts typically related to the Later Stone Age. While not a unique case, this combination of features is unusual in the Horn of Africa. In order to evaluate the possible implications of these observations, sedimentological analyses combined with optically stimulated luminescence (OSL) were conducted. The OSL data now extend the radiocarbon chronology up to 63 ± 7 ka; they also confirm the existence of the chronological gap between 24.8 ± 2.6 ka and 7.5 ± 0.3 ka. The sedimentological analyses suggest that the origin and mode of deposition were largely similar throughout the whole sequence, although the anthropic and faunal activities increased in the younger levels. Regional climatic records are used to support the sedimentological observations and interpretations. We discuss the implications of the sedimentological and dating analyses for understanding cultural processes in the region. PMID:28125597

A hybrid method for the estimation of ground motion in sedimentary basins: Quantitative modelling for Mexico City

International Nuclear Information System (INIS)

Faeh, D.; Suhadolc, P.; Mueller, S.; Panza, G.F.

1994-04-01

To estimate the ground motion in two-dimensional, laterally heterogeneous, anelastic media, a hybrid technique has been developed which combines modal summation and the finite difference method. In the calculation of the local wavefield due to a seismic event, both for small and large epicentral distances, it is possible to take into account the sources, path and local soil effects. As practical application we have simulated the ground motion in Mexico City caused by the Michoacan earthquake of September 19, 1985. By studying the one-dimensional response of the two sedimentary layers present in Mexico City, it is possible to explain the difference in amplitudes observed between records for receivers inside and outside the lake-bed zone. These simple models show that the sedimentary cover produces the concentration of high-frequency waves (0.2-0.5 Hz) on the horizontal components of motion. The large amplitude coda of ground motion observed inside the lake-bed zone, and the spectral ratios between signals observed inside and outside the lake-bed zone, can only be explained by two-dimensional models of the sedimentary basin. In such models, the ground motion is mainly controlled by the response of the uppermost clay layer. The synthetic signals explain the major characteristics (relative amplitudes, spectral ratios, and frequency content) of the observed ground motion. The large amplitude coda of the ground motion observed in the lake-bed zone can be explained as resonance effects and the excitation of local surface waves in the laterally heterogeneous clay layer. Also, for the 1985 Michoacan event, the energy contributions of the three subevents are important to explain the observed durations. (author). 39 refs, 15 figs, 1 tab

Mechanisms for Fe(III) oxide reduction in sedimentary environments

Science.gov (United States)

Nevin, Kelly P.; Lovely, Derek R.

2002-01-01

Although it was previously considered that Fe(III)-reducing microorganisms must come into direct contact with Fe(III) oxides in order to reduce them, recent studies have suggested that electron-shuttling compounds and/or Fe(III) chelators, either naturally present or produced by the Fe(III)-reducing microorganisms themselves, may alleviate the need for the Fe(III) reducers to establish direct contact with Fe(III) oxides. Studies with Shewanella alga strain BrY and Fe(III) oxides sequestered within microporous beads demonstrated for the first time that this organism releases a compound(s) that permits electron transfer to Fe(III) oxides which the organism cannot directly contact. Furthermore, as much as 450 w M dissolved Fe(III) was detected in cultures of S. alga growing in Fe(III) oxide medium, suggesting that this organism releases compounds that can solublize Fe(III) from Fe(III) oxide. These results contrast with previous studies, which demonstrated that Geobacter metallireducens does not produce electron-shuttles or Fe(III) chelators. Some freshwater aquatic sediments and groundwaters contained compounds, which could act as electron shuttles by accepting electrons from G. metallireducens and then transferring the electrons to Fe(III). However, other samples lacked significant electron-shuttling capacity. Spectroscopic studies indicated that the electron-shuttling capacity of the waters was not only associated with the presence of humic substances, but water extracts of walnut, oak, and maple leaves contained electron-shuttling compounds did not appear to be humic substances. Porewater from a freshwater aquatic sediment and groundwater from a petroleum-contaminated aquifer contained dissolved Fe(III) (4-16 w M), suggesting that soluble Fe(III) may be available as an electron acceptor in some sedimentary environments. These results demonstrate that in order to accurately model the mechanisms for Fe(III) reduction in sedimentary environments it will be necessary

Relating sedimentary processes in the Bagnold Dunes to the development of crater basin aeolian stratification

Science.gov (United States)

Ewing, R. C.; Lapotre, M. G. A.; Lewis, K. W.; Day, M. D.; Stein, N.; Rubin, D. M.; Sullivan, R. J., Jr.; Banham, S.; Thomas, N. M.; Lamb, M. P.; Gupta, S.; Fischer, W. W.

2017-12-01

Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under martian conditions. Exploration of the Bagnold Dunes by the Curiosity Rover in Gale Crater, Mars provided the first opportunity to make in situ observations of martian dunes from the grain-to-dune scale. We used the suite of cameras on Curiosity, including Navigation Camera, Mast Camera, and Mars Hand Lens Imager. We measured grainsize and identified sedimentary processes similar to processes on terrestrial dunes, such as grainfall, grainflow, and impact ripples. Impact ripple grainsize had a median of 0.103 mm. Measurements of grainflow slopes indicate a relaxation angle of 29° and grainfall slopes indicate critical angles of at least 32°. Dissimilar to terrestrial dunes, large, meter-scale ripples form on all slopes of the dunes. The ripples form both sinuous and linear crestlines, have symmetric and asymmetric profiles, range in height between 12cm and 28cm, and host grainfall, grainflow, and impact ripples. The largest ripples are interpreted to integrate the annual wind cycle within the crater, whereas smaller large ripples and impact ripples form or reorient to shorter term wind cycling. Assessment of sedimentary processes in combination with dune type across the Bagnold Dunes shows that dune-field pattern development in response to a complex crater-basin wind regime dictates the distribution of geomorphic processes. From a stratigraphic perspective, zones of highest potential accumulation correlate with zones of wind convergence, which produce complex winds and dune field patterns thereby

Diatom-based characterization of iberian coastal environments at different time scales

OpenAIRE

Ferreira, Tânia Maria de Azevedo, 1978-

2014-01-01

Tese de doutoramento, Geologia (Geologia Económica e do Ambiente), Universidade de Lisboa, Faculdade de Ciências, 2014 This thesis presents the mesoscale characterization of the evolution of two lagoon systems, Traba (550 years of sedimentary sequence) and Melides (1745 years of sedimentary sequence), using sedimentological, geochemical and biological, particularly diatoms, indicators. Also, a characterization of 18 present-day transitional environments (coastal lakes and ponds...

Sc, Y, La-Lu. Rare earth elements. Vol. A 6a. Y, La, and the lanthanoids. Geochemistry: Sedimentary cycle. Metamorphic cycle. 8. rev. ed

Energy Technology Data Exchange (ETDEWEB)

Ditz, R; Sarbas, B; Schubert, P; Toepper, W

1988-01-01

The present volume 'Rare Earth Elements' A 6a describes origin, mode of occurrence, and behavior of Y and RE elements in the sedimentary and metamorphic cycles, and completes the series of volumes describing cosmo- and geochemistry of these elements. In the chapter 'Sedimentary Cycle', the behavior of Y and RE during the weathering process is first outlined under both marine and terrestrial conditions, including a short compilation for migration and precipitation in surficial weathering and oxidation zones. The main part of the chapter treats, in addition to the mode of occurrence, predominantly the distribution of Y and RE in the different types of sedimentary rocks in relation to genetic processes (comprising physical and/or spatial factors such as geological age of the deposition). A concluding part gives a description of mobilization, migration, and precipitation of Y and RE during the diagenetic transformation of sediments, especially in relation to the various types of ferromanganese concretions. In the chapter 'Metamorphic Cycle', the first, extensive part gives examples of mode of occurrence and behavior of Y and RE during both the contact-metamorphic and prograde and retrograde regional-metamorphic processes affecting sedimentary and igeneous source rocks. The second part briefly describes behaviour of Y and RE during ultrametamorphism of metamorphic rocks, and during metamorphic processes in connection with special types of geologic events (as, e.g., subduction of crustal material into the earth's mantle and impact of extraterrestrial material). (orig.) With 4 figs.

Revisiting the effects of hydrodynamic sorting and sedimentary recycling on chemical weathering indices

Science.gov (United States)

Guo, Yulong; Yang, Shouye; Su, Ni; Li, Chao; Yin, Ping; Wang, Zhongbo

2018-04-01

Although the proxies based on elemental geochemistry of siliciclastic sediments have been well developed to indicate the intensity of chemical weathering in various catchments, their geological indications and limitations, and especially how the differentiation of minerals and sediment grain size influences the applications of these proxies needs more clarification. This paper investigates the interactive effects of weathering, hydraulic sorting and sedimentary recycling on river sediment chemistry, and further validates the application of various weathering indices by measuring mineralogical and geochemical compositions of bank sediments and suspended particulate matters (SPMs) from five rivers in East China bearing various sizes, geologic settings and climatic regimes. For a specific river, the silicate weathering intensity registered in the fine SPMs is systematically stronger than that in the coarse-grained bank sediments. Most of the weathering indices not only reflect the integrated weathering history of various catchments but also depend on hydraulic sorting effect during sediment transport and depositional processes. The correlation between CIA (chemical index of alteration) and WIP (weathering index of Parker) offers an approach to predict the weathering trends of the fine SPMs, coarse bank sediments and recycled sediments under the influence of quartz dilution. To minimize the effects of hydrodynamic sorting and sedimentary recycling, we suggest that the fine sediments (e.g. SPMs and <2 μm fraction of bank sediments) in rivers can better reflect the average of present-day weathering crust in catchments and the weathered terrigenous materials into marginal seas and oceans.

Testing Urey's carbonate-silicate cycle using the calcium isotopic composition of sedimentary carbonates

Science.gov (United States)

Blättler, Clara L.; Higgins, John A.

2017-12-01

Carbonate minerals constitute a major component of the sedimentary geological record and an archive of a fraction of the carbon and calcium cycled through the Earth's surface reservoirs for over three billion years. For calcium, carbonate minerals constitute the ultimate sink for almost all calcium liberated during continental and submarine weathering of silicate minerals. This study presents >500 stable isotope ratios of calcium in Precambrian carbonate sediments, both limestones and dolomites, in an attempt to characterize the isotope mass balance of the sedimentary carbonate reservoir through time. The mean of the dataset is indistinguishable from estimates of the calcium isotope ratio of bulk silicate Earth, consistent with the Urey cycle being the dominant mechanism exchanging calcium among surface reservoirs. The variability in bulk sediment calcium isotope ratios within each geological unit does not reflect changes in the global calcium cycle, but rather highlights the importance of local mineralogical and/or diagenetic effects in the carbonate record. This dataset demonstrates the potential for calcium isotope ratios to help assess these local effects, such as the former presence of aragonite, even in rocks with a history of neomorphism and recrystallization. Additionally, 29 calcium isotope measurements are presented from ODP (Ocean Drilling Program) Site 801 that contribute to the characterization of altered oceanic crust as an additional sink for calcium, and whose distinct isotopic signature places a limit on the importance of this subduction flux over Earth history.

Sedimentary uranium deposits in France and French Union

International Nuclear Information System (INIS)

Kervella, F.

1958-01-01

The author gives the actual state of our knowledge on uranium deposits found in recent years. Till now in precambrian formations only one important deposit has been found, at Mounana (Gabon) in a series of conglomeratic sandstones belonging to the 'Francevillien'. The observed mineralization is of the uranium-vanadium type. To the carboniferous formations corresponds in France a series of deposits, among which the most important ones are located at Saint-Hippolyte. Uranium as carburans, organic-bound complexes, is contained in lacustrine schists of Westphalian or lower Stephanian formations. A number of occurrences are also known in permo-triassic formations, particularly in the Vanoise Alps, in the Maritime Alps and in the Herault, where important occurrences have recently been found not far from Lodeve. The cretaceous and tertiary systems contain uranium deposits in phosphate rocks (Morocco, Senegal, Togo, Middle-Congo). Two sedimentary oligocene deposits are known in France. Lastly, the Vinaninkarena deposit in Madagascar, known for a long time, is the only important one reported in the quaternary series. (author) [fr

Preliminary integration study of Precambrian with tectonic events in Brazilian sedimentary basins (Republication); Estudo preliminar de integracao do Pre-Cambriano com os eventos tectonicos das bacias sedimentares brasileiras (Republicacao)

Energy Technology Data Exchange (ETDEWEB)

Cordani, Umberto G.; Neves, Benjamim B. Brito; Fuck, Reinhard A.; Porto, Roberto; Thomaz Filho, Antonio; Cunha, Francisco M. Bezerra da

2008-11-15

The various successive episodes of vertical cratogenic evolution modelling the geo tectonic features of the basement were correlated with the internal structure, shape, origin and geologic evolution of the sedimentary basin. A systematic petrologic and geochronological investigation of all available drill core samples was carried out, and the pertinent geophysical data regarding basement structure were taken into consideration. Specific geo tectonic analyses, were carried out along the borders of the sedimentary basins, within the adjacent basement. The main boundaries between Precambrian tectonic provinces, the main tectonic sutures with polycyclic evolution, and the ancient intracratonic rifts were identified wherever possible. Their extensions under the sedimentary basins were inferred, corroboration being sought from structural information and data obtained from the drill core samples. It was found that many of the identified basement discontinuities had a direct influence on the depositional history of each of the sedimentary basins, demonstrating the distinct tectonic inheritance. The subject was treated on a reconnaissance scale, 1:1.000.000 or smaller,owing to its complexity. (author)

Coastal lagoons and beach ridges as complementary sedimentary archives for the reconstruction of Holocene relative sea-level changes

DEFF Research Database (Denmark)

Sander, Lasse; Hede, Mikkel Ulfeldt; Fruergaard, Mikkel

2016-01-01

Coastal lagoons and beach ridges are genetically independent, though non-continuous, sedimentary archives. We here combine the results from two recently published studies in order to produce an 8000-year-long record of Holocene relative sea-level changes on the island of Samsø, southern Kattegat,...

Monitoring of high temperature area by resistivity tomography during in-situ heating test in sedimentary soft rocks

International Nuclear Information System (INIS)

Kubota, Kenji; Suzuki, Koichi; Ikenoya, Takafumi; Takakura, Nozomu; Tani, Kazuo

2009-01-01

One of the major issues in disposal of nuclear waste is that the long term behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperature, mechanical conditions or hydraulic conditions. Therefore, it is necessary to develop a method for evaluating the long term stability of caverns in sedimentary soft rocks as subjected to changes of environment. We have conducted in-situ heating test to evaluate the influence of high temperature to the surrounding rock mass at a depth of 50 m. The well with a diameter of 30 cm and 60 cm of height, was drilled and filled with groundwater. The heater was installed in the well for heating the surrounding rock mass. During the heating, temperature and deformation around the well were measured. To evaluate the influence of heating on sedimentary soft rocks, it is important to monitor the extent of heated area. Resistivity monitoring is thought to be effective to map the extent of the high temperature area. So we have conducted resistivity tomography during the heating test. The results demonstrated that the resistivity of the rock mass around the heating well decreased and this area was gradually expanded from the heated area during the heating. The decreasing rate of resistivity on temperature is correlated to that of laboratory experimental result and existing empirical formula between aqueous solution resistivity and temperature. Resistivity is changed by many other factors, but it is expected that resistivity change by other factors is very few in this test. This suggests that high temperature area is detected and spatial distribution of temperature can be mapped by resistivity tomography. So resistivity tomography is expected to be one of the promising methods to monitor the area heated by nuclear waste. (author)

Luminescence chronology of loess-paleosol sequences from Canterbury, South Island, New Zealand

International Nuclear Information System (INIS)

Berger, G.W.; Pillans, B.J.; Tonkin, P.J.

2001-01-01

results illustrate some of the problems for luminescence dating of such sequences in South Island, they do provide a beginning for a more accurate correlation of terrestrial and terrestrial-marine sedimentary sequences in this part of the Southern Hemisphere. (author). 81 refs., 10 figs., 3 tabs

Faults in Paleozoic basement and their participation in Alpine deformation of Greater Caucasus – evidences from materials of restored (balanced) sections in folded sedimentary cover

Science.gov (United States)

Yakovlev, Fedor

2015-04-01

Method. As each fold has information about strain, numerous folds (0.1-1 km width) inside of hinterland (stripe about 1000 x 50 km) of Greater Caucasus (GC) allow to restore structure for whole sedimentary cover. Material of 24 detailed sections of 510 km total actual length in three regions was used for restoration of structure. These sections were split on 505 domains as associations of 2-5 folds. Three parameters of morphology were measured in these domains: dip of axial plain, dip of envelope plain, value of shortening as interlimb angle [1, 2, 3]. Because these parameters correlate with ellipsoid (ellipse) of strain for domain, sequence of three kinematic operations allow to restore actual state of domain to pre-folded state (from ellipse to circle): rotation to horizontal position of envelope plain, horizontal simple shear to vertical axial plain and vertical flattening (pure shear). Aggregation of chain of pre-folded domains is forming a pre-folded state of whole section, and it allows to calculate of shortening value. For correct detailing of strain study, 78 "structural cells" were formed by aggregation of 5-10 domains in each cell. Some additional observations and calculations allow to find initial and post-folded thickness of sedimentary cover, depth of cover bottom, virtual position of cover top (amplitude of erosion) for all tectonic cells. The received result for 78 cells allowed to understand the main features of GC structure, to see a distribution of basement top depth, to give behavior pattern of the basement and to find a role of faults in shortening of the basement and of sedimentary cover. Results. Three regions of GC were studied: North-Western Caucasus (NWC) [1], Chiaur tectonic zone in South Ossetia (ChZ) and two zones in South-Eastern Caucasus - Tfan Zone (TZ) and Shakhdag zone (ShZ) [3]. The shortening values for structural cells were found as 49% in average for ShZ (with deviations 37÷62%), 55% for TZ (36÷67%), 57% for ChZ (46÷67%) and

The Orosirian-Statherian banded iron formation-bearing sequences of the southern border of the Espinhaço Range, Southeast Brazil

Science.gov (United States)

Rolim, Vassily Khoury; Rosière, Carlos A.; Santos, João Orestes Schneider; McNaughton, Neal J.

2016-01-01

The Serra da Serpentina and the Serra de São José groups are two distinct banded iron formation-bearing metasedimentary sequences along the eastern border of the southern Espinhaço Range that were deposited on the boundary between the Orosirian and Statherian periods. The Serra da Serpentina Group (SSG) has an Orosirian maximum depositional age (youngest detrital zircon grain age = 1990 ± 16 Ma) and consists of fine clastic metasediments at the base and chemical sediments, including banded iron formations (BIFs), on the top, corresponding to the Meloso and Serra do Sapo formations, respectively, and correlating with the pre-Espinhaço Costa Sena Group. The SSG represents sedimentary deposition on an epicontinental-epeiric, slow downwarping sag basin with little tectonic activity. The younger Serra de São José Group (SJG) is separated from the older SSG by an erosional unconformity and was deposited in a tectonically active continental rift-basin in the early stages of the opening of the Espinhaço Trough. The Serra do São José sediments stretch along the north-south axis of the rift and comprise a complete cycle of transgressive sedimentary deposits, which were subdivided, from base to top, into the Lapão, Itapanhoacanga, Jacém and Canjica formations. The Itapanhoacanga Formation has a maximum depositional age of 1666 ± 32 Ma (Statherian), which coincides with the maximum depositional age (i.e., 1683 ± 11 Ma) of the São João da Chapada Formation, one of the Espinhaço Supergroup's basal units. The Serra de São José Rift and the Espinhaço Rift likely represent the same system, with basal units that are facies variations of the same sequence. The supracrustal rocks have undergone two stages of deformation during the west-verging Brasiliano orogeny that affected the eastern margin of the São Francisco Craton and generated a regional-scale, foreland N-S trending fold-thrust belt, which partially involved the crystalline basement. Thrust faults have

Characterizing the hypersiliceous rocks of Belgium used in (pre-)history: a case study on sourcing sedimentary quartzites

International Nuclear Information System (INIS)

Veldeman, Isis; Baele, Jean-Marc; De Doncker, H W J A; Goemaere, Eric; Deceukelaire, Marleen; Dusar, Michiel

2012-01-01

Tracking raw material back to its extraction source is a crucial step for archaeologists when trying to deduce migration patterns and trade contacts in (pre-)history. Regarding stone artefacts, the main rock types encountered in the archaeological record of Belgium are hypersiliceous rocks. This is a newly introduced category of rock types comprising those rocks made of at least 90% silica. These are strongly silicified quartz sands or sedimentary quartzites, siliceous rocks of chemical and biochemical origin (e.g. flint), very pure metamorphic quartzites and siliceous volcanic rocks (e.g. obsidian). To be able to distinguish between different extraction sources, ongoing research was started to locate possible extraction sources of hypersiliceous rocks and to characterize rocks collected from these sources. Characterization of these hypersiliceous rocks is executed with the aid of optical polarizing microscopy, optical cold cathodoluminescence and scanning-electron microscopy combined with energy-dispersive x-ray spectrometry and with back-scatter electron imaging. In this paper, we focus on various sedimentary quartzites of Paleogene stratigraphical level. (paper)

Extensional Tectonics and Sedimentary Architecture Using 3-D Seismic Data: An Example from Hydrocarbon-Bearing Mumbai Offshore Basin, West Coast of India

Science.gov (United States)

Mukhopadhyay, D. K.; Bhowmick, P. K.; Mishra, P.

2016-12-01

In offshore sedimentary basins, analysis of 3-D seismic data tied with well log data can be used to deduce robust isopach and structure contour maps of different stratigraphic formations. The isopach maps give depocenters whereas structure contour maps give structural relief at a specific time. Combination of these two types of data helps us decipher horst-graben structures, sedimentary basin architecture and tectono-stratigraphic relations through Tertiary time. Restoration of structural cross sections with back-stripping of successively older stratigraphic layers leads to better understand tectono-sedimentary evolution of a basin. The Mumbai (or Bombay) Offshore Basin is the largest basin off the west coast of India and includes Bombay High giant oil/gas field. Although this field was discovered in 1974 and still producing, the basin architecture vis-à-vis structural evolution are not well documented. We take the approach briefly outlined above to study in detail three large hydrocarbon-bearing structures located within the offshore basin. The Cretaceous Deccan basalt forms the basement and hosts prodigal thickness (> 8 km at some localities) of Tertiary sedimentary formations.A two stage deformation is envisaged. At the first stage horst and graben structures formed due to approximately E-W extensional tectonics. This is most spectacularly seen at the basement top level. The faults associated with this extension strike NNW. At the second stage of deformation a set of ENE-striking cross faults have developed leading to the formation of transpressional structures at places. High rate of early sedimentation obliterated horst-graben architecture to large extent. An interesting aspect emerges is that the all the large-scale structures have rather low structural relief. However, the areal extent of such structures are very large. Consequently, these structures hold commercial quantities of oil/gas.

Geochronology of sedimentary and metasedimentary Precambrian rocks of the West African craton

International Nuclear Information System (INIS)

Clauer, N.; Jeannette, D.; Trompette, R.

1982-01-01

This contribution summarizes current knowledge of the geochronology of the Upper Proterozoic sedimentary rocks covering the West African craton. This was done by using direct dating methods. Correlations between the northern edge of the Tindouf basin and the northern and southern part of the Taoudeni basin, as well as the Volta basin, are proposed. Tectonic, volcanic and thermal activities in connection with the Pan-African orogeny are recorded only around the craton. They induced either sedimentation lacks in Morocco or sedimentation excesses in Hoggar. Unsolved problems such as the precise stratigraphic position of the uppermost Proterozoic tillitic episode and the correlation within the Moroccan Anti-Atlas are also raised. (Auth.)

Northeast Guanabara Bay and coastal plain Holocene sedimentary evolution (Brazil: A contribution

Directory of Open Access Journals (Sweden)

Rodrigo Coutinho Abuchacra

2017-02-01

Full Text Available Sedimentological and radiocarbon investigations are part of an ongoing research on the Bay-head delta of northeast Guanabara Bay, Rio de Janeiro State. Sediment accumulation indicates that the Holocene infill of the bay-head delta started around 8.2 kyr BP and was not in pace with the eustatic sea-level rise. Sediment accumulation was faster during the transgressive phase (0.56 cm.yr-1. However, during the regressive phase, progradation driven by base-level fall was predominant over vertical sediment accumulation (0.02 cm.yr-1. Based on coring, three sedimentary units were defined: fluvial sands (U1, estuarine deposits (U2 and fluvial mud (U3.

Triaxial slide-hold-slide shear experiment of sedimentary rock under drain condition

International Nuclear Information System (INIS)

Kishida, Kiyoshi; Yano, Takao; Elsworth, Derek; Yasuhara, Hideaki; Nakashima, Shinichiro

2011-01-01

When discussing the mechanical and hydro-mechanical properties of rock masses under the long-term holding, the variation of rock structure and the change of shear band condition should be discussed in considering the effect of thermal and chemical influences. In this research, the triaxial shear experiment under drain condition was conducted through sedimentary rock, and in the residual stress state, the slide-hold-slide processes were applied to these triaxial experiments. The experiments were carried out in 3 kinds of confining conditions and 2 kinds of thermal conditions. Consequently, the healing phenomena can be observed and the shear strength recovery is also confirmed in process of the holding time. (author)

Sedimentary rhythms in coastal dunes as a record of intra-annual changes in wind climate (Łeba, Poland)

Science.gov (United States)

Ludwig, J.; Lindhorst, S.; Betzler, C.; Bierstedt, S. E.; Borówka, R. K.

2017-08-01

It is shown that coastal dunes bear a so far unread archive of annual wind intensity. Active dunes at the Polish coast near Łeba consist of two genetic units: primary dunes with up to 18 m high eastward-dipping foresets, temporarily superimposed by smaller secondary dunes. Ground-penetrating radar (GPR) data reveal that the foresets of the primary dunes are bundled into alternating packages imaged as either low- or high-amplitude reflections. High-amplitude packages are composed of quartz sand with intercalated heavy-minerals layers. Low-amplitude packages lack these heavy-mineral concentrations. Dune net-progradation is towards the east, reflecting the prevalence of westerly winds. Winds blowing parallel to the dune crest winnow the lee slope, leaving layers enriched in heavy minerals. Sediment transport to the slip face of the dunes is enhanced during the winter months, whereas winnowing predominantly takes place during the spring to autumn months, when the wind field is bi-directional. As a consequence of this seasonal shift, the sedimentary record of one year comprises one low- and one high-amplitude GPR reflection interval. This sedimentary pattern is a persistent feature of the Łeba dunes and recognized to resemble a sedimentary "bar code". To overcome hiatuses in the bar code of individual dunes and dune-to-dune variations in bar-code quality, dendrochronological methods were adopted to compile a composite bar code from several dunes. The resulting data series shows annual variations in west-wind intensity at the southern Baltic coast for the time period 1987 to 2012. Proxy-based wind data are validated against instrumental based weather observations.

Fire history and climate variability during the Mid-Late Holocene in the Picos de Europa (Cantabrian Mountains, NW Spain), based on sedimentary sequence of Belbín

Science.gov (United States)

Ruiz-Fernández, Jesús; Nieuwendam, Alexandre; Oliva, Marc; Lopes, Vera; Cruces, Anabela; Conceição Freitas, Maria; Janeiro, Ana; López-Sáez, José Antonio; García-Hernández, Cristina

2017-04-01

The environmental changes during the last millennia in the Mediterranian Region (including the Cantabrian Mountains in the NW part of the Iberian Peninsula) are partially related to fire activity, generated by early human societies for grazing purposes. Fire activity has mostly been reconstructed based on the analysis of pollen, spores and other macro- and microscopic organic remains, such as charcoal particles. However, new techniques (as the analysis of micro-scale frost weathering of quartz grains), can provide further information about the magnitude and intensity of fire as a landscape modeler. The purpose of this work was to analyze a sedimentary sequence collected from Belbín depression in the Western Massif of the Picos de Europa (Cantabrian Mountains, NW Spain) by using an innovative multi-proxy approach, in order to reconstruct the fire history in this area. The Picos de Europa Mountains constitute the highest and most extensive massif in the Cantabrian Mountains. This area encloses three different massifs separated by deep gorges carved by four rivers (Dobra, Cares, Duje and Deva). The Western Massif is the largest of the three units (137 km2). The Picos de Europa are essentially composed by Carboniferous limestones. This mountain area was heavily glaciated during the Last Glaciation, though the post-glacial environmental evolution is still poorly understood. Within the Western Massif, the mid-altitude area of Belbín is a karstic depression dammed by a lateral moraine generated by Enol Glacier during the Last Glaciation. Between 23 and 8 ky cal BP this depression was a lake that became progressively infilled with sediments, and nowadays it is occupied by grasslands (Ruiz-Fernández et al., 2016). In order to study the environmental changes during the Mid-Late Holocene in this massif, a 182 cm-long sequence was retrieved in the Belbín area. The core was subsampled every centimeter in the top most superficial 60 cm. The laboratory analyses were: 1

The post-Laramide clastic deposits of the Sierra de Guanajuato: Compositional implications on the tectono-sedimentary and paleographic evolution

Energy Technology Data Exchange (ETDEWEB)

Miranda-Aviles, R.; Puy-Alquiza, M.J.; OmaNa, L.; Loza-Aguirre, I.

2016-07-01

This article presents the results of the study on sedimentation, sedimentary environments, tectono-sedimentary and paleogeographic evolution of post-Laramide clastic deposits and pre-volcanism of the Sierra Madre Occidental in the Sierra de Guanajuato, central Mexico. The Eocene Duarte Conglomerate and Guanajuato Conglomerate were deposited in the middle and distal parts of alluvial fans. The studied rocks are composed of limestone clasts, granite, andesite, metasediments, diorite, and pyroxenite, indicating the erosion of uplifted blocks of the basal complex of the Sierra de Guanajuato (Arperos basin). The petrographic and compositional analysis of limestone shows a textural variation from basin limestones and shallow platform limestones. The shallow platform limestone contain bivalves, brachiopods, gastropods, echinoderms and benthic foraminifera from the Berriasian-Valanginian. The shallow-water limestone corresponds to the boundary of the Arperos basin whose original outcrops currently not outcrop in the Sierra de Guanajuato. (Author)

The Alleret Maar lacustrine sequence (French Massif Central): a 150 ka long early-middle Pleistocene continental paleoenvironmental record.

Science.gov (United States)

Nomade, S.; Pastre, J.; Guillou, H.; Gauthier, A.; Scaillet, S.

2008-12-01

Lacustrine maar sequences of the French Massif Central are of great interest for paleoclimatic and paleoenvironmental reconstructions of mid-latitudes Quaternary continental environments. In particular, the western Velay region yields exceptional sequences spanning the last 450 ka (Reille et al., J. Quat. Sci. 2000). However, older sequences remain largely unknown despite the presence of interbedded alkaline tephras allowing precise absolute radiochronological control of many lacustrine squences. The Alleret maar is a 1500 m wide phreatomagmatic crater that provides a long lacustrine sequence (41 m). The upper part of this sequence (AL2 core, 14.6 m) was studied between 2005 and 2006 (Pastre et al., C. R. Acad Sci, 2007). A 39Ar/40Ar date (557 ± 5ka) obtained from an interbedded tephra layer located at 7m as well as the associated pollen data attribute the beginning of this sequence to the MIS 15. Thanks to the AL3 core recovered in 2005 (40.6 m, CNRS Meudon) several new tephra layers were discovered in the bottom part of this lacustrine sequence. Three new 39Ar/40Ar ages (single crystal analyses) from trachytic tephra layers were obtained at the LSCE Argon Laboratory (France). These layers are located at -30.2, -36.2 and -39.2m. Ages obtained relative to the ACR-2 flux standard (1,201Ma, Kuiper et al., Science, 2008) range from 692 ± 6 ka (MSWD: 2.3, n=18) for the youngest (-30.2m) to 726 ± 9Ka Ka (MSWD: 2.2, n=12) for the lowest tephra located at -39.2m. These new dates indicate a relatively homogeneous deposition rate of 3.5cm/ka and that the last 10 meters cover the MIS 17-MIS18 period. According to these current radiochronological data the complete lacustrine sequence last more than 150ka. Ongoing sedimentary and pollen studies will allow to extend the paleoenvironmental and paleoclimatic records of the French Massif Central towards the beginning of the early middle Pleistocene.

Regional geological assessment of the Devonian-Mississippian shale sequence of the Appalachian, Illinois, and Michigan basins relative to potential storage/disposal of radioactive wastes

Energy Technology Data Exchange (ETDEWEB)

Lomenick, T.F.; Gonzales, S.; Johnson, K.S.; Byerly, D.

1983-01-01

The thick and regionally extensive sequence of shales and associated clastic sedimentary rocks of Late Devonian and Early Mississippian age has been considered among the nonsalt geologies for deep subsurface containment of high-level radioactive wastes. This report examines some of the regional and basin-specific characteristics of the black and associated nonblack shales of this sequence within the Appalachian, Illinois, and Michigan basins of the north-central and eastern United States. Principal areas where the thickness and depth of this shale sequence are sufficient to warrant further evaluation are identified, but no attempt is made to identify specific storage/disposal sites. Also identified are other areas with less promise for further study because of known potential conflicts such as geologic-hydrologic factors, competing subsurface priorities involving mineral resources and groundwater, or other parameters. Data have been compiled for each basin in an effort to indicate thickness, distribution, and depth relationships for the entire shale sequence as well as individual shale units in the sequence. Included as parts of this geologic assessment are isopach, depth information, structure contour, tectonic elements, and energy-resource maps covering the three basins. Summary evaluations are given for each basin as well as an overall general evaluation of the waste storage/disposal potential of the Devonian-Mississippian shale sequence,including recommendations for future studies to more fully characterize the shale sequence for that purpose. Based on data compiled in this cursory investigation, certain rock units have reasonable promise for radioactive waste storage/disposal and do warrant additional study.

Regional geological assessment of the Devonian-Mississippian shale sequence of the Appalachian, Illinois, and Michigan basins relative to potential storage/disposal of radioactive wastes

International Nuclear Information System (INIS)

Lomenick, T.F.; Gonzales, S.; Johnson, K.S.; Byerly, D.

1983-01-01

The thick and regionally extensive sequence of shales and associated clastic sedimentary rocks of Late Devonian and Early Mississippian age has been considered among the nonsalt geologies for deep subsurface containment of high-level radioactive wastes. This report examines some of the regional and basin-specific characteristics of the black and associated nonblack shales of this sequence within the Appalachian, Illinois, and Michigan basins of the north-central and eastern United States. Principal areas where the thickness and depth of this shale sequence are sufficient to warrant further evaluation are identified, but no attempt is made to identify specific storage/disposal sites. Also identified are other areas with less promise for further study because of known potential conflicts such as geologic-hydrologic factors, competing subsurface priorities involving mineral resources and groundwater, or other parameters. Data have been compiled for each basin in an effort to indicate thickness, distribution, and depth relationships for the entire shale sequence as well as individual shale units in the sequence. Included as parts of this geologic assessment are isopach, depth information, structure contour, tectonic elements, and energy-resource maps covering the three basins. Summary evaluations are given for each basin as well as an overall general evaluation of the waste storage/disposal potential of the Devonian-Mississippian shale sequence,including recommendations for future studies to more fully characterize the shale sequence for that purpose. Based on data compiled in this cursory investigation, certain rock units have reasonable promise for radioactive waste storage/disposal and do warrant additional study

Relating Gestures and Speech: An analysis of students' conceptions about geological sedimentary processes

Science.gov (United States)

Herrera, Juan Sebastian; Riggs, Eric M.

2013-08-01

Advances in cognitive science and educational research indicate that a significant part of spatial cognition is facilitated by gesture (e.g. giving directions, or describing objects or landscape features). We aligned the analysis of gestures with conceptual metaphor theory to probe the use of mental image schemas as a source of concept representations for students' learning of sedimentary processes. A hermeneutical approach enabled us to access student meaning-making from students' verbal reports and gestures about four core geological ideas that involve sea-level change and sediment deposition. The study included 25 students from three US universities. Participants were enrolled in upper-level undergraduate courses on sedimentology and stratigraphy. We used semi-structured interviews for data collection. Our gesture coding focused on three types of gestures: deictic, iconic, and metaphoric. From analysis of video recorded interviews, we interpreted image schemas in gestures and verbal reports. Results suggested that students attempted to make more iconic and metaphoric gestures when dealing with abstract concepts, such as relative sea level, base level, and unconformities. Based on the analysis of gestures that recreated certain patterns including time, strata, and sea-level fluctuations, we reasoned that proper representational gestures may indicate completeness in conceptual understanding. We concluded that students rely on image schemas to develop ideas about complex sedimentary systems. Our research also supports the hypothesis that gestures provide an independent and non-linguistic indicator of image schemas that shape conceptual development, and also play a role in the construction and communication of complex spatial and temporal concepts in the geosciences.

Thermal infrared spectral analysis of compacted fine-grained mineral mixtures: implications for spectral interpretation of lithified sedimentary materials on Mars

Science.gov (United States)

Pan, C.; Rogers, D.

2012-12-01

Characterizing the thermal infrared (TIR) spectral mixing behavior of compacted fine-grained mineral assemblages is necessary for facilitating quantitative mineralogy of sedimentary surfaces from spectral measurements. Previous researchers have demonstrated that TIR spectra from igneous and metamorphic rocks as well as coarse-grained (>63 micron) sand mixtures combine in proportion to their volume abundance. However, the spectral mixing behavior of compacted, fine-grained mineral mixtures that would be characteristic of sedimentary depositional environments has received little attention. Here we characterize the spectral properties of pressed pellet samples of pestle and centrifuged to obtain less than 10 micron size. Pure phases and mixtures of two, three and four components were made in varying proportions by volume. All of the samples were pressed into pellets at 15000PSI to minimize volume scattering. Thermal infrared spectra of pellets were measured in the Vibrational Spectroscopy Laboratory at Stony Brook University with a Thermo Fisher Nicolet 6700 Fourier transform infrared Michelson interferometer from ~225 to 2000 cm-1. Our preliminary results indicate that some pelletized samples have contributions from volume scattering, which leads to non-linear spectral combinations. It is not clear if the transparency features (which arise from multiple surface reflections of incident photons) are due to minor clinging fines on an otherwise specular pellet surface or to partially transmitted energy through optically thin grains in the compacted mixture. Inclusion of loose powder (analysis of TES and Mini-TES data of lithified sedimentary deposits.

Recently studied sedimentary records from the eastern Arabian Sea: Implications to Holocene monsoonal variability

Digital Repository Service at National Institute of Oceanography (India)

Agnihotri, R.; Kurian, S.

stream_size 72460 stream_content_type text/plain stream_name Earth_Sci_India_1_258.pdf.txt stream_source_info Earth_Sci_India_1_258.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 Agnihotri http://www....earthscienceindia.info/Agnihotri.htm 1 of 14 10/15/2008 9:41 AM Earth Science India Vol.1 (IV), October, 2008, pp. 258-287 http://www.earthscienceindia.info/ Recently studied sedimentary records from the eastern Arabian Sea: Implications to Holocene monsoonal variability Rajesh...

Geomorphological and sedimentary processes of the glacially influenced northwestern Iberian continental margin and abyssal plains

Science.gov (United States)

Llave, Estefanía; Jané, Gloria; Maestro, Adolfo; López-Martínez, Jerónimo; Hernández-Molina, F. Javier; Mink, Sandra

2018-07-01

The offshore region of northwestern Iberia offers an opportunity to study the impacts of along-slope processes on the morphology of a glacially influenced continental margin, which has traditionally been conceptually characterised by predominant down-slope sedimentary processes. High-resolution multibeam bathymetry, acoustic backscatter and ultrahigh-resolution seismic reflection profile data are integrated and analysed to describe the present-day and recent geomorphological features and to interpret their associated sedimentary processes. Seventeen large-scale seafloor morphologies and sixteen individual echo types, interpreted as structural features (escarpments, marginal platforms and related fluid escape structures) and depositional and erosional bedforms developed either by the influence of bottom currents (moats, abraded surfaces, sediment waves, contourite drifts and ridges) or by gravitational features (gullies, canyons, slides, channel-levee complexes and submarine fans), are identified for the first time in the study area (spanning 90,000 km2 and water depths of 300 m to 5 km). Different types of slope failures and turbidity currents are mainly observed on the upper and lower slopes and along submarine canyons and deep-sea channels. The middle slope morphologies are mostly determined by the actions of bottom currents (North Atlantic Central Water, Mediterranean Outflow Water, Labrador Sea Water and North Atlantic Deep Water), which thereby define the margin morphologies and favour the reworking and deposition of sediments. The abyssal plains (Biscay and Iberian) are characterised by pelagic deposits and channel-lobe systems (the Cantabrian and Charcot), although several contourite features are also observed at the foot of the slope due to the influence of the deepest water masses (i.e., the North Atlantic Deep Water and Lower Deep Water). This work shows that the study area is the result of Mesozoic to present-day tectonics (e.g. the marginal platforms

Transfer and mobility of trace metallic elements in the sedimentary column of continental hydro-systems

International Nuclear Information System (INIS)

Devallois, V.

2009-02-01

In freshwater systems, trace metal pollutants are transferred into water and sedimentary columns under dissolved forms and/or fixed onto solid particles. Accumulated in the sedimentary areas, these latter ones can constitute important stocks of materials and associated pollutants and may impair water quality when environmental changes lead to increase their mobility. The mobility of the stocks of pollutants is mainly depending on the erosion, on the interstitial diffusion of the mobile phases (dissolved and colloidal) and on the bioturbation. In this context, this study involves the analysis of the mobility by interstitial diffusion. This topic consists in studying trace metal fractionation between their mobile (dissolved and colloidal) and non mobile (fixed onto the particles) forms. This point is governed by sorption/desorption processes at the particle surfaces. These processes are regulated by physico-chemical parameters (pH, redox potential, ionic strength...) and are influenced by biogeochemical reactions resulting from the oxidation of the organic matter by the microbial activity. These reactions generate vertical profiles of nutrients and metal concentrations along the sedimentary column. To understand these processes, this work is based on a mixed approach that combines in situ, analysis and modelling. In situ experimental part consists in sampling natural sediments cores collected at 4 different sites (1 site in Durance and 3 sites on the Rhone). These samples are analyzed according to an analytical protocol that provides the vertical distribution of physicochemical parameters (pH, redox potential, size distribution, porosity), nutrients and solid - liquid forms of trace metals (cobalt, copper, nickel, lead, zinc). The analysis and interpretation of these experimental results are based on a model that was developed during this study and that includes: 1) model of interstitial diffusion (Boudreau, 1997), 2) biogeochemical model (Wang and Van Cappellen

Sedimentary mode and reservoir genesis of dual grain banks at the Lower Cambrian Longwangmiao Fm carbonate ramp in the Sichuan Basin

Directory of Open Access Journals (Sweden)

Jinhu Du

2016-11-01

Full Text Available The gas reservoir of the Lower Cambrian Longwangmiao Fm in the Sichuan Basin is a supergiant integral marine carbonate gas reservoir whose single scale is currently the largest in China. In order to figure out its sedimentary model and reservoir genesis, its geological structures and sedimentary settings and facies were analyzed comprehensively and the lithofacies paleographic map was plotted. It is revealed that the following sedimentary facies are successively developed in the Longwangmiao Fm from West Sichuan to Southeast Chongqing: diamictic tidal flat at the back ramp, grain bank (the upper bank at the inner/shallow ramp – interbank sea (depression, deeper open bay at the platform depression of inner ramp → evaporative lagoon → evaporative tidal flat, tempestite at the middle ramp – barrier beach – mud mound beach (the lower bank, and outer ramp – basin. Accordingly, the specific sedimentary model of dual grain banks in the Longwangmiao Fm carbonate ramp was established as follows. Firstly, in this model, dual grain banks are symmetrically developed with Wanzhou–Yibin platform depression as the axis, on whose dual sides the paleohighs have shallow water bodies with strong energy. Compared with the classical model, the new one has a new upper bank which is developed around the paleohighs covering an area of about 8 × 104 km2. Secondly, the upper bank is large for its paleogeomorphology being located at the highest position with the strongest water energy during deposition. Therefore, it is prone to dolomitization and meteoric dissolution respectively during contemporaneous–penecontemporaneous hot-dry and hot-humid periods, and especially the Caledonian–Early Hercynian denudation wedge out tends to undergo post-supergene multiphase karstification. Therefore, quality reservoirs are more developed on scale. Thirdly, the intergranular pores and vermes moldic pores were dissolved and enlarged due to the multiphase

Clay, Water, and Salt: Controls on the Permeability of Fine-Grained Sedimentary Rocks.

Science.gov (United States)

Bourg, Ian C; Ajo-Franklin, Jonathan B

2017-09-19

The ability to predict the permeability of fine-grained soils, sediments, and sedimentary rocks is a fundamental challenge in the geosciences with potentially transformative implications in subsurface hydrology. In particular, fine-grained sedimentary rocks (shale, mudstone) constitute about two-thirds of the sedimentary rock mass and play important roles in three energy technologies: petroleum geology, geologic carbon sequestration, and radioactive waste management. The problem is a challenging one that requires understanding the properties of complex natural porous media on several length scales. One inherent length scale, referred to hereafter as the mesoscale, is associated with the assemblages of large grains of quartz, feldspar, and carbonates over distances of tens of micrometers. Its importance is highlighted by the existence of a threshold in the core scale mechanical properties and regional scale energy uses of shale formations at a clay content X clay ≈ 1/3, as predicted by an ideal packing model where a fine-grained clay matrix fills the gaps between the larger grains. A second important length scale, referred to hereafter as the nanoscale, is associated with the aggregation and swelling of clay particles (in particular, smectite clay minerals) over distances of tens of nanometers. Mesoscale phenomena that influence permeability are primarily mechanical and include, for example, the ability of contacts between large grains to prevent the compaction of the clay matrix. Nanoscale phenomena that influence permeability tend to be chemomechanical in nature, because they involve strong impacts of aqueous chemistry on clay swelling. The second length scale remains much less well characterized than the first, because of the inherent challenges associated with the study of strongly coupled nanoscale phenomena. Advanced models of the nanoscale properties of fine-grained media rely predominantly on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, a mean field

Geochemical Aspects of Formation of Large Oil Deposits in the Volga-Ural Sedimentary Basin

Science.gov (United States)

Plotnikova, I.; Nosova, F.; Pronin, N.; Nosova, J.; Budkevich, T.

2012-04-01

The study of the rocks domanikoid type in the territory of the Ural-Volga region has an almost century-long history, beginning with the first studies of A.D. Archangelsky in the late 20's of last century. But nevertheless the question of the source of oil that formed the industrial deposits of Volga-Ural oil and gas province (OGP), where Romashkinskoye oil field occupies a special place, remains unresolved and topical. According to the sedimentary-migration theory of origin of oil and gas, it is supposed that the primary source of hydrocarbons in this area are the deposits of domanikoid type that contain a large ammount of sapropel organic matter (OM). Semiluki (domanik) horizon of srednefranski substage of the Upper Devonian is considered to be a typical domanikoid stratum. Investigation of the OM of the rocks and oils of the sedimentary cover on the basis of chromato-mass spectrometry method allows us to study the correlations between rock and oil and to assess the location (or absence) of the sources of hydrocarbons in the Paleozoic sedimentary cover. The results of geochemical study of dispersed organic matter (DOM) of rocks from Semiluksky horizon of the Upper Devonian and of the oil from Pashiysky horizon of the Middle Devonian form the basis of this paper. The objectives of this study were the following: to determine the original organic matter of the rocks, which would indicate the conditions of sedimentation of the supposed rock-oil sources; the study of chemofossils (biomarkers) in oil from Pashiyskiy horizon; and the identification of genetic association of DOM rocks from Semiluksky horizon with this oil on the basis of the oil-DOM correlation. The study of biomarkers was carried out with the help of chromato-mass spectrometry in the Laboratory of Geochemistry of Fossil Fuels (Kazan Federal University). In this study we used several informative parameters characterizing the depositional environment, the type of source OM and its maturity: STER / PENT, h

Mesoarchean Banded Iron Formation sequences in Dixon Island-Cleaverville Formation, Pilbara Australia: Oxygenic signal from DXCL project

Science.gov (United States)

Kiyokawa, S.; Ito, T.; Ikehara, M.; Yamaguchi, K. E.; Naraoka, H.; Onoue, T.; Horie, K.; Sakamoto, R.; Aihara, Y.; Miki, T.

2013-12-01

The 3.2-3.1 Ga Dixon island-Cleaverville formations are well-preserved Banded Iron Formation (BIF) within hydrothermal oceanic sequence at oceanic island arc setting (Kiyokawa et al., 2002, 2006, 2012). The stratigraphy of the Dixon Island (3195+15Ma) -Cleaverville (3108+13Ma) formations shows the well preserved environmental condition at the Mesoarchean ocean floor. The stratigraphy of these formations are formed about volcano-sedimentary sequences with hydrothermal chert, black shale and banded iron formation to the top. Based on the scientific drilling of DXCL project at 2007 and 2011, detail lithology between BIF sequence was clearly understood. Four drilling holes had been done at coastal sites; the Dixon Island Formation is DX site (100m) and the Cleaverville Formation is CL2 (40m), CL1 (60m) and CL3 (200m) sites and from stratigraphic bottom to top. Coarsening and thickening upward black shale-BIF sequences are well preserved of the stratigraphy form the core samples. The Dixon Island Formation consists komatiite-rhyolite sequences with many hydrothermal veins and very fine laminated cherty rocks above them. The Cleaverville Formation contains black shale, fragments-bearing pyroclastic beds, white chert, greenish shale and BIF. The CL3 core, which drilled through BIF, shows siderite-chert beds above black shale identified before magnetite lamination bed. U-Pb SHRIMP data of the tuff in lower Dixon Island Formation is 3195+15 Ma and the pyroclastic sequence below the Cleaverville BIF is 3108+13 Ma. Sedimentation rate of these sequence is 2-8 cm/ 1000year. The hole section of the organic carbon rich black shales below BIF are similar amount of organic content and 13C isotope (around -30per mill). There are very weak sulfur MIF signal (less 0.2%) in these black shale sequence. Our result show that thick organic rich sediments may be triggered to form iron rich siderite and magnetite iron beds. The stratigraphy in this sequence quite resemble to other Iron

Sedimentary changes on the Southeastern Brazilian upper slope during the last 35,000 years

Directory of Open Access Journals (Sweden)

Michel M. Mahiques

2007-03-01

Full Text Available A first evaluation of the sedimentary changes, including accumulation of inorganic and organic carbon on the upper slope off Southeastern Brazil under different climatic conditions, based on the analysis of a sedimentary core, is here presented. Results indicate that sedimentation rate as well sedimentary characteristics, including the nature of the organic carbon deposited during the LGM (Last Glacial Maximum, were different from the present deposition, indicating higher primary productivity during the LGM, to be accounted for by the higher values of marine organic carbon. Nevertheless, the higher values of Accumulation Rate of calcium carbonate and organic carbon can be credited to the higher values of the sedimentation rates. Conditions prevailing during Isotope Stage 3 may be considered intermediate as between the LGM and the present day. The conditions for a higher primary productivity associated with the deposition of finer terrigenous sediments may be explained as a response to the off shoreward displacement of the main flow of the Brazil Current.Este trabalho apresenta uma primeira avaliação das mudanças sedimentares, incluindo a acumulação de carbono orgânico e inorgânico, no talude continental superior do Brasil, sob diferentes condições climáticas, baseadas em análises de um testemunho. Os resultados indicam que a taxa de sedimentação, assim como as características sedimentares, incluindo a natureza do carbono orgânico depositado durante o UMG (Último Máximo Glacial, foram diferentes dos processos deposicionais atuais, indicando maior produtividade primária durante o UMG, como determinado pelos maiores valores de carbono orgânico marinho. Entretanto, os maiores valores de Taxa de Acumulação de carbonato de cálcio e carbono orgânico podem ser creditados aos valores mais altos de taxas de sedimentação. As condições prevalentes durante o Estágio Isotópico 3 podem ser consideradas intermediárias entre o UMG e

Sedimentation and erosion processes in Middle to Late Pleistocene sequences exposed in the brickyard of Langenlois/Lower Austria

DEFF Research Database (Denmark)

Thiel, Christine; Terhorst, Birgit; Jaburová, Iva

2011-01-01

The correlation of sedimentary and pedogenetic processes in Lower Austria is difficult due to significant discontinuities and local variability in soil formation. This hampers landscape reconstruction at a regional scale. However, at a local scale distinct landscape formation processes represented...... by a shift from fluvial to aeolian deposition can be observed in the brickyard of Langenlois, Lower Austria. Sedimentological and mineralogical analyses in combination with palaeontological finds suggest that the fluvial deposition took place during the Middle Pleistocene. This attribution is confirmed...... in Austria; it indicates a Middle Pleistocene interglacial period. The low degree of weathering as well as Cryosols found in the loess sequence point to loess accumulation during the Last Glacial; the dating results (35–55 ka) indicate prolonged loess deposition. No signs of pedogenesis could be found...

Classification Scheme for Diverse Sedimentary and Igneous Rocks Encountered by MSL in Gale Crater

Science.gov (United States)

Schmidt, M. E.; Mangold, N.; Fisk, M.; Forni, O.; McLennan, S.; Ming, D. W.; Sumner, D.; Sautter, V.; Williams, A. J.; Gellert, R.

2015-01-01

The Curiosity Rover landed in a lithologically and geochemically diverse region of Mars. We present a recommended rock classification framework based on terrestrial schemes, and adapted for the imaging and analytical capabilities of MSL as well as for rock types distinctive to Mars (e.g., high Fe sediments). After interpreting rock origin from textures, i.e., sedimentary (clastic, bedded), igneous (porphyritic, glassy), or unknown, the overall classification procedure (Fig 1) involves: (1) the characterization of rock type according to grain size and texture; (2) the assignment of geochemical modifiers according to Figs 3 and 4; and if applicable, in depth study of (3) mineralogy and (4) geologic/stratigraphic context. Sedimentary rock types are assigned by measuring grains in the best available resolution image (Table 1) and classifying according to the coarsest resolvable grains as conglomerate/breccia, (coarse, medium, or fine) sandstone, silt-stone, or mudstone. If grains are not resolvable in MAHLI images, grains in the rock are assumed to be silt sized or smaller than surface dust particles. Rocks with low color contrast contrast between grains (e.g., Dismal Lakes, sol 304) are classified according to minimum size of apparent grains from surface roughness or shadows outlining apparent grains. Igneous rocks are described as intrusive or extrusive depending on crystal size and fabric. Igneous textures may be described as granular, porphyritic, phaneritic, aphyric, or glassy depending on crystal size. Further descriptors may include terms such as vesicular or cumulate textures.

Nutrient regeneration susceptibility under contrasting sedimentary conditions from the Rio de Janeiro coast, Brazil

International Nuclear Information System (INIS)

Matos, Christiene R.L.; Mendoza, Ursula; Diaz, Rut; Moreira, Manuel; Belem, Andre L.; Metzger, Edouard; Albuquerque, Ana Luiza S.

2016-01-01

Dissolved silicate (DSi), NH 4 + , NO 3 − and PO 4 3− susceptibility to be exchanged between sediment pore waters and overlying waters was evaluated in Jurujuba Sound (JS station) and Coroa Grande Sound (CGS station), southeastern Brazil. Sedimentary elemental (C, N and P) and isotopic (δ 13 C and δ 15 N) compositions evidenced stronger anthropogenic fertilization in JS station. Net NO 3 − influxes from overlying waters occurred, which was two orders of magnitude higher under the more fertilized condition. This condition resulted in 6–13-times higher net effluxes of NH 4 + , DSi and PO 4 3− to overlying waters. Vertical alternation between production and consumption processes in pore waters contributed for a more limited regeneration in CGS station. This was associated with diagenetic responses to sedimentary grain size variability in deeper layers and biological disturbance in upper layers. Nearly continuous production of NH 4 + , DSi and PO 4 3− in pore waters implied in intensified susceptibility to remobilization under the eutrophic condition of JS station. - Highlights: • SO 4 2− reduction was a driver for the larger nutrient regeneration susceptibilities. • NO 3 − reduction processes resulted in net NO 3 − influxes from overlying waters. • Effluxes (NH 4 + > DSi > PO 4 3− ) were accentuated under the more fertilized condition. • Fluxes were limited by alternations between consumption and production processes.

Spatial and seasonal contrasts of sedimentary organic matter in floodplain lakes of the central Amazon basin

OpenAIRE

Sobrinho, R. L.; Bernardes, M. C.; Abril, G.; Kim, J. H.; Zell, C. I.; Mortillaro, J. M.; Meziane, T.; Moreira Turcq, Patricia; Damste, J. S. S.

2016-01-01

In this study, we investigated the seasonal and spatial pattern of sedimentary organic matter (SOM) in five floodplain lakes of the central Amazon basin (Cabaliana, Janauaca, Canaçari, Miratuba, and Curuai) which have different morphologies, hydrodynamics and vegetation coverages. Surface sediments were collected in four hydrological seasons: low water (LW), rising water (RW), high water (HW) and falling water (FW) in 2009 and 2010. We investigated commonly used bulk geochem...

Modern sedimentary environments in a large tidal estuary, Delaware Bay

Science.gov (United States)

Knebel, H.J.

1989-01-01

Data from an extensive grid of sidescan-sonar records reveal the distribution of sedimentary environments in the large, tidally dominated Delaware Bay estuary. Bathymetric features of the estuary include large tidal channels under the relatively deep (> 10 m water depth) central part of the bay, linear sand shoals (2-8 m relief) that parallel the sides of the tidal channels, and broad, low-relief plains that form the shallow bay margins. The two sedimentary environments that were identified are characterized by either (1) bedload transport and/or erosion or (2) sediment reworking and/or deposition. Sand waves and sand ribbons, composed of medium to coarse sands, define sites of active bedload transport within the tidal channels and in gaps between the linear shoals. The sand waves have spacings that vary from 1 to 70 m, amplitudes of 2 m or less, and crestlines that are usually straight. The orientations of the sand waves and ribbons indicate that bottom sediment movement may be toward either the northwest or southeast along the trends of the tidal channels, although sand-wave asymmetry indicates that the net bottom transport is directed northwestward toward the head of the bay. Gravelly, coarse-grained sediments, which appear as strongly reflective patterns on the sonographs, are also present along the axes and flanks of the tidal channels. These coarse sediments are lag deposits that have developed primarily where older strata were eroded at the bay floor. Conversely, fine sands that compose the linear shoals and muddy sands that cover the shallow bay margins appear mainly on the sonographs either as smooth featureless beds that have uniform light to moderate shading or as mosaics of light and dark patches produced by variations in grain size. These acoustic and textural characteristics are the result of sediment deposition and reworking. Data from this study (1) support the hypothesis that bed configurations under deep tidal flows are functions of current

High-resolution sequence stratigraphic character and sandstone-type uranium ore formation. A case from Saihan Formation in Baiyinwula area, Erlian Basin

International Nuclear Information System (INIS)

He Zhongbo; Qin Mingkuan

2006-01-01

High-resolution sequence stratigraphy has been applied widely in the petroleum exploration and development, many achievements have been achieved. However, it is in the beginning stage that high-resolution sequence stratigraphy is applied to explore the sandstone-type uranium deposits in Erlian Basin. By applying principles of high-resolution sequence stratigraphy and taking typical boreholes as an example, sedimentary cycles of Saihan Formation, the ore-bearing formation in Baiyinwula area are divided and correlated through cross sections. One long-term cycle (LSC 1 ), two middle-term cycles (MSC 1 , MSC 2 ) have been identified in this study. Based on this and combined with the mineralization character of sandstone uranium deposits in this area, it is presented that the interlayer oxidation zone is developed mainly in the rising hemicycle of MSC 1 and uranium ore bodies predominantly in channel sand bodies that were developed in the system tract with low accommodation; furthermore, it is recognized that these sand bodies are moderate (10-15 m) in thickness, fairly good in interconnectivity, relatively thin (<3 m) with the argillaceous interbed, and good in permeability, abundant in the organic matter and thus it is favorable for the development of the interlayer oxidization zone. (authors)

Rb-Sr measurements on metamorphic rocks from the Barro Alto Complex, Goias, Brazil

International Nuclear Information System (INIS)

Fuck, R.A.; Neves, B.B.B.; Cordani, U.G.; Kawashita, K.

1988-01-01

The Barro Alto Complex comprises a highly deformed and metamorphosed association of plutonic, volcanic, and sedimentary rocks exposed in a 150 x 25 Km boomerang-like strip in Central Goias, Brazil. It is the southernmost tip of an extensive yet discontinuous belt of granulite and amphibolite facies metamorphic rocks which include the Niquelandia and Cana Brava complexes to the north. Two rock associations are distinguished within the granulite belt. The first one comprises a sequence of fine-grained mafic granulite, hypersthene-quartz-feldspar granulite, garnet quartzite, sillimanite-garnet-cordierite gneiss, calc-silicate rock, and magnetite-rich iron formation. The second association comprises medium-to coarse-grained mafic rocks. The medium-grade rocks of the western/northern portion (Barro Alto Complex) comprise both layered mafic rocks and a volcanic-sedimentary sequence, deformed and metamorphosed under amphibolite facies conditions. The fine-grained amphibolite form the basal part of the Juscelandia meta volcanic-sedimentary sequence. A geochronologic investigation by the Rb-Sr method has been carried out mainly on felsic rocks from the granulite belt and gneisses of the Juscelandia sequence. The analytical results for the Juscelandia sequence are presented. Isotope results for rocks from different outcrops along the gneiss layer near Juscelandia are also presented. In conclusion, Rb-Sr isotope measurements suggest that the Barro Alto rocks have undergone at least one important metamorphic event during Middle Proterozoic times, around 1300 Ma ago. During that event volcanic and sedimentary rocks of the Juscelandia sequence, as well as the underlying gabbro-anorthosite layered complex, underwent deformation and recrystallization under amphibolite facies conditions. (author)

Organic geochemistry of the Dongsheng sedimentary uranium ore deposits, China

International Nuclear Information System (INIS)

Tuo Jincai; Ma Wanyun; Zhang Mingfeng; Wang Xianbin

2007-01-01

Organic matter (OM) associated with the Dongsheng sedimentary U ore hosting sandstone/siltstone was characterized by Rock-Eval, gas chromatography-mass spectrometry and stable C isotope analysis and compared to other OM in the sandstone/siltstone interbedded organic matter-rich strata. The OM in all of the analyzed samples is Type III with Ro less than 0.6%, indicating that the OM associated with these U ore deposits can be classified as a poor hydrocarbon source potential for oil and gas. n-Alkanes in the organic-rich strata are characterized by a higher relative abundance of high-molecular-weight (HMW) homologues and are dominated by C 25 , C 27 or C 29 with distinct odd-to-even C number predominances from C 23 to C 29 . In contrast, in the sandstone/siltstone samples, the n-alkanes have a higher relative abundance of medium-molecular-weight homologues and are dominated by C 22 with no or only slight odd-to-even C number predominances from C 23 to C 29 . Methyl alkanoates in the sandstone/siltstone extracts range from C 14 to C 30 , maximizing at C 16 , with a strong even C number predominance, but in the organic-rich layers the HMW homologues are higher, maximizing at C 24 , C 26 or C 28 , also with an even predominance above C 22 . n-Alkanes in the sandstone/siltstone sequence are significantly depleted in 13 C relative to n-alkanes in most of the organic-rich strata. Diasterenes, ββ-hopanes and hopenes are present in nearly all the organic-rich sediments but in the sandstone/siltstone samples they occur as the geologically mature isomers. All the results indicate that the OM in the Dongsheng U ore body is derived from different kinds of source materials. The organic compounds in the organic-rich strata are mainly terrestrial, whereas, in the sand/siltstones, they are derived mainly from aquatic biota. Similar distribution patterns and consistent δ 13 C variations between n-alkanes and methyl alkanoates in corresponding samples suggest they are derived from

Mineralogical and geochemical characteristics of Miocene pelitic sedimentary rocks from the south-western part of the Pannonian Basin System (Croatia: Implications for provenance studies

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Anita Grizelj

2017-01-01

Full Text Available Fifty-two samples of Miocene pelitic sedimentary rock from outcrops on Medvednica, Moslavačka Gora and Psunj Mts., and boreholes in the Sava Depression and the Požega Sub-depression were investigated. These sediments formed in different marine (with normal and reduced salinity, brackish, and freshwater environments, depending on the development stage of the Pannonian Basin System. Carbonate minerals, clay minerals and quartz are the main constituents of all pelitic sedimentary rocks, except in those from Moslavačka Gora Mt in which carbonate minerals are not present. Feldspars, pyrite, opal-CT, and hematite are present as minor constituents in some rocks. Besides calcite, dependent on the sedimentary environment and diagenetic changes, high-magnesium calcite, aragonite, dolomite and ankerite/Ca-dolomite are also present. Smectite or illite-smectite is the main clay minerals in the samples. Minor constituents, present in almost all samples, are detrital illite and kaolinite. In some samples chlorite is also present in a low amount. Major elements, trace elements and rare earth elements patterns used in provenance analysis show that all analysed samples have a composition similar to the values of the upper continental crust (UCC. The contents of major and trace elements as well as SiO2/Al2O3, K2O/Al2O3, Na2O/K2O, Eu/Eu*, La/Sc, Th/Sc, La/Co Th/Co, Th/Cr, Ce/Ce* and LREE/HREE ratios, show that the analysed pelitic sedimentary rocks were formed by weathering of different types of mostly acidic (silicic, i.e. felsic rocks.

Sedimentary facies and lithologic characters as main factors controlling hydrocarbon accumulations and their critical conditions

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Jun-Qing Chen

2015-10-01

Full Text Available Taking more than 1000 clastic hydrocarbon reservoirs of Bohai Bay Basin, Tarim Basin and Junggar Basin, China as examples, the paper has studied the main controlling factors of hydrocarbon reservoirs and their critical conditions to reveal the hydrocarbon distribution and to optimize the search for favorable targets. The results indicated that the various sedimentary facies and lithologic characters control the critical conditions of hydrocarbon accumulations, which shows that hydrocarbon is distributed mainly in sedimentary facies formed under conditions of a long-lived and relatively strong hydrodynamic environment; 95% of the hydrocarbon reservoirs and reserves in the three basins is distributed in siltstones, fine sandstones, lithified gravels and pebble-bearing sandstones; moreover, the probability of discovering conventional hydrocarbon reservoirs decreases with the grain size of the clastic rock. The main reason is that the low relative porosity and permeability of fine-grained reservoirs lead to small differences in capillary force compared with surrounding rocks small and insufficiency of dynamic force for hydrocarbon accumulation; the critical condition for hydrocarbon entering reservoir is that the interfacial potential in the surrounding rock (Φn must be more than twice of that in the reservoir (Φs; the probability of hydrocarbon reservoirs distribution decreases in cases where the hydrodynamic force is too high or too low and when the rocks have too coarse or too fine grains.

BasinVis 1.0: A MATLAB®-based program for sedimentary basin subsidence analysis and visualization

Science.gov (United States)

Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

2016-06-01

Stratigraphic and structural mapping is important to understand the internal structure of sedimentary basins. Subsidence analysis provides significant insights for basin evolution. We designed a new software package to process and visualize stratigraphic setting and subsidence evolution of sedimentary basins from well data. BasinVis 1.0 is implemented in MATLAB®, a multi-paradigm numerical computing environment, and employs two numerical methods: interpolation and subsidence analysis. Five different interpolation methods (linear, natural, cubic spline, Kriging, and thin-plate spline) are provided in this program for surface modeling. The subsidence analysis consists of decompaction and backstripping techniques. BasinVis 1.0 incorporates five main processing steps; (1) setup (study area and stratigraphic units), (2) loading well data, (3) stratigraphic setting visualization, (4) subsidence parameter input, and (5) subsidence analysis and visualization. For in-depth analysis, our software provides cross-section and dip-slip fault backstripping tools. The graphical user interface guides users through the workflow and provides tools to analyze and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the results using the full range of available plot options in MATLAB. We demonstrate all functions in a case study of Miocene sediment in the central Vienna Basin.

Postclosure safety assessment of a used fuel repository in sedimentary rock

International Nuclear Information System (INIS)

Gobien, M.; Garisto, F.; Hunt, N.; Kremer, E.

2014-01-01

The Nuclear Waste Management Organization (NWMO) is responsible for the implementation of Adaptive Phased Management (APM), the federally-approved plan for safe long-term management of Canada's used nuclear fuel. Under the APM plan, used nuclear fuel will ultimately be placed within a deep geological repository in a suitable rock formation. This paper summarizes an illustrative case study of the current multi-barrier design and postclosure safety of a deep geological repository in a hypothetical sedimentary Michigan Basin setting. The purpose of this postclosure safety assessment is to determine potential effects of the repository on the health and safety of persons and the environment. Results are compared against acceptance criteria established for the protection of persons and the environment from potential radiological and non-radiological hazards. (author)

Postclosure safety assessment of a used fuel repository in sedimentary rock

Energy Technology Data Exchange (ETDEWEB)

Gobien, M.; Garisto, F.; Hunt, N.; Kremer, E. [Nuclear Waste Management Organization, Toronto, ON (Canada)

2014-07-01

The Nuclear Waste Management Organization (NWMO) is responsible for the implementation of Adaptive Phased Management (APM), the federally-approved plan for safe long-term management of Canada's used nuclear fuel. Under the APM plan, used nuclear fuel will ultimately be placed within a deep geological repository in a suitable rock formation. This paper summarizes an illustrative case study of the current multi-barrier design and postclosure safety of a deep geological repository in a hypothetical sedimentary Michigan Basin setting. The purpose of this postclosure safety assessment is to determine potential effects of the repository on the health and safety of persons and the environment. Results are compared against acceptance criteria established for the protection of persons and the environment from potential radiological and non-radiological hazards. (author)

Assessing the potential of amino acid 13C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis

Science.gov (United States)

Larsen, T.; Bach, L. T.; Salvatteci, R.; Wang, Y. V.; Andersen, N.; Ventura, M.; McCarthy, M. D.

2015-08-01

Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing the biosynthetic origin of amino acid carbon skeletons, based on naturally occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions, and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results emphasize that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e., isoleucine, lysine, leucine and tyrosine), bacterially derived amino acids ranged from 10 to 15 % in the sediment layers from the last 5000 years, and up to 35 % during the last glacial period. The greater bacterial contributions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a

Hierarchy of sedimentary discontinuity surfaces and condensed beds from the middle Paleozoic of eastern North America: Implications for cratonic sequence stratigraphy

Science.gov (United States)

McLaughlin, P.I.; Brett, Carlton E.; Wilson, M.A.

2008-01-01

Sedimentological analyses of middle Paleozoic epeiric sea successions in North America suggest a hierarchy of discontinuity surfaces and condensed beds of increasing complexity. Simple firmgrounds and hardgrounds, which are comparatively ephemeral features, form the base of the hierarchy. Composite hardgrounds, reworked concretions, authigenic mineral crusts and monomictic intraformational conglomerates indicate more complex histories. Polymictic intraformational conglomerates, ironstones and phosphorites form the most complex discontinuity surfaces and condensed beds. Complexity of discontinuities is closely linked to depositional environments duration of sediment starvation and degree of reworking which in turn show a relationship to stratigraphic cyclicity. A model of cratonic sequence stratigraphy is generated by combining data on the complexity and lateral distribution of discontinuities in the context of facies successions. Lowstand, early transgressive and late transgressive systems tracts are representative of sea-level rise. Early and late transgressive systems tracts are separated by the maximum starvation surface (typically a polymictic intraformational conglomerate or condensed phosphorite), deposited during the peak rate of sea-level rise. Conversely the maximum flooding surface, representing the highest stand of sea level, is marked by little to no break in sedimentation. The highstand and falling stage systems tracts are deposited during relative sea-level fall. They are separated by the forced-regression surface, a thin discontinuity surface or condensed bed developed during the most rapid rate of sea-level fall. The lowest stand of sea level is marked by the sequence boundary. In subaerially exposed areas it is occasionally modified as a rockground or composite hardground.

Silurian deltaic progradation, Tassili n'Ajjer plateau, south-eastern Algeria: Sedimentology, ichnology and sequence stratigraphy

Science.gov (United States)

Djouder, Hocine; Lüning, Sebastian; Da Silva, Anne-Christine; Abdallah, Hussein; Boulvain, Frédéric

2018-06-01

The economic potential for unconventional shale oil and gas production in the Silurian of the Berkine - Ghadames and Illizi basins (BGI) in south-eastern Algeria has been recently confirmed through exploration drilling. The aim of the present paper attempts a better understanding of the Intra-Tassilian depression within the entire Silurian of the Tassili n'Ajjer plateau. The continuous deposits of the Silurian are exposed at the southern margin of the prolific BGI basins, in the Tassili n'Ajjer plateau, offering the chance to understand the sedimentology, ichnology, and to present a detailed sequence stratigraphy framework for the region. The 410 m-thick clastic Silurian sedimentary strata are subdivided into three formations in the context of sequence stratigraphy, namely: (i) the Oued Imihrou Fm. (Llandoverian) overlain by (ii) the Atafaïtafa Fm. (late Llandoverian to Wenlockian), and (iii) the Oued Tifernine Fm. (late Wenlockian to Pridolian). These can be also distinguished across the entire investigated area and laterally traceable over kilometers. Clear cyclic stacking patterns are identified within the four studied sections showing progressively a general trend of thickening- and coarsening-upward, over a complete 2nd-order megasequence (SIL-1 MS). This transgressive-regressive succession suggests deltaic progradation, shallowing and basin infilling as evidenced by numerous diagnostic sedimentary features and trace fossils, largely from eastern-to western-Tassili plateau. Indeed, the wealth of outcrop data in the Silurian siliciclastic succession enables us to distinct thirteen facies (facies A-M), ranging from shallow-to marginal-marine facies, and in turn, grouped into six facies associations (FA1-FA6). The lowermost part of the succession, which is the most prolific sources of hydrocarbons in North Africa, consists of thick organic-rich graptolite-yielding black 'hot' shales and 'lean' shales with sparse bioturbation with small Thalassinoides belonging

Magmatism and sedimentation in an area in the Continental Shelf of Cabo Frio, Rio de Janeiro, Brazil, in the Upper Cretaceous - Tertiary interval; Magmatismo e sedimentacao em uma area na Plataforma Continental de Cabo Frio, Rio de Janeiro, Brasil, no intervalo Cretaceo Superior - Terciario

Energy Technology Data Exchange (ETDEWEB)

Oreiro, Sergio Goulart [PETROBRAS S.A., Santos, SP (Brazil). E e P. Ativo de Exploracao Santos - Polo Sul], E-mail: oreiro@petrobras.com.br

2005-11-15

The Continental Shelf of the Cabo Frio Area shows unique features in its tectono-sedimentary evolution when compared to the other areas of the Campos and Santos basins. The presence of a regular pattern of antithetic faults in the basement and in the sin-rift and post-rift sedimentary sections, are some of these features. In addition, the area shows important magmatic events in the Upper Cretaceous and Tertiary sequences, which climax took place in the earliest portion of the Middle Eocene. The description of these magmatic events and their influence in the post-rift sedimentation is the main objective of this paper. The analyses of seismic reflection and well log data, in the work area, points to a set of diagnostic features that can lead to the identification of magmatic events and the distinction of intrusive from extrusive rocks, as well as their intercalations with epiclastic sedimentary sequences. Volcanic edifices have preserved their conical shapes when they were formed under submarine conditions; under subaereal conditions, they show irregular shapes due to erosion. In this way, these observations indicate the paleobathymetry for the time of the formation of these edifices. In the case of the work area, the integration of the analyzed data indicates that extrusive events are more widespread than intrusive events. The sedimentary pattern of the work area is similar to that of the Campos Basin. The sedimentary sequences that overlap this volcano-sedimentary section are not directly related to the magmatic pulses in the area; however, they affected the palaeo-relief of the sea floor, which controlled turbiditic deposition. (author)

Effect of alteration processes on the distribution of radionuclides in uraniferous sedimentary rocks and their environmental impact, southwestern Sinai, Egypt

International Nuclear Information System (INIS)

El Aassy, I.E.; El Galy, M.M.; El Feky, M.G.; Ibrahim, E.M.; Nada, A.A.; Abd El Maksoud, T.M.; Talaat, S.M.

2011-01-01

The contents of natural radionuclides in various types of sedimentary rocks in Um Bogma Formation and base of El Hashash Formation were determined by gamma-ray spectrometry. Three types of lower Carboniferous sedimentary rocks were investigated; sandstone (El Hashash Formation), dolostone and argillaceous sediments (Um Bogma Formation). The alteration processes are dolomitization, dedolomitization, karstification and lateritization. The specific radioactivity of 238 U, 226 Ra, 232 Th and 40 K determined in different samples, indicate that 238 U and its decay products contribute primarily to the high natural radioactivity of rocks. The maximum concentration of 238 U reached up to 2129.36 ppm in argillaceous sediments. The average concentrations of determined radionuclides ( 238 U, 226 Ra, 232 Th and 40 K) are 8.34 ppm, 7.88 ppm, 4.68 ppm and 0.3%, respectively in sandstone. In dolostones the average concentrations are 418.69 ppm, 808.75 ppm, 3.14 ppm and 0.29%, respectively. For argillaceous sediments are 276.88 ppm, 419.49 ppm, 11.47 ppm and 0.93%, respectively. The 238 U/ 226 Ra ratio in sandstone ranges between 0.89 and 1.25, while in dolostones and argillaceous sediments are 0.27-2.63 and 0.27-1.83, respectively. These variations in the concentrations of radioelements and their ratios are due to the action of the alteration processes affected these different sedimentary rocks in different times. Environmentally, the Raeq in dolostones and argillaceous sediments exceeds the permitted limits, while in the sandstone samples; it is within the permissible levels. (author)

Facies-succession and architecture of the third-order sequences and their stratigraphic framework of the Devonian in Yunnan-Guizhou-Guangxi area, South China

Directory of Open Access Journals (Sweden)

Mei Mingxiang

2013-01-01

Full Text Available The Caledonian orogeny at the end of the Silurian resulted in great changes in the palaeogeography in the Yunnan-Guizhou-Guangxi area of South China; the continental area of the Early Paleozoic evolved into the extensive Dian-Qian-Gui Sea in the Late Paleozoic. Early in the Devonian, as a result of a major transgression, seawater encroached gradually from the south to the north and clastic facies were deposited. Carbonate deposition was then established in the Yunnan-Guizhou-Guangxi area, with a palaeogeography marked by attached platforms, isolated platforms and narrow basins. As a result of the Ziyun movement towards the end of the Devonian, the Upper Devonian strata are regressive and thin out from the open-sea to the land areas. A study of the nature and distribution of sedimentary facies in space and time recognises 13 third-order sequences in the Devonian strata in Yunnan-Guizhou-Guangxi area, and these form two second-order sequences. The strata of the Lower Devonian comprise 5 third-order sequences (SQ1 to SQ5, which are dominated by transgressive clastics. 4 third-order sequences (SQ6 to SQ9 in the Middle Devonian are characterized by alternations of transgressive clastics and highstand carbonates. In the Upper Devonian, carbonates constitute 4 third-order sequences (SQ10 to SQ13, which are generally marked by the transgressive limestones and highstand dolomites. On the basis of earlier biostratigraphic studies, sea-level changes represented by the third-order sequences with their different facies successions are explored, and the sequence stratigraphic framework is established. Therefore, the Devonian strata in the study area provide an example for further understanding of depositional trends within the sequence-stratigraphic framework.

Recent Sedimentary Processes Along the Western Continental Margin of the South Korea Plateau, East Sea of Korea

Science.gov (United States)

Cukur, D.; Um, I. K.; Bahk, J. J.; Chun, J. H.; Lee, G. S.; Soo, K. G.; Horozal, S.; Kim, S. P.

2017-12-01

The continental margins of the marginal seas is largely shaped by a complex interplay of sediment transport processes directed both downslope and along-slope. Factors influence the sediment transport from shelf to the deep basin include: (i) seabed morphology, (ii) climate, (iii) sea level changes, (iv) slope stability, (v) oceanographic regime, and (vi) sediment sources. In order to understand the recent sedimentary processes along the western margin of the South Korea Plateau in the East Sea, we collected multiple geophysical datasets including the subbottom profiler and multibeam echosounder as well as geological sampling. Twelve echo types have been defined and interpreted as deposits formed by shallow marine, hemipelagic sedimentation, bottom currents, combined- (mass-movement/hemipelagic and hemipelagic/turbidites) and mass-movement-processes. Hemipelagic sedimentation, which is reflected as undisturbed layered sediments, appears to have been the primary sedimentary process throughout the study area. Two major slope-parallel channels appear to have acted as major conduits for turbidity currents from shallower shelf into the deep basins. Bottom current deposits, which is expressed as undulating seafloor morphology, are prevalent in the southern mid-slope at water depths between 250 to 450 m. Mass-transport deposits, consisting of chaotic seismic facies, occur in the upper and lower parts of the continental slope. Piston cores confirm the presence of MTDs that are characterized by mud clasts of variable size and shape. Multibeam bathymetry data show that these MTDs chiefly initiate on lower-slopes (400-600 m) where the gradient is up to 3°. In addition, subbottom profiles suggest the presence of numerous faults in close vicinity of headwall scarps; some are extending to the seafloor suggesting their recent activity. Earthquakes associated with tectonic activity are considered as the main triggering mechanism for these MTDs. Overall, the acoustic facies

Spatio-temporal evolution of the 2011 Prague, Oklahoma aftershock sequence revealed using subspace detection and relocation

Science.gov (United States)

McMahon, Nicole D; Aster, Richard C.; Yeck, William; McNamara, Daniel E.; Benz, Harley M.

2017-01-01

The 6 November 2011 Mw 5.7 earthquake near Prague, Oklahoma is the second largest earthquake ever recorded in the state. A Mw 4.8 foreshock and the Mw 5.7 mainshock triggered a prolific aftershock sequence. Utilizing a subspace detection method, we increase by fivefold the number of precisely located events between 4 November and 5 December 2011. We find that while most aftershock energy is released in the crystalline basement, a significant number of the events occur in the overlying Arbuckle Group, indicating that active Meeker-Prague faulting extends into the sedimentary zone of wastewater disposal. Although the number of aftershocks in the Arbuckle Group is large, comprising ~40% of the aftershock catalog, the moment contribution of Arbuckle Group earthquakes is much less than 1% of the total aftershock moment budget. Aftershock locations are sparse in patches that experienced large slip during the mainshock.

THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).

Science.gov (United States)

Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene

2011-12-01

Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] macrophyte, nutrient-limited lakes (BiomEpiV macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance. © 2011 Phycological Society of America.

Distribution and relative quantification of key genes involved in fixed nitrogen loss from the Arabian Sea oxygen minimum zone

Digital Repository Service at National Institute of Oceanography (India)

Jayakumar, A.; Naqvi, S.W.A.; Ward, B.B.

diversity than the very high diversities reported from estuarine and sedimentary environments. 16S rRNA partial gene sequences revealed very limited diversity among anammox sequences. All the anammox sequences were greater than or equal to 98% identical...

Geological factors of the isotopic distribution of carbon of organic matter in sedimentary rocks

International Nuclear Information System (INIS)

Maass, J.

1981-01-01

The isotope ratio of carbon of fossile organic matter can be regarded as a definite criterion of its genetic origin. As the biofacial character of organic matter, especially the chemical composition (H/C-ratio), decisively influences the mode and quantity of the potential hydrocarbon production, isotopic analysis is an essential method for the prognostic evaluation of sedimentary basins with regard to their oil and gas perspectives. The genetic relations to the parent substance continue in the bituminization and coalification products and make it possible to apply the isotopic analysis of carbon to prospection work for hydrocarbons. (author)

An examination of recharge mound decay and fossil gradients in arid regional sedimentary basins

International Nuclear Information System (INIS)

Lloyd, J.W.

1980-01-01

In many of the vast arid sedimentary basins of the world, groundwater gradients exist that appear to be anomalous in the context of the probable modern recharge potential. The possibility that such gradients are in fact remnant fossil conditions representing the decay of ancient recharge mounds is examined. An example of decay condition is represented using a resistor-network analogue model in which the time control is based on 14 C ages. The decay hypothesis is found to be plausible with realistic aquifer characteristics but a non-homogeneous flow is indicated from the 14 C data. (author)

Investigating Coccolithophorid Biology in the Sedimentary Laboratory

Science.gov (United States)

McClelland, H. L. O.; Barbarin, N.; Beaufort, L.; Hermoso, M.; Rickaby, R. E. M.

2014-12-01

Coccolithophores are the ocean's dominant calcifying phytoplankton; they play an important, but poorly understood, role in long-term biogeochemical climatic feedbacks. Calcite producing marine organisms are likely to calcify less in a future world where higher carbon dioxide concentrations will lead to ocean acidification (OA), but coccolithophores may be the exception. In coccolithophores calcification occurs in an intracellular vesicle, where the site of calcite precipitation is buffered from the external environment and is subject to a uniquely high degree of biological control. Culture manipulation experiments mimicking the effects of OA in the laboratory have yielded empirical evidence for phenotypic plasticity, competition and evolutionary adaptation in asexual populations. However, the extent to which these results are representative of natural populations, and of the response over timescales of greater than a few hundred generations, is unclear. Here we describe a new sediment-based proxy for the PIC:POC (particulate inorganic to particulate organic carbon ratio) of coccolithophore biomass, which is equivalent to the fractional energy contribution to calcification at constant pH, and a biologically meaningful measure of the organism's tendency to calcify. Employing the geological record as a laboratory, we apply this proxy to sedimentary material from the southern Pacific Ocean to investigate the integrated response of real ancient coccolithophore populations to environmental change over many thousands of years. Our results provide a new perspective on phenotypic change in real populations of coccolithophorid algae over long timescales.

Holocene depocenter migration and sediment accumulation in Delaware Bay: A submerging marginal marine sedimentary basin

Science.gov (United States)

Fletcher, C. H.; Knebel, H.J.; Kraft, J.C.

1992-01-01

The Holocene transgression of the Delaware Bay estuary and adjacent Atlantic coast results from the combined effect of regional crustal subsidence and eustasy. Together, the estuary and ocean coast constitute a small sedimentary basin whose principal depocenter has migrated with the transgression. A millenial time series of isopach and paleogeographic reconstructions for the migrating depocenter outlines the basin-wide pattern of sediment distribution and accumulation. Upland sediments entering the basin through the estuarine turbidity maximum accumulate in tidal wetland or open water sedimentary environments. Wind-wave activity at the edge of the tidal wetlands erodes the aggraded Holocene section and builds migrating washover barriers. Along the Atlantic and estuary coasts of Delaware, the area of the upland environment decreases from 2.0 billion m2 to 730 million m2 during the transgression. The area of the tidal wetland environment increases from 140 million to 270 million m2, and due to the widening of the estuary the area of open water increases from 190 million to 1.21 billion m2. Gross uncorrected rates of sediment accumulation for the tidal wetlands decrease from 0.64 mm/yr at 6 ka to 0.48 mm/yr at 1 ka. In the open water environments uncorrected rates decrease from 0.50 mm/yr to 0.04 mm/yr over the same period. We also present data on total sediment volumes within the tidal wetland and open water environments at specific intervals during the Holocene. 

Architecture of Maastrichtian carbonate deposits of the United Arab Emirates and Oman Sultanate border region; Architecture des corps carbonates du Maastrichtien de la zone frontaliere Emirats Arabes Unis - Sultanat d'Oman

Energy Technology Data Exchange (ETDEWEB)

Vennin, E. [Museum National d' Histoire Naturelle, 75 - Paris (France); Barrier, P. [Institut Geologique Alber-de-Lapparent (France); Soudet, H.J. [Societe ELF, 75 - Paris (France); Bideau, T.; Proudhon, B. [Elf Exploration Production, 64 - Pau (France); Cogema, 78 - Velizy-Villacoublay (France)

1999-09-01

This paper discusses the sedimentary model, sequence framework and geometry quantification of sedimentary bodies in an Upper Cretaceous carbonate platform, abounding in oil reservoirs. The outcrops are located along the western margin of the northern Oman Mountains in the border region of the United Arab Emirates and the Sultanate of Oman. The Maastrichtian Simsima Formation outcrops on several N-S-trending jebels, situated between the localities of Al Dhaid and Al Ain. Jebel Rawdah was studied in detail, whereas Jebel Faiyah is documented as another reference section for correlation purposes. A sedimentary reconstruction of the latest Campanian - Late Maastrichtian interval displays a gradual change from tidal flat and fore-shore to outer platform settings. This evolution shows the flooding of the study area after Late Campanian times. Two third-order sequences were identified on the Maastrichtian intra-platform ramps. Both of them can be subdivided into a complex arrangement of 4. and 5. order sequences. Third-order sequences exhibit composite features and contain aggradational/retro-gradational and pro-gradational trends. A direct relationship was identified between the sequence framework and the palaeo-ecological distribution of reef builder and free organisms. The former developed essentially in retro-gradational trends whereas the benthic foraminifera Loftusia commonly appears in platform flooding intervals, and orbitoids mainly occur within pro-gradational trends. Widespread sedimentary tectonic activity is documented in the palaeo-geographic reconstruction of the Simsima Formation. Several palaeo-highs and grabens, related to the general foreland basin context of the UAE platform, are recognised in the Jebel Rawdah. Finally, the sequence framework of the Simsima Formation in the Jebel Falyah is similar to that of the Jebel Rawdah and makes it possible to propose an accurate sequence framework correlation. (authors)

Uranium favorability of tertiary sedimentary rocks of the western Okanogan highlands and of the upper Columbia River valley, Washington

International Nuclear Information System (INIS)

Marjaniemi, D.K.; Robins, J.W.

1975-08-01

Tertiary sedimentary rocks in the northern portions of the western Okanogan highlands and in the upper Columbia River valley were investigated during a regional study to determine the favorability for potential uranium resources of the Tertiary sedimentary rocks of northeastern Washington. This project involved measurement and sampling of surface sections, collection of samples from isolated outcrops, and chemical and mineralogical analyses of samples. No portion of the project area of this report is rated of high or of medium favorability for potential uranium resources. Low favorability ratings are given to Oroville, Tonasket, and Pine Creek areas of the Okanogan River valley; to the Republic graben; and to the William Lakes, Colville, and Sheep Creek areas of the upper Columbia River valley. All these areas contain some fluvial, poorly sorted feldspathic or arkosic sandstones and conglomerates. These rocks are characterized by very low permeability and a consistently high siliceous matrix suggesting very low initial permeability. There are no known uranium deposits in any of these areas, and low level uranium anomalies are rare

In-situ monitoring of deformation of clayey and volcanic sequences in the lacustrine plain of Iztapalapa, Mexico City

Science.gov (United States)

Carreon-Freyre, D.; Cerca, M.; Barrientos, B.; Gutierrez, R.; Blancas, D.

2012-12-01

Major cities of Central Mexico with lowering of land elevation problems are located in inter-volcanic and fault bounded basins within the central Trans-Mexican Volcanic Belt (TMVB). The most representative and studied case of ground deformation is Mexico City, where the Iztapalapa Municipality presents the highest population density. This area is located over the geological contact between the "Sierra de Santa Catarina" volcanic range and a lacustrine plain. Filling of lacustrine basins includes silty and clayey sediments as well as pyroclastic deposits (coarse and fine grained) and volcanic rocks layers. We used Ground Penetrating Radar (GPR) and MASW prospection to evaluate contrasts in the physical properties of fine grained soils and identify geometry of the deformational features and implemented a mechanical system for in situ monitoring in fractured sites. Deformational features in this basin reflect an interplay between the geological history (depositional conditions), load history, seismic activity, and faulting. Plastic mechanical behaviour predominates in these clayey sediments and differential deformation locally triggers brittle fracturing and/or subsidence of the surface. In this work we present the results of monitoring and characterization of ground deformation and fracturing in different sequences, our results show a dynamic interplay between the mechanisms of ground fracturing and the stress history of sedimentary sequences. Relating the mechanical behaviour of the studied sequences with variations of physical and geological properties should be taken into account to estimate land level lowering and risk of fracturing for urban development planning.

210Pb dating of sediments from the central and the northern Adriatic Sea: The deposition and preservation of sedimentary organic carbon

International Nuclear Information System (INIS)

Hamilton, T.; Fowler, S.; Miquel, J.C.; La Rosa, J.

1996-04-01

A central goal of the ELNA project is to assess the carbon assimilation capacity of the Northern Adriatic Sea. This requires fundamental quantitative information on budgets and sinks of organic carbon. Any change in carbon production in the water column should be reflected in the underlying sediments. Moreover, the fraction of particulate organic carbon reaching the sea floor which is subsequently preserved in the sediment will be strongly coupled to sediment accumulation and mixing. In this study a series of box cores were collected in order to characterize a hypothetical eutrophication gradient extending from the Po River outflow region in the north down to the shallow meso-Adriatic depression (Jabuka Pit). The main tasks assigned to IAEA-MEL were to provide 210 Pb derived sedimentation and dry-mass accumulation rates and to examine the possible correlations between sedimentary processes, the deposition and preservation of sedimentary organic carbon and pelagic primary productivity

Late Paleozoic paleofjord in the southernmost Parana Basin (Brazil): Geomorphology and sedimentary fill

Science.gov (United States)

Tedesco, Julia; Cagliari, Joice; Coitinho, Julia dos Reis; da Cunha Lopes, Ricardo; Lavina, Ernesto Luiz Correa

2016-09-01

In the southernmost part of the Parana Basin, records of the late Paleozoic glaciation occur in a discontinuous form preserved in paleovalley systems excavated in the crystalline basement. This paper addresses one of these paleovalleys, the Mariana Pimentel, which extends over 60 km with NW-SE valley direction and a constant width of 2.5 km. With the objective of demonstrating that the paleovalley worked as a fjord during the glaciation period, its origin as well as sedimentary fill and morphology were analyzed. The paleovalley morphology was obtained through electrical resistivity (electrical sounding and lateral mapping) and mathematical modeling in four transverse sections. The morphology of the paleovalley documented by the U-shape, steady width, and high depth reaching up to 400 m are typical features of modern glacial valleys. The sedimentary facies that fill the base of the paleovalley, such as rhythmites and dropstones with thickness up to 70 m and diamictites with faceted pebbles (up to 5 m thick) are signs of its glacial origin. During the glaciation period, the paleovalley had a connection to the epicontinental sea located to the northwest, extended toward Namibia, and was excavated by glaciers from the highlands of this region. Thus, the evidence attests that the Mariana Pimentel paleovalley was a fjord during the late Paleozoic glaciation. The duration of the late Paleozoic glaciation (which is longer than the Quaternary glaciation), the apatite fission track that suggests erosion up to 4 km thick in the study area, and the lack of preserved hanging valleys in the Mariana Pimentel indicate that the paleovalley once featured a higher dimension. Furthermore, the existence of paleofjords excavated in the border of the basement corroborates the idea of small ice centers controlled by topography during the late Paleozoic glaciation.

Late to middle Pleistocene Arctic glacial history implied from a sedimentary record from the Northwind Ridge

Science.gov (United States)

Liu, Y.; Dong, L.; Shi, X.; Zhu, A.

2017-12-01

Abstract: Sediment core ARC6-C21 collected from the Northwind Ridge, western Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stages (MIS) 1-11), as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of the elemental composition of sediment along with grain size in core ARC6-C21 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from geochemical composition. Notably, peaks of MgO and CaO, including large dropstones, presumably track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) and/or Eurasia Ice Sheet (EIS)are inferred from peaks of SiO2, K2O and Na2O associated with coarse sediment. Major ESIS and/or EIS sedimentary events occurred in the intervals estimated as MIS 2, MIS 4, MIS 6, MIS 8 and MIS 10. Keywords: Sediment core, Pleistocene, western Arctic Ocean, geochemistry, grain size, sediment provenance, glaciations

Different controls on sedimentary organic carbon in the Bohai Sea: River mouth relocation, turbidity and eutrophication

Science.gov (United States)

Xu, Yunping; Zhou, Shangzhe; Hu, Limin; Wang, Yinghui; Xiao, Wenjie

2018-04-01

The extractable lipids and bulk organic geochemical parameters in three sediment cores (M-1, M-3 and M-7) from southern, central and northern Bohai Sea were analyzed in order to reconstruct environmental changes since 1900. The C/N ratio and multiple biomarkers (e.g., C27 + C29 + C31n-alkanes, C24 + C26 + C28n-alkanols, branched versus isoprenoid tetraether index) suggest more terrigenous organic carbon (OC) inputs in southern Bohai Sea. The abrupt changes of biomarker indicators in core M-1 are generally synchronous with the Yellow River mouth relocation events (e.g., 1964, 1976 and 1996), suggesting the distance to the river mouth being an important factor for sedimentary OC dispersal in the southern Bohai Sea. However, in cores M-3 and M-7, terrigenous biomarkers (i.e., BIT) show a long-term declining trend, consistent with a continuous reduction of the Yellow River sediment load, whereas marine biomarkers such as cholesterol, brassicasterol and dinosterol dramatically increased post-1980, apparently related to human-induced eutrophication in the Bohai Sea. Our study suggests different controlling factors on sedimentary OC distribution in the southern (high turbidity) and other parts (less turbidity) of the Bohai Sea, which should be considered for interpretation of paleoenvironments and biogeochemical processes in the river dominated margins that are hotspots of the global carbon cycling.

Inverse modeling of geochemical and mechanical compaction in sedimentary basins

Science.gov (United States)

Colombo, Ivo; Porta, Giovanni Michele; Guadagnini, Alberto

2015-04-01

We study key phenomena driving the feedback between sediment compaction processes and fluid flow in stratified sedimentary basins formed through lithification of sand and clay sediments after deposition. Processes we consider are mechanic compaction of the host rock and the geochemical compaction due to quartz cementation in sandstones. Key objectives of our study include (i) the quantification of the influence of the uncertainty of the model input parameters on the model output and (ii) the application of an inverse modeling technique to field scale data. Proper accounting of the feedback between sediment compaction processes and fluid flow in the subsurface is key to quantify a wide set of environmentally and industrially relevant phenomena. These include, e.g., compaction-driven brine and/or saltwater flow at deep locations and its influence on (a) tracer concentrations observed in shallow sediments, (b) build up of fluid overpressure, (c) hydrocarbon generation and migration, (d) subsidence due to groundwater and/or hydrocarbons withdrawal, and (e) formation of ore deposits. Main processes driving the diagenesis of sediments after deposition are mechanical compaction due to overburden and precipitation/dissolution associated with reactive transport. The natural evolution of sedimentary basins is characterized by geological time scales, thus preventing direct and exhaustive measurement of the system dynamical changes. The outputs of compaction models are plagued by uncertainty because of the incomplete knowledge of the models and parameters governing diagenesis. Development of robust methodologies for inverse modeling and parameter estimation under uncertainty is therefore crucial to the quantification of natural compaction phenomena. We employ a numerical methodology based on three building blocks: (i) space-time discretization of the compaction process; (ii) representation of target output variables through a Polynomial Chaos Expansion (PCE); and (iii) model

The sedimentary record and petrophysical logs from the Spanish Central Pyrenees: Implications for paleoclimate change in the Early Devonian

Czech Academy of Sciences Publication Activity Database

Slavík, Ladislav; Valenzuela-Ríos, J. I.; Hladil, Jindřich; Chadimová, Leona; Liao, J-Ch.; Hušková, Aneta; Calvo, H.; Hrstka, Tomáš

2015-01-01

Roč. 21, - (2015), s. 350-350 ISSN 1608-8166. [International Congress on Stratigraphy /2./. STRATI 2015. 19.07.2015-23.07.2015, Graz] Institutional support: RVO:67985831 Keywords : stratigraphy * Early Devonian * sedimentary record * paleoclimate change * Spanish Central Pyrenees Subject RIV: DB - Geology ; Mineralogy http://www.zobodat.at/pdf/Ber-Inst-Erdwiss-Univ-Graz_21_0001-0437.pdf

A MATLAB®-based program for 3D visualization of stratigraphic setting and subsidence evolution of sedimentary basins: example application to the Vienna Basin

Science.gov (United States)

Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

2015-04-01

In recent years, 3D visualization of sedimentary basins has become increasingly popular. Stratigraphic and structural mapping is highly important to understand the internal setting of sedimentary basins. And subsequent subsidence analysis provides significant insights for basin evolution. This study focused on developing a simple and user-friendly program which allows geologists to analyze and model sedimentary basin data. The developed program is aimed at stratigraphic and subsidence modelling of sedimentary basins from wells or stratigraphic profile data. This program is mainly based on two numerical methods; surface interpolation and subsidence analysis. For surface visualization four different interpolation techniques (Linear, Natural, Cubic Spline, and Thin-Plate Spline) are provided in this program. The subsidence analysis consists of decompaction and backstripping techniques. The numerical methods are computed in MATLAB® which is a multi-paradigm numerical computing environment used extensively in academic, research, and industrial fields. This program consists of five main processing steps; 1) setup (study area and stratigraphic units), 2) loading of well data, 3) stratigraphic modelling (depth distribution and isopach plots), 4) subsidence parameter input, and 5) subsidence modelling (subsided depth and subsidence rate plots). The graphical user interface intuitively guides users through all process stages and provides tools to analyse and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the visualization results using the full range of available plot options in MATLAB. All functions of this program are illustrated with a case study of Miocene sediments in the Vienna Basin. The basin is an ideal place to test this program, because sufficient data is

Effect of hydro mechanical coupling on natural fracture network formation in sedimentary basins

Science.gov (United States)

Ouraga, Zady; Guy, Nicolas; Pouya, Amade

2018-05-01

In sedimentary basin context, numerous phenomena, depending on the geological time span, can result in natural fracture network formation. In this paper, fracture network and dynamic fracture spacing triggered by significant sedimentation rate are studied considering mode I fracture propagation using a coupled hydro-mechanical numerical methods. The focus is put on synthetic geological structure under a constant sedimentation rate on its top. This model contains vertical fracture network initially closed and homogeneously distributed. The fractures are modelled with cohesive zone model undergoing damage and the flow is described by Poiseuille's law. The effect of the behaviour of the rock is studied and the analysis leads to a pattern of fracture network and fracture spacing in the geological layer.

Universal sequence map (USM of arbitrary discrete sequences

Directory of Open Access Journals (Sweden)

Almeida Jonas S

2002-02-01

Full Text Available Abstract Background For over a decade the idea of representing biological sequences in a continuous coordinate space has maintained its appeal but not been fully realized. The basic idea is that any sequence of symbols may define trajectories in the continuous space conserving all its statistical properties. Ideally, such a representation would allow scale independent sequence analysis – without the context of fixed memory length. A simple example would consist on being able to infer the homology between two sequences solely by comparing the coordinates of any two homologous units. Results We have successfully identified such an iterative function for bijective mappingψ of discrete sequences into objects of continuous state space that enable scale-independent sequence analysis. The technique, named Universal Sequence Mapping (USM, is applicable to sequences with an arbitrary length and arbitrary number of unique units and generates a representation where map distance estimates sequence similarity. The novel USM procedure is based on earlier work by these and other authors on the properties of Chaos Game Representation (CGR. The latter enables the representation of 4 unit type sequences (like DNA as an order free Markov Chain transition table. The properties of USM are illustrated with test data and can be verified for other data by using the accompanying web-based tool:http://bioinformatics.musc.edu/~jonas/usm/. Conclusions USM is shown to enable a statistical mechanics approach to sequence analysis. The scale independent representation frees sequence analysis from the need to assume a memory length in the investigation of syntactic rules.

Sedimentary Evolution of Marginal Ganga Foreland Basin during the Late Pleistocene

Science.gov (United States)

Ghosh, R.; Srivastava, P.; Shukla, U. K.

2017-12-01

Ganga foreland basin, an asymmetrical basin, was formed as result of plate-plate collision during middle Miocene. A major thrust event occurred during 500 ka when upper Siwalik sediments were uplifted and the modern Ganga foreland basin shifted towards craton, making a more wide and deep basin. The more distal part of this basin, south of axial river Yamuna, records fluvial sedimentary packages that helps to understand dynamics of peripheral bulge during the late Quaternary. Sedimentary architecture in conjunction with chemical index of alteration (CIA), paleocurrent direction and optically stimulated dating (OSL) from 19 stratigraphic sections helped reconstructing the variations in depositional environments vis-à-vis climate change and peripheral bulge tectonics. Three major units (i) paleosol; (ii) cratonic gravel; (iii) interfluve succession were identified. The lower unit-I showing CIA values close to 70-80 and micro-morphological features of moderately well-developed pedogenic unit that shows development of calcrete, rhizoliths, and mineralized organic matter in abundance. This is a regional paleosols unit and OSL age bracketed 200 ka. This is unconformably overlain by unit-II, a channelized gravel composed of sub-angular to sub-rounded clasts of granite, quartz, quartzite, limestone and calcrete. The gravel have low CIA value up to 55, rich in vertebrate fossil assemblages and mean paleocurrent vector direction is NE, which suggesting deposition by a fan of a river draining craton into foreland. This unit is dated between 100 ka and 54 ka. The top unit-III, interfluve succession of 10-15 m thick is composed of dark and light bands of sheet like deposit of silty clay to clayey silt comprises sand lenses of red to grey color and displaying top most OSL age is 12 ka. The basal mature paleosol signifies a humid climate developed under low subsidence rate at >100 ka. After a hiatus represented by pedogenic surface deposition of unit-II (gravel) suggests uplift

Geochemistry of Precambrian sedimentary rocks used to solve stratigraphical problems: An example from the Neoproterozoic Volta basin, Ghana

DEFF Research Database (Denmark)

Kalsbeek, F.; Frei, Robert

2010-01-01

The Neoproterozoic Volta basin of Ghana (not, vert, similar115,000 km2; depth up to 5–7 km) consists of flat-lying sedimentary rocks, mainly sandstones that unconformably overlie the crystalline basement of the West-African craton. The stratigraphical column has been subdivided into three main...... and Obosum Groups is used to solve one of the outstanding controversies regarding the stratigraphy of the Volta basin....

Is sequence awareness mandatory for perceptual sequence learning: An assessment using a pure perceptual sequence learning design.

Science.gov (United States)

Deroost, Natacha; Coomans, Daphné

2018-02-01

We examined the role of sequence awareness in a pure perceptual sequence learning design. Participants had to react to the target's colour that changed according to a perceptual sequence. By varying the mapping of the target's colour onto the response keys, motor responses changed randomly. The effect of sequence awareness on perceptual sequence learning was determined by manipulating the learning instructions (explicit versus implicit) and assessing the amount of sequence awareness after the experiment. In the explicit instruction condition (n = 15), participants were instructed to intentionally search for the colour sequence, whereas in the implicit instruction condition (n = 15), they were left uninformed about the sequenced nature of the task. Sequence awareness after the sequence learning task was tested by means of a questionnaire and the process-dissociation-procedure. The results showed that the instruction manipulation had no effect on the amount of perceptual sequence learning. Based on their report to have actively applied their sequence knowledge during the experiment, participants were subsequently regrouped in a sequence strategy group (n = 14, of which 4 participants from the implicit instruction condition and 10 participants from the explicit instruction condition) and a no-sequence strategy group (n = 16, of which 11 participants from the implicit instruction condition and 5 participants from the explicit instruction condition). Only participants of the sequence strategy group showed reliable perceptual sequence learning and sequence awareness. These results indicate that perceptual sequence learning depends upon the continuous employment of strategic cognitive control processes on sequence knowledge. Sequence awareness is suggested to be a necessary but not sufficient condition for perceptual learning to take place. Copyright © 2018 Elsevier B.V. All rights reserved.

Mapping Neogene and Quaternary sedimentary deposits in northeastern Brazil by integrating geophysics, remote sensing and geological field data

Science.gov (United States)

Andrades-Filho, Clódis de Oliveira; Rossetti, Dilce de Fátima; Bezerra, Francisco Hilario Rego; Medeiros, Walter Eugênio; Valeriano, Márcio de Morisson; Cremon, Édipo Henrique; Oliveira, Roberto Gusmão de

2014-12-01

Neogene and late Quaternary sedimentary deposits corresponding respectively to the Barreiras Formation and Post-Barreiras Sediments are abundant along the Brazilian coast. Such deposits are valuable for reconstructing sea level fluctuations and recording tectonic reactivation along the passive margin of South America. Despite this relevance, much effort remains to be invested in discriminating these units in their various areas of occurrence. The main objective of this work is to develop and test a new methodology for semi-automated mapping of Neogene and late Quaternary sedimentary deposits in northeastern Brazil integrating geophysical and remote sensing data. The central onshore Paraíba Basin was selected due to the recent availability of a detailed map based on the integration of surface and subsurface geological data. We used airborne gamma-ray spectrometry (i.e., potassium-K and thorium-Th concentration) and morphometric data (i.e., relief-dissection, slope and elevation) extracted from the digital elevation model (DEM) generated by the Shuttle Radar Topography Mission (SRTM). The procedures included: (a) data integration using geographic information systems (GIS); (b) exploratory statistical analyses, including the definition of parameters and thresholds for class discrimination for a set of sample plots; and (c) development and application of a decision-tree classification. Data validation was based on: (i) statistical analysis of geochemical and airborne gamma-ray spectrometry data consisting of K and Th concentrations; and (ii) map validation with the support of a confusion matrix, overall accuracy, as well as quantity disagreement and allocation disagreement for accuracy assessment based on field points. The concentration of K successfully separated the sedimentary units of the basin from Precambrian basement rocks. The relief-dissection morphometric variable allowed the discrimination between the Barreiras Formation and the Post-Barreiras Sediments. In

Geochemical element mobility during the history of a Paleo-proterozoic clastic sedimentary basin, the Athabasca Basin (Saskatchewan, Canada)

International Nuclear Information System (INIS)

Kister, Philippe

2003-01-01

In order to understand the mechanisms of migration and deposition of ore elements, it is essential to determine the timing, source, and destination of the geochemical element mass transfers and/or transportation on a scale encompassing the great sedimentary basins. The purpose of this study is to trace and to date the element migrations that occurred during the history of a Paleo-proterozoic clastic sedimentary basin, the Athabasca Basin, which hosts the world's largest and richest uranium deposits. As this geological environment was proved to be efficient to preserve high grade ore deposits for over more than one billion years, it provides an opportunity to study some natural analogues of deep geological nuclear waste storage. Five research topics were studied: 3D modelling of the distribution of normative minerals and trace elements on a basin-wide scale; U-Pb and Rb-Sr systematics; average chemical age estimation; thermodynamic modelling of the major mineralogical assemblages; U-Pb geochronology of uranium oxides. Some elements have remained immobile (Zr) since their initial sedimentary deposition, or were transferred from one phase to another (Al, Th). Other elements have been transported during fluid flow events that occurred: (1) on a basin wide scale during diagenesis (REE, Y, Sr, Fe), (2) at the unconformity and in the vicinity of the fault zones that represent preferential fluid flow pathways between the basement and the sandstone cover (U, Ni, As, B, Mg, K, Fe, Sr, REE), (3) during the late fault reactivation events associated with the basin uplift (U, Pb, Ni, S, Sr, REE). The successive tectonic events related to the geodynamical context that lead to the formation of these high-grade U concentrations (1460 Ma, 1335 Ma and 1275 Ma in the McArthur River deposit), did not however systematically occur in the whole basin (1275 Ma only at Shea Creek). The exceptionally high grade and tonnages of some deposits seem to be related to a larger number of U

Sedimentary Records of Hyperpycnal Flows and the Influence of River Damming on Sediment Dynamics of Estuaries: Examples from the Nelson, Churchill, Moisie and Sainte-Marguerite Rivers (Canada)

Science.gov (United States)

St-Onge, G.; Duboc, Q.; Boyer-Villemaire, U.; Lajeunesse, P.; Bernatchez, P.

2015-12-01

Sediment cores were sampled in the estuary of the Nelson and Churchill Rivers in western Hudson Bay, as well as in the estuary of the Moisie and Sainte-Marguerite Rivers in Gulf of St. Lawrence in order to evaluate the impact of hydroelectric dams on the sedimentary regime of these estuaries. The gravity cores at the mouth of the Nelson River recorded several cm-thick rapidly deposited layers with a reverse to normal grading sequence, indicating the occurrence of hyperpycnal flows generated by major floods during the last few centuries. These hyperpycnal flows were probably caused by ice-jam formation, which can increase both the flow and the sediment concentration following the breaching of such natural dams. Following the construction of hydroelectric dams since the 1960s, the regulation of river discharge prevented the formation of hyperpycnal flows, and hence the deposition of hyperpycnites in the upper part of the cores. In the core sampled in the estuary of the Churchill River, only one hyperpycnite was recorded. This lower frequency may be due to the enclosed estuary of the Churchill River, its weaker discharge and the more distal location of the coring site.In the Gulf of St. Lawrence, grain size measurements allowed the identification of a major flood around AD 1844±4 years in box cores from both the Sainte-Marguerite and Moisie Rivers, whereas a drastic decrease in variations in the median grain size occurred around AD ~1900 in the estuary of the Sainte-Marguerite River, highlighting the offshore impact of the SM1 dam construction in the early 1900s. Furthermore, sedimentological variations in the box cores from both estuaries have been investigated by wavelet analysis and the sharp disappearance of high frequencies around AD 1900 in the estuary of the dammed river (Sainte-Marguerite River), but not in the estuary of the natural river (Moisie River), also provides evidence of the influence of dams on the sedimentary regime of estuaries.

Ore reserve calculations of a sedimentary uranium deposit in Figueira, PR-Brazil

International Nuclear Information System (INIS)

Guerra, P.A.G.; Censi, A.C.; Marques, J.P.M.; Huijbregts, Ch.

1978-01-01

The are reserve calculations of a sedimentary uranium deposit in Figueira-PR-Brazil are presented. The evalution of reserves was based on chemical and/or radiometric analisys from boreholes. Geoestatistical methods were used to study the spacial correlation between radiometric and'in situ' uranium content and to calculate the equivalent uranium content without the need for chemical analysis. To this end, a new method was developed based on the regression between accumulated chemical and radiometric grades as determined by increasing thicknesses defined from the maximum peak of the γ-ray logs. Thus, the effect of non-focalization of the probe and of the continuous logging was eliminated. The system of evalution used was two-dimensional using classical Kriging to calculate thicknesses and accumulations determined using distinct cut-off grades. (Author) [pt

A study of radionuclide transfer between invertebrates and their marine sedimentary environment

International Nuclear Information System (INIS)

Amiard-Triquet, Claude.

1975-11-01

Exchanges between sediment and marine organisms were studied in some benthic marine invertebrates, especially Arenicola marina L. (an Annelid). Experiments were carried out on the transfer of 60 Co, 137 Cs and accessorily 59 Fe and 144 Ce. Water was the chief vector for benthic marine invertebrates. These invertebrates seemed to act mainly in sedimentary areas on the redistribution of adsorbed radionuclides within the sediment. Radioactive contamination of the invertebrates was affected by various physiological or ecological factors. Benthic marine invertebrates were then studied as links in food chains. The transfer of 60 Co was studied in three food chains or fractions of food chains. The procedure allowed interesting observations from the health protection point of view and more fundamental investigations on cobalt metabolism (regulation, excretion) in a mollusc, a crustacea and a teleost [fr

The role microbial sulfate reduction in the direct mediation of sedimentary authigenic carbonate precipitation

Science.gov (United States)

Turchyn, A. V.; Walker, K.; Sun, X.

2016-12-01

The majority of modern deep marine sediments are bathed in water that is undersaturated with respect to calcium carbonate. However, within marine sediments changing chemical conditions, driven largely by the microbial oxidation of organic carbon in the absence of oxygen, lead to supersaturated conditions and drive calcium carbonate precipitation. This sedimentary calcium carbonate is often called `authigenic carbonate', and is found in the form of cements and disseminated crystals within the marine sedimentary pile. As this precipitation of this calcium carbonate is microbially mediated, identifying authigenic carbonate within the geological record and understanding what information its geochemical and/or isotopic signature may hold is key for understanding its importance and what information it may contain past life. However, the modern controls on authigenic carbonate precipitation remain enigmatic because the myriad of microbially mediated reactions occurring within sediments both directly and indirectly impact the proton balance. In this submission we present data from 25 ocean sediment cores spanning the globe where we explore the deviation from the stoichiometrically predicted relationships among alkalinity, calcium and sulfate concentrations. In theory for every mol of organic carbon reduced by sulfate, two mol of alkalinity is produced, and to precipitate subsurface calcium carbonate one mol of calcium is used to consume two mol of alkalinity. We use this data with a model to explore changes in carbonate saturation state with depth below the seafloor. Alkalinity changes in the subsurface are poorly correlated with changes in calcium concentrations, however calcium concentrations are directly and tightly coupled to changes in sulfate concentrations in all studied sites. This suggests a direct role for sulfate reducing bacteria in the precipitation of subsurface carbonate cements.

Provenance of Neoproterozoic to upper Cretaceous sedimentary rocks, eastern Greenland: Implications for recognizing the sources of sediments in the Norwegian Sea

Czech Academy of Sciences Publication Activity Database

Sláma, Jiří; Walderhaug, O.; Fonneland, H.; Kosler, J.; Pederson, R. B.

2011-01-01

Roč. 238, 3/4 (2011), s. 254-267 ISSN 0037-0738 Institutional research plan: CEZ:AV0Z30130516 Keywords : sedimentary * Eastern Greenland * provenance * U-Pb and Lu-Hf * zircon * Jan Mayen Island * North Atlantic Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.537, year: 2011

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Science.gov (United States)

Shimeld, John; Li, Qingmou; Chian, Deping; Lebedeva-Ivanova, Nina; Jackson, Ruth; Mosher, David; Hutchinson, Deborah R.

2016-01-01

The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity–depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km2. The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity–depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity–depth profiles for each seismic trace. A thickness of 12–13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity–depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares

The Punta del Este terrain and its volcano sedimentary cover, metamorphic and sedimentary: geology, geochemistry and geochronology

International Nuclear Information System (INIS)

Preciozzi, F.

2015-01-01

Gariep belt it develops over the West Africa coastal region of Namibia underlying on Namaqua metamorphic complex.It characterized by supra crustal rocks affected for a very low to low metamorphism and in two tecto no-stratigraphic units identified by Base i et al 2005 showing that sediments of Formation Rocha in Uruguay and the Group Oranjemund Gariep in S E Africa have similar ages in the provenance of the zircons, suggesting that they were probably deposited in the same basin. This unit exhibits detrital zircons around 600my, sedimentation and metamorphism and deformación occur in a narrow time interval from 600-610 to 574 m (Granite de Castillo intrusion) .Cam pal et al, 2005 proposed to the Cerros Aguirre Formation similar in a range of age of different events. To the east separated from the Punta del Este Terrane –Pelotas. Aigua .Florianopolis batholith s by the shear zone Alferez Cordillera (Preciozzi et al. 1999, Basei et al. 2000) Another option develops this granitic belt is an integral part of Land Punta del Este Terrane(Preciozzi in this work), being deployed on a thin cratonic granite edge. The climax of the post-brasilian magmatism is 580my, strongly related to trans current movements (eg shear zones Major Gercino-Alferez- Cordillera and Sierra Ballena.In South America an old west domain is formed by the Piedra Alta Terrane which integrate the Río de la Pl ata Craton, a central domain intensely reworked by Neoproterozoic events known so far as Nico Perez . The primary coverage is integrated by two volcano-sedimentary basins (San Carlos Formation and Cerros de Aguirre Formation)In this study are considered the Geology,Geochemistry and Geochronology of the different units of Rocha Formation

Chronostratigraphy in karst records from the Epipaleolithic to the Mid/Early Neolithic (c. 13.0-6.0 cal ka BP) in the Catalan Coastal Ranges of NE Iberia: environmental changes, sedimentary processes and human activity

Science.gov (United States)

Bergadà, M. Mercè; Cervelló, Josep M.; Edo, Manel; Cebrià, Artur; Oms, F. Xavier; Martínez, Pablo; Antolín, Ferran; Morales, Juan Ignacio; Pedro, Mireia

2018-03-01

The stratigraphic, sedimentary and palaeoenvironmental features reflected in cavities in the Catalan Coastal Ranges of NE Iberia (Can Sadurní and Guineu caves) characterize the periods of pronounced climatic and human complexity that occurred c. 13.0-6.0 cal ka BP. This includes the stages of the Younger Dryas and Mid/Early Holocene, the latter being one of the periods of so-called Rapid Climatic Changes (RCCs). These caves, like others in Mediterranean contexts, are the result of an old duct originating in the saturated zone of the karst system and open to the outside; recording a succession of different detrital and anthropic episodes of the Epipaleolithic, Mesolithic and Neolithic communities. From this study it can be seen that paleoclimatic events do not always present clear signals in the karst records, especially c. 12.7-7.4 cal ka BP, corresponding to the Epipaleolithic and Mesolithic. It is characterized by a stratigraphic discontinuity in which there are phases with predominantly detrital sedimentation alternating with hiatus intervals. Detrital sedimentation formed by fine material colluvium with gravitational movements or solifluction processes in fresh and humid conditions. It appears in the following chronological intervals: 12.7-12.2 cal ka BP, 11.5/11.1-10.7/10.4 cal ka BP and 8.2-8.0 cal ka BP (less humid). Hiatus phases are represented in the rest of the sequence up to c. 7.4 cal ka BP. From the sedimentary point of view these stages of hiatus are indicative of phases of stability or lack of episodes with seasonal contrasts; a fact that would cause interruptions to detrital deposition in the interior of the caves. In contrast, in the period c. 7.4 to 6.0 cal ka BP, attributed to the Middle and Early Neolithic, there is a certain stratigraphic continuity. From the sedimentary point of view it is distinguished by a variability of processes that responds to accumulative episodes of short duration characteristic of morphogenesis of the slopes in an

Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

Directory of Open Access Journals (Sweden)

P. Kraal

2012-07-01

Full Text Available In this study, we investigate phosphorus (P and iron (Fe cycling in sediments along a depth transect from within to well below the oxygen minimum zone (OMZ in the northern Arabian Sea (Murray Ridge. Pore-water and solid-phase analyses show that authigenic formation of calcium phosphate minerals (Ca-P is largely restricted to where the OMZ intersects the seafloor topography, likely due to higher depositional fluxes of reactive P. Nonetheless, increased ratios of organic carbon to organic P (C_org/P_org and to total reactive P (C_org/P_reactive in surface sediments indicate that the overall burial efficiency of P relative to C_org decreases under the low bottom water oxygen concentrations (BWO in the OMZ. The relatively constant Fe/Al ratio in surface sediments along the depth transect suggest that corresponding changes in Fe burial are limited. Sedimentary pyrite contents are low throughout the ~25 cm sediment cores at most stations, as commonly observed in the Arabian Sea OMZ. However, pyrite is an important sink for reactive Fe at one station in the OMZ. A reactive transport model (RTM was applied to quantitatively investigate P and Fe diagenesis at an intermediate station at the lower boundary of the OMZ (bottom water O₂: ~14 μmol L⁻¹. The RTM results contrast with earlier findings in showing that Fe redox cycling can control authigenic apatite formation and P burial in Arabian Sea sediment. In addition, results suggest that a large fraction of the sedimentary Ca-P is not authigenic, but is instead deposited from the water column and buried. Dust is likely a major source of this Ca-P. Inclusion of the unreactive Ca-P pool in the C_org/P ratio leads to an overestimation of the burial efficiency of reactive P relative to C_org along the depth transect. Moreover, the unreactive Ca-P accounts for ~85% of total Ca-P burial. In general, our results reveal

Laboratory simulated hydrothermal alteration of sedimentary organic matter from Guaymas Basin, Gulf of California. Ph.D. Thesis

Science.gov (United States)

Leif, Roald N.

1993-01-01

High temperature alteration of sedimentary organic matter associated with marine hydrothermal systems involves complex physical and chemical processes that are not easily measured in most natural systems. Many of these processes can be evaluated indirectly by examining the geochemistry of the hydrothermal system in the laboratory. In this investigation, an experimental organic geochemical approach to studying pyrolysis of sedimentary organic matter is applied to the hydrothermal system in the Guaymas Basin, Gulf of California. A general survey of hydrothermal oils and extractable organic matter (bitumen) in hydrothermally altered sediments identified several homologous series of alkanones associated with a high temperature hydrothermal origin. The alkanones range in carbon number from C11 to C30 with no carbon number preference. Alkan-2-ones are in highest concentrations, with lower amounts of 3-, 4-, 5- (and higher) homologs. The alkanones appear to be pyrolysis products synthesized under extreme hydrothermal conditions. Hydrous pyrolysis and confinement pyrolysis experiments were performed to simulate thermally enhanced diagenetic and catagenetic changes in the immature sedimentary organic matter. The extent of alteration was measured by monitoring the n-alkanes, acyclic isoprenoids, steroid and triterpenoid biomarkers, polycyclic aromatic hydrocarbons and alkanones. The results were compared to bitumen extracts from sediments which have been naturally altered by a sill intrusion and accompanied hydrothermal fluid flow. These pyrolysis experiments duplicated many of the organic matter transformations observed in the natural system. Full hopane and sterane maturation occurred after 48 hr in experiments at 330 deg C with low water/rock mass ratios (0.29). A variety of radical and ionic reactions are responsible for the organic compound conversions which occur under extreme hydrothermal conditions. Short duration pyrolysis experiments revealed that a portion of the

A geologic approach to field methods in fluvial geomorphology

Science.gov (United States)

Fitzpatrick, Faith A.; Thornbush, Mary J; Allen, Casey D; Fitzpatrick, Faith A.

2014-01-01

A geologic approach to field methods in fluvial geomorphology is useful for understanding causes and consequences of past, present, and possible future perturbations in river behavior and floodplain dynamics. Field methods include characterizing river planform and morphology changes and floodplain sedimentary sequences over long periods of time along a longitudinal river continuum. Techniques include topographic and bathymetric surveying of fluvial landforms in valley bottoms and describing floodplain sedimentary sequences through coring, trenching, and examining pits and exposures. Historical sediment budgets that include floodplain sedimentary records can characterize past and present sources and sinks of sediment along a longitudinal river continuum. Describing paleochannels and floodplain vertical accretion deposits, estimating long-term sedimentation rates, and constructing historical sediment budgets can assist in management of aquatic resources, habitat, sedimentation, and flooding issues.

Use of variations in unit cell length, reflectance and hardness for determining the origin of Fe disulphides in sedimentary rocks

Science.gov (United States)

Dill, H. G.; Eberhard, E.; Hartmann, B.

1997-01-01

Fe disulphides are common opaque accessories in sedimentary rocks. Both marcasite and pyrite may shed some light on the depositional environment and help determine the diagenesis of their host rocks. Quantitative ore microscopy (reflectance measurements, Vickers hardness numbers) and X-ray diffraction methods, supplemented with scanning electron microscopy and chemical analyses, were applied to pyrite (and some marcasite) hosted by sedimentary rocks spanning the interval from the Devonian to the Pliocene, and formed in various marine and continental environments. Quantitative ore microscopy of pyrites of sedimentary origin does not seem to be an efficient tool for analyzing the environment owing to the inhomogeneous nature of sulphide aggregates when viewed under the ore microscope, and the variable amounts of minor elements (e.g., As, Ni, and Co) that control the reflectance values (RV) and Vickers hardness numbers (VHN) of the host sulphides. However, such parameters as crystal habit and unit cell length of pyrite, which correlate with FeS x, are useful for environmental analysis. The redox conditions and the presence of organic remains during formation are the main factors determining these crystallographic parameters. Differences in these parameters from those of pure, ideal FeS 2 can be related to substitution of, e.g., wustite in the pyrite lattice, reflecting moderate oxidation (i.e. in the microenvironment). As far as crystal habit and length of the cell edge are concerned, late stage diagenesis is obviously less important than the microenvironment attending initial formation. The environment of deposition (i.e. the macroenvironment) of pyrite-bearing rocks has no influence on the crystal morphology or the length of the unit cell of Fe disulphide. X-ray diffraction measurements demonstrate that this method provides useful evidence on the microenvironment of sulphide precipitation around a single, equant pyrite, as well as around pyritized fossils.

Igneous-sedimentary petroleum systems; Sistemas petroliferos igneo-sedimentares

Energy Technology Data Exchange (ETDEWEB)

Eiras, Jaime Fernandes [Para Univ., Belem, PA (Brazil)]. E-mail: eiras@ufpa.br; Wanderley Filho, Joaquim Ribeiro [PETROBRAS S.A., Manaus, AM (Brazil). Unidade de Negocios-BSOL]. E-mail: jwand@petrobras.com.br

2003-07-01

Igneous-sedimentary petroleum systems are mixed systems in which one or more essential elements or processes are related to magmatic events. Many examples worldwide are presented to show the importance of igneous rocks in the exploratory activities, as well as in the petroleum occurrence. Volcanic ash layers are of great importance in stratigraphic correlation and elucidation of structures, particularly when they occur in thick nonfossiliferous strata. They are also good indicators of turbidite deposition where turbidity currents are related to earthquakes generated by magmatic events. Unconventional reservoirs can be created by volcanic eruptions or intrusions, crystallization, reworking, and fracturing. Unaltered igneous rocks can seal vertically and laterally conventional reservoirs due to its excellent cap capacity. Abnormal thermal effect of igneous rocks can compensate the lack of overburden in shallow basins. Structural or combined traps can be formed due to intrusions, such as folded, faulted, and unconformity traps. Porosity can be either primary or secondary, or both. Primary porosity mainly consists of cavities produced by gas volatilization during eruption and cooling. Secondary porosity refers to those pores that result from hydrothermal alteration, recrystallization, and dissolution by groundwater, and tectonic stress. It includes intercrystalline pores formed by crystallization of various secondary minerals, dissolution pores, and tectonic fractures. New technologies of petroleum development and production are encouraging to search for oil and gas within igneous rocks, and new discoveries are expected. (author)

Levels and ages of selenium and metals in sedimentary cores of Ise Bay as determined by 210-Pb dating technique

International Nuclear Information System (INIS)

Itoh, K.; Chikuma, M.; Tanaka, H.

1987-01-01

Ise Bay is connected with estuaries of Nagoya harbor which is one of the most active industrial areas in Japan. Nagoya harbor estuaries are recipient of a large quantity of municipal and industrial discharge. The land boundaries of estuaries are sites of the manufacturing industries and they are utilized by oil tankers and cargo vessels. Accumulation of various kinds of metal such as selenium, mercury, zinc, copper, lead, and chromium have occurred in sediments for many years. The authors have carried out an extensive investigation on the selenium pollution of sea water and sediments of Nagoya harbor estuaries. The input of selenium to Ise Bay has occurred ever since the industrial activity was established in Nagoya city. Investigators have reported the sedimentary record of metals of Tokyo Bay, Osaka Bay and Seto Inland Sea. Some investigators reported the pollution caused by polynuclear aromatic hydrocarbon in sediments of Ise Bay, but did not mention metals. The authors determined metals including selenium in sedimentary core samples. The ages of those samples were already estimated by 210-Pb dating technique

Sedimentary characteristics and controlling factors of shelf sand ridges in the Pearl River Mouth Basin, northeast of South China Sea

Directory of Open Access Journals (Sweden)

Xiangtao Zhang

2017-04-01

Full Text Available Shelf sand ridge is a significant type of reservoir in the continental marginal basin, and it has drawn so much attention from sedimentologists and petroleum geologists. We were able to investigate the morphology, distribution, and sedimentary structures of shelf sand ridges systematically in this study based on the integration of high-resolution 3D seismic data, well logging, and cores. These shelf sand ridges are an asymmetrical mound-like structure in profiles, and they developed on an ancient uplift in the forced regression system tract and are onlapped by the overlying strata. In the plane, shelf sand ridges present as linear-shaped, which is different from the classical radial pattern; not to mention, they are separated into two parts by low amplitude tidal muddy channels. Corrugated bedding, tidal bedding, and scouring features are distinguished in cores of shelf sand ridges together with the coarsening up in lithology. All of these sedimentary characteristics indicate that shelf sand ridges deposited in the Pearl River Mouth Basin are reconstructed by the tidal and coastal current.

Collaborative Research: Bringing Problem Solving in the Field into the Classroom: Developing and Assessing Virtual Field Trips for Teaching Sedimentary and Introductory Geology

Science.gov (United States)

Wang, P.; Caldwell, M.

2012-12-01

Coastal Florida offers a unique setting for the facilitation of learning about a variety of modern sedimentary environments. Despite the conflicting concept of "virtual" and "actual" field trip, and the uncertainties associated with the implementation and effectiveness, virtual trips provide likely the only way to reach a large diversified student population and eliminate travel time and expenses. In addition, with rapidly improving web and visualization technology, field trips can be simulated virtually. It is therefore essential to systematically develop and assess the educational effectiveness of virtual field trips. This project is developing, implementing, and assessing a series of virtual field trips for teaching undergraduate sedimentary geology at a large four-year research university and introductory geology at a large two-year community college. The virtual field trip is based on a four-day actual field trip for a senior level sedimentary geology class. Two versions of the virtual field trip, one for advanced class and one for introductory class, are being produced. The educational outcome of the virtual field trip will be compared to that from actual field trip. This presentation summarizes Year 1 achievements of the three-year project. The filming, editing, and initial production of the virtual field trip have been completed. Formative assessments were conducted by the Coalition for Science Literacy at the University of South Florida. Once tested and refined, the virtual field trips will be disseminated through broadly used web portals and workshops at regional and national meetings.

15N/14N variations in Cretaceous Atlantic sedimentary sequences: implication for past changes in marine nitrogen biogeochemistry

Science.gov (United States)

Rau, G.H.; Arthur, M.A.; Dean, W.E.

1987-01-01

At two locations in the Atlantic Ocean (DSDP Sites 367 and 530) early to middle Cretaceous organic-carbon-rich beds ("black shales") were found to have significantly lower ??15N values (lower 15N/14N ratios) than adjacent organic-carbon-poor beds (white limestones or green claystones). While these lithologies are of marine origin, the black strata in particular have ??15N values that are significantly lower than those previously found in the marine sediment record and most contemporary marine nitrogen pools. In contrast, black, organic-carbon-rich beds at a third site (DSDP Site 603) contain predominantly terrestrial organic matter and have C- and N-isotopic compositions similar to organic matter of modern terrestrial origin. The recurring 15N depletion in the marine-derived Cretaceous sequences prove that the nitrogen they contain is the end result of an episodic and atypical biogeochemistry. Existing isotopic and other data indicate that the low 15N relative abundance is the consequence of pelagic rather than post-depositional processes. Reduced ocean circulation, increased denitrification, and, hence, reduced euphotic zone nitrate availability may have led to Cretaceous phytoplankton assemblages that were periodically dominated by N2-fixing blue-green algae, a possible source of this sediment 15N-depletion. Lack of parallel isotopic shifts in Cretaceous terrestrially-derived nitrogen (Site 603) argues that the above change in nitrogen cycling during this period did not extend beyond the marine environment. ?? 1987.

Sedimentary facies and depositional environments of early Mesozoic Newark Supergroup basins, eastern North America

Science.gov (United States)

Smoot, J.P.

1991-01-01

The early Mesozoic Newark Supergroup consists of continental sedimentary rocks and basalt flows that occupy a NE-trending belt of elongate basins exposed in eastern North America. The basins were filled over a period of 30-40 m.y. spanning the Late Triassic to Early Jurassic, prior to the opening of the north Atlantic Ocean. The sedimentary rocks are here divided into four principal lithofacies. The alluvial-fan facies includes deposits dominated by: (1) debris flows; (2) shallow braided streams; (3) deeper braided streams (with trough crossbeds); or (4) intense bioturbation or hyperconcentrated flows (tabular, unstratified muddy sandstone). The fluvial facies include deposits of: (1) shallow, ephemeral braided streams; (2) deeper, flashflooding, braided streams (with poor sorting and crossbeds); (3) perennial braided rivers; (4) meandering rivers; (5) meandering streams (with high suspended loads); (6) overbank areas or local flood-plain lakes; or (7) local streams and/or colluvium. The lacustrine facies includes deposits of: (1) deep perennial lakes; (2) shallow perennial lakes; (3) shallow ephemeral lakes; (4) playa dry mudflats; (5) salt-encrusted saline mudflats; or (6) vegetated mudflats. The lake margin clastic facies includes deposits of: (1) birdfoot deltas; (2) stacked Gilbert-type deltas; (3) sheet deltas; (4) wave-reworked alluvial fans; or (5) wave-sorted sand sheets. Coal deposits are present in the lake margin clastic and the lacustrine facies of Carnian age (Late Triassic) only in basins of south-central Virginia and North and South Carolina. Eolian deposits are known only from the basins in Nova Scotia and Connecticut. Evaporites (and their pseudomorphs) occur mainly in the northern basins as deposits of saline soils and less commonly of saline lakes, and some evaporite and alkaline minerals present in the Mesozoic rocks may be a result of later diagenesis. These relationships suggest climatic variations across paleolatitudes, more humid to the

Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis

Energy Technology Data Exchange (ETDEWEB)

Díaz-de-Alba, Margarita [Department of Analytical Chemistry, Institute of Biomolecules (INBIO), Faculty of Sciences, CEI-MAR, University of Cadiz, Campus Rio S. Pedro, E-11510, Puerto Real, Cadiz (Spain); Huerta-Diaz, Miguel Angel, E-mail: huertam@uabc.edu.mx [Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California (Mexico); Delgadillo-Hinojosa, Francisco [Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California (Mexico); Hare, Landis [Centre Eau Terre Environnement, 490, rue de la Couronne, Québec, Québec G1K 9A9 (Canada); Galindo-Riaño, M. Dolores [Department of Analytical Chemistry, Institute of Biomolecules (INBIO), Faculty of Sciences, CEI-MAR, University of Cadiz, Campus Rio S. Pedro, E-11510, Puerto Real, Cadiz (Spain); Siqueiros-Valencia, Arturo [Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California (Mexico)

2016-02-01

Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) > 80% in both harbors. Dissolved Fe flux measurements combined with solid phase Fe sulfide data indicated that 98 mt of Fe are precipitated as iron sulfides every year in Ensenada Harbor. These Fe sulfides (and associated trace metals) will remain preserved in the sediments, unless they are perturbed by dredging or sediment resuspension. Calculations indicate that dredging activities could export to the open ocean 0.20 ± 0.13 to (0.30 ± 0.56) × 10{sup 3} mt of Cd and Cu, respectively, creating a potential threat to marine benthic organisms. Degrees of pyritization (DOP) values in Ensenada and El Sauzal harbors were relatively low (< 25%) while degrees of sulfidization (DOS) were high (~ 50%) because of the contribution of acid volatile sulfide. DOP values correlated with DTMP values (p ≤ 0.001), indicating that metals are gradually incorporated into pyrite as this mineral is formed. Significant correlations were also found between DTMP values and − log(K{sub sp(MeS)}/K{sub sp(pyr)}) for both harbors, indicating that incorporation of trace metals into the pyrite phase is a function of the solubility product of the corresponding metal sulfide. The order in which elements were pyritized in both harbors was Zn ≈ Mn < Fe < Cd ≈ Pb < Ni ≈ Co < < Cu. Lastly, a strong correlation (r{sup 2} = 0.87, p < 0.01) was found between average reactive trace metal concentrations and metal concentrations measured in Armandia brevis (a deposit-feeding Opheliid polychaete), suggesting that these labile sedimentary metals are

Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis

International Nuclear Information System (INIS)

Díaz-de-Alba, Margarita; Huerta-Diaz, Miguel Angel; Delgadillo-Hinojosa, Francisco; Hare, Landis; Galindo-Riaño, M. Dolores; Siqueiros-Valencia, Arturo

2016-01-01

Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) > 80% in both harbors. Dissolved Fe flux measurements combined with solid phase Fe sulfide data indicated that 98 mt of Fe are precipitated as iron sulfides every year in Ensenada Harbor. These Fe sulfides (and associated trace metals) will remain preserved in the sediments, unless they are perturbed by dredging or sediment resuspension. Calculations indicate that dredging activities could export to the open ocean 0.20 ± 0.13 to (0.30 ± 0.56) × 10"3 mt of Cd and Cu, respectively, creating a potential threat to marine benthic organisms. Degrees of pyritization (DOP) values in Ensenada and El Sauzal harbors were relatively low (< 25%) while degrees of sulfidization (DOS) were high (~ 50%) because of the contribution of acid volatile sulfide. DOP values correlated with DTMP values (p ≤ 0.001), indicating that metals are gradually incorporated into pyrite as this mineral is formed. Significant correlations were also found between DTMP values and − log(K_s_p_(_M_e_S_)/K_s_p_(_p_y_r_)) for both harbors, indicating that incorporation of trace metals into the pyrite phase is a function of the solubility product of the corresponding metal sulfide. The order in which elements were pyritized in both harbors was Zn ≈ Mn < Fe < Cd ≈ Pb < Ni ≈ Co < < Cu. Lastly, a strong correlation (r"2 = 0.87, p < 0.01) was found between average reactive trace metal concentrations and metal concentrations measured in Armandia brevis (a deposit-feeding Opheliid polychaete), suggesting that these labile sedimentary metals are

The geological and microbiological controls on the enrichment of Se and Te in sedimentary rocks

Science.gov (United States)

Bullock, Liam; Parnell, John; Armstrong, Joseph; Boyce, Adrian; Perez, Magali

2017-04-01

Selenium (Se) and tellurium (Te) have become elements of high interest, mainly due to their photovoltaic and photoconductive properties, and can contaminate local soils and groundwater systems during mobilisation. Due to their economic and environmental significance, it is important to understand the processes that lead to Se- and Te-enrichment in sediments. The distribution of Se and Te in sedimentary environments is primarily a function of redox conditions, and may be transported and concentrated by the movement of reduced fluids through oxidised strata. Se and Te concentrations have been measured in a suite of late Neoproterozoic Gwna Group black shales (UK) and uranium red bed (roll-front) samples (USA). Due to the chemical affinity of Se and sulphur (S), variations in the S isotopic composition of pyrite have also been measured in order to provide insights into their origin. Scanning electron microscopy of pyrite in the black shales shows abundant inclusions of the lead selenide mineral clausthalite. The data for the black shale samples show marked enrichment in Te and Se relative to crustal mean and several hundreds of other samples processed through our laboratory. While Se levels in sulphidic black shales are typically below 5 ppm, the measured values of up to 116 ppm are remarkable. The Se enrichment in roll-fronts (up to 168 ppm) is restricted to a narrow band of alteration at the interface between the barren oxidised core, and the highly mineralised reduced nose of the front. Te is depleted in roll-fronts with respect to the continental crust and other geological settings and deposits. S isotope compositions for pyrite in both the black shales and roll-fronts are very light and indicate precipitation by microbial sulphate reduction, suggesting that Se was microbially sequestered. Results show that Gwna Group black shales and U.S roll-front deposits contain marked elemental enrichments (particularly Se content). In Gwna Group black shales, Se and Te were

BIO-SEDIMENTARY SIGNATURES OF HIGH-FREQUENCY SALINITY/SUBAERIAL EXPOSURE CHANGES: EXAMPLES FROM THE OXFORDIAN OF PORTUGAL (CABAÇOS FORMATION

Directory of Open Access Journals (Sweden)

ANA C. AZERÊDO

2004-03-01

Full Text Available The detailed sedimentary and micropalaeontological analysis of a complex association of continental to marginal-marine deposits from the Oxfordian of Portugal (Cabaços Formation has allowed the recognition of high-frequency, subtle changes in the environmental conditions. The main factors controlling the palaeobiological responses to such minor-scale fluctuations were also identified. Two factors have shown to be especially significant: subaerial exposure duration and frequency (estimated by assigning type of features to the exposure index and salinity trends, as suggested by the sedimentary and fossil records. In the west of the basin, salinity fluctuations were much stronger and more frequent (fresh- brackish-restricted marine-hypersaline, and subaerial exposure more marked for longer periods, than in the east of the basin. The microfossil assemblages, as a whole, but in particular the ostracod faunas, show differences in abundance, diversity, dominant species, degree of intrageneric and intraspecific variations, both along the successions and between west and east. The western populations seem to have been much less stable, which suggests that high-frequency changes in salinity (more than its absolute values and degree of exposure were the most important controls on the palaeobiota. PDF

Study on characteristics of sedimentary rock at the Horonobe site. Report of collaboration research between CRIEPI and JAEA

International Nuclear Information System (INIS)

Kiho, Kenzo; Oyama, Takahiro; Suzuki, Koichi; Nakata, Eiji; Tanaka, Shiro; Miyakawa, Kimio; Ishii, Eiichi; Takahashi, Kazuharu; Kunimaru, Takanori; Tsukui, Rota; Fukushima, Tatsuo; Seya, Masami; Hama, Katsuhiro; Aoki, Kazuhiro

2006-01-01

CRIEPI (Central Research Institute of Electric Power Industry) and JAEA (Japan Atomic Energy Agency) have been conducting a collaboration research to develop methodology for the characterization of geological environment since FY 2002. This report describes the results of the collaboration research in mainly FY 2003. As the collaboration research, the following research results were obtained. (1) Study on the diagenesis of the sedimentary rock of the Noegene Tertiary. The maximum burial depth of the formation can be estimated. (2) Study on the chemical weathering of the soft sedimentary rock. The acidic water can be caused by the chemical weathering of the rock in the Koetoi formation. (3) Study on the pore water extraction. The hydrochemical condition at the Horonobe site can be estimated by the results of the chemical analyses of extracted pore water, and the different pressure of the extraction results the different chloride contents of the pore water. (4) Study on exploration method considering the physical property of the rock. The depth profile of the mechanical properties can be estimated by the results of physical logging in the borehole. (5) Study on the applicability of the controlled drilling system to the Horonobe site. The controlled drilling system can be applicable to drill the directional borehole. (author)

Regional stratigraphy, sedimentology, and tectonic significance of Oligocene-Miocene sedimentary and volcanic rocks, northern Baja California, Mexico

Science.gov (United States)

Dorsey, Rebecca J.; Burns, Beverly

1994-01-01

Upper Oligocene (?) to middle Miocene sedimentary and volcanic rocks in northern Baja California were deposited along the western margin of North America during subduction of the Guadalupe plate and southward migration of the Rivera Triple Junction. Regional mapping and compilation of stratigraphic data reveal a sequence of three regionally traceable stratigraphic units. (1) Oligocene (?) to lower Miocene Mesa Formation: basal quartz-rich fluvial sandstone, grus, conglomerate, and accessory facies, whose detrital compositions reflect the composition of local pre-Tertiary basement rock. (2) Lower to middle Miocene Comondú Formation: laterally variable sequence of volcaniclastic conglomerate, breccia, sandstone, tuff and minor volcanic flow units. (3) Widespread mesa-capping rhyolite tuff, typically welded and crystal-rich, probably upper Miocene in age. The Mesa Formation overlies a highly irregular and deeply dissected erosional surface developed on pre-Tertiary basement rock. The shift from pre-Mesa erosion to widespread (though localized) deposition and valley-filling records the final phase of late Cretaceous to middle Tertiary regional subsidence and eastward transgression that resulted from slow cooling and thermal contraction of Cretaceous arc crust during a temporal gap in magmatic activity along the western Cordilleran margin. Nonmarine sediments of the Mesa Formation were deposited in small, steep-walled paleovalleys and basins that gradually filled and evolved to form through-going, low-energy ephemeral stream systems. The gradational upward transition from the Mesa to Comondú Formation records the early to middle Miocene onset of subduction-related arc magmatism in eastern Baja California and related westward progradation of alluvial volcaniclastic aprons shed from high-standing eruptive volcanic centers. Pre-existing streams were choked with the new influx of volcanic detritus, causing the onset of rapid sediment deposition by stream flows and dilute

Late Pleistocene lithostratigraphy and sequences in the southwestern Mesopotamia (Argentina): Evidences of the last interglacial stage

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Ernesto, Brunetto; Soledad, Ferrero Brenda; Ignacio, Noriega Jorge

2015-03-01

The aim of this paper is to show the stratigraphic record of the Late Pleistocene corresponding to the distal region of the Paraná River basin. It displays sedimentological, paleontological and geochronological evidences that characterise the last interglacial-glacial cycle. In particular, strong environmental records are shown for the Last Interglacial Stage (LIS). Salto Ander Egg Formation (SAEF) is defined as a new lithostratigraphic unit representative of the Late Pleistocene in southwestern Mesopotamia. This unit is formed of complex fluvial deposits, which contains a heterogeneous collection of sub-environments, of ages ranging from 120 to 60 ky BP. The clast-supported gravel facies containing sparse boulders indicate high flow during a humid climate. The large and middle-scale architectures of fluvial sedimentary bodies evidence the relationship between the sediment accommodation and the sea level oscillations. Three sub-sequences identified in the succession suggest a transgressive trend during the MIS5e, a highstand stage in MIS5c, and a minor transgressive cycle during MIS3. A Brazilian faunal association collected at the bottom of the sequence and sedimentological interpretations display wet and warm climatic conditions, typical of tropical or subtropical environments. Such environmental conditions are characteristic of the maximum of the last interglacial stage (MIS5e) and show a signal stronger than the signal of the current interglacial stage. All these data show a direct correlation between the increases of paleodischarges and the elevation of the sea level. The whole sequence is completed with transitional swampy deposits, accumulated probably during the MIS3/MIS2 transition, and the typical loess of the Tezanos Pinto Formation, mantled during the Last Maximum Glacial.

Ferroan dolomite cement in Cambrian sandstones: burial history and hydrocarbon generation of the Baltic sedimentary basin

DEFF Research Database (Denmark)

Sliaupa, S.; Cyziene, J.; Molenaar, Nicolaas

2008-01-01

The conditions and timing of carbonate cementation in Cambrian sandstones of the Baltic sedimentary basin were determined by oxygen and carbon stable isotope and chemical data in combination with optical and cathodoluminescence petrographic studies. Studied samples represent a range in present...... burial depth from 340 to 2150 m. The carbonate cement is dominantly ferroan dolomite that occurs as dispersed patches of poikilotopic crystals. Temperatures of dolomite precipitation, based on delta O-18 values, range from 27 degrees C in the shallow buried to 95 degrees C in the deep buried sandstones...

Volcaniclastic and sedimentary deposits in Late Oligocene/Early Miocene Smrekovec Volcanic Complex, northern Slovenia

Science.gov (United States)

Kralj, Polona

2010-05-01

Late Oligocene/Early Miocene volcanic activity in northern Slovenia is related to post-collisional accommodation of continental Apulian and oceanic European plates (von Blanckenburg and Davis, 1996). It occurred in one of small south-western marginal depressions of the Pannonian basin system, locally termed the Smrekovec Basin (Hanfland et al., 2004). Contemporaneous clastic sedimentation is evidenced by several hundred metres thick succession composed mainly of mudstone, siltstone and sand. Smrekovec Volcanic Complex (SVC) is an eroded and tectonically uplifted remain of a larger submarine stratovolcano edifice, built of lavas, shallow or subsurface intrusive bodies, and pyroclastic, hyaloclastic, syn-eruptively resedimented volcaniclastic and reworked volcaniclastic-sedimentary deposits (Kralj, 1996). The development of lithofacies of syn-eruptively resedimented deposits is controlled by the proximity to the ancient volcano summit and the volcano sloping. Moreover, close to the rising volcano edifice, distinct shallow-water environments with siliciclastic sedimentation developed. Syn-eruptively resedimented deposits are the most widespread and are related to volcaniclastic debris flows and volcaniclastic tubidity flows. Volcaniclastic debris flow deposits are subdivided into lithofacies Bx - polymict volcaniclastic breccia, and Bt - volcaniclastic tuff-breccia. Bx occurs as tabular, up to some ten metres thick bodies with abundant up to 5 dm large angular lava clasts and angular or rounded clasts of fine-grained tuff, and tuffaceous matrix. Bt forms basal, massive layers in fining-upward sequences. The main constituent is tuffaceous matrix; up to 1.5 dm large clasts of lavas and tuffs are subordinate. In a distance up to 2 km from the former volcano summit (proximal area), Bt predominates in the sequence lithofacies composition (~75 %), and attains a thickness of up to 4 m. At a distance of 2-4 km (distal area), a maximum Bt thickness rarely exceeds 5 dm, an

The Impact of the 1989 Exxon Valdez Oil Spill on Phytoplankton as Evidenced Through the Sedimentary Dinoflagellate Cyst Records in Prince William Sound (Alaska, USA).

Science.gov (United States)

Genest, M.; Pospelova, V.; Williams, J. R.; Dellapenna, T.; Mertens, K.; Kuehl, S. A.

2016-12-01

Large volumes of crude oil are extracted from marine environments and transported via the sea, putting coastal communities at a greater risk of oils spills. It is therefore crucial for these communities to properly assess the risk. The first step is to understand the effects of such events on the environment, which is limited by the lack of research on the impact of oil spills on phytoplankton. This first-of-its-kind research aims to identify how one of the major groups of phytoplankton, dinoflagellates, have been affected by the 1989 Exxon Valdez oil spill in Prince William Sound (PWS), Alaska. To do this, sedimentary records of dinoflagellate cysts, produced during dinoflagellate reproduction and preserved in the sediment, were analyzed. Two sediment cores were collected from PWS in 2012. The sediments are mainly composed of silt with a small fraction of clay. Both well-dated with 210Pb and 137Cs, the cores have high sedimentation rates, allowing for an annual to biannual resolution. Core 10 has a sedimentation rate of 1.1 cm yr-1 and provides continuous record since 1957, while Core 12 has a sedimentation rate of 1.3 cm yr-1 and spans from 1934. The cores were subsampled every centimeter for a total of 110 samples. Samples were treated using a standard palynological processing technique to extract dinoflagellate cysts and 300 cysts were counted per sample. In both cores, cysts were abundant, diverse and well preserved with the average cyst assemblage being characterized by an equal number of cysts produced by autotrophic and heterotrophic dinoflagellates. Of the 40 dinoflagellate cyst taxa, the most abundant are: Operculodinium centrocarpum and Brigantedinium spp. Other common species are: Spiniferites ramosus, cysts of Pentapharsodinium dalei, Echinidinium delicatum, E. zonneveldiae, E. transparantum, Islandinium minutum, and a thin pale brown Brigantedinium type. Changes in the sedimentary sequence of dinoflagellate cysts were analyzed by determining cyst

Quantum-Sequencing: Fast electronic single DNA molecule sequencing

Science.gov (United States)

Casamada Ribot, Josep; Chatterjee, Anushree; Nagpal, Prashant

2014-03-01

A major goal of third-generation sequencing technologies is to develop a fast, reliable, enzyme-free, high-throughput and cost-effective, single-molecule sequencing method. Here, we present the first demonstration of unique ``electronic fingerprint'' of all nucleotides (A, G, T, C), with single-molecule DNA sequencing, using Quantum-tunneling Sequencing (Q-Seq) at room temperature. We show that the electronic state of the nucleobases shift depending on the pH, with most distinct states identified at acidic pH. We also demonstrate identification of single nucleotide modifications (methylation here). Using these unique electronic fingerprints (or tunneling data), we report a partial sequence of beta lactamase (bla) gene, which encodes resistance to beta-lactam antibiotics, with over 95% success rate. These results highlight the potential of Q-Seq as a robust technique for next-generation sequencing.

The relation between well spacing and Net Present Value in fluvial Hot Sedimentary Aquifer geothermal doublets : a West Netherlands Basin case study

NARCIS (Netherlands)

Willems, C.J.L.; Goense, T.; Maghami Nick, Hamidreza M.; Bruhn, D.F.

2016-01-01

This paper analyzes the relation between well spacing and Net Present Value of a Hot Sedimentary Aquifer geothermal doublet. First, a sensitivity analysis is carried out to evaluate the effect of uncertainty of geological and production parameters on the Net present Value. Second a finite-element

Dolomitization and sedimentary cyclicity of the Ordovician, Silurian, and Devonian rocks in South Estonia

Directory of Open Access Journals (Sweden)

Kallaste, Toivo

2006-03-01

Full Text Available The distribution and composition of dolomitized rocks and stoichiometry of dolomite in southern Estonia in the Ordovician, Silurian, and Devonian were studied on the background of the facies, sedimentary cyclicity (nine shallowing-up cycles, and evolution of the palaeobasins. The composition of rocks and lattice parameters of dolomite were investigated using the X-ray diffraction, X-ray fluorescence, titration and gravimetric analyses, and porosity measurements. The formation of dolostones is directly determined by the cyclic evolution of palaeobasins. Dolomitized rocks belong to the shallow-water inner shelf or tidal/lagoonal facies belt of regressive phases of sedimentary cycles. Sediments of the deep shelf/transitional environment and transgressive phases are not dolomitized. The most stoichiometric is secondary replacive dolomite of Silurian and upper Ordovician dolostones, formed during the early diagenesis of normal-marine (saline shallow-shelf calcitic sediments. The content of insoluble residue does not affect the stoichiometry. The changes in lattice parameters are induced by the Ca/Mg ratio in the dolomite lattice. The dolomite of the dolostones contacting limestone or containing calcite has an expanded lattice. The primary (syngenetic dolostone of the lagoonal or tidal flat belt has also an expanded lattice. No dolomitizing effect of the waters of the Devonian palaeobasin on the underlying rocks was revealed. The whole data set of the studied dolostones is consistent with the marine water environment in the palaeobasin at the corresponding time and shows no sign of the inflow of external fluids. It suggests that the microbial model of dolomite formation may characterize the Ordovician, Silurian, and Devonian in southern Estonia. The occurrence of dolostones between undolomitized rocks limits the time of dolomitization to the early diagenetic stage.

Radon and its decay product activities in the magmatic area and the adjacent volcano-sedimentary Intrasudetic Basin

OpenAIRE

Solecki, A. T.; Puchala, R.; Tchorz, D.

2007-01-01

In the magmatic area of Sudetes covering the Karkonosze granite and adjacent volcano-sedimentary Intrasudetic Basin a study of atmospheric radon activity was performed by means of SSNTD Kodak LR-115. The study was completed by gamma spectrometric survey of eU and eTh determined by gamma activity of radon decay products 214Bi and 208Tl respectively. In the case of the western part of the Karkonosze granite area the radon decay products activity in the granitic basement was ...

Morphodynamics, sedimentary and anthropogenic influences in the San Vicente de la Barquera estuary (North coast of Spain)

OpenAIRE

FLOR-BLANCO, G.; FLOR, G.; PANDO, L.; ABANADES, J.

2015-01-01

The estuary of San Vicente de la Barquera (Cantabria, Spain) occupies two fluvial valleys that have incised into soft sedimentary rocks (Lower Mesozoic) and are controlled by inactive faults. These two estuary subsystems, the Escudo (main valley) and Gandarilla, share outer estuarine zones, i.e., a sandy bay and an estuary-mouth complex. The complexity of the system lies in the presence of a confining barrier formed by an aeolian dune/ beach system that is currently enclosed by a jetty, which...

Late Quaternary geomorphic history of a glacial landscape - new sedimentary and chronological data from the Cordillera de Cochabamba (Bolivia)

Science.gov (United States)

May, J.-H.; Preusser, F.; Zech, R.; Ilgner, J.; Veit, H.

2009-04-01

Throughout the Central Andes, glacial landscapes have long been used for the reconstruction of Late Quaternary glaciations and landscape evolution. Much work has focused on the Andes in Peru, Chile and the Bolivian Altiplano, whereas relatively little data has been published on glaciation history in the eastern Andean ranges and slopes. Even less is known with regard to the postglacial evolution of these glacial landscapes. In the Cordillera de Cochabamba (Bolivia), local maximum advances probably peaked around 20-25 ka BP and were followed by significant readvances between ~12-16 ka BP. This generally points to temperature controlled maximum glacial advances along the humid eastern slopes of the Central Andes, which is supported by glacier-climate-modelling studies. However, most studies include only marginal information with regard to the complex geomorphic and sedimentary situation in the Cordillera de Cochabamba. Furthermore, the chronological results are afflicted with several methodological uncertainties inherent to surface exposure dating and call for application of alternative, independent age dating methods. Therefore this study aims at i) documenting and interpreting the complex glacial geomorphology of the Huara Loma valley in the Cordillera de Cochabamba (Bolivia), ii) analyzing the involved units of glacial sediments, and iii) improving the chronological framework by applying optically stimulated luminescence (OSL) and radiocarbon dating (14C). For this purpose, geomorphic mapping was combined with field documentation of sedimentary profiles. The involved sediments were subject to geochemical and mineralogical analysis in order to deduce information on their erosional and weathering histories. In addition, the interpretation of OSL ages from glacial and proglacial sediments integrated several methodological procedures with regard to sample preparation and statistical analysis of the measurements in order to increase the degree of confidence. These

The mineralogy and petrology of I-type cosmic spherules: Implications for their sources, origins and identification in sedimentary rocks

Science.gov (United States)

Genge, Matthew J.; Davies, Bridie; Suttle, Martin D.; van Ginneken, Matthias; Tomkins, Andrew G.

2017-12-01

I-type cosmic spherules are micrometeorites that formed by melting during atmospheric entry and consist mainly of iron oxides and FeNi metal. I-types are important because they can readily be recovered from sedimentary rocks allowing study of solar system events over geological time. We report the results of a study of the mineralogy and petrology of 88 I-type cosmic spherules recovered from Antarctica in order to evaluate how they formed and evolved during atmospheric entry, to constrain the nature of their precursors and to establish rigorous criteria by which they may be conclusively identified within sediments and sedimentary rocks. Two textural types of I-type cosmic spherule are recognised: (1) metal bead-bearing (MET) spherules dominated by Ni-poor (100 and suggest that metal from H-group ordinary, CM, CR and iron meteorites may form the majority of particles. Oxidation during entry heating increases in the series MET 80 wt% Ni comprising a particle mass fraction of exchange of Ni between wüstite and metal, and magnetite and wüstite are suggested as proxies for the rate of oxidation and cooling rate respectively. Variations in magnetite and wüstite crystal sizes are also suggested to relate to cooling rate allowing relative entry angle of particles to be evaluated. The formation of secondary metal in the form of sub-micron Ni-rich or Pt-group nuggets and as symplectite with magnetite was also identified and suggested to occur largely due to the exsolution of metallic alloys during decomposition of non-stoichiometric wüstite. Weathering is restricted to replacement of metal by iron hydroxides. The following criteria are recommended for the conclusive identification of I-type spherules within sediments and sedimentary rocks: (i) spherical particle morphologies, (ii) dendritic crystal morphologies, (iii) the presence of wüstite and magnetite, (iv) Ni-bearing wüstite and magnetite, and (v) the presence of relict FeNi metal.

The NAA of trace elements and its application in the identification of the type of sedimentary organic matter

International Nuclear Information System (INIS)

Tong Chunhan; Li Guodong

1998-01-01

The type of sedimentary organic matter is an important parameter in evaluating an oil or gas field. Since the conventional organic geochemistry methods for determining the type meet unsurmountable difficulties when the maturity of organic matter is high, a new method to identify the type according to V and Ni contents in soluble organic matter based on NAA has been developed. Details of the method are introduced and an applied example is given

The Nysa-Morava Zone: an active tectonic domain with Late Cenozoic sedimentary grabens in the Western Carpathians' foreland (NE Bohemian Massif)

Czech Academy of Sciences Publication Activity Database

Špaček, P.; Bábek, O.; Štěpančíková, Petra; Švancara, J.; Pazdírková, J.; Sedláček, J.

2015-01-01

Roč. 104, č. 4 (2015), s. 963-990 ISSN 1437-3254 R&D Projects: GA ČR GAP210/12/0573; GA MŠk LM2010008 Institutional support: RVO:67985891 Keywords : Bohemian Massif * Upper Morava Basin * tectonic evolution * seismicity * sedimentary grabens Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.133, year: 2015

Multimodal sequence learning.

Science.gov (United States)

Kemény, Ferenc; Meier, Beat

2016-02-01

While sequence learning research models complex phenomena, previous studies have mostly focused on unimodal sequences. The goal of the current experiment is to put implicit sequence learning into a multimodal context: to test whether it can operate across different modalities. We used the Task Sequence Learning paradigm to test whether sequence learning varies across modalities, and whether participants are able to learn multimodal sequences. Our results show that implicit sequence learning is very similar regardless of the source modality. However, the presence of correlated task and response sequences was required for learning to take place. The experiment provides new evidence for implicit sequence learning of abstract conceptual representations. In general, the results suggest that correlated sequences are necessary for implicit sequence learning to occur. Moreover, they show that elements from different modalities can be automatically integrated into one unitary multimodal sequence. Copyright © 2015 Elsevier B.V. All rights reserved.

A comparison of sedimentary DNA and pollen from lake sediments in recording vegetation composition at the Siberian treeline.

Science.gov (United States)

Niemeyer, Bastian; Epp, Laura S; Stoof-Leichsenring, Kathleen R; Pestryakova, Luidmila A; Herzschuh, Ulrike

2017-11-01

Reliable information on past and present vegetation is important to project future changes, especially for rapidly transitioning areas such as the boreal treeline. To study past vegetation, pollen analysis is common, while current vegetation is usually assessed by field surveys. Application of detailed sedimentary DNA (sedDNA) records has the potential to enhance our understanding of vegetation changes, but studies systematically investigating the power of this proxy are rare to date. This study compares sedDNA metabarcoding and pollen records from surface sediments of 31 lakes along a north-south gradient of increasing forest cover in northern Siberia (Taymyr peninsula) with data from field surveys in the surroundings of the lakes. sedDNA metabarcoding recorded 114 plant taxa, about half of them to species level, while pollen analyses identified 43 taxa, both exceeding the 31 taxa found by vegetation field surveys. Increasing Larix percentages from north to south were consistently recorded by all three methods and principal component analyses based on percentage data of vegetation surveys and DNA sequences separated tundra from forested sites. Comparisons of the ordinations using procrustes and protest analyses show a significant fit among all compared pairs of records. Despite similarities of sedDNA and pollen records, certain idiosyncrasies, such as high percentages of Alnus and Betula in all pollen and high percentages of Salix in all sedDNA spectra, are observable. Our results from the tundra to single-tree tundra transition zone show that sedDNA analyses perform better than pollen in recording site-specific richness (i.e., presence/absence of taxa in the vicinity of the lake) and perform as well as pollen in tracing vegetation composition. © 2017 John Wiley & Sons Ltd.

Stepwise drowning of the urgonian carbonate platform and the sedimentary regime during the Mid-Cretaceous environmental crisis: new evidence from the Helvetic Alps

Science.gov (United States)

Linder, P.; Weissert, H.; Funk, H.; Föllmi, K. B.

2003-04-01

In the region of Anzeindaz (Ct. Vaud, Switzerland) the sedimentary succession of the so-called "Urgonian" of the Schrattenkalk Formation (late Barremian to early Aptian in age) and of the Garschella Formation (early Aptian to late Cenomanian in age) is well developed. These outcrops in the helvetic Morcles nappe are particularly appropriate to study the drowning events that lead to the disappearance of the urgonian carbonate platform and the subsequent development towards a sedimentary regime of condensation and authigenesis. Cavities with infillings of Garschella Formation sediments penetrating the Schrattenkalk limestone up to 20 meters deep are interpreted as karstic erosional cavities and/or neptunian dikes. The most interesting finding was the special way in which the drowning of the urgonian carbonate platform is documented. At one outcrop (La Corde) thin relics of a bed interpreted as the Upper Orbitolina Bed seem to be integrated in the Garschella Formation since it separates relics of at least two phosphoritic beds, probably the Luitere Bed but also an older bed that was not described by Föllmi and Ouwehand (1987). In fact a diploma student at the University of Neuchâtel, François Gainon (2001) just recently rediscovered and correctly interpreted a similar but less condensed succession in the nearby Rawil region that was first described (but misinterpreted) by Schaub (1936). Gainon named this older phosphoritic horizon of the Rawil region "Plaine Morte Bed" and he was able to date it with an ammonite of the earliest Aptian Weissi/Tuarkyricus Zones. In both the Rawil and Anzeindaz regions the whole ensemble is deposited over an erosive unconformity cutting off the Schrattenkalk limestone. The sedimentary succession of the Garschella Formation in the Anzeindaz region contains equivalents of nearly all beds described and defined in the type outcrops of eastern Switzerland and Austria (Föllmi &Ouwehand 1987). The study of these sediments revealed new

Criteria for the recognition and correlation of sandstone units in the Precambrian and Paleozoic-Mesozoic clastic sequence in the near east

Science.gov (United States)

Weissbrod, T.; Perath, I.

A systematic study of the Precambrian and Paleozoic-Mesozoic clastic sequences (Nubian Sandstone) in Israel and Sinai, and a comparative analysis of its stratigraphy in neighbouring countries, has shown that besides the conventional criteria of subdivision (lithology, field appearance, photogeological features, fossil content), additional criteria can be applied, which singly or in mutual conjuction enable the recognition of widespread units and boundaries. These criteria show lateral constancy, and recurrence of a similar vertical sequence over great distances, and are therefore acceptable for the identification of synchronous, region-wide sedimentary units (and consequently, major unconformities). They also enable, once the units are established, to identify detached (not in situ) samples, samples from isolated or discontinous outcrops, borehole material or archive material. The following rock properties were tested and found to be usefuls in stratigraphic interpretation, throughout large distribution areas of the clastic sequence: Landscape, which is basically the response of a particular textural-chemic al aggregate to atmospheric weathering. Characteristic outcrop feature — styles of roundness or massivity, fissuring or fliatin, slope profile, bedding — express a basic uniformity of these platform-type clastics. Colors are often stratigraphically constant over hundreds of kilometers, through various climates and topographies, and express some intrinsic unity of the rock bodies. Grain size and sorting, when cross-plotted, enable to differentiate existing unit. The method requires the analysis of representative numbers of samples. Vertical trends of median grain size and sorting show reversals, typically across unconformities. Feldstar content diminishes from 15-50% in Precambrian-Paleozoic rocks to a mere 5% or less in Mesozoic sandstones — a distinctive regionwide time trend. Dominance of certain feldstar types characterizes Precambrian and Paleozoic

Applying Binary Forecasting Approaches to Induced Seismicity in the Western Canada Sedimentary Basin

Science.gov (United States)

Kahue, R.; Shcherbakov, R.

2016-12-01

The Western Canada Sedimentary Basin has been chosen as a focus due to an increase in the recent observed seismicity there which is most likely linked to anthropogenic activities related to unconventional oil and gas exploration. Seismicity caused by these types of activities is called induced seismicity. The occurrence of moderate to larger induced earthquakes in areas where critical infrastructure is present can be potentially problematic. Here we use a binary forecast method to analyze past seismicity and well production data in order to quantify future areas of increased seismicity. This method splits the given region into spatial cells. The binary forecast method used here has been suggested in the past to retroactively forecast large earthquakes occurring globally in areas called alarm cells. An alarm cell, or alert zone, is a bin in which there is a higher likelihood for earthquakes to occur based on previous data. The first method utilizes the cumulative Benioff strain, based on earthquakes that had occurred in each bin above a given magnitude over a time interval called the training period. The second method utilizes the cumulative well production data within each bin. Earthquakes that occurred within an alert zone in the retrospective forecast period contribute to the hit rate, while alert zones that did not have an earthquake occur within them in the forecast period contribute to the false alarm rate. In the resulting analysis the hit rate and false alarm rate are determined after optimizing and modifying the initial parameters using the receiver operating characteristic diagram. It is found that when modifying the cell size and threshold magnitude parameters within various training periods, hit and false alarm rates are obtained for specific regions in Western Canada using both recent seismicity and cumulative well production data. Certain areas are thus shown to be more prone to potential larger earthquakes based on both datasets. This has implications

Topographic and sedimentary features in the Yap subduction zone and their implications for the Caroline Ridge subduction

Science.gov (United States)

Dong, Dongdong; Zhang, Zhengyi; Bai, Yongliang; Fan, Jianke; Zhang, Guangxu

2018-01-01

The Yap subduction zone in the western Pacific presents some unique features compared to normal intra-oceanic subduction zones such as the subduction of an oceanic plateau. However, due to the relative paucity of geophysical data, the detailed structure remains unknown in this area. In this study, we present the latest high-quality swath bathymetry and multi-channel seismic data acquired synchronously in 2015 across the Yap subduction zone. The topographic and sedimentary features are intensively investigated and a modified evolutionary model of the Yap subduction zone is proposed. The two-stage evolution of the Parece Vela Basin (PVB) produced fabrics that are N-S trending and NW-SE trending. Our seismic data clearly reveal landslide deposits at the upper slope break of the forearc, to the north of the Yap Island, which was identified as the fault notch denoting a lithological boundary in previous work. The swath bathymetry and seismic profile reveal detailed horst and graben structures, including a crescent-shaped fault zone near the contact between the Yap Trench and the Caroline Ridge. A simple geometric model is proposed to explain the structure formation, indicating that the higher topography of the Caroline Ridge resulted in enhanced bending-related extension. A seismic angular unconformity (named R1) is identified in the Sorol Trough, marking the onset of rifting in the trough. Based on the sequence thickness and deposition rate by Deep Sea Drilling Project (DSDP), it is deduced that the Sorol Trough formed at 10 Ma or even earlier. A modified model for the Yap subduction zone evolution is proposed, incorporating three major tectonic events: the proto-Yap Arc rupture in the Oligocene, the collision of the Caroline Ridge and the Yap Trench in the late Oligocene or middle Miocene, and the onset of the Sorol Trough rifting in the late Miocene.

Sedimentary lipid biomarkers in the magnesium rich and highly alkaline Lake Salda (south-western Anatolia

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Jérôme Kaiser

2016-06-01

Full Text Available Lake Salda located in south-western Anatolia is characterized by the presence of living stromatolites and by a low diversity of both phytoplankton and zooplankton due to high pH and magnesium concentration. The most abundant, free sedimentary lipids of the uppermost centimetres of the lake sediments were studied as potential environmental biomarkers, and proxies based on glycerol dialkyl glycerol tetraethers (GDGT were tested in this extreme environment. Dinosterol and tetrahymanol are potentially relevant biomarkers for the dinoflagellate Peridinium cinctum and ciliates, respectively. C20:1 and C25:2 highly branched isoprenoid (HBI alkenes, and n-C17 alkane and n-C17:1 alkene are considered as representing, respectively, diatoms and Cyanobacteria involved in the formation of the stromatolites. Isoprenoid GDGT-0 is assumed to be derived mainly from Euryarchaeota (methanogens, and crenarchaeol from Thaumarchaeota. Allochthonous organic material is represented by long-chain n-alkanes and n-alkanols derived from land plant leaf waxes, as well as branched GDGTs produced by soil bacteria. While pH and temperature proxies based on branched GDGTs are likely not applicable in Lake Salda, TEX86 (tetraether index of tetraethers consisting of 86 carbons, a proxy based on isoprenoid GDGTs, potentially allows estimating mean annual lake surface temperature. Interestingly, C23 and C25 1,2 diols, which have a yet unknown origin, were found for the first time in lake sediments. This study represents the first investigation of sedimentary lipid distribution in an alkaline and magnesium-rich lake in Anatolia, and provides a basis for future biomarker-based paleoenvironmental reconstruction of Lake Salda.

Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history.

Science.gov (United States)

Kim, Jihun; Lim, Dhongil; Jung, Dohyun; Kang, Jeongwon; Jung, Hoisoo; Woo, Hanjun; Jeong, Kapsik; Xu, Zhaokai

2018-03-01

We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10 -5  g/m 2 /yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems. Copyright © 2018 Elsevier Ltd. All rights reserved.