Sample records for matter diagenesis sedimentology

  1. Sedimentology, petrography and early diagenesis of a travertine-colluvium succession from Chusang (southern Tibet)

    Wang, Zhijun; Meyer, Michael C.; Hoffmann, Dirk L.


    The Chusang travertine is situated in southern Tibet at an altitude of ~ 4200 m asl. in a cold-arid, periglacial environment and is characterized by interbedding of hydrothermal carbonate with colluvium. Here we present sedimentological and petrographical data to elucidate the depositional environment and sedimentary processes responsible for hydrothermal carbonate precipitation and early diagenetic alteration as well as clastic sediment accumulation and provide initial 230Th/U ages to constrain the time-depth of this travertine-colluvium succession. Three main travertine lithofacies have been identified: 1) a dense laminated lithofacies, 2) a porous layered lithofacies and 3) an intraclastic lithofacies that results from erosion of pre-existing hot spring carbonate. The colluvium is composed of cohesive debris flow layers that derived from mass-wasting events from the adjacent hillslopes. Micro-fabric analyses suggest that dense laminated travertine forms via rapid calcite precipitation from hot spring water seasonally subjected to severe winter cooling, while porous layered travertine results from seasonal dilution of hot spring water with rain water during the summer monsoon months, which in turn stimulates biological productivity and gives rise to a porous summer layer. Early diagenesis in the form of recrystallization and extensive formation of pore cements is common in the Chusang travertine, but never eradicates the original crystal fabrics completely. The sedimentary architecture of the deposit is conditioned by (i) the gently dipping (~ 10°) pre-existing terrain on which hot spring water is discharged from multiple travertine mounds causing laterally extensive travertine sheets to precipitate, and (ii) the adjacent much steeper (up to 30°) periglacial hillslopes that are the source area of repeated debris flows that accumulate on the travertine surface. The resulting travertine-colluvium succession has a total thickness of ~ 24 m and 230Th/U dating

  2. Sedimentology and diagenesis of windward-facing fore-reef calcarenites, Late Pleistocene of Barbados, West Indies

    Humphrey, J.D.; Kimbell, T.N.


    Late Pleistocene reef terraces in southeastern Barbardos developed extensive fore-reef sand facies during deposition in response to high-energy windward-facing conditions. Sedimentology and diagenesis of these deposits illustrate significant contrasts with previous studies from the leeward west coast. These calcarenites are dominantly skeletal packstones with less common grainstones and wackestones present. The fore-reef sand facies occurs within progradational reef sequences, being conformably overlain by deep-water head coral facies. Medium-bedded, laterally continuous sand sheets retain original depositional slopes, dipping seaward at 10/degrees/-15/degrees/. These fore-reef deposits, in places, are over 30 m thick (average 20 m) and developed rapidly during late Pleistocene glacio-eustatic sea level highstands. Sedimentation rate ranges from 2 to 5 m/1000 years. Areal extent of fore-reef calcarenites in southeastern Barbados is estimated to be 8-10 km/sup 2/. Lithologically, the packstones are composed of an abundance of coralline red algae and the benthic foraminifer Amphistegina sp. Other volumetrically significant allochems include echinoids, mollusks, rhodoliths, peloids, and micritized grains. Micrite in the wackestone and packstone lithologies is likely derived from intense physical/mechanical abrasion of shoal-water reef facies. Diagenesis of these lithologies reflects a complex interplay of meteoric, mixing zone, and marine environments as a result of glacio-eustasy. Differences in diagenetic character are derived from differences in terrace ages, terrace geometry, a paleotopographic control on meteoric ground-water distribution, and high-energy coastal conditions. Diagenetic fabrics include equant, blocky meteoric phreatic calcite; limpid dolomite of mixing zone origin: and peloidal and isopachous fibrous cements from marine precipitation.

  3. Sedimentation, distribution and diagenesis of organic matter in a recent carbonate environment, Abu Dhabi, U. A. E

    Kenig, F.; Huc, A.Y. (Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)); Purser, B.H. (Paris-11 Univ., 91 - Orsay (France). Lab. de Petrologie Sedimentaire et Paleontologie); Oudin, J.-L. (Total CFP, 33 - Pessac (France))


    In the modern hypersaline carbonate lagoon and sabkha sedimentary environments of Abu Dhabi (United Arab Emirates), three types of organic matter originate respectively from microbial mat, Avicennia mangrove, and Halodule lagoonal seagrass. The study of recent sedimentary processes and cross sections through the sabkha sediments leads to the definition of organo-sedimentary facies based on geochemical and sedimentological criteria. This permits the construction of an organo-sedimentary sequence which expresses the Holocene sedimentary record involving a transgressive and a regressive sequence. The various organic facies occur in both sequences. Heterogeneity within the individual organic facies reflects several factors, including sedimentation dynamics, mineral matrix, oxidation and reduction, and selective organic and mineral diagenesis. These parameters are discussed in terms of depositional environment and location within the organo-sedimentary sequence. Changes in distribution, quantity, and preservation potential of the buried organic matter are discussed in terms of sea level changes and sedimentary accretion rates. (10 figures, 32 references) (Author)

  4. Early diagenesis of recently deposited organic matter: A 9-yr time-series study of a flood deposit

    Tesi, T.; Langone, L.; Goñi, M. A.; Wheatcroft, R. A.; Miserocchi, S.; Bertotti, L.


    In Fall 2000, the Po River (Italy) experienced a 100-yr return period flood that resulted in a 1-25 cm-thick deposit in the adjacent prodelta (10-25 m water depth). In the following years, numerous post-depositional perturbations occurred including bioturbation, reworking by waves with heights exceeding 5 m, as well as periods of extremely high and low sediment supply. Cores collected in the central prodelta after the Fall 2000 flood and over the following 9 yr, allowed characterization of the event-strata in their initial state and documentation of their subsequent evolution. Sedimentological characteristics were investigated using X-radiographs and sediment texture analyses, whereas the composition of sedimentary organic matter (OM) was studied via bulk and biomarker analyses, including organic carbon (OC), total nitrogen (TN), carbon stable isotope composition (δ13C), lignin phenols, cutin-products, p-hydroxy benzenes, benzoic acids, dicarboxylic acids, and fatty acids. The 9-yr time-series analysis indicated that roughly the lower half of the original event bed was preserved in the sediment record. Conversely, the upper half of the deposit experienced significant alterations including bioturbation, addition of new material, as well as coarsening. Comparison of the recently deposited material with 9-yr old preserved strata represented a unique natural laboratory to investigate the diagenesis of sedimentary OM in a non-steady system. Bulk data indicated that OC and TN were degraded at similar rates (loss ∼17%) whereas biomarkers exhibited a broad spectrum of reactivities (loss from ∼6% to ∼60%) indicating selective preservation during early diagenesis. Given the relevance of episodic sedimentation in several margins, this study has demonstrated the utility of event-response and time-series sampling of the seabed for understanding the early diagenesis in non-steady conditions.

  5. Bacterial cell wall preservation during organic matter diagenesis in sediments off Peru

    Lomstein, Bente Aagaard; Niggemann, Jutta; Jørgensen, Bo Barker;

    BACTERIAL CELL WALL PRESERVATION DURING ORGANIC MATTER DIAGENESIS IN SEDIMENTS OFF PERU The spatial distribution of total hydrolysable amino acids, total hydrolysable amino sugars and amino acid enantiomers (D- and L-forms) were investigated in surface sediments at 20 stations in the Peru margin: 9...

  6. Microbial Nitrogen Cycling Associated with the Early Diagenesis of Organic Matter in Subseafloor Sediments

    Zhao, R.


    The early diagenesis of organic matter is the major energy source of marine sedimentary biosphere and thus controls its population size; however, the vertical distribution of any functional groups along with the diagenesis of organic matter is remained unclear, especially for those microbes involved in nitrogen transformation which serve as a major control on the nitrogen flux between reservoirs. Here we investigated the vertical distributions of various functional groups in five sediment cores retrieved from Arctic Mid-Ocean Ridge (AMOR), with emphasis on the nitrifiers, denitrifiers and anaerobic ammonium oxidizing bacteria (anammox). We observed the clear geochemical zonation associated with organic matter diagenesis in the sediments based on the pore water profiles of oxygen, nitrate, ammonium, manganese and sulfate, with distinct geochemical transition zones at the boundaries of geochemical zones, including oxic-anoxic transition zone (OATZ) and nitrate-manganese reduction zone (NMTZ). Nitrate was produced in surface oxygenated sediments and nitrate consumption mainly took place at the NMTZ, splitted between re-oxidation of ammonium and manganese (II). Abundances of ammonia oxidizers, nitrite oxidizers, and denitrifiers, estimated through quantitative PCR targeting their respective functional genes, generally decrease with depth, but constantly elevated around the OATZ, NMTZ, and manganese-reduction zone as well. Anammox bacteria were only detected around the NMTZ where both nitrate/nitrite and ammonium are available. These depth profiles of functional groups were also confirmed by the community structure profiling by prokaryotic 16S rRNA gene tag pyrosequencing. Cell-specific rates of nitrification and denitrification, calculated from the bulk net reaction rates divided by functional group abundances, were similar to those values from oligotrophic sediments like North Pond and thus suggested that nitrifiers and denitirifiers populations were in maintenance

  7. Sedimentology, diagenesis, clay mineralogy and sequential analysis model of Upper Paleocene evaporite-carbonate ramp succession from Tamerza area (Gafsa Basin: Southern Tunisia)

    Messadi, Abdel Majid; Mardassi, Besma; Ouali, Jamel Abdennaceur; Touir, Jamel


    Integrated sedimentological studies, diagenesis, sequential analysis and clay mineralogy on the Upper Paleocene rocks in Tamerza area provide important information on the reconstruction of the depositional basin, cyclicity, and paleoclimatic contexts. Facies analysis and petrographic studies have led to the recognition of nine facies that were deposited in three facies belts: Sebkha, inner ramp and outer ramp summarized in a carbonate ramp model: Homoclinal ramp under an arid climate. The upward and lateral changes in thickness and composition show a general regressive trend that records a transition from an outer ramp to Sebkha, creating different types of confinement. The facies stacking patterns constitute several kinds of meter-scale, shallowing-upward cycles. Nine different types of depositional cycles and several models of Sebkha sequences were defined. These different types of facies, characterized within the Thelja Formation, compose seven depositional sequences, mainly made of carbonates, marls and evaporates. Detailed multi approach analysis provides important information on evaporitic sequence stratigraphy. In carbonates beds, the diagenetic analysis provides an overview and chronology of diagenetic processes. A particular attention was paid to early stage cementation which enables us to characterize better the depositional environments. In addition to cementation, other features define the diagenetic history. X-ray diffraction reveals the presence of smectite suggesting an arid climate. Moreover, the clinoptilolite and the frequency of primary dolomite indicate different degrees of confinement. The seven depositional sequences showing a hierarchical organization of many cycles, as described above, suggested that eustatic sea level oscillations caused by cyclic perturbations of the Earth's orbit play a fundamental role in determining the formation of hierarchical cyclic rhythmicity.

  8. Early diagenesis of organic matter in a Sawgrass peat from the Everglades, Florida

    Orem, W.H.; Hatcher, P.G.


    The transformation of plant biopolymers to humic substances in peats during early diagenesis is a critical but poorly understood step in the formation of coal. This paper presents results concerning the structural interrelationships among various fractions of the organic matter in peat and the dissolved organic matter in the pore water from a site in The Everglades, relying primarily on elemental analysis and 13C nuclear magnetic resonance for structural elucidation. Our goal was to obtaine some insight into the sequence of steps involved in the formation of humic substances. Results show that the major change occurring in the whole peat during diagenesis is loss of carbohydrates. The components of the peat which are more resistant to microbial degradation become concentrated in the humin fraction. This resistant fraction of the organic matter includes aliphatic and aromatic components. The aromatic components are thought to be derived from lignin while the aliphatic moieties may represent decomposed algal remains. The carbohydrates lost from the whole peat appear to be concentrated in the fulvic acids and the dissolved organic matter in the pore water. The humic acids consist predominantly of aromatic and aliphatic structures, and may represent partially degraded lignin-like structures and aliphatic compounds from algae. The data presented here suggest that humic and fulvic acids are the partially degraded fractions of the peat while the humin contains the resistant or preserved portion of the organic matter. The proposition that humic substances are formed by the condensation of amino acids and sugars is not supported by the results of this study. ?? 1987.

  9. Biological early diagenesis and insolation-paced paleoproductivity signified in deep core sediment organic matter.

    Chen, Meilian; Kim, Ji-Hoon; Choi, Jiyoung; Lee, Yun Kyung; Hur, Jin


    The dynamics of a large stock of organic matter contained in deep sediments of marginal seas plays pivotal role in global carbon cycle, yet it is poorly constrained. Here, dissolved organic matter (DOM) in sediments was investigated for core sediment up to ~240 meters deep in the East/Japan Sea. The upper downcore profile (≤118 mbsf, or meters below seafloor) at a non-chimney site (U1) featured the exponential production of dissolved organic carbon (DOC) and optically active DOM with time in the pore water above sulfate-methane-transition-zone (SMTZ), concurrent with the increases of nutrients and alkalinity, and the reduction of sulfate. Such depth profiles signify a biological pathway of the DOM production during the early diagenesis of particulate organic matter presumably dominated by sulfate reduction. Below the SMTZ, an insolation-paced oscillation of DOM in a ~405-Kyr cycle of orbital eccentricity was observed at site U1, implying astronomically paced paleoproductivity stimulated by light availability. Furthermore, DOM dynamics of the deep sediments were likely governed by intensive humification as revealed by the less pronounced protein-like fluorescence and the lower H/C and O/C ratios below SMTZ among 15,281 formulas identified. Our findings here provide novel insights into organic matter dynamics in deep sediments.

  10. Sedimentology and geochemistry of carbonates diagenesis. Application to the Malm of the eastern edge of the Paris basin; Sedimentologie et geochimie de la diagenese des carbonates. Application au Malm de la Bordure Est du Bassin de Paris

    Vincent, B


    The important heterogeneity of neritic carbonates reflects: 1 - the facies characteristics of the initial sediments, linked with the diversity of sedimentation environments, and 2 - the post-sedimentation diagenesis characteristics. The aim of this work is to explore this heterogeneity using the {delta}{sup 18}O isotopic signal. A three step pluri-disciplinary approach with different observation scales is established: 1 - a sedimentology study (facies inventory, paleo-environment variations, stratigraphic cycles), 2 - an inventory and chronology of the diagenesis phases and products which have modified he initial sediments, and 3 - a geochemical approach based on the {delta}{sup 18}O signal. This last step combines ionic microprobe measurements performed on separated phases and measurements performed on the whole rock carbonated phase. The carbonate formations under study correspond to the HTM102 borehole made by the ANDRA in the Malm of the eastern edge of the Paris basin. For the stratigraphic approach, some field analogues have been studied (Pagny-sur-Meuse and Gudmont-Villiers sections). (J.S.)

  11. Impact of the simulated diagenesis on sorption of naphthalene and 1-naphthol by soil organic matter and its precursors.

    Guo, Xiaoying; Wang, Xilong; Zhou, Xinzhe; Ding, Xing; Fu, Bin; Tao, Shu; Xing, Baoshan


    Soil organic matter (SOM) in a peat soil, humic acid, and humin and their precursors (i.e., cellulose and lignin) were treated at high temperature (250 and 400 °C) with high pressure in a sealed platinum reaction kittle to simulate the influence of diagenesis on their composition and structure, and impact of the simulated diagenesis on sorption behaviors of hydrophobic organic compounds (HOCs) (i.e., naphthalene and 1-naphthol) by these samples was investigated. High temperature and pressure treatment greatly influenced chemical composition and physical properties of the original samples and their sorption for both naphthalene and 1-naphthol. Sorption of naphthalene by all samples was jointly regulated by hydrophobic and π-π interactions with their alkyl and aromatic carbon moieties, which was derived from the positive correlation between total hydrophobic carbon content of all sorbents and their organic carbon content-normalized sorption coefficients (Koc) for this compound (p = 0.075). However, sorption of 1-naphthol by the tested sorbents was governed by hydrogen bonding with their O-containing polar functionalities, as derived from the positive correlation between Koc values of 1-Naph and their polarity index ((O+N)/C). Difference in sorption mechanisms of naphthalene and 1-naphthol by the original and treated samples noted the great influence of chemical composition of sorbates on their interaction and essential roles of specific interactions (e.g., hydrogen bonding) in sorption of polar compound (i.e., 1-naphthol) to these sorbents. Surface area (SA) and porosity data of sorbents obtained from N2 sorption-desorption isotherms at 77 K showed that new SA and pores were created during the diagenetic process of all original samples, which provided substantial sorption sites and thus enhanced sorption of naphthalene and 1-naphthol. Among all tested samples, physicochemical properties of cellulose were most strongly affected by the simulated diagenetic process

  12. Jellyfish Lake, Palau: early diagenesis of organic matter in sediments of an anoxic marine lake

    Orem, W.H.; Burnett, W.C.; Landing, W.M.; Lyons, W.B.; Showers, W.


    The major postdepositional change in the sedimentary organic matter is carbohydrate biodegradation. Lignin and aliphatic substances are preserved in the sediments. Dissolved organic matter in pore waters is primarily composed of carbohydrates, reflecting the degradation of sedimentary carbohydrates. Rate constants for organic carbon degradation and sulfate reduction in sediments of the lake are about 10?? lower than in other anoxic sediments. This may reflect the vascular plant source and partly degraded nature of the organic matter reaching the sediments of the lake. -from Authors

  13. Sediment Diagenesis and Benthic Flux

    Emerson, S.; Hedges, J.


    Chemical reactions in marine sediments and the resulting fluxes across the sediment-water interface influence the global carbon cycle and the pH of the sea and affect the abundance of CaCO3 and opal-forming plankton in the ocean. On very long timescales these diagenetic reactions control carbon burial in sedimentary rocks and the oxygen content of the atmosphere. Sedimentary deposits that remain after diagenesis are the geochemical artifacts used for interpreting past changes in ocean circulation, biogeochemical cycles, and climate. This chapter is about the processes of diagenesis and burial of the chemical elements that make up the bulk of the particulate matter that reaches the seafloor (organic matter, CaCO3, SiO2, Fe, Mn, and aluminosilicates).Understanding of sediment diagenesis and benthic fluxes has evolved with advances in both experimental methods and modeling. Measurements of chemical concentrations in sediments, their associated pore waters and fluxes at the sediment-water interface have been used to identify the most important reactions. Because transport in pore waters is usually by molecular diffusion, this medium is conducive to interpretation by models of heterogeneous chemical equilibrium and kinetics. Large chemical changes and manageable transport mechanisms have led to elegant models of sediment diagenesis and great advances in understanding of diagenetic processes.We shall see, though, that the environment does not yield totally to simple models of chemical equilibrium and chemical kinetics, and laboratory determined constants often cannot explain the field observations. For example, organic matter degradation rate constants determined from modeling are so variable that there are essentially no constraints on these values from laboratory experiments. In addition, reaction rates of CaCO3 and opal dissolution determined from modeling pore waters usually cannot be reproduced in laboratory experiments of these reactions. The inability to

  14. Authigenic K-NH{sub 4}-feldspar in sandstones: A fingerprint of the diagenesis of organic matter

    Ramseyer, K. [Univ. Bern (Switzerland). Geologisches Inst.; Diamond, L.W. [Univ. Bern (Switzerland). Mineralogisch-Petrographisches Inst.; Boles, J.R. [Univ. of California, Santa Barbara, CA (United States). Dept. of Geological Sciences


    In arkosic sandstones of the San Joaquin and Los Angeles Basins presently at temperatures between 35 C and 174 C, trace amounts of authigenic K-NH{sub 4}-feldspar are present as microfracture fillings and overgrowths on detrital K-feldspar. Microchemical analyses of this authigenic phase reveal up to 80 mole % buddingtonite. The largest ammonium concentrations are observed in a sandy interval of the Antelope shale (80 mole %) and in the Stevens Sands ({approx} 50 mole %) of the San Joaquin Basin. This latter unit was deposited as a turbidite in the organic-rich Fruitvale Shale, an equivalent of the Antelope Shale. The lowest ammonium contents (0-16 mole %) are present in the shallow-marine Vedder Sands and the marginal marine San Joaquin Formation in the same basin. Petrographic, {delta}{sup 18}O, {delta}{sup 13}C, and {sup 87}Sr/{sup 86}Sr analyses of a dolomite cement that postdates authigenic K-NH{sub 4}-feldspar indicate that the feldspar precipitated below 28 C in the zone of methanogenesis, from pore waters with the same Sr signature as sea water at the time of sedimentation. Authigenic K-NH{sub 4}-feldspar is thus an early-diagenetic phase that crystallized prior to oil migration, under anoxic conditions when organic matter releases ammonium. The source of ammonium is bacterial decay of organic matter in the sandstones themselves and/or in contemporaneous shales.

  15. Diagenesis, provenance and depositional environments of the Bunter Sandstone Formation

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    The Bunter Sandstone Formation in the northern North German Basin has large geothermal potential with high porosity and permeability (generally >15% and >100 mD, respectively) and with pore fluid temperatures that are adequate for geothermal energy production (c. 55–60˚C). A combined investigation...... of diagenesis, provenance and depositional environments is used to identify the reservoir rocks that possess the best quality. This is accomplished by integrating various methods including: seismic reflection data, sedimentological description of cores, mineral quantification by point counting, measurement...

  16. Taphonomic and sedimentologic characterization of roof-shale floras

    Gastaldo, R.A.; Pfefferkorn, H.W.; DiMichele, W.A. [Auburn University, Auburn, IL (United States). Dept. of Geology


    Roof-shale floras have been a major source of data for the understanding of Carboniferous vegetation. Early debate on their origin centered around the question of whether these megafloral assemblages are autochthonous or allochthonous. In these discussions, the sedimentological context in which the preserved fossil assemblage (taphoflora) occurred was largely ignored. W.C. Darrah saw the complexity of these issues, presented helpful starting points for further investigations, and influenced the thinking of the next generation. This chapter characterizes the sedimentological and taphonomic features of a spectrum of roof-shale floras. There are three levels at which the preservation of plant parts can be viewed: (1) early taphonomic processes and earliest diagenesis can destroy or preserve plant parts in a given clastic depositional setting; (2) those plant parts that are preserved can be autochthonous, parautochthonour, or allochthonous in relationship to their original place of growth; (3) with respect to a peat layer (coal bed), the overlying clastic material can be deposited in a continuous transition, after a short temporal break (discontinuity), or after a significant hiatus of time. Characterization of roof-shale floras must take into consideration the sedimentological interpretation of the associated lithologies, the stratigraphic sequence, and the taphonomic processes involved in their formation. Characterization is essential before such floras can be used in higher-level interpretations, such as paleoecological reconstructions. 72 refs., 3 figs., 3 tabs.

  17. Recent Trends and Advances in Sedimentology.

    Suttner, Lee J.


    Briefly surveys recent trends and developments in sedimentology. Includes Clastic sedimentary petrology, petrology of argillaceous rocks, terrigenous depositional environments, and chemical sedimentology. (MA)

  18. The evolution of clastic sedimentology

    David Oldroyd


    @@ This valuable book was first published in Japanese in 2002, under the title Sedimentology: a way to the new discipline of earth sciences. Given the problems that nearly all non-Japanese people have in reading Japanese, its translation into English in an expanded form, accomplished with the help of Professor Kenyon-Smith, is exceedingly welcome, given that it is the first book to provide a history of sedimentology.

  19. Sedimentological evolution, diagenesis and hydrocarbon potentiality of late Jurassic carbonates, Eastern Region, Yemen Arab Republic

    El-anbaawy, M.I.H.; Al-thour, K.A. (Dept. of Geology, Faculty of Science, Cairo Univ., Giza (EG))


    On the basis of the lateral and vertical distribution of the lithofacies identified within the Late Jurassic Amran sequence (Thoma Member) in Jabal Al-Balaq area, Marib, Y.A.R., three megafacies were recognized. Proceeding from the shore landwards they are: Ooid bank, including barriers such as reefs and carbonate sand shoals adjacent to the margin of a shallow platform having intertidal to subtidal agitated water, the bank being composed of skeletal packstone, oolitic grainstone and oncolitic packstone; Shelf lagoon, behind the shoal, characterized by less turbulent pelletoidal wackestone, sandy mudstone and algal stromatolite (boundstone); Alluvial coastal plain, including tidal sand flat of the marine shoreline-intertidal area, where cross-bedded sandstone and alluvial fan toe conglomerate were deposited. The apparent small-scale facies variations which are the result of the allocyclic tectonically controlled sea level fluctuations, reflect a complex interfingering of the depositional environments and the resulting rock types. The paragenetic sequence of the post-depositional processes within the siliciclastics inferred is: iron oxide cementation, authigenic growth of mica clays, generation of pressure solution and compaction, and generation of quartz overgrowths. It is indicated that the compaction process followed the neomorphism and cementation within the carbonates.

  20. Sedimentology and paleoenvironments of the Las Chacritas carbonate paleolake, Cañadón Asfalto Formation (Jurassic), Patagonia, Argentina

    Cabaleri, Nora G.; Benavente, Cecilia A.


    The Las Chacritas Member is the lower part of the Cañadón Asfalto Formation (Jurassic). The unit is a completely continental limestone succession with volcanic contributions that were deposited during the development of the Cañadón Asfalto Rift Basin (Chubut province, Patagonia, Argentina). A detailed sedimentological analysis was performed in the Fossati depocenter to determine the paleoenvironments that developed in the context of this rift. The Las Chacritas Member represents a carbonate paleolake system with ramp-shaped margins associated with wetlands that were eventually affected by subaerial exposure and pedogenesis. This process is represented by three main subenvironments: a) a lacustrine setting sensu stricto (lacustrine limestone facies association), represented by Mudstones/Wackestones containing porifera spicules (F1), Intraclastic packstones (F6) and Tabular stromatolites (F10) in which deposition and diagenesis were entirely subaqueous; b) a palustrine setting (palustrine limestone facies association) containing Microbial Mudstones (F2), Intraclastic sandy packstone with ostracode remains (F3), Oncolitic packstone (F5), Brecciated limestone (F7) and Nodular-Mottled limestone (F8) representing shallow marginal areas affected by groundwater fluctuations and minor subaerial exposure; and c) a pedogenic paleoenvironment (pedogenic limestone facies association) including Intraclastic limestone (F4) and Packstones containing Microcodium (F9) facies displaying the major features of subaerial exposure, pedogenic diagenesis and the development of paleosols. The fluvial-palustrine-lacustrine succession shows a general shallow upward trend in which contraction-expansion cycles are represented (delimited by exposure and surface erosion). The variations in the successive formations reflect the responses to fluctuations in a combination of two major controls, the tectonic and local climatic variables. The predominance of the palustrine facies associations was

  1. Sedimentological context of the continental sabkhas of Abu Dhabi

    Lokier, Stephen; Paul, Andreas; Bixiao, Xin


    For more than half a century, the coastal sabkhas of Abu Dhabi have been the focus of intensive research focusing on deposition, early diagenesis and the role of microbial communities. Given all of this activity, it is somewhat surprising that their continental counterparts have been largely neglected with only a brief mention in larger-scale regional studies. This study redresses this imbalance by documenting the sedimentological, mineralogical and early diagenetic characteristics of continental sabkhas that are hosted in the Rub al Khali desert of the United Arab Emirates. During reconnaissance surveys it has been established that organic-rich microbial mats and evaporite minerals, both similar to those observed in the coastal sabkha, also occur in these continental sabkha settings. Satellite imagery was utilised to identify potential field locations for surface and shallow sub surface investigation; subsequent field reconnaissance established the validity of sites in terms of anthropogenic disruption and accessibility. At each site, surface features were described in detail, particularly with reference to any microbial communities or evaporite crusts; sample pits were dug in order to document sub-surface facies geometries and to recover both sediment and pore water samples for subsequent analysis. In each pit, a range of environmental parameters was measured over a prolonged period, including surface and sub-surface temperatures, ground water salinity and dissolved oxygen. Sediment samples were subjected to a range of analyses in order to establish and quantify primary sediment composition and any early diagenetic mineral phases. The results of this study are used to build an atlas of sedimentary structures and textures that are associated with continental sabkha settings. These observations allow us to establish the defining sedimentological and early diagenetic characteristics that can be employed to identify similar depositional environments in ancient

  2. Impact of diagenesis on carbonate mound formation

    van der Land, C.


    This thesis is devoted to define the parameters influencing cold-water coral growth and therefore carbonate mound development with a focus on the impact of diagenesis on mound sediments. The first part of this thesis (Chapters 2 to 4) discusses the distributionand growth history of carbonate mounds,

  3. Pyrite Genesis During Early Diagenesis in Yellow Sea and East China Sea

    段伟民; 陈丽蓉


    The content and isotopic compositions of different sulphur species in pore-water and solid phases have been examined on five sediment cores taken from muddy sediment region in the Yellow Sea and the East China Sea. Relationships among these data have been investigated with the combination of morphology of mineral pyrite and organic matter so as to role out the diagenetic behaviour of sulphur species at the early stage of diagenesis in modern marine sediment and the origin of pyrite formation.

  4. Cyclisation and aromatisation of carotenoids during sediment diagenesis

    Sinninghe Damsté, J.S.; Koster, J.; Baas, M.; Koopmans, M.; Kaam-Peters, H.M.E. van; Geenevasen, J.A.J.; Kruk, C.


    A novel diaryl isoprenoid with an additional aromatic ring, formed from the diaromatic carotenoid isorenieratene by cyclisation and aromatisation during sediment diagenesis, is identified in carbonaceous sedimentary rocks.

  5. 22nd IAS Meeting of Sedimentology

    DavorPavelic; IgorVlahovic; JosipHalamic


    The 22nd IAS Meeting of Sedimentology was held in the Convention Centre of the Grand Hotel Adriatic, in a small touristic town Opatija, located on the eastern Adriatic coast where Central Europe and the Mediterranean meet. It was the second IAS Meeting held in Croatia--the first one, 4th IAS Regional Meeting of Sedimentology, was held in Split in 1983. The Meeting in Opatija was organized by the Institute of Geology (Zagreb) and the Croatian Geological Society. The sponsor was Ministry of Science and Technology of the Reoublic of Croatia.

  6. Source characterisation of Sedimentary organic matter in mangrove ecosystems of northern Kerala, India: Inferences from bulk characterisation and hydrocarbon biomarkers

    Resmi, P.; Manju, M.N.; Gireeshkumar, T.R.; RatheeshKumar, C.S.; Chandramohanakumar, N.

    diagenesis of sedimentary organic matter. The elemental and isotopic ratios along with sedimentary chlorophyll a content, suggested substantial contribution of planktonic organic matter apart from mangrove/terrestrial derived organic matter. The sources...

  7. Early diagenesis and recrystallization of bone

    Keenan, Sarah W.; Engel, Annette Summers


    One of the most challenging problems in paleobiology is determining how bone transforms from a living tissue into a fossil. The geologic record is replete with vertebrate fossils preserved from a range of depositional environments, including wetland systems. However, thermodynamic models suggest that bone (modeled as hydroxylapatite) is generally unstable in a range of varying geochemical conditions and should readily dissolve if it does not alter to a more thermodynamically stable phase, such as a fluorine-enriched apatite. Here, we assess diagenesis of alligator bone from fleshed, articulated skeletons buried in wetland soils and from de-fleshed bones in experimental mesocosms with and without microbial colonization. When microbial colonization of bone was inhibited, bioapatite recrystallization to a more stable apatite phase occurred after one month of burial. Ca-Fe-phosphate phases in bone developed after several months to years due to ion substitutions from the protonation of the hydroxyl ion. These rapid changes demonstrate a continuum of structural and bonding transformations to bone that have not been observed previously. When bones were directly in contact with sediment and microbial cells, rapid bioerosion and compositional alteration occurred after one week, but slowed after one month because biofilms reduced exposed surfaces and subsequent bioapatite lattice substitutions. Microbial contributions are likely essential in forming stable apatite phases during early diagenesis and for enabling bone preservation and fossilization.

  8. Influence of macrobenthos on chemical diagenesis of marine sediments

    Aller, R.C.


    Diagenetic reactions involving the decomposition of organic matter and the dissolution, mobilization, and reprecipitation of metals sensitive to oxidation-reduction reactions, are most intense and rapid in the upper 1 m and especially the upper 10 cm of marine sediment. It is in this upper zone where most benthic organisms live and interact with sediments and where exchange rates of dissolved and particulate material between sediment and overlying water are largely determined. In Long Island Sound, U.S.A., both spatial and temporal trends in sediment chemistry and the flux of material out of the bottom demonstrate the control of diagenesis by bottom fauna. /sup 234/Th//sup 238/U disequilibrium studies demonstrate that particle reworking rates near the sediment-water interface vary both temporally and spatially in the Sound. The most rapid reworking occurs in protobranch-inhabited bottom areas as do the highest /sup 234/Th inventories. Excess /sup 234/Th profiles in the sediment allow determination of the rates of selected diagenetic reactions, such as Mn/sup + +/ production, near the sediment surface. Both the /sup 234/Th disequilibrium and flux measurements indicate that intra-estuarine redistribution of metals continually takes place.

  9. Evolution of pore space in sandstones in relation to diagenesis

    Zhu, G.


    Results are described from studying the collector properties of a bed of sandstones of Yan-10 at the oil field Malin of the Ordosskiy oil and gas basin. The bed is represented by ancient river sandstones of the Jurassic age occurring on eroded surface of the Triassic deposits (Yangan series) and covered with bed of coal deposits Yan-9. The following conclusions were drawn from the results of the studies. Evolution of the pore space actually is the process of gradual substitution of the primary pores by secondary; in this case decrease in porosity in the quartz sandstones occurs mainly because of depositing in the pores of authigenic minerals, and in the sandstones whose grains consist of minerals with lower mechanical strength, because of packing. Secondary porosity develops because of dissolving and kaolinization in the sandstones with high content of feldspars. This process is possibly associated with decarboxilation of organic matter of interlayers of coal and calcareous shales under the influence of increased temperature in the submersion process. Since it has been established that considerable influence on porosity comes from the mineralogical position of the sandstones controlled by the sources of formation, in order to reveal the zones for development of primary and secondary porosity, it is very important to reveal the sources of removal of detrital rocks. A study was also made of the influence of diagenesis on uniformity and texture of the sandstones (by the methods of curves of capillary pressure).

  10. Fractal and its application to sedimentology

    余继峰; 李增学; 韩美莲


    In the paper,the foundation,development,basic conception and general characteristics of fractal and the calculating method of the fractional dimension are expounded briefly, and the current situation and prospect of the fractal application in sedimentology are discussed stressly. Both sedimentary process and sedimentary record behave the fractal feature of the self-similarity structure. External form and internal texture of the sediments and the distribution of the grain-size of the sediments are of fractal feature very well, and the size of the fractional dimension is the quantitative index of the complexity of the background when they are formed. The further analysis on the multi-fractal feature of the sedimentary body is the base of the fractal simulation and forecast, and it is the key of the application of the fractal theory to sedimentology.

  11. Paleomagnetic dating of burial diagenesis in Mississippian carbonates, Utah

    Blumstein, Angela M.; Elmore, R. Douglas; Engel, Michael H.; Elliot, Crawford; Basu, Ankan


    The objective of this study is to test models for the origin of widespread secondary magnetizations in the Mississippian Deseret Limestone. The Delle Phosphatic Member of the Deseret Limestone is a source rock for hydrocarbons, and modeling studies indicate that it entered the oil window in the Early Cretaceous during the Sevier orogeny. Paleomagnetic and rock magnetic results from the Deseret Limestone and the stratigraphically equivalent Chainman Shale in central and western Utah indicate that the units contain two ancient magnetizations residing in magnetite. Burial temperatures are too low for the magnetizations to be thermoviscous in origin, and they are interpreted to be chemical remanent magnetizations (CRMs). Fold tests from western Utah indicate the presence of a prefolding Triassic to Jurassic CRM. Geochemical (87Sr/86Sr, δ13C, and δ18O) and petrographic analyses suggest that externally derived fluids did not alter these rocks. This CRM was acquired at the beginning of the oil window and is interpreted to be the result of burial diagenesis of organic matter. A second younger CRM in western central Utah is apparently postfolding and is probably Late Cretaceous to early Tertiary in age. On the basis of the thermal modeling, the timing overlaps with the oil window. These results are consistent with a connection between organic matter maturation and remagnetization. Modeling of the smectite-to-illite transformation in the Deseret Limestone suggests a mean age prior to acquisition of both CRMs, although the range for illitization overlaps with the Triassic to Jurassic CRM. The results of this study support the hypothesis that pervasive CRMs can be related to burial diagenetic processes. In addition, paleomagnetism can be used to determine the timing of such processes, which can benefit hydrocarbon exploration efforts.

  12. Trace Metals And Organic Matter Diagenesis At The Oman Margin

    Alagarsamy, R.

    Trace Metals (e.g. Mn and Fe) play an important role as secondary oxidants in the degradation of sedimentary OM under sub-oxic conditions. Hence the remineralisation of organic constituents of sediments in the marine environment may significantly...

  13. Effect of diagenesis on compaction of reservoir rocks

    Olgaard, D.; Cameron, S.; Dunsmuir, J.; Herhold, A.; King, H; Gooch, M. J.


    Predicting sediment porosity-depth trends and ultimately the quality of reservoir rocks requires an understanding of mechanical and chemical compaction mechanisms during diagenesis. In many siliciclastic sediments porosity versus depth profiles can be predicted from the sediment’s stress history. In carbonates such predictions are more difficult because chemical diagenesis is prevalent even within a few meters of the seafloor. We used a systematic laboratory approach to investigate th...

  14. Sedimentology, paleoclimatology, and diagenesis of Post-Hercynian continental deposits in the South-Central Pyrenees, Spain

    Nagtegaal, Peter J.C.


    The first chapter of the post-Hercynian geologic history of the South-Central Pyrenees is recorded in a sequence of fluvial and volcanic deposits which reach a total of added maximum thicknesses of more than 2300 m and date from the Westphalian D up to and including the Lower Triassic. The present s

  15. Diagenesis and porosity reduction in the Late Cretaceous Wyandot Formation, offshore Nova Scotia : a comparison with Norwegian North Sea chalks

    Ings, S.J.; MacRae, R.A.; Pe-Piper, G. [Saint Mary' s Univ., Halifax, NS (Canada). Dept. of Geology; Shimeld, J.W. [Natural Resources Canada, Dartmouth, NS (Canada). Geological Survey of Canada, Bedford Inst. of Oceanography


    Chalk is an attractive reservoir target for hydrocarbon exploration because even deep sea-buried chalk has the ability to preserve porosities of up to 40 per cent. The preservation of primary porosity is related to diagenesis, resedimentation, over-pressuring and hydrocarbon saturation. In the past 3 decades, large oil and gas discoveries have been made in chalk units in the North Sea, Texas, Colorado and the offshore Scotian Shelf in eastern Canada. Chalks of the Upper Cretaceous Wyandot Formation on the Scotian Shelf have preserved porosities up to 30 per cent and are the reservoir for a small gas and oil discovery in the Primrose N-50 exploration well. The Wyandot Formation extends about 500 km along the length of the margin and consists mostly of limestone with major chalk intervals. It is largely understudied, despite its potential as a hydrocarbon reservoir or seal. In this study, conventional core samples of Wyandot Formation chalk recovered from both the Primrose A-41 and Eagle D-21 wells were analyzed. The depositional history, diagenesis and porosity-reducing mechanisms within the Formation were clarified through scanning electron microscopy, oxygen and carbon isotope analysis, wireline logs and porosity data. The porosity history of North Sea chalks was then compared with that of the Wyandot Formation. It was determined that the Wyandot chalks are in situ pelagic deposits, compared to the allochthonous North Sea chalks. The dominant mechanisms of porosity reduction in the Wyandot chalks are mechanical compaction and dissolution. It is possible that North Sea type allochthonous reservoirs exist in distal locations on the Scotian Slope because large volumes of Wyandot chalk have been eroded on part of the Scotian Shelf. Therefore, further exploration is warranted to provide a better understanding of the sedimentology and porosity distribution of the in situ Wyandot Formation. 20 refs., 2 tabs., 11 figs.

  16. Experimental observations on fungal diagenesis of carbonate substrates

    Kolo, Kamal; Keppens, Eddy; PréAt, Alain; Claeys, Philippe


    Carbonate substrates (dolomites and limestones) are susceptible to fungal attack that results in significant microbial diagenesis of these substrates. In a 15-day experimental study, fungi growing in Petri dishes from airborne spores attacked petrographic thin sections and chips prepared from the dolomites of Terwagne Formation (Viséan, Bocahut quarry at Avesnes-sur-Helpe, northern France) and limestones of the Morrone di Pacentro Formation (Lower Cretaceous, Italy). The analyses of the fungal material (samples of mycelia), thin sections and chips under optical microscopy, scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Raman spectroscopy and stable isotopes (C and O) revealed an extensive fungally induced diagenesis. The results indicate strong diagenesis and biomineral neomorphism: neo-dolomite, glushinskite, weddellite, whewellite and possibly struvite, as well as intense substrate "de-micritization" and "micritization" with oxalates, grain bridging and cementation, open space filling, formation of intergranular and intragranular porosity, and permeability enhancement. Advanced stages of diagenesis were characterized by dissolution and replacement of original minerals by new substrates produced by fungal biomineralization. The formation of new substrates on the original attacked surfaces produced microscale stratification. Stable isotope analysis of fungal biomineralized material and of attacked and unattacked chip surfaces revealed marked differences in their isotopic signatures. The C and O isotopes of biomineralized material within the fungal mass were fractionated differently as compared to the signature measured in the original and unattacked surfaces. In sedimentary cycles, such microbially modified isotopic signature of carbonate substrates may be used to define microbial events, and consequently whether certain types of diagenesis were produced by microbial interaction. The finding of neo-dolomite formed

  17. Quantification of diagenesis in Cenozoic sharks: Elemental and mineralogical changes

    Labs-Hochstein, Joann; MacFadden, Bruce J.


    Diagenesis of bone during fossilization is pervasive, however, the extent of this process varies with depositional environment. This study quantifies diagenesis of shark vertebral centra through analysis of a suite of physical and chemical characters including crystallinty index (CI), carbonate content, and elemental concentrations. Although shark skeletons are initially cartilaginous, the soft cartilage of the vertebral centra is replaced with carbonate hydroxyapatite during growth. Nine vertebral centra are analyzed from lamnoid (Lamnoidea) sharks ranging in age from the cretaceous to recent using Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma mass spectrometry (ICPMS). The variables CI, carbonate content, rare earth element (REE) concentrations, Ca/P, Ba/Ca, Sr/Ba, (La/Yb) N, (La/Y) N, (La/Yb) N vs. (La/Sm) N, La/Yb, and Ce anomalies elucidate the diagenetic and depositional environments of the seven fossil vertebral centra. The two extant centra demonstrate the initial, unaltered end-member conditions for these variables. Two fossil vertebral centra ( Carcharodon megalodon and Isurus hastalis) demonstrate a strong terrestrial influence during diagenesis (distinctive flattening of shale-normalized REE patterns) that masked the seawater signal. Three centra ( Carcharodon auriculatus, Carcharodon angustidens, and Creotxyrhina mantelli) have indications of some terrestrial influx evident by some flattening of the REE patterns relative to seawater. The terrestrial influence in these five shark centra ( C. megalodon, I. hastalis, C. auriculatus, C. angustidens and C. mantelli) are interpreted to represent a primarily nearshore habitat for these species. In contrast, the two Otodus obliquus centra have REE patterns that represent the original seawater signal and have no indications of terrigenous input. These results indicate that fossil shark vertebral centra have the potential to understand diagenesis and reconstruct

  18. Meteoric diagenesis, marine diagenesis, and microporosity in Pleistocene and Oligocene limestones, Enewetak Atoll, Marshall Islands

    Saller, Arthur H.; Moore, Clyde H.


    Microporosity occurs in Pleistocene and Oligocene limestones cored on Enewetak Atoll. In cores of Pleistocene limestone (10-80 m deep), mi microporosity is present in aragonitic skeletal grains that underwent partial intrafabric dissolution (chalkification) leaving a porous meshwork of aragonite needles. Microporous aragonite is most abundant in 5-10 m thick intervals below zones of intense diagenesis associated with paleo-freshwater lenses. Extensive microporosity was apparently generated by slow intrafabric dissolution of aragonite in mixing zones below freshwater lenses. Microporous aragonite is an intermediate step in the calcitization or dissolution of aragonite. Most calcitized aragonite (neomorphic calcite) formed by precipitation of sparry calcite in (over) microporous aragonite. Aragonitic fossils were not converted to microporous, microcrystalline calcite. Therefore, data from the Pleistocene of Enewetak suggest that widespread, microporous, microcrystalline calcite does not form directly from pure aragonite, at least not in open meteoric systems or mixing zones. Microporous micrite occurs in Oligocene wackestones 930 m deep deposited in a slope environment. The microporous micrite is characterized by equant and prismatic crystals of low-magnesium calcite (LMC). Equant crystals are anhedral to euhedral and 2-10 μm in diameter. Prismatic calcite crystals are subhedral, 5-10 μm wide, and 20-50 μm long. Stable isotopic and trace element geochemistry suggest that microporous micrite formed by diagenetic alteration of high-magnesium calcite (HMC) micrite in deep seawater undersaturated with respect to HMC but supersaturated with respect to LMC (probably near the sediment-water interface). Mineralogy and crystal morphology of the microporous aragonite is very different from microporous shelf limestones in the Thamama Group (Cretaceous, Persian Gulf; see Moshier, 1989). Equant microcrystals of calcite in the Oligocene micrites are similar to those in

  19. The mathematics of early diagenesis: From worms to waves

    Boudreau, Bernard P.


    The changes that sediments undergo after deposition are collectively known as diagenesis. Diagenesis is not widely recognized as a source for mathematical ideas; however, the myriad processes responsible for these changes lead to a wide variety of mathematical models. In fact, most of the classical models and methods of applied mathematics emerge naturally from quantification of diagenesis. For example, small-scale sediment mixing by bottom-dwelling animals can be described by the diffusion equation; the dissolution of biogenic opal in sediments leads to sets of coupled, nonlinear, ordinary differential equations; and modeling organisms that eat at depth in the sediment and defecate at the surface suggests the one-dimensional wave equation, while the effect of waves on pore waters is governed by the two- or three-dimensional wave equation. Diagenetic modeling, however, is not restricted to classical methods. Diagenetic problems of concern to modern mathematics exist in abundance; these include free-boundary problems that predict the depth of biological mixing or the penetration of O2 into sediments, algebraic-differential equations that result from the fast-reversible reactions that regulate pH in pore waters, inverse calculations of input functions (histories), and the determination of the optimum choice in a hierarchy of possible diagenetic models. This review highlights and explores these topics with the hope of encouraging further modeling and analysis of diagenetic phenomena.

  20. Spatial and Seasonal Studies of Sedimentological and Neoichnological Characteristics from Mangrove areas of Karachi, Pakistan

    Noor Us Saher


    Full Text Available The purpose of this study is to appraise the physicochemical properties of mangrove sediments and their influence on neoichnological properties produced by different crab species from Korangi Creek (S1 and Sandspit backwater areas (S2 and S3, Karachi. The significant spatial, seasonal and tidal differences (p <0.05 were examined in %moisture, %porosity and sorting coefficient Φ.The significant spatial and seasonal variations were observed in total organic matter, mean Φ, skewness Φ and kurtosis Φ of sediment. Neoichnological properties (burrow number, diameter and total burrow opening area were observed with significant differences among the macrohabitat (stations and microhabitat (tidal levels. The correlation analysis indicated that the neoichnological properties are strongly linked with sedimentological properties such as water contents, total organic matter and textural parameters. This study could be employed to distinguish between different paleoenvironmental controlling factors, predicated on similar paleoichnological features made by similar fossil organisms in a mangrove environment.

  1. The end-Permian regression in the western Tethys: sedimentological and geochemical evidence from offshore the Persian Gulf, Iran

    Tavakoli, Vahid; Naderi-Khujin, Mehrangiz; Seyedmehdi, Zahra


    Detailed sedimentological and geochemical records across the Permian-Triassic boundary (PTB) in five offshore wells of the central Persian Gulf served to interpret the end-Permian sea-level change in this region. A decrease in sea level at the PTB was established by petrographical and geochemical study of the boundary. Thin sections showed that Upper Permian strata are composed of dolomite with minor anhydrite, changing into limestone in Lower Triassic sediments. Brine dilution toward the boundary supports sea-level fall in the Permian-Triassic transition, reflected by a decrease in anhydrite content and a shallowing-upward trend from lagoonal to peritidal facies. Isotopic changes at the boundary are in favor of sea-level fall. Changes in both carbon (from about 4 to -1‰) and oxygen (from 2 to -5‰) stable isotopes show negative excursions. The shift in carbon isotope values is a global phenomenon and is interpreted as resulting from carbonate sediment interaction with 12C-rich waters at the end-Permian sea-level fall. However, the oxygen isotope shift is attributed to the effect of meteoric waters with negative oxygen isotope values. The increase in strontium isotope ratios is also consistent with the high rate of terrestrial input at the boundary. The effect of meteoric conditions during diagenesis is evident from vuggy and moldic porosities below the PTB. The following transgression at the base of the Triassic is evident from the presence of reworked fossils and intraclasts resulting from deposition from agitated water.

  2. Hétérogenéité quantitative et qualitative de la matière organique dans les argiles du Kimmeridgien du val de Pickering (Yorkshire, UK. Cadre sédimentologique et stratigraphique Quantitative and Qualitative Heterogeneity of the Organic Matter Within the Kimmeridge Clay of the Vale of Pickering (Yorkshire, Uk. Sedimentological and Stratigraphical Framework

    Penn I. E.


    character of the sequence is geographically and stratigraphically homogeneous, indicating generally unchanging conditions of deposition overall. Sedimentation generally occurred in a low energy depositional environment and comprises essential clay minerals (kaolinite, illite and mixed-layer illite-smectite with accessory biogenic calcite, mainly planktonic (coccolith material. Intercalated with the main body of mudstone, are beds of carbonate, which facilitate inter borehole correlation. These beds are coccolith-rich limestones which have subsequently been dolomitised, increasingly so toward the west, by a process dependent on the amount of organic carbon present. Their great lateral extent witnesses to geodynamic controlof regional extent. Preserved organic carbon content shows a gradual increase (by over 50% when traced from the highin the east towards the centre of the basin in the west, where the beds are thickest. This is true despite cyclic fluctuation in both quantity and quality which can also be followed from the Reighton 87 to the Marton 87 borehole. In each borehole, stratigraphical variability of organic carbon is related to, fundamentally cyclic, sedimentological variation. The earliest preserved organic matter lies within the Cymodoce Zone. Three subsequent maxima were attained; at the top of the Eudoxus Zones, the base of the Hudlestoni Zone, and at the base of the Pectinatus Zone. The two highest horizons correspond to episodes of maximum transgression or highstand. Although very variable in time and space, the geographical distribution of organic matter may be easily explained, being related to bed thickness, depth of water and transgressive and regressive cycles of sedimentation. Consistent variations which has been found on the scale of tens of kilometres in the Cleveland Basin can be moreover extended at a palaeogegraphical scale. For example, the phase of maximum occurrence of organic material at the top of the Wheatleyensis Zone corresponds to the

  3. Reconstructing the Holocene depositional environments along the northern coast of Sfax (Tunisia): Mineralogical and sedimentological approaches

    Lamourou, Ali; Touir, Jamel; Fagel, Nathalie


    A sedimentological and mineralogical study of sedimentary cores allowed reconstructing the evolution of depositional environments along the Northern coast of Sfax (Tunisia). The aim of this research work is to identify the factors controlling the sedimentation from the Holocene to the Present time. Three 30-m sediment cores collected by drilling at 30 m water depth were analyzed for their color, magnetic susceptibility signal, grain size by laser diffraction, organic matter content by loss of ignition, carbonate content by calcimetry and mineralogy by X-ray diffraction on bulk powder and clay <2 μm. They broadly present the same sedimentological and mineralogical features. Microscopical observations of petrographic slides allowed identifying six main sedimentary facies. Bulk mineralogical assemblages comprised clay minerals, quartz, calcite, gypsum and K-feldspars were examined. Considerable change was observed in the carbonate content that mimicked the bioclaste abundance and diluted the detrital minerals (clay minerals, quartz and feldspars). The gypsum mainly occurred in the lower sedimentary columns (SC12 and SC9) and in the upper/middle of core SC6. The clay fraction was made of a mixture of kaolinite, illite, smectite and palygorskite with no clear variation through core depth. Both grain-size parameters and magnetic susceptibility profile showed a sharp transition in the upper 2-5 m of the sedimentological columns. Coarse, sandy to gravely sediments characterized by a low magnetic susceptibility signal were replaced by fine bioclastic-rich clayey sediments. The analysis of vertical succession of depositional facies revealed a fluvial depositional environment (coastal plain) basically marked by fluvial channels and inundation plains at the bottom of all cores. However, core-top sediments recorded a littoral marine environment with sand depositions rich in gastropods, lamellibranches and algæ. Depositional facies, sedimentological and mineralogical

  4. Early diagenesis of amino acids in NE Atlantic continental margin sediments

    Grutters, M.C.H.


    This thesis concentrates on early diagenesis of amino acids in sediments across the NE Atlantic continental slope. Early diagenesis comprises the degradation and transformation processes that take place during transport of amino acids through the water column and the early stages of burial in the

  5. Geothermal alteration of clay minerals and shales: diagenesis

    Weaver, C.E.


    The objective of this report is to perform a critical review of the data on the mineral and chemical alterations that occur during diagenesis and low-grade metamorphism of shale and other clay-rich rocks - conditions similar to those expected from emplacement of heat-producing radioactive waste in a geologic repository. The conclusions drawn in this document are that the following type of alterations could occur: smectite alteration, ion mobilization, illitic shales, kaolinite reactions, chlorite reactions, organic reactions, paleotemperatures, low temperature shales, high temperature shales, and phase equilibrium changes.

  6. Impact of stylolitization on diagenesis of a Lower Cretaceous carbonate reservoir from a giant oilfield, Abu Dhabi, United Arab Emirates

    Paganoni, Matteo; Al Harthi, Amena; Morad, Daniel; Morad, Sadoon; Ceriani, Andrea; Mansurbeg, Howri; Al Suwaidi, Aisha; Al-Aasm, Ihsan S.; Ehrenberg, Stephen N.; Sirat, Manhal


    Bed-parallel stylolites are a widespread diagenetic feature in Lower Cretaceous limestone reservoirs, Abu Dhabi, United Arab Emirates (UAE). Diagenetic calcite, dolomite, kaolin and small amounts of pyrite, fluorite, anhydrite and sphalerite occur along and in the vicinity of the stylolites. Petrographic observations, negative δ18OVPDB, fluid inclusion microthermometry, and enrichment in 87Sr suggest that these cements have precipitated from hot basinal brines, which migrated along the stylolites and genetically related microfractures (tension gashes). Fluid migration was presumably related to lateral tectonic compression events related to the foreland basin formation. The low solubility of Al3 + in formation waters suggests that kaolin precipitation was linked to derivation of organic acids during organic matter maturation, probably in siliciclastic source rocks. The mass released from stylolitization was presumably re-precipitated as macro- and microcrystalline calcite cement in the host limestones. The flanks of the oilfield (water zone) display more frequent presence and higher amplitude of stylolites, lower porosity and permeability, higher homogenization temperatures and more radiogenic composition of carbonates compared to the crest (oil zone). This indicates that oil emplacement retards diagenesis. This study demonstrates that stylolitization plays a crucial role in fluid flow and diagenesis of carbonate reservoirs during basin evolution.

  7. Reading and Abstracting Journal Articles in Sedimentology and Stratigraphy.

    Conrad, Susan Howes


    An assignment centered on reading journal articles and writing abstracts is an effective way to improve student reading and writing skills in sedimentology and stratigraphy laboratories. Each student reads two articles and writes informative abstracts from the author's point of view. (PR)

  8. Impact of Diagenesis on Biosignature Preservation Potential in Playa Lake Evaporites in Verde Formation, Arizona: Implications for Mars Exploration

    Shkolyar, S.; Farmer, J. D.


    Major priorities for Mars science include assessing the preservation potential and impact of diagenesis on biosignature preservation in aqueous sedimentary environments. We address these priorities with field and lab studies of playa evaporites of the Verde Formation (upper Pliocene) in Arizona. Evaporites studied include bottom-nucleated halite and displacive growth gypsum in magnesite-rich mudstone. These lithotypes are potential analogs for ancient lacustrine habitable environments on Mars. This study aimed to understand organic matter preservation potential under different diagenetic histories. Methods combined outcrop-scale field observations and lab analyses, including: (1) thin-section petrography to understand diagenetic processes and paragenesis; (2) X-ray powder diffraction to obtain bulk mineralogy; (3) Raman spectroscopy to identify and place phases (and kerogenous fossil remains) within a microtextural context; (4) Total Organic Carbon (TOC) analyses to estimate weight percentages of preserved organic carbon for each subfacies endmember; and (5) electron microprobe to create 2D kerogen maps semi-quantifying kerogen preservation in each subfacies. Results revealed complex diagenetic histories for each evaporite subfacies and pathways for organic matter preservation. Secondary gypsum grew displacively within primary playa lake mudstones during early diagenesis. Mudstones then experienced cementation by Mg-carbonates. Displacive-growth gypsum was sometimes dissolved, forming crystal molds. These molds were later either infilled by secondary sulfates or recrystallized to gypsum pseudomorphs with minor phases present (i.e., glauberite). These observations helped define taphonomic models for organic matter preservation in each subfacies. This work has the potential to inform in situ target identification, sampling strategies, and data interpretations for future Mars Sample Return missions (e.g., sample caching strategies for NASA's Mars 2020 mission).

  9. Sedimentological correlation of heterogeneous reservoir rocks: effects of lithology, differential compaction and diagenetic processes

    Hammer, Erik


    Correlation of reservoir rocks is a challenge in many types of reservoirs around the world today. In a time where the focus has slowly shifted away from the giant fields, towards development of smaller, more marginal fields, the importance of addressing these challenges is increasing. The purpose of the thesis is to investigate the effects of lithology, diagenesis and differential compaction on correlation of reservoir architecture in a fluviodeltaic reservoir. To be able to address these issues several types of data, including seismic, core sections and petrophysical wireline logs, have been subjected to measurements, calculations and interpretations to be able to construct a sedimentological and sequence stratigraphic framework based on a reservoir reconstruction work flow. First, the regional and local (field wide) geological evolution for the Aare Formation in the Heidrun Field, offshore Mid-Norway, is elucidated, including evolution of the palaeodepositional environment and the prevailing depositional controlling factors. These studies included a facies description of studied wells based on core and wireline log data, and description/ interpretation of the reservoir sequence stratigraphy. From these studies eight facies associations have been identified and described, indicating a fluvial-deltaic depositional environment. A sequence stratigraphic model based on these facies associations is suggested for the studied well data and includes five candidate sequence boundaries and eight flooding surfaces, including a marine flooding surface. Four of these surfaces are interpreted as allogeneic, suggesting regional base level change, whereas the remaining nine surfaces are suggested as resulting from local, autogenic factors. Next, the compact ability of the identified facies associations was quantified in a diagenesis study using optical microscopy, SEM micro-probe measurements and XRD analyses. The para genetic sequence proposed suggests that abundant early

  10. Recording of climate and diagenesis through sedimentary DNA and fossil pigments at Laguna Potrok Aike, Argentina

    Vuillemin, Aurèle; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda; The Pasado Science Team


    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. In theory, benthic microbial community composition should depend on environmental features and geochemical conditions of surrounding sediments, as well as ontogeny of the subsurface environment as sediment degraded. In principle, DNA in sediments should be composed of ancient and extant microbial elements persisting at different degrees of preservation, although to date few studies have quantified the relative influence of each factor in regulating final composition of total sedimentary DNA assemblage. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two climatic intervals (Mid-Holocene, 5 ka BP; Last Glacial Maximum, 25 ka BP) whose sediments harbored active microbial populations were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. The genetic assemblage recovered from the Holocene record revealed a microbial community displaying metabolic complementarities that allowed prolonged degradation of organic matter to methane. The series of Archaea identified throughout the Holocene record indicated an age-related stratification of these populations brought on by environmental selection during early diagenesis. These characteristics were associated with sediments resulting from endorheic lake conditions and stable pelagic regime, high evaporative stress and concomitant high algal productivity. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. Comparison of sedimentary DNA composition

  11. Chemical and Mechanical processes during burial diagenesis of chalk

    Borre, Mai Kirstine; Lind, Ida


    or larger influence on the textural development. In the chalk interval below, compaction is not the only porosity reducing agent but it has a larger influence on texture than concurrent recrystallization. Below 850 m grain-bridging cementation becomes important resulting in a lithified limestone below 1100......Burial diagenesis of chalk is a combination of mechanical compaction and chemical recrystallization as well as cementation. We have predicted the characteristic trends in specific surface resulting from these processes. The specific surface is normally measured by nitrogen adsorption but is here...... in the Pacific, where a > 1 km thick package of chalk facies sediments accumulated from the Cretaceous to the present. In the upper 200-300 m the sediment is unconsolidated carbonate ooze, throughout this depth interval compaction is the principal porosity reducing agent, but recrystallization has an equal...

  12. Modelling approaches in sedimentology: Introduction to the thematic issue

    Joseph, Philippe; Teles, Vanessa; Weill, Pierre


    As an introduction to this thematic issue on "Modelling approaches in sedimentology", this paper gives an overview of the workshop held in Paris on 7 November 2013 during the 14th Congress of the French Association of Sedimentologists. A synthesis of the workshop in terms of concepts, spatial and temporal scales, constraining data, and scientific challenges is first presented, then a discussion on the possibility of coupling different models, the industrial needs, and the new potential domains of research is exposed.

  13. Geochemistry and Sedimentology of Jhill Limestone of Gaj Formation,in Cape Monze and Adjoining Area,Karachi



    Among several lithostratigraphic subdivisions of the Gaj Formation of Miocene age,the Jhill limestone is entirely different with respect to its colour,texture and structures.This limestone unit has been evaluated to elaborate its geochemical and sedimentological characteristics.The distribution of various elements in the acid-soluble fraction has been studied in order to determine their mineralogy,sedimentary environment,facies and diagenesis.Mineralogy,recrystallization and other diagenetic changes are the main factors affecting the distribution of trace elements and their mutual relationships in the limestones.Samples of the Jhill limestone show depletion in large-sized ions(Sr,Pb & K)and also in the ions that are not compatible with calcite space group.Elements(Fe,Mn,Zn,Cu & Co) having distribution coefficient(D)above unity for natural calcites,are more enriched.Microscopic and X-ray studies revealed nearly complete conversion of aragonite into stable low-Mg calcite. An attempt has also been made to verify the reefal conditions for theese limestones on the basis of geochemical studies.The plots of Sr and oter facies-indicator elements show that the majorits of the beds belong to forereef flank facies with some algal baks.Low Mg/Ca and Sr/Ca ratios suggest that a phreatic diagenetic environment prevailed after the deposition.High concentrations of Cr,Ni,and Co in the Jhill limestone show a positive correlation with a higher amount of insoluble residue,which reflects a relatively high rate of influx of terrigenous material.

  14. Diagenesis of conifer needles in a coastal marine environment

    Hedges, John I.; Weliky, K.


    Physically intact fir, hemlock and cedar needles were isolated from different horizons of a sediment core from a coastal marine bay (Dabob Bay, Washington State, U.S.A.) and from nearby trees and forest litter. Green fir, hemlock and cedar needles were all characterized by glucose-rich aldose mixtures (~30% of tissue carbon), the production of vanillyl and cinnamyl CuO-derived phenols (~8% of tissue carbon) and the presence of both pinitol and myo-inositol (1-2% of tissue carbon). Needles from forest litter were enriched in lignin phenols and non-glucose aldoses and depleted in glucose and cyclitols. The sediment core contained an average of 10 mg/1 of physically intact fir, hemlock and cedar needles, which occurred in similar relative abundances and accounted for less than 1% of the total nonwoody gymnosperm tissue. Compared to the green and litter counterparts, all sedimentary needles were greatly depleted in cyclitols, glucose and p-coumaric acid and enriched in vanillyl phenol precursors. The degree of elevation of vanillyl phenol yield from the degraded needles was used to estimate minimal carbon losses from the samples, which ranged from near 40% for needle litter to almost 70% for the deepest (~100 years old) sedimentary fir/hemlock samples. Although downcore increases in carbon loss and refractory organic components indicated in situ diagenesis, the bulk of overall degradation occurred either on land or during the first 10-20 years after deposition. Atomic C/N ratios of degraded needles were lower than for green counterparts, but nitrogen was lost overall. These relative changes indicate the following stability series: vanillyl phenols > N > ferulic acid, p-hydroxy phenols, most aldoses and bulk tissue > glucose and p-coumaric acid > cyclitols (near 100% loss). Vanillic acid to vanillin ratios, (Ad/Al)v, of the green fir and hemlock needles were unusually high (0.36-0.38) and decreased downcore. Diagenesis also decreased the cinnamyl/vanillyl phenol ratio

  15. Micro-morphological and molecular approaches of early diagenesis of organic matter in a cyperaceous peat in tropical environment (Tritrivakely, Madagascar). Paleo-environmental implications; Approches micromorphologiques et moleculaire de la diagenese precoce de la matiere organique dans une tourbe a cyperacees en milieu tropical (Tritrivakely, Madagascar). Implications paleoenvironnementales

    Bourdon, S.


    The first meter of the peat material sampled at the Tritrivakely swamp (high plateaus of Madagascar) has been studied in order to determine the nature, sources and degradation ways of the organic matter (OM) accumulated during the last 2300 years. In surface peat, the OM coming from vascular plants undergoes a strong mineralization of its main components. Morphologically, this early degradation leads to a transformation into amorphous OM flakes in huge quantity all along the profile. At the TEM scale, the amorphous OM is made of: bio-resistant lipo-polysaccharide laminar structures inherited from the epiderm tissues of the plants, fibrillary polysaccharide structures coming from the degradation of vegetal walls, and phenolic amorphous matter probably poly-condensed. The peat texture observed with a cryo-SEM presents a tridimensional organic network, probably polysaccharide, which makes the material frame. Two ratios (xylose + arabinose/glucide and cinnamic units/lignin) deduced from the analysis of glucide and lignin have been determined as markers of cyperaceaes. The evolution of these parameters along the profile shows that these plants have dominated the site during the accumulation era of the peat. The marker of the degrading bacteria of these plants is the ratio (rhamnose + mannose + fucose + non-cellulosic glucose)/glucide. This ratio is correlated with the acids/aldehydes ratio of the syringic and vanillic units of lignin, thus reflecting a bacterial degradation of hemi-celluloses. The marker of algae, in particular diatoms, seems to be the galactose/glucide ratio. The evolution of these bio-markers along the peat section, in relation with the evolution of global geochemical and petrographic parameters, has permitted to identify a change in the environmental conditions at about 1500 B.P. (J.S.)

  16. Bacterial mediation, red matrices diagenesis, Devonian, Montagne Noire (southern France)

    Préat, Alain; Mamet, Bernard; Bernard, Alain; Gillan, David


    Two Devonian red carbonate rock sections are studied in the Montagne Noire, at Coumiac (Frasnian/Famennian) and at the Pic de Vissou (Eifelian/Givetian). The sediments are grey-red mudstones and wackestones rich in pelagic fossils. They are characteristic of an outer ramp. The Coumiac sequence is condensed with numerous hardgrounds and hiatuses. The Pic de Vissou succession is more complete and of shallower origin. In both cases, the origin of the red coloration of the micritic matrix is probably linked to bacterial activity which produced submicronic hematite. Both iron and manganese concentrations are low (average 0.2%). Bacteria form ferruginous microstromatolites, blisters, microtufts, `hedgehogs' filling sponge perforations and thin continuous mineralized films (probably biofilms). Hardgrounds are underlined by ferruginous microstromatolites. The origin of the matrix color is probably related to the destruction of these bacterial constructions, the submicronic hematite ultimately coating the crystal faces of the calcite mosaic. During early lithification, microfissures appeared and were invaded by microbial colonies. Scanning electron microscopy (SEM) shows that these colonies are composed of spheroidal beads. This suggests continuity of the bacterial activity during early diagenesis. Later on, these early fissures were cut by burrows. Subsequently a secondary fissure network transected all the previously mentioned sedimentary structures. This late fissure network is characterized by diagenetically remobilized hematite and/or calcite. The latest alterations are stylolites and ultimate tectonic fractures.

  17. Kinetic Modeling of Diagenesis of Eogene Lacustrine Sandstone Reservoirs in the Jianghan Basin, Southeastern China

    倪师军; 卿海若; 唐建武; 周美夫; 李泽琴


    In the Tuoshi oilfield, located in the Cenozoic Jianghan Basin of southeastern China, there have been found hydrocarbon reservoirs hosted in lacustrine sandstones of the Eogene Xingouzui Formation. The main diagenetic features identified in these sandstones include the dissolution of detrital K-feldspar and albite grains, the precipitation of quartz as overgrowths and/or cements, and the precipitation and/or transformation of clay minerals. These diagenetic features were interpreted to have occurred in early, intermediate and late stages, based on the burial depth. The kinetics of fluid-mineral reactions and the concentrations of aqueous species at each stage of diagenesis were simulated numerically for these lacustrine sandstones, using a quasi-stationary state approximation that incorporates simultaneous chemical reactions in a time-space continuum. During the early diagenetic stage, pore fluid was weakly acidic, which resulted in dissolution of K-feldspar and albite and, therefore, led to the release of K + , Na + , Al3 + and SiO2(aq) into the diagenetic fluid. The increased K+ , Na + , Al3+ and SiO2(aq) concentrations in the diagenetic fluid caused the precipitation of quartz, kaolinite and illite. At the beginning of the intermediate diagenetic stage the concentration of H + was built up due to the decomposition of organic matter, which was responsible for further dissolution of K-feldspar and albite and precipitation of quartz, kaolinite, and illite. During the late diagenetic stage, the pore fluid was weakly alkaline, K-feldspar became stable and was precipitated with quartz and clay minerals.When the burial depth was greater than 3000 m, the pore fluids became supersaturated with respect to albite, but undersaturated with respect to quartz, resulting in the precipitation of albite and the dissolution of quartz. The diagenetic reactions forecasted in the numerical modeling closely matched the diagenetic features identified by petrographic examination, and

  18. Lithostratigraphic description, sedimentological characteristics and depositional environments of rocks penetrated by Illela borehole, Sokoto Basin, NW Nigeria: A connection between Gulf of Guinea Basins

    Toyin, A.; Adekeye, O. A.; Bale, R. B.; Sanni, Z. J.; Jimoh, O. A.


    The basal unit of the succession in the Illela borehole belongs to the Dange Formation comprising thick calcareous and variably coloured dark-greyish shale of 36.30 m thick which is overlain by a 31.44 m thick limestone of Kalambaina Formation with 1.7 m thick shaly-limestone inclusive. The uppermost part of the section belongs to the Gwandu Formation which has intercalation of silty-clay, muddy siltstones with well lithified ironstone capping the borehole section. The limestone/carbonate microfacie as deduced from their salient lithologic, sedimentologic and paleontologic features are comparable to standard microfacie (SMF) types 9 and 10, i.e. bioclastic wackestone/bioclastic micrite and packstone-wackestone respectively. Diagenetically, syndepositional and early diagenesis have taken place particularly cementation and replacement in the carbonate rocks and these have greatly affected the reservoir potential negatively. The matrix/grain relationships indicate a shallow marine environment of deposition. The borehole section is delineated into upper foraminifera and lower ostracod biostratigraphic units as no formal biostratigraphic zonation could be attempted due to low diversity of both benthic foraminifera, marine ostracods and the absence of planktonic foraminifera. The similarity of the ostracod assemblages between this study area, Illela borehole, West Africa, North Africa (Libya), Mali and Niger Republic) and South-Western Nigeria (West Africa) suggests that a marine connection exists between the Gulf of Guinea and the Sokoto Basin via the area occupied by the River Niger during the Paleocene.

  19. Sedimentological evidence for debris-flow formation of Martian gullies

    de Haas, Tjalling; Hauber, Ernst; Ventra, Dario; Conway, Susan; Kleinhans, Maarten


    Gullies are among the youngest landforms formed by liquid water on Mars, and therefore of critical importance in resolving the planet's recent hydrologic and climatic history. The key to estimating the amount of liquid water involved in gully formation is their formative mechanism. Water-free sediment flows, debris flows and fluvial flows, which all require very different amounts of liquid water, contributed to gully formation but their abundance and effectiveness differs greatly between sites. We show that many gullies dominantly formed by debris flows, based on sedimentological analysis of outcrops in gully-fans rather than surficial debris-flow features, which are often degraded beyond recognition by weathering and wind erosion or masked by ice-dust mantling. This resolves the controversy between previously published morphometric analyses implying debris-flow formation and observations of modified fan surfaces often interpreted to have formed by fluvial flows. Furthermore, it shows that deriving formative processes on gullies from surface characteristics can be highly misleading, which should therefore be inferred from multiple approaches, including sedimentological outcrop and morphometric analyses.

  20. Tracking the Evolution of FE-,TI-OXIDE Phase Changes in Microbial Fossilization Experiments: Understanding the Role of Microbes in Diagenesis

    Bower, D. M.; Steele, A.


    The complex relationships between microbes and minerals under different chemical and geologic conditions over time is still not well constrained. In many ancient sedimentary rocks on Earth, “fossil” microstructures often contain interesting mineral assemblages that are dominated by clays and metal oxides. In some cases, microfossils are preserved along with Fe and Ti-oxides that contain trace amounts of graphitic carbon. Complicated histories and atmospheric inputs have influenced much of the mineralic makeup of the subaerially exposed rocks we see today, and these assemblages may not the same as what was originally formed with the rocks billions of years ago. To elucidate changes in Fe- and Ti-oxides during diagenesis, precipitates of iron and titanium oxides produced by microbes were compared to those formed abiotically. The samples were tracked over time to monitor the phase changes in minerals along with changes in the state of organic matter. This was carried out under laboratory controlled conditions of increasing temperatures and pressures to mimic the effects of diagenesis and low-grade metamorphism. A suite of analytical techniques were used to identify the mineral phases and carbonaceous compounds in these samples, including micro Raman spectroscopy, SEM, and XRD. To compliment this technique, NanoSims measurements of C, O, Fe, and Ti isotopes will also be made on samples analyzed by TEM. Collectively, the results show a correlation between the phase changes of Fe- and Ti-oxide and the presence of microbes under diagenetic conditions. The preliminary results presented here are part of an ongoing study and can be applied to understanding the role of microbes in diagenesis. It is hoped that we may also establish mineralic biosignatures, and in the process continue to perfect instrumental techniques that can be used on future planetary exploration missions.

  1. "Cryptic" diagenesis and its implications for speleothem geochronologies

    Bajo, Petra; Hellstrom, John; Frisia, Silvia; Drysdale, Russell; Black, Jay; Woodhead, Jon; Borsato, Andrea; Zanchetta, Giovanni; Wallace, Malcolm W.; Regattieri, Eleonora; Haese, Ralf


    Speleothems are usually considered as one of the most amenable palaeoclimate archives for U-series dating. A number of studies in recent years, however, report cases of diagenetic alteration which compromises the use of U-series systematics in speleothems, resulting in inaccurate U-Th ages. Here we present the results of a high-resolution U-Th dating study of a stalagmite (CC26) from Corchia Cave in Italy where we document a number of departures from an otherwise well-defined age-depth model, and explore potential causes for these outliers. Unlike examples illustrated in previous studies, CC26 contains no visible evidence of neomorphism, and appears, at least superficially, ideally suited to dating. Good reproducibility obtained between multi-aliquot U-Th analyses removes any possibility of analytical issues contributing to these outliers. Furthermore, replicate analyses of samples from the same stratigraphic layer yielded ages in stratigraphic sequence, implying very localized open-system behavior. Uranium loss is suggested as a causative mechanism on account of the fact that all the outliers are older than their assumed true age. A limited number of micro-voids were observed under micro-CT analyses, and it is proposed that these were pathways for U loss. Uranium-loss modelling allows us to constrain the possible timing of diagenetic alteration and indicates that the precursor for the outlier with the largest age discrepancy (309%) must have been aragonite. This study indicates that visibly unaltered speleothems may still contain small domains that have experienced post-depositional alteration. Such "cryptic" diagenesis, as recorded in this stalagmite, has implications for the constancy of accuracy of the U-series dating technique, and suggests a need for careful examination of speleothems prior to dating, particularly in low-resolution U-Th studies.

  2. Remagnetization and Clay diagenesis in Jurassic Sediments of Skye, Scotland

    Basu, A.; Elliott, W.; Wampler, J.; Elmore, R.; Engel, M. H.


    The thrust of this study is to test the hypothesized connection between magnetite authigenesis and diagenetic reactions forming illite, an idea based on the results of paleomagnetic, rock magnetic, geochemical, and petrographic/SEM studies on Jurassic sedimentary rocks of Skye, Scotland. The Jurassic rocks in southern Skye contain a dual polarity magnetization residing in magnetite that is interpreted as a chemical remanent magnetization (CRM) and has directions similar to those of early Tertiary igneous rocks on Skye. The presence-absence test and the timing of acquisition for this CRM suggest that magnetite authigenesis is related to the smectite-to-illite conversion, and that clay diagenesis is a viable remagnetization mechanism. The clay fractions consist of illite-smectite (I-S), kaolinite, and trace amounts of chlorite. The I-S exhibits Kalkberg order (IISI) and typically contains ˜ 85% to 90% illite layers based on the positions of the 001 reflection. The 2M1, 1M and 1Md illite polytypes are present in variable proportions depending on size fraction. The K-Ar dates of I-S in the finest fraction range from 100 to 131 Ma while the K-Ar dates of I-S of the coarse fractions range from 160-210 Ma. In all cases, the dates of the finest I-S are much greater than the Tertiary CRM ages recorded in these rocks (65 Ma). The K-Ar dates decrease with decrease in particle size. At first approximation, the decrease is thought to reflect smaller amounts of detrital illite in the finer fractions. The youngest K-Ar dates of I-S are significantly greater than the CRM age recorded in these sediments. The most likely explanation of the discordance between K-Ar dates and CRM is that the finest fractions contain small amounts of detrital illite.

  3. Study of Diagenesis and Pore Evolution of Triassic Jialingjiang Formation in Southern Puguang Gasfield

    Qi Chen


    Full Text Available The second member of Jialingjiang formation is considered to be an important gas reservoir with good exploration prospects in the southern Puguang gasfield. The diagenesis types are analyzed and different diagenetic stages are divided by analyzing carbon and oxygen isotopes as well as observing the slices. The widespread forms of diagenesis in the research area principally include compaction, cementation, pressure solution, dolomitization, recrystallization, dissolution, and tectonic disruption, among which cementation, dissolution, dolomitization, and recrystallization contribute greatly to the development of porosity in the reservoir. The reservoir has experienced four diagenetic stages: syndiagenetic stage, early stage of diagenesis, diagenetic stage, and late diagenetic stage. Most of the primary pores were destroyed in the diagenetic evolution stages of reservoir; the present porosity mainly belongs to the secondary pores.

  4. Diagenesis of Paleogene sandstone from Kong 1 Member of Southern Kongdian in Huanghua depression


    Huanghua depression is one of the richest areas in petroleum and natural gas in China. The Paleogene mainly consists of sandstone with facies of river, delta, fan delta and littoral-shallow lacustrine. Diagenesis played an important role in the properties of reservoir rocks. Applying X-ray diffraction, on the basis of analyzing many cores and thin sections, the authors studied diagenesis of Paleogene sandstone reservoir rocks in kongl Menber of southern Kongdian in Huanghua depression. Diagenetic complexity shows that the sandstone in this area underwent compaction, cementation, isolation, recrystallization during the burying of sediments, and the first three compose the major diagenesis. The compaction and cementation led to decreasing porosity, and the solution of unsteady minerals also results in increasing in porosity.

  5. Sedimentological control on Mn, and other trace elements, in groundwater of the Bengal delta.

    McArthur, J M; Sikdar, P K; Nath, B; Grassineau, N; Marshall, J D; Banerjee, D M


    To reveal what controls the concentration and distribution of possibly hazardous (Mn, U, Se, Cd, Bi, Pb) and nonhazardous (Fe, V, Mo, PO(4)) trace elements in groundwater of the Bengal delta, we mapped their concentrations in shallow groundwater (sedimentology and sources of water. Areas of less negative δ(18)O reveal recharge by sources of evaporated water. Concentrations of Fe, As, Mo, and PO(4) are high in palaeo-channel groundwaters and low in palaeo-interfluvial groundwaters. Concentrations of U, V, and Mn, are low in palaeo-channel groundwaters and high in palaeo-interfluvial groundwaters. Concentrations of Fe and Mn are highest (18 and 6 mg/L respectively) at dual reduction-fronts that form strip interfaces at depth around the edges of palaeo-interfluvial aquifers. The fronts form as focused recharge carries dissolved organic carbon into the aquifer margins, which comprise brown, iron-oxide bearing, sand. At the Mn-reduction front, concentrations of V and Mo reach peak concentrations of 3 μg/L. At the Fe-reduction front, concentrations of PO(4) and As reach concentrations 3 mg/L and 150 μg/L respectively. Many groundwaters contain >10 mg/L of Cl, showing that they are contaminated by Cl of anthropogenic origin and that organic matter from in situ sanitation may contribute to driving reduction.

  6. Genesis Types and Diagenesis Compaction Mechanisms of Sandstone Rreservoirs in Dynamic Environments in Oil/Gas Basins in China

    Shou Jianfeng; Si Chunsong; Wang Xin


    The diversity of sandstone diagenesis mechanisms caused by the complex geological conditions of oil/gas basins in China could hardly be reasonably explained by the traditional concept of burial diagenesis. Three genesis types of thermal diagenesis, tectonic diagenesis and fluid diagenesis are presented on the basis of the dynamic environment of the oil/gas basins and the controlling factors and mechanisms of sandstone diagenesis. Thermal diagenesis of sandstone reservoirs is related not only to the effect of formation temperature on diagenesis, but also to the significant changes in diagenesis caused by geothermal gradients. The concept of thermal compaction is presented. Thermal compaction becomes weaker with increasing depth and becomes stronger at a higher geothermal gradient. At the same formation temperature, the sandstone porosity in the region with a lower geothermal gradient is e0.077+0.0042T times higher than that in the region with a higher geothermal gradient. Both sudden and gradual changes are observed in diagenetic evolution caused by structural deformation. Average sandstone compaction increased by 0.1051% for every 1.0MPa increase of lateral tectonic compressional stress, while late tectonic napping helped to preserve a higher porosity of underlying sandstone reservoir. Fluid diagenesis is a general phenomenon. The compaction caused by fluid properties is significant. The coarser the grain size, the stronger the fluid effect on compaction. The greater the burial depth, the weaker the fluid effect on compaction for the specific reservoir lithology and the greater the difference in the fluid effects on compaction between different grain sizes.

  7. Sedimentology, hydrogeology and hydrogeochemistry of Machile Basin, Zambia

    Banda, Kawawa Eddy

    An important environmental problem in arid to semi-arid regions of the world is salinisation of water resources. Moreover, most of these regions are inhabited by poor communities in developing countries, with limited or no financial resources to develop suitable alternatives to meet their basic...... water needs. With increasing world population and increasing effects of climate change, groundwater resources are seen as a suitable alternative. However, the exploitation of groundwater in these regions requires knowledge of aquifer structure and genesis, and mechanisms that control hydrochemistry....... Water resources practioners in arid and semi-arid regions accept that future development of groundwater resources depends largely on the degree and rate of salinisation. This PhD study focuses on investigating the sedimentological and hydro-geochemical conditions that have shaped the groundwater...


    Yudhicara Yudhicara


    Full Text Available Post tsunami survey of the October 25, 2010, Mentawai tsunami, has been carried out by a collaboration team of Indonesian-German scientists from 20 to 28 November 2010. One activity of the researches were investigation on tsunami deposits along the coast following the event that devastated the islands of Sipora, North Pagai and South Pagai. Sedimentological properties of Mentawai tsunami deposit were explained by this study, from both megascopic and laboratory result. In general, beaches along the study area are underlying by a stretch of reef limestone, sediments mostly composed of white sand while grey sand was found only at Malakopa. Tsunami sediments were taken from 20 locations, start from Betumonga at Sipora Island until Sibaru-baru Island at the southern tip of the study area. The thickness of tsunami deposits are ranged between 1.5 and 22 cm, which are generally composed of fine to coarse sand in irregular boundaries with the underlying soil. Based on grain size analysis, variation of sedimentological properties of tsunami deposits range between phi=-0,5793 and phi=3,3180 or very coarse to very fine sand. Tsunami deposits mostly have multiple layers which described their transport processes, run up at the bottom and back wash at the top. Structural sediments such as graded bedding of fining upward, parallel lamination and soil clast were found. The grain size distribution curves show two types of mode peak, unimodal and multimodal which are indication of different sorting condition representing the source materials. While segment grain size accumulative plot generally shows domination of dilatation and traction transport mechanism rather than suspension. In general, very rare fossils were found from Mentawai tsunami deposit, but those findings gave information on how depth tsunami start to scour the seafloor and transport it landward, such as an abundance of Sponge spicule was found which indicate shallow water environments (20-100 m

  9. Relationship between radionuclides and sedimentological variables in the South Atlantic Continental Margin; Relacoes entre radionuclideos e variaveis sedimentologicas na Margem Continental do Atlantico Sul

    Ferreira, Paulo A.L.; Figueira, Rubens C.L., E-mail:, E-mail: [Universidade de Sao Paulo (IO/USP), SP (Brazil). Instituto Oceanografico


    There is a lack of information regarding marine radioactivity in sediments of the Continental Margin of the South Atlantic. {sup 137}Cs and {sup 40}K radioactivity and sedimentological variables were determined in superficial sediment samples. It was demonstrated that {sup 40}K is a good indicator for sediment granulometry, whilst {sup 137}Cs presents a good correlation with its chemical composition. Moreover, it was identified through the radiometric data the occurrence of input of allochtonous matter to the Brazilian southernmost compartment from the Rio de La Plata estuary, as previously reported in the literature. (author)

  10. Dynamics of Late Quaternary sapropel periods documented by micropaleontological and sedimentological data from North Aegean Sea

    Gkaniatsa, Georgia; Kontakiotis, George; Antonarakou, Assimina; Drinia, Hara; Anastasakis, George


    Located at the interface of the mid/high latitude climate system and affected by the North Atlantic Oscillation and the monsoonal system over Africa, the Mediterranean Sea has a unique potential to record the occurrence and phasing of climatic changes in both systems. In particular, the eastern Mediterranean Sea is more sensitive and faster responding to external forcing than the open ocean due to smaller size and partial isolation. A manifestation of the high sensitivity of the eastern Mediterranean sedimentary environment to climatic forcing is the periodic deposition of dark colored and organic matter rich sediments, termed "sapropels". In particular their formation is closely correlated with the reduction in ventilation, due to low salinity surface water layer, leading to anoxia at the bottom and preservation of organic matter, and/or the increase in primary productivity in the photic zone. To address which factor is more responsible for the sapropel's formation, a high-resolution study of planktonic foraminiferal abundances in two cores from North Aegean was carried out. Their response reflects the essential information about the paleoceanographic evolution in the water column in terms of stratification and productivity during the different sapropel events covering the last 90 kyrs. Cores M 22-67 and M22-68 were recovered from the water depths of 175 and 305 m respectively in the Chios Basin (North Aegean Sea). Both cores approximately span the last 90 ka, exposing the most recent S1 and the older S3 sapropels. They particularly exposed at very high resolution compared to most occurrences throughout the eastern Mediterranean, because of the highest sediment accumulation rates occurred in the study basin. Application of this information to the study hemipelagic sediment cores, through the planktonic foraminiferal analyses, suggests that we further contribute to existing evidence of climatic instability during sapropel deposition in eastern Mediterranean Sea

  11. [Degradation of biomolecules: a comparative study of diagenesis of DNA and proteins in human bone tissue].

    Harbeck, Michaela; Ritz-Timme, Stefanie; Schröder, Inge; Oehmichen, Manfred; von Wurmb-Schwark, Nicole


    Diagenesis of macromolecules is a not yet fully understood process that can be important for anthropological and forensic research. Trying to elucidate the diagenesis of DNA and proteins we investigated the process of fragmentation of DNA and razemisation of aspartic acid in human bone material. We created an in vitro-model of accelerated aging by incubating bone samples in hot water. A comparison of diagenesis of molecules in those artificially aged samples with altogether 30 historical bones from different regions and of different ages was carried out. The in vitro-model showed the expected positive correlation between the increase of razemisation of aspartic acid and DNA fragmentation, while there was a much lesser correlation when investigating historical bones. The in vitro-model showed the expected correlation between the increase of razemisation of aspartic acid and DNA fragmentation and to a much lesser extent in historical bones. This study shows that diagenesis is probably influenced by additional forces affecting different macromolecules in different ways.

  12. Excretion is Faster Than Diagenesis for Nutrient Recycling in Lake Michigan Benthos

    Aguilar, C.; Cuhel, R. L.


    Regeneration of phytoplankton growth nutrients including ammonium (NH4+) and phosphate (HPO4=) occurs in aquatic systems worldwide through biogeochemical processes of diagenesis. Organic matter falling to the bottom accumulates in sediments, and bacterial decomposition removes oxygen from the sub-surface. Anaerobic metabolism is energetically inefficient, and bacteria a few cm below the surface respire or ferment organic matter into carbon dioxide or organic acids, excreting nitrogen (NH4+) or phosphorus inorganic 'waste'. Subsurface production of bacterial metabolic products often leads to sharp gradients in porewater concentrations of NH4+ and HPO4=, which drive diffusive flux out of the sediments into overlying water. Aquatic systems with totally aerobic water overlying anoxic sediment (e.g., Lake Michigan) have muted efflux of certain inorganic nutrients arising from organic matter decomposition. For example, NH4+ is oxidized to nitrate in the upper few mm of surficial sediments by nitrifying bacteria. Strong subsurface porewater gradients, especially of redox- or geochemically-reactive compounds, often decline to low values well below the sediment-water interface, indicating transformation by sediment bacterial populations, or by purely geochemical processes such as calcium hydroxyphosphate (apatite) precipitation. For these, little flux to the water column occurs. In Lake Michigan, neither NH4+ nor HPO4= escapes substantially from the biogeochemical barriers between their diagenetic sources and overlying waters, either before or after ecosystem alteration by invasive quagga mussels (QM). Silicate and total CO2 evade unimpeded in the same cores. The organic matter deposited from the water column is also the nutrition of benthic bivalve filter feeders such as QM in Lake Michigan, or the Asian Clam in San Francisco Bay. In animal metabolism for energy production, only the carbon component is oxidized through respiration, with NH4+ (from protein) and HPO4= (from

  13. Subtle trap recognition based on seismic sedimentology-A case study from Shengli Oilfield

    Huang Handong; Zhang Ruwei; Luo Qun; Zhao Di; Peng Yongmin


    Seismic sedimentology is the study of sedimentary rocks and facies using seismic data. However, often the sedimentary body features can't be described quantitatively due to the limit of seismic resolution. High resolution inversion offsets this limitation and is applied to seismic sedimentology to identify subtle traps under complex geologic conditions, thereby widening the applicable range of seismic sedimentology. In this paper, based on seismic sedimentology, seismic phase-controlled nonlinear random inversion is used to predict the sandy conglomerate reservoir of Es3 in the Chezhen depression in Shengli Oilfield. Thickness and sedimentary microfacies maps of sandy conglomerate bodies in several stages are presented and several subtle traps were predicted and verified by drilling.

  14. MOSAIC: An organic geochemical and sedimentological database for marine surface sediments

    Tavagna, Maria Luisa; Usman, Muhammed; De Avelar, Silvania; Eglinton, Timothy


    Modern ocean sediments serve as the interface between the biosphere and the geosphere, play a key role in biogeochemical cycles and provide a window on how contemporary processes are written into the sedimentary record. Research over past decades has resulted in a wealth of information on the content and composition of organic matter in marine sediments, with ever-more sophisticated techniques continuing to yield information of greater detail and as an accelerating pace. However, there has been no attempt to synthesize this wealth of information. We are establishing a new database that incorporates information relevant to local, regional and global-scale assessment of the content, source and fate of organic materials accumulating in contemporary marine sediments. In the MOSAIC (Modern Ocean Sediment Archive and Inventory of Carbon) database, particular emphasis is placed on molecular and isotopic information, coupled with relevant contextual information (e.g., sedimentological properties) relevant to elucidating factors that influence the efficiency and nature of organic matter burial. The main features of MOSAIC include: (i) Emphasis on continental margin sediments as major loci of carbon burial, and as the interface between terrestrial and oceanic realms; (ii) Bulk to molecular-level organic geochemical properties and parameters, including concentration and isotopic compositions; (iii) Inclusion of extensive contextual data regarding the depositional setting, in particular with respect to sedimentological and redox characteristics. The ultimate goal is to create an open-access instrument, available on the web, to be utilized for research and education by the international community who can both contribute to, and interrogate the database. The submission will be accomplished by means of a pre-configured table available on the MOSAIC webpage. The information on the filled tables will be checked and eventually imported, via the Structural Query Language (SQL), into

  15. Asian monsoon modulation of nonsteady state diagenesis in hemipelagic marine sediments offshore of Japan

    Chang, Liao; Bolton, Clara T.; Dekkers, Mark J.; Hayashida, Akira; Heslop, David; Krijgsman, Wout; Kodama, Kazuto; Paterson, Greig A.; Roberts, Andrew P.; Rohling, Eelco J.; Yamamoto, Yuhji; Zhao, Xiang


    We have identified millennial-scale variations in magnetic mineral diagenesis from Pacific Ocean sediments offshore of Japan that we correlate with changes in organic carbon burial that were likely driven by Asian monsoon fluctuations. The correlation was determined by identifying offsets between the positions of fossil diagenetic fronts and climatically induced variations in organic carbon burial inferred from magnetic and geochemical analyses. Episodes of intense monsoon activity and attendant sediment magnetic mineral diagenesis also appear to correlate with Heinrich events, which supports the existence of climatic telecommunications between Asia and the North Atlantic region. Several lines of evidence support our conclusions: (1) fluctuations in down-core magnetic properties and diagenetic pyrite precipitation are approximately coeval; (2) localized stratigraphic intervals with relatively stronger magnetic mineral dissolution are linked to enhanced sedimentary organic carbon contents that gave rise to nonsteady state diagenesis; (3) down-core variations in elemental S content provide a proxy for nonsteady state diagenesis that correlate with key records of Asian monsoon variations; and (4) relict titanomagnetite that is preserved as inclusions within silicate particles, rather than secondary authigenic phases (e.g., greigite), dominates the strongly diagenetically altered sediment intervals and are protected against sulfidic dissolution. We suggest that such millennial-scale environmental modulation of nonsteady state diagenesis (that creates a temporal diagenetic filter and relict magnetic mineral signatures) is likely to be common in organic-rich hemipelagic sedimentary settings with rapidly varying depositional conditions. Our work also demonstrates the usefulness of magnetic mineral inclusions for recording important environmental magnetic signals.

  16. Recording of climate and diagenesis through fossil pigments and sedimentary DNA at Laguna Potrok Aike, Argentina

    Vuillemin, A.; Ariztegui, D.; Leavitt, P. R.; Bunting, L.; Pasado Science Team


    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. Although marine sedimentary microbial assemblages are often defined by their surrounding geochemical conditions, the influence of environmental features upon microbial development and post-depositional survival remains largely unknown in the lacustrine realm. Due to long-term microbial activity, the composition of environmental DNA can be expected to evolve with sediment depth and over time and therefore should reflect both ancient and extant microbial populations, but this hypothesis has rarely been tested using a multiproxy approach. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two well defined climatic intervals whose sediments harboured active microbial populations and measurable ATP were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. Bacterial and archaeal 16S rRNA gene sequences recovered from the Holocene record revealed a microbial community adapted to subsaline conditions actively producing methane during organic matter degradation. These characteristics were associated with sediments resulting from endorheic lake conditions with high evaporative stress and concomitant high algal productivity. Moreover, archaeal clone libraries established throughout the Holocene record indicate an age-related stratification of these populations, consistent with a gradual use of organic substrates after deposition. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. These patterns

  17. On metal diagenesis in contaminated sediments of the Deule river (northern France)

    Lesven, L. [Universite Lille 1 (USTL), FRE CNRS 3298 Geosystemes, Equipe de Chimie Analytique et Marine, 59655 Villeneuve d' Ascq cedex (France); Lourino-Cabana, B. [Universite Lille 1 (USTL), FRE CNRS 3298 Geosystemes, Equipe de Chimie Analytique et Marine, 59655 Villeneuve d' Ascq cedex (France)] [Faculty of Natural Sciences and Technology, Department of Chemistry, 7491 Trondheim (Norway); Billon, G.; Recourt, P. [Universite Lille 1 (USTL), FRE CNRS 3298 Geosystemes, Equipe de Chimie Analytique et Marine, 59655 Villeneuve d' Ascq cedex (France); Ouddane, B., E-mail: [Universite Lille 1 (USTL), FRE CNRS 3298 Geosystemes, Equipe de Chimie Analytique et Marine, 59655 Villeneuve d' Ascq cedex (France); Mikkelsen, O. [Faculty of Natural Sciences and Technology, Department of Chemistry, 7491 Trondheim (Norway); Boughriet, A. [Universite d' Artois, I.U.T. de Bethune Departement de Chimie, Rue de l' Universite, B.P. 819, 62408 Bethune cedex (France)


    Research highlights: {yields} Behaviour and fate of metal contaminants in sediments (remobilisation, dredging ...). {yields} Implication of metal contaminations on biogeochemical processes in anoxic sediments. {yields} Impacts on the distribution of anthropogenic metal in sediments. - Abstract: The objective of the present work was to assess depth-related variations in the (bio)geochemical processes involved in anoxic sediments from the Deule river, and to examine particularly their impacts on the distribution of anthropogenically sourced metals. Anoxic sediment samples were sliced and analyzed to determine total concentrations vs. depth of elements and corresponding pore waters were analyzed to determine concentration profiles with depth of pH, Eh, alkalinity, O{sub 2}, dissolved organic carbon (DOC), and main inorganic anions and cations present in the medium. It was shown that rapid depletions of O{sub 2}, NO{sub 3}{sup -} and SO{sub 4}{sup 2-}, accompanied with HCO{sub 3}{sup -} generation and a sharp decrease in the redox potential occurred within the first centimeters of the surface sediment as a consequence of early diagenesis. Bacterial reductive dissolution of Mn(III and IV) and Fe(III) oxides/hydroxides to Mn(II) and Fe(II) accompanied by microbial degradation of organic matter took place as well, and resulted in trace metal increases in the pore water at levels that raised the possibility of mineral generation. Thermodynamic calculations predicted removal of metals from interstitial waters through combinations with carbonates and/or sulfides. These took place either by direct precipitation to form pure crystals, or by coprecipitation/sorption with/into calcite and with pyritic compounds. Chemical sequential extraction data were useful in this work to support, at least partially, some thermodynamic predictions concerning the existence of interactions between trace metals and carbonate and sulfide ions to generate (co)precipitates. Electron paramagnetic

  18. Early diagenesis and trace element accumulation in North American Arctic margin sediments

    Kuzyk, Zou Zou A.; Gobeil, Charles; Goñi, Miguel A.; Macdonald, Robie W.


    Concentrations of redox-sensitive elements (S, Mn, Mo, U, Cd, Re) were analyzed in a set of 27 sediment cores collected along the North American Arctic margin (NAAM) from the North Bering Sea to Davis Strait via the Canadian Archipelago. Sedimentary distributions and accumulation rates of the elements were used to evaluate early diagenesis in sediments along this section and to estimate the importance of this margin as a sink for key elements in the polar and global oceans. Distributions of Mn, total S and reduced inorganic S demonstrated that diagenetic conditions and thus sedimentary carbon turnover in the NAAM is organized regionally: undetectable or very thin layers (Canyon and Lancaster Sound; and thick layers (5-20 cm) of surface Mn enrichment occurred in the Beaufort Shelf, Canadian Archipelago, and Davis Strait. Inventories of authigenic S below the Mn-rich layer decreased about fivefold from Bering-Chukchi shelf and Barrow Canyon to Lancaster Sound and more than ten-fold from Bering-Chukchi shelf to Beaufort Shelf, Canadian Archipelago and Davis Strait. The Mn, total S and reduced inorganic S distributions imply strong organic carbon (OC) flux and metabolism in the Bering-Chukchi shelves, lower aerobic OC metabolism in Barrow Canyon and Lancaster Sound, and deep O2 penetration and much lower OC metabolism in the Beaufort Shelf, Canadian Archipelago, and Davis Strait. Accumulation rates of authigenic S, Mo, Cd, Re, and U displayed marked spatial variability along the NAAM reflecting the range in sedimentary redox conditions. Strong relationships between the accumulation rates and vertical carbon flux, estimated from regional primary production values and water depth at the coring sites, indicate that the primary driver in the regional patterns is the supply of labile carbon to the seabed. Thus, high primary production combined with a shallow water column (average 64 m) leads to high rates of authigenic trace element accumulation in sediments from the Bering

  19. Diagenesis of echinoderm skeletons: Constraints on paleoseawater Mg/Ca reconstructions

    Gorzelak, Przemysław; Krzykawski, Tomasz; Stolarski, Jarosław


    One of the most profound environmental changes thought to be reflected in chemical composition of numerous geological archives is Mg/Ca ratio of the seawater, which has varied dramatically throughout the Phanerozoic. Echinoderms that today typically form high magnesium calcite skeletons are increasingly being utilized as a proxy for interpreting secular changes in seawater chemistry. However, accurate characterization of the diagenetic changes of their metastable high magnesium calcite skeletons is a prerequisite for assessing their original, major-element geochemical composition. Here we expand the existing models of diagenesis of echinoderm skeleton by integration of various analytical methods that up to now rarely have been used to assess the diagenetic changes of fossil echinoderms. We validated the preservation of a suite of differently preserved echinoderm ossicles, mostly crinoids, ranging in age from the Cambrian through Recent. In 13 of 99 fossil echinoderm ossicles we found well-preserved porous microstructure (stereom), non-luminescent behaviour or blotchy dark color in cathodoluminescence, and distinct nanostructural features (layered and nanocomposite structure). Moreover, in representatives of such preserved samples, distribution of sulphates associated with organic matter is identical to those in Recent echinoderms. Only such ossicles, despite of local micrometer-scale diagenetic changes, were herein considered well-preserved, retaining their original major-element skeletal composition. By contrast, majority of samples show transformation to the stable low magnesium calcite that leads to obliteration of the primary geochemical and micro/nanostructural features and is accompanied with increase in cathodoluminescence emission intensity. Using only well-preserved fossil echinoderm samples, we found purely random variation in Mg/Ca in echinoderm skeletons through the observed time series; any periodicities in echinoderm skeletal Mg/Ca ratio which might

  20. Influence of diagenesis on the stable isotopic composition of biogenic carbonates from the Gulf of Tehuantepec oxygen minimum zone

    Blanchet, C. L.; Kasten, S.; Vidal, L.; Poulton, S. W.; Ganeshram, R.; Thouveny, N.


    In order to evaluate the influence of diagenetic and post-sampling processes on the stable oxygen and carbon isotope compositions of biogenic carbonates, we conducted a multiproxy study of organic-rich sediments from the eastern Pacific oxygen minimum zone. Core MD02-2520, which was retrieved from the Gulf of Tehuantepec (Mexico), has seasonal laminations and covers the last 40 kyr. Together with the presence of gypsum crystals and inorganic calcite aggregates, the occurrence of large excursions in the stable oxygen and carbon isotope records of both planktonic and benthic foraminifera (as large as +3‰ in δ18O and -5‰ in δ13C) point to significant secondary transformations. Storage-related gypsum precipitation was ruled out since it implies sulfide reoxidation by oxygen that triggers biogenic calcite dissolution, which proved to be of minor importance here. Instead, precipitation of authigenic calcite during early diagenesis appears to be the most likely process responsible for the observed isotopic excursions. The δ13C composition for inorganic calcite aggregates (-5 to -7‰) suggests a major contribution from anaerobic oxidation of organic matter. The δ34S composition for gypsum crystals (-10 to +15‰) suggests a major contribution from anaerobic reoxidation of authigenic sulfides, potentially involving reactions with metal oxides and sulfur disproportionation. A minor part of the gypsum might possibly have formed as a result of local pore water salinity increases induced by gas hydrate formation.

  1. Early diagenesis of phosphorus in continental margin sediments.

    Slomp, C.P.


    Most of the organic material in the oceans that reaches the sea floor is deposited on continental margins and not in the deep sea. This organic matter is the principal carrier of phosphorus (P) to sediments. A part of the organic material is buried definitely. The other part decomposes, resulting in

  2. Hypolyminetic Oxygen Depletion And Dynamics of P Binding Forms: Insights From Modeling Sediment Early Diagenesis Coupled With Automatic Parameter Estimation

    Shafei, Babak; Schmid, Martin; Müller, Beat; Chwalek, Thomas


    Sediment diagenesis can significantly impact on lake water quality through depleting hypolimnion oxygen and acting as a sink or source of nutrients and contaminants. In this study, we apply MATsedLAB, a sediment diagenesis module developed in MATLAB [1, 2] to quantify benthic oxygen consumption and biogeochemical cycling of phosphate (P) in lacustrine sediments of Lake Baldegg, located in central Switzerland. MATsedLAB provides an access to the advanced computational and visualization capabilities of the interactive programming environment of MATLAB. It allows for a flexible definition of non steady-state boundary conditions at the sediment-water interface (SWI), the model parameters as well as transport and biogeochemical reactions. The model has been extended to facilitate the model-independent parameter estimation and uncertainty analysis using the software package, PEST. Lake Baldegg represents an interesting case where sediment-water interactions control P loading in an eutrophic lake. It is of 5.2 km2 surface area and has been artificially aerated since 1982. Between 1960 and 1980, low oxygen concentrations and meromictic condition were established as a result of high productivity. Here, we use the cores for the measurements of anions and cations which were collected in April and June 2012 respectively from the deepest location (66 m), by Torres et al. (2013) to calibrate the developed model [3]. Depth profiles of thirty three species were simulated by including thirty mixed kinetic-equilibrium biogeochemical processes as well as imposing the fluxes of organic and inorganic matters along with solute concentrations at the SWI as dynamic boundary conditions. The diffusive transport in the boundary layer (DBL) above the SWI was included as the supply of O2 to the sediment surface can be diffusion-limited, and applying a constant O2 concentration at the sediment surface may overestimate O2 consumption. Benthic oxygen consumption was calculated as a function of

  3. The morphodynamics and sedimentology of large river confluences

    Nicholas, Andrew; Sambrook Smith, Greg; Best, James; Bull, Jon; Dixon, Simon; Goodbred, Steven; Sarker, Mamin; Vardy, Mark


    Confluences are key locations within large river networks, yet surprisingly little is known about how they migrate and evolve through time. Moreover, because confluence sites are associated with scour pools that are typically several times the mean channel depth, the deposits associated with such scours should have a high potential for preservation within the rock record. However, paradoxically, such scours are rarely observed, and the sedimentological characteristics of such deposits are poorly understood. This study reports results from a physically-based morphodynamic model, which is applied to simulate the evolution and resulting alluvial architecture associated with large river junctions. Boundary conditions within the model simulation are defined to approximate the junction of the Ganges and Jamuna rivers, in Bangladesh. Model results are supplemented by geophysical datasets collected during boat-based surveys at this junction. Simulated deposit characteristics and geophysical datasets are compared with three existing and contrasting conceptual models that have been proposed to represent the sedimentary architecture of confluence scours. Results illustrate that existing conceptual models may be overly simplistic, although elements of each of the three conceptual models are evident in the deposits generated by the numerical simulation. The latter are characterised by several distinct styles of sedimentary fill, which can be linked to particular morphodynamic behaviours. However, the preserved characteristics of simulated confluence deposits vary substantial according to the degree of reworking by channel migration. This may go some way towards explaining the confluence scour paradox; while abundant large scours might be expected in the rock record, they are rarely reported.

  4. Process sedimentology of submarine fan deposits - new perspectives

    Postma, George


    To link submarine fan process sedimentology with sand distribution, sand body architecture, texture and fabric, the field geologist studies sedimentary facies, facies associations (fan elements) and stratigraphy. Facies analysis resides on factual knowledge of modern fan morphodynamics and physical modelling of en-masse sediment transport. Where do we stand after 55 years of submarine research, i.e. the date when the first submarine fan model was launched by Arnold Bouma in 1962? Since that date students of submarine fans have worked on a number of important, recurring questions concerned with facies analysis of submarine successions in outcrop and core: 1. What type of sediment transport produced the beds? 2. What facies can be related to initial flow conditions? 3. What is the significance of grain size jumps and bounding surface hierarchy in beds consisting of crude and spaced stratification (traction carpets)? Do these point to multi flow events or to flow pulsations by one and the same event? 4. What facies associations relate to the basic elements of submarine fans? 5. What are the autogenic and allogenic signatures in submarine fans? Particularly in the last decade, the enormous technical advancement helped to obtain high-quality data from observations of density flows in modern canyons, deep basins and deep-water delta slopes (refs 1,2,3). In combination with both physical (refs 4,5) and numerical modelling (ref 6) these studies broke new ground into our understanding of density flow processes in various submarine environments and have led to new concepts of submarine fan building by super- and subcritical high-density flow (ref 7). Do these new concepts provide better answers to our recurrent questions related to the morphodynamics of submarine fans and prediction of sand body architecture? In discussing this open question, I shall 1. apply the new concepts to a modern and ancient example of a channel-lobe-transition-zone (ref 8); 2. raise the problem of

  5. Microfacies and diagenesis of Gua Bama limestone, Pahang Darul Makmur, Malaysia

    Joeharry, Nelisa Ameera Mohamed; Ali, Che Aziz; Leman, Mohd Shafeea; Mohamed, Kamal Roslan


    Gua Bama limestone hill in Lipis District, Pahang State is a well-known site for the hunt of Malaysian Permo-Triassic Boundary. This paper details the microfacies and diagenesis of limestone succession at Gua Bama outcrop as an early effort to constrain the desired Permo-Triassic Boundary. Six microfacies have been identified: mudstone, peloidal wackestone, bioclastic wackestone, radiolarian wackestone, intraclastic packstone, and peloidal packstone. The appearance of highly diverse benthic fauna in fragmented forms and the dominance of mudstone-wackestone microfacies prove that carbonates of Gua Bama were deposited in low-energy shallow marine environment. Gua Bama have been subjected to multiple diagenetic processes, namely cementation, compaction, neomorphism, and micritization. Based on diagenetic textures observed, it can be interpreted that Gua Bama limestone had undergone diagenesis within marine water phreatic zone and deep burial realms.

  6. Alkaline diagenesis and its influence on a reservoir in the Biyang depression

    QIU; Longwei; (邱隆伟); JIANG; Zaixing; (姜在兴); CAO; Yingchang; (操应长); QIU; Ronghua(邱荣华); CHEN; Wenxue; (陈文学); &; TU; Yangfa; (涂阳发)


    Alkaline diagnesis is a diagenetic process that a reservoir undergoes under an alkaline environment. Because of the influence of alkaline formation water, the most typical characteristics of diagnesis is that quartz is obviously dissolved, feldspar is massively enlarged, and less late carbonate cement is formed in the evolution of carbonate minerals. With the decrease of the alkalinity of the formation water in diagenesis, the quartz overgrowths become common. The change in the chemical characteristics of the formation water leads to a more complex distribution of reservoir porosity at different depths than that of the secondary porosity formed by classical acidic water. It also makes the B stage of early diagenesis the important development period of secondary porosity.

  7. Sedimentology of Martian Gravels from Mardi Twilight Imaging: Techniques

    Garvin, James B.; Malin, Michael C.; Minitti, M. E.


    Quantitative sedimentologic analysis of gravel surfaces dominated by pebble-sized clasts has been employed in an effort to untangle aspects of the provenance of surface sediments on Mars using Curiosity's MARDI nadir-viewing camera operated at twilight Images have been systematically acquired since sol 310 providing a representative sample of gravel-covered surfaces since the rover departed the Shaler region. The MARDI Twilight imaging dataset offers approximately 1 millimeter spatial resolution (slightly out of focus) for patches beneath the rover that cover just under 1 m2 in area, under illumination that makes clast size and inter-clast spacing analysis relatively straightforward using semi- automated codes developed for use with nadir images. Twilight images are utilized for these analyses in order to reduce light scattering off dust deposited on the front MARDI lens element during the terminal stages of Curiosity's entry, descent and landing. Such scattering is worse when imaging bright, directly-illuminated surfaces; twilight imaging times yield diffusely-illuminated surfaces that improve the clarity of the resulting MARDI product. Twilight images are obtained between 10-30 minutes after local sunset, governed by the timing of the end of the no-heat window for the camera. Techniques were also utilized to examine data terrestrial locations (the Kau Desert in Hawaii and near Askja Caldera in Iceland). Methods employed include log hyperbolic size distribution (LHD) analysis and Delauney Triangulation (DT) inter-clast spacing analysis. This work extends the initial results reported in Yingst et al., that covered the initial landing zone, to the Rapid-Transit Route (RTR) towards Mount Sharp.

  8. A novel method to assess the effect of diagenesis on fossil teeth: Rare earth element signatures

    WEN Xingyue; WANG Chengshan; HUANG Chengmin; BAI Song; ZHANG Qing


    An attempt was made to test the validity of the signatures of rare earth elements (REE) as a tool to judge the effect of diagenesis on fossil teeth.Sample REE contents and features of fossil teeth and sediments from Jinsha Relics,Sichuan,Southwest China were analyzed.The difference in REE content between fossil teeth is significantly greater than that between sediments at the Jinsha Relics.Chondrite-normalized REE patterns showed that obvious LREE enrichment and strong Ce and HREE depletion occurred in all fossil teeth samples.Meanwhile δCe and δEu values varied more dramatically in fossil teeth than in sediments.Accordingly,low content,LREE enrichment,strong Ce depletion,the significantly positive correlation between LREE/HREE and δCe,and unchanged (La/Yb)N demonstrated that the fossil teeth from Jinsha Relics have not been contaminated by diagenesis.The REE signature might be a potential proxy to assess the effect of diagenesis on fossil teeth.

  9. Relation between facies, diagenesis, and reservoir quality of Rotliegende reservoirs in north Germany

    David, F.; Gast, R.; Kraft, T. (BEB Erdgas Erdol GmbH, Hannover (Germany))


    In north Germany, the majority of Rotliegende gas fields is confined to an approximately 50 km-wide east-west-orientated belt, which is situated on the gently north-dipping flank of the southern Permian basin. Approximately 400 billion m[sup 3] of natural gas has been found in Rotliegende reservoir sandstones with average porosities of depths ranging from 3500 to 5000 m. Rotliegende deposition was controlled by the Autunian paleo-relief, and arid climate and cyclic transgressions of the desert lake. In general, wadis and large dunefields occur in the hinterland, sebkhas with small isolate dunes and shorelines define the coastal area, and a desert lake occurs to the north. The sandstones deposited in large dunefields contain only minor amounts of illite, anhydrite, and calcite and form good reservoirs. In contrast, the small dunes formed in the sebkha areas were affected by fluctuations of the desert lake groundwaters, causing the infiltration of detrital clay and precipitation of gypsum and calcite. These cements were transformed to illite, anhydrite, and calcite-II during later diagenesis, leading to a significant reduction of the reservoir quality. The best reservoirs occur in the shoreline sandstones because porosity and permeability were preserved by early magnesium-chlorite diagenesis. Since facies controls diagenesis and consequently reservoir quality, mapping of facies also indicates the distribution of reservoir and nonreservoir rocks. This information is used to identify play area and to interpret and calibrate three-dimensional seismic data.

  10. Diagenesis of Oligocene continental sandstones in salt-walled mini-basins-Sivas Basin, Turkey

    Pichat, Alexandre; Hoareau, Guilhem; Callot, Jean-Paul; Ringenbach, Jean-Claude


    The recent discovery of Oligo-Miocene salt-walled continental mini-basins in the Sivas Basin (central Anatolia, Turkey) provides the opportunity to unravel the influence of halokinesis on the diagenesis of continental mini-basin infilling. In this study, petrographic and geochemical analyses are used to define the diagenetic sequences recorded by two mini-basins filled mainly by fluvial clastic sediments of the upper Oligocene Karayün Formation. The initial diagenetic features are those commonly encountered in arid to semi-arid continental environments, i.e. clay infiltration, hematite precipitation and vadose calcite cement. Other early cements were strongly controlled by sandstone detrital composition in the presence of saline/alkaline pore water. In feldspathic litharenites and lithic arkoses, near-surface alterations were characterized by the precipitation of analcime (up to 10%), albite and quartz overgrowths (burial diagenesis which prevented further mesogenetic alteration phenomena such as compaction. In feldsarenites, early diagenesis differs by (i) the absence of analcime, (ii) better developed albite cements, (iii) thin smectite-illite coatings forming pore linings and (iv) patchy calcite cementation (burial, and result in a significant degradation of porosity.

  11. Spatiotemporal variability of sedimentology and morphology in the East Frisian barrier island system

    Herrling, Gerald; Winter, Christian


    The highly dynamic East Frisian barrier island system (southern North Sea) is characterized by a complex morphology of tidal inlets, ebb-tidal deltas and foreshore beaches that reacts to storms and fair-weather conditions with characteristic patterns of sediment grain-size distributions. The morphological and sedimentological response to varying hydrodynamic conditions yet occurs in short time spans that are not covered by common monitoring strategies with measuring intervals typically of years. This study applies process-based numerical modelling with multiple sediment fractions to interpolate morphological states in time between bathymetrical surveys conducted in the summer months of 2004 and 2006. Morphodynamic simulations driven by real-time boundary conditions of tides, wind and waves are carried out for a representative period of 2 years. The spatiotemporal variability of the nearshore sedimentology and morphology is assessed by graded ranges of bed dynamics (i.e. bed elevation range) and the definition of sediment grain-size variability (i.e. mean diameter range). The effect of storm events and timescales of the sedimentological adaptation after storms to typical fair-weather conditions are exemplified at an ebb-tidal delta lobe where the morphological and sedimentological variability is found to be largest in the study area. The proposed method may serve to identify areas of high sedimentological and morphological activity for system understanding or in the framework of coastal monitoring strategies.

  12. Diagenesis and porosity evolution of tight sand reservoirs in Carboniferous Benxi Formation, Southeast Ordos Basin

    Hu, Peng; Yu, Xinghe; Shan, Xin; Su, Dongxu; Wang, Jiao; Li, Yalong; Shi, Xin; Xu, Liqiang


    The Ordos Basin, situated in west-central China, is one of the oldest and most important fossil-fuel energy base, which contains large reserves of coal, oil and natural gas. The Upper Palaeozoic strata are widely distributed with rich gas-bearing and large natural gas resources, whose potential is tremendous. Recent years have witnessed a great tight gas exploration improvement of the Upper Paleozoic in Southeastern Ordos basin. The Carboniferous Benxi Formation, mainly buried more than 2,500m, is the key target strata for hydrocarbon exploration, which was deposited in a barrier island and tidal flat environment. The sandy bars and flats are the favorable sedimentary microfacies. With an integrated approach of thin-section petrophysics, constant velocity mercury injection test, scanning electron microscopy and X-ray diffractometry, diagenesis and porosity evolution of tight sand reservoirs of Benxi Formation were analyzed in detail. The result shows that the main lithology of sandstone in this area is dominated by moderately to well sorted quartz sandstone. The average porosity and permeability is 4.72% and 1.22mD. The reservoirs of Benxi Formation holds a variety of pore types and the pore throats, with obvious heterogeneity and poor connection. Based on the capillary pressure curve morphological characteristics and parameters, combined with thin section and phycical property data, the reservoir pore structure of Benxi Formation can be divided into 4 types, including mid pore mid throat type(I), mid pore fine throat type(II), small pore fine throat type(III) and micro pro micro throat type(Ⅳ). The reservoirs primarily fall in B-subsate of middle diagenesis and late diagenesis, which mainly undergo compaction, cmentation, dissolution and fracturing process. Employing the empirical formula of different sorting for unconsolideated sandstone porosity, the initial sandstone porosity is 38.32% on average. Quantitative evaluation of the increase and decrease of

  13. Rock magnetic property of gravity core CSH1 from the northern Okinawa Trough and the effect of early diagenesis


    Detailed rock magnetic investigations were undertaken at 2~4 cm interval for the gravity core CSH1 (with a length of 17.36 m) from the northern Okinawa Trough. Time-scale of the core was constructed by two characteristic tephras and foraminferal assemblages, indicating an age of 50 ka for the bottom of the core. Except for three tephras and abrupt decrease in surface, there are little changes in all kinds of rock magnetic parameters that can be correlated to the climate change for the last 50 ka. Different from the common sediments, most S-ratios (S equals the negative ratio of IRM-0.3T to SIRM, which is an indicator of low coercivity content)of the sediments are smaller than 0.9, which implies a substantial amount of magnetic minerals with high coercivity. The existence of iron sulphide (greigite or pyrrhotite) is revealed by representative susceptibility-temperature curves showing 200~350 ℃ Curie temperature in addition to 580 ℃ of magnetite, and also by awful smell during heating and dark heating products. Both the occurrence of authigenic iron sulphide and quick decrease of magnetic parameters near the surface clearly show that sediments from Core CSH1 have undergone early diagenesis. The featureless magnetic changes of the whole core except for three tephras mean that the post-depositonal alteration is so strong that most original signals have been destroyed. For the same reason, the organic matter in sediment and sulphate in pore water must have been consumed along with dissolution, precipitation of iron and manganese happening sequencially during the redox reaction series. Great caution must be taken when using these altered chemical parameters for the interpretation of climatic changes.

  14. Sedimentology and geochemistry of recent alluvium of the wadi Beht mean (Furrow south western Rif, Morocco: dynamics of implementation and hydrological and climatic meanings ”

    Ahmed LAABIDI


    Full Text Available The watershed of the river Beht is located northwest of Morocco and occupies the southwestern part of the Sebou basin. This study focuses on the sedimentological and geochemical analysis of current alluvial floodplain and meandering filling abandoned Middle Beht. The results revealed that the sediments exhibit an alkaline pH, low levels of carbonates, low values of the electrical conductivity and relatively high contents of organic matter mostly in the finest sediment. Deposits are organized in grano-decreasing repetitive elementary sequences much more expressed and fines in meandering filling abandoned deposits, which function as ephemeral lakes, as in those of the floodplain. They are the expression of the sedimentological variation of hydrodynamics related to the succession of flood-related flood recession cycles themselves with climate change. They are set up on the often rocky deposits texture background meandering channels and bars. The sequence of these basic sequences, sandy-silty clay at the base and silty-sandy clay on top, gives larger sequences grano-decreasing.

  15. Boron and diagenesis: Questioning the fidelity of Snowball δ11B excursions

    Foster, G. L.; Stewart, J.; Gutjahr, M.; Pearce, F.; Swart, P. K.


    Large negative carbon (δ13C) and boron (δ11B) isotope excursions (both >6‰) within the widely distributed Neoproterozoic "Snowball Earth" cap carbonates are interpreted as evidence for considerable perturbation of the carbon cycle and the associated reduction, then recovery of global ocean pH. Yet, before conclusive interpretations may be drawn, isotopic data must first be shown to be primary in origin and non-diagenetic. Recent studies of Quaternary carbonate platform sediments from a number of locations worldwide reveal δ13C excursions of similar magnitude and distribution to the "Snowball Earth" excursions. However, these recent analogues were formed following eustatic sea level fall and exposure of recent carbonates to meteoric diagenesis (Swart and Kennedy, 2012). Here we present δ11B and B/Ca data from Pleistocene-aged carbonate platform sediments recovered by the Clino Core from the Bahamas to examine the effects of diagenesis on the boron system. We find that within the interval of meteoric diagenesis the δ11B of bulk carbonate is substantially reduced by approximately 6‰ in conjunction with a drop in B/Ca of 90%. These isotopic and elemental down-core patterns are strikingly similar to those reported for δ11B and B/Ca in the cap carbonates of the Neoproterozoic snowball Earth events (Kasemann et al., 2005; Kasemann et al., 2010). Our results may therefore question the primary nature of "Snowball Earth" isotope excursions. We recommend more rigorous assessment of the diagenetic history of these ancient carbonates to ensure palaeoclimatological interpretations are robust.

  16. Reductive diagenesis, magnetite dissolution, greigite growth and paleomagnetic smoothing in marine sediments: A new view

    Rowan, Christopher J.; Roberts, Andrew P.; Broadbent, Thomas


    In many anoxic sedimentary environments, the onset of sulfate reduction, and pyritization of detrital iron-bearing minerals, leads to a precipitous decline in magnetic mineral concentration during early diagenesis. The usefulness of the surviving paleomagnetic record in such environments is usually argued to depend on how much of the primary detrital magnetic assemblage survives diagenetic dissolution. Detailed rock magnetic and electron microscope analyses of rapidly deposited (~ 7 cm/kyr) latest Pleistocene-Holocene sediments from the continental margins of Oman (22°22.4'N, 60°08.0'E) and northern California (38°24.8'N, 123°58.2'W) demonstrate that pyritization during early diagenesis also leads to the progressive down-core growth of the ferrimagnetic iron sulfide greigite. Greigite growth begins with nucleation of large concentrations of superparamagnetic (SP) nanoparticles at the inferred position of the sulfate-methane transition, which can explain the apparently paradoxical suggestion that diagenetically reduced sediments contain enhanced concentrations of SP particles. Looping of hysteresis parameters on a "Day" plot records the dissolution of single domain (SD) (titano-)magnetite and the formation of SP greigite, which then slowly and progressively grows through its SD blocking volume and acquires a stable paleomagnetic signal. This looping trend is also evident in data from several published records (Oregon margin, Korea Strait, Japan Sea, Niger Fan, Argentine margin, and the Ontong-Java Plateau), indicating that these processes may be widespread in reducing environments. Our observations have profound implications for paleomagnetic records from sulfate-reducing environments. The paleomagnetic signal recorded by greigite is offset from the age of the surrounding sediments by 10's of kyr, and ongoing growth of greigite at depth results in smoothing of the recorded signal over intervals of 10's to 100's of kyr. We therefore expect the presence of

  17. Testing and Validation Studies of the NSMII-Benthic Sediment Diagenesis Module


    di m en t L ay er 2 Diagenesis POCG1,2 CH4, H2S, NH3, CO2 POCG3,2 POCG2,2 PONG1,2 PONG3,2 PONG2,2 POPG1,2 POPG3,2 POPG2,2 PON POP POC Algae , POC...Warren P. Lorentz, Chief, EPED; and Dr. Beth Fleming, Director, ERDC-EL. At the time of publication, COL Bryan S. Green was Commander of ERDC, and...benthic algae , nitrogen, phosphorus, and carbon cycles, carbonaceous bio- chemical oxygen demand, dissolved oxygen, and pathogen. The constitu- ents

  18. Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard) - environmental and climatic implications for the late Holocene

    Oliva, M.; Vieira, G.; Pina, P.; Pereira, P.; Neves, M.; Freitas, M. C.


    Ice wedges are widespread periglacial features in the landscape of Adventdalen, Svalbard. The networks of ice wedges have created areas with well-developed polygonal terrains in the lowest fluvial terraces in this valley. We have examined the sedimentological characteristics of the northern and southern banks of the Advent river for palaeoenvironmental purposes. The base of two sedimentary sections reported radiocarbon dates of 3.3 and 3.9 ka BP, respectively. The northern site is constituted by three very different lithostratigraphical units, which suggests that their formation should be related to different environmental and climate conditions. By contrast, the southern section shows a rather homogeneous composition, with no significant variations in grain size and organic matter content. In both cases the uppermost sediments are constituted by a thick aeolian deposit. According to our data, warmer climate conditions may have prevailed during the mid Holocene until 3.3 ka BP with widespread peat formation in the valley bottom. Subsequently, a period with alternating soil formation and aeolian sedimentation took place from 3 to 2.5 ka BP, probably due to increasing climatic severity. During the last millennium a long-term cooling trend has favoured aeolian deposition in the lowest part of Adventdalen.

  19. Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard. Environmental and climatic implications for the Late Holocene

    M. Oliva


    Full Text Available Ice-wedges are widespread periglacial features in the landscape of Adventalen, Svalbard. The networks of ice-wedges have created areas with well-developed polygonal terrains in the lowest fluvial terraces in this valley. We have examined the sedimentological characteristics of the northern and southern banks of the Advent river for palaeoenvironmental purposes. The base of two sedimentary sections reported radiocarbon dates of 3.3 and 3.9 ka cal BP, respectively. The northern site is constituted by three very different lithostratigraphical units, which suggests that their formation should be related to different environmental and climate conditions. By contrast, the southern section shows a rather homogeneous composition, with no significant variations in grain size and organic matter content. In both cases the uppermost sediments are constituted by a thick aeolian deposit. According to our data, warmer climate conditions may have prevailed during the Mid Holocene until 3.3 ka cal BP with widespread peat formation in the valley bottom. Subsequently, a period with alternating soil formation and aeolian sedimentation took place from 3 to 2.5 ka cal BP, probably due to increasing climatic severity. During the last millennium a long-term cooling trend has favoured aeolian deposition in the lowest Adventalen valley.

  20. Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard). Environmental and climatic implications for the Late Holocene

    Oliva, M.; Vieira, G.; Pina, P.; Pereira, P.; Neves, M.; Freitas, M. C.


    Ice-wedges are widespread periglacial features in the landscape of Adventalen, Svalbard. The networks of ice-wedges have created areas with well-developed polygonal terrains in the lowest fluvial terraces in this valley. We have examined the sedimentological characteristics of the northern and southern banks of the Advent river for palaeoenvironmental purposes. The base of two sedimentary sections reported radiocarbon dates of 3.3 and 3.9 ka cal BP, respectively. The northern site is constituted by three very different lithostratigraphical units, which suggests that their formation should be related to different environmental and climate conditions. By contrast, the southern section shows a rather homogeneous composition, with no significant variations in grain size and organic matter content. In both cases the uppermost sediments are constituted by a thick aeolian deposit. According to our data, warmer climate conditions may have prevailed during the Mid Holocene until 3.3 ka cal BP with widespread peat formation in the valley bottom. Subsequently, a period with alternating soil formation and aeolian sedimentation took place from 3 to 2.5 ka cal BP, probably due to increasing climatic severity. During the last millennium a long-term cooling trend has favoured aeolian deposition in the lowest Adventalen valley.

  1. Sedimentology of the Paestum travertines, Salerno, Southern Italy

    Anzalone, E.; Ferreri, V.; D'Argenio, B.


    forming the town wall between Porta Sirena and Porta Giustizia (southern-eastern side of Paestum) and in the civil and sacred architecture. The time-space relationships among the above lithofacies associations clearly emerge in the Porta Marina area both in the Greek walls of the ancient town (slope and swamp facies) and in the outcropping travertine substrate (slope and waterfall deposits). Based on the above sedimentological results, it may be inferred that, like other ambient temperature travertine systems studied in southern Italy, the Paestum travertine growth developed over a gentle slope surface (in our case dipping to the west), laterally evolving into rapid and waterfall deposits. At the same time, the aggradational growth of the travertine system resulted in a flattened summit area with widespread swamp and marsh environments. The ruins of Paestum, including the lower parts of sacred and civil buildings as well as town roads and walls, are even today largely covered by recent semi-coherent travertines (tufa), originating from waters that encrusted and then "fossilized" a large part of the town. Inside the town walls, these materials were pedogenized and nowadays are largely cultivated around and within the archeological area. A portion of these deposits was removed during the excavations of the beginning of last century, but traces of them may still be observed in different parts of the ancient town. Like the foundation travertines, the recent deposits are mainly made up of calcareous encrustations. Gastropods, ostracods and other organisms typical of terrestrial humid environments may be found in the phytoclastic textures. Usually, they are weakly cemented and at places incorporate different materials, including brick, wood and coal fragments. These sediments patchy cover the town within the wall perimeter, for a few decimetres in the sacred areas, but reaching over 4 meters downhill and outside the walls: a process of "fossilization" that appears to have been

  2. Experimental Simulation of Dolomite Dissolution Under Burial Diagenesis Conditions and Thermodynamic Interpretation

    黄思静; 肖林萍; 等


    Simulating experiments on dolomite dissolution by acetic acid were made under burial diagenesis conditions,at temperatures ranging from 75℃to 130℃ and pressures from 20 MPA to 30MPa,The results show that the dissolution rate of dolomite increased rapidly with increasing temperature and prssure,From 75℃/Mpa to 130℃/30 MPa,the total amount of released ca and Mg increased from 32.98mg/L to 337.9mg/L,over one order of magnitude in difference,Thermodynamic calculation indicates that the increment of Gibbs free energy (ΔG) of the chemical reaction decreases with increasing temperature and pressure.This thermodynamic result is consistent with the experimental result.Based on the Experimental is suggested that secondary prosities formed by dolomite dissolution under conditions of deep burial diagenesis should be more common than those under epigenesis and shallow burial conditions,and therefore dolomite reservoires in the formations that have been deeply buried should be more abundant than in the formations that have only been shallowly buried.

  3. Coral zonation and diagenesis of an emergent Pleistocene patch reef, Belize, Central America

    Lighty, R.G.; Russell, K.L.


    Transect mapping and petrologic studies reveal a new depositional model and limited diagenesis of a well-exposed Pleistocene reef outcrop at Ambergris Cay, northern Belize. This emergent shelf-edge reef forms a rocky wave-washed headland at the northern terminus of the present-day 250 km long flourishing Belize Barrier Reef. Previously, the Belize reef outcrop was thought to extend southward in the subsurface beneath the modern barrier reef as a Pleistocene equivalent. The authors study indicate that this outcrop is a large, coral patch reef and not part of a barrier reef trend. Sixteen transects 12.5 m apart described in continuous cm increments from fore reef to back reef identified: extensive deposits of broken Acropora cervicornis; small thickets of A. palmata with small, oriented branches; and muddy skeletal sediments with few corals or reef rubble. Thin section and SEM studies show three phases of early submarine cementation: syntaxial and rosette aragonite; Mg-calcite rim cement and peloids; and colloidal Mg-calcite geopetal fill. Subaerial exposure in semi-arid northern Belize caused only minor skeletal dissolution, some precipitation of vadose whisker calcite, and no meteoric phreatic diagenesis. Facies geometry, coral assemblages, lack of rubble deposits, coralline algal encrustations and Millepora framework, and recognition of common but discrete submarine cements, all indicate that this Pleistocene reef was an isolated, coral-fringed sediment buildup similar to may large patch reefs existing today in moderate-energy shelf environments behind the modern barrier reef in central and southern Belize.

  4. Reactive transport in surface sediments. II. Media: an object-oriented problem-solving environment for early diagenesis

    Meysman, F.J.R.; Middelburg, J.J.; Herman, P.M.J.; Heip, C.H.R.


    The MEDIA (Modelling Early DIAgenesis) software package comprises a flexible and extensible software system that provides problem-solving assistance for simulating 1D reactive transport in surface sediments. MEDIA allows multiple diagenetic models to be built by extending a model template with new m

  5. Carbonate mound evolution and coral diagenesis viewed by U-series dating of deep water corals

    Frank, N.; Ricard, E.; Blamart, D.; van der Land, C.; Colin, C.; Foubert, A.; van Rooij, D.; van Weering, T.


    U-series dating of constructional deep sea corals is a powerful tool to reconstruct the evolution of carbonate mound sediments driven by coral growth, sediment trapping and diagenesis. Here we have investigated in great detail the time framework of constructional corals such as L. pertusa and M. oculata on 5 different mounds of the eastern North Atlantic (on Rockall Bank and in Porcupine Seabight) taken at variable depth and location (610 to 880m water depth). Periods favorable for coral growth are the Holocene and prior interglacials such as marine isotope stage 5 and 7, while glacial coral growth seems inhibited or extremely reduced. Coral development is almost continuous throughout the Holocene since mound re-colonization about 10,500 years ago. Mound accumulation rates vary between 20 and 220 cm/kyr determined from the coral age - depth relationship in each core. Those changes are most likely driven by changes between horizontal and vertical mound accumulation, food supply and ocean circulation. In addition, coral dating allowed to identify an important erosional event recorded in core MD01-2455G from Rockall Bank. Here a 1m thick sediment layer containing ancient corals likely from the start of Holocene re-colonization was displaced (collapsed) from further upslope on top of younger corals of ~2500 to 3000 years age. Prior to the initiation of coral growth diagenesis occurred frequently resulting in (1) the construction of so called carbonate hardgrounds and/or (2) the dissolution of the pre-Holocene coral framework. Solely, the deepest selected core in Porcupine Seabight (MD01-2463G at 880m depth) reveals coral re-colonization on an undisturbed ancient reef structure that dates back to 250,000 years. Diagenesis of earlier coral reef generations leading to coral dissolution leads to a loss of magnetic susceptibility and open system behavior of the coral skeletons with respect to U-series dating. While the processes causing such diagenetic layers are barely

  6. Provenance and diagenesis of the evaporite-bearing Burns formation, Meridiani Planum, Mars

    McLennan, S.M.; Bell, J.F.; Calvin, W.M.; Christensen, P.R.; Clark, B. C.; de Souza, P.A.; Farmer, J.; Farrand, W. H.; Fike, D.A.; Gellert, Ralf; Ghosh, A.; Glotch, T.D.; Grotzinger, J.P.; Hahn, B.; Herkenhoff, K. E.; Hurowitz, J.A.; Johnson, J. R.; Johnson, S.S.; Jolliff, B.; Klingelhofer, G.; Knoll, A.H.; Learner, Z.; Malin, M.C.; McSween, H.Y.; Pocock, J.; Ruff, S.W.; Soderblom, L.A.; Squyres, S. W.; Tosca, N.J.; Watters, W.A.; Wyatt, M.B.; Yen, A.


    Impure reworked evaporitic sandstones, preserved on Meridiani Planum, Mars, are mixtures of roughly equal amounts of altered siliciclastic debris, of basaltic provenance (40 ?? 10% by mass), and chemical constituents, dominated by evaporitic minerals (jarosite, Mg-, Ca-sulfates ?? chlorides ?? Fe-, Na-sulfates), hematite and possibly secondary silica (60 ?? 10%). These chemical constituents and their relative abundances are not an equilibrium evaporite assemblage and to a substantial degree have been reworked by aeolian and subaqueous transport. Ultimately they formed by evaporation of acidic waters derived from interaction with olivine-bearing basalts and subsequent diagenetic alteration. The rocks experienced an extended diagenetic history, with at least two and up to four distinct episodes of cementation, including stratigraphically restricted zones of recrystallization and secondary porosity, non-randomly distributed, highly spherical millimeter-scale hematitic concretions, millimeter-scale crystal molds, interpreted to have resulted from dissolution of a highly soluble evaporite mineral, elongate to sheet-like vugs and evidence for minor synsedimentary deformation (convolute and contorted bedding, possible teepee structures or salt ridge features). Other features that may be diagenetic, but more likely are associated with relatively recent meteorite impact, are meter-scale fracture patterns, veins and polygonal fractures on rock surfaces that cut across bedding. Crystallization of minerals that originally filled the molds, early cement and sediment deformation occurred syndepositionally or during early diagenesis. All other diagenetic features are consistent with formation during later diagenesis in the phreatic (fluid saturated) zone or capillary fringe of a groundwater table under near isotropic hydrological conditions such as those expected during periodic groundwater recharge. Textural evidence suggests that rapidly formed hematitic concretions post

  7. Sedimentology and chemostratigraphy of a Valanginian carbonate succession from the Baja Guajira Basin, northern Colombia

    Silva-Tamayo, Juan Carlos; Ramirez, Catalina; Lara, Mario; Sial,Alcides Nobrega; Trujillo, David; Salazar, Edward


    ABSTRACT: The Kesima Member of the Palanz Formation constitutes the first record of Cretaceous marine sedimentation along the Baja Guajira Basin, northern Colombia. Sedimentologic and petrographic analyses suggest a deposition along a coral reef dominated rimmed carbonate platform. 87Sr/86Sr values between 0.707350 and 0.707400 suggest a Valanginian (136 - 132 Ma) depositional age for the Kesima Member. A positive anomaly on the δ13C values of ~2.2‰ suggests that this rimmed carbon...

  8. 19th International Sedimentological Congress 2014 in Geneva:Theme 12—Palaeogeography


    <正>At the forthcoming 19th International Sedimentological Congress(ISC2014)in Geneva,Switzerland,August 18-24,2014,the Editorial Committee of the Journal of Palaeogeography(JoP)will host Theme 12—Palaeogeography.For those who will attend ISC2014,please pay attention to the following information about this theme.1.Conveners:Zhong-Qiang Chen(China University of Geosciences(Wuhan),

  9. First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm at Fort Myers Beach, Florida


    Harbor in 1992 and 1993 resulted in a nearshore berm disposal in Port Canaveral, Florida, offshore of Cocoa Beach. Bodge (1994) evaluated the...samples. The carbonate grains are mostly shell debris. Table 2 provides an example summary of the sedimentological characteristics across a beach...located a 3-6) and f the berm ine sand, a shell debri . Similar to medium sh ly sorted ve e 11 shows a southeas Profile Sou t the toe of offshore (F

  10. Carbonate chemistry in sediment porewaters of the Rhône River delta driven by early diagenesis (northwestern Mediterranean)

    Rassmann, Jens; Lansard, Bruno; Pozzato, Lara; Rabouille, Christophe


    The Rhône River is the largest source of terrestrial organic and inorganic carbon for the Mediterranean Sea. A large fraction of this terrestrial carbon is either buried or mineralized in the sediments close to the river mouth. This mineralization follows aerobic and anaerobic pathways, with a range of impacts on calcium carbonate precipitation and dissolution in the sediment near the sediment-water interface. This study focuses on the production of dissolved inorganic carbon (DIC) and total alkalinity (TA) by early diagenesis, consequential pH variations and the effect on calcium carbonate precipitation or dissolution. The sediment porewater chemistry was investigated along a transect from the Rhône River outlet to the continental shelf. TA and concentrations of DIC, SO42- and Ca2+ were analyzed on bottom waters and extracted sediment porewaters, whereas pH and oxygen concentrations were measured in situ using microelectrodes. The average oxygen penetration depth into the sediment was 1.7 ± 0.4 mm close to the river mouth and 8.2 ± 2.6 mm in the continental shelf sediments, indicating intense respiration rates. Diffusive oxygen fluxes through the sediment-water interface ranged between 3 and 13 mmol O2 m-2 d-1. In the first 30 cm of the sediment, TA and DIC porewater concentrations increased with depth up to 48 mmol L-1 near the river outlet and up to 7 mmol L-1 on the shelf as a result of aerobic and anaerobic mineralization processes. Due to aerobic processes, at all stations pH decreased by 0.6 pH units in the oxic layer of the sediment accompanied by a decrease of the saturation state regarding calcium carbonate. In the anoxic layer of the sediments, sulfate reduction was the dominant mineralization process and was associated with an increase of porewater saturation state regarding calcium carbonate. Ultimately anoxic mineralization of organic matter caused calcium carbonate precipitation demonstrated by a large decrease in Ca2+ concentration with depth in

  11. Diagenesis of Holocene reef and associated beachrock of certain coral islands, Gulf of Mannar, India: Implication on climate and sea level

    S Kkrishna Kumar; N Chandrasekar; P Seralathan; J Dajkumar Sahayam


    The reef and associated beachrock from certain Gulf of Mannar islands (Rameswaram, Kurusadai, Shingle and Appa Island) were studied to assess the diagenetic evidences. Sixty samples were collected from marine terraces and reef platforms. The samples comprised of coral rubbles, shell fragments and lithic fractions. The presence of corals in the form of framework or isolated patches on the reef flat suggests the rapid increase of accommodation and probably absence of terrigenous and siliciclastic inputs. Moreover, the massive coral heads above the transgressive phase suggest the maximum flooding and relatively deepest facies. The freshwater dissolution, association of marine and meteoric cements suggest the semiarid climatic condition with marine diagenesis during sea level lowstands and recharge of freshwater lenses during periodic rainfalls. In addition, the interaction of these mixed carbonate, siliciclastic sediments results in silicification of carbonate components. The reef associated beachrock were deposited in low energy environment with some amount of terrigenous matters derived from Precambrian basement rocks and transported into reef area by ephemeral streams and longshore sediment transport. The incorporation of coral fragments within the siliciclastic sediments are most probably due to the erosion and re-deposition of the sediments.

  12. Carbonate cement stratigraphy and timing of diagenesis in a Miocene mixed carbonate-clastic sequence, offshore Sabah, Malaysia: constraints from cathodoluminescence, geochemistry, and isotope studies

    Yamin Ali, Mohammad


    A mixed carbonate-clastic sequence is one of several Miocene hydrocarbon-bearing reservoirs in the northwestern Sabah Basin. This sequence consists of bioclast-rich sandstones interpreted as prograding storm shoal deposits. The sequence contains a complex variety of carbonate nodules. The sequence has undergone nine stages of cementation that completely occluded pores. Each stage represents a distinctive cement texture, precipitating at specific temperatures and burial conditions. The diagenetic evolution began with a syndepositional iron-free marine calcite (Ca1), followed by an early methane-derived dolomite (Do1), bladed calcite (Ca2), blocky, vein-filling Fe-calcites ({Ca3}/{Ca4}, clay mineral-associated dolomite (Do2), Fe-dolomite and ankerite ({Do3}/{Do4}, and late iron-rich calcite (Ca5). Each stage of cement has distinctive Sr2+, Mn2+, Mg2+, Fe2+, Ca2+, and Na+ contents, reflecting changes in the palaeo-porefluid systems with time. The cements are correlatable over the whole study area. Precipitation occurred from very early to late stages of diagenesis at near surface to 2.0 km depths. With progressive burial and temperature increase, oxygen isotope values become strongly negative (stage Ca4: δ13C = -0.5%. PDB, δ18O = -5.7%. PDB). The cements were precipitated at 20-75°C. The source of carbon varies from marine dissolved carbonates to fermentation of organic matter, methane, meteoric waters, and possibly hydrothermal fluids. Strontium isotope dating of Do1 (with δ13C = -32.5%. PDB, δ18O = +2.60%. PDB) and Do2 (δ13C = 3.0%. PDB; δ18O = -2.5%. PDB) dolomites indicates that these dolomitization events took place at 10.5 Ma and 8.9 Ma, respectively, assuming precipitation within a completely open seawater system. The Do1 dolomite was precipitated from a methane-derived brine at the boundary between the Serravallian and Tortonian stages after major uplift, and induced faulting, at a sea-level lowstand. The Do2 dolomite was precipitated during

  13. Microfacies and diagenesis of the reefal limestone, Callovian Tuwaiq Mountain Limestone Formation, central Saudi Arabia

    EL-Sorogy, Abdelbaset S.; Almadani, Sattam A.; Al-Dabbagh, Mohammad E.


    In order to document the microfacies and diagenesis of the reefal limestone in the uppermost part of the Callovian Tuwaiq Mountain Limestone Formation at Khashm Al-Qaddiyah area, central Saudi Arabia, scleractinian corals and rock samples were collected and thin sections were prepared. Coral framestone, coral floatstone, pelloidal packstone, bioclastic packstone, bioclastic wacke/packstone, algal wackestone and bioclastic foraminiferal wacke/packstone were the recorded microfacies types. Cementation, recrystallization, silicification and dolomitization are the main diagenetic alterations affected the aragonitic skeletons of scleractinian corals. All coral skeletons were recrystallized, while some ones were dolomitized and silicified. Microfacies types, as well as the fossil content of sclearctinian corals, bivalves, gastropods, brachiopods and foraminifera indicated a deposition in environments ranging from shelf lagoon with open circulation in quiet water below wave base to shallow reef flank and organic build up for the uppermost reefal part of the Tuwaiq Formation in the study area.

  14. How burial diagenesis of chalk sediments controls sonic velocity and porosity

    Fabricius, Ida Lykke


    to the progress of burial diagenesis of chalk, which is revised as follows: Newly deposited carbonate ooze and mixed sediments range in porosity from 60 to 80%, depending on the prevalence of hollow microfossils. Despite the high porosity, these sediments are not in suspension, as reflected in IFs of 0.......1 or higher. Upon burial, the sediments lose porosity by mechanical compaction, and concurrently, the calcite particles recrystallize into progressively more equant shapes. High compaction rates may keep the particles in relative motion, whereas low compaction rates allow the formation of contact cement......, whereby IF increases and chalk forms. Rock mechanical tests show that when compaction requires more than in-situ stress, porosity reduction is arrested. During subsequent burial, crystals and pores grow in size as a consequence of the continuing recrystallization. ne lack of porosity loss during...

  15. Diagenesis and Evolution of the Holocene Coquinite from the Haishan Island,Eastern Guangdong,China

    SUN Jinlong; XU Huilong; QIU Xuelin; ZHAN Wenhuan; LI Yamin


    The coastal hard rock with a thickness of over 5 m and a distribution area of nearlv 200 ha in the Haishan Island.south China.has long drawn researchers'attention.However,there were controversies over its formation and classification.and these controversies iU turn lead to the dispute of sea level changes and coastal uplift-subsidence of this area.To investigate its diagenesis and evolution,petrographic analysis,elemental geochemistry,isotopic analysis,and radiocarbon dating were used in the present study.Radiocarbon dating indicates that the deposition of the Haishan Coquinite commenced in the mid Holocene and lasted to~600 a B.P. Petrographic analysis shows that the Haishan Coquinite is cemented by lOW-Mg calcite.indicating that the cementation occurred in a meteoric environment.The elemental geochemistry and isotopic values demonstrate that the coquinite SUfiered strong leaching,which was thought to be responsible for the meteoric cementation of the coquinite.According to these results,the diagenesis of the coquinite iS revealed:deposition of the Haishan Coquinite commenced in the mid Holocene in a shoal environment.initiaI cementation occurred and cement may be high-Mg calcite or aragonite;latterly the coquinite exposed to meteoric environment as a result of lowering of relative sea level,and the cement altered to IOW.Mg.which took the morphologies of bladed calcite rim and equant spar.A four-stage evolution model is proposed:(1) deposition stage,(2)initial cementation,(3)exposure to and cementation in meteoric environment. and(4)erosion stage.The published reports indicate that the hard rock should be designated as coquinite.Based on these studies.mid-Holocene sea level in this area was discussed.and the Haishan Island was proposed to uplift with a rate of~5mm/ainthelast~600 a.

  16. Early diagenesis of carbohydrates and lignin in mangrove sediments subject to variable redox conditions (French Guiana)

    Marchand, C.; Disnar, J. R.; Lallier-Vergès, E.; Lottier, N.


    A comparative study of lignin and neutral carbohydrate compositions, combined with C, N and δ 13C analyses, was carried out on sedimentary cores, and on various vascular plant species collected in mangrove swamps of French Guiana. The main purpose of this study was to assess the diagenesis of carbohydrates and lignin in brackish to hypersaline fine-grained mangrove sediments characterized by great changes in redox conditions. Distribution of carbohydrates in sediments reflects both the lability of these compounds and their efficient recycling. They are subject to selective degradation, cellulosic glucose and xylose appearing to be the two most labile neutral sugars. In contrast a relative increase in arabinose, rhamnose, fucose and hemicellulosic glucose between plants and sediments, suggests that they may be more refractory and/or that they also derive from microbial synthesis. The total carbon from lignin-derived phenols is higher in sediments than in mangrove plants as a consequence of their rather refractory character. Nevertheless, evidence of lignin decomposition was found to be independent of local environmental conditions. The various redox processes that occur in mangrove sediments depend on plant species, stages in forest development and season. Different redox conditions induce different mechanisms for the decomposition of lignin and thus induce changes in phenol distributions. At depth, in most mangroves, an increase in (Ad/Al) v ratios and in deoxy sugars (fucose and rhamnose) content was significantly correlated with increased proportions of oxidized allochthonous organic debris deriving from the Amazonian detrital discharge, thus suggesting a specific source effect rather than a diagenesis induced change. Therefore, this study illustrates that both lignin and cellulose, derived from vascular plant debris, can be degraded in waterlogged mangrove sediments, and that their distribution depends on environmental conditions.

  17. Diagenesis of Miocene, incised valley-filling limestones; Provence, Southern France

    Seibel, Margaret J.; James, Noel P.


    The Cenozoic of southeastern France is characterized by a series of incised valleys that were filled by a succession of marine carbonate and then siliciclastic sediments culminating in the modern Rhone River depositional system. The earliest of these paleovalleys (Miocene - Burdigalian) is located in the Pernes Hills between the towns of Saumane and Venasque. It was filled by a succession of marine carbonates in the form of two third-order stratigraphic sequences (S1 and S2) and three fourth-order subsequences (S1a, S1b and S1c). The deposits are heterozoan throughout, composed of echinoids, bryozoans, coralline algae, mollusks, and benthic foraminifers. They comprise a succession of spectacular cross-bedded calcarenites that accumulated in the seaward part of a tide-dominated estuary. Diagenesis is interpreted to have taken place in four stages: 1) minor synsedimentary precipitation of inclusion-rich carbonate cements, 2) shallow burial physical and chemical compaction, 3) subaerial exposure and widespread precipitation of clear, zoned, epitaxial and isopachous, followed by subsequent clear, unzoned, calcite cements and, 4) prolonged subaerial exposure (middle Miocene to Holocene), that involved dissolution, karstification, and precipitation of minor clear and locally pendant calcite cement. The rocks were essentially uncemented during shallow burial only to be well lithified during the early phases of subsequent telogenesis. The main controls on such lithification are interpreted to have been: 1) the dissolution of minor aragonite biofragments and precipitation of some LMC cement, 2) the abundance of echinoid particle nuclei for epitaxial cement nucleation, and 3) increasing rainfall together with regional tectonic uplift to the east that resulted in increased subsurface water flow. This study not only emphasizes the variable paragenesis of calcite-rich, heterozoan carbonates but also highlights the utility of these Cenozoic limestones with extant components as

  18. Mineralogy of Fluvio-Lacustrine Sediments Investigated by Curiosity During the Prime Mission: Implications for Diagenesis

    Rampe, Elizabeth B.; Morris, R. V.; Bish, D. L.; Vaniman, D. T.; Bristow, T. F.; Chipera, S. J.; Blake, D. F.; Ming, D. W.; Farmer, J. D.; Morrison, S. M.; Treiman, A. H.; Archilles, C. N.; Crisp, J. A.; DesMarais, D. J.; Downs, R. T.; Morookian, J. M.; Sarrazin, P.; Spanovich, N.; Yen, A. S.


    The Mars Science Laboratory rover Curiosity investigated sedimentary rocks that were deposited in a diversity of fluvio-lacustrine settings. The entire science payload was employed to characterize the mineralogy and chemistry of the Sheepbed mudstone at Yellowknife Bay and the Windjana sandstone at the Kimberley. Data from the CheMin instrument, a transmission Xray diffractometer, were used to determine the quantitative mineralogy of both samples. The Sheepbed mudstone contains detrital basaltic minerals, calcium sulfates, iron oxides or hydroxides, iron sulfides, trioctahedral smectite, and amorphous material. The mineral assemblage and chemical data from APXS suggest that the trioctahedral smectite and magnetite formed authigenically as a result of alteration of olivine. The apparent lack of higher-grade phyllosilicates (e.g., illite and chlorite) and the presence of anhydrite indicate diagenesis at 50- 80 ºC. The mineralogy of the Windjana sandstone is different than the Sheepbed mudstone. Windjana contains significant abundances of K-feldspar, low- and high-Ca pyroxenes, magnetite, phyllosilicates, and amorphous material. At least two distinct phyllosilicate phases exist: a 10 Å phase and a component that is expanded with a peak at 11.8 Å. The identity of the expanded phase is currently unknown, but could be a smectite with interlayer H2O, and the 10 Å phase could be illite or collapsed smectite. Further work is necessary to characterize the phyllosilicates, but the presence of illite could suggest that Windjana experienced burial diagenesis. Candidates for the cementing agents include fine-grained phyllosilicates, Fe-oxides, and/or amorphous material. Interpretations of CheMin data from the Windjana sandstone are ongoing at the time of writing, but we will present an estimate of the composition of the amorphous material from mass balance calculations using the APXS bulk chemistry and quantitative mineralogy from CheMin.

  19. Petroacoustic Modelling of Heterolithic Sandstone Reservoirs: A Novel Approach to Gassmann Modelling Incorporating Sedimentological Constraints and NMR Porosity data

    Matthews, S.; Lovell, M.; Davies, S. J.; Pritchard, T.; Sirju, C.; Abdelkarim, A.


    Heterolithic or 'shaly' sandstone reservoirs constitute a significant proportion of hydrocarbon resources. Petroacoustic models (a combination of petrophysics and rock physics) enhance the ability to extract reservoir properties from seismic data, providing a connection between seismic and fine-scale rock properties. By incorporating sedimentological observations these models can be better constrained and improved. Petroacoustic modelling is complicated by the unpredictable effects of clay minerals and clay-sized particles on geophysical properties. Such effects are responsible for erroneous results when models developed for "clean" reservoirs - such as Gassmann's equation (Gassmann, 1951) - are applied to heterolithic sandstone reservoirs. Gassmann's equation is arguably the most popular petroacoustic modelling technique in the hydrocarbon industry and is used to model elastic effects of changing reservoir fluid saturations. Successful implementation of Gassmann's equation requires well-constrained drained rock frame properties, which in heterolithic sandstones are heavily influenced by reservoir sedimentology, particularly clay distribution. The prevalent approach to categorising clay distribution is based on the Thomas - Stieber model (Thomas & Stieber, 1975), this approach is inconsistent with current understanding of 'shaly sand' sedimentology and omits properties such as sorting and grain size. The novel approach presented here demonstrates that characterising reservoir sedimentology constitutes an important modelling phase. As well as incorporating sedimentological constraints, this novel approach also aims to improve drained frame moduli estimates through more careful consideration of Gassmann's model assumptions and limitations. A key assumption of Gassmann's equation is a pore space in total communication with movable fluids. This assumption is often violated by conventional applications in heterolithic sandstone reservoirs where effective porosity, which

  20. Across the Gap: Geochronological and Sedimentological Analyses from the Late Pleistocene-Holocene Sequence of Goda Buticha, Southeastern Ethiopia

    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


    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

  1. Microbial-mat Sedimentology: A Young Branch fron Sedimentology%微生物席沉积学:一个年轻的沉积学分支



    现代实例和岩石记录的研究表明,微生物席是一个特别的微生物群落,这个特殊的微生物群落就像一个复杂的食物网一样,群落中的每一个组成成员紧密相互依赖,从而构成了地球上形成最早、延续时间最长的生态系.微生物席在沉积岩中留下了丰富而且复杂的记录,在碳酸盐岩中最为典型的产物就是叠层石,在碎屑岩中最具有代表性的产物就是"微生物诱发的沉积构造(MISS)".对这些特殊沉积记录的长期研究和探索,产生了沉积学在地球生物框架下的一个年轻分支--"微生物席沉积学";这个以微生物席为研究对象的年轻的沉积学分支,在研究地球早期生命演变、探索生物圈对水圈和大气圈的长时间影响,具有重要意义.若干的新概念和新思维,赋予这个年轻的沉积学分支强大的生命力,同时也代表了沉积学在近年来的一个重要进展之一.%Lots of studies on the microbial mat from the modern examples to the rock records show that the microbial mat is actually a complex microbial community. Just like a complex food web, microbial mats are communities of micro-organisms in which each member depends and is depended on by others in the community. Importantly, this special microbial community forms abundant and sophisticated records in sedimentary rocks. For these records , the stromatolite is the typical represent of microbial mats in carbonate rocks, and the MISS ( Microbial induced sedimentary structure) is the representative product that is related to microbial mats in siliclastic rocks. Long-term researches on these special records result in a young branch of sedimentology, I. E. " microbial-mat sedimentology" within the framework of geobiology, which plays a key role in the further studies of the evolution of the early life and in the further understanding of the evolutional rules of both the atmosphere and the hydrosphere in the earth. Lots of new concepts and

  2. Geophysical characterization of stratigraphical surfaces: Basin floor and sedimentological architectural elements of Las Tablas de Daimiel (Quaternary of southern-central Spain)

    Rey, Javier; Martínez, Julián; Mediavilla, Rosa; Santisteban, Juan I.; Castaño, Silvino; de la Losa, Almudena


    In this paper we analyse and compare the efficiency of electrical resistivity imaging (ERI) and ground-penetrating radar (GPR) as tools for stratigraphic and sedimentological studies. To this end, we carried out borehole drilling and geophysical survey campaigns in two locations in Las Tablas de Daimiel area (Ciudad Real, Spain). In this region, the Quaternary record is build up by siliciclastic deposits (gravel, sand and silt) of fluvial origin and organic matter-rich sediments (peat, clay and silty clay rich in organic matter) and carbonates (biogenic deposits mainly made up of Characeae) deposited in fluvial wetland environments that rest on Ordovician quartzites and Pliocene karstified carbonates. Electrical resistivity imaging (ERI) supported by surface and subsurface (boreholes) lithological information allow to identify the geometry of the basement-Quaternary boundary in two areas. The morphology of this boundary is controlled by fractures and the karstification of the top of the Pliocene limestones. Thirteen GPR profiles (100 and 250 MHz antenna) provide information about the morphology and internal structure of the sedimentary units, down to 4 m below the surface. The observed features include: onlap of the sediments on the edge of the basin, fossilization of small paleo-reliefs by lacustrine deposits and channel fills in the Holocene deposits, and the sinking-collapse structures in the Neogene substratum.

  3. Dark Matter

    Einasto, Jaan


    I give a review of the development of the concept of dark matter. The dark matter story passed through several stages from a minor observational puzzle to a major challenge for theory of elementary particles. Modern data suggest that dark matter is the dominant matter component in the Universe, and that it consists of some unknown non-baryonic particles. Dark matter is the dominant matter component in the Universe, thus properties of dark matter particles determine the structure of the cosmic...

  4. Sedimentological analyses of martian gullies: The subsurface as the key to the surface

    de Haas, Tjalling; Ventra, Dario; Hauber, Ernst; Conway, Susan J.; Kleinhans, Maarten G.


    Gullies are among the youngest landforms formed by liquid water on Mars, and therefore of critical importance in resolving the planets most recent hydrologic and climatic history. Water-free sediment flows, debris flows and fluvial flows have all been identified in gullies. These processes require very different amounts of liquid water, and therefore their relative contribution to gully-formation is of key importance for climatic inferences. We show that many gullies dominantly formed by debris flows, based on sedimentological analysis of outcrops in gully-fans in 51 HiRISE images widely distributed over the southern midlatitudes. The great majority (96%) of outcrop exposures in gully-fans fed by catchments which mainly comprise bedrock and thus host boulders, contain sedimentological evidence for debris-flow formation. These exposures contain many randomly distributed large boulders (>1 m) suspended in a finer matrix and in some cases lens-shaped and truncated layering. Such diagnostic features are rare in gully-fan exposures mainly fed by catchments comprising abundant latitude dependent mantle deposits (LDM; a smooth, often meters-thick deposit consisting mainly of ice and dust), wherein boulders are largely absent. These LDM-fed gullies may have formed by fine-grained debris flows, but this cannot be determined from outcrop sedimentology alone because of the lack of boulders in these systems. The fan surface morphology, in contrast to the subsurface, is dominated by secondary, post-depositional, processes, mainly weathering, wind erosion, and ice-dust mantling. These processes have removed or severely reworked the original, primary, debris-flow morphology over time. This explains the controversy between previously published morphometric analyses implying debris-flow formation and observations of gully-fan surfaces, which are often interpreted as the product of fluvial flows because of the absence of surficial debris-flow morphology. The inferred debris

  5. Petrofacies, provenance and diagenesis of the dhosa sandstone member (Chari Formation) at Ler, Kachchh sub-basin, Western India

    Ahmad, A. H. M.; Bhat, G. M.


    The sandstones of the Dhosa Sandstone Member of Late Callovian and Early Oxfordian age exposed at Ler have been analyzed for their petrofacies, provenance, tectonic setting and diagenetic history. These sandstones are fine to medium grained and poorly- to well sorted. The constituent mineral grains are subangular to subrounded. These sandstones were derived from a mixed provenance including granites, granite-gneisses, low- and high-grade metamorphic and some basic rocks of the Aravalli Range and Nagarparkar Massif. The petrofacies analysis reveals that these sandstones belong to the continental block-, recycled orogen- and rifted continental margin tectonic regime. The imprints of early and deep burial diagenesis of these sandstones include different stages of compaction, cementation, change in crystal boundaries, cement-cement boundaries, chertification and neomorphism. The sequence of cementation includes precipitation of calcite and its subsequent replacement by Fe calcite and silica cements. The typical intermediate burial (2-3 km depth) diagenetic signatures of these sandstones are reflected in the formation of suture and straight-line boundaries, and triple junctions with straight-line boundaries. The depositional environment, relatively low-energy environment that was below storm wave base but subjected to gentle currents, of the Dhosa Sandstone Member controlled the early diagenesis, which in turn influenced the burial diagenesis of these sandstones.

  6. Sedimentology and Ground-Penetrating Radar Characteristics of a Pleistocene Sandur Deposit

    Olsen, Henrik; Andreasen, Frank Erik


    -upward lithology, terminating with a jökulhlaup episode characterized by large compound dune migration and slack-water draping. Mapping of a more than 200 m long well exposed pitwall and ground-penetrating radar measurements in a 50 × 200 m grid along the pitwall made it possible to outline the three......-dimensional geometry of the jökulhlaup deposit, forming the top part of the succession. The paper describes the sedimentology of the sandur deposits and the application of the ground-penetrating radar technique to sedimentary architecture studies....

  7. Sedimentology and Ground-Penetrating Radar Characteristics of a Pleistocene Sandur Deposit

    Olsen, Henrik; Andreasen, Frank Erik


    -upward lithology, terminating with a jökulhlaup episode characterized by large compound dune migration and slack-water draping. Mapping of a more than 200 m long well exposed pitwall and ground-penetrating radar measurements in a 50 × 200 m grid along the pitwall made it possible to outline the three......-dimensional geometry of the jökulhlaup deposit, forming the top part of the succession. The paper describes the sedimentology of the sandur deposits and the application of the ground-penetrating radar technique to sedimentary architecture studies....

  8. Deltaic Morphology and Sedimentology, with Special Reference to the Indus River Delta.


    Shatt-al-Arab, and Chao submarine canyon restricts subaqueous delta Phraya (Fig. 10). The role of tides in the Indus development by funneling sediment...D -R I B S 1 9 8 D E L T I C M O R P H O L O G Y A N D S E D I E N T O L O G Y N I T H S P E C I LREFERENCE TO THE INDUS RIVER DELTA(U) LOUISIANA...424 DELTAIC MORPHOLOGY AND SEDIMENTOLOGY WITH SPECIAL REFERENCE TO THE INDUS RIVER DELTA J. T. Wells and J. M. Coleman 1985 Marine Geology

  9. Towards a quantitative climate reconstruction linking meteorological, limnological and sedimentological datasets: the Lake Sanabria (NW Spain) case.

    Rico-Herrero, María. Teresa; Giralt, Santiago; Valero-Garcés, Blas L.; Vega, José Carlos


    limnological towards the sediments. These relationships were studied using a statistical approach, such as ordination analyses (Principal Component and Redundancy Analyses), time series (auto- and cross-correlation funtions) and generalised linear models (glm). The precipitation and temperature oscillations account for more than 75% of the total variance of the Tera River discharge, and only precipitation explained more than the 55%. The lake reacts inmediately to changes in the precipitation as shown by best correlation between the three variables occurring at 0 lag-time. When exploring the possible relationships between meteorological and the limnological and nutrient datasets, it was evidenced that total phosphorous showed the best fit with 28% of the total explained variance. The best correlation was also observed at 0 lag, indicating that the main nutrient input occurs by the Tera River. Principal Component Analysis (PCA) on the XRF dataset showed that the first eigenvector explained more than 44% of the total variance and it was related mainly to the organic matter changes. Oscillations of this first eigenvector have been interpreted in terms of fluctuations of the primary productivity of Lake Sanabria. The comparison between the reconstructed primary productivity with the total phosphorous highlighted that lakes generally act as a low-pass filters, smoothing the climate signal when transfers it to the sediments. The explained variance between the smoothed reconstructed primary productivity and the total phosphorous is 24%, similar to that between the total phosphorous and the Tera River discharge. This study opens the possibility to a quantitative reconstruction of past climate data (temperature and precipitation) from high-resolution sedimentological datasets.

  10. Geochemistry and diagenesis of Miocene lacustrine siliceous sedimentary and pyroclastic rocks, Mytilinii basin, Samos Island, Greece

    Stamatakis, M.G.; Hein, J.R.; Magganas, A.C.


    A Late Miocene non-marine stratigraphic sequence composed of limestone, opal-CT-bearing limestone, porcelanite, marlstone, diatomaceous marlstone, dolomite, and tuffite crops out on eastern Samos Island. This lacustrine sequence is subdivided into the Hora Beds and the underlying Pythagorion Formation. The Hora Beds is overlain by the clastic Mytilinii series which contains Turolian (Late Miocene) mammalian fossils. The lacustrine sequence contains volcanic glass and the silica polymorphs opal-A, opal-CT, and quartz. Volcanic glass predominantly occurs in tuffaceous rocks from the lower and upper parts of the lacustrine sequence. Opal-A (diatom frustules) is confined to layers in the upper part of the Hora Beds. Beds rich in opal-CT underlie those containing opal-A. The occurrence of opal-CT is extensive, encompassing the lower Hora Beds and the sedimentary rocks and tuffs of the Pythagorion Formation. A transition zone between the opal-A and opal-CT zones is identified by X-ray diffraction patterns that are intermediate between those of opal-CT and opal-A, perhaps due to a mixture of the two polymorphs. Diagenesis was not advanced enough for opal-CT to transform to quartz or for volcanic glass to transform to opal-C. Based on geochemical and mineralogical data, we suggest that the rate of diagenetic transformation of opal-A to opal-CT was mainly controlled by the chemistry of pore fluids. Pore fluids were characterized by high salinity, moderately high alkalinity, and high magnesium ion activity. These pore fluid characteristics are indicated by the presence of evaporitic salts (halite, sylvite, niter), high boron content in biogenic silica, and by dolomite in both the opal-A and opal-CT-bearing beds. The absence of authigenic K-feldspar, borosilicates, and zeolites also support these pore fluid characteristics. Additional factors that influenced the rate of silica diagenesis were host rock lithology and the relatively high heat flow in the Aegean region from

  11. Early diagenesis and authigenic mineral formation in mobile muds of the Changjiang Estuary and adjacent shelf

    Zhao, Bin; Yao, Peng; Bianchi, Thomas S.; Xu, Yahong; Liu, Hui; Mi, Tiezhu; Zhang, Xiao-Hua; Liu, Jiwen; Yu, Zhigang


    Large-river delta-front estuaries (LDEs) and their adjacent shelf margins are sites of dynamic diagenetic processes that play a significant role in coastal biogeochemical cycling. In this study, we used dissolved inorganic carbon (DIC), redox sensitive elements (Fe2 + and Mn2 +), dissolved inorganic nitrogen (DIN) nutrients (NH4+, NO3-, and NO2-), major cations and anions (K+, Ca2 +, Mg2 +, SO42 -, and Cl-) in bottom-water and sediment pore-waters, to investigate the early chemical diagenesis and authigenic mineral formation in mobile-mud deposits of the Changjiang Estuary and adjacent inner shelf of the East China Sea (ECS). Vertical profiles of DIC and NH4+ in pore-waters had similar trends at most sites, showing a significant increase with depth near the Changjiang Estuary and being relatively constant at offshore sites. Higher pore-water DIC and NH4+ concentrations were observed in nearshore sites in winter, which were likely attributed to exposure of deeper deposits by winter coastal erosion. Nitrification was observed at most sites, and AOB (ammonia-oxidizing bacteria) played a leading role in ammonia oxidation in the study areas. The nitrification-denitrification was likely important in contributing to the loss of DIN in offshore sites during summer. Large inputs of organic carbon (OC) and terrestrial materials from Changjiang River resulted in intense sulfate reduction and Fe and Mn reduction in nearshore sites. Lower C/N and C/S ratios coupled with an apparent decrease in pore-water Ca2 + and Mg2+ concentrations with depth near the Changjiang Estuary, which indicated that authigenic carbonate formation occurs in these sediments. Decreases in K+ and Mg2 + with depth reflected that reverse weathering was an important process of authigenic mineral formation in these sediments. We conclude that adsorption process, seasonal erosion-redeposition, and summer hypoxic conditions of bottom-waters may play an important role in early diagenesis processes and

  12. Metal isotopes and carbonate proxy archives: Model-based perspectives on diagenesis

    Fantle, M. S.; Higgins, J. A.; Griffith, E. M.


    Metal isotopes are novel tools, and have expanded the geochemical toolbox for elucidating the functioning of the Earth over various time scales. Carbonate-based stable isotope proxies now extend well beyond the traditional major elements (C and O) to include Ca, as well as trace elements such as Sr, S, Mg, B, Li, Cd, and U. Such trace isotopic proxies may contain invaluable information about the Earth system in the past, but can be susceptible to diagenetic alteration over long time scales. It is therefore critical that diagenetic effects are understood and can be recognized in ancient rocks. The extent of alteration depends on reaction rate and advection velocity in the sedimentary section, and elemental partitioning and isotopic effects associated with diagenesis. Numerical approaches, such as reactive transport models, are extremely useful tools for constraining such variables, and for testing hypotheses related to alteration of proxy records. Reactive transport models allow for constraints on calcite recrystallization rates in natural systems; data from ODP Sites 807A, 1170A, 1171A, and 806B suggest rapid recrystallization in relatively young sediments, as well as a Ca isotopic fractionation factor (α) associated with calcite recrystallization close to 1 (Δ=0). While the former is critical for addressing the fidelity and accuracy of a variety of geochemical proxies, the latter is distinctly different from that associated with the formation of carbonates in the surface ocean (Δ~ -1.35‰), suggesting considerable isotopic leverage to alter Ca isotopes during diagenesis. While Ca isotopes are generally well buffered in carbonate-rich sediments, this leverage to alter may be expressed as a reduction in the amplitude of geochemical variability in the solid or as a result of reactions near the sediment-seawater interface (as seen at ODP Site 1221 associated with chemical burndown during the PETM). Further, the Ca and Mg isotopic compositions of shallow water

  13. Sedimentological Investigations of the Martian Surface using the Mars 2001 Robotic Arm Camera and MECA Optical Microscope

    Rice, J. W., Jr.; Smith, P. H.; Marshall, J. R.


    The first microscopic sedimentological studies of the Martian surface will commence with the landing of the Mars Polar Lander (MPL) December 3, 1999. The Robotic Arm Camera (RAC) has a resolution of 25 um/p which will permit detailed micromorphological analysis of surface and subsurface materials. The Robotic Ann will be able to dig up to 50 cm below the surface. The walls of the trench will also be inspected by RAC to look for evidence of stratigraphic and / or sedimentological relationships. The 2001 Mars Lander will build upon and expand the sedimentological research begun by the RAC on MPL. This will be accomplished by: (1) Macroscopic (dm to cm): Descent Imager, Pancam, RAC; (2) Microscopic (mm to um RAC, MECA Optical Microscope (Figure 2), AFM This paper will focus on investigations that can be conducted by the RAC and MECA Optical Microscope.


    Vanny Hertanto Vahyu


    Full Text Available The sedimentary rock is formed and associated with the diagenesis processes, as all the physical, chemical, andbiological changes in the characteristics of a sediment accumulation from the time the grains are deposited untilthey are metamorphosed. This process is profoundly influence the characteristic of sedimentary rock, including thetexture, internal structure, mineral composition, cementation type, and pore space. Hence, it is important to knowor learn the stage of sandstone diagenesis, especially in the Kerek Formation to mark the correlation betweendiagenesis and physical properties of sandstone.The purpose of this research is to identify the stage of diagenetic processes, diagenetic environment, the type ofcementation, and the relationship between diagenetic stage and physical properties of sandstone. The methods usedin this research are survey method and data analysis method. The survey method includes the making of crosssectionalmeasured stratigraphy and data analysis method includes petrographic and scanning electron microscopy(SEM.The sedimentary structures found in the carbonate sandstones are burrows, convolute ripple lamination, gradedbedding, parallel lamination, cross lamination, current ripple lamination; which are features of turbidity deposition(Bouma sequence. Based on the petrography analysis results for sample P 01 and P 02 showed compaction,cementation, dissolution, and bioturbation, with a porosity value of 1 %. Sample P 03 showed compaction,cementation, dissolution, and bioturbation, with a porosity value of 7 %. Sample P 04 showed compaction,cementation, and dissolution, with a porosity value of 1 %. Sample P 06 showed compaction, cementation,dissolution and replacement, with a porosity value of 5 %. Sample P 07 showed compaction, and cementation, witha porosity value of 30 %. The Lithology type in the research area was Calcarenite with dominant shell fragment,the lithology names are Packed biomicrite (Folks, 1959; in

  15. Overpressure generation by load transfer following shale framework weakening due to smectite diagenesis

    Lahann, R.W.; Swarbrick, R.E.


    Basin model studies which have addressed the importance of smectite conversion to illite as a source of overpressure in the Gulf of Mexico have principally relied on a single-shale compaction model and treated the smectite reaction as only a fluid-source term. Recent fluid pressure interpretation and shale petrology studies indicate that conversion of bound water to mobile water, dissolution of load-bearing grains, and increased preferred orientation change the compaction properties of the shale. This results in substantial changes in effective stress and fluid pressure. The resulting fluid pressure can be 1500-3000psi higher than pressures interpreted from models based on shallow compaction trends. Shale diagenesis changes the mineralogy, volume, and orientation of the load-bearing grains in the shale as well as the volume of bound water. This process creates a weaker (more compactable) grain framework. When these changes occur without fluid export from the shale, some of the stress is transferred from the grains onto the fluid. Observed relationships between shale density and calculated effective stress in Gulf of Mexico shelf wells confirm these changes in shale properties with depth. Further, the density-effective stress changes cannot be explained by fluid-expansion or fluid-source processes or by prediagenesis compaction, but are consistent with a dynamic diagenetic modification of the shale mineralogy, texture, and compaction properties during burial. These findings support the incorporation of diagenetic modification of compaction properties as part of the fluid pressure interpretation process. ?? 2011 Blackwell Publishing Ltd.

  16. Experimental diagenesis of organo-mineral structures formed by microaerophilic Fe(II)-oxidizing bacteria.

    Picard, Aude; Kappler, Andreas; Schmid, Gregor; Quaroni, Luca; Obst, Martin


    Twisted stalks are organo-mineral structures produced by some microaerophilic Fe(II)-oxidizing bacteria at O2 concentrations as low as 3 μM. The presence of these structures in rocks having experienced a diagenetic history could indicate microbial Fe(II)-oxidizing activity as well as localized abundance of oxygen at the time of sediment deposition. Here we use spectroscopy and analytical microscopy to evaluate if--and what kind of--transformations occur in twisted stalks through experimental diagenesis. Unique mineral textures appear on stalks as temperature and pressure conditions increase. Haematite and magnetite form from ferrihydrite at 170 °C-120 MPa. Yet the twisted morphology of the stalks, and the organic matrix, mainly composed of long-chain saturated aliphatic compounds, are preserved at 250 °C-140 MPa. Our results suggest that iron minerals might play a role in maintaining the structural and chemical integrity of stalks under diagenetic conditions and provide spectroscopic signatures for the search of ancient life in the rock record.

  17. Paleoclimate influence on early diagenesis of plant triterpenes in the Dajiuhu peatland, central China

    Huang, Xianyu; Xue, Jiantao; Wang, Xinxin; Meyers, Philip A.; Huang, Junhua; Xie, Shucheng


    Aromatic derivatives of vascular plant triterpenoids are common in recent and ancient sediments, coal, and petroleum. Understanding their early diagenetic alterations and their relation with environmental conditions can facilitate their applications in paleoenvironmental reconstructions. Here we present a high-resolution record of aromatic triterpenes in a Holocene peat core collected in the Dajiuhu peatland, central China. These aromatic triterpenes are derivatives of plant triterpenoids with oleanane, ursane and lupane carbon skeletons and exist in three different structural groups: aromatic des-A-triterpenes, aromatic pentacyclic triterpenes, and C-ring cleaved aromatic triterpenes. Such a high diversity of aromatic triterpenes in a young peat deposit is compelling evidence for rapid microbial mediation of these important degradation pathways during very early diagenesis. Of particular importance is the occurrence of C-ring cleaved aromatic triterpene and aromatic des-A-triterpenes in the Dajiuhu peat samples, which until now have not been identified in recent sediments. The downcore profile shows that the microbial aromatization process of oleanoids positively correlates with paleoclimate change. During dry or warm intervals, highly aromatized products such as tetraaromatic triterpenes become predominant over their triaromatic homologs. In contrast, triaromatic triterpenes become dominant during wet or cold intervals. In addition, this study provides further evidence to support that the climate pattern in the middle reaches of the Yangtze River is different from that in north China during 13-9.4 ka. These findings suggest that aromatic triterpenes can be valuable tools for Holocene paleoenvironmental reconstructions.

  18. Constraints on the formation and diagenesis of phosphorites using carbonate clumped isotopes

    Stolper, Daniel A.; Eiler, John M.


    The isotopic composition of apatites from sedimentary phosphorite deposits has been used previously to reconstruct ancient conditions on the surface of the Earth. However, questions remain as to whether these minerals retain their original isotopic composition or are modified during burial and lithification. To better understand how apatites in phosphorites form and are diagenetically modified, we present new isotopic measurements of δ18O values and clumped-isotope-based (Δ47) temperatures of carbonate groups in apatites from phosphorites from the past 265 million years. We compare these measurements to previously measured δ18O values of phosphate groups from the same apatites. These results indicate that the isotopic composition of many of the apatites do not record environmental conditions during formation but instead diagenetic conditions. To understand these results, we construct a model that describes the consequences of diagenetic modification of phosphorites as functions of the environmental conditions (i.e., temperature and δ18O values of the fluids) during initial precipitation and subsequent diagenesis. This model captures the basic features of the dataset and indicates that clumped-isotope-based temperatures provide additional quantitative constraints on both the formational environment of the apatites and subsequent diagenetic modification. Importantly, the combination of the model with the data indicates that the δ18O values and clumped-isotope temperatures recorded by phosphorites do not record either formation or diagenetic temperatures, but rather represent an integrated history that includes both the formation and diagenetic modification of the apatites.

  19. Geoarchaeology of Ancient Karnak's harbour (Upper Egypt) : preliminary results derived from sedimentological analyses

    Ghilardi, M.


    This paper aims to detail the first results of a geomorphological study, led in the western part of the Karnak Temple, Upper Egypt. The geoarchaeological approach privileged here helps to better understand the Nile River dynamics in the neighbourhood of the ancient harbour and of the jetty identified by archaeologists. Based on the study of six stratigraphical profiles, realized by the Egyptian Supreme Council of Antiquities and sixteen manual auger boreholes (up to a maximum depth of 3.50m) drilled in November 2008, the results clearly indicate the continuous presence of Nile River westward of the first Pylon. The boreholes were drilled westward and eastward of the ancient fluvial harbour. Fluvial dynamics characterized by flood events, sandy accretions and large Nile silts depositions are presented and discussed here for later palaeoenvironmental reconstruction. The accurate levelling of the different profiles and boreholes, with the help a topographic survey, allow us to get long sedimentological sequences and to correlate the different sedimentary units. Perspectives of research are introduced with the possibility to realize sedimentological analyses which include the grain-size distribution (sieving method employed) and a magnetic susceptibility study of the different sediments described. Finally, in order to obtain chronostratigraphic sequences, it is also proposed to perform radiocarbon dating on charcoal samples.

  20. Sedimentological, climatic and environmental changes during the Early Jurassic (Hettangian-Pliensbachian) on the northern Tethyan margin (Switzerland)

    Schöllhorn, Iris; Foellmi, Karl; adatte, Thierry


    The Early Jurassic interval witnessed different phases of paleoenvironmental change, starting with the end-Triassic mass extinction event, c. 201.4 Ma ago, which was marked by terrestrial ecosystem turnover, up to 50% loss in marine biodiversity and large turnovers in global geochemical cycles linked to the onset of Central Atlantic Magmatic Province volcanism (Raup et Sepkosky, 1982 ; Hesselbo et al., 2002 ; Deenen et al., 2010). This time interval saw equally a phase of major climate change near the Pliensbachian-Toarcian boundary, which was followed by the Early Toarcian oceanic anoxic episode (e.g., Suan et al., 2010). Previous studies mainly focused on these major and short-lived events, while the remaining intervals of the Early Jurassic received significantly less attention. Therefore, in this study, we examine the sedimentological, geochemical and environmental changes between these events on the northern Tethyan margin (Swiss Jura). With this purpose, a wide array of geochemical analyses (carbon isotope, Rock-Eval, phosphorus content, mineralogy, trace and major element content and clay analyses) and sedimentary observations has been performed on four sections and cores (Frick, Riniken, Pfaffnau and Kreuzlingen). We observed two depositional systems: (1) the Schambelen Member (lower Hettangian) and the Frick Mb. (middle Upper Sinemurian), which are characterised by organic-rich shales intercalated by tempestites; and (2) the Beggingen Member (Upper Hettangian to Lower Sinemurian) and the Grünscholz, Breitenmatt and Rietheim Members (upper Upper Sinemurian to Pliensbachian), which are composed of carbonates marked by the presence of hiati, condensed beds, phosphate- and fossil-rich strata, and erosional features, which testify to a dynamic environment characterised by overall low sediment-accumulation rates. The clay fraction, composed mainly of kaolinite, chlorite and illite, was controlled by various parameters. The rise of kaolinite in the Late

  1. Impact of diagenesis on the environmental magnetic record from a Holocene sedimentary sequence from the Chukchi-Alaskan margin, Arctic Ocean

    Brachfeld, Stefanie; Barletta, Francesco; St-Onge, Guillaume; Darby, Dennis; Ortiz, Joseph D.


    We present a high-resolution Holocene sedimentary record of environmental variability from the eastern Chukchi Sea. An ice-rafted debris bearing silty-clay marks the deglacial to post-glacial Holocene transition at this site and is dated at 9.7 ka. An interval of oscillating magnetic parameters from 9.5 to 8.7 ka coincides with the Holocene Thermal Maximum in the western Arctic, and is manifested at the study area as pulses of fine-grained magnetite input every 180-230 years, possibly from increased river discharge or stronger currents flowing over the core site. The magnetic mineral assemblage is very uniform over the last 8.2 ka and consists of a mixture of magnetite, titanomagnetite, and a magnetic phase that we tentatively identify as the magnetic iron sulfide greigite. The amount of magnetic iron sulfides increases up through the Holocene, a trend that is controlled by the amount of marine organic matter available to fuel bacterial sulfate reduction. The median destructive field of the Natural Remanent Magnetization (MDF NRM) displays centennial to millennial scale cycles with significant variance at periods of 900-1300 and 1700-2700 years, with intervals of high MDF NRM values coinciding with indicators of greater sea ice cover [McKay, J., de Vernal, A., Hillaire-Marcel, C., Not, C., Polyak, L., Darby, D., 2008. Holocene fluctuations in Arctic sea-ice cover: Dinocyst-based reconstructions for the eastern Chukchi Sea. Can. J. Earth Sci. 45, 1399-1415]. The MDF NRM is controlled by the variable abundance of iron sulfides formed during early diagenesis. We interpret intervals of high MDF NRM values as times of stronger water column stratification, during which the pyritization process was interrupted by the lack of marine organic matter and lack of reactive iron. Intervals of low MDF NRM values, which coincide with indicators of reduced sea ice cover, are interpreted as times of stronger vertical mixing of the water column, which allows fresh marine organic

  2. Implications of sedimentological and hydrological processes on the distribution of radionuclides in a salt marsh near Sellafield, Cumbria

    Carr, A.P.; Blackley, M.W.L.


    The report examines sedimentological and hydrological processes affecting a salt marsh in the Ravenglass estuary, which is situated south of the Sellafield nuclear-fuel-reprocessing plant. The results are discussed in the context of the distribution of low-level radioactive effluent at the site.

  3. Diagenesis of the lower Eocene Thebes Formation, Gebel Rewagen area, Eastern Desert, Egypt

    Shaaban, Mohamad N.


    The diagenesis of lower Eocene shallow water carbonates with flint was studied in the Gebel Rewagen area, Eastern Desert, Egypt. The carbonates are mainly wackestones to packstones with benthic bioclasts embedded in a dark red luminescent micrite matrix. The studied succession displays a complex diagenetic history that involves syngenetic and late diagenetic processes. Silica, which exists either as persistent bands, nodules and/or silicified benthic bioclasts shows a distinctive pattern regarding its distribution, source, depositional environments and timing. Three lines of evidence support a syngenetic origin of the chert bands: (1) they alternate in a cyclic manner within the host carbonates and (2) they exhibit noticeable lateral persistence throughout the investigated area following the strata boundaries and (3) there is a lack of any carbonate dissolution in limestone adjacent to chert bands. The deposition of silica bands in association with shallow water carbonates is possibly related to eustatic sea-level changes, which were accompanied by episodic variations in silica and carbonate productivities. With a relative sea-level fall and the establishment of a lowstand period at the end of the early Eocene, a basinward shift of the groundwater zones is expected within the carbonate platform. During this period some late diagenetic processes took place, which involve: (1) the formation of siliceous and carbonate concretionary growths, (2) partial silicification of bioclasts, (3) neomorphic stabilization of the CaCO 3 bioclasts and (4) the formation of equant calcite cement. Siliceous and carbonate concretions are believed to have taken place within microenvironments created and controlled by sulphate-reducing bacteria and physico-chemical and kinetic factors near a marine-meteoric water mixing zone. This is inferred from the distribution of iron sulphides, the non-ferroan nature of all concretions and the depleted δ13C (-5.4‰ to -6.0‰ PDB) and δ18O (-5.8

  4. Raman spectral, elemental, crystallinity, and oxygen-isotope variations in conodont apatite during diagenesis

    Zhang, Lei; Cao, Ling; Zhao, Laishi; Algeo, Thomas J.; Chen, Zhong-Qiang; Li, Zhihong; Lv, Zhengyi; Wang, Xiangdong


    Conodont apatite has long been used in paleoenvironmental studies, often with minimal evaluation of the influence of diagenesis on measured elemental and isotopic signals. In this study, we evaluate diagenetic influences on conodonts using an integrated set of analytical techniques. A total of 92 points in 19 coniform conodonts from Ordovician marine units of South China were analyzed by micro-laser Raman spectroscopy (M-LRS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), high-resolution X-ray microdiffraction (HXRD), and secondary ion mass spectrometry (SIMS). Each conodont element was analyzed along its full length, including the albid crown, hyaline crown, and basal body, in either a whole specimen (i.e., reflecting the composition of its outer layer) or a split specimen (i.e., reflecting the composition of its interior). In the conodonts of this study, the outer surfaces consist of hydroxyfluorapatite and the interiors of strontian hydroxyfluorapatite. Ionic substitutions resulted in characteristic Raman spectral shifts in the position (SS1) and width (SS2) of the ν1-PO43- stretching band. Although multiple elements were enriched (Sr2+, Mg2+) and depleted (Fe3+, Mn2+, Ca2+) during diagenesis, geochemical modeling constraints and known Raman spectral patterns suggest that Sr uptake was the dominant influence on diagenetic redshifts of SS1. All study specimens show lower SS2 values than modern bioapatite and synthetic apatite, suggesting that band width decreases with time in ancient bioapatite, possibly through an annealing process that produces larger, more uniform crystal domains. Most specimens consist mainly of amorphous or poorly crystalline apatite, which is inferred to represent the original microstructure of conodonts. In a subset of specimens, some tissues (especially albid crown) exhibit an increased degree of crystallinity developed through aggrading neomorphism. However, no systematic relationship was observed between

  5. Dark matter

    Einasto, J.


    I give a review of the development of the concept of dark matter. The dark matter story passed through several stages from a minor observational puzzle to a major challenge for theory of elementary particles. Modern data suggest that dark matter is the dominant matter component in the Universe, and that it consists of some unknown non-baryonic particles. Properties of dark matter particles determine the structure of the cosmic web.

  6. Microbial Precipitation and Diagenesis in Salt Ponds from Little Darby Island, Exumas, Bahamas.

    Piggot, A. M.; Klaus, J.; Swart, P. K.; Reid, P.


    Microbial activity is responsible for the majority of carbonate precipitation and early diagenesis in restricted hypersaline ponds on Little Darby Island, Bahamas. The four ponds on Little Darby exhibit a range of salinities (10-69) and sedimentary deposits that record the evolution of ponds from restricted shallow marine embayments to isolated hypersaline ponds. Only the largest and most hypersaline pond, Anaconda, was covered by a classically defined multi-layered microbial mat (3 cm thick) with calcium carbonate precipitates. Microbial laminations and organosedimentary layers were preserved throughout the 90cm sediment core. The brackish ponds had thinner (Actinobacteria, Alphaproteobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Deltaproteobacteria, Gammaproteobacteria and Planctomycetes, with metabolisms previously linked to carbonate producing mat systems. Sulfate reduction and heterotrophic degradation of exopolymeric substances were identified as the primary mechanism for microbial carbonate precipitation. The δ13C values of carbonate sediments ranged from -5.5‰ to 3‰, with the more negative values representing the heterotrophic involvement in carbonate precipitation. The more positive values (0-3‰) were associated with the deeper sediments deposited in a marine environment before the ponds were isolated. Pore fluid chemical ratios of Ca2+/Cl-, Mg2+/Cl-, and Sr2+/Cl- ratios also suggest that precipitation and recrystallization of carbonate minerals is occurring in the buried sediments and indicates that the microbial influence on buried sediments is not limited to surface mats. The results reported here demonstrate that the absence of microbially induced sedimentary structures, such as laminations in hypersaline ponds, does not imply the absence of microbially mediated carbonate precipitation.

  7. Behaviour of sulphur during diagenesis of a maritime ombrotrophic peat from Yell, Shetland Islands, UK

    Bartlett, Rebecca [Department of Earth Sciences, School of Earth and Environment, University of Leeds, LEEDS LS2 9JT (United Kingdom); Bottrell, Simon [Department of Earth Sciences, School of Earth and Environment, University of Leeds, LEEDS LS2 9JT (United Kingdom)]. E-mail:; Coulson, Jonathan [Department of Earth Sciences, School of Earth and Environment, University of Leeds, LEEDS LS2 9JT (United Kingdom); Department of Animal and Plant Sciences, University of Sheffield, SHEFFIELD S10 2TN (United Kingdom)


    Surface water, pore water, vegetation and peat cores were sampled from a waterlogged ombrotrophic peat bog on the Shetland Isles, UK and analysed for different S forms and their isotopic composition, in an attempt to elucidate the biogeochemical processes affecting S during peat diagenesis. Surface waters show that inputs of S to the peat have a maritime-dominated isotopic composition close to +20%%{sub CDT}. Uptake of S by vegetation introduces a -10%% shift in {delta}{sup 34}S from these input values. Below the vegetation layer and down to 18cm depth, bacterial SO{sub 4}{sup 2-} reduction is the major control on S species distribution and isotopic composition within the solid peat and pore waters. In this part of the peat, preferential reduction of {sup 32}SO{sub 4} in pore water during metabolism produces isotopically light sulphide, which is incorporated into the solid phase in both inorganic and organic forms, while pore water SO{sub 4}{sup 2-} becomes enriched in {sup 34}S. From 18 to 28cm, organic S content falls relative to C and residual organic S becomes {sup 34}S-enriched, indicative of mineralization of organic S, a process which releases isotopically light S to the pore waters. Still deeper in the core (28 to {approx}50cm), bacterial reduction of pore-water SO{sub 4}{sup 2-}, now enriched in {sup 34}S, results in addition of isotopically heavy S to the solid phase. Limited pore water data suggest that below 50cm mineralization reactions again release S from the organic fraction of the peat.

  8. Sedimentological study of a lagoon through natural radioactivity and 137Cs determinations

    San Miguel, E. G.; Pérez-Moreno, J. P.; Aguado, J. L.; Bolívar, J. P.; García-Tenorio, R.


    Profiles of artificial fallout (such as 137Cs) and natural radioactivity radionuclides in sediment cores are useful tools to study sedimentological properties of different aquatic environments as well as to evaluate average sedimentation rates. In the Portil lagoon, a small natural reservoir located in Huelva province (southwest of Spain), and through the analysis of 210Pb, 226Ra, 137Cs, 238U and 210Po vertical profiles in sediment cores, it is shown how the accumulative or transport character of the collection zones may be inferred. In the accumulation zone of the lagoon the influence of focusing effects has been analysed and an average sedimentation rate has been determined through 210Pb in one sediment core. This 210Pb-sedimentation rate is consistent with sediment dating based on the 137Cs data.

  9. Soil sedimentology at Gusev Crater from Columbia Memorial Station to Winter Haven

    Cabrol, N.A.; Herkenhoff, K. E.; Greeley, R.; Grin, E.A.; Schroder, C.; d'Uston, C.; Weitz, C.; Yingst, R.A.; Cohen, B. A.; Moore, J.; Knudson, A.; Franklin, B.; Anderson, R.C.; Li, R.


    A total of 3140 individual particles were examined in 31 soils along Spirit's traverse. Their size, shape, and texture were quantified and classified. They represent a unique record of 3 years of sedimentologic exploration from landing to sol 1085 covering the Plains Unit to Winter Haven where Spirit spent the Martian winter of 2006. Samples in the Plains Unit and Columbia Hills appear as reflecting contrasting textural domains. One is heterogeneous, with a continuum of angular-to-round particles of fine sand to pebble sizes that are generally dust covered and locally cemented in place. The second shows the effect of a dominant and ongoing dynamic aeolian process that redistributes a uniform population of medium-size sand. The texture of particles observed in the samples at Gusev Crater results from volcanic, aeolian, impact, and water-related processes. Copyright 2008 by the American Geophysical Union.

  10. Sedimentology models from activity concentration measurements: application to the "Bay of Cadiz" Natural Park (SW Spain).

    Ligero, R A; Vidal, J; Meléndez, M J; Hamani, M; Casas-Ruiz, M


    A previous study on seabed sediments of the Bay of Cadiz (SW of Spain) enabled us to identify several relations between sedimentological variables and activity concentrations of environmental radionuclides such as (137)Cs, (226)Ra, (232)Th and (40)K. In this paper the study has been extended to a large neighbouring inter-tidal area in order to establish if the above mentioned models can be generalized. As a result we have determined that the measured activity concentrations are closely to the values predicted by the theoretical models (correlation coefficient range=0.85-0.93). Furthermore, the proposal model for granulometric facies as a function of activity concentrations of the abovementioned radionuclides provides for the sediments distribution a representation which agrees with the values of the tidal energy distribution obtained using numeric models calibrated with experimental data from current meters and water level recorders.

  11. Stratigraphy and sedimentology of the K/T boundary deposit in Haiti

    Carey, S.; Sigurdsson, H.; Dhondt, S.; Espindola, J. M.


    The K/T boundary sequence is exposed in uplifted carbonate sediments of the southwest peninsula of Haiti. It is found at 15 localities within the Beloc formation, a sequence of limestone and marls interpreted as a monoclinal nappe structure thrust to the north. This tectonic deformation has affected the K/T boundary deposit to varying degrees. In some cases the less competent K/T deposit has acted as a slip plane leading to extensive shearing of the boundary layer, as well as duplication of the section. The presence of glassy tektites, shocked quartz, and an Ir anomaly directly link the deposit to a bolide impact. Stratigraphic and sedimentological features of the tripartite sequence indicate that it was formed by deposition from ballistic fallout of coarse tektites, emplacement of particle gravity flows and fine grained fallout of widely dispersed impact ejecta.

  12. Sedimentology of gas-bearing Devonian shales of the Appalachian Basin

    Potter, P.E.; Maynard, J.B.; Pryor, W.A.


    The Eastern Gas Shales Project (1976-1981) of the US DOE has generated a large amount of information on Devonian shale, especially in the western and central parts of the Appalachian Basin (Morgantown Energy Technology Center, 1980). This report summarizes this information, emphasizing the sedimentology of the shales and how it is related to gas, oil, and uranium. This information is reported in a series of statements each followed by a brief summary of supporting evidence or discussion and, where interpretations differ from our own, we include them. We believe this format is the most efficient way to learn about the gas-bearing Devonian shales of the Appalachian Basin and have organized our statements as follows: paleogeography and basin analysis; lithology and internal stratigraphy; paleontology; mineralogy, petrology, and chemistry; and gas, oil, and uranium.

  13. Morphology and sedimentology of the Itaipú Embayment - Niterói/RJ



    Full Text Available Bathymetric and sedimentological data from water depths between 3 and 28 meters are the basis of a detailed bathymetric map of the Itaipú Embayment and an understanding of its sedimentary dynamics. Shallower than 16 meters the contours are parallel to the shoreline whereas the morphology of the deeper bottom is influenced by the Menina, Mãe, and Pai islands. Medium sand is prevalent, with local variations in more protected or less protected areas. Minor amount of black mud possibly derives from the Itaipú Lagoon. Siliciclastic granules and pebbles may be relict. The Itaipú Embayment's bottom morphology is controlled by stormy waves and the calmer easternmost part of the embayment presents a tendency to accumulate finer sediments.

  14. Thermodynamic simulation of the interaction of the system “water - mineral sediment - organic matter” at the diagenesis stage

    Sidkina, E. S.; Rizhenko, B. N.; Cherkasova, E. V.


    The current study examines thermodynamic calculations of interaction of the “water - mineral sediment - organic matter” system at temperatures and pressures of diagenesis. In the course of reactions mature kerogen forms in the system, mainly C292H288O12, rarely C128H68O7 including accompanying substances (hydrocarbons, nitrogen compounds). The removal of CO2(g) and N2 (g) from the system promotes the reaction. It is found that the aqueous phase during the formation of kerogen does not change significantly. In general, there occur desalination and changes of pH and Eh, as well as the increase in dissolved CO2 content in water composition.

  15. Sedimentology and ichnology of Neogene Coastal Swamp deposits in the Niger Delta Basin, Nigeria

    Ezeh, Sunny C.; Mode, Wilfred A.; Ozumba, Berti M.; Yelwa, Nura A.


    Often analyses of depositional environments from sparse data result in poor interpretation, especially in multipartite depositional settings such as the Niger Delta. For instance, differentiating channel sandstones, heteroliths and mudstones within proximal environments from those of distal facies is difficult if interpretations rely solely on well log signatures. Therefore, in order to achieve an effective and efficient interpretation of the depositional conditions of a given unit, integrated tools must be applied such as matching core descriptions with wireline log signature. In the present paper cores of three wells from the Coastal Swamp depositional belt of the Niger Delta are examined in order to achieve full understanding of the depositional environments. The well sections comprise cross-bedded sandstones, heteroliths (coastal and lower shoreface) and mudstones that were laid down in wave, river and tidal processes. Interpretations were made from each data set comprising gamma ray logs, described sedimentological cores showing sedimentary features and ichnological characteristics; these were integrated to define the depositional settings. Some portions from one of the well sections reveal a blocky gamma ray well log signature instead of a coarsening-upward trend that characterises a shoreface setting while in other wells the signatures for heteroliths at some sections are bell blocky in shaped rather than serrated. Besides, heteroliths and mudstones within the proximal facies and those of distal facies were difficult to distinguish solely on well log signatures. However, interpretation based on sedimentology and ichnology of cores from these facies was used to correct these inconsistencies. It follows that depositional environment interpretation (especially in multifarious depositional environments such as the Niger Delta) should ideally be made together with other raw data for accuracy and those based solely on well log signatures should be treated with

  16. Sedimentological reservoir characteristics of the Paleocene fluvial/lacustrine Yabus Sandstone, Melut Basin, Sudan

    Mahgoub, M. I.; Padmanabhan, E.; Abdullatif, O. M.


    Melut Basin in Sudan is regionally linked to the Mesozoic-Cenozoic Central and Western African Rift System (CWARS). The Paleocene Yabus Formation is the main oil producing reservoir in the basin. It is dominated by channel sandstone and shales deposited in fluvial/lacustrine environment during the third phase of rifting in the basin. Different scales of sedimentological heterogeneities influenced reservoir quality and architecture. The cores and well logs analyses revealed seven lithofacies representing fluvial, deltaic and lacustrine depositional environments. The sandstone is medium to coarse-grained, poorly to moderately-sorted and sub-angular to sub-rounded, arkosic-subarkosic to sublitharenite. On the basin scale, the Yabus Formation showed variation in sandstone bodies, thickness, geometry and architecture. On macro-scale, reservoir quality varies vertically and laterally within Yabus Sandstone where it shows progressive fining upward tendencies with different degrees of connectivity. The lower part of the reservoir showed well-connected and amalgamated sandstone bodies, the middle to the upper parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenetic changes such as compaction, cementation, alteration, dissolution and kaolinite clays pore fill and coat all have significantly reduced the reservoir porosity and permeability. The estimated porosity in Yabus Formation ranges from 2 to 20% with an average of 12%; while permeability varies from 200 to 500 mD and up to 1 Darcy. The understanding of different scales of sedimentological reservoir heterogeneities might contribute to better reservoir quality prediction, architecture, consequently enhancing development and productivity.

  17. Initial India-Asia Collision: Sedimentologic, Paleomagnetic and Paleontologic Evidence From the Ghazij Formation, Balochistan, Pakistan

    Clyde, W. C.; Khan, I. H.; Gingerich, P. D.


    Initial continental collision between India and Asia is thought to have caused significant changes to global climate and biota, yet its timing and biogeographic consequences are uncertain. Structural and geophysical evidence indicates initial collision during the early Paleogene, but sedimentary evidence of this has been controversial owing to the intense deformation and metamorphism along the suture zone. Modern orders of mammals that appeared abruptly on northern continents coincident with the global warming event marking the Paleocene-Eocene boundary are hypothesized to have originated on the Indian subcontinent, but no relevant paleontologic information has been available to test this idea. Here we present sedimentologic, paleomagnetic, and paleontologic results that show the lower Eocene Ghazij Formation of western Pakistan records continental sedimentation and mammalian dispersal associated with initial India-Asia collision. Sedimentologically, the Ghazij exhibits a clear transition from shallow-marine facies in the lower part, to paralic deltaic facies in the middle part, and continental fluvial facies in the upper part. Paleomagnetic data indicate that Ghazij deposition occurred just before a pronounced decrease in the sea-floor spreading rate of the Indian Ocean. Large fossil mammal assemblages show strong endemism in the middle part of the formation but increasing cosmopolitanism and affiliation with northern continents higher in the formation. Our results support the hypothesis that initial continent-continent contact occurred near the Paleocene-Eocene boundary along the northwest edge of the Indo-Pakistan plate and that subsequent closure occurred diachronously along the rest of the suture. However, it appears that during initial collision, modern orders of mammals dispersed into India rather than out of it.

  18. Sedimentology and ichnology of Neogene Coastal Swamp deposits in the Niger Delta Basin, Nigeria

    Ezeh Sunny C.


    Full Text Available Often analyses of depositional environments from sparse data result in poor interpretation, especially in multipartite depositional settings such as the Niger Delta. For instance, differentiating channel sandstones, heteroliths and mudstones within proximal environments from those of distal facies is difficult if interpretations rely solely on well log signatures. Therefore, in order to achieve an effective and efficient interpretation of the depositional conditions of a given unit, integrated tools must be applied such as matching core descriptions with wireline log signature. In the present paper cores of three wells from the Coastal Swamp depositional belt of the Niger Delta are examined in order to achieve full understanding of the depositional environments. The well sections comprise cross-bedded sandstones, heteroliths (coastal and lower shoreface and mudstones that were laid down in wave, river and tidal processes. Interpretations were made from each data set comprising gamma ray logs, described sedimentological cores showing sedimentary features and ichnological characteristics; these were integrated to define the depositional settings. Some portions from one of the well sections reveal a blocky gamma ray well log signature instead of a coarsening-upward trend that characterises a shoreface setting while in other wells the signatures for heteroliths at some sections are bell blocky in shaped rather than serrated. Besides, heteroliths and mudstones within the proximal facies and those of distal facies were difficult to distinguish solely on well log signatures. However, interpretation based on sedimentology and ichnology of cores from these facies was used to correct these inconsistencies. It follows that depositional environment interpretation (especially in multifarious depositional environments such as the Niger Delta should ideally be made together with other raw data for accuracy and those based solely on well log signatures should

  19. New sedimentological and palynological data from surface Miocene strata in the central Amazonas Basin area

    Emílio Alberto Amaral Soares

    Full Text Available ABSTRACT The scarcity of stratigraphic data has hindered the demarcation of the outcropping area of Miocene deposits of the Amazon Basin, represented informally by the Novo Remanso Formation. Moreover, this unit is characterized by a sparse and irregular geographic distribution due to its sedimentological features and rare fossil content. Miocene deposits cropping out in central Amazonas Basin area were described in sedimentological terms and analyzed palynologically. All analyses were undertaken in samples collected at the Uatumã River banks (Itapiranga and São Sebastião do Uatumã cities. Lithostratigraphic data shows that Novo Remanso Formation consists of sandstones, with subordinate conglomerates and pelites, characteristic of a meandering fluvial paleosystem, with fluvial channel, point bar, floodplain and crevasse splay facies. The palynoflora retrieved from five samples consists exclusively of continental-origin palynomorphs dominated by angiosperms species. Trilete spores are well represented, while gymnosperms pollen grains are minor components. The presence of Psilastephanoporites tesseroporus, Syncolporites poricostatus, Jandufouria seamrogiformis and Polypodiaceoisporites potoniei ensure these deposits fits into the Grimsdalea magnaclavata palynozone (Regali et al. 1974a, b, and the Grimsdalea magnaclavata/Crassoretitriletes vanraadshooveni palynozones of Jaramillo et al. (2011 considered Middle Miocene age. This age is confirmed by the zonation of Jaramillo et al. (2011, based on the LADs of Bombacacidites baumfalki (11.57Ma and Crototricolpites annemariae (12.91Ma; and the FAD of Psilastephanoporites tesseroporus (14.00Ma. With these new data presented herein, it is possible to assume that the Miocene strata represented by the Novo Remanso Formation covers a larger area in the basin than previously considered, and that it may be extended for about 300 km until the Manacapuru village, indicating a Miocene subsidence phase.

  20. Biotic and Sedimentologic Signals Associated with Tempestite Deposition from Baffin Bay, Texas

    Van Nieuwenhuise, D. S.


    In efforts to determine hurricane frequency prior to historical records, the often used model of counting presumed washover fans as coarse-grained hurricane deposits that interfinger with fine-grained, quiet, lagoon sediments may be oversimplified. The complexities of hurricane depositional events versus the usual dynamic sedimentological processes of barrier island complexes often makes it difficult to distinguish between expected and typical migrating coarse-grained facies from true hurricane deposits. To avoid some of this potential confusion and to better recognize the frequency of strong hurricane events, it is suggested that studies be focused further inland than the washover fans and that in addition to sedimentological indicators, they include biotic and chemical discriminators as well. These results are part of a broader study examining hurricane deposition along the Texas coast. The focus of this study is on slowly accumulating algal mats near Baffin Bay, Texas, that are punctuated by known hurricane deposits. This marginal lagoonal setting is more than 16 miles away from the Padre Island shorefront. Two cores were taken in 1974 that captured sediments from Hurricane Carla (1970) and Hurricane Beulah (1967). Algal mat depositional rates are on the order of 1.25 cm per year whereas the hurricane sediments are on the order of 45 cm per event. Sediments display flood and ebb surge stages for each event. Additional cores in other parts of the coast have similar sediment accumulation rates. In general, periods of relatively quiet deposition are dominated by Cyprideis ovata and Ammonia becarrii which can tolerate the conditions of these euryhaline and algal-floored ponds. In contrast, hurricane deposits show clear evidence of additional bay and shallow marine assemblages along with coarse-grained sediments, shell and shell fragments, and significant amounts of mud settling after the retreat of the storm surge.

  1. Investigation of Sediment Pathways and Concealed Sedimentological Features in Hidden River Cave, Kentucky

    Feist, S.; Maclachlan, J. C.; Reinhardt, E. G.; McNeill-Jewer, C.; Eyles, C.


    Hidden River Cave is part of a cave system hydrogeologically related to Mammoth Cave in Kentucky and is a multi-level active cave system with 25km of mapped passages. Upper levels experience flow during flood events and lower levels have continuously flowing water. Improper industrial and domestic waste disposal and poor understanding of local hydrogeology lead to contamination of Hidden River Cave in the early 1940s. Previously used for hydroelectric power generation and as a source of potable water the cave was closed to the public for almost 50 years. A new sewage treatment plant and remediation efforts since 1989 have improved the cave system's health. This project focuses on sedimentological studies in the Hidden River Cave system. Water and sediment transport in the cave are being investigated using sediment cores, surface sediment samples and water level data. An Itrax core scanner is used to analyze sediment cores for elemental concentrations, magnetic susceptibility, radiography, and high resolution photography. Horizons of metal concentrations in the core allow correlation of sedimentation events in the cave system. Thecamoebian (testate amoebae) microfossils identified in surface samples allow for further constraint of sediment sources, sedimentation rates, and paleoclimatic analysis. Dive recorders monitor water levels, providing data to further understand the movement of sediment through the cave system. A general time constraint on the sediment's age is based on the presence of microplastic in the surface samples and sediment cores, and data from radiocarbon and lead-210 dating. The integration of various sedimentological data allows for better understanding of sedimentation processes and their record of paleoenvironmental change in the cave system. Sediment studies and methodologies from this project can be applied to other karst systems, and have important applications for communities living on karst landscapes and their water management policies.

  2. Current hot topics and advances of sedimentology:A summary from 32nd IAS Meeting of Sedimentology%沉积学研究热点与进展:第32届国际沉积学会议综述

    朱筱敏; 董艳蕾; 李顺利; 潘荣; 谈明轩; 陈贺贺; 王星星; 陈锋; 张梦瑜; 侯冰洁


    第32届国际沉积学会议(32nd IAS Meeting of Sedimentology)于2016年5月23—25日在摩洛哥马拉喀什召开,来自43个国家和地区的360余名学者参加了本次会议。综述研究表明,会议研究热点为陆相沉积环境、浅水沉积与滨岸潮汐、深水沉积与事件沉积、碳酸盐与化学岩沉积、沉积过程与盆地分析、成岩作用与油气储集层等研究领域。会议主要研究进展表现为:波浪再悬浮作用(wave resuspension)与异重流(hyperpyc-nal flows)是陆架边缘斜坡快速进积的主要因素;海啸发生周期为14~35ka,后积层理(backset-bedding)为海啸沉积识别标志;海底滑坡多由海底地震、天然气水合物泄露等触发,其块状搬运沉积物(MTD )包括滑塌头部、滑动底面、滑塌主体以及滑塌后期浊流沉积;玄武岩等基岩的风化作用提供硅与富镁碱性水,有利于菱沸石与白云石的形成;受构造作用影响,隆起剥蚀区与沉积区可互为转化;物源性质、供给量及搬运或分散过程控制了沉积面貌(源汇系统);构造活动直接控制可容纳空间变化、地貌变化、源区剥蚀速率、沉积物供应速率等。最后,本文对比了中外沉积学发展差异,讨论了中国沉积学发展方向。%The 32nd IAS Meeting of Sedimentology was held in Marrakech, Morocco, from 23 to 25May 201 6.More than 360 sedimentologists from 43 countries and regions participated in this meeting.A review of research indicates that hot issues of this meeting mainly consist of continental sedimentary envi-ronment,shallow water deposits and coastal tidal systems,deep water sedimentation and event sedimenta-tion,carbonate and chemical deposition,sedimentary process and basin analysis,diagenesis and hydro-carbon reservoirs.Main progresses of the meeting are listed as follows.Wave resuspension and hyperpycnal flow contribute to rapid progradation of shelf

  3. Solid Matter

    Angelo, Joseph A


    Supported by a generous quantity of full-color illustrations and interesting sidebars, Solid Matter introduces the basic characteristics and properties of solid matter. It briefly describes the cosmic connection of the elements, leading readers through several key events in human pre-history that resulted in more advanced uses of matter in the solid state. Chapters include:. -Solid Matter: An Initial Perspective. -Physical Behavior of Matter. -The Gravity of Matter. -Fundamentals of Materials Science. -Rocks and Minerals. -Metals. -Building Materials. -Carbon Earth's Most Versatile Element. -S

  4. The fate of terrestrial organic matter in two Scottish sea lochs

    Loh, P. S.; Reeves, A. D.; Harvey, S. M.; Overnell, J.; Miller, A. E. J.


    Sea lochs are zones of rapid organic matter (OM) turnover. Most of this OM is of allochthonous origin, being introduced into the lochs via freshwater input. In this study the behaviour of terrestrially derived OM was elucidated using a combination of parameters which indicate OM diagenesis in the near surface sediments from two Scottish sea lochs, Loch Creran and Loch Etive. Alkaline CuO oxidation was used to determine lignin phenols which serve as biomarkers for terrestrial OM in sediments. Stable carbon isotope, total carbon and nitrogen and total OM (including the labile and refractory fractions) compositions were also determined. Lignin materials in the lochs were generally highly degraded and undergo little degradation further seaward. The vanillic acid to vanillin ratio, (Ad/Al)v in the lochs ranged from 0.52 to 2.69. However, there was a fraction of relatively fresh, land-derived OM, still undergoing degradation adding to the carbon cycling in the lochs, as indicated by the Rp values (ratio of refractory to total OM) and OC/N ratios in the surface sediments. The hydrological and hydrodynamic regimes in Loch Creran result in several phenomena such as the transportation of terrestrial debris via hydrodynamic sorting processes and the promotion of surface sediment diagenesis by bioturbation. Frequent water renewal results in better water circulation and oxygenation which facilitate OM decomposition. In Loch Etive the less frequent renewal gives rise to a more constant OM diagenesis along the loch.

  5. Speech Matters

    Hasse Jørgensen, Stina


    About Speech Matters - Katarina Gregos, the Greek curator's exhibition at the Danish Pavillion, the Venice Biannual 2011.......About Speech Matters - Katarina Gregos, the Greek curator's exhibition at the Danish Pavillion, the Venice Biannual 2011....

  6. Memory Matters

    ... Emergency Room? What Happens in the Operating Room? Memory Matters KidsHealth > For Kids > Memory Matters A A ... of your complex and multitalented brain. What Is Memory? When an event happens, when you learn something, ...

  7. Diagenesis characteristics and their influence on Porosity and Permeability of sandstone from Yingcheng Formation in Jinshan field

    ZHANG Ruiyao,GAO Fuhong; ZHANG Zhongyue


    In order to understand the diagenesis and its influence on Porosity and Permeability of sandstones from Yingcheng Formation in Jinshan field,aPPlying thin sections,casting and scanning electron microscoPe, the authors studied PetrograPhy,diagenesis,Porosity and Permeability of Yingcheng Formation sandstone reser-voir. The results show that the reservoir of Yingcheng Formation is mainly comPosed of lithic arkoses. Sand-stones exPerienced comPaction,Pressolution,cementation,metasomatism and dissolution. The Primary Pores of the sandstones are undeveloPed;most of Pores are the secondary Pores,which are mainly intragranular dissolu-tion Pores in feldsPar and debris. The comPaction and cementation reduced the Primary Pores in sandstones,the Porosity and Permeability decreased;while the dissolution formed the secondary Pores,resulting in the Porosity and Permeability increase. Due to comPaction and cementation,the Porosity and Permeability are reduced with increasing of dePth. There exists an abnormal enlargement of Porosity and Permeability within a dePth range 2 310-2 450 m. In combination with analysis of Petrology,the dissolution of feldsPar and debris is most deve-loPed in the dePth range. Therefore,comPaction,cementation and dissolution are the imPortant factors which affect the Porosity and Permeability of sandstones.

  8. Diagenesis and porosity evolution of sandstone reservoirs in the East Ⅱ part of Sulige gas field, Ordos Basin

    Yang Renchao; Fan Aiping; Han Zuozhen; Wang Xiuping


    It is becoming an important controlling factor of gas exploration and exploitation in the east part of Sulige gas field in the Ordos Basin where the reservoir of main gas formations is tight sandstones.Employing experimental methods of slice identification,casting slice,scan electron microscope,and X-ray diffractions,we studied the characteristics of petrology and diagenesis on reservoirs in Shan1 section of Shanxi formation and He8 section of Shihezi formation of the Permian system in the East Ⅱ part of Sulige gas field.The results include:(1) the main sandstones in these areas are dominated by lithic sandstone and lithic silicarenite with low grade of maturity; (2) the diagenesis of sandstone in these areas mainly include compaction,cementation,corrosion and alteration.Conclusions are as follows:(1) the diagenetic stage reached period B of the middle diagenetic stage; (2) the early diagenetic compaction is one of the main factors to decreasing porosity:(3) the secondary pores formed by corrosion in acidity medium conditions in period A of the middle diagenetic stage can distinctly ameliorate the poor reservoir capability of sandstone and; (4) cementation in period B of the middle diagenetic stage is the most important factor leading to poor physical property of sandstone reservoirs.

  9. On the origin and early diagenesis of early Triassic carbonate mud (Dolomites, Italy)

    Preto, Nereo; Westphal, Hildegard; Birgel, Daniel; Carampin, Raul; Dal Corso, Jacopo; Gattolin, Giovanni; Montinaro, Alice; Peckmann, Jörn


    The earliest Triassic (early Induan) deposits of the Italian Southern Alps are shallow water oolites, and lime-mudstone formed in an open shelf (mid to outer carbonate ramp) sedimentary environment, deposited after the end-Permian extinction that killed all carbonate producers. The origin of these lime-mudstones is thus enigmatic. We used a multidisciplinary petrographic and geochemical approach to identify the origin and early diagenesis of early Triassic lime-mudstones of the Dolomites (Northern Italy). This fine carbonate is made of pitted crystals of microsparite, ~ 25 μm in diameter, exhibiting zonation both in fluorescence and cathodoluminescence. Field and standard petrographic observations exclude an origin from fragmentation or abrasion of carbonate grains. Strontium content, measured in-situ with electron microprobe, has a bimodal distribution with values locally as high as > 4000 ppm. Lipid biomarker analysis revealed molecular fossils of bacteria (terminally-branched alkanes, hopanes, and scarce methylhopanes) along with compounds of low source specificity (n-alkanes), whereas biomarkers of algae (steranes) were not detected. This suggests that, differently from modern Caribbean shelfs, this fine carbonate did not originate from the disgregation of green algae. A Pristane to Phytane ratio < 1 also suggests deposition under anoxic conditions, in agreement with the known status of "superanoxia" of earliest Triassic oceans. Overall, our observations suggest an aragonitic mineralogy of the carbonate mud, followed by calcite replacement and cementation in the marine burial early diagenetic environment. Our data strongly suggest that the early Triassic carbonate mud of the Dolomites was precipitated in the water column, similarly to the modern whitings of the Bahamas, and then settled on a shelf bottom below wave base. Our study shows that these lime-mudstones contain aragonite replaced by calcite and calcite cement, in variable proportions. The δ13C of

  10. Glass shards, pumice fragments and volcanic aerosol particles - diagenesis a recorder of volcanic activity?

    Obenholzner, J. H.; Schroettner, H.; Poelt, P.; Delgado, H.


    Detailed SEM/EDS studies of Triassic (Southern Alps, A, I, Sl) and Miocene (Mixteca Alta, Mexico) tuffs revealed that volcanic glass shards can be replaced by zeolites (analcite), chlorites and smectites preserving the shape of primary shards (1). The Triassic pyroclastic deposits have been incorporated in the pre-Alpine burial diagenesis, the Miocene pyroclastic deposits are bentonites. The volcanologist is impressed by the circumstances that million years old pyroclast relict textures can be sized. Shape parameters obtained by image analysis can be compared with much younger pyroclastic deposits (2). Both deposits have not been effected by shearing. The alteration of pumice fragments of Triassic age is not a simple replacement process. Intergrowth of different illites and chlorites and probably vesicle filling by SiO2 and subsequent overgrowth make a reconstruction sometimes difficult. These processes are accompanied by the formation of REE-, Y- and Zr-bearing minerals as well as with the alteration of zircons. Studies of recently erupted ash from Popocatepetl volcano reveal the presence of a variety of µm-sized contact-metamorphosed clasts being a part of the volcanic ash (3). Such clasts should be present in many older pyroclastic deposits, especially where volcanoes had been situated on massive sedimentary units providing contact metamorphism in the realm of a magma chamber or during magma ascent. Volcanic aerosol particles collected in 1997 from the passively degassing plume of Popocatepetl volcano revealed in FESEM/EDS analysis (H. Schroettner and P. Poelt) a wide spectrum of fluffy, spherical and coagulated spherical particles (µm-sized). Under pre-vacuum conditions they remained stable for ca. 3 years (3). In nature the fate of these particles in the atmosphere is unknown. Are there relicts in marine, lacustrine sediments and ice cores, which could be used as proxies of volcanic activity? (1) Obenholzner &Heiken,1999. Ann.Naturhist.Mus.Wien, 100 A, 13

  11. Structural diagenesis in Upper Carboniferous tight gas sandstones. Lessons learned from the Piesberg analog study

    Steindorf, P.; Hoehne, M.; Becker, S.; Hilgers, C. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Koehrer, B. [Wintershall Holding GmbH, Barnstorf (Germany)


    unconventional reservoir properties at a subseismic scale, considering both the alteration and evolution of pore space during diagenesis and the formation of structures. Combined with well-log and core data, uncertainties in 3D-reservoir modeling parameters and fluid migration pathways from seismic- to micro-scale of analogous subsurface tight gas reservoirs may be significantly reduced. (orig.)

  12. Sedimentological Aspects and Diagenetic Alterations of Beda "C" , Southwestern Sirt Basin, Libya

    Hlal, Osama


    The rock sequence of Tertiary Lower Beda Formation Beda "C" of southwest NC74B block in Sirt Basin has considered subdivided into facies and subfacies . These facies are dominated by muddy carbonates, such as skeletal mudstones, wackestones, and packstones with dolomites and anhydrite. Rock textures, faunal assemblages and sedimentary structures suggest open to partly open to shallow marine, lagoonal shelf , and upper subtidal to lower supratidal (Preitidal) environments. The Beda "C" Member represents a shallowing-upward sequence typical of lagoonal and tidal flat environments marked at the top by sabkha and brackish-water sediments. Petrographic and microfossils studies have been made by means of microscopic examination of (24) thin section. Microfossils include benthonic foraminifera, in addition ostracods, molluscs, echinoderms, and bryozoans. Dolomite, where present, is finely crystalline and an early replacement product. Anhydrite occurs as nodular, indicating supratidal sabkha deposition. Compaction, micritzation , dolomitization, cementation, and dissolution resulted in alteration and obliteration of primary sedimentary structures of the Beda "C" Member facies and subfacies. The study area is marked by several horsts and grabens; due to extensional tectonic activity. The area was tectonically active throughout the Tertiary period. Primary porosity is mainly interagranular, and dissolution diagenetic processes are significant enhancing the porosity. Primary porosity is intergranular and intragranular, and secondary processes are characterized by dissolution, intercrystalline, fracture. Diagenesis, through solution leaching and dolomitization, contributed greatly to development of porosity. Anhydrite occurs as replacement in top Member indicating supratidal deposition using a regular petrographic microscope, SEM and XRD analysis.

  13. Sedimentology, Petrography and Microfacies of the Paleogene Carbonate Sequence - Yaxcopoil-1 Borehole (Chicxulub, Yucatan)

    Escobar-Sanchez, E.; Fucugauchi, J. U.


    Chicxulub crater is one the three largest known impact craters on Earth, formed 66 Ma-old, with multi-ring basin morphology. Crater is located in northwestern Yucatan, southern Gulf of Mexico, with rim diameter of 200 km and crater center at Chicxulub Perto in the coastline. It is buried beneath the carbonate and evaporitic Cenozoic sequence. Study of the structure requires geophysics and drilling, with several boreholes drilled in the peninsula. The Yaxcopoil-1 borehole was drilled south of Merida, about 62 km from center, as part of the Chicxulub Scientific Drilling Program. One of the main objectives was to determine the role of the Chicxulub impact event in the K/Pg mass extinction and boundary events. We present a sedimentological and petrological study of the carbonate sequence in the interval from 404 m to 792 m overlying the K/Pg boundary. The well reached a depth of 1510.6 m. In this interval, we identified twelve units marked by different lithological and sedimentological changes, and supplemented by thin section analysis. Facies are composed mainly of marls, argillaceous, limestones, dolomitized limestones, calcareous breccias and calcarenites with shales thin beds. From the microfacies study we observed several major changes in the microfacies. From bottom of the sequence several textural changes cyclic from mudstone to bioclastic planktic foraminiferal wackestone, bioclastic packstone and some bioclastic grainstone. Two textures dominated in the calcareous sequence: bioclastic wackestone and packstone microfacies. From the microfacies study, we derived inferences on stable environmental conditions. We observed benthic and planktic foraminiferal layers. The benthic foraminifera strongly depend on environmental parameters, such as nutrient supply or oxygenation of the sea bottom water in the Paleocene and Eocene. Changes suggest occurrence of a progradational event, with a relative increase in sea level very slowly, with the sediment enough to overcome

  14. Lake sedimentological and plant ecological development across the Early Danian hyperthermal, Boltysh Impact Crater, Ukraine

    Ebinghaus, Alena; Jolley, David; Andrews, Steven; Kemp, David


    Past hyperthermals and associated negative carbon isotope excursions (CIEs) are inferred to have had significant impact on marine environments; however the formation and changes of terrestrial ecosystems across hyperthermals are less well constrained due to the lack of complete and high-resolution data. The Boltysh impact crater, Ukraine, which formed at the Cretaceous/Palaeogene (K/Pg) boundary at the northern margin of the Tethys Ocean, contains a >400 m thick unique and detailed lacustrine rock record of the Early Danian Dan-C2 hyperthermal. Based on a borehole (hole 42/11) drilled in the central part of the crater, we use a combination of sedimentological, palynological and carbon isotope data to 1) characterise and reconstruct lake formation and associated plant ecosystems, and 2) to assess lake sedimentological and ecological response to climatic variabilities during warming. Based on detailed facies analysis, 3 major gradual stages of lake formation are identified, indicating a strong relationship to carbon isotope shifts and associated climatic trends. Initial pre-excursion sedimentation was controlled by crater morphology and crater rim erosion transporting high amount of sediment into a shallow fresh water lake. During the negative excursion, sediment supply was increasingly characterised by inflow-evaporation ratio variabilities which affected seasonal stratification patterns and longer-term lake levels. An inferred increase in atmospheric pCO2 during the CIE, together with increasing mean annual temperatures, was likely responsible for periodic increases in bioproductivity. Palynological analyses demonstrate a gradual shift from mesic humid dominated vegetation to winterwet savannah-type vegetation at this stage, associated with an increase in mean annual temperatures and decrease in moisture availability. The positive excursion (recovery) and post-excursion stage is characterised by increased abundance of temperate mesic humid taxa. This cooling trend

  15. Diagenesis of magnetic minerals in a gas hydrate/cold seep environment off the Krishna-Godavari basin, Bay of Bengal

    Dewangan, P.; Basavaiah, N.; Badesab, F.K.; Usapkar, A.; Mazumdar, A.; Joshi, R.; Ramprasad, T.

    Detailed magnetic measurements of the core (MD161/8) located in the vicinity of Site NGHP-01-10 was carried out, where approx. 128 m of hydrate is confirmed by drilling/coring, to understand the diagenesis of magnetic minerals in a gas hydrates...

  16. Sedimentological recorders of the 2013 Typhoon Haiyan storm surge from contrasting Philippine coastal landscapes

    Soria, J. L.; Switzer, A.; Siringan, F. P.; Pilarczyk, J.; Li, L.


    Typhoon Haiyan in 2013 was an extremely intense and fast moving typhoon. It claimed more than 6000 lives, caused widespread damage, and affected more than 16 million people along its path in central Philippines. Overwash associated with the 5 to 8 m storm surge of Typhoon Haiyan also left behind a variety of geomorphic and sedimentological imprints, which provide a valuable dataset for modern storm deposits in different landform settings. Here we only present a synthesis of the sedimentological imprints from sites that span clastic, mixed clastic-carbonate, and non-clastic carbonate coasts, and were affected by contrasting surge mechanisms. On the sheltered clastic coast where overwash was dominated by wind-induced setup surge, the overwash sediments occur as a sand unit of no more than 20 cm near the shore, and then spread into sub-cm thin sandsheet that blanket pre-Haiyan soil surfaces up to 1.6 km inland. Thicker sections of the overwash sand exhibit sharp depositional contacts, planar stratification, and generally coarsen upward and fine landward. On the mixed clastic-carbonate coast, the Typhoon Haiyan deposits are generally thin (coast that was affected by a wave-dominated setup surge, the overwash sediments include two distinct assemblages: carbonate boulders now occupying the reef flat surface, and a sand sheet that blanketed the coastal plain up to 300 m distance inland. On the open coast, inverse modeling of flow velocities derived from boulder dimensions, sediment thickness, and grain size distributions indicate that the storm surge travelled across the wide reef flat and inundated the coast with flow velocities exceeding 4 ms-1. The sediment data support the tsunami-like surge characteristics of Haiyan, and although Haiyan's overwash sediments are clearly representative of Philippine modern storm deposits, they should however be used with caution in the interpretation of the geologic record. This cautionary note highlights the continuing issue of

  17. Sedimentological characteristics of the surficial deposits of the Jal Az-Zor area, Kuwait

    Al-Bakri, D.; Kittaneh, W.; Shublaq, W.


    The purpose of this article is to discuss the nature and characteristics of the surface geology of the Jal Az-Zor escarpment and the adjacent area, to better understand the sedimentology of desert landforms, and the main factors controlling depositional and diagenetic processes active in this environment. The oldest outcrops along the face of the escarpment are the sand and sandstone sequences of the Mutla and Jal Az-Zor Formations of the Kuwait Group (Neogene). Gravelly deposits of the upper member of the Kuwait Group, Dibdibba Formation (Pleistocene) are restricted to a few hillocks and ridges in the summit area of the escarpment. The Neogene deposits in most of the study area are overlain by a veneer of unconsolidated Holocene sediments. These were classified, according to their morphological setting and field occurrence, into: coastal deposits (intertidal mud, sabkha deposits, and sand dunes) and inland deposits (sand drifts, slope deposits, wadi fills, residual deposits and playa deposits). Wind-born quartzitic sand is the most common Holocene sediment in the study area indicating the dominance of the aeolian processes. Gypsum and carbonate present as cementing materials or in the form of gypcrete and calcrete, respectively, are characteristic sedimentological features of the pre-Holocene deposits. Gypcrete and gypsum cement are abundant in the upper section of the escarpment and decreases downward, whereas the carbonate (calcrete) shows a reverse pattern, i.e., it becomes more dominant in the lower section of the escarpment. The source of sulphate ions in the groundwater that is responsible for the development of gypcrete is believed to be the evaporites in the lower section of the Neogene sequence. The source of ions for the formation of calcrete and calcite cement is less understood due to the lack of significant primary carbonates in the near-surface deposits. It is believed that the nature and distribution of the chemically precipitated material (gypsum

  18. The effects of diagenesis and dolomitization on Ca and Mg isotopes in marine platform carbonates: Implications for the geochemical cycles of Ca and Mg

    Fantle, Matthew S.; Higgins, John


    The Ca, Mg, O, and C isotopic and trace elemental compositions of marine limestones and dolostones from ODP Site 1196A, which range in depth (∼58 to 627 mbsf) and in depositional age (∼5 and 23 Ma), are presented. The objectives of the study are to explore the potential for non-traditional isotope systems to fingerprint diagenesis, to quantify the extent to which geochemical proxies are altered during diagenesis, and to investigate the importance of diagenesis within the global Ca and Mg geochemical cycles. The data suggest that Ca, which has a relatively high solid to fluid mass ratio, can be isotopically altered during diagenesis. In addition, the alteration of Ca correlates with the alteration of Mg in such a way that both can serve as useful tools for deciphering diagenesis in ancient rocks. Bulk carbonate δ44Ca values vary between 0.60 and 1.31‰ (SRM-915a scale); the average limestone δ44Ca is 0.97 ± 0.24‰ (1SD), identical within error to the average dolostone (1.03 ± 0.15 1SD ‰). Magnesium isotopic compositions (δ26Mg, DSM-3 scale) range between -2.59‰ and -3.91‰, and limestones (-3.60 ± 0.25‰) and dolostones (-2.68 ± 0.07‰) are isotopically distinct. Carbon isotopic compositions (δ13C, PDB scale) vary between 0.86‰ and 2.47‰, with average limestone (1.96 ± 0.31‰) marginally offset relative to average dolostone (1.68 ± 0.57‰). The oxygen isotopic compositions (δ18O, PDB scale) of limestones (-1.22 ± 0.94‰) are substantially lower than the dolostones measured (2.72 ± 1.07‰). The isotopic data from 1196A suggest distinct and coherent trends in isotopic and elemental compositions that are interpreted in terms of diagenetic trajectories. Numerical modeling supports the contention that such trends can be interpreted as diagenetic, and suggests that the appropriate distribution coefficient (KMg) associated with limestone diagenesis is ∼1 to 5 × 10-3, distinctly lower than those values (>0.015) reported in laboratory

  19. Occurrence of Organic Matter in Calcimicrobialites across Permian-Triassic Boundary in Huayingshan Region, Sichuan, South China

    Yang Hao; Wang Yongbiao; Chen Lin


    Calcimicrobialites across the Permian-Triassic boundary in Huayingshan (华蓥山) region were investigated using the fluorescence microscopic measurements to understand the occurrence of organic matter. The microbialites are composed of micrite matrix and coarse spar cement. Abundant rhombic or magnetic needle-like carbonate minerals were observed adrift within the cement. The fluorescence microscopic measurement indicates the micrite matrix in microbialites shows the most abundant organic matter, with the rhombic or magnetic needle-like carbonate minerals and coarse spar cement coming to the 2nd and the 3rd, respectively. Organic matter is mainly preserved in the space between the grains of the micrite minerals but almost evenly distributed in the rhombic or magnetic needle-like carbonate minerals. As one of the common diagenesis types, dolomitization is observed to occur in the microbialites in Huayingshan. However, the carbonate cement in microbialites still has high content of element Sr as shown by the microprobe analysis, reflecting that the dolomitization might have happened in a restricted environment. Observation under the fluorescence microscope shows that dolomitization just led to the redistribution of organic matter in the grain space of dolomite minerals, inferring that the diagenesis has a slight effect on the preservation, and thus on the content of organic matter in the microbialites.

  20. The sedimentology of a palaeo ice stream bed: an in-depth analysis of the Wielkopolska (Poland) MSGL field

    Spagnolo, Matteo; Phillips, Emrys; Piotrowski, Jan A.; Rea, Brice; Carr, Simon; Ely, Jeremy; Ribolini, Adriano; Szuman, Izabela


    Ice streams are fast flowing (up to 1000s m per year) corridors of ice within ice sheets. They are the main arteries through which ice sheets lose mass, accounting for up to 90% of Antarctic discharge. Ice streams are also dynamic and can widen, migrate or shut down on decadal timescales. One of the key controlling factors on ice stream behaviour is the interaction with a soft sedimentary bed, but the exact mechanism of this interaction is far from known or well understood. Studies on the sedimentology of ice stream bed are challenging in present-day glaciated regions or in offshore palaeo-settings. However, some good examples of onshore and 'relatively' easy-to-access palaeo ice stream beds do exist. In Europe, one of these settings is in Poland, near the town of Poznan, in the Wielkopolska region. Mega-Scale Glacial Lineations (MSGLs), the characterising landform signature of ice stream beds, have been investigated using state of the art sedimentological techniques. These include, extensive investigation of multiple trenches excavated along the crests and flanks of MSGL and ground penetrating radar profiling of large sections of the MSGL field. Micro-sedimentological characterisation via thin sections, AMS and CT scans, as well as various lab analyses, including granulometry and mineralogy were also undertaken. Results indicate a homogeneous facies (to >3m), across all depths and locations within the palaeo ice stream bed. This has profound implications on the formation of MSGLs and the dynamics of ice stream flow.

  1. Reconstruction of the diagenesis of the fluvial-lacustrine- deltaic sandstones and its influence on the reservoir quality evolution-- Evidence from Jurassic and Triassic sandstones, Yanchang Oil Field, Ordos Basin


    The reservoir quality of Jurassic and Triassic fluvial and lacustrine-deltaic sandstones of the Yanchang Oil Field in the Ordos Basin is strongly influenced by the burial history and facies-related diagenetic events. The fluvial sandstones have a higher average porosity (14.8%) and a higher permeability (12.7×10?3 ?m2) than those of the deltaic sandstones (9.8% and 5.8 ×10?3 ?m2, respectively). The burial compaction, which resulted in 15% and 20% porosity loss for Jurassic and Triassic sandstones, respectively, is the main factor causing the loss of porosity both for the Jurassic and Triassic sandstones. Among the cements, carbonate is the main one that reduced the reservoir quality of the sandstones. The organic acidic fluid derived from organic matter in the source rocks, the inorganic fluid from rock-water reaction during the late diagenesis, and meteoric waters during the epidiagenesis resulted in the formation of dissolution porosity, which is the main reason for the enhancement of reservoir-quality.

  2. Critical zone study in Korea: integration of hydrogeology, mineralogy, sedimentology and molecular biogeochemistry

    Lee, J. Y.; Kwon, K.; Jo, K. N.; Lee, J. S.


    Critical Zone (CZ) is the topmost layer of the Earth ranging from the vegetation canopy down to the soil, groundwater, and bedrock that sustains our ecosystem including human life. This CZ is being greatly influenced by the climate change and anthropogenic forces. We introduce the Critical Zone Frontier Research Laboratory (CFRL), a critical zone research lab recently funded by the Korean government for 2015-2020. The objective of CFRL is to unravel the relationships between climate and CZ changes to propose a prediction model for future responses of CZ to climate change. For this ultimate goal, we establish multiple CZ observatories in Kangwon areas and investigate soil, groundwater, and cave environments by integration of hydrogeology, mineralogy, sedimentology and molecular biogeochemistry. This study will enhance our understanding about CZ and local resolution of a climate change model. This research is financially supported by the Basic Research Laboratory Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT and Future Planning.

  3. High-resolution sedimentological and subsidence analysis of the Late Neogene, Pannonian Basin, Hungary

    Juhasz, E.; Muller, P.; Toth-Makk, A.; Hamor, T.; Farkas-Bulla, J.; Suto-Szentai, M.; Phillips, R.L.; Ricketts, B.


    Detailed sedimentological and paleontological analyses were carried out on more than 13,000 m of core from ten boreholes in the Late Neogene sediments of the Pannonian Basin, Hungary. These data provide the basis for determining the character of high-order depositional cycles and their stacking patterns. In the Late Neogene sediments of the Pannonian Basin there are two third-order sequences: the Late Miocene and the Pliocene ones. The Miocene sequence shows a regressive, upward-coarsening trend. There are four distinguishable sedimentary units in this sequence: the basal transgressive, the lower aggradational, the progradational and the upper aggradational units. The Pliocene sequence is also of aggradational character. The progradation does not coincide in time in the wells within the basin. The character of the relative water-level curves is similar throughout the basin but shows only very faint similarity to the sea-level curve. Therefore, it is unlikely that eustasy played any significant role in the pattern of basin filling. Rather, the dominant controls were the rapidly changing basin subsidence and high sedimentation rates, together with possible climatic factors.

  4. Stratigraphy, sedimentology and paleontology of lower Eocene San Jose formation, central San Juan basin, New Mexico

    Lucas, S.G.; Smith, L.N. (New Mexico Museum of Natural History, Albuquerque (USA))


    The lower Eocene San Jose Formation in the central portion of the San Juan basin (Gobernador-Vigas Canyon area) consists of the Cuba Mesa, Regina, Llaves, and Tapicitos Members. Well log data indicate that, from its 100-m thickness, the Cuba Mesa Member thins toward the basin center and pinches out to the northeast by lat. 36{degree}40'N, long. 107{degree}19'W. The Regina Member has the most extensive outcrops in the central basin, and it decreases in sandstone/mud rock ratio to the north. The Llaves and Tapicitos Members occur only at the highest elevations, are thin due to erosion, and are not mappable as separate units. Well log data and 1,275 m of measured stratigraphic section in the Regina, Llaves, and Tapicitos Members indicate these strata are composed of approximately 35% medium to coarse-grained sandstone and 65% fine-grained sandstone and mud rock. Sedimentology and sediment-dispersal patterns indicate deposition by generally south-flowing streams that had sources to the northwest, northeast, and east. Low-sinuosity, sand-bedded, braided( ) streams shifted laterally across about 1 km-wide channel belts to produce sheet sandstones that are prominent throughout the San Jose Formation. Subtle levees separated channel environments from floodplain and local lacustrine areas. Avulsion relocated channels periodically to areas on the floodplain, resulting in the typically disconnected sheet sandstones within muddy overbank deposits of the Regina Member.

  5. Biostratigraphy, sedimentology and paleoenvironments of the northern Danube Basin: Ratkovce 1 well case study

    Rybár Samuel


    Full Text Available The Ratkovce 1 well, drilled in the Blatné depocenter of the northern Danube Basin penetrated the Miocene sedimentary record with a total thickness of 2000 m. Biostratigraphically, the NN4, NN5 and NN6 Zones of calcareous nannoplankton were documented; CPN7 and CPN8 foraminifer Zones (N9, 10, 11 of the global foraminiferal zonation; and MMi4a; MMi5 and MMi6 of the Mediterranean foraminiferal zonation were recognized. Sedimentology was based on description of well core material, and together with SP and RT logs, used to characterize paleoenvironmental conditions of the deposition. Five sedimentary facies were reconstructed: (1 fan-delta to onshore environment which developed during the Lower Badenian; (2 followed by the Lower Badenian proximal slope gravity currents sediments; (3 distal slope turbidites were deposited in the Lower and Upper Badenian; (4 at the very end of the Upper Badenian and during the Sarmatian a coastal plain of normal marine to brackish environment developed; (5 sedimentation finished with the Pannonian-Pliocene shallow lacustrine to alluvial plain deposits. The provenance analysis records that the sediment of the well-cores was derived from crystalline basement granitoides and gneisses and from the Permian to Lower Cretaceous sedimentary cover and nappe units of the Western Carpathians and the Eastern Alps. Moreover, the Lower Badenian volcanism was an important source of sediments in the lower part of the sequence.

  6. Sedimentological characters of the mangrove ecosystem of Kali estuary, Karwar, west coast of India

    V. Kumar


    Full Text Available Estuarine mangroves give natural support to the protection of the riverbanks, due to their accumulative nature. To study this effect, it is necessary to measure sedimentation rates under estuarine mangroves. Sediment plays an important role in the storage and release of nutrient into the water column, the mineralization of organic carbon deposits by various kinds of microbes. In association with other parameters, the sediment is responsible for the variations in densities of majority of benthic organisms. Regular monthly collections of bottom water and sediment were made for a period thirteen months from January 2008 and January 2009 at five different study sites using the motorized outrigger canoe. The present investigation encompassed collection of data pertaining to various aspects of sedimentology. Sediment temperature varied from 25.100c to 30.450c. The pH ranged between 6.18 to 8.30. Organic carbon Varied between 2.06 to 29.45%, moisture content varied from 20.10% to 41.88. Values of interstitial water content is varied between 1.60% to 30.95%. Wide variation in the percentage composition of sand (28.45% to 80.10%, silt (12.78% to 54.28%, and clay (3.66% to 33.63% was observed.

  7. New interpretation of the Gran Dolina-TD6 bearing Homo antecessor deposits through sedimentological analysis

    Campaña, I.; Pérez-González, A.; Benito-Calvo, A.; Rosell, J.; Blasco, R.; de Castro, J. M. Bermúdez; Carbonell, E.; Arsuaga, J. L.


    Gran Dolina is a cavity infilled by at least 25 m of Pleistocene sediments. This sequence contains the TD6 stratigraphic unit, whose records include around 170 hominin bones that have allowed the definition of a new species, Homo antecessor. This fossil accumulation was studied as a single assemblage and interpreted as a succession of several human home bases. We propose a complete stratigraphic context and sedimentological interpretation for TD6, analyzing the relationships between the sedimentary facies, the clasts and archaeo-palaeontological remains. The TD6 unit has been divided into three sub-units and 13 layers. Nine sedimentary facies have been defined. Hominin remains appear related to three different sedimentary facies: debris flow facies, channel facies and floodplain facies. They show three kinds of distribution: first a group of scattered fossils, then a group with layers of fossils in fluvial facies, and third a group with a layer of fossils in mixed fluvial and gravity flow facies. The results of this work suggest that some of these hominin remains accumulated in the cave by geological processes, coming from the adjacent slope above the cave or the cave entry, as the palaeogeography and sedimentary characteristics of these allochthonous facies suggest.

  8. Geomorphological and sedimentological record of accelerated deglaciation of small mountain glacier, Ragnarbreen, Svalbard

    Ewertowski, Marek


    Most of the Svalbrad glaciers have been in retreat since the end of the Little Ice Age (LIA). Hence, they give a good opportunity to study the geomorphological and sedimentological record of deglaciation. The aim of the study is to describe main landsystem elements of Ragnar glacier and relate them to different stages of the glacier recession. The Ragnar glacier is located in the Svalbard archipelago, in the central part of the West Spitsbergen Isle, in the north branch of Billefjorden. Ragnar is a small (~ 6 km2), outlet glacier, which current clean ice edge has retreated ca. 1500 m from the position related to the maximum LIA extent. Fieldworks of the study comprised detailed geomorphological mapping and sedimentary works. Four main elements of the landsystem of the Ragnar glacier can be distinguished: 1) Clean glacier surface. Currently, the ice surface of Ragnar glacier is almost completely debris-free and with only several supraglacial streams. 2) Ice-marginal lake. The lake started to form after 1980 year. Since that time, its length has reached 1000 m. Distant (from the ice-edge) part of the lake is shallow (changes in distribution of the sediments and landforms. They also add some premises that in the first stage of deglaciation debris flow and other mass wasting processes are most common. In the later phase glaciolacustrine and glaciofluvial deposition also plays important role in transformation of landforms and sediments.

  9. The 1957 Valencia flood: hydrological and sedimentological reconstruction and comparison to the current situation

    C. Puertes


    Full Text Available This work aims to improve the knowledge of the flood that took place in Valencia, Spain, in 1957. In other words, the aim is to test if it is possible to explain the flood waves with the incorporation of sediment cycle to a distributed hydrological model. Furthermore, this work aims to be aware of the current consequences of a similar event, taking into account land use changes, particularly, the urban rise in the lower basin, and the current flood defenses of the city. To do this, the hydrological model was implemented in the current basin situation. Once implemented, a reconstruction of precipitation at hourly discretization for the 1957 event was made and the sedimentological sub-model was calibrated. Then, the hydrographs in the chosen points were obtained. Finally, a simulation using the 1957 precipitation in the current basin situation was made, in order to be aware of the current consequences.

  10. Little Ice Age glacial geomorphology and sedimentology of Portage Glacier, South-Central Alaska

    Carlos Córdova


    Full Text Available The study of glacial landforms and deposits is important, as it isdifficult to observe processes under modern glaciers and ice-sheets. Thus landscapes and sediments that are the product of present glaciation can give insight into processes that occurred during Pleistocene times. This study investigates the genesis of little ice age glacial landforms present in Portage Glacier, South-Central Alaska. The present day moraine morphology and sedimentology in Portage Glacier valley reveals the presence of two types of till and moraines. The clast-rich sandy diamicton present on the 1852 moraine is interpreted to be a basal till indicating this feature is a pushmoraine representing an advance or a standstill position of Portage Glacier in 1852. The moderately sorted gray sandy boulder gravel present on the 1900 and 1922 moraines is interpreted to be an ice-marginal deposit (ablation till with a mixture of supraglacial and glaciofluvial sediments deposited by slumping and stream sortingprocesses. All of these features are interpreted to be ablation moraines representing glacier retreat and moraine building in 1900 and1922.

  11. Tertiary tectonic and sedimentological evolution of the South Carpathians foredeep: tectonic vs eustatic control

    Rabagia, T. [Prospectiuni S.A., Hydrocarbon Div., Bucharest (Romania); Matenco, L. [Bucharest Univ., Faculty of Geology and Geophysics, Bucharest (Romania)


    A detailed seismic sequence stratigraphy study based on the dense network of seismic profiles is integrated with structural observations from interpreted geological sections to derive a tectonic and sedimentological model for the Miocene-Pliocene evolution of the South Carpathians foredeep (Getic Depression). Following Paleogene and older orogenic phases, the first tectonic event which affected the studied areas was characterised by Early Miocene large scale extension to transtension which is responsible for the opening of the Getic Depression as a dextral pull-apart basin. Further Middle Miocene contraction caused WNW-ESE oriented thrusts and associated piggy-back basins. The last tectonic episode recognised in the studied areas relates to general transpressive deformations during the Late Miocene-Early Pliocene interval, a first NW-SE oriented dextral episode is followed by second N-S sinistral deformations. The detailed sequence stratigraphy study allows for the definition of the dominant tectonic control of the sedimentary sequences in foreland basins. A eustatic control may be associated, but has a clear subordinated character. (Author)

  12. Diagenesis, provenance and reservoir quality of Triassic TAGI sandstones from Ourhoud field, Berkine (Ghadames) Basin, Algeria

    Rossi, C.; Arribas, J.; Tortosa, A. [Universidad Complutense de Madrid, (Spain). Departamento de Petrologia y Geoquimica; Kalin, O. [Universidad Complutense, Madrid (Spain). Departamento de Paleontologia


    The Triassic TAGI (Trias Argilo-Greseux Inferieur) fluvial sandstones are the main oil reservoirs in the Berkine Basin, Algeria. Nonetheless, their provenance and diagenesis, and their impact on reservoir quality, are virtually unknown. Samples from the Ourhoud field, representing the Lower, Middle and Upper TAGI subunits, were studied using a combination of petrographic, mineralogical and geochemical techniques. The Lower TAGI sandstones have an average framework composition of Q{sub 98.3}F{sub 0.6}R{sub 1.1} and 95% of the quartz grains are monocrystalline. By contrast, the Middle-Upper TAGI sandstones have an average framework composition of Q{sub 88.3}F{sub 9.8}R{sub 1.9} and 79% of the quartz grains are monocrystalline. The Lower TAGI quartz arenites derived from Paleozoic siliclastic rocks, whereas the Middle-Upper TAGI subarkoses originated mainly from metamorphic terrains. This change in provenance is a potential criterion for correlation within the TAGI. Also, this change has contributed to the significantly different diagenetic paths followed by the Lower TAGI quartz arenites and the Middle-Upper TAGI subarkoses. Grain-coating illitic clays are abundant in the Lower TAGI, where they exert a critical control on reservoir quality. These clays are interpreted as pedogenic and/or infiltrated in origin and to have had, in part, smectitic precursors. Shallow burial Fe-dolomite cementation was favored in the downthrown block of the field-bounding fault, where it contributed to the poor reservoir quality. Magnesite-siderite cements are multiphase. The earliest generation is composed of Fe-rich magnesite that precipitated during shallow burial from hypersaline fluids with high Mg/Ca ratios, probably refluxed residual brines associated with the Liassic evaporites. Later magnesite-siderite generations precipitated during deeper burial from waters with progressively higher Fe/Mg ratios. Authigenic vermicular kaolin largely consists of dickite that replaced previously

  13. Experimental diagenesis: insights into aragonite to calcite transformation of Arctica islandica shells by hydrothermal treatment

    Casella, Laura A.; Griesshaber, Erika; Yin, Xiaofei; Ziegler, Andreas; Mavromatis, Vasileios; Müller, Dirk; Ritter, Ann-Christine; Hippler, Dorothee; Harper, Elizabeth M.; Dietzel, Martin; Immenhauser, Adrian; Schöne, Bernd R.; Angiolini, Lucia; Schmahl, Wolfgang W.


    Biomineralised hard parts form the most important physical fossil record of past environmental conditions. However, living organisms are not in thermodynamic equilibrium with their environment and create local chemical compartments within their bodies where physiologic processes such as biomineralisation take place. In generating their mineralised hard parts, most marine invertebrates produce metastable aragonite rather than the stable polymorph of CaCO3, calcite. After death of the organism the physiological conditions, which were present during biomineralisation, are not sustained any further and the system moves toward inorganic equilibrium with the surrounding inorganic geological system. Thus, during diagenesis the original biogenic structure of aragonitic tissue disappears and is replaced by inorganic structural features. In order to understand the diagenetic replacement of biogenic aragonite to non-biogenic calcite, we subjected Arctica islandica mollusc shells to hydrothermal alteration experiments. Experimental conditions were between 100 and 175 °C, with the main focus on 100 and 175 °C, reaction durations between 1 and 84 days, and alteration fluids simulating meteoric and burial waters, respectively. Detailed microstructural and geochemical data were collected for samples altered at 100 °C (and at 0.1 MPa pressure) for 28 days and for samples altered at 175 °C (and at 0.9 MPa pressure) for 7 and 84 days. During hydrothermal alteration at 100 °C for 28 days most but not the entire biopolymer matrix was destroyed, while shell aragonite and its characteristic microstructure was largely preserved. In all experiments up to 174 °C, there are no signs of a replacement reaction of shell aragonite to calcite in X-ray diffraction bulk analysis. At 175 °C the replacement reaction started after a dormant time of 4 days, and the original shell microstructure was almost completely overprinted by the aragonite to calcite replacement reaction after 10 days

  14. Depositional sequence analysis and sedimentologic modeling for improved prediction of Pennsylvanian reservoirs

    Watney, W.L.


    Reservoirs in the Lansing-Kansas City limestone result from complex interactions among paleotopography (deposition, concurrent structural deformation), sea level, and diagenesis. Analysis of reservoirs and surface and near-surface analogs has led to developing a {open_quotes}strandline grainstone model{close_quotes} in which relative sea-level stabilized during regressions, resulting in accumulation of multiple grainstone buildups along depositional strike. Resulting stratigraphy in these carbonate units are generally predictable correlating to inferred topographic elevation along the shelf. This model is a valuable predictive tool for (1) locating favorable reservoirs for exploration, and (2) anticipating internal properties of the reservoir for field development. Reservoirs in the Lansing-Kansas City limestones are developed in both oolitic and bioclastic grainstones, however, re-analysis of oomoldic reservoirs provides the greatest opportunity for developing bypassed oil. A new technique, the {open_quotes}Super{close_quotes} Pickett crossplot (formation resistivity vs. porosity) and its use in an integrated petrophysical characterization, has been developed to evaluate extractable oil remaining in these reservoirs. The manual method in combination with 3-D visualization and modeling can help to target production limiting heterogeneities in these complex reservoirs and moreover compute critical parameters for the field such as bulk volume water. Application of this technique indicates that from 6-9 million barrels of Lansing-Kansas City oil remain behind pipe in the Victory-Northeast Lemon Fields. Petroleum geologists are challenged to quantify inferred processes to aid in developing rationale geologically consistent models of sedimentation so that acceptable levels of prediction can be obtained.

  15. Diagenesis and Fluid Flow History in Sandstones of the Upper Permian Black Jack Formation, Gunnedah Basin, Eastern Australia

    BAI Guoping; John B. KEENE


    The fluid flow history during diagenesis of sandstones in the Upper Permian Black Jack Formation of the Gunnedah Basin has been investigated through integrated petrographic observations, fluid inclusion investigations and stable isotope analyses. The early precipitation of mixed-layer illite/smectite, siderite, calcite, ankerite and kaolin proceeded at the presence of Late Permian connate meteoric waters at temperatures of up to 60℃. These evolved connate pore waters were also parental to quartz, which formed at temperatures of up to 87℃. The phase of maximum burial was characterized by development of filamentous illite and late calcite at temperatures of up to ~90℃. Subsequent uplifting and cooling led to deep meteoric influx from surface, which in turn resulted in dissolution of labile grains and carbonate cements, and formation of second generation of kaolin. Dawsonite was the last diagenetic mineral precipitated and its formation is genetically related to deep-seated mamagtic sourced CO2.

  16. Early diagenesis of travertine deposits from the Tibetan Plateau - implications for 230Th/234U dating and palaeoenvironmental reconstruction

    Wang, Zhijun; Meyer, Michael; Hoffmann, Dirk; Spötl, Christoph; Aldenderfer, Mark; Sanders, Diethard


    Travertine is calcium carbonate precipitated from hydrothermal springs. These terrestrial carbonate deposits can be used as high-resolution archives for reconstructing palaeoclimatic and palaeoenvironmental change and are also suitable for uranium-series disequilibrium (230Th/234U) dating. In many instances such spring deposits are associated with archaeological remains (e.g. stone artifacts and other traces of prehistoric human activity) and are therefore of interest for palaeoclimatologists and archaeologists alike. However, travertines are often affected by early diagenesis that can impact on the closed-system U-series behavior and on their geochemical signature. Hence, careful evaluation of the travertine microfabrics is required before these types of hot spring deposits can be accurately dated and used for paleoenviromental reconstruction. The Tibetan plateau hosts numerous hydrothermal spring deposits that occur along neotectonic faults. In this study, samples were collected from two archaeological travertine sites, i.e. Chusang and Tirthapuri, located in southern and western Tibet, respectively. Microscopic analysis of thin sections reveals a wide variety of crystal fabrics, including micrite, microspar and sparite, the latter can be composed of columnar or mosaic crystals, respectively. Areas where dendritic crystals are preserved are identified in our micrographs as well. Many of the Chusang and Tirthapuri travertine samples are porous. Drusy sparite is rimming most of the pore walls and a complex succession of secondary calcite phases precipitated in these pore spaces as well. The different generations of pore cement comprise micrite and sparite that can be laminated or fibrous in character and show sometimes evidence of an aragonite precursor. Detrital material like quartz, feldspar and other grains as well as humic and fulvic acids have been washed into the travertine pores too. Based on our microscopic analysis a complex growth history can be

  17. Application of organic facies in sedimentological-stratigraphical model of the Oligo-Miocene and Miocene of the Campos Basin; Aplicacao da faciologia organica no modelo sedimentologico-estratigrafico do Oligo-Mioceno e Mioceno da Bacia de Campos

    Mendonca Filho, Joao Graciano; Mendonca, Joalice de Oliveira; Oliveira, Antonio Donizeti de; Torres, Jaqueline [Universidade Federal do Rio de Janeiro (UFRJ). Centro de Ciencias Exatas e da Natureza. Inst. de Geociencias (Brazil)], e-mails:,,,; Menezes, Taissa Rego [Centro de Pesquisas da Petrobras (CENPES), RJ (Brazil). P e D em Geociencias. Gerencia de Geoquimica], e-mail:; Santos, Viviane Sampaio Santiago dos; Arienti, Luci Maria [Centro de Pesquisas da Petrobras (CENPES), RJ (Brazil). P e D em Geociencias. Gerencia de Sedimentologia e Estratigrafia], e-mails:,


    This study integrates palynofacies analyses and the sedimentological and stratigraphic model of the Oligo-Miocene/Miocene siliciclastic deposits from the stratigraphic interval of the shallow continental platform up to the slope/basin of the Oligo-Miocene/ Miocene of the Campos Basin proposed. The main objective of the palynofacies study was to characterize the particulate sedimentary organic matter to obtain information about the proximal-distal relationship and the sedimentary organic matter preservation and depositional environmental conditions. The 158 core samples collected in 29 wells of the 9 oil production fields (Albacora, Barracuda, Marlim Sul, Marlim, Voador, Marlim Leste, Moreia and Albacora Leste), were studied. This technique provides information about the proximal-distal relationship and the paleoenvironmental conditions of deposition and preservation of sedimentary organic matter, to facilitate the evaluation and comparisons between the associations of particulate organic components. Thus, the palynofacies technique can be used as another tool in the characterization of depositional systems, based on the spatial and temporal distribution of sedimentary intervals. In general the palynofacies assemblages showed the predominance of the Phytoclast Group (terrestrial derived organic matter) at various degradation stages due to the selective preservation process diagnosed in the studied samples. Some samples, revealed high dinocysts percentages indicative of transgressive depositional conditions. From the obtained data, it was possible to characterize the stratigraphic sequences according to the distribution of particulate organic content (e.g. influence of fluvio-deltaic systems, oxygen system, regressive-transgressive tendencies of each sequence). Additional analyses of Total Organic Carbon (% wt) showed the control of the particulate components from the Phytoclast Group on the TOC (% wt) content, suggesting that the relative sea-level variation curves

  18. Diagenesis of tetrapyrrole pigments at Site 467 Leg 63 San Miguel Gap (offshore California): A detailed study

    Bennett, B.


    Sediments from DSDP Leg 63, Site 467 (San Miguel Gap, offshore California, USA) offer an unusual opportunity to study and quantify the distributional changes in tetrapyrrole pigment composition with burial depth. The samples available included an immature, wet and unconsolidated sample containing functionalised chlorins, to those approaching the onset of generation. The tetrapyrrole pigments have been quantified by UV/vis spectroscopy, while EIMS and HPLC were used to investigate the distributional changes. During this study a number of pigment types were encountered: (i) chlorins, (ii) free base alkyl and acid porphyrins, (iii) copper, nickel and vanadyl alkyl porphyrins, as well as their acid counterparts. Copper and vanadyl carboxylic acid porphyrins are reported for the first time in DSDP/IPOD sediments. Individual components have been examined by EIMS and HPLC coinjection with standards, as appropriate. During this study, free base C[sub 32] DPEP and C[sub 33] DPE, copper and nickel alkyl and acid porphyrins occurred in a wet and unconsolidated Upper Pliocene sediment (Section 18-5). Such a suite of porphyrins demonstrates that aromatisation, reduction of the C-13[sup 1] keto moiety present in all chlorophylls, decarboxylation and chelation can occur at a very early stage of diagenesis. The importance of thermal mechanisms occurring on components surviving early diagenesis is discussed in light of the findings herein. Copper alkyl porphyrins previously ascribed to an allochthonous source are now considered, along with porphyrin acid counterparts, as autochtonous components. The behaviour of Cu(II), Ni(II) and VO(II) species under differing redox conditions is discussed in relation to pigment preservation and the porphyrin distributions associated with these chelates. A C[sub 31] 15-17 ethanoporphyrin was tentatively assigned in all samples, indicated a chlorophyll c input to the sediments. A source, at least in part, from dinoflagellates is considered.

  19. Amino acid distribution in meteorites: diagenesis, extraction methods, and standard metrics in the search for extraterrestrial biosignatures.

    McDonald, Gene D; Storrie-Lombardi, Michael C


    The relative abundance of the protein amino acids has been previously investigated as a potential marker for biogenicity in meteoritic samples. However, these investigations were executed without a quantitative metric to evaluate distribution variations, and they did not account for the possibility of interdisciplinary systematic error arising from inter-laboratory differences in extraction and detection techniques. Principal component analysis (PCA), hierarchical cluster analysis (HCA), and stochastic probabilistic artificial neural networks (ANNs) were used to compare the distributions for nine protein amino acids previously reported for the Murchison carbonaceous chondrite, Mars meteorites (ALH84001, Nakhla, and EETA79001), prebiotic synthesis experiments, and terrestrial biota and sediments. These techniques allowed us (1) to identify a shift in terrestrial amino acid distributions secondary to diagenesis; (2) to detect differences in terrestrial distributions that may be systematic differences between extraction and analysis techniques in biological and geological laboratories; and (3) to determine that distributions in meteoritic samples appear more similar to prebiotic chemistry samples than they do to the terrestrial unaltered or diagenetic samples. Both diagenesis and putative interdisciplinary differences in analysis complicate interpretation of meteoritic amino acid distributions. We propose that the analysis of future samples from such diverse sources as meteoritic influx, sample return missions, and in situ exploration of Mars would be less ambiguous with adoption of standardized assay techniques, systematic inclusion of assay standards, and the use of a quantitative, probabilistic metric. We present here one such metric determined by sequential feature extraction and normalization (PCA), information-driven automated exploration of classification possibilities (HCA), and prediction of classification accuracy (ANNs).

  20. Sedimentological characteristics and depositional processes of sediment gravity flows in rift basins: The Palaeogene Dongying and Shahejie formations, Bohai Bay Basin, China

    Liu, Lei; Chen, Hongde; Zhong, Yijiang; Wang, Jun; Xu, Changgui; Chen, Anqing; Du, Xiaofeng


    Sediment gravity flow deposits are common, particularly in sandy formations, but their origin has been a matter of debate and there is no consensus about the classification of such deposits. However, sediment gravity flow sandstones are economically important and have the potential to meet a growing demand in oil and gas exploration, so there is a drive to better understand them. This study focuses on sediment gravity flow deposits identified from well cores in Palaeogene deposits from the Liaodong Bay Depression in Bohai Bay Basin, China. We classify the sediment gravity flow deposits into eight lithofacies using lithological characteristics, grain size, and sedimentary structures, and interpret the associated depositional processes. Based on the scale, spatial distribution, and contact relationships of sediment gravity flow deposits, we defined six types of lithofacies associations (LAs) that reflect transformation processes and depositional morphology: LA1 (unconfined proximal breccia deposits), LA2 (confined channel deposits), LA3 (braided-channel lobe deposits), LA4 (unconfined lobe deposits), LA5 (distal sheet deposits), and LA6 (non-channelized sheet deposits). Finally, we established three depositional models that reflect the sedimentological characteristics and depositional processes of sediment gravity flow deposits: (1) slope-apron gravel-rich depositional model, which involves cohesive debris flows deposited as LA1 and dilute turbidity currents deposited as LA5; (2) non-channelized surge-like turbidity current depositional model, which mainly comprises sandy slumping, suspended load dominated turbidity currents, and dilute turbidity currents deposited as LA5 and LA6; and (3) channelized subaqueous-fan depositional model, which consists of non-cohesive bedload dominated turbidity currents, suspended load dominated turbidity currents, and dilute turbidity currents deposited as LA2-LA5, originating from sustained extrabasinal turbidity currents

  1. Advances in the Role of Iron in Marine Sediments during Early Diagenesis%铁元素对海相沉积物早期成岩作用的影响

    刘喜停; 颜佳新


    铁元素是地壳中丰度最高的元素之一,在海相沉积物成岩过程中起着非常重要的作用.铁元素作为海洋初级生产力的微营养元素,影响海相沉积物中有机质的输入,其在早期成岩阶段与硫化物和磷元素的耦合关系,可以促进或者降低有机质的保存;铁元素在海相沉积物早期成岩过程中可以改变孔隙水的化学性质,影响亚稳定碳酸盐矿物的保存,导致碳酸盐沉积物的溶解与胶结;铁元素在早期成岩过程中赋存状态的改变对海相沉积物的磁学性质有重要的影响,成岩作用可能削弱或者产生二次磁学信号;铁元素在异化铁还原过程中发生同位素分馏,对古海洋中铁的生物地球化学循环过程及古海洋氧化还原状态有重要的指示意义.上述过程与铁元素的赋存状态和有机质分解过程相关,值得进一步深入研究.相关研究对识别地质历史中的缺氧事件、海相烃源岩的形成过程、碳酸盐沉积的模拟以及全球碳循环等一系列重大问题有重要意义.%Iron as one of the highest abundance elements in the crust, plays a very important role in the marine sediment diagenesis. Iron as a nutritive elements in marine primary productivity, affects the input of organic matter in marine sediments; the coupling of iron sulfide and phosphorus can promote or reduce the organic matter burial; During early diagenesis, iron in marine sediments can alter the chemical properties of the pore water, resulting in aragonite grain dissolution, thereby affecting the cementation of carbonate sediments; Diagenetic alterations of iron minerals driven by anaerobic oxidation of organic matter have an important influence on the magnetic properties of marine sediments, producing secondary magnetic signal or weakening them; Isotope fractionation during dis-similatory microbial iron reduction, can indicate the biogeochemical cycle of iron and the redox conditions of ancient oceans

  2. Invisible matter.

    Dolgov, A. D.

    These lectures have been given to particle physicists, mostly experimentalists and very briefly and at a pedestrian level review the problems of dark matter. The content of the lectures is the following: 1. Introduction. 2. Cosmological background. 3. Luminous matter. 4. Primordial nucleosynthesis and the total amount of baryons. 5. Gravitating invisible matter. 6. Baryonic crisis. 7. Inflationary omega. 8. Intermediate summary. 9. Possible forms of dark matter. 10. Structure formation: basic assumptions. 11. Structure formations: basics of the theory. 12. Evolution of perturbations with different forms of dark matter. 13. Conclusion. The presentation and conclusion reflect personal view of the author that a considerable amount of invisible energy in the universe is in the form of vacuum energy (cosmological constant) and possibly in the form of a classical field which adjusts vacuum energy to the value permitted and requested by astronomical data.

  3. Sedimentological features of the surge emitted during the August, 2006 pyroclastic eruption at Tungurahua volcano (Ecuador)

    Douillet, G.; Goldstein, F.; Lavallee, Y.; Hanson, J. B.; Kueppers, U.; Robin, C.; Ramon, P.


    Tungurahua volcano, Ecuador, is a stratovolcano, which began a new eruptive phase in 1999. Notable pyroclastic Density Currents (PDC) were generated in July (VEI 2) and August (VEI 3) 2006 and covered its N and W flanks. PDCs and associated lahars represent a major hazard for 20,000 inhabitants and an hydrological dam. The volcano has been monitored by the Instituto Geofisico of the Escuela Politécnica Nacional of Quito, since 1988. Field work carried out in 2009 provide information on the behavior of the fine-grained fraction of the PDC (i.e., surge) during transport and deposition. We mapped out the sedimentological characteristics of the deposits and distinguished three depositional environments: 1- The core of the deposit, up to several m in thickness, is confined to valleys and consists of poorly-sorted lapilli scoria and blocks (cm to m scale) and a small fraction of ash matrix. Ongoing analysis of the ash matrix will help to understand the link between the main PDC and the associated surge. 2- On ridges and outer margins of valleys, the deposits total a thickness of 10s to 100s cm and consist of fine- to coarse-grain ashes organized in cm-scale beds. Horizontal to cross bed laminations with 10-cm long wavelength prevail. They are typical of deposition under sustained high-energy current, which we associate with the flow of a surge. 3- In the distal part of surge deposits, we observe fine grained surge deposits with a thickness up to ca. 5 m. The characteristic structures are curved crested dunes, 10s of cm high and up to 10s of m long, with dip angles ranging from 15 to 35° and a strongly asymmetric shape. The steepest side tends to be the upslope face. Dunes show mainly a climbing structure, with beds cm in thickness, but some are more complicated, containing cut and fill structures, interpreted as late-stage pulses of energetic turbulence. No displacement dunes were observed in this area. Using the flow direction given by 100s of dunes, we provide

  4. Upper Devonian vertebrate taphonomy and sedimentology from the Klunas fossil site, Tervete Formation, Latvia

    Vasiļkova, J.; Lukševičs, E.; Stinkulis, Ä.¢.; Zupinš, I.


    The deposits of the Tervete Formation, Famennian Stage of Latvia, comprising weakly cemented sandstone and sand intercalated with dolomitic marls, siltstone and clay, have been traditionally interpreted as having formed in a shallow, rather restricted sea with lowered salinity. During seven field seasons the excavations took place in the south-western part of Latvia, at the Klunas site, and resulted in extensive palaeontological and sedimentological data. The taphonomical analysis has been performed, having evaluated the size, sorting, orientation of the fossils, articulation and skeletal preservation as well as the degree of fragmentation and abrasion. The sedimentological analysis involved interpretation of sedimentary structures, palaeocurrent direction reconstruction, grain-size analysis and approximate water depth calculations. The vertebrate assemblage of the Klunas site represents all known taxa of the Sparnene Regional Stage of the Baltic Devonian, comprising placoderms Bothriolepis ornata Eichwald, B. jani Lukševičs, Phyllolepis tolli Vasiliauskas, Dunkleosteus sp. and Chelyophorus sp., sarcopterygians Holoptychius nobilissimus Agassiz, Platycephalichthys skuenicus Vorobyeva, Cryptolepis sp., Conchodus sp., Glyptopomus ? sp., "Strunius" ? sp., and Dipterus sp., as well as an undetermined actinopterygian. Placoderms Bothriolepis ornata and B. jani dominate the assemblage. The fossils are represented in the main by fully disarticulated placoderm plates and plate fragments, sarcopterygian scales and teeth, rarely bones of the head and shoulder girdle, and acanthodian spines and scales. The characteristic feature is the great amount of fragmentary remains several times exceeding the number of intact bones. The horizontal distribution of the bones over the studied area is not homogenous, distinct zones of increased or decreased density of fossils can be traced. Zones of the increased density usually contain many elements of various sizes, whereas zones of the

  5. Residues from coal conversion and utilization: Advanced mineralogical characterization and disposed byproduct diagenesis. [Semiannual report, 1 Mar 1999--31 Aug 1999

    Gregory J. McCarthy; Dean G. Grier


    The goal of the project is to learn more about the phenomenon of coal conversion byproduct (CCB) diagenesis, first described by this group and co-workers at UND EERC seven years ago. CCB diagenesis is a change in the mineralogy that occurs after some CCBs are disposed in a landfill or utilized for a civil engineering application. Regulatory environmental tests and civil engineering tests are typically performed on as-generated CCBs, or on CCBs hydrated and cured for relatively short periods such as 7 or 28 days. One would like to know whether the results of these short-term tests will be valid years later. A change in mineralogy means a gain, loss or chemical redistribution of major, minor and trace elements, and alteration of physical properties. To attain this goal, two objectives were defined: (1) to develop improved methodology for quantitating mineralogy of these complex crystalline phase assemblages, and (2) to investigate the phenomenon of CCB diagenesis further by studying materials recovered from disposal landfills or civil engineering works. Objective 1--Hydrated CCBs are chemically and mineralogically complex, which makes quantitative mineralogy determination by conventional X-ray diffraction unusable or unreliable. The whole-pattern Rietveld quantitative X-ray diffraction (RQXRD) method, however, can overcome many of the problems and seems well suited to improve reliability. Two tasks were defined in the proposal: Task 1--Completion by October 1997. Prepare a reference set of CCBs for use in developing Rietveld QXRD. The reference materials will come primarily from in-house samples of advanced coal technology byproducts. The work will include SEM/EMPA characterization at UND EERC. Task 2--Completion by October 1997. Develop protocols for Rietveld QXRD analysis of CCBs. Make CCB structure data and protocols available on a Website. Determine levels of sensitivity, precision, and accuracy. Objective 2--Five types of CCBs disposed in landfills were studied

  6. Stratigraphy, sedimentology and eruptive mechanisms in the tuff cone of El Golfo (Lanzarote, Canary Islands)

    Pedrazzi, Dario; Martí, Joan; Geyer, Adelina


    The tuff cone of El Golfo on the western coast of Lanzarote (Canary Islands) is a typical hydrovolcanic edifice. Along with other edifices of the same age, it was constructed along a fracture oriented NEE-SWW that coincides with the main structural trend of recent volcanism in this part of the island. We conducted a detailed stratigraphic study of the succession of deposits present in this tuff cone and here interpret them in light of the depositional processes and eruptive dynamics that we were able to infer. The eruptive sequence is represented by a succession of pyroclastic deposits, most of which were emplaced by flow, plus a number of air-fall deposits and ballistic blocks and bombs. We distinguished five different eruptive/depositional stages on the basis of differences in inferred current flow regimes and fragmentation efficiencies represented by the resulting deposits; the different stages may be related to variations in the explosive energy. Eight lithofacies were identified based on sedimentary discontinuities, grain size, components, variations in primary laminations and bedforms. The volcanic edifice was constructed very rapidly around the vent, and this is inferred to have controlled the amount of water that was able to enter the eruption conduit. The sedimentological characteristics of the deposits and the nature and distribution of palagonitic alteration suggest that most of the pyroclastic succession in El Golfo was deposited in a subaerial environment. This type of hydrovolcanic explosive activity is common in the coastal zones of Lanzarote and the other Canary Islands and is one of the main potential hazards that could threaten the human population of this archipelago. Detailed studies of these hydrovolcanic eruptions such as the one we present here can help volcanologists understand the hazards that this type of eruption can generate and provide essential information for undertaking risk assessment in similar volcanic environments.

  7. The Ardross reservoir gridblock analogue: Sedimentology, statistical representivity, and flow upscaling

    Ringrose, P.; Pickup, G.; Jensen, J. [Heriot-Watt Univ., Edinburgh (United Kingdom)] [and others


    We have used a reservoir gridblock-sized outcrop (10m by 100m) of fluvio-deltaic sandstones to evaluate the importance of internal heterogeneity for a hypothetical waterflood displacement process. Using a dataset based on probe permeameter measurements taken from two vertical transacts representing {open_quotes}wells{close_quotes} (5cm sampling) and one {open_quotes}core{close_quotes} sample (exhaustive 1mm-spaced sampling), we evaluate the permeability variability at different lengthscales, the correlation characteristics (structure of the variogram, function), and larger-scale trends. We then relate these statistical measures to the sedimentology. We show how the sediment architecture influences the effective tensor permeability at the lamina and bed scale, and then calculate the effective relative permeability functions for a waterflood. We compare the degree of oil recovery from the formation: (a) using averaged borehole data and no geological structure, and (b) modelling the sediment architecture of the interwell volume using mixed stochastic/deterministic methods. We find that the sediment architecture has an important effect on flow performance, mainly due to bedscale capillary trapping and a consequent reduction in the effective oil mobility. The predicted oil recovery differs by 18% when these small-scale effects are included in the model. Traditional reservoir engineering methods, using averages permeability values, only prove acceptable in high-permeability and low-heterogeneity zones. The main outstanding challenge, represented by this illustration of sub-gridblock scale heterogeneity, is how to capture the relevant geological structure along with the inherent geo-statistical variability. An approach to this problem is proposed.

  8. Sedimentologic Expression of the Cretaceous OAEs in a Tropical Epicontinental Sea

    Silva-Tamayo, J. C.; Eisenhauer, A.


    The acidification and deoxygention of modern oceans are major environmental concerns to the international community. The effects of ocean acidification and deoxigention in the biogeochemical cycles of modern tropical oceans are poorly constrained mainly due to the lack of empirical and quantitative data. The Cretaceous World witnessed several period of potential ocean acidification and deoxygenation, which resulted from the rapid additions of volcanic derived CO2 to the atmosphere. The effects of ocean acidification and deoxygenation on the Cretaceous biogeochemical cycles are evidenced mainly by major global C-isotope anomalies. These anomalies parallel the occurrence of organic rich black shales as well as major decreases in the deposition of shallow marine carbonates worldwide. Here we use detailed C- and Sr- chemostratigraphy as well as published bioestratigraphic information and volcanic zircon U-Pb ages to precisely constrain the geochemical and sedimentologic expression of the Cretaceous OAES along a tropical epicontinental sea, the La Luna Sea. Our multi-pronged approach allows identifying the occurrence of several of the Cretaceous Oceanic Anoxic Events (OAEs) in carbonate units paleogeographically located along the northern most part of the La Luna Sea, i.e. Weissert-OAE-(Palanz and Rosablanca Formations), Faraoni-(Rosablanca Formation), AOE1a-(Paja and Fomeque Formations, Cogollo Group), OAE1c-(Cogollo Group), OAE2-(Cogollo Group), OAE3-(La Luna Formation). These events are preserved in highly euxinic - organic rich "black shales" successions deposited along the deepest part of the seaway at the Middle Magdalena Valley and Cundinamarca Basin; Weiser-OAE-(Lutitas de Macanal Formation), OAE1a-(Paja Formation, Fomeque Formation), OAE1C-(San Gil Formation). Regional changes in depositional settings and sedimentary facies preserving the different Cretaceous OAEs were likely the result of the combined action of regional changes in paleogeography and tectonic

  9. Sedimentological effects of tsunamis, with particular reference to impact-generated and volcanogenic waves

    Bourgeois, Joanne; Wiberg, Patricia L.


    Impulse-generated waves (tsunamis) may be produced, at varying scales and global recurrence intervals (RI), by several processes. Meteorite-water impacts will produce tsunamis, and asteroid-scale impacts with associated mega-tsunamis may occur. A bolide-water impact would undoubtedly produce a major tsunami, whose sedimentological effects should be recognizable. Even a bolide-land impact might trigger major submarine landslides and thus tsunamis. In all posulated scenarios for the K/T boundary event, then, tsunamis are expected, and where to look for them must be determined, and how to distinguish deposits from different tsunamis. Also, because tsunamis decrease in height as they move away from their source, the proximal effects will differ by perhaps orders of magnitude from distal effects. Data on the characteristics of tsunamis at their origin are scarce. Some observations exist for tsunamis generated by thermonuclear explosions and for seismogenic tsunamis, and experimental work was conducted on impact-generated tsunamis. All tsunamis of interest have wave-lengths of 0(100) km and thus behave as shallow-water waves in all ocean depths. Typical wave periods are 0(10 to 100) minutes. The effect of these tsunamis can be estimated in the marine and coastal realm by calculating boundary shear stresses (expressed as U*, the shear velocity). An event layer at the K/T boundary in Texas occurs in mid-shelf muds. Only a large, long-period wave with a wave height of 0(50) m, is deemed sufficient to have produced this layer. Such wave heights imply a nearby volcanic explosion on the scale of Krakatau or larger, or a nearby submarine landslide also of great size, or a bolide-water impact in the ocean.

  10. Sedimentological and Stratigraphic Controls on Natural Fracture Distribution in Wajid Group, SW Saudi Arabia

    Benaafi, Mohammed; Hariri, Mustafa; Abdullatif, Osman; Makkawi, Mohammed; Korvin, Gabor


    The Cambro-Permian Wajid Group, SW Saudi Arabia, is the main groundwater aquifer in Wadi Al-Dawasir and Najran areas. In addition, it has a reservoir potentiality for oil and natural gas in Rub' Al-Khali Basin. Wajid Group divided into four formations, ascending Dibsiyah, Sanamah, Khussyayan and Juwayl. They are mainly sandstone and exposed in an area extend from Wadi Al-Dawasir southward to Najran city and deposited within fluvial, shallow marine and glacial environments. This study aims to investigate the sedimentological and stratigraphic controls on the distribution of natural fractures within Wajid Group outcrops. A scanline sampling method was used to study the natural fracture network within Wajid Group outcrops, where the natural fractures were measured and characterized in 12 locations. Four regional natural fracture sets were observed with mean strikes of 050o, 075o, 345o, and 320o. Seven lithofacies characterized the Wajid Group at these locations and include fine-grained sandstone, coarse to pebbly sandstone, cross-bedded sandstone, massive sandstone, bioturbated sandstone, conglomerate sandstone, and conglomerate lithofacies. We found that the fine-grained and small scale cross-bedded sandstones lithofacies are characterized by high fracture intensity. In contrast, the coarse-grained sandstone and conglomerate lithofacies have low fracture intensity. Therefore, the relative fracture intensity and spacing of natural fractures within Wajid Group in the subsurface can be predicted by using the lithofacies and their depositional environments. In terms of stratigraphy, we found that the bed thickness and the stratigraphic architecture are the main controls on fractures intensity. The outcomes of this study can help to understand and predict the natural fracture distribution within the subsurface fractured sandstone hosting groundwater and hydrocarbon in Wajid and Rub' Al-Khali Basins. Hence, the finding of this study might help to explore and develop the

  11. Sedimentology and significance of an early syn-rift paleovalley, Wadi Tayiba, Suez Rift, Egypt

    Jackson, Christopher Aiden-Lee


    Wadi Tayiba is located along the western margin of the Hammam Faraun fault block, western Sinai, Egypt and is generally thought to contain exposures of the 'type-section' for late pre-rift to early syn-rift stratigraphy associated with the Oligo-Miocene Suez Rift. Previous studies have suggested a complex vertical succession of sedimentary facies characterise the late pre-rift to early syn-rift and imply major and abrupt variations in relative sea-level during this time. Detailed sedimentological and stratigraphic analysis of the Wadi Tayiba type-section presented in this study identifies not only a far simpler vertical facies succession than previously suggested but also the development of a major paleovalley system at the base of the early syn-rift succession. It is suggested that this subtle but significant feature is the cause of the complex vertical facies succession previously interpreted. It is concluded that continuous marine sedimentation and only moderate amplitude variations in relative sea-level occurred during the Eocene to Early Oligocene within at least this part of the Suez Rift. A major relative sea-level fall occurred during the middle Oligocene and a regionally developed erosional surface associated with this event marks the contact between late pre-rift and early syn-rift strata. The results of this study have major implications for sub-regional correlations of late pre-rift to early syn-rift stratigraphic units and resultant palaeogeographic reconstructions of the late pre-rift to early syn-rift period.

  12. Seismic Sedimentology Interpretation Method of Meandering Fluvial Reservoir:From Model to Real Data

    Tao Zhang; Xianguo Zhang; Chengyan Lin; Jingfeng Yu; Shouxiu Zhang


    Reservoir architecture of meandering river deposition is complex and traditional seismic facies interpretation method cannot characterize it when layer thickness is under seismic vertical reso-lution. In this study, a seismic sedimentology interpretation method and workflow for point bar char-acterization is built. Firstly, the influences of seismic frequency and sandstone thickness on seismic re-flection are analyzed by outcrop detection with ground penetrating radar (GPR) and seismic forward modeling. It is found that (1) sandstone thickness can influence seismic reflection of point bar architec-ture. With the increasing of sandstone thickness from 1/4 wavelength (λ) to λ/2, seismic reflection ge-ometries various from ambiguous reflection,“V”type reflection to“X”type reflection;(2) seismic fre-quency can influence reservoirs’ seismic reflection geometry. Seismic events follow inclined lateral ag-gradation surfaces, which is isochronic depositional boundaries, in high frequency seismic data while the events extend along lithologic surfaces, which are level, in low frequency data. Secondly, strata slice interpretation method for thin layer depositional characterization is discussed with seismic forward modeling. Lastly, a method and workflow based on the above study is built which includes seismic fre-quency analysis, 90º phasing, stratal slicing and integrated interpretation of slice and seismic profile. This method is used in real data study in Tiger shoal, the Gulf of Mexico. Two episodes of meandering fluvial deposition is recognized in the study layer. Sandstone of the lower unit, which is formed in low base level stage, distributes limited. Sandstone distribution dimension and channel sinuosity become larger in the upper layer, which is high base level deposition.

  13. A geochemical and sedimentological perspective of the life cycle of Neapolis harbor (Naples, southern Italy)

    Delile, H.; Goiran, J.-P.; Blichert-Toft, J.; Arnaud-Godet, F.; Romano, P.; Bravard, J.-P.


    Since the discovery of the ancient harbor of Naples in 2004 during construction work on an underground railway, geoarchaeological studies undertaken on the archaeological excavation have revealed the main stratigraphic and paleo-environmental levels of the harbor site near the Piazza Municipio. However, knowledge of the dynamics and paleo-environmental changes in the water column of the harbor, as well as the processes of transport and deposition of sediments that led to siltation and infilling of the harbor basin, has been lacking due to the absence of high-resolution data. To fill these gaps, we have undertaken a three-dimensional study (longitudinal, transverse and vertical) of the harbor deposits by carrying out geochemical and sedimentological analyses of four stratigraphic sections of the archaeological excavation. The results show that after a phase of relative calm during the first half of the 1st c. AD, siltation of the harbor progressed exponentially up to the 5th c. AD, when dredging operations were carried out to obtain a water level sufficient for the development of maritime and harbor activities. We attribute this acceleration of siltation to a combination of climatic, anthropic and volcanic factors. Volcanic activity was responsible for a high-energy, tsunami-type event during the eruption of Vesuvius in 79 AD. From the 5th c. AD onwards, the harbor basin of Neapolis does not appear to have been functional as evidenced by its transformation into a lagoon following coastal progradation. The last stage of infilling was the development of a flood-dominated fan delta under the combined influences of climatic cooling in the Early Medieval Cool Period and agro-pastoral activities in the catchment area of the harbor. Several generations of paleo-channels, containing flash flood deposits, as well as sheet wash from sheet floods, are indicative of high environmental instability in this period.

  14. Evolution of Ganges-Brahmaputra western delta plain: Clues from sedimentology and carbon isotopes

    Sarkar, A.; Sengupta, S.; McArthur, J. M.; Ravenscroft, P.; Bera, M. K.; Bhushan, Ravi; Samanta, A.; Agrawal, S.


    Sedimentology, carbon isotope and sequence stratigraphic analysis of subsurface sediments from western part of Ganges-Brahmaputra (GB) delta plain shows that a Late Quaternary marine clay and fluvial channel-overbank sediments of MIS 5 and 3 highstands are traceable below the Holocene strata. During the Last Glacial Maximum (LGM) sea-level lowering of >100 m produced a regional unconformity (type 1), represented by palaeosols and incised valley. C4 vegetation expanded on exposed lowstand surface in an ambient dry glacial climate. At ˜9 ka transgression inundated the lowstand surface pushing the coastline and mangrove front ˜100 km inland. Simultaneous intensification of monsoon and very high sediment discharge (˜4-8 times than modern) caused a rapid aggradation of both floodplain and estuarine valley fill deposits between 8 and 7 ka. The Hoogli River remaining along its present drainage possibly acted as the main conduit for transgression and sediment discharge that was subsequently abandoned. C3 vegetation dominated the delta plain during this time. From 7 ka onward progradation of delta plain started and continued till recent. This period experienced a mixed C3-C4 vegetation with localized mangroves in the mid-Holocene to dominant return of C4 vegetation in the late Holocene period. The study indicates that while the initiation of western part of GB delta occurred at least 1 ka earlier than the global mean delta formation age, the progradation started at ˜7 ka, at least 2 ka earlier than thought before. The terrestrial vegetation change was modulated by changes in depositional environment, specific ecological niches and climate rather than pCO 2.

  15. Coal facies studies in Hungary. A historical review

    Hamor-Vido, Maria [Geological Institute of Hungary, Stefania st.14, Budapest, H-1443 (Hungary)


    The objective of this short summary is to provide an overview on the work of Hungarian geoscientists, who published their results mainly in Hungarian language. The aim of their studies was to understand coal formation and to make reconstruction on the different peat-forming environments. In addition to coal petrographical methods other investigation tools, such as palynology, sedimentology, and organic geochemistry were applied to understand the formation, accumulation and diagenesis of land derived organic matter in different geological realms and environments.

  16. Gaseous Matter

    Angelo, Joseph A


    aseous Matter focuses on the many important discoveries that led to the scientific interpretation of matter in the gaseous state. This new, full-color resource describes the basic characteristics and properties of several important gases, including air, hydrogen, helium, oxygen, and nitrogen. The nature and scope of the science of fluids is discussed in great detail, highlighting the most important scientific principles upon which the field is based. Chapters include:. Gaseous Matter An Initial Perspective. Physical Characteristics of Gases. The Rise of the Science of Gases. Kinetic Theory of

  17. Antimatter Matters



    This video is a teaser-introduction to the Antimatter Matters exhibtion at the Royal Society's Summer Science exhibition July 4-10 2016. The exhibition is jointly organised and hosted by UK members of the ALPHA and LHCb collaborations.

  18. Dirac matter

    Rivasseau, Vincent; Fuchs, Jean-Nöel


    This fifteenth volume of the Poincare Seminar Series, Dirac Matter, describes the surprising resurgence, as a low-energy effective theory of conducting electrons in many condensed matter systems, including graphene and topological insulators, of the famous equation originally invented by P.A.M. Dirac for relativistic quantum mechanics. In five highly pedagogical articles, as befits their origin in lectures to a broad scientific audience, this book explains why Dirac matters. Highlights include the detailed "Graphene and Relativistic Quantum Physics", written by the experimental pioneer, Philip Kim, and devoted to graphene, a form of carbon crystallized in a two-dimensional hexagonal lattice, from its discovery in 2004-2005 by the future Nobel prize winners Kostya Novoselov and Andre Geim to the so-called relativistic quantum Hall effect; the review entitled "Dirac Fermions in Condensed Matter and Beyond", written by two prominent theoreticians, Mark Goerbig and Gilles Montambaux, who consider many other mater...

  19. A 2D hydrodynamic-sedimentological model for gravel-bed rivers. Part I: theory and validation

    Gabriel Kaless; Mario A. Lenzi; Luca Mao


    This paper presents a novel 2D-depth average model especially developed for gravel-bed rivers, named Lican-Leufú (Lican=pebble and Leufu=river, in Mapuche’s language, the native inhabitants of Central Patagonia, Argentina). The model consists of three components: a hydrodynamic, a sedimentological, and a morphological model. The flow of water is described by the depth-averaged Reynolds equations for unsteady, free-surface, shallow water flows. It includes the standard k-e model for turbulence...

  20. Why stratigraphy and sedimentology in shales are important : an example from the Woodford Shale, Permian Basin, west Texas

    Harris, N.B. [Alberta Univ., Edmonton, AB (Canada); Colorado School of Mines, Boulder, CO (United States); Hemmesch, N.T.; Mnich, C.A. [Colorado School of Mines, Boulder, CO (United States). Geology and Geological Engineering; Aoudia, K.; Miskimins, J. [Colorado School of Mines, Boulder, CO (United States). Dept. of Petroleum Engineering


    This presentation explained why stratigraphy and sedimentology in shales are important. The presentation provided an example from the Woodford Shale, Permian Basin, located in western Texas. Several illustrations were presented to demonstrate a stratigraphic sequence in black shale. Other topics that were discussed included geologic settings; paleogeography; silled basins; motivation for rock properties research; and factor analysis results. It was concluded that sequence stratigraphic analyses in black shales requires an integrated, multidisciplinary approach. The presentation showed that third and fourth order stratigraphic cycles are indicated by the repetition of exotic beds whose composition vary regionally. tabs., figs.

  1. Diagenesis of Flint and Porcellanite in the Maastrichtian Chalk at Stevns Klint, Denmark

    Buus Madsen, Heine; Stemmerik, Lars


    was initiated by microbial decomposition of organic matter and took place during periods of low rate of, or even stopped, sedimentation which fixed the redox boundary and the microbial metabolic zones at a specific depth below the sea floor. Biogenic opal-A incorporated in the sediment column below the sea...... of the flint precursor can be controlled by a combination of an abundant biosiliceous source and high microbial activity in the sediments immediately below the seafloor. Flint is therefore likely to reflect deposition in a narrow interval at relatively shallow depths and therefore might be useful in studies...

  2. Constraining coastal change: A morpho-sedimentological concept to infer sea-level oscillation

    Mauz, Barbara; Shen, Zhixiong


    One of the responders to Milankovitch-scale climate changes is sea level which, in turn, is a driver of coastal change. In literature, the sedimentary sequences representing the coastal change are often linked to high sea-level stands, to intermediate sea-level positions or to regressive shorelines. We note apparent contradictions that indicate a lack of concept and inconsistent usage of sea level-related terms. To overcome this, we combine an integrated morpho-sedimentological concept for microtidal, mid-latitudinal coasts with chronologies based on Bayesian statistics. The concept regards the coastal sedimentary system as a depositional complex consisting of shallow-marine, aeolian and alluvial facies. These facies are in juxtaposition and respond simultaneously to external forcing. Bayesian statistics constrains the timing of the sequence based on optical or radiocarbon ages. Here, we present the site Hergla located on the North African coast of the central Mediterranean Sea as a case study to illustrate how the approach helps eliminating contradictions. The site has been cited frequently for confirming the hypothesis of a global two peak sea-level highstand during the last interglacial (MIS 5e). The ~2 km cliff exposure at Hergla was surveyed, mapped, logged and sampled for further describing the sediments and their depositional environment through thin section and Bayesian modelling of optical ages. Using our concept based on sequence stratigraphy tools, the section is interpreted as representing a coastal barrier with two bounding surfaces in the succession. Both surfaces mark the falling sea level of, first, MIS 5e and, second, MIS 5a and hence bound the falling stage system tract of a forced regression. Part of the deposits between the two surfaces are pulled up onto the shoulder of a small rising horst and the associated tectonic event coincided with the MIS 5a sea-level rise enhancing locally the accommodation space for a second foreshore environment. Our

  3. Coral Patch seamount (NE Atlantic) - a sedimentological and megafaunal reconnaissance based on video and hydroacoustic surveys

    Wienberg, C.; Wintersteller, P.; Beuck, L.; Hebbeln, D.


    The present study provides new knowledge about the so far largely unexplored Coral Patch seamount which is located in the NE Atlantic Ocean half-way between the Iberian Peninsula and Madeira. For the first time a detailed hydroacoustic mapping (MBES) in conjunction with video surveys (ROV, camera sled) were performed to describe the sedimentological and biological characteristics of this sub-elliptical ENE-WSW elongated seamount. Video observations were restricted to the southwestern summit area of Coral Patch seamount (water depth: 560-760 m) and revealed that this part of the summit is dominated by exposed hard substrate, whereas soft sediment is just a minor substrate component. Although exposed hardgrounds are dominant for this summit area and, thus, offer suitable habitat for settlement by benthic organisms, the benthic megafauna shows rather scarce occurrence. In particular, scleractinian framework-building cold-water corals are apparently rare with very few isolated and small-sized live occurrences of the species Lophelia pertusa and Madrepora oculata. In contrast, dead coral framework and coral rubble are more frequent pointing to a higher abundance of cold-water corals on Coral Patch during the recent past. This is even supported by the observation of fishing lines that got entangled with rather fresh-looking coral frameworks. Overall, long lines and various species of commercially important fish were frequently observed emphasising the potential of Coral Patch as an important target for fisheries that may have impacted the entire benthic community. Hydroacoustic seabed classification covered the entire summit of Coral Patch and its northern and southern flanks (water depth: 560-2660 m) and revealed extended areas dominated by mixed and soft sediments at the northern flank and to a minor degree at its easternmost summit and southern flank. Nevertheless, these data also predict most of the summit area to be dominated by exposed bedrock which would offer

  4. Coral Patch seamount (NE Atlantic) - a sedimentological and macrofaunal reconnaissance based on video and hydroacoustic surveys

    Wienberg, C.; Wintersteller, P.; Beuck, L.; Hebbeln, D.


    The present study provides new knowledge about the so far largely unexplored Coral Patch seamount which is located in the NE Atlantic Ocean half-way between the Iberian Peninsula and Madeira. For the first time a detailed hydroacoustic mapping (MBES) in conjunction with video surveys (ROV, camera sled) were performed to describe the sedimentological and biological characteristics of this sub-elliptical ENE-WSW elongated seamount. Video observations were restricted to the south-western summit area of Coral Patch seamount (area: ~ 8 km2, water depth: 560-760 m) and revealed that this part of the summit is dominated by exposed hard substrate, whereas soft sediment is just a minor substrate component. Although exposed hardgrounds are dominant for this summit area, and thus, offer suitable habitat for settlement by benthic organisms, the macrofauna shows rather low abundance and diversity. In particular, scleractinian framework-building cold-water corals are apparently rare with very few isolated and small-sized live occurrences of the species Lophelia pertusa and Madrepora oculata. In contrast, dead coral framework and coral rubble are more frequent pointing to a higher abundance of cold-water corals on Coral Patch during the recent past. This is even supported by the observation of fishing lines that got entangled with rather fresh-looking coral frameworks. Overall, long lines and various species of commercially important fish were frequently observed emphasising the potential of Coral Patch as an important target for fisheries that may have impacted the entire benthic community. Hydroacoustic seabed classification covered the entire summit of Coral Patch and its northern and southern flanks (area: 560 km2; water depth: 560-2660 m) and revealed extended areas dominated by mixed and soft sediments at the northern flank and to a minor degree at its easternmost summit and southern flank. Nevertheless, also these data predict most of the summit area to be dominated by

  5. Late Holocene record of sedimentologic and paleooceanographic events in western Guaymas Basin, Gulf of California

    McGann, M.; Paull, C. K.; Herguera, J. C.; Barron, J. A.; Gwiazda, R.; Anderson, K.; Lundsten, E. M.; Edwards, B. D.; Caress, D. W.


    Transects of ≤1.5 m-long vibracores obtained with MBARI's ROV Doc Ricketts reveal late Holocene sedimentologic and paleooceanographic events in western Guaymas Basin, Gulf of California (GOC) (~26.87°N, 111.338°W). Cores were located where layered near-seafloor sediments and subtle bedforms occur in 1793 to 1863 m water depths on the SW flank of the basin using detailed bathymetry and chirp profiles. Color banding was observed in the cores and gamma-density, XRF, grain size, and stable isotope data show that most of the banding is attributed to distal deposition from two turbidities. Distinctive white bands ~4 cm thick are present in three cores dispersed across ~300 m. The white bands are diatom oozes composed primarily of Thalassiothrix longissima as well as lesser abundances of Fragilariopsis doliolus and are probably a result of aggregations of Thalassiothrix-dominated mats that settle through the water column and accumulate on the seafloor. An AMS14C date taken ~3 cm above the white band in one core suggests this event occurred shortly before cal AD 1290±30. The core sites were most likely located beneath an important oceanographic front between nutrient-rich and oligotrophic water masses, probably as the result of well-mixed upper intermediate and surface waters in the mid-GOC and better-stratified tropical waters to the south. This implies the existence of a deeper mixed layer to the N in the mid GOC region most likely controlled by equatorial La Niña events fueled by stronger and more persistent NW winds along the GOC. A substantial reduction in diatom abundance evident by low specimen counts and lack of white bands following this mat-forming event seem to correlate with an abrupt decline in biosiliceous productivity and increases in the abundance of tropical diatoms and silicoflagellates in core MD02-2517 (887 m water depth; western Guaymas Basin slope) at the end of the Medieval Climate Anomaly and transition to the Little Ice Age (~AD 1200-1300).

  6. Sedimentological characteristics of lake sediment of the Lake Jelonek (North Poland)

    Kramkowski, Mateusz; Filbrandt-Czaja, Anna; Ott, Florian; Słowiński, Michał; Tjallingii, Rik; Błaszkiewicz, Mirosław; Brauer, Achim


    Lake Jelonek is located in Northern Poland (53°45'58N, 18°23'30E). The lake is surrounded by forest, covers an area of 19,9 ha and has a maximum depth of 13,8 m. In 2013 and 2014 three overlapping and parallel series of long sediment cores JEL14-A-(1445 cm), JEL14-B-(1430 cm), JEL14-C-(1435 cm) and seven short gravity cores JEL13 (K1-K7) have been recovered from the deepest part of the lake. A continuous composite profile JEL14 covering 1426 cm has been established by correlation based on 28 distinct macroscopic marker layers. The sediment sequence can be divided into 15 (I-XV) lithological units. These units comprise biochemical calcite varves, homogeneous calcite-rich gyttja, homogeneous organic-diatomaceous gyttja, and sandy layers. The chronology established so far is based on 14 AMS 14C dates from terrestrial plant remains and tephrochronology (Askja AD-1875) and covers the interval from the Younger Dryas to present times. Based on the chronology and sedimentological characteristics the composite profile has been correlated to a previous core from which a detailed pollen diagram had been established (Filbrandt-Czaja 2009). Here we present initial results from thin section analyses for two intervals from the new composite record JEL14, (I) the uppermost 0-256 cm and (II) the interval from 768-1296 cm. Intercalated between these two varved interval is a thick section (512 cm) of homogeneous organic-ditomaceous sediments. We present varve micro-facies data in combination with μ-XRF element scanning for comprehensive reconstruction of the sedimentation processes in Lake Jelonek. Preliminary varve counting reveals that the uppermost 256 cm varved sediments comprise ca 925 years (2008-1083 AD), while the lower floating varve interval covers the time period from 1850 - 10500 cal a BP. This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution Analysis -ICLEA- of the Helmholtz Association; grant number VH-VI-415. References

  7. Sedimentological imprint on subseafloor microbial communities in Western Mediterranean Sea Quaternary sediments

    M.-C. Ciobanu


    analyses (CCA showed that the availability of electron acceptors and the quality of electron donors (indicated by age strongly influenced the community structure. In contrast, within the Gulf of Lion core, characterized by a homogeneous lithological structure of upper-slope environment, most detected groups were Bacteroidetes and, to a lesser extent, Betaproteobacteria. At both site, the detection of Betaproteobacteria coincided with increased terrestrial inputs, as confirmed by the geochemical measurements (Si, Sr, Ti and Ca. In the Gulf of Lion, geochemical parameters were also found to drive microbial community composition. Taken together, our data suggest that the palaeoenvironmental history of erosion and deposition recorded in the Western Mediterranean Sea sediments has left its imprint on the sedimentological context for microbial habitability, and then indirectly on structure and composition of the microbial communities during the late Quaternary.

  8. Clear Lake sediments: anthropogenic changes in physical sedimentology and magnetic response.

    Osleger, David A; Zierenberg, Robert A; Suchanek, Thomas H; Stoner, Joseph S; Morgan, Sally; Adam, David P


    We analyzed the sedimentological characteristics and magnetic properties of cores from the three basins of Clear Lake, California, USA, to assess the depositional response to a series of land use changes that occurred in the watershed over the 20th century. Results indicate that distinct and abrupt shifts in particle size, magnetic concentration/mineralogy, and redox conditions occur concurrently with a variety of ecological and chemical changes in lake bed sediments. This coincidence of events occurred around 1927, a datum determined by an abrupt increase in total mercury (Hg) in Clear Lake cores and the known initiation of open-pit Hg mining at the Sulphur Bank Mercury Mine, confirmed by 210Pb dating. Ages below the 1927 horizon were determined by accelerator mass spectrometry on 14C of coarse organic debris. Calculated sedimentation rates below the 1927 datum are approximately 1 mm/yr, whereas rates from 1927 to 2000 are up to an order of magnitude higher, with averages of approximately 3.5-19 mm/yr. In both the Oaks and Upper Arms, the post-1927 co-occurrence of abrupt shifts in magnetic signatures with color differences indicative of changing redox conditions is interpreted to reflect a more oxygenated diagenetic regime and rapid burial of sediment below the depth of sulfate diffusion. Post-1927 in the Oaks Arm, grain size exhibits a gradual coarsening-upward pattern that we attribute to the input of mechanically deposited waste rock related to open-pit mining activities at the mine. In contrast, grain size in the Upper Arm exhibits a gradational fining-upward after 1927 that we interpret as human-induced erosion of fine-grained soils and chemically weathered rocks of the Franciscan Assemblage by heavy earthmoving equipment associated with a road- and home-building boom, exacerbated by stream channel mining and wetlands destruction. The flux of fine-grained sediment into the Upper Arm increased the nutrient load to the lake, and that in turn catalyzed profuse

  9. Sedimentología y paleontología del yacimiento Finimioceno de La Portera (Valencia

    Lacomba, J. I.


    Full Text Available The Sedimentological and Paleontological charactetristics of La Portera Locality have been studied in this work. Four different asociations of facies belonging to several fluvial environments can be distinguished: a Sandstone and conglomerate channel deposits, showing point bar strutuctures; b Red clays of flood plain deposits; e Lacustrine micrite limestones; d Palustrine carbonaceous marls.
    Molluscs are associated to flood plain deposits, where they have more diversity, with associations or terrestrial as well as acuatic species. In the point bars there are acuatic prosobranchs and bivalves, whereas in the lacustrine limestones only molluscs casts are found.
    Mammals are represented by Rodents (Paraethomys anomalus, Equids (Hipparion sp. l, similar to those found in Venta del Moro locality and Hippopotamids (Hexaprotodon crusafonti. The find or a mandible of Hexaprotodon crusafonti permits uS a new definition of the diagnosis of this specie. On basis of these paleontological data the age of La Portera locality has been stalablished as Ventian (NM 13 MEIN'scale.

    En el presente trabajo se estudian las características sedimentológicas y paleontológicas del yacimiento de La Portera (Cuenca del Cabriel. Valencia. Cuatro asociaciones diferentes de facies pertenecientes a distintos subambientes fluviales pueden definirse: a Areniscas y conglomerados de relleno de canal. con estructuras similares a las de los depósitos de barras de meandro. b Arcillas rojas de llanura de inundación. e Calizas micríticas lacustres. d Margas carbonosas pallustres.
    Los moluscos, escasos, aparecen asociados a las facies de llanura de inundación, donde presentan mayor diversidad y mezcla de espcies acuáticas y terrestres; a las barras de meandro con prosobranquios acuáticos y bivalvos, encontrándose en las calizas lacustres sólo moldes. Los mamíferos están representados por un roedor, Paraethomys anomalus

  10. Constraints on the Dynamics of Seabed Pockmarks: an Integrated Sedimentological, Biostratigraphic, Geophysical, Oceanographic and Experimental Approach

    Pau, M.; Hammer, Ø.; Chand, S.; Gisler, G. R.


    Pockmarks are crater-like seabed depressions commonly resulting from focused fluid escape from soft, fine-grained sediments. Typically measuring 20-50 m across with depths of 2-10 m, these features often occur in extensive fields containing hundreds of them per square kilometre. They are prominent hazards for offshore installations such as oil rigs and pipelines, affecting vast areas worldwide. Besides, they represent a major geological source of methane, and their importance has been pointed out as contributors to the global climate variability.Sedimentological and biostratigraphic analyses of sediment cores were coupled with shallow seismic images to investigate the origin and evolution of a pockmark field in the southwestern Barents Sea, an epicontinental sea part of the Arctic Ocean. The pockmarks formed as a result of reduced sedimentation above active gas seeps near the retreating edge of the Barents Sea ice sheet about 15,000 years ago. The seepage is ascribed to climate change-induced dissociation of methane hydrates. These findings strengthen the case that pockmarks, worldwide, recorded the release of massive quantities of methane from the seafloor into the ocean during the last deglaciation. No evidence was found for current upward methane flux, so the pockmarks in the study area appear as inactive seabed features. Field measurements of currents and sediment fluxes in pockmarks in the Oslofjord, Norway, along with an experimental hydrodynamics study, provide insight into the mechanisms responsible for the long-term maintenance of inactive pockmarks. Near-bed currents may control the net sedimentation rate in these depressions by inhibiting the sedimentation from suspended transport. Enhanced turbulence and more intense biological activity suggest that the suspended fines are supported in the water column more easily in the pockmarks than on the surrounding bed, and can be transported away before settling. Moreover, upwelling generated by flow deflection

  11. Sedimentology, sequence-stratigraphy, and geochemical variations in the Mesoproterozoic Nonesuch Formation, northern Wisconsin, USA

    Kingsbury Stewart, Esther; Mauk, Jeffrey L.


    We use core descriptions and portable X-ray fluorescence analyses to identify lithofacies and stratigraphic surfaces for the Mesoproterozoic Nonesuch Formation within the Ashland syncline, Wisconsin. We group lithofacies into facies associations and construct a sequence stratigraphic framework based on lithofacies stacking and stratigraphic surfaces. The fluvial-alluvial facies association (upper Copper Harbor Conglomerate) is overlain across a transgressive surface by the fluctuating-profundal facies association (lower Nonesuch Formation). The fluctuating-profundal facies association comprises a retrogradational sequence set overlain across a maximum flooding surface by an aggradational-progradational sequence set comprising fluctuating-profundal, fluvial-lacustrine, and fluvial-alluvial facies associations (middle Nonesuch through lower Freda Formations). Lithogeochemistry supports sedimentologic and stratigraphic interpretations. Fe/S molar ratios reflect the oxidation state of the lithofacies; values are most depleted above the maximum flooding surface where lithofacies are chemically reduced and are greatest in the chemically oxidized lithofacies. Si/Al and Zr/Al molar ratios reflect the relative abundance of detrital heavy minerals vs. clay minerals; greater values correlate with larger grain size. Vertical facies association stacking records depositional environments that evolved from fluvial and alluvial, to balanced-fill lake, to overfilled lake, and returning to fluvial and alluvial. Elsewhere in the basin, where accommodation was greatest, some volume of fluvial-lacustrine facies is likely present below the transgressive stratigraphic surface. This succession of continental and lake-basin types indicates a predominant tectonic driver of basin evolution. Lithofacies distribution and geochemistry indicate deposition within an asymmetric half-graben bounded on the east by a west-dipping growth fault. While facies assemblages are lacustrine and continental

  12. Sedimentological, Mineralogical and Geochemical Characterization of Sand Dunes in Saudi Arabia

    Benaafi, Mohammed; Abdullatif, Osman


    Sedimentological, mineralogical, morphological and geochemical studies of sand dunes from ten locations in Saudi Arabia were conducted in order to determine the differences between them and to find out the provenance and tectonic setting of these sand dunes. Sixty seven samples were collected from different sand dunes types ranging in morphology from linear, barchans, parabolic to stars dunes. In overall, the sand dunes are fine to coarse grained mean grain size, moderately sorted, near symmetrical skewness with mesokurtic distribution characterized sand dunes in most locations. The sand dunes grains are subrounded in all locations except in the Red sea, Qassim, central Arabia and the eastern province which showed sub-angular grains. The main mineral compositions of studied aeolian sand dunes are quartz, feldspar, calcite, and mica. Quartz is the dominant mineral in locations with significant amount of feldspars and mica in Najran, Red sea and Central Arabia locations. Moreover, calcite is present in Sakaka and NW Empty Quarter (Jafurah). Basement related sand dunes in Najran, Central Arabia and Red sea locations are sub-mature in terms of their mineralogical maturity. Whereas, sand dunes in other locations are texturally mature except those from the Red sea which showed sub-mature sand. The sands are classified as quartz arenite, except in the basement related sand dunes in Najran, central Arabia and the Red sea are ranging from sub-arkose, sub-litharenite and lithraenite. Morphologically, parallel to sub-parallel sand ridges with NE-SW orientation occurred in east and north parts of Empty Quarter (Najran and Jafurah) and NW-SE orientation in Dahna and Nafud deserts in central and north regions of Saudi Arabia. Parabolic sand dunes characterized the Nafud desert (Hail, Sakaka, Tayma locations). Barchans and star sand dunes characterize the Empty Quarter (Jafurah). Major, trace, and rare earth elements studies were carried out to determine the composition

  13. A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides

    Clarke, S. L.; Hubble, T.; Webster, J.; Airey, D.; De Carli, E.; Ferraz, C.; Reimer, P. J.; Boyd, R.; Keene, J.


    Sedimentologic and AMS 14C age data are reported for calcareous hemipelagic mud samples taken from gravity cores collected at sites within, or adjacent to five submarine landslides identified with multibeam bathymetry data on the Nerrang Plateau segment and surrounding canyons of eastern Australia's continental slope (Bribie Bowl, Coolangatta-2, Coolangatta-1, Cudgen and Byron). Sediments are comprised of mixtures of calcareous and terrigenous clay (10-20%), silt (50-65%) and sand (15-40%) and are generally uniform in appearance. Their carbonate contents vary between and 17% and 22% by weight while organic carbon contents are less than 10% by weight. Dating of conformably deposited material identified in ten of the twelve cores indicates a range of sediment accumulation rates between 0.017mka-1 and 0.2 mka-1 which are consistent with previous estimates reported for this area. One slide-adjacent core, and four within-landslide cores present depositional hiatus surfaces located at depths of 0.8 to 2.2 meters below the present-day seafloor and identified by a sharp, colour-change boundary; discernable but small increases in sediment stiffness; and a slight increase in sediment bulk density of 0.1 gcm-3. Distinct gaps in AMS 14C age of at least 20ka are recorded across these boundary surfaces. Examination of sub-bottom profiler records of transects through three of the within-slide core-sites and their nearby landslide scarps available for the Coolangatta-1 and Cudgen slides indicate that: 1) the youngest identifiable sediment layer reflectors upslope of these slides, terminate on and are truncated by slide rupture surfaces; and 2) there is no obvious evidence in the sub-bottom profiles for a post-slide sediment layer draped over or otherwise burying slide ruptures or exposed slide detachment surfaces. This suggests that both these submarine landslides are geologically recent and suggests that the hiatus surfaces identified in Coolangatta-1's and Cudgen's within

  14. Late Cenozoic Uplift of the Chinese South Tian Shan: Insight from Magnetostratigraphy and Sedimentology

    Chen, X.; Chen, H.; Cheng, X. G.; Zhongyue, S.; Lin, X.


    The South Tian Shan in the Central Asia is an intracontinental orogeny reactivated in the late Cenozoic by far-field effect of continuous India-Aisa convergence. However, its uplift time and process remains controversial. Here, Magnetostratigraphic and Sedimentological work in the Cenozoic Tierekesazi Profile in the South Tian Shan foreland was taken to figure out these problems. The Cenozoic sediment reveals a section of generally upwardly increasing particle sizes triggered by uplift of Tian Shan. Based on increasing particle size and water power, the Cenozoic succession could be divided into four lithofacies: (i) Paleogene marine lithofacies from the Paleogene Aertashi to Eocene-Oligocene Bashibulake Formation, (ii) lacustrine to fluvial (plain) lithofacies from the early Miocene Keziluoyi Formation to the middle of middle Miocene Pakabulake Formations, (iii) alluvial sand-gravel sheet lithofacies in the upperpart of middle Miocene Pakabulake Formation, and (iv) conglomerate lithofacies from the Neogene Atushi to Quaternary Xiyu Formation. Our magnetostratigraphic results, combined with biostratigraphic correlations, provide the chronologic constraints for each lithofacies and also the sediment accumulation rates (SAR). These results indicate lithofacies (i) aged ca. 65-34 Ma, lithofacies (ii) aged ca. 22.1-12 Ma, lithofacies (iii) aged ca. 12-5.2 Ma, and lithofacies (iv) aged ca. 5.2 Ma-present (?), with SARs increasing from lithofacies (i) to (iv). Regional correlation of SAR from foreland of South Tian Shan has suggested a linkage of the sedimentary event to the tectonic activity along South Tian Shan. We propose that the earliest Miocene event may represent the initial response of the far-field effect of Indian-Eurasian convergence, but more directly and likely marks the initial underthrusting of the Tarim block beneath the South Tian Shan. The mid-Miocene and Mio-Pliocene boundary events have different structural expression in the opposite regions east and

  15. Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania between 640 ka and present day

    A. Francke


    Full Text Available Lake Ohrid (FYROM, Albania is thought to be more than 1.2 million years old and hosts more than 200 endemic species. As a target of the International Continental Scientific Drilling Program (ICDP, a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO project in 2013. Here, we present lithological, sedimentological, and (bio-geochemical data from the upper 247.8 m of the overall 569 m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on nine tephra layers (1st order tie points, and on tuning of biogeochemical proxy data to orbital parameters (2nd order tie points and to the global benthic isotope stack LR04 (3rd order tie points, respectively, the analyzed sediment sequence covers the last 640 ka. The DEEP site sediment succession consists of hemipelagic sediments, which are interspersed by several tephra layers and infrequent, thin (< 5 cm mass wasting deposits. The hemipelagic sediments can be classified into three different lithotypes. Lithotype 1 and 2 deposits comprise calcareous and slightly calcareous silty clay and are predominantly attributed to interglacial periods with high primary productivity in the lake during summer and reduced mixing during winter. The data suggest that high ion and nutrient concentrations in the lake water promoted calcite precipitation and diatom growth in the epilmnion in during MIS15, 13, and 5. Following a strong primary productivity, highest interglacial temperatures can be reported for MIS11 and 5, whereas MIS15, 13, 9, and 7 were comparable cooler. Lithotype 3 deposits consist of clastic, silty clayey material and predominantly represent glacial periods with low primary productivity during summer and longer and intensified mixing during winter. The data imply that most severe glacial conditions at Lake Ohrid persisted during MIS16, 12, 10, and 6

  16. Systems tracts sedimentology in the lagoon of Mayotte associated with the Holocene transgression

    Zinke, J.; Reijmer, J. J. G.; Thomassin, B. A.


    Twelve gravity cores from various settings within the Mayotte barrier reef-lagoon complex were studied to determine the sedimentology of the sequence stratigraphic systems tracts that formed during the Holocene transgression. Our studies focussed on the determination of physical, chemical, mineralogical and biological parameters of the sediments from specific systems tracts. These parameters determine the thickness and facies of each systems tracts and are controlled by the rate and amplitude of sea-level rise, lagoonal topography and environmental changes. The lowstand systems tract (LST) (before 11.5 ka BP) comprises ferralitic or organic-rich paleosoils in the proximal and middle lagoon and karstified Pleistocene reefal carbonates in the distal lagoon. The transgressive systems tract (TST) (11.5-7 ka BP) consists of a lower terrigenous and an upper mixed terrigenous-carbonate or carbonate-dominated unit. Locally, mangrove muds were deposited. The highstand systems tract (HST) can be divided into an early highstand (eHST) (7-1 ka BP) and a late highstand systems tract (lHST) (after 1 ka BP). In the proximal lagoonal wedge, the early highstand systems tract consists of terrigenous or mixed terrigenous-carbonate muds to sandy muds. In the middle lagoon, it shows carbonate mud to sandy mud and carbonate gravel to reefal carbonates in the distal lagoons. Terrigenous muds dominate the late highstand systems tract in the proximal lagoonal wedge. In the mid-lagoonal plain, mixed terrigenous-carbonate or carbonate mud to sandy mud dominates, while carbonate gravel to reefal carbonate prevails in the distal lagoon. For the last 9 ka, sedimentation in the lagoon of Mayotte has been spatially divided into a proximal terrigenous and a distal, carbonate-dominated province. Maximum carbonate concentrations between 4 and 1 ka BP coincide with the time of maximum solar insolation. After 1 ka BP, a general decrease in carbonate concentrations can be observed. This coincides with

  17. Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 637 ka and the present

    Francke, Alexander; Wagner, Bernd; Just, Janna; Leicher, Niklas; Gromig, Raphael; Baumgarten, Henrike; Vogel, Hendrik; Lacey, Jack H.; Sadori, Laura; Wonik, Thomas; Leng, Melanie J.; Zanchetta, Giovanni; Sulpizio, Roberto; Giaccio, Biagio


    Lake Ohrid (Macedonia, Albania) is thought to be more than 1.2 million years old and host more than 300 endemic species. As a target of the International Continental scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8 m composite depth of the overall 569 m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on 11 tephra layers (first-order tie points) and on tuning of bio-geochemical proxy data to orbital parameters (second-order tie points), the analyzed sediment sequence covers the last 637 kyr. The DEEP site sediment succession consists of hemipelagic sediments, which are interspersed by several tephra layers and infrequent, thin (< 5 cm) mass wasting deposits. The hemipelagic sediments can be classified into three different lithotypes. Lithotype 1 and 2 deposits comprise calcareous and slightly calcareous silty clay and are predominantly attributed to interglacial periods with high primary productivity in the lake during summer and reduced mixing during winter. The data suggest that high ion and nutrient concentrations in the lake water promoted calcite precipitation and diatom growth in the epilimnion during MIS15, 13, and 5. Following a strong primary productivity, highest interglacial temperatures can be reported for marine isotope stages (MIS) 11 and 5, whereas MIS15, 13, 9, and 7 were comparably cooler. Lithotype 3 deposits consist of clastic, silty clayey material and predominantly represent glacial periods with low primary productivity during summer and longer and intensified mixing during winter. The data imply that the most severe glacial conditions at Lake Ohrid persisted during MIS16, 12, 10, and 6, whereas somewhat warmer temperatures can be

  18. Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 640 ka and present day

    Francke, A.; Wagner, B.; Just, J.; Leicher, N.; Gromig, R.; Baumgarten, H.; Vogel, H.; Lacey, J. H.; Sadori, L.; Wonik, T.; Leng, M. J.; Zanchetta, G.; Sulpizio, R.; Giaccio, B.


    Lake Ohrid (FYROM, Albania) is thought to be more than 1.2 million years old and hosts more than 200 endemic species. As a target of the International Continental Scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8 m of the overall 569 m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on nine tephra layers (1st order tie points), and on tuning of biogeochemical proxy data to orbital parameters (2nd order tie points) and to the global benthic isotope stack LR04 (3rd order tie points), respectively, the analyzed sediment sequence covers the last 640 ka. The DEEP site sediment succession consists of hemipelagic sediments, which are interspersed by several tephra layers and infrequent, thin (< 5 cm) mass wasting deposits. The hemipelagic sediments can be classified into three different lithotypes. Lithotype 1 and 2 deposits comprise calcareous and slightly calcareous silty clay and are predominantly attributed to interglacial periods with high primary productivity in the lake during summer and reduced mixing during winter. The data suggest that high ion and nutrient concentrations in the lake water promoted calcite precipitation and diatom growth in the epilmnion in during MIS15, 13, and 5. Following a strong primary productivity, highest interglacial temperatures can be reported for MIS11 and 5, whereas MIS15, 13, 9, and 7 were comparable cooler. Lithotype 3 deposits consist of clastic, silty clayey material and predominantly represent glacial periods with low primary productivity during summer and longer and intensified mixing during winter. The data imply that most severe glacial conditions at Lake Ohrid persisted during MIS16, 12, 10, and 6 whereas

  19. The Late Pleistocene Duoi U'Oi cave in northern Vietnam: palaeontology, sedimentology, taphonomy and palaeoenvironments

    Bacon, Anne-Marie; Demeter, F.; Duringer, P.; Helm, C.; Bano, M.; Vu, The Long; Kim Thuy, Nguyen Thi; Antoine, P.-O.; Thi Mai, Bui; Huong, Nguyen Thi Mai; Dodo, Y.; Chabaux, F.; Rihs, S.


    This paper describes new fossil materials recovered at the Duoi U'Oi site, in December 2003, by a Vietnamese-French-Japanese team. The Duoi U'Oi cave is located in Man Duc village, 25 km of Hoà Binh city in northern Vietnam. It belongs to a karstic network developed in a dark grey micritic marine limestone dated from the Lower to the Middle Triassic. The sedimentary fill produced a rich mammalian fauna, essentially composed of isolated teeth of middle- to large-sized mammals (Artiodactyla, Perissodactyla, Proboscidea, Carnivora, Rodentia, Primates), and characteristic of Late Pleistocene. The results of the Duoi U'Oi fieldwork are of great interest for the following reasons: (1) the biochronological age of the fauna is consistent with 230Th/ 234U/ 238U dating from the calcitic floors (66±3 ka). The Duoi U'Oi fauna is thus the oldest well-dated modern fauna known for the Southeast Asian mainland; (2) in terms of sedimentology, the analysis of the formation of the fossiliferous breccia and that of the processes of deposits shows a close relation between the karstic deposits inside the cave and the deposits in the alluvial terraces. The observation of three levels of alluvial terraces associated with three caves situated at 62, 10 and 3 m above the present alluvial plain suggests that exokarstic and endokarstic sediments evolved together; (3) in terms of palaeobiogeography, Duoi U'Oi is the continental fauna showing the strongest resemblance with the Late Pleistocene faunas from Indonesian islands (Punung, Gunung Dawung, Lida Ajer, Sibrambang and Djambu caves); this implies that, at the time of Duoi U'Oi, ca 70 ka, the Sundaland was mainly characterised by faunas of modern aspect; (4) the analysis of major taphonomic factors that led to the mammal assemblage reveals a combination of selective agents (selective role of predators and porcupines, selective destruction of age classes for some species, selective preservation of fossils due to the deposition processes in

  20. Chemical diagenesis, porosity reduction, and rock strength, IODP Site U1480: Influences on great earthquakes at shallow depths

    Song, Insun; Milliken, Kitty; Dugan, Brandon; Bourlange, Sylvain; Colson, Tobias; Frederik, Marina; Jeppson, Tamara; Kuranaga, Mebae; Nair, Nisha; Henstock, Timothy


    mechanical compaction. The rock strengthening by mechanical compaction is dependent on effective stress, and does not facilitate storage of a large amount of elastic energy at shallow depth. However, chemical diagenesis (cementation) can lead to high strength that does not necessarily arise directly from burial. This chemical diagenesis potentially influences sediment strengthening that localizes great earthquakes at shallow depths.

  1. Study on the application of seismic sedimentology in a stratigraphic-lithologic reservoir in central Junggar Basin

    Yu, Yixin; Xia, Zhongmou


    This paper discusses the research idea of description for stratigraphic-lithologic reservoir based on seismic sedimentology methods. The sandstone reservoir of Jurrassic XiShanyao Formation in Junggar Basin is studied according to the theory and approaches of seismic sedimentology. By making full use of borehole data, the technologies of layer correlation based on the stratigraphic sequence framework, the forward seismic modeling, the stratal slicing and lithologic inversion are applied. It describes the range of denudation line, the distribution characteristics of sedimentary facies of the strata, the vertical and horizontal distribution of sand bodies and the favourable oil-gas bearing prospective area. The results shows that study area are dominated braided delta deposition including underwater distributary channel and distributary bay microfacies, the nip-out lines of the formation are northeast to southwest from north to south, the second Middle Jurassic sand body is the most widely distributed one among three sand bodies, the prospective oil-gas bearing area located in the south part and around the YG2 well area. The study result is effective on the practice of exploration in study area.

  2. Selected contributions from the 9th International Conference on Tidal Sedimentology, November 2015, Puerto Madryn, Patagonia, Argentina: an introduction

    Scasso, Roberto A.; Cuitiño, José I.


    This special issue of Geo-Marine Letters presents selected contributions from the 9th International Conference on Tidal Sedimentology held on 17-19 November 2015 in Puerto Madryn, Chubut Province, Patagonia, Argentina. The guest editors are the conference organizers Roberto A. Scasso and José I. Cuitiño. Gerardo M. Perillo was the head of the Scientific Committee. The conferences on tidal sedimentology have been traditionally held every 4 years. However, only 3 years separated the last conference held in Caen (France, 2012) from this conference. Increasing numbers of contributions and the growing interest in tidal sedimentation have been the reasons for shortening the inter-conference period. The 2015 conference served as a discussion forum focusing on advances in modern and ancient tidal sedimentation at different locations worldwide. The papers presented in this Special Issue provide a selective view of the latest research results, the main topics dealing with tidal hydrodynamics and sediment transport, tidal coastal morphodynamics, modern and ancient tidal sedimentation, geotechnical processes in tidal environments, and tidal basins, facies and reservoirs.

  3. Sedimentological dynamics of the Orlovat loess-paleosol sequence (Northern Serbia) show both local and regional paleoenvironmental fluctuations

    Obreht, Igor; Zeeden, Christian; Eckmeier, Eileen; Schulte, Philipp; Hambach, Ulrich; Timar-Gabor, Alida; Lehmkuhl, Frank


    The last glacial cycle as recorded in the Orlovat loess section (Northern Serbia) gives insight into both local and regional paleoenvironmental conditions. The Orlovat section is a unique section in the Carpathian Basin and it is characterized by irregularities in sedimentology, magnetic susceptibility, geochemistry and other paleoproxies. Therefore the local conditions need to be understood before making claims on a regional scale. Especially the grain size distribution indicates that the Orlovat site was influenced by specific paleoenvironmental conditions. Relatively coarse grained sand was delivered during interglacials, probably from the Deliblato sands by the Košava wind. However, commonly applied methods such as grain size and rock magnetic investigations could not explain the unique situation during the MIS 3, where a paleosol is missing. Therefore, for the first time in the studies of the region, we applied high resolution X-ray fluorescence analysis to trace the changing source areas of sediment material during the Last Glacial. These changes in the provenance of the sediment might be associated with stronger river activities and erosion. This study highlights the importance of a sedimentological understanding for a reliable paleoenvironmental evaluation.

  4. Sedimentological and diagenetic controls on Cambro-Ordovician reservoir quality in the southern Hassi Messaoud area (Saharan Platform, Algeria)

    Djarnia, M.R.; Fekirine, B. [CRD-Sonatrach, Boumerdes (Algeria)


    The Cambro-Ordovician reservoirs of the Hassi-Messaoud area comprise quartzitic sandstones, which rest unconformably on granitic basement and are capped by the Hercynian unconformity. Two sequence stratigraphic cycles are identified: a lower cycle of lowstand, transgressive and highstand deposits, and an upper cycle in which only lowstand deposits are preserved below the Hercynian unconformity. Petrographic and scanning electron microscope studies were conducted in two wells in the southern Hassi Messaoud area on five sandstone units. Reservoir quality is found to bear a strong relationship to clay content and mineralogy. Comparative diagenetic studies carried out within both the oil-bearing and the water-bearing parts of the reservoirs have determined that all the secondary processes occurred under freely operating diagenesis, pre-dating oil emplacement in the structure. (author)

  5. [Discussion on diagenesis of Xilingang pluton-constrained by X-ray Fluorescence spectroscopy, plasma mass spectrometry and Raman spectroscopy].

    Tang, Yu-Kun; Chen, Guo-Neng; Zhang, Ke; Huang, Hai-Hua


    The results on Xilingang pluton, mainly consisting of red beds, granites containing numerous debris of red beds and granites, obtained by X-ray fluorescence spectroscopy, plasma mass spectrometry and Raman spectroscopy show: (1) Xilingang pluton from red beds, granites containing numerous debris of red beds to granites has obvious characteristics of decreasing silicon and alkali content, and rising ignition loss, dark mineral content and oxidation index; (2) Chondrite-normalized REE distribution curves and primitive mantle-normalized spider diagram for trace elements of redbed, granites containing numerous debris of red beds and granites have a good consistency, the distribution characteristics of elements are similar to Nanling transformation-type granite; (3) The value of Raman spectrogram characteristic peak of quartz crystal in Xilingang granite decreased from the center of quartz crystal, and FWHM is steady. According to the above, the authors believe that Xilingang granite formed was related to in-situ melting of red beds and underlying strata and magma consolidation. Volatile components were discharged continuously, and oxidation index decreased gradually in the melting process. In the process of diagenesis, the top of pluton tend to be an ongoing silicon and alkali increase, while TFeO and MgO continue to migrate to bottom, and crystallization environment is a relatively closed and steady system.

  6. Dissolved organic matter in anoxic pore waters from Mangrove Lake, Bermuda

    Orem, W.H.; Hatcher, P.G.; Spiker, E. C.; Szeverenyi, N.M.; Maciel, G.E.


    Dissolved organic matter and dissolved inorganic chemical species in anoxic pore water from Mangrove Lake, Bermuda sediments were studied to evaluate the role of pore water in the early diagenesis of organic matter. Dissolved sulphate, titration alkalinity, phosphate, and ammonia concentration versus depth profiles were typical of many nearshore clastic sediments and indicated sulphate reduction in the upper 100 cm of sediment. The dissolved organic matter in the pore water was made up predominantly of large molecules, was concentrated from large quantities of pore water by using ultrafiltration and was extensively tudied by using elemental and stable carbon isotope analysis and high-resolution, solid state 13C nuclear magnetic resonance and infrared spectroscopy. The results indicate that this material has a predominantly polysaccharide-like structure and in addition contains a large amount of oxygen-containing functional groups (e.g., carboxyl groups). The 13C nulcear magnetic resonance spectra of the high-molecular-weight dissolved organic matter resemble those of the organic matter in the surface sediments of Mangrove Lake. We propose that this high-molecular-weight organic matter in pore waters represents the partially degraded, labile organic components of the sedimentary organic matter and that pore waters serve as a conduit for removal of these labile organic components from the sediments. The more refractory components are, thus, selectively preserved in the sediments as humic substances (primarily humin). ?? 1986.

  7. Sedimentology and sequence stratigraphy of Lower Shihezi Formation in Shenguhao area, northern Ordos basin, China

    Chen, Lin; Lu, Yongchao; Lin, Zi


    The structural location of Shenguhao area locates at the transition zone of Yimeng uplift and Yishan slope of northern Ordos basin, China. The study area is in erosion condition until Late Carboniferous and has deposited Taiyuan Formation (C2t), Shanxi Formation (P1s), Lower Shihezi Formation (P1x), Upper Shihezi Formation (P2s) and Shiqianfeng Formation (P2sh) in succession during Late Paleozoic, which mainly develops transition facies and alluvial plain facies. The fluvial sandstone of Lower Shihezi Formation is the major target layer of gas exploration and development in this area. This study is based on the interpretation of 38 wells and 113 sesmic reflection profiles. Three significant lithofacies were identified with sedimentological analysis of cores from the Shenguhao area: fluvial conglomerates, fluvial sandstone and floodplain mudstone, which represent fluvial depositional environment. Based on sequence stratigraphy methodology, well log patterns and lithofacies analysis, Lower Shihezi Formation can be divided into four depositional sequence cycles (1-4) bounded by fluvial scouring erosional surfaces. Each sequence succession shows the trend of base level rising and overall performs fining-upward feature, which characterized by coarsening-upward lower to upper fluvial sandstone and floodplain mudstone. In ascending order, sequence 1 records the transition from the underlying braided river delta plain fine-grained sediments of Shanxi Formation into the overlying fluvial sandstone of Lower Shihezi Formation and develops scouring erosional unconformity at the base, representing a regression. Sequence 1 consists of a package of progradting thick layer of amalgamated fluvial sandstone at the lower part passing into aggrading thin layer of floodplain mudstone at the upper part, suggesting that accommodation growing rate is gradually greater than deposition supply rate under the background of base level gradual increase. Sequence 2 and 3 record similar

  8. Sedimentology and arsenic pollution in the Bengal Basin: insight into arsenic occurrence and subsurface geology.

    Hills, Andrew; McArthur, John


    The Bengal delta system is a geologically recent feature overlying a deeply incised palaeo-surface formed during the Last Glacial Maximum. This surface is a series of terraces and valleys created by river incision (Goodbred & Kuehl 2003). The terraces were weathered, forming a thin, indurated laterite deposit (Goodbred & Kuehl 2000) at depths greater than 50 m. McArthur et al. (2008) define this as a palaeosol and have identified it at depths greater than 30 m though out Bangladesh and West Bengal. It has been observed that arsenic concentrations at these sites are lower than the rest of the delta. It has been assumed that the surface morphology at sites where there is a palaeosol are similar and can therefore be characterised by remote sensing, in the form of Google Earth images. Sites were selected in Bangladesh and West Bengal, from work by McArthur et al. (2011); Hoque et al. (2012), where groundwater chemistry and sedimentology data are available making it possible to determine if the subsurface is a palaeo-channel or palaeo-interfluve. Arsenic concentration data have been inputted into Google Earth and the palaeo-channels marked where the arsenic concentration is greater than 10 µg/L, and palaeo-interfluves where arsenic concentration is less than 10 µg/L. The surface morphologies in these domains have been examined for similarities, and it was shown that avulsion scars and abandoned river channels are found where arsenic concentrations are greater than 10 µg/L. Conversely the surrounding areas that are devoid of channel scars have arsenic concentrations less than 10 µg/L. Using the correlation between avulsion features being representative of palaeo-channels and high arsenic concentrations, sites were selected that had a similar surface morphology to the type localities. A comparison of these images and arsenic concentrations showed that the postulate is valid for over 80 percent of cases. Where this is not valid, this could indicate that the subsurface

  9. Sedimentology of cores recovered from the Canada Basin of the Arctic Ocean

    Edwards, B. D.; Saint-Ange, F.; Pohlman, J.; Higgins, J.; Mosher, D. C.; Lorenson, T. D.; Hart, P.


    gravelly sandy clay interpreted to be altered hydrothermally. Successions of IRD layers create a thinly- to medium-bedded sequence throughout the lower section. Site 4 (3700 m water depth; central Canada Basin): This core recovered 3.4 m of sediment typified by decimeter-thick sequences of stacked graded beds with erosional basal contacts (Bouma sequences) characteristic of turbidite deposition. Site 5 (2081 m water depth; continental slope west of the Canadian archipelago): This core recovered 4.96 m of sediment of which the upper 2 m is silty clay to clayey silt with dispersed sand and granules. This upper section has an irregular, sharp basal contact with an underlying 16-cm-thick clast-supported massive gravel. The gravel has a scoured basal contact and overlies a monotonous gray clayey silt containing dispersed granules of IRD. Sparse and poorly preserved fauna throughout all the cores make age determination difficult; however, given the paucity of sediment cores in the Arctic Ocean, these samples provide vital geophysical groundtruth and sedimentological information about the basin.

  10. Time matters

    Andreasen, Karen Egedal; Rasmussen, Annette

    During 2011 national standardised testing within areas such as reading, mathematics, science etc. has been introduced in Danish compulsory school by the Educational Ministry as something new. The inspirations behind this initiative are both the international comparative educational studies such a...... the introduction of standardised testing meens to pupils perception of school matters, selfperception etc. In my analysis and discussion I will among others draw on Basil Bernsteins theoretical...

  11. Sedimentological evolution of the Givetian-Eifelian (F3) sand bar of the West Alrar field, Illizi Basin, Algeria

    Chaouchi, R. [National Institute for Hydrocarbons and Chemistry, Boumerdes (Algeria); Malla, M.S.; Kechou, F. [Sonatrach, Algiers (Algeria). Exploration Div.


    Commercial accumulations of hydrocarbons depend on several factors, among which sedimentological conditions are of prime importance. Such sedimentatological factors are of particular importance in controlling both entrapment and reservoir quality in the western part of the Alrar field, within the F3 sandstone reservoir of Givetian-Eifelian age. Recent well results have shown facies and reservoir quality distribution to be more complex and generally more favourable than previously predicted. A series of tidally influenced litoral bars are now believed to have existed in the Alrar area at the time of deposition of the reservoir, these being elongated in a NW-SE direction in the West Alrar area, with an interbar area in the vicinity of well DZ-1. The highest reservoir quality is largely confined to this bar facies and understanding its distribution is therefore vital to locating development wells. (author)

  12. Isotopic and sedimentological clues to productivity change in Late Riphean Sea: A case study from two intracratonic basins of India

    P P Chakraborty; A Sarkar; S K Bhattacharya; P Sanyal


    Enriched 13C/12 ratios with 13C ∼3‰ (w.r.t PDB) of two Late Riphean (∼700-610Ma) intracratonic carbonate successions viz., Bhander Limestone of Vindhyan Basin and Raipur Limestone of Chattisgarh Basin suggest higher organic productivity during this period. This view is supported by sedimentological evidence of higher biohermal growth and consequent increase in depositional relief in the low gradient ramp settings inferred for these basins. Oxygen isotope analysis of these carbonates show distinct segregation between enriched deeper water carbonate mudstone and depleted shallow water stromatolite facies that received fresh water influx. This shows that facies-specific analyses can be useful in understanding the depositional setting of these sediments.

  13. Sedimentological Analysis of Well Data by the Example of the Dagi Horizon of the Northeastern Shelf of Sakhalin Island

    V.V. Rybal’chenko


    Full Text Available Well logging methods provide important data on data on sedimentary structures, genesis of sedi-ments, and relations of the facies in sedimentary basins. This paper demonstrates the potential of sedimen-tological interpretation when applied to data from the formation microimagers (FMI. The study is based on the results of the joint project on integrated analysis of wellbore images and core samples of the Neo-gene deposits of the northeastern shelf of Sakhalin Island between “Gazprom”, “Gazprom geologora-zvedka”, and Schlumberger Company. The image log represents 300 m of the well section, when 95 m are characterized by the core. The study included detailed matching of the core data with open hole logs as adjusted for core recovery, lithological description of the well section, structural and textural interpreta-tion of the images, facies analysis, orientation of the paleocurrent direction, and reconstruction of the depositional environments.

  14. Interstitial solutions and diagenesis in deeply buried marine sediments: results from the Deep Sea Drilling Project

    Sayles, F.L.; Manheim, F. T.


    Through the Deep Sea Drilling Project samples of interstitial solutions of deeply buried marine sediments throughout the World Ocean have been obtained and analyzed. The studies have shown that in all but the most slowly deposited sediments pore fluids exhibit changes in composition upon burial. These changes can be grouped into a few consistent patterns that facilitate identification of the diagenetic reactions occurring in the sediments. Pelagic clays and slowly deposited (recrystallization of biogenic calcite and the substitution of Mg2+ for Ca2+ during this reaction. The Ca-Mg-carbonate formed is most likely a dolomitic phase. A related but more complex pattern is found in carbonate sediments deposited at somewhat greater rates. Ca2+ and Sr2+ enrichment is again characteristic, but Mg2+ losses exceed Ca2+ gains with the excess being balanced by SO4post staggered2- losses. The data indicate that the reactions are similar to those noted above, except that the Ca2+ released is not kept in solution but is precipitated by the HCO3post staggered- produced in SO4post staggered2- reduction. In both these types of pore waters Na+ is usually conservative, but K+ depletions are frequent. In several partly consolidated sediment sections approaching igneous basement contact, very marked interstitial calcium enrichment has been found (to 5.5 g/kg). These phenomena are marked by pronounced depletion in Na+, Si and CO2, and slight enhancement in Cl-. The changes are attributed to exchange of Na+ for Ca2+ in silicate minerals forming from submarine weathering of igneous rocks such as basalts. Water is also consumed in these reactions, accounting for minor increases in total interstitial salinity. Terrigenous, organic-rich sediments deposited rapidly along continental margins also exhibit significant evidences of alteration. Microbial reactions involving organic matter lead to complete removal of SO4post staggered2-, strong HCO3post staggered- enrichment, formation of NH4post

  15. Diagenesis and reservoir quality of the Lower Cretaceous Quantou Formation tight sandstones in the southern Songliao Basin, China

    Xi, Kelai; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Bjørlykke, Knut; Haile, Beyene Girma; Zheng, Lijing; Hellevang, Helge


    The Lower Cretaceous Quantou Formation in the southern Songliao Basin is the typical tight oil sandstone in China. For effective exploration, appraisal and production from such a tight oil sandstone, the diagenesis and reservoir quality must be thoroughly studied first. The tight oil sandstone has been examined by a variety of methods, including core and thin section observation, XRD, SEM, CL, fluorescence, electron probing analysis, fluid inclusion and isotope testing and quantitative determination of reservoir properties. The sandstones are mostly lithic arkoses and feldspathic litharenites with fine to medium grain size and moderate to good sorting. The sandstones are dominated by feldspar, quartz, and volcanic rock fragments showing various stages of disintegration. The reservoir properties are quite poor, with low porosity (average 8.54%) and permeability (average 0.493 mD), small pore-throat radius (average 0.206 μm) and high displacement pressure (mostly higher than 1 MPa). The tight sandstone reservoirs have undergone significant diagenetic alterations such as compaction, feldspar dissolution, quartz cementation, carbonate cementation (mainly ferrocalcite and ankerite) and clay mineral alteration. As to the onset time, the oil emplacement was prior to the carbonate cementation but posterior to the quartz cementation and feldspar dissolution. The smectite to illite reaction and pressure solution at stylolites provide a most important silica sources for quartz cementation. Carbonate cements increase towards interbedded mudstones. Mechanical compaction has played a more important role than cementation in destroying the reservoir quality of the K1q4 sandstone reservoirs. Mixed-layer illite/smectite and illite reduced the porosity and permeability significantly, while chlorite preserved the porosity and permeability since it tends to be oil wet so that later carbonate cementation can be inhibited to some extent. It is likely that the oil emplacement occurred

  16. Using in situ REE analysis to study the origin and diagenesis of dolomite of Lower Paleozoic, Tarim Basin

    WANG XiaoLin; JIN ZhiJun; HU WenXuan; ZHANG JunTao; QIAN YiXiong; ZHU JingQuan; LI Qing


    In situ REE concentrations of various dolomites from Tarim Basin were obtained by LA-ICP-MS analysis, and the data were normalized to standard seawater (Seawater Normalized=SWN). Most of the samples have a ΣREE range of less than 20 ppm. All samples show similar REE distributions with heavy REE depletion, and positive Ce anomaly, which indicates that they have the same dolomitization fluids (seawater). According to the origin and diagenetic process of dolomite, two types of dolomite are de-termined and described as follows: 1) syndepositional dolomite, with the highest REE concentrations (more than 20 ppm), the cores of which are more enriched in REE compared with their cortexes, indicating that they underwent the dolomitization of calcareous sediments by hypersaline and subsequent diagenesis decreased the REE content of the cortex because of the low REE concentration of the diagenetic fluids; 2) diagenetic dolomite, which can be subdivided into four groups. (1) burial dolomite which has higher REE concentrations than limestone, but lower than syndepositional dolomite. This shows that pore fluids with high salinity dolomitized the pre-existing limestone; (2) void filling dolomite which has the similar REE patterns with the matrix dolomite. In addition, the Eu anomaly is not obvious, suggesting that the dolomitization fluids originated from the diagenetic fluids; (3) recrystallized dolomite, whose REE concentration was obviously decreased, indicating that the REE concentration was decreased during the recrystallization processes; and (4) hydrothermal altered void-filling dolomite, which has the lowest REE concentration, but obvious positive Eu anomaly, reflecting its hydrothermal activity related origin. Thus, the diverse REE signatures, which were recorded in different dolomites, retain the information of their formation conditions and subsequent diagenetic processes. In situ REE analysis of dolomite is an effective probe into the origin and diagenetic process of

  17. Using in situ REE analysis to study the origin and diagenesis of dolomite of Lower Paleozoic,Tarim Basin


    In situ REE concentrations of various dolomites from Tarim Basin were obtained by LA-ICP-MS analysis,and the data were normalized to standard seawater(Seawater Normalized=SWN).Most of the samples have a ΣREE range of less than 20 ppm.All samples show similar REESWN distributions with heavy REE depletion,and positive Ce anomaly,which indicates that they have the same dolomitization fluids(seawater).According to the origin and diagenetic process of dolomite,two types of dolomite are determined and described as follows:1) syndepositional dolomite,with the highest REE concentrations(more than 20 ppm),the cores of which are more enriched in REE compared with their cortexes,indicating that they underwent the dolomitization of calcareous sediments by hypersaline and subsequent diagenesis decreased the REE content of the cortex because of the low REE concentration of the diagenetic fluids;2) diagenetic dolomite,which can be subdivided into four groups.(1) burial dolomite which has higher REE concentrations than limestone,but lower than syndepositional dolomite.This shows that pore fluids with high salinity dolomitized the pre-existing limestone;(2) void filling dolomite which has the similar REE patterns with the matrix dolomite.In addition,the Eu anomaly is not obvious,suggesting that the dolomitization fluids originated from the diagenetic fluids;(3) recrystallized dolomite,whose REE concentration was obviously decreased,indicating that the REE concentration was decreased during the recrystallization processes;and(4) hydrothermal altered void-filling dolomite,which has the lowest REE concentration,but obvious positive Eu anomaly,reflecting its hydrothermal activity related origin.Thus,the diverse REE signatures,which were recorded in different dolomites,retain the information of their formation conditions and subsequent diagenetic processes.In situ REE analysis of dolomite is an effective probe into the origin and diagenetic process of dolomite.

  18. Siderite (FeCO3)—the Hidden (but Primary) Player in Iron Diagenesis of Non-Marine Sandstones

    Loope, D.; Kettler, R. M.


    Siderite precipitates in reducing pore waters in which iron reduction exceeds sulfate reduction. Abundant siderite should be expected in non-marine strata in which a reductant was present. The Triassic Shinarump Member (Chinle Fm) and Cretaceous Dakota Fm are fluvial and contain siderite in outcrops of floodplain mudstones. Siderite is present in cores of Dakota channel sandstones. Rinded and jointed iron-oxide concretions, Wonderstone patterns, and rhombic, iron-oxide pseudomorphs are present in outcrops of these sandstones. Vascular plants growing on floodplains provided the reductant. Similar concretions, patterns, and pseudomorphs are present in outcropping eolian cross-strata of the Jurassic Navajo Sandstone and in fluvial sandstone of the Cambrian Umm Ishrin Fm. Bleached sandstones indicate reductant was present in both units during late diagenesis. Because Jurassic deserts and Cambrian river systems lacked vascular plants, extra-formational methane was the likely reductant. We interpret the various iron-oxide-cemented phenomena of the Shinarump, Dakota, Navajo, and Umm Ishrin as products of siderite oxidation that accompanied exhumation. In the Navajo, large concretions are enclosed in thick sheaths of iron-oxide cement. Through-going horizontal and vertical joints cut sheaths. Outside concretion sheaths, joints are unassociated with iron-oxide cements, but inside the sheaths, thick cement zones are present on both sides of (still-open) joints. Joints were conduits for oxidizing water entering the concretions. Redox gradients formed on both sides of joints and iron oxide accumulated as Fe+2 diffused from dissolving siderite toward joints and O2 diffused away from joints. Horizontal joints formed <100 m from the land surface. Iron-oxide accumulations on the horizontal joints and on the vertical joints that abut them (see figure) are evidence that siderite oxidation is ongoing and linked to exhumation.

  19. Magnetic mineral diagenesis in the post-glacial muddy sediments from the southeastern South Yellow Sea:Response to marine environmental changes

    LIU Jian; ZHU Rixiang; LI Shaoquan; Jeong-Hae Chang


    Core YSDP103 was retrieved in the muddy deposit under the cold eddy of the southeastern South Yellow Sea, and the uppermost 29.79 m core represents the muddy sediments formed in the shelf since about 13 ka BP. The lower part from 29.79 to 13.35 m, called Unit A2, was deposited during the period from the post-glacial transgression to the middle Holocene (at about 6 14C ka BP) when the rising sea level reached its maximum, while the upper part above 13.35 m (called Unit A1) was deposited in a cold eddy associated with the formation of the Yellow Sea Warm Current just after the peak of post-glacial sea level rise. Rock-magnetic properties of the uppermost 29.79 m core were investigated in detail. The experimental results indicate that the magnetic mineralogy of the core is dominated by magnetite, maghemite and hematite and that, except for the uppermost 2.35 m, the magnetic minerals were subject to reductive diagenesis leading to significant decline of magnetic mineral content and the proportion of low-coercivity component. More importantly, ferrimagnetic iron sulphide (greigite) is found in Unit A2 but absent in Unit A1, suggesting the control of marine environmental conditions on the magnetic mineral diagenesis. Magnetic parameters show abrupt changes across the boundary between Units A1and A2, which reflects a co-effect of environmental conditions and primary magnetic components of the sediments on the diagenesis. Alternating zones of high and low magnetic parameters are observed in Unit A2, which is presumably due to periodic changes of the concentration and/or grain size of magnetic minerals carried into the study area.

  20. Geochemistry of Sedimentation and Diagenesis in Qixia Formation (Early Permian) of Badong,Hubei Province, China: Implications for T-R Cycle Interpretation


    Combined with sedimentary observation and mineralogical research on a type of drusy celestite of early diagenesis in origin, this geochemical study on the Qixia Formation at the Shuibuya Section, Badong County, Hubei Province of south China evaluates the contribution of sedimentation and diagenesis to the mass fractions of CaO, Al2O3, MgO, SiO2, Fe2O3, Na2O, K2O, Mn, Sr, P and Ba in the carbonates. The Sr, initially released from the stabilization of carbonate calcium mineral, precipitated with sulfate ion as celestite in early diagenetic environment, where sulfate reduction was the minimum. Then it redistributed in burial diagenetic environment, where celestite was replaced by calcite. The fractions of the MgO and SiO2 in the carbonates were mainly modified by the early dolomitization and silicification respectively. That of the Na2O was overprinted by the burial diagenesis. Multivariate statistical analysis on data of sixty bulk rocks indicates that the mass fractions of the Al2O3, K2O, Fe2O3, Mn, CaO, P and Ba were affiliated with the sedimentary factor despite the obvious decrease of CaO during early dolomitization and silicification. Among them, the Al2O3 and K2O mainly represent the detrital components. In addition, a dysaerobic sedimentary background was confirmed by trace element measurement and information derived from the formation of the celestite. This genetic discrimination facilitates the interpretation of the transgressive-regressive (T-R) cycle and specialities featured this unusual carbonate unit.

  1. Refining the Neoproterozoic and Early Paleozoic record of carbon cycling and seawater chemistry using quantitative geochemical models of redox dynamics and carbonate diagenesis

    Ahm, Anne-Sofie Crüger

    This thesis explores the ancient sedimentary archive of Earth history and examines enigmatic climatic transitions that may have shaped the evolution of animal life. Much of our understanding of the climatic history of Earth is based on chemical and isotopic measurements of ancient sediments. One...... of the main limitations of this archive, however, is the susceptibility of sediments to diagenesis that can alter the primary chemical signals. For example, the concentration of iron (Fe) in specific mineral phases is used to infer oxygen concentrations in the ancient water column. Chapter 2 of this thesis...

  2. The relationship between dolomitization and organic matter occurrence in Lower Paleozoic carbonate in the Ordos Basin


    Based on observations on the core and surface sections of Lower Paleozoic carbonate in the Ordos Basin, petrography research and measurements of TOC, TOS , Ro, XRD, and comparative study with dolomite in modern Coorong Lake, it has been revealed that: (i)dolomitization may occur in micrite limestone, gypsum-halite and argillaceous sandstone, and it can be divided into three types: sedimentary penecontemporaneous-early diagenesis, late diagenesis of deep burial and catagenesis of uplift period. However, the crystal cell of the second type less than 35 μ m in size is most closely associated with gas pool; (ii) the highest content of organic matter (OM) is produced in samples from the argillic dolomite which may be formed by argillaceous fluid through gypsum-halite; (iii) in the evolution process from penecontemporaneous dolomite into stoichiometric dolomite, the crystal order of dolomite and the porosity of its host rock tend to increase, which is favorable to the formation of an available migration network. When the power of the fluid is high enough, the network is mainly favorable to the migration and transport of heat, but when the power of the fluid goes down, the network system is favorable, due to its large space, to OM deposition in it.

  3. Halal Matters

    In today’s globalized world, halal (meaning ‘permissible’ or ‘lawful’) is about more than food. Politics, power and ethics all play a role in the halal industry in setting new standards for production, trade, consumption and regulation. The question of how modern halal markets are constituted...... is illustrated by rich ethnographic case studies from a range of contexts, and consideration is given to both Muslim majority and minority societies. Halal Matters will be of interest to students and scholars working across the humanities and social sciences, including anthropology, sociology and religious...

  4. Active matter

    Ramaswamy, Sriram


    The study of systems with sustained energy uptake and dissipation at the scale of the constituent particles is an area of central interest in nonequilibrium statistical physics. Identifying such systems as a distinct category—Active matter—unifies our understanding of autonomous collective movement in the living world and in some surprising inanimate imitations. In this article I present the active matter framework, briefly recall some early work, review our recent results on single-particle and collective behaviour, including experiments on active granular monolayers, and discuss new directions for the future.

  5. Detailed sedimentology and geomorphology elucidate mechanisms of formation of modern and historical sequences of minor moraines in the European Alps

    Wyshnytzky, Cianna; Lukas, Sven


    Suites of closely-spaced minor moraines may help further understanding of glacier retreat and predict its geomorphological effects through the observations of moraine formation on short timescales. This research is common in lowland, maritime settings (Sharp, 1984; Boulton, 1986; Krüger, 1995; Reinardy et al., 2013), but remains sparse in high-mountain settings (Hewitt, 1967; Ono, 1985; Beedle et al., 2009; Lukas, 2012). This research presents detailed sedimentological and geomorphological research on minor moraines at two high-mountain settings in the Alps: Silvrettagletscher, Switzerland, as a modern setting and Schwarzensteinkees, Austria, as a historical setting. Geomorphological investigations included mapping and measurements through field observations and assessing aerial imagery. Additionally, terrestrial laser scanning and ground-penetrating radar data were collected in the Schwarzensteinkees foreland. Detailed sedimentological investigations followed excavation of seven moraines at Silvrettagletscher and five moraines at Schwarzensteinkees and include multiple scales of observation and measurements to support interpretations of sediment transport and deposition (e.g. Evans and Benn, 2004). The modern moraines at Silvrettagletscher, in the immediately proglacial foreland, have been forming since before 2003. Four mechanisms of formation show distinct sedimentological signatures: formerly ice-cored moraines (e.g. Kjær & Krüger, 2001; Lukas, 2012; Reinardy et al., 2013) , push moraine formation on a reverse bedrock slope (e.g. Lukas, 2012), push moraine formation incorporating sediments deposited in a former proglacial basin, and basal freeze-on (e.g. Andersen & Sollid, 1971; Krüger, 1995; Reinardy et al., 2013). Schwarzensteinkees still exists but is currently restricted to steeply-dipping bedrock slabs above the main valley. This study therefore investigates the moraines in the foreland that formed between approximately 1850 and 1930. The minor

  6. Mimicking Dark Matter

    Bel, Lluís


    I show that a very simple model in the context of Newtonian physics promoted to a first approximation of general relativity can mimic Dark matter and explain most of its intriguing properties. Namely: i) Dark matter is a halo associated to ordinary matter; ii) Dark matter does not interact with ordinary matter nor with itself; iii) Its influence grows with the size of the aggregate of ordinary matter that is considered, and iv) Dark matter influences the propagation of light.

  7. Shoreline deposits and diagenesis resulting from two Late Pleistocene highstands near +5 and +6 metres, Durban, South Africa

    Cooper, J.A.G.; Flores, R.M.


    In exposures of Pleistocene rocks on the east coast of South Africa, eight sedimentary facies were distinguished on the basis of petrology, grain size, internal structures and field relationships. These are interpreted as deposits of surf zone, breaker zone, swash zone, backbeach, boulder beach and dune environments. Three phases of deposition and diagenesis are recognized. As a result of the stabilising effect of pre-existing coastal facies, the deposits from successive sea level stands are stacked vertically in a narrow coast-normal strip. Early cementation prevented erosion of the deposits during subsequent transgressions. Deposition of subsequent facies took place on an existing coastal dune (Facies 1). A terrace was cut into this dune at a sea level 4.5 to 5 m above present. At this sea level, clastic shoreline sediments were deposited which make up the main sedimentary sequence exposed (Facies 2-7). The steep swash zone, coarse grain size, and comparison with modern conditions in the study area indicate clastic deposition on a high-energy, wave-dominated, microtidal coastline. Vertical stacking of progressively shallower water facies indicates progradation associated with slightly regressive conditions, prior to stranding of the succession above sea level. During a subsequent transgression to 5.5 or 6 m above present sea level, a second terrace was cut across the existing facies, which by then were partly lithified. A boulder beach (Facies 8) deposited on this terrace is indicative of high wave energy and a rocky coastline, formed by existing cemented coastal facies. Comparison with dated deposits from other parts of the South African coast suggest a Late Pleistocene age for Facies 2-8. Deposition was terminated by subsequent regression and continuing low sea levels during the remainder of the Pleistocene. Cementation of the facies took place almost entirely by carbonate precipitation. The presence of isopachous fibrous cements suggests early cementation of

  8. Quantitative Chemical Mass Transfer in Coastal Sediments During Early Diagenesis: Effects of Biological Transport, Mineralogy, and Fabric Phase 3


    Stennis Space Center (NRL), and Georgia Technological University (GTU). This consortium is working together to integrate controlled laboratory...Jannasch, Monterrey Bay Aquarium Research Institute) and the technique published. A general model for microfabric-induced preservation of organic matter

  9. Maxwell Matters

    Eisenberg, Bob


    Charges are everywhere because most atoms are charged. Chemical bonds are formed by electrons with their charge. Charges move and interact according to Maxwell's equations in space and in atoms where the equations of electrodynamics are embedded in Schroedinger's equation as the potential. Maxwell's equations are universal, valid inside atoms and between stars from times much shorter than those of atomic motion (0.1 femtoseconds) to years (32 mega-seconds). Maxwell's equations enforce the conservation of current. Analysis shows that the electric field can take on whatever value is needed to ensure conservation of current. The properties of matter rearrange themselves to satisfy Maxwell's equations and conservation of current. Conservation of current is as universal as Maxwell's equations themselves. Yet equations of electrodynamics find little place in the literature of material physics, chemistry, or biochemistry. Kinetic models of chemistry and Markov treatments of atomic motion are ordinary differential eq...

  10. Sedimentology of seismo-turbidites off the Cascadia and northern California active tectonic continental margins, Pacific Ocean

    Gutierrez Pastor, Julia; Nelson, Hans; Goldfinger, Chris; Escutia, Carlota


    Holocene turbidites from turbidite channel systems along the active tectonic continental margins of the Cascadia subduction zone (offshore Vancouver Island to Mendocino Triple Junction) and the northern San Andreas Transform Fault (the Triple Junction to San Francisco Bay), have been analyzed for sedimentologic features related to their seismic origin. Centimeter thick silt/sand beds (turbidite base) capped by mud layers (turbidite tail) and interbedded with hemipelagic silty clay intervals with high biogenic content have been characterized by visual core descriptions, grain-size analysis, X-ray radiographs and physical properties. Along the northern California margin in upstream single tributary canyons and channels, most turbidites are uni-pulsed (classic fining up) whereas downstream below multiple tributary canyon and channel confluences, most deposits are stacked turbidites. Because each set of stacked turbidites has no hemipelagic sediment between each turbidite unit and each unit has a distinct mineralogy from a different tributary canyon, we interpret that a stacked turbidite is deposited by several coeval turbidity currents fed by multiple tributary canyons and channels with synchronous triggering from a single San Andreas Fault earthquake. The Cascadia margin is characterized by individual multi-pulsed turbidites that contain multiple coarse-grained sub-units without hemipelagic sediment between pulses. Because the number and character of multiple coarse-grained pulses for each correlative multi-pulsed turbidite is almost always constant both upstream and downstream in different channel systems for 600 km along the margin,we interpret that the earthquake shaking or aftershock signature is usually preserved, for the much stronger Cascadia (≥9 Mw) compared to weaker California (≥8Mw) earthquakes, which result in upstream uni-pulsed turbidites and downstream stacked turbidites. Consequently, both the strongest (≥9 Mw) great earthquakes and downstream

  11. The September 16, 2015 Illapel Tsunami - Sedimentology of tsunami deposits at the beaches of La Serena and Coquimbo

    Bahlburg, H.; Nentwig, V.; Kreutzer, M.


    On September 16, 2015, a Mw 8.3 earthquake occurred off the coast of Central Chile, 46 km west of the town of Illapel, the hypocenter was at a depth of 8.7 km in the transition zone from the Chilean flat slab to the central Chilean steep slab subduction geometry, and near the intersection of the Juan Fernandez Ridge with the South America plate. The quake caused a tsunami registered which at Coquimbo and La Serena (c. 30°S) attained wave heights of 4.5 m leading to flooding and destruction of infrastructure. Maximum inundation distance was c. 700 m in Coquimbo Bay with minor flooding at the beaches of La Serena to the N. Tsunami deposits are usually the only observable evidence of past events. In view of a limited preservation potential, it is of paramount importance to undertake detailed studies in the wake of actual events. We report initial field data of a sedimentological post-tsunami field survey undertaken in October 2015. The most comprehensive sedimentological record of this tsunami is preserved at Playa Los Fuertes in La Serena. Along a 30 m long trench perpendicular to the coast we observed a laminated package of tsunami deposits. Above an erosive basal unconformity with an amplitude of up to 50 cm the deposit consists of 6 layers of variable thickness, ranging between dark laminae a few millimeters thick and rich in heavy minerals, and lighter colored sand layers up to 15 cm thick. The sediments are moderately well to well sorted, unimodal with modes between 1.3 and 2.0 Φ (medium sand). Cross-beds in the lower four layers indicate deposition from tsunami inflow, cross bedding in the penultimate layer records outflow. Water escape through small sand volcanoes was coeval to formation of the overlying sediment layer by traction deposition. This simultaneity is indicated by sand issued from the lower layer which has been preserved as a thin plume deformed in the downcurrent, i.e. landward, direction in the newly forming upper layer. Other sectors of the

  12. 550 years in sedimentological record from a varved type lake (Bolătău, Bukovina, NE Romania - changing storm frequency and climate fluctuation

    Alexandra NEMETH


    Full Text Available In the present paper we introduce lake Bolătău, located in Obcina Feredeului, Eastern Carpathians (Romania, with seasonally controlled sedimentation and significant potential for generating precipitation sensitive proxy record. Two sediment cores were compared against each other in order to achieve a better understanding of the lateral discontinuity of observed microfacies and an accurate interpretation of the sedimentological data.

  13. Geochemical modeling of water-gas-rock interactions. Application to mineral diagenesis in geologic reservoirs; Modelisation geochimique des interactions eau-gaz-roche. Application a la diagenese minerale dans les reservoirs geologiques

    Bildstein, O.


    The Ph.D. report describes a conceptual and numerical model for simulating gas-water-rock interaction during mineral diagenesis of sediments. The main specific features of this model are the following: applicable to open systems, half-implicit resolution numerical method, feedback on the texture evolution (grain model), existence of a gas phase, oxido-reduction phenomena. (author) 217 refs.

  14. Baryonic matter and beyond

    Fukushima, Kenji


    We summarize recent developments in identifying the ground state of dense baryonic matter and beyond. The topics include deconfinement from baryonic matter to quark matter, a diquark mixture, topological effect coupled with chirality and density, and inhomogeneous chiral condensates.

  15. Culture Matters

    Gillian Warner-Søderholm


    Full Text Available Whether managers are concerned with financial issues, marketing, or human resource management (HRM, cultural values and practices do matter. The purpose of this article is to understand Norwegian managers’ cultural values within the cross-cultural landscape of her neighbors in the “Scandinavian cluster.” Clearly, subtle but disturbing differences may surface even when representatives from similar cultures work together. As a follow on from the GLOBE project, data based on the GLOBE instrument were collected on culture and communication values in Norway from 710 Norwegian middle managers for this present study. Although the Scandinavian cultures appear ostensibly similar, the results illustrate that research can reveal subtle but important cultural differences in nations that are similar yet dissimilar. All three Scandinavian societies appear intrinsically egalitarian; they appear to value low Power Distance, directness, and consensus in decision making and to promote Gender Egalitarianism. Nevertheless, there are significant differences in the degrees of commitment to these values by each individual Scandinavian partner. These differences need to be understood and appreciated to avoid misunderstandings.

  16. Geomorphologic, stratigraphic and sedimentologic evidences of tectonic activity in Sone–Ganga alluvial tract in Middle Ganga Plain, India

    Sudarsan Sahu; Dipankar Saha


    The basement of the Ganga basin in the Himalayan foreland is criss-crossed by several faults, dividing the basin into several sub-blocks forming horsts, grabens, or half-grabens. Tectonic perturbations along basement faults have affected the fluvial regime and extent of sediment fill in different parts of the basin during Late Quaternary. The East Patna Fault (EPF) and the West Patna Fault (WPF), located in Sone–Ganga alluvial tract in the southern marginal parts of Middle Ganga Plain (MGP), have remained tectonically active. The EPF particularly has acted significantly and influenced in evolving the geomorphological landscape and the stratigraphic architecture of the area. The block bounded by the two faults has earlier been considered as a single entity, constituting a half-graben. The present investigation (by morpho-stratigraphic and sedimentologic means) has revealed the existence of yet another fault within the half-graben, referred to as Bishunpur–Khagaul Fault (BKF). Many of the long profile morphological characters (e.g., knick-zone, low width–depth ratio) of the Sone River at its lower reaches can be ascribed to local structural deformation along BKF. These basement faults in MGP lie parallel to each other in NE–SW direction.

  17. A 2D hydrodynamic-sedimentological model for gravel-bed rivers. Part I: theory and validation

    Gabriel Kaless


    Full Text Available This paper presents a novel 2D-depth average model especially developed for gravel-bed rivers, named Lican-Leufú (Lican=pebble and Leufu=river, in Mapuche’s language, the native inhabitants of Central Patagonia, Argentina. The model consists of three components: a hydrodynamic, a sedimentological, and a morphological model. The flow of water is described by the depth-averaged Reynolds equations for unsteady, free-surface, shallow water flows. It includes the standard k-e model for turbulence closure. Sediment transport can be divided in different size classes (sand-gravel mixture and the equilibrium approach is used for Exner’s equation. The amour layer is also included in the structure of the model and the surface grain size distribution is also allowed to evolve. The model simulates bank slides that enable channel widening. Models predictions were tested against a flume experiment where a static armour layer was developed under conditions of sediment starvations and general good agreements were found: the model predicted adequately the sediment transport, grain size of transported material, final armour grain size distribution and bed elevation.

  18. Late Quaternary stratigraphy, sedimentology, and geochemistry of an underfilled lake basin in the Puna (north-west Argentina)

    McGlue, Michael M.; Cohen, Andrew S.; Ellis, Geoffrey S.; Kowler, Andrew L.


    Depositional models of ancient lakes in thin-skinned retroarc foreland basins rarely benefit from appropriate Quaternary analogues. To address this, we present new stratigraphic, sedimentological and geochemical analyses of four radiocarbon-dated sediment cores from the Pozuelos Basin (PB; northwest Argentina) that capture the evolution of this low-accommodation Puna basin over the past ca. 43 cal kyr. Strata from the PB are interpreted as accumulations of a highly variable, underfilled lake system represented by lake-plain/littoral, profundal, palustrine, saline lake and playa facies associations. The vertical stacking of facies is asymmetric, with transgressive and thin organic-rich highstand deposits underlying thicker, organic-poor regressive deposits. The major controls on depositional architecture and basin palaeogeography are tectonics and climate. Accommodation space was derived from piggyback basin-forming flexural subsidence and Miocene-Quaternary normal faulting associated with incorporation of the basin into the Andean hinterland. Sediment and water supply was modulated by variability in the South American summer monsoon, and perennial lake deposits correlate in time with several well-known late Pleistocene wet periods on the Altiplano/Puna plateau. Our results shed new light on lake expansion–contraction dynamics in the PB in particular and provide a deeper understanding of Puna basin lakes in general.

  19. Seismic sedimentology of conglomeratic sandbodies in lower third member of Shahejie Formation (Palaeogene) in Shengtuo area, East China

    袁勇; 张金亮; 李存磊; 孟宁宁; 李岩


    The sand-conglomerate fans are the major depositional systems in the lower third member of Shahejie Formation in Shengtuo area, which formed in the deep lacustrine environment characterized by steep slope gradient, near sources and intensive tectonic activity. This work was focused on the sedimentary feature of the glutenite segment to conduct the seismic sedimentology research. The near-shore subaqueous fans and its relative gravity channel and slump turbidite fan depositions were identified according to observation and description of cores combining with the numerous data of seismic and logging. Then, the depositional model was built depending on the analysis of palaeogeomorphology. The seismic attributes which are related to the hydrocarbon but relative independent were chosen to conduct the analysis, the reservoir area of the glutenite segment was found performing a distribution where the amplitude value is relatively higher, and finally the RMS amplitude attribute was chosen to conduct the attribute predicting. At the same time, the horizontal distribution of the sedimentary facies was analyzed qualitatively. At last, the sparse spike inversion method was used to conduct the acoustic impedance inversion, and the inversion result can distinguish glutenite reservoir which is greater than 5 m. This method quantitatively characterizes the distribution area of the favorable reservoir sand.

  20. Stratigraphy, sedimentology, paleontology, and paleomagnetism of Pliocene-early Pleistocene lacustrine deposits in two cores from western Utah

    Thompson, R.S.; Oviatt, Charles G.; Roberts, A.P.; Buchner, J.; Kelsey, R.; Bracht, C.J.; Forester, R.M.; Bradbury, J.P.


    The paleoclimatic history of western Utah is being investigated as part of the USGS Global Change and Climate History Program studies of long-term climatic changes in the western United States. The initial objective of the study is to document the environmental conditions during the mid-Pliocene period of warmer-than-modern global climates (the focus of the USGS Pliocene Research, Interpretation, and Synoptic Mapping [PRISM] project). The investigation also seeks to determine how and when these conditions gave way to the late Quaternary pattern of climatic variations (in which short periods of very moist climates have been separated by long periods of arid conditions). This is a collaborative project involving specialists from the USGS, Kansas State University, and the University of California-Davis in paleontology (Thompson, Buchner, Forester, Bradbury), stratigraphy and sedimentology (Oviatt, Kelsey, Bracht), and paleomagnetism and environmental magnetism (Roberts). The data presented herein represent preliminary findings of the analyses of two cores of Pliocene and early Pleistocene sediments from the eastern Great Basin.

  1. Implications of sedimentological and hydrological processes on the distribution of radionuclides: The example of a salt marsh near Ravenglass, Cumbria

    Carr, A. P.; Blackley, M. W. L.


    This paper summarizes sedimentological and hydrological studies at a salt marsh site on the north bank of the River Esk near Ravenglass which have a bearing on the fate of the low-level radioactive effluent from the reprocessing facility at Sellafield, Cumbria. A range of techniques has been used including electromagnetic distance measurement (EDM) and pore water pressure studies. The results show that: (a) Over a two-year period there were no significant net changes in salt marsh creek level, although shorter-term (probably seasonal) fluctuations, of the order of 2 cm, occurred. These were attributed to expansion of clay particles during the winter months. Nearby, however, there were vertical changes of the order of 1 m due to erosion. (b) Pore water pressures indicated a dynamic situation with very rapid responses both to tidal fluctuations and to rainfall. During neap tides there was clear evidence for water seeping upwards from the underlying clay/sand interface. Shortlived radionuclides ( 95Zr/95Nb and 106Ru) were detected in this zone. (c) Soil polygons, once initiated by desiccation, thereafter provide preferential routes for water (and radionuclides) to the sub-surface sediment. These, and other results, are discussed in the context of previous studies. It is concluded that the complexity of the estuarine environment results in most data being site specific.

  2. Implications of sedimentological and hydrological processes on the distribution of radionuclides: the example of a salt marsh near Ravenglass, Cumbria

    Carr, A.P.; Blackley, M.W.L.


    This paper summarizes sedimentological and hydrological studies at a salt marsh site on the north bank of the River Esk near Ravenglass which have a bearing on the fate of the low-level radioactive effluent from the reprocessing facility at Sellafield, Cumbria. A range of techniques has been used including electromagnetic distance measurement (EDM) and pore water pressure studies. The results show that: (a) Over a two-year period there were no significant net changes in salt marsh creek level, although shorter-term (probably seasonal) fluctuations, of the order of 2 cm, occurred. These were attributed to expansion of clay particles during the winter months. Nearby, however, there were vertical changes of the order of 1 m due to erosion. (b) Pore water pressures indicated a dynamic situation with very rapid responses both to tidal fluctuations and to rainfall. During neap tides there was clear evidence for water seeping upwards from the underlying clay/sand interface. Shortlived radionuclides (/sup 95/Zr//sup 95/Nb and /sup 106/Ru) were detected in this zone. (c) soil polygons, once initiated by desiccation, thereafter provide preferential routes for water (and radionuclides) to the sub-surface sediment. These, and other results, are discussed in the context of previous studies. It is concluded that the complexity of the estuarine environment results in most data being site specific.

  3. Reconnaissance sedimentology of selected tertiary exposures in the upland region bordering the Yukon Flats basin, east-central Alaska

    LePain, David L.; Stanley, Richard G.


    This report summarizes reconnaissance sedimentologic and stratigraphic observations made during six days of helicopter-supported fieldwork in 2002 on Tertiary sedimentary rocks exposed in the upland region around the flanks of the Yukon Flats basin in east-central Alaska (fig. 1). This project was a cooperative effort between the Alaska Division of Geological & Geophysical Surveys (DGGS) and the U.S. Geological Survey (USGS) to investigate the geology of the basin in preparation for an assessment of the undiscovered, technically recoverable hydrocarbon resources (Stanley and others, 2004). Field observations and interpretations summarized in this report are reconnaissance level. At most, no more than a few hours were spent on the ground at any location. Measured sections included in this report are sketch sec- tions and thicknesses shown are approximate. Relatively detailed observations were made by the authors at only three locations, including The Mudbank (Hodzana River), Rampart (east bank of the Yukon River), and Bryant Creek (along the Tintina fault near the Canada border). These three locations are described first in relative detail, then followed by general descriptions of other locations.

  4. A 2D hydrodynamic-sedimentological model for gravel bed rivers. Part II, Case study: the Brenta River in Italy

    Gabriel Kaless


    Full Text Available A 2D depth average model has been used to simulate water and sediment flow in the Brenta River so as to interpret channel changes and to assess model predictive capabilities. The Brenta River is a gravel bed river located in Northern Italy. The study reach is 1400 long and has a mean slope of 0.0056. High resolution digital terrain models has been produced combining laser imaging detection and ranging data with colour bathymetry techniques. Extensive field sedimentological surveys have been also carried out for surface and subsurface material. The data were loaded in the model and the passage of a high intense flood (R.I. > 9 years was simulated. The model was run under the hypothesis of a substantial equilibrium between sediment input and transport capacity. In this way, the model results were considered as a reference condition, and the potential trend of the reach was assessed. Low-frequency floods (R.I. » 1.5 years are expected to produce negligible changes in the channel while high floods may focalize erosion on banks instead than on channel bed. Furthermore, the model predicts well the location of erosion and siltation areas and the results promote its application to other reaches of the Brenta River in order to assess their stability and medium-term evolution.

  5. Sedimentology and Chronology of Paleogene Coarse Clastic Rocks in East-Central Tibet and Their Relationship to Early Tectonic Uplift

    ZHOU Jiangyu; WANG Jianghai; K. H. BRIAN; A. YIN; M. S. MATTHEW


    A systematic sedimentological and chronological study of typical Paleogene basins in eastcentral Tibet suggests that the depositional characteristics of extensively developed huge-bedded,purplish-red coarse clastic rocks formed in a tectonic setting of regional thrusting and strike-slipping represent a typical dry and hot subaerial alluvial fan environment formed in a proximal and rapidaccumulating sediment body in debris flows and a fan-surface braided river. Combining results from basin-fill sequences, sequences of coarse clastic rocks, fauna and sporo-pollen associations and thermochronological data, it is concluded that the coarse clastic rocks formed in the period of 54.2-belt), middle (Batang-Lijiang fault belt), and disintegration of large basins in the southern (LanpingSimao fold belt) segments of Tibet. The widespread massive-bedded coarse clastic rocks, fold thrusting and strike-slip, thrust shortening, and igneous activities in the Paleogene basins of eastcentral Tibet indicate that an early diachronous tectonic uplift might have occurred in the Tibetan Plateau from Middle Eocene to Oligocene, related to the initial stage of collision of the Indian and Asian plates.

  6. Texture and composition of the Rosa Marina beach sands (Adriatic coast, southern Italy: a sedimentological/ecological approach

    Moretti Massimo


    Full Text Available Beach sands from the Rosa Marina locality (Adriatic coast, southern Italy were analysed mainly microscopically in order to trace the source areas of their lithoclastic and bioclastic components. The main cropping out sedimentary units were also studied with the objective to identify the potential source areas of lithoclasts. This allowed to establish how the various rock units contribute to the formation of beach sands. The analysis of the bioclastic components allows to estimate the actual role of organisms regarding the supply of this material to the beach. Identification of taxa that are present in the beach sands as shell fragments or other remains was carried out at the genus or family level. Ecological investigation of the same beach and the recognition of sub-environments (mainly distinguished on the basis of the nature of the substrate and of the water depth was the key topic that allowed to establish the actual source areas of bioclasts in the Rosa Marina beach sands. The sedimentological analysis (including a physical study of the beach and the calculation of some statistical parameters concerning the grain-size curves shows that the Rosa Marina beach is nowadays subject to erosion.

  7. Historical changes in organic matter input to the muddy sediments along the Zhejiang-Fujian Coast, China over the past 160 years

    Chen, Li-lei; Liu, Jian; Xing, Lei; Krauss, Ken W.; Wang, Jia-sheng; Xu, Gang; Li, Li


    The burial of sedimentary organic matter (SOM) in the large river-influenced estuarine-coastal regions is affected by hydrodynamic sorting, diagenesis and human activities. Typically, the inner shelf region of the East China Sea is a major carbon sink of the Yangtze River-derived fine-grained sediments. Most of the previous work concentrated on the studies of surface sediments or used a single-proxy in this region. In this study, two cores from the Zhejiang-Fujian Coast were analyzed using bulk (TOC, TN and δ13CTOC) and molecular biomarker (n-alkane, brassicasterol, dinosterol and glycerol dialkyl glycerol tetraether lipids) techniques to clarify the sources, spatiotemporal distribution and fate of SOM in the Yangtze River Estuary and adjacent shelf. Results from this study indicated that the effects of diagenesis and diffusion on different sedimentary biomarkers resulted in overestimation of the relative contribution of terrestrial organic matter (%OMterr), compared with those based on δ13CTOC. The amounts of terrestrial plant organic matter (OMplant) and%OMterr in sediments decreased offshore. In contrast, the amounts of marine organic matter (OMmarine) increased offshore, but closer to the Yangtze River mouth, the amounts of soil organic matter (OMsoil) increased. Moreover, the amounts of TOC, OMplant and OMmarine biomarkers increased, but OMsoil and%OMterrdecreased over time in recent decades. Our study suggests that spatial organic matter distribution patterns in marine shelf sediments were controlled primarily by hydrodynamic sorting and nutrient concentrations, and temporally diverse patterns were controlled predominantly by anthropogenic influence (e.g., dam construction and soil conservation, reclamation and agricultural plantations, anthropogenic nutrient input, dust storms, eutrophication, etc) and climate events (e.g., interdecadal climatic jump and heavy rain events) in the geological period.

  8. Reservoir diagenesis of 3rd member of Feixianguan Formation, Jiannan Gas Field%建南气田飞三段储层成岩作用研究

    鲍云杰; 王恕一; 蒋小琼; 管宏林; 杨振恒


    以建43井为例,研究了建南气田三叠系飞三段储层的成岩作用及特点,其中白云岩化作用、溶蚀作用和构造破裂作用对储层贡献较大.其成岩序列为藻粘结、泥晶化→一世代胶结→大气淡水溶蚀→二世代粒状胶结→新生变形→压实压溶→白云岩化→早期张裂缝及充填→构造挤压作用→埋藏溶蚀Ⅰ→进油→白云石、萤石充填、石英充填交代→油演化为沥青→埋藏溶蚀Ⅱ→晚期张裂缝→进气;主要经历了海底(潮间)环境、大气淡水环境、浅埋藏和深埋藏环境.白云石晶体、二世代粒状胶结物、萤石被溶蚀、压性裂缝发育以及孔隙无明显变形是埋藏溶蚀的主要识别标志.%Diagenesis and features of the 3rd member of Feixianguan Formation in the Jiannan Gas Field were studied taking well Jian43 as an example. Dolomitization, karstification and tectonic disruption were contributive to reservoir. Diagenesis sequence was illustrated as follows: algae agglutinate and micritization-"first consolidation-*" atmospheric water erosion-*-secondary granular consolidation-" neo-morphism-" compaction and pressolution-" dolomitization-?■ early tension fissure and filling-"tectonic compression-" buried erosion I -"petroleum entering-"dolomite and fluorite filling as well as quartz filling and metasomatisnr~"oil evolving to bitumen-"buried erosion E~"late tension fissure-"gas entering. There were 4 kinds of diagenesis environment including seabed (intertidal), atmospheric water, shallow bury and deep bury. Dolomite crystals, secondary granular consolidations, eroded fluorites, tensional fissures and pores without obvious deformation were the main identifications for buried erosions.

  9. Hydrological and sedimentological regime of lower Vistula fluvial lakes (North Central Poland)

    Kordowski, Jarosław; Kubiak-Wójcicka, Katarzyna; Tyszkowski, Sebastian; Solarczyk, Adam


    Regarding the outflow the Vistula River is the largest river in the Baltic catchment. In its lower course it has developed an anastomosing channel pattern modified strongly by intensive human hydrotechnical activity and by the regulation which have intensified about 200 years ago. Channel regulation apart from already existing lakes have left many new artificially created ones. This activity have also altered the hydrological and sedimentary regime. It turned out that only the small portion of the lakes infilled rapidly but the majority have persisted to present day almost unchanged in spite of regulation. The reason of this resistence to silting is connected with specific interaction of sediment removing during high flood water episodes and strong groundwater circulation in former river arms transformed in present-day lakes. As an example of a lake with an intensive groundwater exchange rate with the main Vistula channel and supposed Quaternary and Tertiary aquifers was selected the Old Vistula lake (Stara Wisła) near Grudziądz town. It has got an area of 50 ha, mean depth 1,73 m, maximum depth 8 m, length about 4 km and medium width about 100 m. In the years 2011-2015 in its surficial water were conducted measures with two weeks frequency which included: temperature, pH, Eh, suspended matter amount, total and carbonaceous mineralization. For comparison similar measurements were also conducted in other fluvial lakes and Vistula tributaries. Hydrological data were supplemented by geological investigations of floodplain sediments cover which has important impact on the rate of groundwater migration and circulation. Investigations carried proved that there exists distinct gradient of carbonaceous mineralization from small values in the Vistula channel to high values at the valley edges. PH and Eh parameters in the Old Vistula lake were different than in all other surveyed sites what leads to conclusion that it is fed by deeper groundwaters than in the case of other

  10. Variations in sedimentological properties in Lake Challa, East Africa: Understanding the source to sink processes

    Meyer, Inka; Eloy, Jonas; Verschuren, Dirk; De Batist, Marc


    The clastic mineral fraction of lacustrine sediments has been proven to provide valuable information about sedimentation dynamics within a lake, and it can be used to define distinct terrestrial source areas and transport mechanisms from source to sink. Down-core variation in the properties of the clastic mineral fraction yields indications for changes in terrestrial sediment sources over time. However, in order to use terrestrial proxies in palaeo-environmental reconstruction, we have to understand and quantify the modern conditions of sediment provenance and deposition at the study site. In this study we present data on grain-size distribution, mineralogy and particle shape of the clastic mineral component of lacustrine sediments from Lake Challa, a small freshwater lake of volcanic origin, located on the eastern slope of Mt. Kilimanjaro. Situated close to the equator, it contains a uniquely long and continuous sediment sequence allowing the study of inter-hemispheric climate dynamics. The finely laminated profundal sediments of Lake Challa are characterized by a fine-grained texture and are mainly composed of organic matter, biogenic silica and authigenic carbonate, with a relatively minor component of detrital mineral that can either originate from erosion of the steep volcanic crater walls or was mobilized by wind from unvegetated areas of the surrounding scrub savannah landscape. In order to distinguish between these two sources of terrestrial sediment input (i.e., local run-off versus distant aeolian) into Lake Challa, and to map out differences in sediment properties, samples were investigated from profundal surface sediments and short cores, as well as on-shore soils from several locations around the lake and from beyond the crater catchment. Variation in grain-size distribution and mineralogy can be linked to distinct terrestrial sources, whereas the shape of single particles gives additional information about transport dynamics. In future, the results

  11. The influence of climate on early and burial diagenesis of Triassic and Jurassic sandstones from the Norwegian – Danish Basin

    Weibel, Rikke; Olivarius, Mette; Kjøller, Claus


    the humid climate, kaolinite precipitated due to leaching of feldspar and mica, and the abundant organic matter caused reducing conditions, which led to other Fe-rich phases, i.e. pyrite, Fe-chlorite and siderite. The inherited early diagenetic pore fluids and mineral assemblage also affect the mineral...

  12. Microfacies, sedimentary environment and diagenesis of the upper part of Dalan and Kangan Formations in the Kuh-e Surmeh area, Folded Zagros

    Mohammadhossein Adabi


    Full Text Available The upper part of Dallan and Kangan formations (Permian-Triassic, are located in the Kuh-e Surmeh area in folded Zagros Basin with a thickness of 325 m overlying by Nar evaporite member and underlying by Dashtak Formation. Dominant lithology of these formations are limestone and dolomite. Our purpose in this study is to identify microfacieses, sedimentary environment and diagenetic proceses. To overcome this aim, thin sections petrographic studies, leaded to identify 12 microfacieses related to 4 facieses belt: tidal flat, lagoon, shoal and open marine. The observed microfacies patterns indicate a ramp carbonate platform as depositional environment. Based on petrographic studies, the important diagenetic processes in these formations consist of: micritization, dolomitization, cementation, stilolitization and chemical and physical compactions. Burial diagenesis is dominated diagenetic event. The observed porosities in this section are primary and secondary such as fenestral, vuggy, fracture, moldic, interparticle, intraparticle and channel

  13. Refining the Neoproterozoic and Early Paleozoic record of carbon cycling and seawater chemistry using quantitative geochemical models of redox dynamics and carbonate diagenesis

    Ahm, Anne-Sofie Crüger

    This thesis explores the ancient sedimentary archive of Earth history and examines enigmatic climatic transitions that may have shaped the evolution of animal life. Much of our understanding of the climatic history of Earth is based on chemical and isotopic measurements of ancient sediments. One...... demonstrates that modern weathering processes remobilize reactive Fe in outcrop samples which leads to a loss of specific minerals phases (pyrite) and a gain of others (Fe-oxides). These results highlight the need for caution when using Fe-speciation to catalog past environment redox change from purely outcrop...... through diagenesis and provide more robust estimates for past seawater chemistry. Ancient carbonate rocks with extreme negative carbon isotopes are found worldwide bracketing the Marinoan glaciation (∼635 Ma). There is no scientific consensus as to whether these excursions originate from a primary...

  14. 232Th-228Ra-228Th Recording of Estuarine and Coastal Sedimentological Events

    Hillaire-Marcel, C.; Ghaleb, B.; Ruiz-Fernandez, A.


    Climatic events (e.g., storminess, floods) and river/coastal management activities (e.g., dredging) may result in the removal and re-suspension of contaminated sediments in shallow coastal areas and estuaries, thus leading to long-term contamination of such environments. Short-lived daughter isotopes of 232Th (228Ra-228Th) in sediments may then provide some quantitative assessment of the amount of material removed/re-deposited as well as some indications on the chronology of causal events. Examples from the Gulf of St. Lawrence (GSL) and the Pacific coastal rea of Mexico (PcM) are used to illustrate such isotopic responses to natural or anthropogenic disturbances. In the GSL relatively steady accumulation processes are usually observed, although sedimentary sequences show variable benthic mixing patterns over a large array of sedimentation rates (from mm/a to cm/a). In undisturbed sequences, 232Th-daughter isotopes in particulate matter show strong disequilibria due i) to 228Ra-diffusion/228Th adsorption in source-soils and during particulate transport, ii) 228Ra-behavior at the water column/sea-floor interface. Core-top sediments thus depict a strong excess in 228Th vs. 232Th. Below, a fast return (within ~ 10 a) of 228Th to equilibrium with its parent 228Ra leads to a 228Th deficit vs 232Th, in response to 228Ra-losses and diffusion towards the water column. Deeper, a return to full equilibrium conditions is observed (~ 30 a), but for "non-local mixing" events. Few disturbances are observed in the area. They include nearly cyclic pulses in 210Pb at the head of the Laurentian Trough, which we attribute to dredging operations of the St. Lawrence Sea-Way, and in the sealing of Hg-contaminated sediments in the Saguenay Fjord, by flood layers. Comparatively most sequences cored in estuarine settings of the PcM illustrate more critical situations with respect to the re-suspension of sediments, which are often contaminated due to land management and industrial practices

  15. Diagenesis in limestone-dolostone successions after 1 million years of rapid sea-level fluctuations: A case study from Grand Cayman, British West Indies

    Ren, Min; Jones, Brian


    Meteoric diagenesis in young marine carbonate sediments has commonly been linked to fluctuations in Quaternary glacio-eustatic sea levels. The extent to which these sea-level changes are recorded in these carbonate successions, however, remains questionable. This is amply demonstrated by the diagenetic record found in the limestones and dolostones of the Cayman Formation (Miocene) on the Cayman Islands. On the eastern part of Grand Cayman, dolomitization that ceased by 1 million years ago created an architecture whereby the limestones in the central part of the island were surrounded by dolostones in coastal areas of the island. Since then, the upper 90 m of the Cayman Formation has been repeatedly cycled through many different marine and meteoric diagenetic zones as large, rapid eustatic oscillations in sea level affected the island. The records of these diagenetic cycles in the dolostones and limestones are, however, different and impossible to match to the cyclic changes in sea level. In the peripheral dolostones, post-dolomitization diagenetic features are sparse. In contrast, the limestones in the interior of the island exhibit a wider variety of meteoric diagenetic features, including extensive dissolution and calcite cementation. The dolostones have low porosity (limestones are characterized by high porosity (up to 50%), especially in the lower and middle parts of the studied limestone succession. The different phases of diagenesis found in the limestones, however, cannot be specifically matched to any sea-level fluctuations that have affected these successions. This issue is further exemplified by the fact that that the last marine transgression over the last ~ 16,000 years ago appears to have left no tangible record. The analysis of this succession clearly demonstrates that not all diagenetic regimes will be recorded in the fabrics of limestones or dolostones.

  16. Sedimentology, conodonts and ostracods of the Devonian - Carboniferous strata of the Anseremme railway bridge section, Dinant Basin, Belgium

    Casier, J.-G.; Mamet, B.; Preat, A.; Sandberg, C.A.


    Seven major carbonate microfacies are defined in the Devonian - Carboniferous (D/C) strata (50 m) of the Anseremme railway bridge section, south of Dinant. They permit recognition of several levels encompassing the Etroeungt and Hastie??re formations. "Bathymetric" sequences range from open marine, below the storm wave base, to semi-restricted lagoon. This sequence records a shallowing-upward trend of the relative sea level, from environments below the storm wave base to strongly eroded supraticial pre-evaporitic environments. Faunal components (echinoderms, brachiopods...) indicate open-marine domain for the first six microfacies located within the dysphoticeuphotic zone in relatively shallow waters. The textures of the rocks (mudstones to rudstones) associated with lamination characteristics indicate the position of the storm (SWB) and the fair-weather (FWWB) wave bases. Microfacies seven suggests a semi-restricted platform with salinity fluctuations from hypersaline brines to brackish waters. Thus, the boundary of the Etroeungt/Hastie??re formations is marked by an abrupt drop in sea level. Carbonate micro-conglomerates recording an important erosive phase and a sedimentary hiatus. The environment is again open marine in the upper part of the Hastie??re Formation. Our conclusion is that the Anseremme section is not a reliable continuous succession for the study of the D/C boundary. This confirms the VAN STEENWINKEL (1988, 1993 hypothesis based on other arguments. Conodont faunas demonstrate that the Devonian sequence spans the five youngest conodont zones, but that two of these zones are not represented. The Epinette Formation is dated as the youngest part of the Middle expansa Zone. Thus, the boundary with the Late praesulcata Zone probably coincides with the sharp sedimentological change at the base of the Etroeungt Formation, which is interpreted to belong entirely to this zone. The disconformably overlying basal bed 159 of the Hastie??re Formation is dated

  17. Geoacoustic character, sedimentology and chronology of a cross-shelf Holocene sediment deposit off Cabo Frio, Brazil (southwest Atlantic Ocean)

    Mendoza, Ursula; Ayres Neto, Arthur; C. Abuchacra, Rodrigo; Fernandes Barbosa, Cátia; G. Figueiredo, Alberto; C. Gomes, Manoela; Belem, Andre L.; Capilla, Ramsés; S. Albuquerque, Ana Luiza


    The Cabo Frio region in the state of Rio de Janeiro, southeast coast of Brazil, is characterized by a local coastal upwelling system and converging littoral sediment transport systems that are deflected offshore at Cabo Frio, as a consequence of which a thick cross-shelf sediment deposit has developed over time. To investigate the evolution of this muddy deposit, geophysical, sedimentological and geochemical data from four sediment cores (3.8-4.1 m in length) recovered in water depths between 88 and 141 m were analyzed. The high-resolution seismic data show variable sediment thicknesses ranging from 1 to 20 m, comprising two sedimentary units separated by a high-impedance layer at a depth of about 10 m below the seafloor at the coring sites. According to the available age datings, the upper sedimentary unit is late Pleistocene to Holocene in age, whereas the lower unit (not dated) must, by implication, be entirely Pleistocene in age. The boomer-seismic reflection signal can be divided into three echo-types, namely transparent (inner shelf), stratified (middle shelf) and reflective (outer shelf), each type seemingly related to the local sediment composition. The upper 4 m of the upper sedimentary unit is dominated by silty sediment on the middle shelf, and by upward-fining sediments (silty sand to sandy silt) on the inner and outer shelf. The downcore trends of P-wave velocity, gamma-ray density and acoustic impedance are largely similar, but generally reversed to those of water and organic carbon contents. Total organic carbon contents increase with decreasing mean grain size, periodic fluctuations suggesting temporal changes in the regional hydrodynamics and primary productivity fuelled by the local upwelling system. The reconstruction of sedimentation rates in the course of the Holocene is based on 35 AMS age datings of organic material recovered from variable downcore depths. These range from a maximum of 13.3 cm/decade near the base of the inner shelf core (7

  18. Sedimentological and geochronological evidences of anthropogenic impacts on river basins in the Northern Latium coastal area (Italy)

    Piazzolla, Daniele; Paladini de Mendoza, Francesco; Scanu, Sergio; Marcelli, Marco


    In this work we aimed to compare sedimentological and geochronological data from three sediment core samples (MIG50, MRT50, and GRT50) taken in the Northern Latium (Italy) coastal area, at -50 m depth, to data regarding rainfall, river flows and the land use in the three most important hydrographic basins (Mignone, Marta and Fiora) and in the coastal area. Different trends of sediment mass accumulation rate (MAR) are detected in the three cores: a strongly increasing trend was identified in MIG50 and MRT50 cores while GRT50 doesn't show significant variation. Data from the sedimentological analysis of GRT50 core identify a progressive decrease in the sandy component, which declined from about 30% to the current level of 7% over the last 36 years, while MRT50 and MIG50 cores (mainly composed by pelitic fraction > 95%) showed slight variations of textural ratio between silt and clay. According to the general decrease of pluviometric trend observed in Italy, related to teleconnection pattern tendency (NAO), the statistical analysis of rain identified significative decrease only in the Fiora river basin, whereas in the other two locations the decrease was not as significant. Regarding the Fiora river flow, a significative decreasing trend of average flow is detected, while the flood regime remained unaffected over the past 30 years. The analysis of the land use shows that the human activities are increased of 6-10% over the available time steps (1990 - 2006) in Fiora and Mignone river basins, while the Marta river basin has a strong human impact since 1990 highligting more than 80% of artificial soil covering. The largest variation is observed on the Fiora basin (10%) where the antrhopic activities have expanded to an area of about 85 Km2. Moreover, in the last ten years a large beach nourishment in 2004 (570000 m3) and dredging activities in the early second half of 2000s (1000000 m3 moved) were performed in Marina di Tarquinia beach and in front of the Torrevaldaliga

  19. Late Quaternary Provenance and Flow Regime Reconstruction through Sedimentologic and Geochemical Evidence from the Bering/Chukchi Seas

    Pelto, B. M.; Brigham-Grette, J.; Kocis, J. J.; Petsch, S.


    The last 20 kyr have been marked by great changes in the Arctic, as the Laurentide Ice Sheet melted and led to the submergence of the Bering Land Bridge and the re-opening of the Bering Strait (BS). The BS is a narrow connection (about 85 km wide) between the Arctic and Pacific Oceans averaging less than 50 m in depth, with present-day flow of seawater northward through the BS, from the Pacific to the Arctic. This flow is of vital importance to global ocean circulation through its role in formation and stability of North Atlantic Deep Water (NADW). An open BS is believed to speed dispersal of North Atlantic freshwater anomalies, both by keeping thermohaline circulation strong, and through reversals of flow through the BS when the North Atlantic is hosed with freshwater. When the BS is closed, these anomalies cannot efficiently dissipate and thermohaline circulation is weakened, which is considered a factor in climate perturbations outside of orbital forcing. Given the period of flux and transition in the Arctic following the Last Glacial Maximum (LGM), the paleoceanographic history of the Bering and Chukchi Seas post-LGM, is important to an understanding of Arctic Ocean circulation, and consequent climate impacts. Today the Arctic is in a period of rapid change, multi-year sea ice is disappearing, and the continuation of climatic stability of the Holocene appears to be at an end. Comprehension of the functioning of the Arctic as a dynamic system is essential to predict future response of the system to change, such as seawater salinity-density changes, lowered sea and land albedo, and rising temperatures. Changes in BS throughflow intensity and direction during deglaciation and submergence of the Bering Land Bridge are proposed and supported in modeling simulations, and are thought to occur during millennial-scale climate changes. We have conducted a coupled sedimentological and geochemical investigation of a suite of marine sediment cores from the Bering and

  20. Sedimentological imprints of environmental variability at the Balkan Peninsula on the sediment sequence of Lake Ohrid (Macedonia, Albania) between the Mid Pleistocene Transition and present days: The ICDP SCOPSCO project

    Francke, Alexander; Wagner, Bernd; Leicher, Niklas; Raphael, Gromig; Leng, Melanie; Lacey, Jack; Vogel, Hendrik; Baumgarten, Henrike; Thomas, Wonik; Zanchetta, Giovanni; Roberto, Sulpizio; Krastel, Sebastian; Lindhorst, Katja


    The UNESCO World Heritage site of Lake Ohrid in the Balkans is thought to be the oldest, continuously existing lake in Europe. In order to unravel the geological and evolutionary history of the lake, a deep drilling campaign was conducted in spring 2013 under the umbrella of the ICDP SCOPSCO project. At the coring site "DEEP" in central parts of the lake, more than 1,500 m of sediments were recovered down to a penetration depth of 569 m blf. This sediment sequence is assumed to be more than 1.2 Ma old and likely covers the entire lacustrine deposits of the Lake Ohrid Basin. Currently, an age model for the upper 260m of the DEEP- site sequence is available. This age model is based on chronological tie points (tephrochronology), and wiggle matching of down hole logging data and (bio-)geochemistry data (XRF, TIC, TOC) from the core sequence to the global benthic stack LR04 and local insolation patterns. The data suggests that the upper 260 m of the DEEP-site sequence corresponds to the time period between the Mid Pleistocene Transition (MPT) and present days. During this period, the sedimentological properties of the sediments show a strong dependency on environmental variability in the area. Interglacial deposits appear massive or marbled, contain up to 80 % of CaCO3 (high TIC), high amounts of organic matter (high TOC) and biogenic silica (high BSi), and low contents of clastic material. Glacial deposits are predominantly marbled and calcite is generally absent. Similarly, the amounts of organic matter and biogenic silica are low, and glacial sediments predominately consist of clastic matter. Distinct layers of siderite and uniformly distributed Fe- or Mn- oxides occur in the glacial deposits, vivianite concretions occur in both the glacial and interglacial periods. High CaCO3 contents in deposits formed during warm (interglacial) periods are also known from studies on short pilot cores from Lake Ohrid and are triggered by increased productivity in the lake, such as

  1. A carbon isotopic and sedimentological record of the latest Devonian (Famennian) from the Western U.S. and Germany

    Myrow, P.M.; Strauss, J.V.; Creveling, J.R.; Sicard, K.R.; Ripperdan, R.; Sandberg, C.A.; Hartenfels, S.


    New carbon isotopic data from upper Famennian deposits in the western United States reveal two previously unrecognized major positive isotopic excursions. The first is an abrupt ~. 3??? positive excursion, herein referred to as ALFIE (A Late Famennian Isotopic Excursion), recorded in two sections of the Pinyon Peak Limestone of north-central Utah. Integration of detailed chemostratigraphic and biostratigraphic data suggests that ALFIE is the Laurentian record of the Dasberg Event, which has been linked to transgression in Europe and Morocco. Sedimentological data from the Chaffee Group of western Colorado also record transgression at a similar biostratigraphic position, with a shift from restricted to open-marine lithofacies. ALFIE is not evident in chemostratigraphic data from age-equivalent strata in Germany studied herein and in southern Europe, either because it is a uniquely North American phenomenon, or because the German sections are too condensed relative to those in Laurentia. A second positive carbon isotopic excursion from the upper Chaffee Group of Colorado is recorded in transgressive strata deposited directly above a previously unrecognized paleokarst interval. The age of this excursion, and the duration of the associated paleokarst hiatus, are not well constrained, although the events occurred sometime after the Late Famennian Middle expansa Zone. The high positive values recorded in this excursion are consistent with those associated with the youngest Famennian Middle to Late praesulcata Hangenberg Isotopic Excursion in Europe, the isotopic expression of the Hangenberg Event, which included mass extinction, widespread black shale deposition, and a glacio-eustatic fall and rise. If correct, this would considerably revise the age of the Upper Chaffee Group strata of western Colorado. ?? 2011 Elsevier B.V.

  2. Sedimentology and Stratigraphy Architecture of the late Pleistocene-Holocene Succession of the Gargaresh Formation, Subratah Basin, NW Libya

    Hlal, Osama; Bennur, Sami


    Gargaresh Formation outcrops is comprises the outcrops between the Misurata (N32o22'18'' E15o12'03'') to the Tripoli(N32o 51'10'' E13o 03'22'') areas is represented by prominent carbonate aeolianite exposed in extensive outcrops along the NW Libyan shoreline. Gargaresh Formation outcrops comprises two Members an upper Kaam Member of Aeolian origin and a lower Karrot Member of marine origin. The study of the Gargaresh Formation can provide useful information on reconstructions of Late Pleistocene-Holocene history of NW Libya and new insights on palaeogeography. It is forming low ridges and cliffs along the coastline of NW Libya and occurs as cliffs continuously attached to the sea tide, and occasionally interrupted by broad wadis or deep-cut embayment. The Gargaresh Formation sediments are dominated by calcarenites with skeletal marine fauna and non-skeletal grains of lithoclasts, aggregate, with oolites. In addition, these rocks are characterized by very well aeolian controlling factors represented by wind blown sediments such as large scale cross lamination (aeolianite) . The majority of palaeocurrent direction was to SE, on the other hand the dune migration was SE also. The sediments of Gargaresh Formation outcrops from Misurata to Tripoli NW Libya mostly allochthonous except the paleosols red-brown unit. Most of its fossils are thanatoconoses. Gargaresh Formation sediments shows that the original aragonite composition of pelecypoda and gastropods fragments are mostly preserved, but partly transformed into granular calcite as pendulous (meniscus) cement texture in response to meteoric fresh-water. Keywords: Sedimentology; Stratigraphic architecture; Aeolian origin; marine origin; Calcarenites; Late Pleistocene-Holocene


    Lauren P. Birgenheier; Michael D. Vanden Berg,


    An integrated detailed sedimentologic, stratigraphic, and geochemical study of Utah's Green River Formation has found that Lake Uinta evolved in three phases (1) a freshwater rising lake phase below the Mahogany zone, (2) an anoxic deep lake phase above the base of the Mahogany zone and (3) a hypersaline lake phase within the middle and upper R-8. This long term lake evolution was driven by tectonic basin development and the balance of sediment and water fill with the neighboring basins, as postulated by models developed from the Greater Green River Basin by Carroll and Bohacs (1999). Early Eocene abrupt global-warming events may have had significant control on deposition through the amount of sediment production and deposition rates, such that lean zones below the Mahogany zone record hyperthermal events and rich zones record periods between hyperthermals. This type of climatic control on short-term and long-term lake evolution and deposition has been previously overlooked. This geologic history contains key points relevant to oil shale development and engineering design including: (1) Stratigraphic changes in oil shale quality and composition are systematic and can be related to spatial and temporal changes in the depositional environment and basin dynamics. (2) The inorganic mineral matrix of oil shale units changes significantly from clay mineral/dolomite dominated to calcite above the base of the Mahogany zone. This variation may result in significant differences in pyrolysis products and geomechanical properties relevant to development and should be incorporated into engineering experiments. (3) This study includes a region in the Uinta Basin that would be highly prospective for application of in-situ production techniques. Stratigraphic targets for in-situ recovery techniques should extend above and below the Mahogany zone and include the upper R-6 and lower R-8.

  4. Core Description and a Preliminarily Sedimentology Study of Site 1202D, Leg 195, in the Southern Okinawa Trough

    Chi-Yue Huang


    Full Text Available ODP Site 1202 of Leg 195 was designed primarily for a high-resolution study of the paleoceanography of the Kuroshio Current in the southern Okinawa Trough off NE Taiwan. Four holes were drilled in which Hole 1202D is described in detail in this study for an assessment of core quality for paleoceanography study and understanding of sedimentological features, especially turbidite sedimentation and the sediment provenances during the Late Quaternary in the southern Okinawa Trough. Pelagic mud with insignificant silt or sand layers is observed from the core top down to 133 m (mbsf; Marine Isotope Stages 1-3, but the silt-sand layer ratio (SLR: total thickness of silt and sand layers / 1.5 m of core increases gradually from a value of 50 % between 223 and 279 m, followed by decreases to values 250 _ Slate fragments are commonly found in fine-grained turbidite dominant intervals (160 - 280 m, while mica flakes can be observed in the muds throughout the core. The major detrital components were derived primarily from the Miocene slate belt of the pre-collision accretionary prism of the Central Range in northern Taiwan. The occurrence of volcanics could represent submarine volcanic activity in the active-opening Okinawa Trough back-arc basin off NE Taiwan. Shallow-marine fossils including benthic foraminifers, echinoids, bryozoans and mollusks are also found in the fine-grained turbidite dominant intervals. These fossil assemblages could have been deposited in the shallow shelf and then transported to the depositional site along with voluminous terrigenous materials derived from Taiwan, via submarine channels or by slope failures due to frequent earthquakes induced by plate convergence/collision and extension in the southwestern Okinawa Trough off NE Taiwan. It is concluded that the top 133 m of the core is better suited for paleoceanographic reconstruction.

  5. Sedimentology, eruptive mechanism and facies architecture of basaltic scoria cones from the Auckland Volcanic Field (New Zealand)

    Kereszturi, Gábor; Németh, Károly


    Scoria cones are a common type of basaltic to andesitic small-volume volcanoes (e.g. 10- 1-10- 5 km3) that results from gas-bubble driven explosive eruptive styles. Although they are small in volume, they can produce complex eruptions, involving multiple eruptive styles. Eight scoria cones from the Quaternary Auckland Volcanic Field in New Zealand were selected to define the eruptive style variability from their volcanic facies architecture. The reconstruction of their eruptive and pyroclastic transport mechanisms was established on the basis of study of their volcanic sedimentology, stratigraphy, and measurement of their pyroclast density, porosity, Scanning Electron Microscopy, 2D particle morphology analysis and Visible and Near Visible Infrared Spectroscopy. Collection of these data allowed defining three end-member types of scoria cones inferred to be constructed from lava-fountaining, transitional fountaining and Strombolian type, and explosive Strombolian type. Using the physical and field-based characteristics of scoriaceous samples a simple generalised facies model of basaltic scoria cones for the AVF is developed that can be extended to other scoria cones elsewhere. The typical AVF scoria cone has an initial phreatomagmatic phases that might reduce the volume of magma available for subsequent scoria cone forming eruptions. This inferred to have the main reason to have decreased cone volumes recognised from Auckland in comparison to other volcanic fields evolved dominantly in dry eruptive condition (e.g. no external water influence). It suggests that such subtle eruptive style variations through a scoria cone evolution need to be integrated into the hazard assessment of a potentially active volcanic field such as that in Auckland.

  6. Transition of microbiological and sedimentological features associated with the geochemical gradient in a travertine mound in northern Sumatra, Indonesia

    Sugihara, Chiya; Yanagawa, Katsunori; Okumura, Tomoyo; Takashima, Chizuru; Harijoko, Agung; Kano, Akihiro


    Modern travertines, carbonate deposits in Ca-rich hydrothermal water with high pCO2, often display a changing environment along the water path, with corresponding variability in the microbial communities. We investigated a travertine-bearing hot spring at the Blue Pool in northern Sumatra, Indonesia. The thermal water of 62 °C with high H2S (200 μM) and pCO2 ( 1 atm) developed a travertine mound 70 m wide. The concentrations of the gas components H2S and CO2, decrease immediately after the water is discharged, while the dissolved oxygen, pH, and aragonite saturation increase in the downstream direction. Responding to the geochemical gradient in the water, the surface biofilms change color from white to pink, light-green, dark-green, and brown as the water flows from the vent; this corresponds to microbial communities characterized by chemolithoautotrophs (Halothiobacillaceae), purple sulfur bacteria (Chromatiaceae), Anaerolineaceae, and co-occurrence of green non-sulfur bacteria (Chloroflexales)-Cyanobacteria, and green sulfur bacteria (Chlorobiales), respectively. In an environment with a certain level of H2S (> 1 μM), sulfur digestion and anoxygenic photosynthesis can be more profitable than oxygenic photosynthesis by Cyanobacteria. The precipitated carbonate mineral consists of aragonite and calcite, with the proportion of aragonite increasing downstream due to the larger Mg2 +/Ca2 + ratio in the water or the development of thicker biofilm. Where the biofilm is well developed, the aragonite travertines often exhibit laminated structures that were likely associated with the daily metabolism of these bacteria. The microbiological and sedimentological features at the Blue Pool may be the modern analogs of geomicrobiological products in the early Earth. Biofilm of anoxygenic photosynthetic bacteria had the potential to form ancient stromatolites that existed before the appearance of cyanobacteria.

  7. Crime scene investigation involving a large turbidite - a 1h-teaching unit in Limnogeology/Sedimentology

    Gilli, Adrian; Kremer, Katrina


    In 1996, a dead corpse (named „Brienzi") was found at the banks of the picturesque Lake Brienz in the Bernese Alps/Switzerland. What is the origin of this corpse and which chain of events lead to this crime scene? This is the starting position for a 1h exercise/game for undergraduate students in Earth Sciences/Geosciences.The students are provided with a wealth of evidences like statements from people potentially involved in the case, age data on the human corpse and monitoring data from the lake and its surroundings. The students are guided through the game step by step. After solving a task, the students get a feedback and can check if they were correct with their interpretation. Interestingly for earth science students, a lacustrine mass moment plays an important role in these investigations, but more should not be given at this point. In this exercise, we can also check if the teached content of the previous lessons have been acquired correctly by the students, as it deals with diverse limnogeological and sedimentological aspects. The game is strongly based on a study of Girardclos et al. (2007) and uses their argumentation for the occurrence of a large mass movement in Lake Brienz in 1996. A copy of the game is available by the author upon request. Reference: Girardclos, S., Schmidt, O.T., Sturm, M., Ariztegui, D., Pugin, A. and Anselmetti, F.S., 2007, The 1996 AD delta collapse and large turbidite in Lake Brienz. Marine Geology, 241, pp.137-154. doi:10.1016/j.margeo.2007.03.011

  8. Sedimentology and preservation of aeolian sediments on steep terrains: Incipient sand ramps on the Atacama coast (northern Chile)

    Ventra, Dario; Rodríguez-López, Juan Pedro; de Boer, Poppe L.


    The origin of topographically controlled aeolian landforms in high-relief settings is difficult to synthesize under general models, given the dependence of such accumulations on local morphology. Quaternary sand ramps have been linked to palaeoclimate, regional geomorphology and wind patterns; however, controls on the early development and preservation of such landforms are poorly known. This study describes the morphology and sedimentology of complex sedimentary aprons along steep coastal slopes in the Atacama Desert (Chile). Direct slope accessibility and continuous stratigraphic exposures enable comparisons between active processes and stratigraphic signatures. Stratigraphic facies distribution and its links with patterns of aeolian deposition show that the preservation of wind-laid sediments depends on the morphology and processes of specific slope sectors. The spatial organization of runoff depends on bedrock configuration and directly controls the permanence or erosion of aeolian sediment. The occurrence of either water or mass flows depends on the role of aeolian fines in the rheology of flash floods. In turn, the establishment of a rugged surface topography controlled by patterns of mass-flow deposition creates local accommodation for aeolian fines, sustaining the initial aggradation of a colluvial-aeolian system. By contrast, slopes subject to runoff develop a thin, extensive aeolian mantle whose featureless surface is subject mostly to sediment bypass down- and across-slope; the corresponding stratigraphic record comprises almost exclusively thin debris-flow and sheetflood deposits. Slope morphology and processes are fundamental in promoting or inhibiting aeolian aggradation in mountain settings. Long-term sand-ramp construction depends on climate and regional topography, but the initial development is probably controlled by local geomorphic factors. The observed interactions between wind and topography in the study area may also represent a process

  9. Integrated Sedimentological Approach to Assess Reservoir Quality and Architecture of Khuff Carbonates: Outcrop Analog, Central Saudi Arabia

    Osman, Mutsim; Abdullatif, Osman


    The Permian to Triassic Khuff carbonate reservoirs (and equivalents) in the Middle East are estimated to contain about 38.4% of the world's natural gas reserves. Excellent exposed outcrops in central Saudi Arabia provide good outcrop equivalents to subsurface Khuff reservoirs. This study conduct high resolution outcrop scale investigations on an analog reservoir for upper Khartam of Khuff Formation. The main objective is to reconstruct litho- and chemo- stratigraphic outcrop analog model that may serve to characterize reservoir high resolution (interwell) heterogeneity, continuity and architecture. Given the fact of the limitation of subsurface data and toolsin capturing interwell reservoir heterogeneity, which in turn increases the value of this study.The methods applied integrate sedimentological, stratigraphic petrographic, petrophysical data and chemical analyses for major, trace and rare earth elements. In addition, laser scanning survey (LIDAR) was also utilized in this study. The results of the stratigraphic investigations revealed that the lithofacies range from mudstone, wackestone, packestone and grainstone. These lithofacies represent environments ranging from supratidal, intertidal, subtidal and shoal complex. Several meter-scale and less high resolution sequences and composite sequences within 4th and 5th order cycles were also recognized in the outcrop analog. The lithofacies and architectural analysis revealed several vertically and laterally stacked sequences at the outcrop as revealed from the stratigraphic sections and the lidar scan. Chemostratigraphy is effective in identifying lithofacies and sequences within the outcrop analog. Moreover, different chemical signatures were also recognized and allowed establishing and correlating high resolution lithofacies, reservoir zones, layers and surfaces bounding reservoirs and non-reservoir zones at scale of meters or less. The results of this high resolution outcrop analog study might help to understand

  10. Geomorphological and sedimentological characteristics of cyclone-generated landforms and washover deposits along the coasts of NW Australia

    May, Simon Matthias; Engel, Max; Brückner, Helmut; Pint, Anna; Kelletat, Dieter; Scheffers, Anja; Squire, Peter


    (tsunamis, cyclone landfalls) of W Australia. Main challenges include dating (14C, OSL) and distinguishing between event and non-event processes, and between event types, based on sedimentology, microfauna, and shell taphonomy.

  11. The roles of organic matter in the formation of uranium deposits in sedimentary rocks

    Spirakis, C.S.


    Because reduced uranium species have a much smaller solubility than oxidized uranium species and because of the strong association of organic matter (a powerful reductant) with many uranium ores, reduction has long been considered to be the precipitation mechanism for many types of uranium deposits. Organic matter may also be involved in the alterations in and around tabular uranium deposits, including dolomite precipitation, formation of silicified layers, iron-titanium oxide destruction, dissolution of quartz grains, and precipitation of clay minerals. The diagenetic processes that produced these alterations also consumed organic matter. Consequently, those tabular deposits that underwent the more advanced stages of diagenesis, including methanogenesis and organic acid generation, display the greatest range of alterations and contain the smallest amount of organic matter. Because of certain similarities between tabular uranium deposits and Precambrian unconformity-related deposits, some of the same processes might have been involved in the genesis of Precambrian unconformity-related deposits. Hydrologic studies place important constraints on genetic models of various types of uranium deposits. In roll-front deposits, oxidized waters carried uranium to reductants (organic matter and pyrite derived from sulfate reduction by organic matter). After these reductants were oxidized at any point in the host sandstone, uranium minerals were reoxidized and transported further down the flow path to react with additional reductants. In this manner, the uranium ore migrated through the sandstone at a rate slower than the mineralizing ground water. In the case of tabular uranium deposits, the recharge of surface water into the ground water during flooding of lakes carried soluble humic material to the water table or to an interface where humate precipitated in tabular layers. These humate layers then established the chemical conditions for mineralization and related

  12. Matter and twin matter in bimetric MOND

    Milgrom, Mordehai


    Bimetric MOND (BIMOND) theories, propounded recently, predict peculiar gravitational interactions between matter and twin matter (TM). Twin matter is hypothetical matter that might couple directly only to the second metric of the theory. Considerations of cosmology in the BIMOND framework suggest that such TM might exist and copy matter in its attributes. Here I investigate the indirect interactions that BIMOND theories predict between nonrelativistic masses of matter and TM. The most salient result is that in the deep-MOND regime of the matter-TM-symmetric theories, TM behaves as if it has a negative gravitational mass. To wit, interaction within each sector is attractive MOND gravity, but between matter and TM it is repulsive MOND gravity. In the high-acceleration regime, the interaction depends on a parameter, beta. For the favored value beta=1, matter and TM do not interact in this regime; for beta1 they repel each other. Such interactions may have substantial ramifications for all aspects of structure fo...

  13. Combustion of nuclear matter into strange matter

    Lugones, G. (Departamento di Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, (1900) La Plata (Argentina)); Benvenuto, O.G.; Vucetich, H. (Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, (1900) La Plata (Argentina))


    We study the properties of the combustion of pure neutron matter into strange matter in the framework of relativistic hydrodynamical theory of combustion. Because of the uncertainties in the actual properties of neutron matter, we employ the free neutron, Bethe-Johnson, Lattimer-Ravenhall, and Walecka equations of state and for strange matter we adopt the MIT bag model approximation. We find that combustion is possible for free neutron, Bethe-Johnson, and Lattimer-Ravenhall neutron matter but not for Walecka neutron matter. We interpret these results using a simple polytropic approximation showing that there exists a general flammability condition. We also study the burning of neutron matter into strange matter in a pipe showing that hydrodynamics demands flames faster than predicted by kinetics by several orders of magnitude, implying that the flame must be turbulent. Also the conditions for the deflagration to detonation transition are addressed, showing that in a pipe some of them are satisfied, strongly suggesting that the actual combustion mode should be detonation.

  14. Seasonal variations of coastal sedimentary trace metals cycling: insight on the effect of manganese and iron (oxy)hydroxides, sulphide and organic matter.

    Dang, Duc Huy; Lenoble, Véronique; Durrieu, Gaël; Omanović, Dario; Mullot, Jean-Ulrich; Mounier, Stéphane; Garnier, Cédric


    The combination of analysis, multivariate treatment (PCA) and chemical speciation calculation confirmed the control of Fe, Mn, sulphide and organic matter on metals dynamics in coastal sediments (0-5 cm surface sediments and sediments cores) of Toulon Bay (NW Mediterranean). The temporal monitoring of the physic-chemical parameters as well as the dissolved/particulate minor (Fe/Mn) and trace elements (i.e. Ag, Cd, Co, Cu, Ni, Pb, Zn, …) concentrations in porewaters and sediments were assessed. Multivariate treatment revealed different behaviours for marine elements, terrestrial ones and contaminants. Seasonal variations of metals mobilization in porewater were observed, related to diagenesis activity. Element mobility was studied by selective extractions (ascorbate, acid and alkaline) on sediments. Thermodynamic simulation (PHREEQC) was performed to calculate the elemental dissolved speciation, the mineral saturation index and then to simulate the solid/liquid interaction through precipitation processes, studying the contrasted influence of dissolved organic matter and sulphide.

  15. Coral Patch seamount (NE Atlantic – a sedimentological and megafaunal reconnaissance based on video and hydroacoustic surveys

    C. Wienberg


    Full Text Available The present study provides new knowledge about the so far largely unexplored Coral Patch seamount which is located in the NE Atlantic Ocean half-way between the Iberian Peninsula and Madeira. For the first time a detailed hydroacoustic mapping (MBES in conjunction with video surveys (ROV, camera sled were performed to describe the sedimentological and biological characteristics of this sub-elliptical ENE-WSW elongated seamount. Video observations were restricted to the southwestern summit area of Coral Patch seamount (water depth: 560–760 m and revealed that this part of the summit is dominated by exposed hard substrate, whereas soft sediment is just a minor substrate component. Although exposed hardgrounds are dominant for this summit area and, thus, offer suitable habitat for settlement by benthic organisms, the benthic megafauna shows rather scarce occurrence. In particular, scleractinian framework-building cold-water corals are apparently rare with very few isolated and small-sized live occurrences of the species Lophelia pertusa and Madrepora oculata. In contrast, dead coral framework and coral rubble are more frequent pointing to a higher abundance of cold-water corals on Coral Patch during the recent past. This is even supported by the observation of fishing lines that got entangled with rather fresh-looking coral frameworks. Overall, long lines and various species of commercially important fish were frequently observed emphasising the potential of Coral Patch as an important target for fisheries that may have impacted the entire benthic community. Hydroacoustic seabed classification covered the entire summit of Coral Patch and its northern and southern flanks (water depth: 560–2660 m and revealed extended areas dominated by mixed and soft sediments at the northern flank and to a minor degree at its easternmost summit and southern flank. Nevertheless, these data also predict most of the summit area to be dominated by exposed bedrock

  16. Coral Patch seamount (NE Atlantic – a sedimentological and macrofaunal reconnaissance based on video and hydroacoustic surveys

    C. Wienberg


    Full Text Available The present study provides new knowledge about the so far largely unexplored Coral Patch seamount which is located in the NE Atlantic Ocean half-way between the Iberian Peninsula and Madeira. For the first time a detailed hydroacoustic mapping (MBES in conjunction with video surveys (ROV, camera sled were performed to describe the sedimentological and biological characteristics of this sub-elliptical ENE-WSW elongated seamount. Video observations were restricted to the south-western summit area of Coral Patch seamount (area: ~ 8 km2, water depth: 560–760 m and revealed that this part of the summit is dominated by exposed hard substrate, whereas soft sediment is just a minor substrate component. Although exposed hardgrounds are dominant for this summit area, and thus, offer suitable habitat for settlement by benthic organisms, the macrofauna shows rather low abundance and diversity. In particular, scleractinian framework-building cold-water corals are apparently rare with very few isolated and small-sized live occurrences of the species Lophelia pertusa and Madrepora oculata. In contrast, dead coral framework and coral rubble are more frequent pointing to a higher abundance of cold-water corals on Coral Patch during the recent past. This is even supported by the observation of fishing lines that got entangled with rather fresh-looking coral frameworks. Overall, long lines and various species of commercially important fish were frequently observed emphasising the potential of Coral Patch as an important target for fisheries that may have impacted the entire benthic community. Hydroacoustic seabed classification covered the entire summit of Coral Patch and its northern and southern flanks (area: 560 km2; water depth: 560–2660 m and revealed extended areas dominated by mixed and soft sediments at the northern flank and to a minor degree at its easternmost summit and southern flank. Nevertheless, also these

  17. Sedimentological evidence for a deforming bed in a late Pleistocene glacial sequence from ANDRILL AND-1B, Ross Sea, Antarctica

    Cowan, E. A.; Powell, R. D.


    A 1,284.87m-long sediment core (AND-1B) was drilled from beneath the McMurdo Ice Shelf sector of the Ross Ice Shelf as part of the Antarctic geological drilling program, ANDRILL. Snapshots of diamictite depositional processes and paleoenvironmental conditions have been interpreted from a nested set of samples collected at overlapping scales of observation. Data used for detailed sedimentological analyses include cm-scale core logging based on x-radiographs of the archive halves in addition to the original core description, bulk samples, and oriented 45 x 70mm thin sections of diamictites for micromorphology analysis. The 5.8m-thick interval studied contains a complete glacial advance-retreat sequence that is bracketed by glacial surfaces of erosion (GSE) at 41.9 and 47.7mbsf recording glacial advance over the core site. 4.6m of subglacial till is deposited above the lower GSE represented by a sequence of thin muddy conglomerate with diverse pebble lithologies, massive clast-rich muddy diamicite, and stratified diamictite with clast-rich and clast-free beds. The sand size fraction of bulk samples and thin sections from the till are dominated by aggregate grains, termed till pellets following terminology used by sedimentologists in the Ross Sea. The core of the pellet may be a lithic grain or stiff till with additional clay plastered on the outside forming rounded grains from angular ones. Till pellets are rounded, spherical to prolate in form and are associated with turbate structures and aligned grains in till thin sections - evidence of rotational deformation. The area beneath an ice shelf in front of a grounding line is recorded by a thin bed of granular particles that transitions to silty claystone stratified with granules. Granular layers are thought to be from periodic winnowing by strong currents focused near the grounding line. The sub-ice shelf transition from proximal grounding line to distal is recorded by a gradational contact between stratified silty

  18. Evolution of Çan-Etili (Çanakkale-NW Turkey) lignite basin:Sedimentology, petrology, palynology and lignite characterization

    Mustafa Bozcu; Funda Akgün; Gülbin Gürdal; Ayşe Bozcu; Sevinç Kapan Yeşilyurt; Öznur Karaca; M. Serkan Akkiraz


    abstract This study examines the development and sedimentology of Çan-Etili lignite basin in Biga Peninsula (NW Turkey) along with the palynologic and petrographic properties of the coals in this region. The Çan-Etili lignite basin discordantly overlies Oligocene-aged Çan volcanics. The basin consists of caldera type sedimentation developed by the combined effects of volcanism and tectonics. The volcanic rocks forming the basement of the basin consist of andesitic, dacitic and basaltic lava flows as well as agglomerates, tuff and silicified tuffs, and kaolin which is their alteration product. The basement volcanic rocks cooled from high potassium and calc-alkaline magma. The trace element geochemistry of different rocks within the volcanics reveals that they are from a volcanic arc. The Çan Formation contains lignites and consists of 6 lithofacies representing alluvial, fluvial, marsh and lacustrine environments. These lithofacies are the lower volcanogenic conglomerate, the claystone, the lignite, the laminated organic claystone, the tuff intercalated sandstone–siltstone and the upper volcanogenic conglomerate. The lignite in the basin is limnic and is formed in a non-fluvial marsh and marsh-lake environment. An abundant percentage of vegetation (Engelhardia, Sapotaceae, Cyrillaceae) is compatible with temperate and subtropical climatic conditions in the basin during sedimentation of lignite.The coals of Çan-Etili basin are humic with high sulfur content (6–6.5%average) mostly containing huminite compounds belonging to the class of lignite-low bituminous (C-A) coal. Their coalification rank is between 0.38%and 0.56%Ro. The coals are formed in limnic-limnotelmatic marsh zones based on their microlithotype components. The inorganic components of the coal mostly consist of pyrite and clay. The trace elements, As, Th, U and V, are higher than international coal standards. The coal quality is adversely affected by high sulfur content and sulfur driven trace

  19. Sedimentological and Geophysical Signatures of a Relict Tidal Inlet along a Wave-Dominated Barrier, Assateague Island, Maryland, USA

    Seminack, C. T.; Buynevich, I. V.; Grimes, Z. T.; Griffis, N.; Goble, R. J.


    of beach ridges have developed across the Green Run Bay segment and exhibit signatures of storm erosion in shore-normal GPR profiles. This punctuated barrier progradation took place during the historical period, with optical dates of beach ridge and dune generations ranging from AD 1680 to 1920. Our study demonstrates the need for integrating geomorphological, geophysical, sedimentological, and chronological databases to reconstruct the geological legacy of a relict inlet channel along a wave-dominated barrier coast.

  20. Lake Towuti, Indonesia: First Sedimentological Results of a New Surface Sediment Study during the Icdp-Tdp Campaign 2015

    Hasberg, A. K.; Melles, M.; Vogel, H.; Russel, J.; Bijaksana, S.


    A. HASBERG1, M. MELLES1, H. VOGEL2, J. RUSSEL3, S. BIJAKSANA4 and all ICDP field campaign participations 1Institute for Geology and Mineralogy, University of Cologne, Zülpicher Str. 49a, 50974 Cologne, Germany, email: 2Department for Geology, University Bern, Switzerland3Department of Geology, Brown University, USA 4Faculty of Mining and Petroleum Engineering, Institute Teknologi Bandung, Indonesia Lake Towuti (2.75°S, 121.5°E), the largest tectonically formed lake (surface area: 561 km²) of the Republic Indonesia, is located in Central Sulawesi. The lake has a high, unique, Fe-reducing bacterial biodiversity and it has an important relevance to evolutionary biology through its location. Furthermore it is part of the Malili lake system, which consists of five lakes. The three largest of these, Matano, Mahalona and Towuti, are connected through a surface outflow today, but the linkage may not have always existed during the past, as indicated by the high level of endemism in each lake and the active tectonic movement of the 'Matano Fault system'. In summer 2015 the ICDP-funded Towuti Drilling Project (TDP) was conducted at Lake Towuti and recovered over 1000 meters of new sediment core. Within the scope of the TDP, lake surface sediments were also collected to investigate the modern terrestrial climate and aquatic environmental conditions, as well as the major sediment input sources from the catchment area. We collected a 1 to 4 km high-resolution grid of 84 surface samples from Lake Towuti and five samples from the Mahalona River, which links the Malili Lakes. These 89 surface samples were analyzed by various, sedimentological methods including smear-slide microscopy, coarse-fraction analyses, grain-size analysis, XRF-powder, and CNS measurements. The results will help to understand the interaction between the present-day lake sedimentation, hydrological and climatic conditions and to evaluate these as proxies for the hydrological

  1. The aeolian sedimentary system in the northern Qilian Shan and Hexi Corridor (N-China) - geomorphologic, sedimentologic and climatic drivers

    Nottebaum, Veit; Lehmkuhl, Frank; Stauch, Georg


    The formation of aeolian deposits depends on the influence of climatic factors but also on non-climatic controls, such as local geomorphological setting and tectonic activity. Unravelling the environmental history needs a careful consideration of a set of sections to capture spatial variability and a detailed investigation of depositing processes and chronology. Along the northern margin of the Qilian Shan mountain range 22 OSL-dated loess and aeolian sand sections and additional surface samples reveal the interactions between climatic, geomorphologic and sedimentologic factors. Thin loess covers (~1-2 m) occur in elevations of 2000 to 3800 m asl, which were mainly accumulated during the Holocene. End-member modelling of loess grain size data exhibits three dominant aeolian transport pathways representing local transport from fluvial storages, dust storm contribution and background dust deposition. Their relative contributions show a clear dependence on geomorphological setting, and additionally, synchronous trends throughout the Holocene. Their relative changes allow conclusions about Holocene environmental conditions. Discontinuous archives (aeolian sand, lacustrine, and alluvial deposition) in the lower forelands of the Qilian Shan show a distinct spatial pattern contrasting western and eastern forelands. The comparison of OSL ages exhibits high sediment accumulation (~2 m/ka) in the drier western part during the Late Glacial, while the lack of Holocene ages indicates sediment discharge / deflation. In contrast, moister areas in the eastern foreland yield scattered Holocene ages. This indicates high sediment dynamics, benefiting from fluvial reworking and thus provided sediment availability. Fluvial sediment supply plays an important role in sediment recycling. Meanwhile, western forelands lack efficient sand sources and fluvial reworking agents. The study exemplifies the complex sedimentary systems acting along mountain to foreland transects which often host

  2. Missing evidence for the LGM-asynchronity in the Central Spanish Pyrenees in geomorphological, sedimentological and pedological archives

    Hirsch, Florian; Raab, Thomas


    According to the state of knowledge, the glacial advances in the Eastern Pyrenees were synchronous with the global LGM during the Late Pleistocene (MIS 2), but the glacial advances in the Central Spanish Pyrenees at MIS 3 were asynchron with the global LGM. Whereas in the Eastern Pyrenees the glacial advances are dated in several well agreeing studies by surface exposure dating of boulders from lateral or terminal moraines, the asynchronity of the Central Spanish Pyrenees was postulated mainly by OSL dating on glacial and fluvial sediments and on radiocarbon dating of pollen from lacustrine deposits. The time difference of about 15 ka raises the question if this is a result of (local) climate factors or owed to failures caused by using several dating techniques on different archives. Anyway, if this time lag is correct, post-LGM formation of soils and sediments from the Late Pleistocene should be different between the Eastern Pyrenees and the Central Spanish Pyrenees. We therefore applied a combined approach of geomorphological, sedimentological and pedological investigations to reconstruct the Late Quaternary landscape development in the Aragon- and Gallego Valley of the Central Spanish Pyrenees. Our study reveals that in both valleys the Pre-Holocene geomorphodynamics on the lateglacial deposits show clear analogies with findings from Pleistocene periglacial landscapes in Central Europe. For MIS 4 and early MIS 3 periglacial processes are proven by loess deposition and formation of solifluction sediments. The glacial sediments, which were dated in earlier studies into mid MIS 3 and counted so far as prove for the asynchronous LGM of the Central Spanish Pyrenees, are covered by periglacial deposits of lateglacial age (14 ka to 11 ka). Surprisingly neither the glacial sediments have pedogenic features that indicate lateglacial soil development, nor do the periglacial deposits show indications for lateglacial soil erosion. Therefore we conclude that soil formation

  3. Sedimentology and ichnology of the fluvial reach to inner estuary of the Ogeechee River estuary, Georgia, USA

    Shchepetkina, Alina; Gingras, Murray K.; Pemberton, S. George


    Through the integration of sedimentological and ichnological observations, this paper explores the character of sediments deposited across the fluvio-tidal transition zone of the upper microtidal, mixed-energy, sand-dominated Ogeechee River estuary, Georgia, USA. A transect of tidally influenced to fluvial channel-bars and their facies variability is reported. Field and laboratory methods were employed, including observation of physical and biogenic sedimentary structures on the point-bar surfaces and in trenches, collection of grab samples, suction and box coring, grain size and total organic carbon analyses, optical microscopy, core logging, and daylight photography. The data presented in the paper can help in predicting facies changes across the fluvio-tidal transition of sand-dominated fluvio-tidal deposits in the rock record. The lower inner estuary is characterized by medium-fine and fine-medium sand with planar and trough cross-bedding, small-scale ripple lamination, tidal sedimentary structures (flaser and wavy bedding, herringbone cross-stratification), abundant organic debris, and mud rip-up clasts. Bioturbation of the intertidal point bars is low, but cryptobioturbation is locally observed. Upper inner estuary deposits comprise coarse-medium- and medium-coarse-grained sand, and are characterized by faint high-angle planar and trough cross-bedding. Organic debris, mud rip-up clasts, herringbone and current-ripple lamination are rarely observed. Bioturbation is absent to sparse. The fluvio-tidal transition is represented by very-coarse- to coarse-grained sand and granules. Physical sedimentary structures constitute massive, graded planar and trough cross-bedding with abundant plant detritus. Except for rare Siphonichnus- and Lockeia-like traces, bioturbation is absent. The fluvial setting is characterized by coarse-medium sand with unidirectional cross-bedding, current-ripple lamination, and rare organic-rich mud clasts. Bioturbation is absent. Inner

  4. Sedimentology and High Resolution Sequence Stratigraphy of the Middle Jurassic Dhruma Formation Carbonates Outcrops in the Central Saudi Arabia

    Yousif, Ibrahim; Abdullatif, Osman; Makkawi, Mohammed; Abdulghani, Waleed


    This study investigates the microfacies and sequence stratigraphic frame work of the Middle Jurassic Dhruma Formation in outcrops in central Saudi Arabia. The study contributes to the efforts to understand and enhance local and regional stratigraphic relationship and correlation of the Jurassic carbonate sequences and their significance to reservoir description and prediction in the subsurcae. The study describes and characterizes the sedimentology, microfacies and the stratigraphy of Dhruma Formation from outcrop sections having a total thickness of 70 m. Detailed microfacies and high-resolution stratigraphical analysis were carried out to determine microfacies, cyclicity, sequences and staking pattern. The study revealed ten lithofacies namely: oolitic grainstone,bioclastic oolitic grainstone, oolitic grapestone, bioclastic grainstone,foraminiferal packstone, echinoderm packstone, peloidal packstone to grainstone,skeletal wackestone to packstone, mudstone, and marlstone.These lithofacies were grouped into five lithofacies associations that deposited on a carbonate ramp setting. The depositional environment ranging from low energy lagoonal setting to high-energy shoals and banks to low energy outer ramp setting. Five high-resolution composite sequences have been defined and each sequence is composed at the bottom of intercalated mudstone/wackestone that passing up into grainstone lithofacies.The composite sequences range in thickness from 7 to 15 m, while the parasequences range from 0.5 to 1.5 m. The composite sequences extend laterally for a distance of more than 350 m. The overall composite section shows a shallowing upward succession of the 4th to the 5th order high-resolution sequences.The dominant lithofacies are the grainy ones, which constitute 30%, 50% and 80% of the studied sections. Furthermore, the parasequences thickness and their bio-components are increasing towards the top. The muddy lithofacies intensively affected the vertical continuity of the

  5. Space, matter and topology

    Asorey, Manuel


    An old branch of mathematics, Topology, has opened the road to the discovery of new phases of matter. A hidden topology in the energy spectrum is the key for novel conducting/insulating properties of topological matter.

  6. Theory of nuclear matter

    Avakyan, R.M.; Sarkisyan, A.V.


    The properties of degenerate stellar matter in the region of nuclear densities are considered. The threshold of the transition of the electron-nucleus phase to the state of continuous nuclear matter is found.

  7. Mind Over Matter: Cocaine

    ... Term(s): Teachers / NIDA Teaching Guide / Mind Over Matter Teaching Guide and Series / Cocaine Print Mind Over Matter: Cocaine Order Free Publication in: English Spanish Download PDF 806.08 KB Cocaine is ...

  8. Why Arrhythmia Matters

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Why Arrhythmia Matters Updated:Dec 21,2016 When the heart's ... fibrillation. This content was last reviewed September 2016. Arrhythmia • Home • About Arrhythmia • Why Arrhythmia Matters • Understand Your ...

  9. Cannibal Dark Matter

    Pappadopulo, Duccio; Trevisan, Gabriele


    A thermally decoupled hidden sector of particles, with a mass gap, generically enters a phase of cannibalism in the early Universe. The Standard Model sector becomes exponentially colder than the hidden sector. We propose the Cannibal Dark Matter framework, where dark matter resides in a cannibalizing sector with a relic density set by 2-to-2 annihilations. Observable signals of Cannibal Dark Matter include a boosted rate for indirect detection, new relativistic degrees of freedom, and warm dark matter.

  10. Dark Matter Effective Theory

    Del Nobile, Eugenio; Sannino, Francesco


    We organize the effective (self)interaction terms for complex scalar dark matter candidates which are either an isosinglet, isodoublet or an isotriplet with respect to the weak interactions. The classification has been performed ordering the operators in inverse powers of the dark matter cutoff...... scale. We assume Lorentz invariance, color and charge neutrality. We also introduce potentially interesting dark matter induced flavor-changing operators. Our general framework allows for model independent investigations of dark matter properties....

  11. Impeded Dark Matter

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei


    We consider a new class of thermal dark matter models, dubbed "Impeded Dark Matter", in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. We demonstrate that either case can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonst...

  12. Neutron Star Matter

    Wambach, Jochen


    In this presentation I discuss two aspects of the neutron-matter equation of state. One relates to the symmetry energy of nuclear matter and empirical constraints on its slope parameter at saturation density. The second deals with spatially inhomogeneous chiral phases of deconfined quark matter in the inner core of a neutron star.

  13. Determining flow directions in turbidites: An integrated sedimentological and magnetic fabric study of the Miocene Marnoso Arenacea Formation (northern Apennines, Italy)

    Felletti, Fabrizio; Dall'Olio, Eleonora; Muttoni, Giovanni


    Depositional models of turbidity flows require estimating paleocurrent directions using sedimentological indicators such as flute and ripple marks, but these are not always present in outcrop sections or drill cores. In this study, we apply the anisotropy of magnetic susceptibility (AMS) as an alternative tool to estimate paleocurrent directions in a case-study turbiditic system: the Marnoso Arenacea foredeep turbidites of Miocene age exposed in the northern Apennines of Italy. Different depositional facies have been sampled for AMS and additional rock-magnetic analyses. We observed a good agreement between paleocurrent directions from flute casts at the base of turbidite beds and mean directions of maximum magnetic susceptibility axes in organized facies such as massive and laminated sandstones, even if a relatively small but apparently consistent offset of ~ 15-20° seems to be present. Highly dispersed AMS fabrics were instead observed in disordered facies such as convoluted and undulated sandstones as well as debrites. This strong correlation between hydrodynamic regimes of depositional facies and AMS data represents a novel contribution and confirms the validity of the AMS method to estimate flow directions in the absence of sedimentological indicators. Finally, paleomagnetic analyses from the literature were used to reconstruct the paleogeography of the Marnoso Arenacea basin and make inferences about the origin and direction of transport of the sediments at the basin scale.

  14. Assessing the impact of diagenesis on δ11B, δ13C, δ18O, Sr/Ca and B/Ca values in fossil planktic foraminiferal calcite

    Edgar, Kirsty M.; Anagnostou, Eleni; Pearson, Paul N.; Foster, Gavin L.


    The geochemical composition of foraminiferal tests is a valuable archive for the reconstruction of paleo-climatic, -oceanographic and -ecological changes. However, dissolution of biogenic calcite and precipitation of inorganic calcite (overgrowth and recrystallization) at the seafloor and in the sediment column can potentially alter the original geochemical composition of the foraminiferal test, biasing any resulting paleoenvironmental reconstruction. The δ11B of planktic foraminiferal calcite is a promising ocean pH-proxy but the effect of diagenesis is still poorly known. Here we present new δ11B, δ13C, δ18O, Sr/Ca and B/Ca data from multiple species of planktic foraminifera from time-equivalent samples for two low latitude sites: clay-rich Tanzanian Drilling Project (TDP) Site 18 from the Indian Ocean containing well-preserved ('glassy') foraminifera and carbonate-rich Ocean Drilling Program (ODP) Site 865 from the central Pacific Ocean hosting recrystallized ('frosty') foraminifera. Our approach makes the assumption that environmental conditions were initially similar at both sites so most chemical differences are attributable to diagenesis. Planktic foraminiferal δ18O and δ13C records show offsets in both relative and absolute values between the two sites consistent with earlier findings that these isotopic ratios are strongly influenced by diagenetic alteration. Sr/Ca and B/Ca ratios in planktic foraminiferal calcite are also offset between the two sites but there is little change in the relative difference between surface and deep dwelling taxa. In contrast, δ11B values indicate no large differences between well-preserved and recrystallized foraminifera suggesting that despite extensive diagenetic alteration the δ11B of biogenic calcite appears robust, potentially indicative of a lack of free exchange of boron between pore fluids and the recrystallizing CaCO3. Our finding may remove one potential source of uncertainty in δ11B based p

  15. Investigations in Martian Sedimentology

    Moore, Jeffrey M.


    The purpose of this report is to investigate and discuss the Martian surface. This report was done in specific tasks. The tasks were: characterization of Martian fluids and chemical sediments; mass wasting and ground collapse in terrains of volatile-rich deposits; Mars Rover terrestrial field investigations; Mars Pathfinder operations support; and Martian subsurface water instrument.

  16. The influence of climate on early and burial diagenesis of Triassic and Jurassic sandstones from the Norwegian – Danish Basin

    Weibel, Rikke; Olivarius, Mette; Kjøller, Claus


    to the Gassum Formation, which was characterized by quartz and more stable heavy minerals. The arid to semi-arid climate led to early oxidising conditions under which abundant iron-oxide/hydroxide coatings formed, while the evaporative processes occasionally resulted in caliche and gypsum precipitation. Under...... and geochemical study complemented by porosity and permeability measurements of cores widely distributed in the basin (1700 – 5900 m burial depth). The Skagerrak Formation had an immature composition with more abundant feldspar, rock fragments and a larger variability in the heavy mineral assemblage when compared...... the humid climate, kaolinite precipitated due to leaching of feldspar and mica, and the abundant organic matter caused reducing conditions, which led to other Fe-rich phases, i.e. pyrite, Fe-chlorite and siderite. The inherited early diagenetic pore fluids and mineral assemblage also affect the mineral...

  17. Impeded Dark Matter

    Kopp, Joachim; Slatyer, Tracy R; Wang, Xiao-Ping; Xue, Wei


    We consider a new class of thermal dark matter models, dubbed "Impeded Dark Matter", in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. We demonstrate that either case can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppress...

  18. How dark matter came to matter

    de Swart, J. G.; Bertone, G.; van Dongen, J.


    The history of the dark matter problem can be traced back to at least the 1930s, but it was not until the early 1970s that the issue of 'missing matter' was widely recognized as problematic. In the latter period, previously separate issues involving missing mass were brought together in a single anomaly. We argue that reference to a straightforward accumulation of evidence alone is inadequate to comprehend this episode. Rather, the rise of cosmological research, the accompanying renewed interest in the theory of relativity and changes in the manpower division of astronomy in the 1960s are key to understanding how dark matter came to matter. At the same time, this story may also enlighten us on the methodological dimensions of past practices of physics and cosmology.

  19. How Dark Matter Came to Matter

    de Swart, Jaco; Bertone, Gianfranco; Dongen, Jeroen


    The history of the dark matter problem can be traced back to at least the 1930s, but it was not until the early 1970s that the issue of 'missing matter' was widely recognized as problematic. In the latter period, previously separate issues involving missing mass were brought together in a single anomaly. We argue that reference to a straightforward 'accumulation of evidence' alone is inadequate to comprehend this episode. Rather, the rise of cosmological research, the accompanying renewed int...

  20. Pelagic-benthic coupling and diagenesis of nucleic acids in a deep-sea continental margin and an open-slope system of the Eastern Mediterranean.

    Dell'anno, Antonio; Corinaldesi, Cinzia; Stavrakakis, Spyros; Lykousis, Vasilis; Danovaro, Roberto


    Downward fluxes of nucleic acids adsorbed onto settling particles play a key role in the supply of organic phosphorus and genetic material to the ocean interior. However, information on pelagic-benthic coupling, diagenesis, and processes controlling nucleic acid preservation in deep-sea sediments is practically nonexistent. In this study, we compared nucleic acid fluxes, sedimentary DNA and RNA concentrations, and the enzymatically hydrolyzable fraction of DNA in a bathyal continental margin (North Aegean Sea) and an open-sea system (South Aegean Sea) of the Eastern Mediterranean. The two systems displayed contrasting patterns of nucleic acid fluxes, which increased significantly with depth in the North Aegean Sea and decreased with depth in the South Aegean Sea. These results suggest that in continental margin and open-ocean systems different processes control the nucleic acid supply to the sea floor. Differences in nucleic acid fluxes were reflected by nucleic acid concentrations in the sediments, which reached extremely high values in the North Aegean Sea. In this system, a large fraction of DNA may be buried, as suggested by the large fraction of DNA resistant to nuclease degradation and by estimates of burial efficiency (ca. eight times higher in the North than in the South Aegean Sea). Overall, the results reported here suggest that the preservation of DNA in deeper sediment layers may be favored in benthic systems characterized by high sedimentation rates.

  1. Carbonate cementation as related to the diagenesis of clay in a mixed siliciclastic-carbonate system: Examples from the Centerfield biostrome, east central Pennsylvania

    Burns, C.D. (Univ. of North Carolina, Chapel Hill, NC (United States))


    The Middle Devonian Mahantango Formation consists of siliciclastic and mixed carbonate-siliciclastic sediment packages that pulse in and out of the stratigraphy. The formation crops out in several places throughout the folded rocks of eastern Pennsylvania and Maryland. The Centerfield Member is one of the mixed siliciclastic-carbonate packages in the Mahantango Fm. This member crops out in east central Pennsylvania. The Centerfield Mbr. has been interpreted as a series of biostromes and contain abundant rugosan corals, crinoids, bryozoans, and brachiopods. The biostromes have undergone a complex diagenetic history. Illite, smectite, chlorite and muscovite have been found with the use of powder x-ray diffraction and petrographic analysis. The smectite and some of the illite are depositional clays, while, the remaining illite, chlorite and muscovite represent recrystallization of the depositional clays. There are six phases of cement in the biostrome. The paragenetic sequence of the cements is as follows: non-ferroan low magnesian calcite (LMC), intermediate ferroan LMC, ferroan LMC, non-ferroan dolomite, ferroan baroque dolomite, and quartz cement in the form of chert and blocky cement. Staining shows that the iron content of the cement changes within individual crystals and between cement phases. Preliminary data suggest that the cements may be directly related to the steady release of ions during the diagenesis of the surrounding clays in the shale.

  2. Diagenesis and Restructuring Mechanism of Oil and Gas Reservoir in the Marine Carbonate Formation, Northeastern Sichuan: A Case Study of the Puguang Gas Reservoir

    DU Chunguo; WANG Jianjun; ZOU Huayao; ZHU Yangming; WANG Cunwu


    Based on the technology of balanced cross-section and physical simulation experiments associated with natural gas geochemical characteristic analyses, core and thin section observations, it has been proven that the Puguang gas reservoir has experienced two periods of diagenesis and restructuring since the Late lndo-Chinese epoch. One is the fluid transfer controlled by the tectonic movement and the other is geochemical reconstruction controlled by thermochemical sulfate reduction (TSR). The middle Yanshan epoch was the main period that the Puguang gas reservoir experienced the geochemical reaction of TSR. TSR can recreate the fluid in the gas reservoir, which makes the gas drying index higher and carbon isotope heavier because C_(2+) (ethane and heavy hydrocarbon) and ~(12)C (carbon 12 isotope) is first consumed relative to CH_4 and ~(13)C (carbon 13 isotope). However, the reciprocity between fluid regarding TSR (hydrocarbon, sulfureted hydrogen (H_2S), and water) and reservoir rock results in reservoir rock erosion and anhydrite alteration, which increases porosity in reservoir, thereby improving the petrophysical properties. Superimposed by later tectonic movement, the fluid in Puguang reservoir has twice experienced adjustment, one in the late Yanshan epoch to the early Himalayan epoch and the other time in late Himalayan epoch, after which Puguang gas reservoir is finally developed.

  3. Reconstruction of the sedimentological environment and paleo-tsunami events offshore Jisr Az-Zarka (central Israel)

    Tyuleneva, Natalia; Braun, Yael; Suchkov, Igor; Ben-Avraham, Zvi; Goodman-Tchernov, Beverly


    Previous research shows that cores retrieved offshore central Israel (Caesarea) have anomalous sedimentary sequences that correspond to at least three tsunami events. Identification of the tsunami horizons was carried out by quantifying the presence of a wide range of characteristics described in modern and paleotsunami analogs. In this study, a sediment core (219cm) was obtained from 15.3 m water depth, some 1.5 km to the south-west of the Crocodile River mouth, offshore the village of Jisr Az-Zarka, and ~4 km north of Caesarea. The core was sampled at 1 cm intervals for grain size and micropaleontological analyses. XRD and XRF analyses were also performed at coarser resolution. The aim of the study was to correlate anomalous layers in the core with previously identified tsunami layers off Caesarea and to test whether their expression differs, given the impact of the river runoff and land material input. An additional aim was to study the inter-event sediments to determine broader environmental changes. This is uniquely possible here because the maximum age of the deposits (change influence; and this portion of the coastline is considered tectonically quiet for at least 2000 years; thereby negating two possible effects on the sedimentological signatures. In this new core two tsunami horizons corresponding with known Caesarea events (~1200 yBP, perhaps 749 AD earthquake; and ~3500 yBP 'Santorini eruption') were recognized, and, one previously unidentified event, dated by 14C to 5.6-6 ka, was discerned as well. The Nile River has been the dominant and most stable source of terrigenous components in the study area, such as siliciclastic quartz for the sand fraction and smectite - for the clays. Thus, the prevailing marine settings are dominated by these two mineralogical components. XRD analysis of nine intervals in the core determined the following clay minerals: smectite, hydromica (illite), chlorite and kaolinite. Normal marine settings are characterized by the

  4. Recent sedimentological studies of the Murray and Stimson formations and their implications for Gale crater evolution, Mars

    Gupta, Sanjeev; Fedo, Chris; Grotzinger, John; Edgett, Ken; Vasavada, Ashwin


    The Mars Science Laboratory (MSL) Curiosity rover has been exploring sedimentary rocks on the lower north slope of Aeolis Mons since August 2014. Previous work has demonstrated a succession of sedimentary rock types deposited dominantly in river-delta settings (Bradbury group), and interfingering/overlying contemporaneous/younger lake settings (Murray formation, Mt. Sharp group). The Murray formation is unconformably overlain by the Stimson formation, an ancient aeolian sand lithology. Here, we describe the MSL team's most recent sedimentological findings regarding the Murray and Stimson formations. The Murray formation is of the order of 200 meters thick and formed dominantly of mudstones. The mudstone facies, originally identified at the Pahrump Hills field site, show abundant fine-scale planar laminations throughout the Murray formation succession and is interpreted to record deposition in an ancient lake system in Gale crater. Since leaving the Naukluft Plateau (Stimson formation rocks) and driving south-southeastwards and progressive stratigraphically upwards through the Murray succession, we have recognised a variety of additional facies have been recognized that indicate variability in the overall palaeoenvironmental setting. These facies include (1) cross-bedded siltstones to very fine-grained sandstones with metre-scale troughs that might represent aeolian sedimentation; (2) a heterolithic mudstone-sandstone facies with laminated fine-grained strata, cm-scale ripple cross-laminations in siltstone or very fine sandstone, and dm-scale cross-stratified siltstone and very fine grained sandstone. The palaeoenvironmental setting for the second facies remains under discussion. Our results show that Gale crater hosted lakes systems for millions to tens of millions of years, perhaps punctuated by drier intervals. Murray strata are unconformably overlain by the Stimson formation. Stimson outcrops are typically characterized by cross-bedded sandstones with cross

  5. Basin Evolution and Exhumation of the Xigaze Forearc, Southern Tibet: Insight from Sedimentology, Stratigraphy, and Geo-Thermochronology

    Orme, D. A.; Carrapa, B.; Abbey, A. L.; Kapp, P. A.; Ding, L.


    Forearc basins are important data archives for understanding continental dynamics because they preserve the tectono-erosional record of continental margins before collision. This study focuses on the Cretaceous-Eocene Xigaze forearc basin in southern Tibet, which is exposed along ~600 km of the Indus-Yarlung Suture Zone between the Indian craton to the south and the Asian Lhasa terrane to the north. From late Cretaceous to early Cenozoic time, subduction of Neo-Tethyan oceanic crust beneath the southern margin of Asia accommodated the northward motion of the Indian craton and formed the Xigaze forearc basin. Following collision with India in the early Cenozoic, the basin transitioned from predominantly marine to non-marine sedimentation and was subsequently uplifted to a mean elevation of 5000 m. How this transition occurred remains unresolved. This study's overall objective is to decipher forearc-basin and Indo-Asia continental-margin development from field sedimentology and stratigraphy, and detrital geo-thermochronology. We present new stratigraphic sections, totaling 8 km thick, from a previously unexplored ~60 km segment of the Xigaze forearc, ~50 km north-northwest of Saga. These sections are quite different from those known farther east. Sedimentary facies of mid-Cretaceous to early Eocene deposits indicate a shoaling-upward trend consistent with other ancient forearc basins (e.g., Great Valley forearc, California). Middle to late Cretaceous deposits indicate a variety of facies and depositional environments along strike in the study area. Facies include distal marine turbidites, shelf limestones, estuarine siliciclastics, and brown paleosols. In contrast, Eocene depositional environments are transitional from nearshore marine to pericontinental. Facies consist of dirty limestones, packstones, and wackestones, interbedded with terrigenous conglomerates and red-green paleosols. Eocene fauna include abundant foraminifera such as Nummulites-Discocyclina and

  6. Disentangling the record of diagenesis, local redox conditions, and global seawater chemistry during the latest Ordovician glaciation

    Ahm, Anne-Sofie C.; Bjerrum, Christian J.; Hammarlund, Emma U.


    The Late Ordovician stratigraphic record integrates glacio-eustatic processes, water-column redox conditions and carbon cycle dynamics. This complex stratigraphic record, however, is dominated by deposits from epeiric seas that are susceptible to local physical and chemical processes decoupled from the open ocean. This study contributes a unique deep water basinal perspective to the Late Ordovician (Hirnantian) glacial record and the perturbations in seawater chemistry that may have contributed to the Hirnantian mass extinction event. We analyze recently drilled cores and outcrop samples from the upper Vinini Formation in central Nevada and report combined trace- and major element geochemistry, Fe speciation (FePy /FeHR and FeHR /FeT), and stable isotope chemostratigraphy (δ13COrg and δ34SPy). Measurements of paired samples from outcrop and core reveal that reactive Fe is preserved mainly as pyrite in core samples, while outcrop samples have been significantly altered as pyrite has been oxidized and remobilized by modern weathering processes. Fe speciation in the more pristine core samples indicates persistent deep water anoxia, at least locally through the Late Ordovician, in contrast to the prevailing interpretation of increased Hirnantian water column oxygenation in shallower environments. Deep water redox conditions were likely decoupled from shallower environments by a basinal shift in organic matter export driven by decreasing rates of organic matter degradation and decreasing shelf areas. The variable magnitude in the record of the Hirnantian carbon isotope excursion may be explained by this increased storage of isotopically light carbon in the deep ocean which, in combination with increased glacio-eustatic restriction, would strengthen lateral- and vertical gradients in seawater chemistry. We adopt multivariate statistical methods to deconstruct the spatial and temporal re-organization of seawater chemistry during the Hirnantian glaciation and attempt to

  7. Teachers Matter. Yes. Schools Matter. Yes. Districts Matter--Really?

    Chenoweth, Karin


    School districts shape the conditions in which schools operate and as such can support or undermine school success and thus student success. All of which is to say that school districts matter. This article looks at the success of two districts whose low-income and minority students beat the odds in academic achievement. Lessons from these…

  8. Ocean metabolism and dissolved organic matter: How do small dissolved molecules persist in the ocean?

    Benner, Ronald


    The ocean reservoir of dissolved organic matter (DOM) is among the largest global reservoirs (~700 Pg C) of reactive organic carbon. Marine primary production (~50 Pg C/yr) by photosynthetic microalgae and cyanobacteria is the major source of organic matter to the ocean and the principal substrate supporting marine food webs. The direct release of DOM from phytoplankton and other organisms as well as a variety of other processes, such as predation and viral lysis, contribute to the ocean DOM reservoir. Continental runoff and atmospheric deposition are relatively minor sources of DOM to the ocean, but some components of this material appear to be resistant to decomposition and to have a long residence time in the ocean. Concentrations of DOM are highest in surface waters and decrease with depth, a pattern that reflects the sources and diagenesis of DOM in the upper ocean. Most (70-80%) marine DOM exists as small molecules of low molecular weight (1 kDalton) DOM is relatively enriched in major biochemicals, such as combined neutral sugars and amino acids, and is more bioavailable than low-molecular-weight DOM. The observed relationships among the size, composition, and reactivity of DOM have led to the size-reactivity continuum model, which postulates that diagenetic processes lead to the production of smaller molecules that are structurally altered and resistant to microbial degradation. The radiocarbon content of these small dissolved molecules also indicates these are the most highly aged components of DOM. Chemical signatures of bacteria are abundant in DOM and increase during diagenesis, indicating bacteria are an important source of slowly cycling biochemicals. Recent analyses of DOM isolates by ultrahigh-resolution mass spectrometry have revealed an incredibly diverse mixture of molecules. Carboxyl-rich alicyclic molecules are abundant in DOM, and they appear to be derived from diagenetically-altered terpenoids, such as sterols and hopanoids. Thermally

  9. Neutrinos and dark matter

    Ibarra, Alejandro [Physik-Department T30d, Technische Universität München, James-Franck-Straße, 85748 Garching (Germany)


    Neutrinos could be key particles to unravel the nature of the dark matter of the Universe. On the one hand, sterile neutrinos in minimal extensions of the Standard Model are excellent dark matter candidates, producing potentially observable signals in the form of a line in the X-ray sky. On the other hand, the annihilation or the decay of dark matter particles produces, in many plausible dark matter scenarios, a neutrino flux that could be detected at neutrino telescopes, thus providing non-gravitational evidence for dark matter. More conservatively, the non-observation of a significant excess in the neutrino fluxes with respect to the expected astrophysical backgrounds can be used to constrain dark matter properties, such as the self-annihilation cross section, the scattering cross section with nucleons and the lifetime.

  10. Codecaying Dark Matter.

    Dror, Jeff Asaf; Kuflik, Eric; Ng, Wee Hao


    We propose a new mechanism for thermal dark matter freeze-out, called codecaying dark matter. Multicomponent dark sectors with degenerate particles and out-of-equilibrium decays can codecay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross section, which is predicted to be boosted, and the decay rate of the dark sector particles. The mechanism is viable in a broad range of dark matter parameter space, with a robust prediction of an enhanced indirect detection signal. Finally, we present a simple model that realizes codecaying dark matter.

  11. The mystery of matter

    Trusted, Jennifer


    As Russell said The word matter is, in philosophy, the name of a problem and our scientific investigations and philosophical inquiries show that it becomes more and more complex and interesting as we study it. This book seeks to show how ideas of matter have developed from Democritus to Heisenberg. The problem of matter may well be insoluble but at least we can begin to appreciate the mystery of what is so often taken to be the mundane 'stuff' of common sense.

  12. Antibaryonic dark matter

    Gorbunov, D


    Assuming existence of (very) heavy fourth generation of quarks and antiquarks we argue that antibaryon composed of the three heavy antiquarks can be light, stable and invisible, hence a good candidate for the Dark matter particle. Such opportunity allows to keep the baryon number conservation for the generation of the visible baryon asymmetry. The dark matter particles traveling through the ordinary matter will annihilate with nucleons inducing proton(neutron)-decay-like events with ~5GeV energy release in outcoming particles.

  13. Dark Matter Constituents

    Bergström, L


    As cosmology has entered a phase of precision experiments, the content of the universe has been established to contain interesting and not yet fully understood components, namely dark energy and dark matter. While the cause and exact nature of the dark energy remains mysterious, there is greater hope to connect the dark matter to current models of particle physics. Supersymmetric models provide several excellent candidates for dark matter, with the lightest neutralino the prime example. This and other dark matter candidates are discussed, and prospects for their detection summarized. Some methods of detection are explained, and indications of signals in present data are critically examined.

  14. Soft matter physics

    Doi, Masao


    Soft matter (polymers, colloids, surfactants and liquid crystals) are an important class of materials in modern technology. They also form the basis of many future technologies, for example in medical and environmental applications. Soft matter shows complex behaviour between fluids and solids, and used to be a synonym of complex materials. Due to the developments of the past two decades, soft condensed matter can now be discussed on the same sound physical basis as solid condensedmatter. The purpose of this book is to provide an overview of soft matter for undergraduate and graduate students

  15. Searches for dark matter

    Feinstein, Fabrice


    The fact that the mass of the visible stars could not account for the gravitational cohesion of the galaxies was the first sign of non-visible (i.e. dark) matter in the Universe. Since then, many observational evidences tell us that most of the matter is indeed dark. The nature of this dark matter is still unknown. There are good reasons to think that most of it is not composed of normal matter. These lectures will review the experimental methods, which have been developed to unravel this mystery and will compare their results with theoretical predictions.

  16. Current hot topics and advances of sedimentology:A summary from 19th International Sedimentological Congress%沉积学研究热点与进展:第19届国际沉积学大会综述

    鲜本忠; 朱筱敏; 岳大力; 郑秀娟


    基于第19届国际沉积学大会资料,分析了当前国际沉积学研究热点和研究进展,指出除了资源沉积学研究持续走热外,全球气候变化沉积记录、深水沉积与事件沉积和碳酸盐与微生物沉积成为当前沉积学3大热门研究领域。全球气候沉积记录领域的进展表现在气候的沉积记录载体研究,特殊地质时期或地域气候效应及早期气候宏观变化规律研究;深水沉积与事件沉积领域的进展包括水力跳跃、深水实地监测等重力流沉积过程研究,地震、海啸、洪水、火山等事件沉积学及重力流沉积预测及油气勘探;碳酸盐与微生物沉积领域的进展包含冷水碳酸盐沉积和微生物对碳酸盐沉积的控制。对比表明,中国沉积学研究在环境上关注河湖等陆相多,风成、冰川和海岸等研究较薄弱;性质上以资源沉积学等应用研究为主导,沉积动力过程等基础研究薄弱;热点领域上对深水沉积和非常规油气领域关注多,但多局限于沉积现象描述与油气勘探开发实践。笔者指出,注重碎屑物沉积动力过程和源—渠—汇系统分析,及时引进深水和冷水碳酸盐沉积理论、发展生物地质学,充分利用大量科探和油田钻孔资料开展全球气候研究,是近期中国沉积学突破的可能方向。%The current research hotspots and advances of international sedimentology has been ana-lyzed based on the data of 19th International Sedimentological Congress,which indicates that global cli-matic sedimentary record,deepwater sedimentology and event deposition,and carbonate and microbial sedimentology are becoming the three current hot issues in sedimentology besides the continual hot topic:resources sedimentology.Main progresses in global climate sedimentary record came from sedimentary re-corders exploration for detailed climate change,climatic environmental and ecological effects and the cli

  17. Early diagenesis and clay mineral adsorption as driving factors of metal pollution in sediments: the case of Aveiro Lagoon (Portugal).

    Martins, Maria Virgínia Alves; Mane, Miguel Ângelo; Frontalini, Fabrizio; Santos, José Francisco; da Silva, Frederico Sobrinho; Terroso, Denise; Miranda, Paulo; Figueira, Rubens; Laut, Lazaro Luiz Mattos; Bernardes, Cristina; Filho, João Graciano Mendonça; Coccioni, Rodolfo; Dias, João M Alveirinho; Rocha, Fernando


    This work aims to define the factors driving the accumulation of metals in the sediment of the lagoon of Aveiro (Portugal). The role of initial diagenetic processes in controlling trace metal retention in surface sediment is traced by mineralogy, magnetic susceptibility and geochemical analyses. Although several studies have focused on the metal distribution in this polihaline and anthropized coastal lagoon, most of them have been solely focused on the total metal concentrations. This study instead represents the first attempt to evaluate in a vast area of the Aveiro Lagoon the role of biogeochemical processes in metal availability and distribution in three extracted phases: exchangeable cations adsorbed by clay and elements co-precipitated with carbonates (S1), organic matter (S2) and amorphous Mn hydroxides (S3). According to the sediment guideline values, the sediment is polluted by, for instance, As and Hg in the inner area of the Murtosa Channel, Pb in the Espinheiro Channel, Aveiro City canals and Aveiro Harbour, and Zn in the northern area of the Ovar Channel. These sites are located near the source areas of pollutants and have the highest total available concentrations in each extracted phase. The total available concentrations of all toxic metals are however associated, firstly, with the production of amorphous Mn hydroxides in most of the areas and, secondly, with adsorption by organic compounds. The interplay of the different processes implies that not all of the sites near pollution sources have polluted surface sediment. The accumulation of metals depends on not only the pollution source but also the changing in the redox state of the sediments that may cause alterations in the sediment retention or releasing of redox-sensitive metals. Results of this work suggest that the biogeochemical processes may play a significant role in the increase of the pollutants in the sediment of the Aveiro Lagoon.

  18. Sedimentological and paleontological features of sea floor sediments of Penta Palummo and Miseno volcanic highs, Gulf od Naples (South-eastern Tyrrhenian Sea)

    Ferraro, L.; Molisso, F. [Consiglio Nazionale delle Ricerche, Naples (Italy). Ist. di Ricerca Geomare Sud


    A sedimentological and paleontological study has been carried out on surficial sediments of Penta Palummo and Miseno volcanic banks, in the Gulf of Naples (South-eastern Tyrrhenian Sea, Italy). The deposits consist of bioclastic sand (coralline algae, bryozoans, gastropods, bivalvs and echinoderms). The benthic foraminiferal assemblage is mainly characterized by epiphytic species. Bioclastics sand is autochtonous and derived from breakdown of algal buildups. [Italian] Uno studio sedimentologico e paleontologico e' stato condotto sui sedimenti superficiali dei banchi vulcanici di Penta Palummo e di Miseno (Golfo di Napoli, Mar Tirreno sudorientale). I depositi sono costituiti da sabbie bioclastiche (alghe coralline, briozoi, gasteropodi, bivalvi ed echonodermi). L'associazione a foraminiferi bentonici e' caratterizzata principalmente da specie epifite. Le sabbie bioclastiche sono autoctone e derivano dal disfacimento di biocostruzioni algali.

  19. A sedimentological approach for an optimal resolution of drilling mud losses; Approche sedimentologique pour une resolution optimale des problemes de pertes de boues de forage

    Kherfellah, N.; Ait Salem, H. [Sonatrach, Centre de Recherche et Developpement, Boumerdes (Algeria); Bekkour, K. [Institut de Mecanique des Fluides et des Solides, UMR ULP-CNRS, 67 - Strasbourg (France); Benhadid, S. [Universite des Sciences et de la Technologie Houari Boumediene, Institut de Physique, Lab. de Rheologie, El Alia (Algeria)


    In spite of the geological knowledge accumulated on more than 800 uninterruptedly cored wells during the forty last years, the drilling of the 81/2'' diameter phase of Hassi-Messaoud oil field (Algeria) remains delicate because of excavation and drilling mud losses problems. The main objective of this work was to study the problem of drilling mud losses by the use of a sedimentological approach and to localize the producing levels of the subjacent Cambrian. For that purpose, the fast and slow drilling advance zones in the Triassic sedimentary sequences were localized in order to establish distribution maps. Thus, it was highlighted: - that the fast advance zones correspond to the sectors without mud losses (argillaceous facies of the flood plain), whereas the zones with slow advance correspond to the significant mud losses sectors (sandy facies of the fluviatile bars); - that under the fast advance zones of the Triassic series, potential hydrocarbon reservoirs are located. (authors)

  20. Linking Organic Matter Deposition And Iron Mineral Transformations to Groundwater Arsenic Levels in the Mekong Delta, Cambodia

    Quicksall, A.N.; Bostick, B.C.; Sampson, M.L.


    Enriched As in drinking water wells in south and Southeast Asia has increased the risk of cancer for nearly 100 million people. This enrichment is generally attributed to the reductive dissolution of Fe oxides; however, the complex expression of As enrichment in these areas is not yet well understood. Here, the coupled sedimentological and geochemical factors that contribute to the extent and spatial distribution of groundwater As concentrations in the Mekong River delta, Cambodia in an avulsed scroll bar sequence are examined. X-Ray absorption spectroscopy (XAS) was used to determine Fe and As speciation in redox preserved sediment collected from drilled cores. Dissolved As, Fe and S solution concentrations in existing and newly drilled wells (cores) differed considerably depending on their source sedimentology. The rapid burial of organic matter in the scroll bar sequence facilitated the development of extensive Fe-reducing conditions, and As release into the aquifer. In older features organic C levels are high enough to sustain extensive Fe reduction and provide ample SO{sub 4} which is reduced to sulfide. This S reduction impacts As levels; As is sequestered in sulfide minerals outside of the scrollbar sequence, decreasing pore water concentrations. In contrast, As is depleted in sediments from the scroll sequence, and associated with elevated pore water aqueous concentrations. The concentration and form of organic C in the scrollbar sequence is related to depositional environment, and can facilitate Fe and S mineral transformations, distinct sedimentary environments explain a portion of the inherent heterogeneity of aquifer As concentrations.

  1. Different Kinds of Matter(s)

    Rosfort, René


    This article questions the methodological conflation at work in Karen Barad's agential realism. Barad's immense appeal is first explained against the tense background of the nature/culture antagonism in the twentieth century. Then, by using some of the penetrating observations of a seventeen......-century philosopher, Princess Elisabeth of Bohemia, Barad's “ethico-onto-epistem-ology” is examined and subsequently criticized for disregarding the persistence of subjectivity, dissolving the ambivalence of the bodily matter(s), and neglecting the need for concrete individuality in ethics....

  2. On the Matter of N=2 Matter

    Doran, C F; Gates, S J Jr; Hübsch, T; Iga, K M; Landweber, G D


    We introduce a variety of four-dimensional N = 2 matter multiplets which have not previously appeared explicitly in the literature. Using these, we develop a class of supersymmetric actions supplying a context for a systematic exploration of N = 2 matter theories, some of which include Hypermultiplet sectors in novel ways. We construct an N = 2 supersymmetric field theory in which the propagating fields are realized off-shell exclusively as Lorentz scalars and Weyl spinors and which involves a sector with precisely the R-charge assignments characteristic of Hypermultiplets.

  3. Dark matter and cosmology

    Schramm, D.N.


    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold`` and ``hot`` non-baryonic candidates is shown to depend on the assumed ``seeds`` that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  4. Dark matter and cosmology

    Schramm, D.N.


    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between cold'' and hot'' non-baryonic candidates is shown to depend on the assumed seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  5. Asymptotically Safe Dark Matter

    Sannino, Francesco; Shoemaker, Ian M.


    We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting...... searches are the primary ways to constrain or discover asymptotically safe dark matter....

  6. Asymptotically Safe Dark Matter

    Sannino, Francesco; Shoemaker, Ian M.


    We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting...... searches are the primary ways to constrain or discover asymptotically safe dark matter....

  7. Dipolar Dark Matter

    Blanchet, Luc


    Massive gravity theories have been developed as viable IR modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because the two types of dark matter interact through the vector field, a ghostly degree of fre...

  8. Energy and matter

    Gobato, Ricardo; Fedrigo, Desire Francine Gobato


    Our work is an approach between matter and energy. Using the famous equation E = mc^2, Einstein and the Law of Universal Gravitation of Newton, we estimate that a small amount matter converted into energy is needed to lift, using the gravitational potential energy equation on the surface, a mountain of solid iron or even Mount Everest.

  9. Matter in transition

    Anderson, Lara B.; Gray, James; Raghuram, Nikhil; Taylor, Washington


    We explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, where a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU( N) require Weierstrass models that cannot be realized from the standard SU( N) Tate form. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements another recent analogous construction.

  10. Management does matter

    Kroustrup, Jonas

    studies approach the paper acknowledges that management and project management technologies does matter, but comes in many shapes, and is performed differently in various socio-technical settings. The field of STS offers a new ground for a participatory and practice oriented approach to the development...... of a new direction in project management research that puts management matter into focus....

  11. Quantifying the Texture, Composition, and Coupled Chemical-Mechanical Diagenesis of Deformation Bands within Sandstone Reservoir Outcrop Analogs of Assorted Detrital Compositions, Southwestern USA

    Elliott, S. J.; Eichhubl, P.


    formations, while the amount of chemical versus mechanical diagenesis seems to be dependent on the detrital host rock.

  12. Dark Matter Detection in Space

    Feng, Jonathan L.


    I review prospects for detecting dark matter in space-based experiments, with an emphasis on recent developments. I propose the ``Martha Stewart criterion'' for identifying dark matter candidates that are particularly worth investigation and focus on three that satisfy it: neutralino dark matter, Kaluza-Klein dark matter, and superWIMP gravitino dark matter.

  13. The Top 10 Matters That Matter


    To review what matters most to the people of China,the country’s official Xinhua News Agency created a list of the 10 greatest changes in 2007.Here are the issues that reflect the pulse of the past year

  14. Dark matter searches

    Baudis, Laura


    One of the major challenges of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the scales of galaxies up to the largest cosmological scales. The dark matter could be made of new, yet undiscovered elementary particles, with allowed masses and interaction strengths with normal matter spanning an enormous range. Axions, produced non-thermally in the early universe, and weakly interacting massive particles (WIMPs), which froze out of thermal equilibrium with a relic density matching the observations, represent two well-motivated, generic classes of dark matter candidates. Dark matter axions could be detected by exploiting their predicted coupling to two photons, where the highest sensitivity is reached by experiments using a microwave cavity permeated by a strong magnetic field. WIMPs could be directly observed via scatters off atomic nuclei in underground, ultr...

  15. Incompressibility of strange matter

    Sinha, M N; Dey, J; Dey, M; Ray, S; Bhowmick, S; Sinha, Monika; Bagchi, Manjari; Dey, Jishnu; Dey, Mira; Ray, Subharthi; Bhowmick, Siddhartha


    Strange stars calculated from a realistic equation of state (EOS) show compact objects in the mass radius curve, when they are solved for gravitational fields via TOV equation. Many of the observed stars seem to fit in with this kind of compactness irrespective of whether they are X-ray pulsars, bursters or soft $\\gamma$ repeaters or radio pulsars. Calculated incompressibility of this strange matter shows continuity with that of nuclear matter. This is important in the cosmic separation of phase scenario. We compare our calculations of incompressibility with that of a nuclear matter EOS. This EOS has a continuous transition to ud-matter at about five times normal density. From a look at the consequent velocity of sound it is found that the transition to ud-matter seems necessary.

  16. Dark matter universe.

    Bahcall, Neta A


    Most of the mass in the universe is in the form of dark matter--a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations--from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is "cold" (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology--a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)--fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

  17. Sedimentological and biostratigraphical analyses of short sediment cores from Hagelseewli (2339 m a.s.l. in the Swiss Alps

    Jacqueline F.N. VAN LEEUWEN


    Full Text Available Several short sediment cores of between 35 and 40 cm from Hagelseewli, a small, remote lake in the Swiss Alps at an elevation of 2339 m a.s.l. were correlated according to their organic matter content. The sediments are characterized by organic silts and show in their uppermost part a surprisingly high amount of organic matter (30-35%. Synchronous changes, occurring in pollen from snow-bed vegetation, the alga Pediastrum, chironomids, and grain-size composition, point to a climatic change interpreted as cooler or shorter summers that led to prolonged ice-cover on the lake. According to palynological results the sediments date back to at least the early 15th century A.D., with the cooling phase encompassing the period between late 16th and the mid-19th century thus coinciding with the Little Ice Age. Low concentrations of both chironomid head capsules and cladoceran remains in combination with results from fossil pigment analyses point to longer periods of bottom-water anoxia as a result of long-lasting ice-cover that prevented mixing of the water column. According to our results aquatic biota in Hagelseewli are mainly indirectly influenced by climate change. The duration of ice-cover on the lake controls the mixing of the water column as well as light-availability for phytoplankton blooms.

  18. The Diagenesis of Volcanic Rocks and Its Effects on the Reservior Quality in Xujiaweizi Fault Depression, Soliao Basin%徐家围子断陷火山岩成岩作用与储层质量

    胡文婷; 柳成志; 赵辉; 栾慷; 周振东; 姚洪鹏


    The Xjiaweizi fault depression is the largest volcanic reserviors ever discovered in China which is located in the northern Songliao Basin.Study of the petrological characteristics, pore types and the diagenesis of volcanic rocks, shows that volcanic rocks types can be divided into two kinds,including lavas and pyroclastic rocks, the major volcanic reservior rocks are rhyolite and ignimbrite.The reservior spaces include primary pore, primary facture,secondary pore and secondary fracture.While the favorable volcanic rock reserviors in this area are mainly composed of initial bubbles, micropores resulted from devitrification and secondary dissolution pores.The diagenesis of volcanic rocks can be devided into three stages which include syndiagenetic phase, hypergenesis phase and burialdiagenesis phase.There are 12 volcanic diagenesis types, and the reservior guality are greatly effected by the diagenesis events including packing action,devitrify and dissolution.%徐家围子断陷位于松辽盆地北部古中央隆起带东侧,断陷期火山活动强烈,营城组火山岩是本区深层天然气重要的储集空间.对徐家围子断陷营城组火山岩的岩石学特征、储集空间类型以及火山岩的成岩作用研究表明,本区火山岩岩石类型有熔岩和火山碎屑岩两大类,以流纹岩、熔结凝灰岩为主.孔隙类型有4种,不同的岩石类型具有不同的孔隙类型组合,最主要的孔隙类型为原生气孔、脱玻化孔和次生溶孔.火山岩的成岩演化可以分为三个阶段,目前本区火山岩主要出于埋藏成岩阶段II期.本区火山岩一共有12种成岩作用类型,不同成岩阶段的成岩作用类型不相同,对储层质量影响最重要的成岩作用是脱玻化作用、充填作用和溶解作用.

  19. A comprehensive survey of lignin geochemistry in the sedimentary organic matter along the Kapuas River (West Kalimantan, Indonesia)

    Loh, Pei Sun; Chen, Chen-Tung Arthur; Anshari, Gusti Z.; Wang, Jough-Tai; Lou, Jiann-Yuh; Wang, Shu-Lun


    In this first study of lignin geochemistry in the world's longest river on an island, surface sediments were collected along the Kapuas River, three lakes in the upper river, a tributary in the lower river and a separate river during June-July 2007 and December 2007-January 2008. The samples were analyzed for lignin-derived phenols and bulk elemental and stable carbon isotope compositions. Λ values (the sum of eight lignin phenols, expressed as mg/100 mg organic carbon (OC)) ranged from 0.13 to 3.70. Ratios of syringyl/vanillyl (S/V) and cinnamyl/vanillyl (C/V) ranged from 0.34 to 1.18 and 0.28 to 1.40, respectively, indicating the presence of non-woody angiosperm tissues. The high vanillic acid to vanillin (Ad/Al)v (0.71-2.01) and syringic acid to syringaldehyde (Ad/Al)s (0.72-2.12) ratios indicate highly degraded lignin materials. In the upper Kapuas River, highly degraded soil materials discharged from lands that were barren as a result of deforestation activities were detected in the locations directly in those vicinities. The middle Kapuas River showed rapid organic matter degradation, probably due to the presence of fresh terrestrial and phytoplankton organic matter fueling the biogeochemical cycling. The Kapuas Kecil River, one of the two branches in the lower reach of the Kapuas River, showed higher levels and diagenesis of sedimentary organic matter due to input from anthropogenic sources and increased marine organic matter near the mouth. This study shows that different stretches along the river exhibit different levels and composition of sedimentary organic matter, as well as different carbon dynamics, which is directly attributable to the varying landscapes and quality of organic matter.

  20. Dark Matter is Baryons

    Soberman, R K; Soberman, Robert K.; Dubin, Maurice


    A comet-like, but magnitudes smaller, extremely low albedo interstellar meteoroid population of fragile aggregates with solar type composition, measured in space and terrestrially, is most probably the universal dark matter. Although non-baryonic particles cannot be excluded, only "Big Bang" cosmology predicts an appreciable fraction of such alternate forms. As more counter-physics hypotheses are added to fit observation to the expanding universe assumption, a classical physics alternative proffers dark matter interactive red shifts normally correlated with distance. The cosmic microwave background results from size-independent thermal plateau radiation that emanates from dark matter gravitationally drawn into the Galaxy.

  1. Dark Matter 2014

    Schumann Marc


    Full Text Available This article gives an overview on the status of experimental searches for dark matter at the end of 2014. The main focus is on direct searches for weakly interacting massive particles (WIMPs using underground-based low-background detectors, especially on the new results published in 2014. WIMPs are excellent dark matter candidates, predicted by many theories beyond the standard model of particle physics, and are expected to interact with the target nuclei either via spin-independent (scalar or spin-dependent (axial-vector couplings. Non-WIMP dark matter candidates, especially axions and axion-like particles are also briefly discussed.

  2. Physics of condensed matter

    Misra, Prasanta K


    Physics of Condensed Matter is designed for a two-semester graduate course on condensed matter physics for students in physics and materials science. While the book offers fundamental ideas and topic areas of condensed matter physics, it also includes many recent topics of interest on which graduate students may choose to do further research. The text can also be used as a one-semester course for advanced undergraduate majors in physics, materials science, solid state chemistry, and electrical engineering, because it offers a breadth of topics applicable to these majors. The book be

  3. Dark matter in voids

    Fong, Richard; Doroshkevich, Andrei G.; Turchaninov, Victor I.


    The theory of the formation of large-scale structure in the universe through the action of gravitational instability imply the existence of substantial amounts of baryonic dark matter, of the order of 50% of the total baryon content in the universe, in the ``voids'' or under-dense regions seen in the large-scale distribution of galaxies. We discuss also the large-scale structure of dark matter expected in voids and the present and future possibilities for the observation of this baryonic dark matter in ``voids.''

  4. Dark matter in voids

    Fong, R. [Department of Physics, University of Durham, Durham, DH1 3LE (United Kingdom); Doroshkevich, A.G. [Keldysh Institute of Applied Mathematics, 125047 Moscow (Russian Federation)]|[Teoretical Astrophysics Centrum, Blegsdamsvej 17, Copenhagen DK 2100 (Denmark); Turchaninov, V.I. [Keldysh Institute of Applied Mathematics, 125047 Moscow (Russian Federation)


    The theory of the formation of large-scale structure in the universe through the action of gravitational instability imply the existence of substantial amounts of baryonic dark matter, of the order of 50% of the total baryon content in the universe, in the ``voids`` or under-dense regions seen in the large-scale distribution of galaxies. We discuss also the large-scale structure of dark matter expected in voids and the present and future possibilities for the observation of this baryonic dark matter in ``voids.`` {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  5. Dark Matter in ATLAS

    Resconi, Silvia; The ATLAS collaboration


    Results of Dark Matter searches in mono-X analysis with the ATLAS experiment at the Large Hadron Collider are reported. The data were collected in proton–proton collisions at a centre-of-mass energy of 13 TeV and correspond to an integrated luminosity of 3.2 fb-1. A description of the main characteristics of each analysis and how the main backgrounds are estimated is shown. The observed data are in agreement with the expected Standard Model backgrounds for all analysis described. Exclusion limits are presented for Dark Matter models including pair production of dark matter candidates.

  6. Enabling Forbidden Dark Matter

    Cline, James; Liu, Hongwan; Slatyer, Tracy; Xue, Wei


    The thermal relic density of dark matter is conventionally set by two-body annihilations. We point out that in many simple models, $3 \\to 2$ annihilations can play an important role in determining the relic density over a broad range of model parameters. This occurs when the two-body annihilation is kinematically forbidden, but the $3\\to 2$ process is allowed; we call this scenario "Not-Forbidden Dark Matter". We illustrate this mechanism for a vector portal dark matter model, showing that fo...

  7. Dark Matter 2014

    Schumann, Marc


    This article gives an overview on the status of experimental searches for dark matter at the end of 2014. The main focus is on direct searches for weakly interacting massive particles (WIMPs) using underground-based low-background detectors, especially on the new results published in 2014. WIMPs are excellent dark matter candidates, predicted by many theories beyond the standard model of particle physics, and are expected to interact with the target nuclei either via spin-independent (scalar) or spin-dependent (axial-vector) couplings. Non-WIMP dark matter candidates, especially axions and axion-like particles are also briefly discussed.

  8. Documenting the Distribution and Sedimentology of the Penultimate Tsunami Along a Cross Island Transect on Koh Phra Thong Island, Thailand

    Kirby, M. E.; Rhodes, B. P.; Leeper, R. J.; Choowong, M.


    Thailand's Koh Phra Thong Island is characterized by ridge-swale topography. Unlike the ridges, swales often hold water during the wet season, which allows for the deposition and preservation of sediment. As a result, swales are potential archives for past tsunami deposits. Seven different swale sites along a 1.9 km transect on the northern half of the island were trenched to investigate the occurrence and distribution of paleo-tsunami deposits. Duplicate overlapping slab cores were taken from the trench walls. Cores from sites F111, F511, F611, and F811 were analyzed at 1 cm contiguous intervals for magnetic susceptibility, percent organic matter, percent total carbonate, and grain size. Each site contained at least one distinct penultimate tsunami (PT) unit. Although the quality of preservation of the PT sediment unit diminishes with distance from the modern shoreline, presumably caused by differential bioturbation, grain size distributions and organic matter content clearly demarcate each PT unit. Notably, the distribution of sand sizes throughout the PT is not the same landward. More distal sites (F611 and F811) are dominated by very fine to fine sands; whereas, the mid island site (F511) is sand and coarse sand dominated. Microscopic charcoal was picked under a binocular scope to bracket the PT unit. A maximum age of 620 cy BP was obtained for the most distal site (F811). Ages spanning 740 - 900 cy BP provide a maximum age for the PT unit at F511. Ages for the PT unit from near the present day shoreline are similar (550 - 770 cy BP: Jankaew et al., 2008) using radiocarbon methods. OSL dates from the PT unit sands show an age 380×50 years before AD 1950 (Prendergast et al., 2012). From these various ages, the PT unit was deposited no earlier than 900 cy BP but likely no later than 380×50 years before AD 1950.

  9. Scalar Field Dark Matter

    Matos, T; Urena-Lopez, L A; Núñez, D


    This work is a review of the last results of research on the Scalar Field Dark Matter model of the Universe at cosmological and at galactic level. We present the complete solution to the scalar field cosmological scenario in which the dark matter is modeled by a scalar field $\\Phi$ with the scalar potential $V(\\Phi)=V_{0}(cosh {(\\lambda \\sqrt{\\kappa_{0}}\\Phi)}-1)$ and the dark energy is modeled by a scalar field $\\Psi$, endowed with the scalar potential $\\tilde{V}(\\Psi)= \\tilde{V_{0}}(\\sinh{(\\alpha \\sqrt{\\kappa_{0}}\\Psi)})^{\\beta}$, which together compose the 95% of the total matter energy in the Universe. The model presents successfully deals with the up to date cosmological observations, and is a good candidate to treat the dark matter problem at the galactic level.

  10. Superheavy dark matter

    Chung, Daniel J.H.; Riotto, Antonio; Chung, Daniel J. H.; Kolb, Edward W.; Riotto, Antonio


    We show that, contrary to the standard lore, dark matter may be superheavy (many orders of magnitude larger than the weak scale). We show that massive particles may be produced naturally during the transition from the inflationary phase to either a matter-dominated or radiation-dominated phase as a result of the expansion of the background spacetime acting on vacuum quantum fluctuations of the dark matter field. We find that as long as there are stable particles whose mass is of the order of the inflaton mass (presumably around 10^13 GeV), they will be produced in sufficient abundance to give Omega_0=1 quite independently of any details of the non-gravitational interactions of the dark-matter field.

  11. Boiling Primordial Matter: 1968

    Hagedorn, Rolf


    This introductory article presents in popular language how the view of the early Universe was evolving through 1968 under the influence of than new and recent insights about the thermodynamic properties of strongly interacting matter (by JR, editor).

  12. The Heart of Matter

    Godbole, Rohini M


    In this article I trace the development of the human understanding of the "Heart of Matter" from early concepts of "elements" (or alternatively "Panchmahabhootas") to the current status of "quarks" and "leptons" as the fundamental constituents of matter, interacting together via exchange of the various force carrier particles called "gauge bosons" such as the photon, W/Z-boson etc. I would like to show how our understanding of the fundamental constituents of matter has gone hand in hand with our understanding of the fundamental forces in nature. I will also outline how the knowledge of particle physics at the "micro" scale of less than a Fermi(one millionth of a nanometer), enables us to offer explanations of Cosmological observations at the "macro" scale. Consequently these observations, may in turn, help us address some very fundamental questions of the Physics at the "Heart of the Matter".

  13. 妙用matter



    matter一词用法灵活,既可以作名词,也可作动词。一、matter作名词,主要有以下三种意思:1.事情;问题。作复数时可意为"事态,情况"。例如:It is a matter of importance.这事很重要。How did matters stand?情况怎么样?2.物质。例如:The world is made up of matter.世界是由物质构成的。3.要紧事。例如:It makes no matter whether you come or not.你来不来都无关紧要。

  14. Cleaning up dark matter

    Bignami, Giovanni Fabrizio


    "An experiment in Italy has found tantalizing but puzzling evidence for axions, one if the leading candidates for dark matter. The authors explain how a pair of spinning neutron stars should settle the issue once and for all." (3 pages)

  15. Analysing soft matter

    Tom McLeish


    Full Text Available A new volume on soft materials ranges broadly across systems and techniques, experiment, and theory. Despite a lack of coherence, there is much of interest, which conveys the energy within soft-matter science, says

  16. Matter Tracking Information System -

    Department of Transportation — The Matter Tracking Information System (MTIS) principle function is to streamline and integrate the workload and work activity generated or addressed by our 300 plus...

  17. The Study of Matter.

    Campbell, Peter


    Reviews the booklet "The Study of Matter" produced by the Institute of Physics as part of their Shaping the Future series. This booklet is designed for teachers of chemistry, physics, design and technology, and biology. (Author/CCM)

  18. Expiration Dates Matter

    Full Text Available ... Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products For Consumers Home For Consumers Consumer Updates Expiration Dates Matter ... Should Know CDER FOIA Electronic Reading Room Related Consumer Updates How to Dispose of Unused Medicines Identifying ...

  19. Inflatable Dark Matter.

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D


    We describe a general scenario, dubbed "inflatable dark matter," in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early Universe. The overproduction of dark matter that is predicted within many, otherwise, well-motivated models of new physics can be elegantly remedied within this context. Thermal relics that would, otherwise, be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the nonthermal abundance of grand unified theory or Planck scale axions can be brought to acceptable levels without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ∼MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the standard model.

  20. Dark matter warms up

    Peplow, Mark


    "Unseen mass looks to be more "tepid" than thought. Astronomers have measured the temperature of dark matter for the first time. The discovery should help particle hunters to identify exactly what this mysterious substance is made of" (1 page)

  1. Dynamics of Soft Matter

    García Sakai, Victoria; Chen, Sow-Hsin


    Dynamics of Soft Matter: Neutron Applications provides an overview of neutron scattering techniques that measure temporal and spatial correlations simultaneously, at the microscopic and/or mesoscopic scale. These techniques offer answers to new questions arising at the interface of physics, chemistry, and biology. Knowledge of the dynamics at these levels is crucial to understanding the soft matter field, which includes colloids, polymers, membranes, biological macromolecules, foams, emulsions towards biological & biomimetic systems, and phenomena involving wetting, friction, adhesion, or micr

  2. Elastically Decoupling Dark Matter

    Kuflik, Eric; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai


    We present a novel dark matter candidate, an Elastically Decoupling Relic (ELDER), which is a cold thermal relic whose present abundance is determined by the cross-section of its elastic scattering on Standard Model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross-section with electrons, photons and/or neutrinos in the $10^{-3}-1$ fb range.

  3. Matter from Toric Geometry

    Candelas, Philip; Rajesh, G; Candelas, Philip; Perevalov, Eugene; Rajesh, Govindan


    We present an algorithm for obtaining the matter content of effective six-dimensional theories resulting from compactification of F-theory on elliptic Calabi-Yau threefolds which are hypersurfaces in toric varieties. The algorithm allows us to read off the matter content of the theory from the polyhedron describing the Calabi-Yau manifold. This is based on the generalized Green-Schwarz anomaly cancellation condition.

  4. Elastically Decoupling Dark Matter.

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai


    We present a novel dark matter candidate, an elastically decoupling relic, which is a cold thermal relic whose present abundance is determined by the cross section of its elastic scattering on standard model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross section with electrons, photons and/or neutrinos in the 10^{-3}-1  fb range.

  5. Alternatives to Dark Matter (?)

    Aguirre, Anthony


    It has long been known that Newtonian dynamics applied to the visible matter in galaxies and clusters does not correctly describe the dynamics of those systems. While this is generally taken as evidence for dark matter it is in principle possible that instead Newtonian dynamics (and with it General Relativity) breaks down in these systems. Indeed there have been a number of proposals as to how standard gravitational dynamics might be modified so as to correctly explain galactic dynamics witho...

  6. Sedimentology and stratigraphy of the middle Eocene Guara carbonate platform near Arguis, South-West Pyrenean foreland: Implications for basin physiography

    Huyghe, D.; Castelltort, S.; Serra-Kiel, J.; Filleaudeau, P.-Y.; Emmanuel, L.; Mouthereau, F.; Renard, M.


    The Pyrenees results from the collision between Spain and Europe and developed between the upper Cretaceous (Santonian) and the Miocene. Its foreland basins are characterised by a thick fill of detrital and carbonate sediments. The diversity of Eocene deposits in the southern Pyrenean foreland basin is of particular use in facies sedimentology due to their exceptional outcropping quality and well established stratigraphic framework and has been taken as type examples of many different sedimentary environments. Most studies have concerned facies sedimentology of detrital series in turbiditic environments, meandering and braided rivers, alluvial fans, and deltas. In contrast, the Eocene carbonate series have attracted less attention. The marine Guara limestones are a formation of lower to middle Eocene age deposited on the southern border of the western Pyrenean foreland basin (Jaca basin). They were deposited as a retrogradational carbonate platform dominated by large benthic foraminifers near or at the flexural forebulge of the foreland basin as the Pyrenean orogen developed. This formation represents the last episode of carbonate platform in the Pyrenees and remains poorly studied. In the present work our aim is to provide a detailed facies analysis and physiographic reconstructions of the Guara carbonate platform. This is crucial to unravel the respective influences of tectonics, climate and rheology of the lithosphere on the foreland basin tectonic and stratigraphic development, and it brings new constraints on the paleoenvironments and paleogeography during the Lutetian, i.e. at the beginning of the major phase of activity of the Pyrenean orogenesis. Two outcrops were studied in the Sierras Marginales at the localities of Arguis and Lusera. The Lusera section once restored in its initial position is located to the North of the Arguis section in a basinward direction such that comparing time-equivalent facies between these two sections helps us reconstructing

  7. GUTzilla Dark Matter

    Harigaya, Keisuke; Lou, Hou Keong


    Motivated by gauge coupling unification and dark matter, we present an extension to the Standard Model where both are achieved by adding an extra new matter multiplet. Such considerations lead to a Grand Unified Theory with very heavy WIMPzilla dark matter, which has mass greater than ~10^7 GeV and must be produced before reheating ends. Naturally, we refer to this scenario as GUTzilla dark matter. Here we present a minimal GUTzilla model, adding a vector-like quark multiplet to the Standard Model. Proton decay constraints require the new multiplet to be both color and electroweak charged, which prompts us to include a new confining SU(3) gauge group that binds the multiplet into a neutral composite dark matter candidate. Current direct detection constraints are evaded due to the large dark matter mass; meanwhile, next-generation direct detection and proton decay experiments will probe much of the parameter space. The relic abundance is strongly dependent on the dynamics of the hidden confining sector, and we...

  8. High Density Matter

    Stone J.R.


    Full Text Available The microscopic composition and properties of matter at super-saturation densities have been the subject of intense investigation for decades. The scarcity of experimental and observational data has led to the necessary reliance on theoretical models. There remains great uncertainty in these models which, of necessity, have to go beyond the over-simple assumption that high density matter consists only of nucleons and leptons. Heavy strange baryons, mesons and quark matter in different forms and phases have to be included to fulfil basic requirements of fundamental laws of physics. In this contribution latest developments in construction of the Equation of State (EoS of high-density matter at zero and finite temperature assuming different composition of matter will be discussed. Critical comparison of model EoS with available experimental data from heavy ion collisions and observations on neutron stars, including gravitational mass, radii and cooling patterns and data on X-ray burst sources and low mass X-ray binaries are made. Fundamental differences between the EoS of low-density, high temperature matter, such as is created in heavy ion collisions and of high-density, low temperature compact objects is discussed.

  9. Baryons as dark matter

    Carr, B.J. [Queen Mary and Westfield Coll., London (United Kingdom). Astronomy Unit]|[Fermi National Accelerator Lab., Batavia, IL (United States). NASA/Fermilab Astrophysics Center


    Dark matter may reside in galactic disks, galactic halos, clusters of galaxies and the background Universe. Cosmological nucleosynthesis arguments suggest that only some fraction of the baryons in the Universe are in visible form, so at least some of the dark matter problems could be baryonic. The dark matter in galactic disks (if real) is almost certainly baryonic and, in this case, it is either in white dwarfs or brown dwarfs. The dark matter in galactic halos could be at least partly baryonic and, in this case, it is likely to be contained in the remnants of a first generation of pregalactic or protogalatic stars. The various constrains on the nature of such remnants suggest that brown dwarfs are the most plausible candidates, although (rather perplexingly) microlensing searches currently favor white dwarfs. The dark matter in clusters or intergalactic space could be baryonic only if one gives up the standard cosmological nucleosynthesis scenario or assumes that the dark objects are primordial black holes which formed before nucleosynthesis. If it is non-baryonic and in the form of cold WIMPs (Weakly Interacting Massive Particles), then such particles should also provide some of the halo dark matter. 89 refs., 1 fig., 2 tabs.

  10. Diagenesis of 1900-year-old siliceous sinter (opal-A to quartz) at Opal Mound, Roosevelt Hot Springs, Utah, U.S.A.

    Lynne, Bridget Y.; Campbell, Kathleen A.; Moore, J. N.; Browne, P. R. L.


    White, vitreous, siliceous sinter dated by 14C at ˜1900 years BP is located along the crest of the Opal Mound deposit at Roosevelt Hot Springs, Utah, U.S.A. Deposition at vents resulted from the Opal Mound fault opening conduits to the surface, allowing thermal fluids to discharge. Fault movement subsequently fractured the sinter and initiated a second period of fluid discharge. Colorful silica was deposited in this later period and formed the distal slope sinter, dated at ˜1600 years BP. The sinter preserves both end-members in the mineralogical maturation of silica, from initial opal-A to mature quartz, and also records incremental intermediate steps, as revealed by X-ray powder diffractrometry and by scanning electron, optical and Raman laser microscopy. Textural and mineralogical changes from one silica phase to another transpired gradually and gradationally. During diagenesis, incremental morphological changes alternated three times through nano- to micro-particle size transitions. The three corresponding mineralogical steps comprise: (1) opal-A to opal-CT, (2) opal-CT to opal-C, and (3) opal-C to quartz. Mineralogical changes preceded all morphological changes. Each step was initiated when silica nanostructures reached a critical diameter of 200 nm. The initial starting point of fresh (modern), polymeric, siliceous sinter deposition worldwide is nano-spherical particles of colloidal opal-A. Opaline sinter at Opal Mound is slightly more mature, reflecting the beginning of the aging process, and comprises botryoidal clusters of silica microspheres (quartz formation, the opal-C nano-rods recrystallize into groups of blocky nanostructures, each up to 200 × 300 nm. Quartz crystals grow at the expense of and pseudomorph opal-C, shown by remnant bands of blocky nanostructures at the base of the quartz crystals. Two generations of quartz crystals occur at Opal Mound: (1) diagenetic, which developed as opal-C nanostructures recrystallize to quartz; and (2

  11. Geothermal prospection in the Greater Geneva Basin (Switzerland and France). Impact of diagenesis on reservoir properties of the Upper Jurassic carbonate sediments

    Makhloufi, Yasin; Rusillon, Elme; Brentini, Maud; Clerc, Nicolas; Meyer, Michel; Samankassou, Elias


    Diagenesis of carbonate rocks is known to affect the petrophysical properties (porosity, permeability) of the host rock. Assessing the diagenetic history of the rock is thus essential when evaluating any reservoir exploitation project. The Canton of Geneva (Switzerland) is currently exploring the opportunities for geothermal energy exploitation in the Great Geneva Basin (GGB) sub-surface. In this context, a structural analysis of the basin (Clerc et al., 2016) associated with reservoir appraisal (Brentini et al., 2017) and rock-typing of reservoir bodies of potential interest were conducted (Rusillon et al., 2017). Other geothermal exploitation projects elsewhere (e.g. Bavaria, south Germany, Paris Basin, France) showed that dolomitized carbonate rocks have good reservoir properties and are suitable for geothermal energy production. The objectives of this work are to (1) describe and characterize the dolomitized bodies in the GGB and especially their diagenetic history and (2) quantify the reservoir properties of those bodies (porosity, permeability). Currently, our study focuses on the Upper Jurassic sedimentary bodies of the GGB. Field and well data show that the dolomitization is not ubiquitous in the GGB. Results from the petrographical analyses of the Kimmeridgian cores (Humilly-2) and of field analogues (Jura, Saleve and Vuache mountains) display complex diagenetic histories, dependent of the study sites. The paragenesis exhibits several stages of interparticular calcite cementation as well as different stages of dolomitization and/or dedolomitization. Those processes seem to follow constrained path of fluid migrations through burial, faulting or exhumation during the basin's history. These complex diagenetic histories affected the petrophysical and microstructural properties via porogenesis (conservation of initial porosity, moldic porosity) and/or poronecrosis events. The best reservoir properties appear to be recorded in patch reef and peri

  12. Holocene paleoclimate history of Fallen Leaf Lake, CA., from geochemistry and sedimentology of well-dated sediment cores

    Noble, Paula J.; Ball, G. Ian; Zimmerman, Susan H.; Maloney, Jillian; Smith, Shane B.; Kent, Graham; Adams, Kenneth D.; Karlin, Robert E.; Driscoll, Neal


    Millennial-scale shifts in aridity patterns have been documented during the Holocene in the western United States, yet the precise timing, severity, and regional extent of these shifts prompts further study. We present lake sediment core data from Fallen Leaf Lake, a subalpine system at the southern end of the Lake Tahoe basin for which 80% of the contemporary inflow is derived from snowpack delivered by Pacific frontal storm systems. A high quality age model has been constructed using 14C ages on plant macrofossils, 210Pb, and the Tsoyowata tephra datum (7.74-7.95 cal kyr BP). One core captures the transition from the Late Tioga-younger Dryas glaciolacustrine package to laminated opaline clay at 11.48 cal kyr BP. Early Holocene sedimentation rates are relatively high (∼1.9 mm/year) and cooler winter temperatures are inferred by the presence of pebbles interpreted to be transported out into the lake via shore ice. There is a geochemically distinct interval from ∼4.71 to 3.65 cal kyr BP that is interpreted as a late Holocene neopluvial, characterized by depleted δ13C and lower C:N that point to reduced runoff of terrigenous organic matter, increased winter precipitation, and increased algal productivity. The largest Holocene signal in the cores occurs at the end of the neopluvial, at 3.65 cal kyr BP, and marks a shift into a climate state with variable precipitation, yet is overall more arid than the neopluvial. This new climate state persists for ∼3 ka, until the Little Ice Age. Low sedimentation rates (0.5 mm/year), the homogeneous opaline sediment, and steadily increasing contributions of terrestrial vs. algal organic matter in these cores suggest that the lowstand state of Fallen Leaf Lake may have been the norm from 3.65 to 0.55 cal kyr BP, punctuated by short term high precipitation years or multi-year intervals capable of rapid short duration lake level rise. Fallen Leaf Lake is strongly influenced by changes in winter precipitation and temperature

  13. Miocene alluvial fan-alkaline playa lignite-trona bearing deposits from an inverted basin in Anatolia: sedimentology and tectonic controls on deposition

    İnci, Uǧur


    During the Middle through Late Miocene, over 1200 m of clastics, carbonates and evaporites accumulated in the depositional basin situated in northwestern Ankara province of Central Anatolia. Detailed stratigraphic and sedimentological analyses of the exposed sequence exhibits three major facies: (1) lower alluvial, (2) upper alluvial, and (3) lacustrine. The lower alluvial facies consists primarily of volcaniclastic debris-flow, boulder and channel conglomerate, sandstone, siltstone, mudstone and two lignite horizons. These rock assemblages were deposited in alluvial fans and a braided-river system. The lower and upper lignite seams were laid down in swamps and lake-margin mud-flat environments associated with this river system. The upper alluvial facies is characterized by red conglomerate, fine-grained and cross-bedded sandstone, mudstone and calcareous mudstone units. The dominant depositional environments are interpreted to be alluvial fan, braided-river, and mud-flat. The base of the lacustrine deposits interfingers with the lower alluvial facies and consists of dolomitic claystone, bituminous shale, trona and intraformational conglomerate lithofacies. The sedimentary features of the dolomitic claystone and trona lithofacies suggest deposition in a playa-lake type environment. The bituminous shale is a transgressive deposit laid down in a shallow, but expanded lake environment. Sedimentological and structural characteristics of the intraformational conglomerate lithofacies indicate synsedimentary tectonism, intrabasinal erosion, redeposition and sediment selection toward the deposition centre of the lake environment. The green claystone lithofacies has three units: (a) the claystone-bedded chert-analcitized tuff alternation and siliceous carbonate lithofacies of the lacustrine system, deposited in a perennial lake environment; (b) montmorillonitic olive-green claystone containing mud-cracks, ripple mark and desiccation cracks filled by gypsum, deposited in a

  14. Integrated sedimentological and ichnological characteristics of a wave-dominated, macrotidal coast: a case study from the intertidal shoreface of the Dongho coast, southwest Korea

    Yang, Byong Cheon; Chang, Tae Soo


    Generalized coastal facies models invariably assume that tidal flats and intertidally exposed shorefaces along macrotidal coasts are tide-dominated. Recent advances in coastal sedimentology, however, have revealed that wave-dominated macrotidal flats also occur in a wide range of coastal settings, in particular where tidal modulation forces the lateral translation of the wave-affected zone across the tidally exposed shoreface with the rising tide. Despite tidal modulation, the depositional character in the latter case (abundant storm deposits) exhibits a high degree of similarity with conventional subtidal shorefaces, implying that it is inherently difficult to distinguish between the two coastal systems in the rock record. In the present study, integrated sedimentological and ichnological data from the Dongho coast, which is located along the southwest coast of Korea, provide valuable information for the establishment of facies criteria that can assist in the recognition of such coastal deposits. In fact, the sedimentary character of the study area, which is dominated by an abundance of wave-formed structures, resembles that generally associated with subtidal shorefaces. In addition, the depositional processes responsible for sediment accumulation are, in the present case, also strongly influenced by pronounced seasonal variations in wave energy. In this context, the study has revealed a number of major features that appear to be characteristic of wave-dominated intertidal flats and shorefaces: (1) firmground muds may be encountered on the beach face, where intense swash-backwash motions are dominant; (2) the thickness of storm deposits decreases landward, reflecting the progressive decrease in wave energy; (3) ichnologically, there is an offshore shift in the dominance of trace fossils from the Skolithos ichnofacies, including Ophiomorpha, Thalassinoides and Psilonichnus, to a proximal expression of the Cruziana ichnofacies, which includes Siphonichnus and

  15. Diagenesis of clastic rock of Palaeozoic and its influence on reservoir in Tazhong area, Tarim basin%塔中地区古生界碎屑岩成岩作用及其对储层的影响

    徐燕军; 于炳松; 钟大康


      通过取心井常规薄片、铸体薄片、扫描电镜、X 衍射等资料的分析,研究了塔里木盆地塔中地区古生界碎屑岩成岩作用及其对储层发育的影响。研究结果显示,研究区碎屑岩储层处于中成岩 A 期,且经历的主要成岩作用有压实与压溶作用、胶结作用、溶蚀作用、交代作用和重结晶作用等。另外,这些成岩作用对储集层孔隙发育及储层性质具有明显的影响:压实与压溶作用、交代、胶结作用、石英长石的次生加大以及重结晶作用使储层孔隙体积减小、物性变差,如压实与压溶作用使本区储层孔隙度损失14.1%~25.3%,交代、胶结作用使孔隙度损失13.9%;溶蚀作用是增加储集空间、改善储层物性最重要的成岩作用,如石英、长石及岩屑颗粒的溶蚀作用使储层产生次生孔隙,导致本区储层孔隙度平均增加6%~8%。%  Based on the full analysis of the data such as conventional section, cast section, X-ray diffraction and SEM, the Paleaozoic clastic diagenesis and its influence on clastic reservoir development in Tazhong area have been studied. The results of the study indicate that the clastic reservoir is in the stage A of middle diagenesis and the major diagenesis includes compaction, cementation(siliceous cementation, carbonate cementation and hydro-syalite cementation), dissolution(feldspar, minor debris and carbonate cement), alternation and fracture along with the sedimentary and diagenesis history. These diagenism has markedly influenced the pore development and physical properties of the reservoir. The mechanical compaction, the subsequent volcanism of quartz and feldspar has destructive influence on the physical properties of the reservoir. Compaction and pressure solution have in-duced the decrease in porosity(14.1%~25.3% ), the cement has filled up and blocked the pore throat of sandstone in various ways; Secondary overgrowth of quartz could

  16. Sedimentary process control on carbon isotope composition of sedimentary organic matter in an ancient shallow-water shelf succession

    Davies, S. J.; Leng, M. J.; Macquaker, J. H. S.; Hawkins, K.


    Source and delivery mechanisms of organic matter are rarely considered when interpreting changing δ13C through sedimentary successions even though isotope excursions are widely used to identify and correlate global perturbations in the carbon cycle. Combining detailed sedimentology and geochemistry we demonstrate how organic carbon abundance and δ13C values from sedimentary organic matter from Carboniferous-aged mudstones are influenced by the proportion of terrestrial versus water column-derived organic matter. Silt-bearing clay-rich shelf mudstones that were deposited by erosive density flows are characterized by 1.8-2.4% organic carbon and highδ13C values (averaging -22.9 ± 0.3‰, n = 12). Typically these mudstones contain significant volumes of terrestrial plant-derived material. In contrast, clay-rich lenticular mudstones, with a marine macrofauna, are the products of the transport of mud fragments, eroded from pre-existing water-rich shelfal muds, when shorelines were distant and biological productivity in the water column was high. Higher organic carbon (2.1-5.2%) and lowerδ13C values (averaging -24.3 ± 0.5‰, n = 11) characterize these mudstones and are interpreted to reflect a greater contribution by (isotopically more negative) amorphous organic matter derived from marine algae. Differences in δ13C between terrestrial and marine organic matter allow the changing proportions from different sources to be tracked through this succession. Combining δ13C values with zirconium (measured from whole rock), here used as a proxy for detrital silt input, provides a novel approach to distinguishing mudstone provenance and ultimately using δ13C to identify oil-prone organic matter in potential source rocks. These results have important implications for using bulk organic matter to identify and characterize global C-isotope excursions.

  17. Sedimentological evidence for a deltaic origin of the western fan deposit in Jezero crater, Mars and implications for future exploration

    Goudge, Timothy A.; Milliken, Ralph E.; Head, James W.; Mustard, John F.; Fassett, Caleb I.


    We examine the stratigraphic architecture and mineralogy of the western fan deposit in the Jezero crater paleolake on Mars to reassess whether this fan formed as a delta in a standing body of water, as opposed to by alluvial or debris flow processes. Analysis of topography and images reveals that the stratigraphically lowest layers within the fan have shallow dips (<2°), consistent with deltaic bottomsets, whereas overlying strata exhibit steeper dips (∼2-9°) and downlap, consistent with delta foresets. Strong clay mineral signatures (Fe/Mg-smectite) are identified in the inferred bottomsets, as would be expected in the distal fine-grained facies of a delta. We conclude that the Jezero crater western fan deposit is deltaic in origin based on the exposed stratal geometries and mineralogy, and we emphasize the importance of examining the stratigraphic architecture of sedimentary fan deposits on Mars to confidently distinguish between alluvial fans and deltas. Our results indicate that Jezero crater contains exceptionally well-preserved fluvio-deltaic stratigraphy, including strata interpreted as fine-grained deltaic bottomsets that would have had a high potential to concentrate and preserve organic matter. Future exploration of this site is both geologically and astrobiologically compelling, and in situ analyses would be complementary to the ongoing in situ characterization of fluvio-lacustrine sediment in the Gale crater paleolake basin by the Curiosity rover.

  18. Redox-controlled preservation of organic matter during "OAE 3" within the Western Interior Seaway

    Tessin, Allyson; Hendy, Ingrid; Sheldon, Nathan; Sageman, Bradley


    During the Cretaceous, widespread black shale deposition occurred during a series of Oceanic Anoxic Events (OAEs). Multiple processes are known to control the deposition of marine black shales, including changes in primary productivity, organic matter preservation, and dilution. OAEs offer an opportunity to evaluate the relative roles of these forcing factors. The youngest of these events—the Coniacian to Santonian OAE 3—resulted in a prolonged organic carbon burial event in shallow and restricted marine environments including the Western Interior Seaway. New high-resolution isotope, organic, and trace metal records from the latest Turonian to early Santonian Niobrara Formation are used to characterize the amount and composition of organic matter preserved, as well as the geochemical conditions under which it accumulated. Redox sensitive metals (Mo, Mn, and Re) indicate a gradual drawdown of oxygen leading into the abrupt onset of organic carbon-rich (up to 8%) deposition. High Hydrogen Indices (HI) and organic carbon to total nitrogen ratios (C:N) demonstrate that the elemental composition of preserved marine organic matter is distinct under different redox conditions. Local changes in δ13C indicate that redox-controlled early diagenesis can also significantly alter δ13Corg records. These results demonstrate that the development of anoxia is of primary importance in triggering the prolonged carbon burial in the Niobrara Formation. Sea level reconstructions, δ18O results, and Mo/total organic carbon ratios suggest that stratification and enhanced bottom water restriction caused the drawdown of bottom water oxygen. Increased nutrients from benthic regeneration and/or continental runoff may have sustained primary productivity.

  19. Investigation of water-soluble organic matter extracted from shales during leaching experiments

    Zhu, Yaling; Vieth-Hillebrand, Andrea; Wilke, Franziska D. H.; Horsfield, Brian


    The huge volumes and unknown composition of flowback and produced waters cause major public concerns about the environmental and social compatibility of hydraulic fracturing and the exploitation of gas from unconventional reservoirs. Flowback and produced waters contain not only residues of fracking additives but also chemical species that are dissolved from the shales themselves during fluid-rock interaction. Knowledge of the composition, size and structure of dissolved organic carbon (DOC) as well as the main controls on the release of DOC are a prerequisite for a better understanding of these interactions and its effects on composition of flowback and produced water. Black shales from four different geological settings and covering a maturity range Ro = 0.3-2.6% were extracted with deionized water. The DOC yields were found to decrease rapidly with increasing diagenesis and remain low throughout catagenesis. Four DOC fractions have been qualitatively and quantitatively characterized using size-exclusion chromatography. The concentrations of individual low molecular weight organic acids (LMWOA) decrease with increasing maturity of the samples except for acetate extracted from the overmature Posidonia shale, which was influenced by hydrothermal brines. The oxygen content of the shale organic matter also shows a significant influence on the release of organic acids, which is indicated by the positive trend between oxygen index (OI) and the concentrations of formate and acetate. Based on our experiments, both the properties of the organic matter source and the thermal maturation progress of the shale organic matter significantly influence the amount and quality of extracted organic compounds during the leaching experiments.

  20. A Dark Matter Superfluid

    Khoury, Justin


    In this talk we present a novel framework that unifies the stunning success of MOND on galactic scales with the triumph of the LambdaCDM model on cosmological scales. This is achieved through the rich and well-studied physics of superfluidity. The dark matter and MOND components have a common origin, representing different phases of a single underlying substance. In galaxies, dark matter thermalizes and condenses to form a superfluid phase. The superfluid phonons couple to baryonic matter particles and mediate a MOND-like force. Our framework naturally distinguishes between galaxies (where MOND is successful) and galaxy clusters (where MOND is not): dark matter has a higher temperature in clusters, and hence is in a mixture of superfluid and normal phase. The rich and well-studied physics of superfluidity leads to a number of striking observational signatures, which we briefly discuss. Remarkably the critical temperature and equation of state of the dark matter superfluid are similar to those of known cold at...

  1. Vectorlike sneutrino dark matter

    Tang, Yi-Lei; Zhu, Shou-hua


    In this paper, we discuss the minimal supersymmetric standard model (MSSM) extended with one vectorlike lepton doublet L -L ¯ and one right-handed neutrino N . The neutral vecotorlike sneutrino can be a candidate of dark matter. To avoid the interaction with the nucleons by exchanging a Z boson, the mass splitting between the real part and the imaginary part of the sneutrino field is needed. Compared with the MSSM sneutrino dark matter, the mass splitting between the vectorlike sneutrino field can be more naturally acquired without large A terms and constraints on the neutralino masses. We have also calculated the relic density and the elastic scattering cross sections with the nucleons in the cases that the dark matter particles coannihilate with or without the MSSM slepton doublets. The elastic scattering cross sections with the nucleons are well below the LUX bounds. In the case that the dark matter coannihilates with all the MSSM slepton doublets, the mass of the dark matter can be as light as 370 GeV.

  2. Dark Matter Superfluidity

    Khoury, Justin


    In this talk I summarize a novel framework that unifies the stunning success of MOND on galactic scales with the triumph of the $\\Lambda$CDM model on cosmological scales. This is achieved through the rich and well-studied physics of superfluidity. The dark matter and MOND components have a common origin, representing different phases of a single underlying substance. In galaxies, dark matter thermalizes and condenses to form a superfluid phase. The superfluid phonons couple to baryonic matter particles and mediate a MOND-like force. This framework naturally distinguishes between galaxies (where MOND is successful) and galaxy clusters (where MOND is not): dark matter has a higher temperature in clusters, and hence is in a mixture of superfluid and normal phase. The rich and well-studied physics of superfluidity leads to a number of striking observational signatures, which we briefly discuss. Remarkably the critical temperature and equation of state of the dark matter superfluid are similar to those of known co...

  3. Asymmetric condensed dark matter

    Aguirre, Anthony; Diez-Tejedor, Alberto


    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate must be lighter than a few tens of eV so that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of decoupling to the scale of the QCD phase transition or above. This requires large dark matter-to-photon ratios and very weak interactions with standard model particles.

  4. Sedimentological interpretation and stratigraphical position of glacigenic deposits in the Napęków area (Holy Cross Mountains, Poland

    Ludwikowska-Kędzia Małgorzata


    Full Text Available The identification of depositional conditions and stratigraphical position of glacigenic deposits in the Napęków area is important for the genetic and stratigraphical interpretation of Quaternary deposits in the central part of the Holy Cross Mountains, as well as for a revision of the course and extent of Middle Polish (Saalian glaciations. These deposits comprise a series of diamictons which occur between sandy-gravelly deposits. Based on results of macro- and microscopic sedimentological investigations, analysis of heavy mineral composition, roundness and frosting of quartz grains, as well as OSL dating, this complex must have formed during the Odranian Glaciation (Drenthe, Saalian, MIS 6. Sandy-gravelly deposits are of fluvioglacial and melt-out origin. Diamictons represent subglacial traction till. Their facies diversity is a result of variations in time and space, complex processes of deposition and deformation, responsible for their formation at the base of the active ice sheet. This glacigenic depositional complex was transformed by erosion-denudation and aeolian processes in a periglacial environment during the Vistulian (Weichselian, MIS 5d-2.

  5. Chemostratigraphic and sedimentologic evolution of Wajid Group (Wajid Sandstone): An outcrop analog study from the Cambrian to Permian, SW Saudi Arabia

    Yassin, Mohamed A.; Abdullatif, Osman M.


    The Paleozoic age succession in Saudi Arabia represents one of the most prolific petroleum producing systems in the Arabian Peninsula. This succession is also considered important for unconventional tight gas and shale gas reservoirs. The Wajid Group (Wajid Sandstone) in SW Saudi Arabia consists of four formations, namely, Dibsiyah (Lower and Upper), Sanamah, Khusayyayn and Juwayl from bottom to top. This study investigates the major oxides, trace and rare earth elements for the Wajid Group formations in southwestern Saudi Arabia. We characterize and compare the sandstone types, provenance, tectonic setting, and climate. Moreover, we applied the chemostratigraphic technique for stratigraphic differentiation. Concentrations of certain elements indicate that Wajid Group was deposited in a passive continental margin. The geochemical analysis reveals that Wajid Group sediments were likely derived from the upper and bulk continental crust and mafic igneous provenance. The elemental geochemical data has been applied in this study to improve the stratigraphic subdivision and correlation. Using selected elements, geochemical vertical profiles, binary, and ternary diagrams allow clearly distinguishing between Wajid Group formations. Thus supports the established formation boundaries that constructed using lithostratigraphy and sedimentology. The geochemical elements variation between formations can be related to differences in rock-forming minerals, facies change, climate, and provenance. The results of this study may help in constraining and correlating complex facies strata and can be used as a guide for stratigraphic correlations in the subsurface within the Wajid basin and other equivalent stratigraphic successions within Saudi Arabia.

  6. Messinian events: new constraints from sedimentological investigations and new 40Ar/ 39Ar ages in the Melilla-Nador Basin (Morocco)

    Cornée, J. J.; Roger, S.; Münch, P.; Saint Martin, J. P.; Féraud, G.; Conesa, G.; Pestrea-Saint Martin, S.


    New 40Ar/ 39Ar ages obtained both from within a platform and from the adjacent basin allow, through the extension of a previous argon dataset, the establishment of a chronological framework for the Messinian carbonate complex of Melilla (Morocco). In the platform, prograding bioclastic deposits began around 6.87±0.02 Ma, whereas the youngest preserved deposits are 5.77±0.04 Ma old. The southern part of the basin was uplifted and emergent prior to 6.23±0.03 Ma. The Tortonian/Messinian and the Messinian/Pliocene boundaries have not yet been identified in the Melilla region. Durations of the prograding bioclastic deposits (ca. 410 ka), the prograding Porites reefs (ca. 360 ka) and the preserved part of the terminal carbonate complex (TCC) (ca. 330 ka) can be estimated. Sedimentological and geochronological investigations do not indicate any major subaerial unconformity nor any major time gap. If a major sea level fall did exist during Messinian times, it developed after 5.77±0.04 Ma. Chronological correlations show that the onset of the Sorbas gypsum deposition (Southern Spain), considered as the marker of the Messinian Salinity Crisis onset, is contemporaneous with aggrading Porites reef building of the terminal carbonate complex of Melilla. A major paleoceanographic change in the marginal areas of the Mediterranean, with the cessation of upwelling systems, could be partly coeval with the onset of the Messinian Salinity Crisis.

  7. Sedimentology, geochemistry, pollution status and ecological risk assessment of some heavy metals in surficial sediments of an Egyptian lagoon connecting to the Mediterranean Sea.

    El-Said, Ghada F; Draz, Suzanne E O; El-Sadaawy, Manal M; Moneer, Abeer A


    Spatial distribution of heavy metals (Co, Cu, Ni, Cr, Mn, Zn and Fe) was studied on Lake Edku's surface sediments in relation to sedimentology and geochemistry characteristics and their contamination status on the ecological system. Lake Edku's sediments were dominated by sandy silt and silty sand textures and were enriched with carbonate content (9.83-58.46%). Iron and manganese were the most abundant heavy metals with ranges of 1.69 to 8.06 mg g(-1) and 0.88 to 3.27 mg g(-1), respectively. Cobalt and nickel showed a harmonic distribution along the studied sediments. The results were interpreted by the statistical means. The heavy metal pollution status and their ecological risk in Lake Edku was evaluated using the sediment quality guidelines and the contamination assessment methods (geoaccumulation, pollution load and potential ecological risk indices, enrichment factor, contamination degree as well as effect range median (ERM) and probable effect level (PEL) quotients). Amongst the determined heavy metals, zinc had the most ecological risk. Overall, the heavy metals in surface sediments showed ecological effect range from moderate to considerable risk, specially, in the stations in front of the seawater and in drain sources that had the highest toxic priority.

  8. Sedimentological interpretation and stratigraphical position of glacigenic deposits in the Napęków area (Holy Cross Mountains, Poland)

    Ludwikowska-Kędzia, Małgorzata; Pawelec, Halina; Adamiec, Grzegorz


    The identification of depositional conditions and stratigraphical position of glacigenic deposits in the Napęków area is important for the genetic and stratigraphical interpretation of Quaternary deposits in the central part of the Holy Cross Mountains, as well as for a revision of the course and extent of Middle Polish (Saalian) glaciations. These deposits comprise a series of diamictons which occur between sandy-gravelly deposits. Based on results of macro- and microscopic sedimentological investigations, analysis of heavy mineral composition, roundness and frosting of quartz grains, as well as OSL dating, this complex must have formed during the Odranian Glaciation (Drenthe, Saalian, MIS 6). Sandy-gravelly deposits are of fluvioglacial and melt-out origin. Diamictons represent subglacial traction till. Their facies diversity is a result of variations in time and space, complex processes of deposition and deformation, responsible for their formation at the base of the active ice sheet. This glacigenic depositional complex was transformed by erosion-denudation and aeolian processes in a periglacial environment during the Vistulian (Weichselian, MIS 5d-2).

  9. The origin of dark matter, matter-anti-matter asymmetry, and inflation

    Mazumdar, Anupam


    A rapid phase of accelerated expansion in the early universe, known as inflation, dilutes all matter except the vacuum induced quantum fluctuations. These are responsible for seeding the initial perturbations in the baryonic matter, the non-baryonic dark matter and the observed temperature anisotropy in the cosmic microwave background (CMB) radiation. To explain the universe observed today, the end of inflation must also excite a thermal bath filled with baryons, an amount of baryon asymmetry, and dark matter. We review the current understanding of inflation, dark matter, mechanisms for generating matter-anti-matter asymmetry, and the prospects for testing them at ground and space based experiments.

  10. WISPy cold dark matter

    Arias, Paola [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Cadamuro, Davide; Redondo, Javier [Max-Planck-Institut fuer Physik, Muenchen (Germany); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Jaeckel, Joerg [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)


    Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches - exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques - can probe large parts of this parameter space in the foreseeable future. (orig.)

  11. Matter and memory

    Bergson, Henri


    Since the end of the last century," Walter Benjamin wrote, "philosophy has made a series of attempts to lay hold of the 'true' experience as opposed to the kind that manifests itself in the standardized, denatured life of the civilized masses. It is customary to classify these efforts under the heading of a philosophy of life. Towering above this literature is Henri Bergson's early monumental work, Matter and Memory."Along with Husserl's Ideas and Heidegger's Being and Time, Bergson's work represents one of the great twentieth-century investigations into perception and memory, movement and time, matter and mind. Arguably Bergson's most significant book, Matter and Memory is essential to an understanding of his philosophy and its legacy.This new edition includes an annotated bibliography prepared by Bruno Paradis.Henri Bergson (1859-1941) was awarded the Nobel Prize in 1927. His works include Time and Free Will, An Introduction to Metaphysics, Creative Evolution, and The Creative Mind.

  12. Natural minimal dark matter

    Fabbrichesi, Marco


    We show how the Higgs boson mass is protected from the potentially large corrections due to the introduction of minimal dark matter if the new physics sector is made supersymmetric. The fermionic dark matter candidate (a 5-plet of $SU(2)_L$) is accompanied by a scalar state. The weak gauge sector is made supersymmetric and the Higgs boson is embedded in a supersymmetric multiplet. The remaining standard model states are non-supersymmetric. Non vanishing corrections to the Higgs boson mass only appear at three-loop level and the model is natural for dark matter masses up to 15 TeV--a value larger than the one required by the cosmological relic density. The construction presented stands as an example of a general approach to naturalness that solves the little hierarchy problem which arises when new physics is added beyond the standard model at an energy scale around 10 TeV.

  13. Light, Matter, and Geometry

    Frisvad, Jeppe Revall

    Interaction of light and matter produces the appearance of materials. To deal with the immense complexity of nature, light and matter is modelled at a macroscopic level in computer graphics. This work is the first to provide the link between the microscopic physical theories of light and matter...... of a material and determine the contents of the material. The book is in four parts. Part I provides the link between microscopic and macroscopic theories of light. Part II describes how to use the properties of microscopic particles to compute the macroscopic properties of materials. Part III illustrates...... that we can use geometrical models to handle the large number of variables which appear when we construct appearance models from microscopic theories. Finally, Part IV provides detailed appearance models for natural water, ice, and milk to demonstrate how the theory is applied....

  14. Dark matter from unification

    Kainulainen, Kimmo; Tuominen, Kimmo; Virkajärvi, Jussi Tuomas


    We consider a minimal extension of the Standard Model (SM), which leads to unification of the SM coupling constants, breaks electroweak symmetry dynamically by a new strongly coupled sector and leads to novel dark matter candidates. In this model, the coupling constant unification requires...... eigenstates of this sector and determine the resulting relic density. The results are constrained by available data from colliders and direct and indirect dark matter experiments. We find the model viable and outline briefly future research directions....... the existence of electroweak triplet and doublet fermions singlet under QCD and new strong dynamics underlying the Higgs sector. Among these new matter fields and a new right handed neutrino, we consider the mass and mixing patterns of the neutral states. We argue for a symmetry stabilizing the lightest mass...

  15. Resonant SIMP dark matter

    Soo-Min Choi


    Full Text Available We consider a resonant SIMP dark matter in models with two singlet complex scalar fields charged under a local dark U(1D. After the U(1D is broken down to a Z5 discrete subgroup, the lighter scalar field becomes a SIMP dark matter which has the enhanced 3→2 annihilation cross section near the resonance of the heavier scalar field. Bounds on the SIMP self-scattering cross section and the relic density can be fulfilled at the same time for perturbative couplings of SIMP. A small gauge kinetic mixing between the SM hypercharge and dark gauge bosons can be used to make SIMP dark matter in kinetic equilibrium with the SM during freeze-out.

  16. Radiative light dark matter

    Dedes, A.; Karamitros, D.; Pilaftsis, A.


    We present a Peccei-Quinn (PQ)-symmetric two-Higgs doublet model that naturally predicts a fermionic singlet dark matter in the mass range 10 keV-1 GeV. The origin of the smallness of the mass of this light singlet fermion arises predominantly at the one-loop level, upon soft or spontaneous breakdown of the PQ symmetry via a complex scalar field in a fashion similar to the so-called Dine-Fischler-Sredniki-Zhitnitsky axion model. The mass generation of this fermionic radiative light dark matter (RLDM) requires the existence of two heavy vectorlike SU(2) isodoublets, which are not charged under the PQ symmetry. We show how the RLDM can be produced via the freeze-in mechanism, thus accounting for the missing matter in the Universe. Finally, we briefly discuss possible theoretical and phenomenological implications of the RLDM model for the strong C P problem and the CERN Large Hadron Collider (LHC).

  17. Dark Matter Candidates

    Baltz, E.


    It is now widely accepted that most of mass-energy in the universe is unobserved except by its gravitational effects. Baryons make only about 4% of the total, with ''dark matter'' making up about 23% and the ''dark energy'' responsible for the accelerated expansion of the universe making up the remainder. We focus on the dark matter, which is the primary constituent of galaxies. We outline the observed properties of this material, enumerating some candidates covering 90 orders of magnitude in mass. Finally, we argue that the weak scale (100 GeV) is relevant to new physics, including the dark matter problem.

  18. Cold nuclear matter

    Dorso, C O; Nichols, J I; López, J A


    We study the behavior of cold nuclear matter near saturation density (\\rho 0) and very low temperature using classical molecular dynamics. We used three different (classical) nuclear interaction models that yield `medium' or `stiff' compressibilities. For high densities and for every model the ground state is a classical crystalline solid, but each one with a different structure. At subsaturation densities, we found that for every model the transition from uniform (crystal) to non-uniform matter occurs at \\rho ~ 0.12 fm^(-3) = 0.75 \\rho 0. Surprisingly, at the non-uniform phase, the three models produce `pasta-like' structures as those allegedly present in neutron star matter but without the long-range Coulomb interaction and with different length scales.

  19. Dark Matter: Introduction

    Rees, Martin J


    This short review was prepared as an introduction to the Royal Society's 'Dark Matter' conference. It addresses the embarrassing fact that 95% of the universe is unaccounted for. Favoured dark matter candidates are axions or weakly-interacting particles that have survived from the very early universe, but more exotic options cannot be excluded. Experimental searches are being made for the 'dark' particles but we have indirect clues to their nature too. Comparisons of data (from, eg, gravitational lensing) with numerical simulations of galaxy formation can constrain (eg) the particle velocities and collision cross sections. The mean cosmic density of dark matter (plus baryons) is now pinned down to be only about 30% of the critical density However, other recent evidence -- microwave background anisotropies, complemented by data on distant supernovae -- reveals that our universe actually is 'flat', and that its dominant ingredient (about 70% of the total mass-energy) is something quite unexpected -- 'dark energ...

  20. Dark matter detection

    Baudis, Laura


    More than 80 years after its first postulation in modern form, the existence and distribution of dark matter in our Universe is well established. Dark matter is the gravitational glue that holds together galaxies, galaxy clusters and structures on the largest cosmological scales, and an essential component to explain the observed fluctuations in the cosmic microwave background. Yet its existence is inferred indirectly, through its gravitational influence on luminous matter, and its nature is not known. A viable hypothesis is that dark matter is made of new, elementary particles, with allowed masses and interaction strengths spanning a wide range. Two well-motivated classes of candidates are axions and weakly interacting massive particles (WIMPs), and experimental efforts have now reached sensitivities that allow them to test this hypothesis. Axions, produced non-thermally in the early Universe, can be detected by exploiting their predicted couplings to photons and electrons. WIMPs can be detected directly by looking for their collisions with atomic nuclei ultra-low background detectors, or indirectly, through the observation of their annihilation products such as neutrinos, gamma rays, positrons and antiprotons over the astrophysical background. A complementary method is the production of dark matter particles at colliders such as the Large Hadron Collider, where they could be observed indirectly via missing transverse energy, or via associated particle production. I will review the main experimental efforts to search for dark matter particles, and the existing constraints on the interaction cross sections. I will also discuss future experiments, their complementarity and their ability to measure the properties of these particles.

  1. Making organization research matter

    Flyvbjerg, Bent


    research or any of the social sciences. Second, we must address problems that matter to groups in the local, national, and global communities in which we live, and we must do it in ways that matter; we must focus on issues of context, values, and power, as advocated by great social scientists from...... Aristotle and Machiavelli to Max Weber and Pierre Bourdieu. Finally, we must effectively and dialogically communicate the results of our research to our fellow citizens and carefully listen to their feedback. If we do this – focus on specific values and interests in the context of particular power relations...

  2. Condensed matter physics

    Isihara, A


    More than a graduate text and advanced research guide on condensed matter physics, this volume is useful to plasma physicists and polymer chemists, and their students. It emphasizes applications of statistical mechanics to a variety of systems in condensed matter physics rather than theoretical derivations of the principles of statistical mechanics and techniques. Isihara addresses a dozen different subjects in separate chapters, each designed to be directly accessible and used independently of previous chapters. Topics include simple liquids, electron systems and correlations, two-dimensional

  3. Dark Matter and MOOCs

    Salucci, Paolo


    To teach the topic of Dark Matter in Galaxies to undergraduate and PhD students is not easy, one reason being that the scientific community has not converged yet to a generally shared knowledge. We argue that the teaching of this topic and its subsequent scientific progress may benefit by Massive Online and Open Courses. The reader of this paper can express his/her opinion on this by means of a confidence vote at:

  4. Microstructure of Matter (Rev.)

    Swartz, Cifford E. [State University of New York


    Matter is made up of atoms: the atomic nucleus, protons and neutrons, and electrons. There are several other particles besides protons, neutrons, and electrons, and it has become customary to refer to these as elementary or fundamental particles. The particles make up the fine structure of matter with which this booklet deals. This field of science is often referred to as particle physics or high-energy physics because of the fact that particle beams of extremely high energy are needed in most of its pertinent experiments.

  5. Influence of floral assemblage, facies and diagenesis on petrography and organic geochemistry of the Eocene Bourgas coal and the Miocene Maritza-East lignite (Bulgaria)

    Bechtel, A.; Sachsenhofer, R.F.; Zdravkov, A.; Kostova, I.; Gratzer, R. [University of Leoben, Leoben (Austria)


    Numerous differences in the petrography and organic geochemistry of two Tertiary, low rank coal deposits of Bulgaria, formed within comparable depositional environments, are outlined. Different floral assemblages are indicated as the main sources of organic matter. For the Eocene Bourgas sub-bituminous coals a warm climate plant community dominated by angiosperms is reflected in the biomarker composition, whereas a coniferous flora was the main source of the resinous organic matter of the Miocene Maritza-East lignite. The results are in agreement with palaeobotanical data. These differences in the peat forming vegetation of the Paleogene compared to the Neogene of Bulgaria are attributed to decreasing temperature during the Tertiary.

  6. Tunguska Dark Matter Ball

    Froggatt, C D


    It is suggested that the Tunguska event in June 1908 cm-large was due to a cm-large ball of a condensate of bound states of 6 top and 6 anti-top quarks containing highly compressed ordinary matter. Such balls are supposed to make up the dark matter as we earlier proposed. The expected rate of impact of this kind of dark matter ball with the earth seems to crudely match a time scale of 200 years between the impacts. The main explosion of the Tunguska event is explained in our picture as material coming out from deep within the earth, where it has been heated and compressed by the ball penetrating to a depth of several thousand km. Thus the effect has some similarity with volcanic activity as suggested by Kundt. We discuss the possible identification of kimberlite pipes with earlier Tunguska-like events. A discussion of how the dark matter balls may have formed in the early universe is also given.

  7. Cancer Epidemiology Matters Blog

    The Cancer Epidemiology Matters blog helps foster a dialogue between the National Cancer Institute's (NCI) Epidemiology and Genomics Research Program (EGRP), extramural researchers, and other individuals, such as clinicians, community partners, and advocates, who are interested in cancer epidemiology and genomics.

  8. Dichromatic Dark Matter

    Bai, Yang; Zhao, Yue


    Both the robust INTEGRAL 511 keV gamma-ray line and the recent tentative hint of the 135 GeV gamma-ray line from Fermi-LAT have similar signal morphologies, and may be produced from the same dark matter annihilation. Motivated by this observation, we construct a dark matter model to explain both signals and to accommodate the two required annihilation cross sections that are different by more than six orders of magnitude. In our model, to generate the low-energy positrons for INTEGRAL, dark matter particles annihilate into a complex scalar that couples to photon via a charge-radius operator. The complex scalar contains an excited state decaying into the ground state plus an off-shell photon to generate a pair of positron and electron. Two charged particles with non-degenerate masses are necessary for generating this charge-radius operator. One charged particle is predicted to be long-lived and have a mass around 3.8 TeV to explain the dark matter thermal relic abundance from its late decay. The other charged ...

  9. Dichromatic dark matter

    Bai, Yang; Su, Meng; Zhao, Yue


    Both the robust INTEGRAL 511 keV gamma-ray line and the recent tentative hint of the 135 GeV gamma-ray line from Fermi-LAT have similar signal morphologies, and may be produced from the same dark matter annihilation. Motivated by this observation, we construct a dark matter model to explain both signals and to accommodate the two required annihilation cross sections that are different by more than six orders of magnitude. In our model, to generate the low-energy positrons for INTEGRAL, dark matter particles annihilate into a complex scalar that couples to photon via a charge-radius operator. The complex scalar contains an excited state decaying into the ground state plus an off-shell photon to generate a pair of positron and electron. Two charged particles with non-degenerate masses are necessary for generating this charge-radius operator. One charged particle is predicted to be long-lived and have a mass around 3.8 TeV to explain the dark matter thermal relic abundance from its late decay. The other charged particle is predicted to have a mass below 1 TeV given the ratio of the two signal cross sections. The 14 TeV LHC will concretely test the main parameter space of this lighter charged particle.

  10. Exotic nuclear matter

    Lenske H.


    Full Text Available Recent developments of nuclear structure theory for exotic nuclei are addressed. The inclusion of hyperons and nucleon resonances is discussed. Nuclear multipole response functions, hyperon interactions in infinite matter and in neutron stars and theoretical aspects of excitations of nucleon resonances in nuclei are discussed.

  11. Particulate Matter (PM) Pollution

    ... affect the heart and lungs and cause serious health effects. December 1, 2016 - EPA proposes air quality determinations for eleven areas designated "nonattainment" for the 24-hour fine particle standards. Particulate Matter (PM) Pollution PM Basics What is PM, and how does ...

  12. The Universal Dark Matter

    Soberman, R K; Soberman, Robert K.; Dubin, Maurice


    Fragile volatile aggregates with extremely low albedo, gravitationally drawn into the solar system are likely from the dark matter dominating the universal mass. Characteristics of this meteoric population permitted avoiding detection through a half-century's search. Measurements from space probes and in the upper atmosphere prove their existence and confirm their elusive properties.

  13. Template Composite Dark Matter

    Drach, Vincent; Hietanen, Ari; Pica, Claudio


    We present a non perturbative study of SU(2) gauge theory with two fundamental Dirac flavours. We discuss how the model can be used as a template for composite Dark Matter (DM). We estimate one particular interaction of the DM candidate with the Standard Model : the interaction through photon...

  14. Condensed Matter Physics

    Marder, Michael P.


    A modern, unified treatment of condensed matter physics This new work presents for the first time in decades a sweeping review of the whole field of condensed matter physics. It consolidates new and classic topics from disparate sources, teaching "not only about the effective masses of electrons in semiconductor crystals and band theory, but also about quasicrystals, dynamics of phase separation, why rubber is more floppy than steel, electron interference in nanometer-sized channels, and the quantum Hall effect." Six major areas are covered---atomic structure, electronic structure, mechanical properties, electron transport, optical properties, and magnetism. But rather than defining the field in terms of particular materials, the author focuses on the way condensed matter physicists approach physical problems, combining phenomenology and microscopic arguments with information from experiments. For graduate students and professionals, researchers and engineers, applied mathematicians and materials scientists, Condensed Matter Physics provides: * An exciting collection of new topics from the past two decades. * A thorough treatment of classic topics, including band theory, transport theory, and semiconductor physics. * Over 300 figures, incorporating many images from experiments. * Frequent comparison of theory and experiment, both when they agree and when problems are still unsolved. * More than 50 tables of data and a detailed index. * Ample end-of-chapter problems, including computational exercises. * Over 1000 references, both recent and historically significant.

  15. The Birth of Matter


    To mark the World Year of Physics, the Physics Section of the University of Geneva is organising a series of lectures for the uninitiated. Each lecture will begin with a demonstration in the auditorium of the detection of cosmic rays and, in collaboration with Professor E. Ellberger of the Conservatoire de Musique de Genève, of how these signals from the farthest reaches of the Universe can be used to create 'cosmic music'. The fourth lecture in the series, entitled 'The Birth of Matter', will take place on Tuesday 3 May 2005 and will be given by CERN's theoretical physicist, John Ellis. Where does matter come from? Where do the structures that surround us, such as galaxies, come from? Are we living in a world of invisible matter? Why is the universe so old and so big? John Ellis will show how elementary particle physics and, in particular, the LHC under construction at CERN, can answer these questions. The Birth of Matter Professor John Ellis Tuesday 3 May, starting 8.00 p.m. Main Auditorium...

  16. The Birth of Matter


    To mark the World Year of Physics, the Physics Section of the University of Geneva is organising a series of lectures for the uninitiated. Each lecture will begin with a demonstration in the auditorium of the detection of cosmic rays and, in collaboration with Professor E. Ellberger of the Conservatoire de Musique de Genève, of how these signals from the farthest reaches of the Universe can be used to create "cosmic music". The fourth lecture in the series, entitled "The Birth of Matter", will take place on Tuesday 3 May 2005 and will be given by CERN's theoretical physicist, John Ellis. Where does matter come from? Where do the structures that surround us, such as galaxies, come from? Are we living in a world of invisible matter? Why is the universe so old and so big? John Ellis will show how elementary particle physics and, in particular, the LHC under construction at CERN, can answer these questions. The Birth of Matter Professor John Ellis Tuesday 3 May, starting 8.00 p.m. Main Audito...

  17. Template Composite Dark Matter

    Drach, Vincent; Hietanen, Ari; Pica, Claudio


    We present a non perturbative study of SU(2) gauge theory with two fundamental Dirac flavours. We discuss how the model can be used as a template for composite Dark Matter (DM). We estimate one particular interaction of the DM candidate with the Standard Model : the interaction through photon...

  18. The Dark Matter Problem

    Sanders, Robert H.


    1. Introduction; 2. Early history of the dark matter hypothesis; 3. The stability of disk galaxies: the dark halo solutions; 4. Direct evidence: extended rotation curves of spiral galaxies; 5. The maximum disk: light traces mass; 6. Cosmology and the birth of astroparticle physics; 7. Clusters revis

  19. Soft condensed matter

    Frenkel, D.


    These lectures illustrate some of the concepts of soft-condensed matter physics, taking examples from colloid physics. Many of the theoretical concepts will be illustrated with the results of computer simulations. After a brief introduction describing interactions between colloids, the paper focuses

  20. Matter: the fundamental particles

    Landua, Rolf


    "The largest particle physics centre in the world is located in Europe. It straddles the Franco-Swiss border, near Geneva. At CERN - the European Organisation for Nuclear Research , which is focused on the science of nuclear matter rather than on the exploitation of atomic energy - there are over 6 500 scientists." (1 page)

  1. Exceptional composite dark matter

    Ballesteros, Guillermo; Carmona, Adrián; Chala, Mikael


    We study the dark matter phenomenology of non-minimal composite Higgs models with SO(7) broken to the exceptional group G_2. In addition to the Higgs, three pseudo-Nambu-Goldstone bosons arise, one of which is electrically neutral. A parity symmetry is enough to ensure this resonance is stable. In fact, if the breaking of the Goldstone symmetry is driven by the fermion sector, this Z_2 symmetry is automatically unbroken in the electroweak phase. In this case, the relic density, as well as the expected indirect, direct and collider signals are then uniquely determined by the value of the compositeness scale, f. Current experimental bounds allow one to account for a large fraction of the dark matter of the Universe if the dark matter particle is part of an electroweak triplet. The totality of the relic abundance can be accommodated if instead this particle is a composite singlet. In both cases, the scale f and the dark matter mass are of the order of a few TeV.

  2. The Dark Matter Problem

    Sanders, Robert H.

    1. Introduction; 2. Early history of the dark matter hypothesis; 3. The stability of disk galaxies: the dark halo solutions; 4. Direct evidence: extended rotation curves of spiral galaxies; 5. The maximum disk: light traces mass; 6. Cosmology and the birth of astroparticle physics; 7. Clusters

  3. Chromatin as active matter

    Agrawal, Ankit; Ganai, Nirmalendu; Sengupta, Surajit; Menon, Gautam I.


    Active matter models describe a number of biophysical phenomena at the cell and tissue scale. Such models explore the macroscopic consequences of driving specific soft condensed matter systems of biological relevance out of equilibrium through ‘active’ processes. Here, we describe how active matter models can be used to study the large-scale properties of chromosomes contained within the nuclei of human cells in interphase. We show that polymer models for chromosomes that incorporate inhomogeneous activity reproduce many general, yet little understood, features of large-scale nuclear architecture. These include: (i) the spatial separation of gene-rich, low-density euchromatin, predominantly found towards the centre of the nucleus, vis a vis. gene-poor, denser heterochromatin, typically enriched in proximity to the nuclear periphery, (ii) the differential positioning of individual gene-rich and gene-poor chromosomes, (iii) the formation of chromosome territories, as well as (iv), the weak size-dependence of the positions of individual chromosome centres-of-mass relative to the nuclear centre that is seen in some cell types. Such structuring is induced purely by the combination of activity and confinement and is absent in thermal equilibrium. We systematically explore active matter models for chromosomes, discussing how our model can be generalized to study variations in chromosome positioning across different cell types. The approach and model we outline here represent a preliminary attempt towards a quantitative, first-principles description of the large-scale architecture of the cell nucleus.

  4. Asymmetric condensed dark matter

    Aguirre, Anthony


    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate can be very light, $10^{-22}\\,{\\rm eV} \\lesssim m \\lesssim 10^2\\,{\\rm eV}$; the lower limit arises from constraints on small-scale structure formation, while the upper bound ensures that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of deco...

  5. Hot nuclear matter

    Chapman, S.


    The goal in this thesis is thus twofold: The first is to investigate the feasibility of using heavy ion collisions to create conditions in the laboratory which are ripe for the formation of a quark-gluon plasma. The second is to develop a technique for studying some of the many non-perturbative features of this novel phase of matter.

  6. Dark Matter Searches

    Baudis, L


    More than 90% of matter in the Universe could be composed of heavy particles, which were non-relativistic, or 'cold', when they froze-out from the primordial soup. I will review current searches for these hypothetical particles, both via interactions with nuclei in deep underground detectors, and via the observation of their annihilation products in the Sun, galactic halo and galactic center.

  7. Energy Matters - Spring 2002



    Quarterly newsletter from DOE's Industrial Technologies Program to promote the use of energy-efficient industrial systems. The focus of the Spring 2002 Issue of Energy Matters focuses on premium energy efficiency systems, with articles on new gas technologies, steam efficiency, the Augusta Newsprint Showcase, and more.

  8. A triangle that matters

    Gershon, Tim


    "Physicists at "B-factories" in the US and Japan are closing in on an abstract diagram called the unitarity triangle in the quest to explain the difference between matter and antimatter. But such measurements could also point the way to the discovery of new fundamental particles." (5 pages)

  9. Elliott on Mind Matters.

    Maattanen, Pentti


    Argues that David Elliott's conception of the human mind presented in his book "Music Matters" is not coherent. Outlines three alternatives to Elliott's theory of mind. Suggests that the principles associated with the pragmatism of Charles Sanders Pierce would complement Elliott's ideas in his book. (CMK)

  10. Matter in transition

    Anderson, Lara B; Raghuram, Nikhil; Taylor, Washington


    We explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, where a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU(N) require Weierstrass models...

  11. Inflatable Dark Matter

    Davoudiasl, Hooman; McDermott, Samuel D


    We describe a general scenario, dubbed "Inflatable Dark Matter", in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early universe. The overproduction of dark matter that is predicted within many otherwise well-motivated models of new physics can be elegantly remedied within this context, without the need to tune underlying parameters or to appeal to anthropic considerations. Thermal relics that would otherwise be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the non-thermal abundance of GUT or Planck scale axions can be brought to acceptable levels, without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ~ MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the...

  12. Expiration Dates Matter

    Full Text Available ... Updates Expiration Dates Matter Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Get Consumer Updates by E-mail | ... Updates RSS Feed If your medicine has expired, it may not provide the treatment you need. In ...

  13. White matter lesion progression

    Hofer, Edith; Cavalieri, Margherita; Bis, Joshua C;


    BACKGROUND AND PURPOSE: White matter lesion (WML) progression on magnetic resonance imaging is related to cognitive decline and stroke, but its determinants besides baseline WML burden are largely unknown. Here, we estimated heritability of WML progression, and sought common genetic variants...

  14. Soft Matter Characterization

    Borsali, Redouane


    Progress in basic soft matter research is driven largely by the experimental techniques available. Much of the work is concerned with understanding them at the microscopic level, especially at the nanometer length scales that give soft matter studies a wide overlap with nanotechnology. This 2 volume reference work, split into 4 parts, presents detailed discussions of many of the major techniques commonly used as well as some of those in current development for studying and manipulating soft matter. The articles are intended to be accessible to the interdisciplinary audience (at the graduate student level and above) that is or will be engaged in soft matter studies or those in other disciplines who wish to view some of the research methods in this fascinating field. Part 1 contains articles with a largely (but, in most cases, not exclusively) theoretical content and/or that cover material relevant to more than one of the techniques covered in subsequent volumes. It includes an introductory chapter on some of t...

  15. Isotopic compositions of carbonates and organic carbon from upper Proterozoic successions in Namibia: stratigraphic variation and the effects of diagenesis and metamorphism.

    Kaufman, A J; Hayes, J M; Knoll, A H; Germs, G J


    The carbon isotope geochemistry of carbonates and organic carbon in the late Proterozoic Damara Supergroup of Namibia, including the Nama, Witvlei, and Gariep groups on the Kalahari Craton and the Mulden and Otavi groups on the Congo Craton, has been investigated as an extension of previous studies of secular variations in the isotopic composition of late Proterozoic seawater. Subsamples of microspar and dolomicrospar were determined, through petrographic and cathodoluminescence examination, to represent the "least-altered" portions of the rock. Carbon-isotopic abundances in these phases are nearly equal to those in total carbonate, suggesting that 13C abundances of late Proterozoic fine-grained carbonates have not been significantly altered by meteoric diagenesis, although 18O abundances often differ significantly. Reduced and variable carbon-isotopic differences between carbonates and organic carbon in these sediments indicate that isotopic compositions of organic carbon have been altered significantly by thermal and deformational processes, likely associated with the Pan-African Orogeny. Distinctive stratigraphic patterns of secular variation, similar to those noted in other, widely separated late Proterozoic basins, are found in carbon-isotopic compositions of carbonates from the Nama and Otavi groups. For example, in Nama Group carbonates delta 13C values rise dramatically from -4 to +5% within a short stratigraphic interval. This excursion suggests correlation with similar excursions noted in Ediacaran-aged successions of Siberia, India, and China. Enrichment of 13C (delta 13C> +5%) in Otavi Group carbonates reflects those in Upper Riphean successions of the Akademikerbreen Group, Svalbard, its correlatives in East Greenland, and the Shaler Group, northwest Canada. The widespread distribution of successions with comparable isotopic signatures supports hypotheses that variations in delta 13C reflect global changes in the isotopic composition of late

  16. Outcrop analogue study of Permocarboniferous geothermal sandstone reservoir formations (northern Upper Rhine Graben, Germany): impact of mineral content, depositional environment and diagenesis on petrophysical properties

    Aretz, Achim; Bär, Kristian; Götz, Annette E.; Sass, Ingo


    oil and acidic waters led to the dissolution of haematite cements in the lower Permocarboniferous formations. During the Eocene, subsidence of the Upper Rhine Graben porosities and permeabilities of the sandstones of these formations were strongly reduced to 2.5 % and 3.2 × 10-18 m2. The second important influence on reservoir quality is the distinct depositional environment and its influence on early diagenetic processes. In early stage diagenesis, the best influence on reservoir properties exhibits a haematite cementation. It typically occurs in eolian sandstones of the Kreuznach Formation (Upper Permocarboniferous) and is characterized by grain covering haematite coatings, which are interpreted to inhibit cementation, compaction and illitization of pore space during burial. Eolian sandstones taken from outcrops and reservoir depths exhibit the highest porosities (16.4; 12.3 %) and permeabilities (2.0 × 10-15; 8.4 × 10-16 m2). A third important influence on reservoir quality is the general mineral composition and the quartz content which is the highest in the Kreuznach Formation with 73.8 %. Based on the integrated study of depositional environments and diagenetic processes, reservoir properties of the different Permocarboniferous formations within the northern Upper Rhine Graben and their changes with burial depth can be predicted with satisfactory accuracy. This leads to a better understanding of the reservoir quality and enables an appropriate well design for exploration and exploitation of these geothermal resources.

  17. Effects of complexation between organic matter (OM) and clay mineral on OM pyrolysis

    Bu, Hongling; Yuan, Peng; Liu, Hongmei; Liu, Dong; Liu, Jinzhong; He, Hongping; Zhou, Junming; Song, Hongzhe; Li, Zhaohui


    The stability and persistence of organic matter (OM) in source rocks are of great significance for hydrocarbon generation and the global carbon cycle. Clay-OM associations commonly occur in sedimentation and diagenesis processes and can influence the pyrolytic behaviors of OM. In this study, clay-OM complexes, i.e., interlayer clay-OM complexes and clay-OM mixture, were prepared and exposed to high-pressure pyrolysis conditions in confined gold capsule reactors to assess variations in OM pyrolysis products in the presence of clay minerals. Three model organic compounds, octadecanoic acid (OA), octadecy trimethyl ammonium bromide (OTAB), and octadecylamine (ODA), were employed and montmorillonite (Mt) was selected as the representative clay mineral. The solid acidity of Mt plays a key role in affecting the amount and composition of the pyrolysis gases generated by the clay-OM complexes. The Brønsted acid sites significantly promote the cracking of hydrocarbons through a carbocation mechanism and the isomerization of normal hydrocarbons. The Lewis acid sites are primarily involved in the decarboxylation reaction during pyrolysis and are responsible for CO2 generation. Mt exhibits either a catalysis effect or pyrolysis-inhibiting during pyrolysis of a given OM depending on the nature of the model organic compound and the nature of the clay-OM complexation. The amounts of C1-5 hydrocarbons and CO2 that are released from the Mt-OA and Mt-ODA complexes were higher than those of the parent OA and ODA, respectively, indicating a catalysis effect of Mt. In contrast, the amount of C1-5 hydrocarbons produced from the pyrolysis of Mt-OTAB complexes was lower than that of OTAB, which we attribute to an inhibiting effect of Mt. This pyrolysis-inhibiting effect works through the Hoffmann elimination that is promoted by the catalysis of the Brønsted acid sites of Mt, therefore releasing smaller amounts of gas hydrocarbons than the nucleophilic reaction that is induced by the

  18. Transmission of neutrinos through matter

    L Wolfenstein


    Neutrinos travel through matter with negligible absorption except in very extreme situations. However, the index of refraction of neutrinos can play an important role in the oscillation of one type of neutrino to another when passing through matter.

  19. First account on the sedimentological, geochemical and petrophysical record of the Messinian Salinity Crisis in the subsurface of onshore Nile Delta, Egypt.

    Leila, Mahmoud; Moscariello, Andrea


    The giant Cenozoic Nile Delta system in the extreme northern part of Egypt occupies the southeastern part of the Eastern Mediterranean Basin and represents the most prolific gas province in Egypt with estimates more than 62 tcf of proven reserves (Niazi and Dahi, 2004). Despite the importance of the Messinian sediments in the Nile Delta hosting excellent petroleum reservoirs and seals (Dolson et al., 2001), they are still poorly studied. A multidisciplinary sedimentological, geochemical and petrophysical study is being carried out to unravel the depositional environment and tectonic setting before, during and after the important Messinian Salinity Crisis (MSC) period in the Eastern Mediterranean, and how this affected the eastern part of the onshore Nile Delta. The Lower Messinian Qawasim Formation consists of high to low-density turbiditic sandstones displaying several vertical stacked patterns of coarsening and fining upwards trends reflecting different pulses of sedimentation suggesting a sedimentation in a submarine fan developed at the base of shelf slope. The deeply incised valley infill, dating the Upper Messinian consists of the Abu Madi Formation made of lowstand braided and meandering fluvial sandstone interbedded with fine-grained floodplain sandstones and siltstones. The base of this unit is erosional and contains large mud clasts embedded in a fine-grained matrix. The Upper Miocene lowstand fluvial sandstones are capped by estuarine fine-grained cross laminated sandstones, siltstones/mudstones followed by an open marine mudstones of the Early Pliocene Kafr El-Sheikh Formation representing the end of the MSC and the subsequent transgression episode after the re-establishment of the connection between the Mediterranean and the Atlantic Ocean. Both the Qawasim and Abu Madi Formations display similar geochemical fingerprints from the clastic components. Recycled Cretaceous and Eocene sedimentary and granodioritic to intermediate igneous rocks located in

  20. Sedimentological and sequence stratigraphic analysis of Carboniferous deposits in western Libya: Recording the sedimentary response of the northern Gondwana margin to climate and sea-level changes

    Fröhlich, Sebastian; Petitpierre, Laurent; Redfern, Jonathan; Grech, Paul; Bodin, Stéphane; Lang, Simon


    Detailed sedimentological and sequence stratigraphic analysis of Carboniferous (Tournaisian to Moscovian) strata exposed in the north-western Murzuq Basin and southern Ghadames Basin, western Libya, provides new insights into the sedimentary response of the northern Gondwana margin to climate and sea-level change. The Lower Carboniferous Marar and Assedjefar Formations can be divided into five depositional sequences of 3rd order. In total 27 facies types are defined, grouped into four facies associations: offshore shales, shallow marine clastics, fluvial sandstones and marine carbonates. The bulk of the Lower Carboniferous interval is dominated by an alternation of offshore shales and shallow marine clastics, which were deposited during the transgressive and highstand systems tracts. The clastic deposits mostly consist of laterally persistent coarsening and thickening upward cycles with a common succession from basal hummocky cross-stratified sandstones to ripple-laminated sandstones, capped by multidirectional cross-stratified sandstones. Within the lowstand systems tracts, lenticular sandbodies have been identified, which vary in thickness from 1.5 m (ca. 40 m wide) to 50 m (ca. 1.5 km wide). These are interpreted to be fluvial channel complexes based on their geometry, erosive base, and presence of thick stacked sandstones with unidirectional planar and trough cross-bedding, the absence of bioturbation and occurrence of land plant fragments. These channel complexes mostly cut down into offshore shales, and are interpreted to be bound at the base by sequence boundaries. Palaeogeographic maps generated for each lowstand system show the location and palaeoflow direction of these fluvial channel complexes. They are interpreted to represent large incised valleys filled with thick fluvial sandstones. Their identification and distribution indicates repeated exposure of large areas of western Libya, most-likely controlled by major eustatic sea-level changes. The

  1. Origin of shallow submarine mass movements and their glide planes—Sedimentological and geotechnical analyses from the continental slope off northern Norway

    Baeten, Nicole J.; Laberg, Jan Sverre; Vanneste, Maarten; Forsberg, Carl Fredrik; Kvalstad, Tore J.; Forwick, Matthias; Vorren, Tore O.; Haflidason, Haflidi


    Submarine landslides are often characterized by a basal surface of rupture parallel to the stratigraphy, in which downslope movement is initiated. However, little is known about the sedimentology and physical properties of the sediments within these surfaces. In this study, we present a multiproxy analysis of the sediments collected from a giant piston core penetrating a shallow submarine mass transport deposit, in combination with high-resolution seismoacoustic data to identify and characterize the basal glide plane and the weaker sediments in which movement was initiated. The initial phase of instability consists of a single fracture that formed due to the downslope movement of a mostly intact slab of sediments. The 16 m long core, comprising mostly undisturbed massive and laminated ice-rafted debris-rich clay penetrated this slab. The base of the slab is characterized by a high-amplitude semicontinuous reflection visible on the subbottom profiler data at about 12.5 m depth, interpreted to originate from the glide plane on top of a plumite deposit. This plumite has dilative behavior with pore pressure decrease with increasing shear strain and high undrained shear strength. Movement probably started within contouritic sediments immediately above the glide plane, characterized by higher sensitivities and higher water contents. The occurrence of the mass movements documented in this study are likely affected by the presence of a submarine landslide complex directly downslope. The slide scar of this landslide complex promoted retrogressive movement farther upslope and progressive spreading of strain softening along the slide base and in the slide mass. Numerical models (infinite slope, BING, and retrogressive slope models) illustrate that the present-day continental slope is essentially stable and allow reconstruction of the failure processes when initiated by an external trigger.

  2. Sedimentologic and paleoclimatic reconstructions of carbonate factory evolution in the Alborz Basin (northern Iran) indicate a global response to Early Carboniferous (Tournaisian) glaciations

    Sardar Abadi, Mehrdad; Kulagina, Elena I.; Voeten, Dennis F. A. E.; Boulvain, Frédéric; Da Silva, Anne-Christine


    The Lower Carboniferous Mobarak Formation records the development of a storm-sensitive pervasive carbonate factory on the southern Paleo-Tethyan passive margin following the opening of the Paleo-Tethys Ocean into the Alborz Basin along the northern margin of Gondwana. Its depositional facies encompass inner ramp peritidal environments, peloidal to crinoidal shoals, storm to fair-weather influenced mid-ramps, proximal to distal shell beds and low energy outer ramps. Sedimentological analyses and foraminiferal biostratigraphy reveal four events affecting carbonate platform evolution in the Alborz Basin during the Lower Carboniferous: (1) A transgression following global temperature rise in the Early Tournaisian (middle Hastarian) caused the formation of thick-bedded argillaceous limestones. This interval correlates with Early Tournaisian nodular to argillaceous limestones in the Moravia Basin (Lisen Formation, Czech Republic), the Dinant Basin (Pont d'Arcole Formation, Belgium), and at the Rhenish Slate Mountains (Lower Alum shale, Germany). (2) Late Hastarian-early Ivorian glaciations previously identified in Southern Gondwana but had not yet recognized in Northern Gondwana were recorded through a sequence boundary. (3) During the Late Tournaisian-Early Visean?, a differential block faulting regime along the basin's margin caused uplift of the westernmost parts of the Alborz Basin and resulted in subsidence in the eastern part of the central basin. This tectonically controlled shift in depositional regime caused vast sub-aerial exposure and brecciation preserved in the top of the Mobarak Formation in the western portion of the Central Alborz Basin. (4) Tectonic activity coinciding with a progressive, multiphase sea level drop caused indirectly by the Viséan and Serpukhovian glaciations phases ultimately led to the stagnation of the carbonate factory. Paleothermometry proxies, the presence of foraminiferal taxa with a northern Paleo-Tethyan affinity and evidence for

  3. Sedimentology of Hirnantian glaciomarine deposits in the Balkan Terrane, western Bulgaria: Fixing a piece of the north peri-Gondwana jigsaw puzzle

    Chatalov, Athanas


    Glaciomarine deposits of late Hirnantian age in the western part of the Palaeozoic Balkan Terrane have persistent thickness ( 7 m) and lateral uniformity in rock colour, bedding pattern, lithology, and sedimentary structures. Four lithofacies are distinguished from base to top: lonestone-bearing diamictites, interbedded structureless mudstones, crudely laminated diamictites, and finely laminated mudstones. The diamictites are clast-poor to clast-rich comprising muddy to sandy varieties. Their compositional maturity is evidenced by the very high amount of detrital quartz compared to the paucity of feldspar and unstable lithic grains. Other textural components include extraclasts derived from the local Ordovician basement, mudstone intraclasts, and sediment aggregates. Turbate structures, grain lineations, and soft sediment deformation of the matrix below larger grains are locally observed. Sedimentological analysis reveals that deposition occurred in an ice-intermediate to ice-distal, poorly agitated shelf environment by material supplied from meltwater buoyant plumes and rain-out from ice-rafted debris. Remobilization by mass-flow processes (cohesive debris flows and slumps) was an important mechanism particularly for the formation of massive diamictites. The glaciomarine deposits represent a typical deglaciation sequence reflecting retreat of the ice front (grounded or floating ice sheet), relative sea-level rise and gradually reduced sedimentation rate with increasing contribution from suspension fallout. This sequence was deposited on the non-glaciated shelf of the intracratonic North Gondwana platform along the southern margin of the Rheic Ocean. The Hirnantian strata of the Balkan Terrane can be correlated with similar glaciomarine deposits known from peri-Gondwana terranes elsewhere in Europe showing clear 'Armorican affinity'. Several lines of evidence suggest that the provenance of siliciclastic material was associated mainly with sedimentary recycling of

  4. Methods and Characteristics of Salt Lake Sedimentology Research%盐湖沉积的研究方法与研究特点

    李建森; 李廷伟; 马海州


    盐湖沉积研究具有自身的特殊性与不可替代性.基于目前国内外盐湖沉积研究的大发展,介绍了盐湖沉积学的发展历史、研究内容、研究方法,综述了近年来盐湖沉积学的理论、方法、应用研究上的进展,指出微观化、精细化、定量化、多指标、多学科交叉、注重应用是盐湖沉积学发展的大趋势,并对此进行了展望.加强基础研究与国际合作,面向重大科学问题,注重实质性学科交叉,是未来盐湖沉积研究的重点.%Salt lake sedimentary study has its own peculiarity and non-substitutability, based on the big development of salt lake deposits research at home and abroad, this paper introduced the development history and the research contents and methods. Points out the fine and quantitative, micro, index, interdisciplinary research is a trend in the development of sedimentation salt lake, and more attention must be paid to the application of it. At the same time, some prospects of salt lake sedimentology research were reviewed , face to the important scientific problems, strengthen basic research and international cooperation, pay attention to the substantive subject crossing is the key of salt lake deposits study.

  5. Structure and temporal variations of a magmatic CO2 degassing site in the Bohemian Massif (Europe): an integrated geophysical-geochemical-sedimentological study

    Flechsig, C.; Nickschick, T.; Kaempf, H. W.; Mrlina, J.; Bussert, R.


    The Bohemian Massif, as a part of the Variscan orogenic belt, is one of the largest stable intracontinental zone of pre-Permian rocks in Central and Western Europe. Its geodynamically most active western part, the West Bohemia/Vogtland region, shows persistent seismic activity of recurring earthquake swarms (up to M 4.5) and intense CO2 degassing at the surface (mofettes) with mantle-derived He-isotope signatures. To understand the fluid migration in the subsurface and its control by tectonics is one research issue which must be addressed to clarify the possible link to the earthquake generation. We present results of an interdisciplinary study of near-surface sediments in a mofette field. The study comprises geophysical (gravimetry and geoelectrics), geochemical (CO2 soil gas and gas flux measurements), and sedimentological investigations. The investigations reveal a positive correlation between areas of high soil gas (CO2) concentration and flux with geophysical anomalies (negative self potential, positive structures of low electrical resistivity, decreased density) as well as with specific sediment properties (content of pyrite and organic material, occurrence of dispersed pebbles, uplifted clay layer). These features are thought to be directly or indirectly related to the magmatic caused fluid flow. Soil gas (CO2) flux and concentration anomalies spread out with a linear trend, suggesting the fault control on gas ascent. Negative self potential anomalies at the degassing spots were interpreted considering as having been caused by a downward movement of the meteoric water balancing the upward CO2 gas flux. The model of the active mofettes has to consider its bonding to deep-seated faults and can be tracked. The results fit into a tectonic model in which the mofette fields are in the centers of two independent pull-apart basin-like structures.

  6. Tachyonic models of dark matter

    Nikitin, Igor


    We consider a spherically symmetric stationary problem in General Relativity, including a black hole, inflow of normal and tachyonic matter and outflow of tachyonic matter. Computations in a weak field limit show that the resulting concentration of matter around the black hole leads to gravitational effects equivalent to those associated with dark matter halo. In particular, the model reproduces asymptotically constant galactic rotation curves, if the tachyonic flows of the central supermassive black hole in the galaxy are considered as a main contribution.

  7. Dark Matter Searches at LHC

    Terashi, Koji; The ATLAS collaboration


    This talk will present dark matter searches at the LHC in the PIC2017 conference. The main emphasis is placed on the direct dark matter searches while the interpretation of searches for SUSY and invisible Higgs signals for the dark matter is also presented.

  8. Dark Matter in the Universe


    Vera Rubin gave an evening lecture during the 19th General Assembly of the International Astronomical Union, in 1985 at New Delhi, on dark matter. It was a lucid introduction to the issues regarding dark matter, as well as a comprehensive review of the evidences for dark matter. This extraordinary lecture, aimed towards non-specialists, is reprinted below.

  9. Is old organic matter simple organic matter?

    Nunan, Naoise; Lerch, Thomas; Pouteau, Valérie; Mora, Philippe; Changey, Fréderique; Kätterer, Thomas; Herrmann, Anke


    Bare fallow soils that have been deprived of fresh carbon inputs for prolonged periods contain mostly old, stable organic carbon. In order to shed light on the nature of this carbon, the functional diversity profiles (MicroResp™, Biolog™ and enzyme activity spectra) of the microbial communities of long-term barefallow soils were analysed and compared with those of the microbial communities from their cultivated counterparts. The study was based on the idea that microbial communities adapt to their environment and that therefore the catabolic and enzymatic profiles would reflect the type of substrates available to the microbial communities. The catabolic profiles suggested that the microbial communities in the long-term bare-fallow soil were exposed to a less diverse range of substrates and that these substrates tended to be of simpler molecular forms. Both the catabolic and enzyme activity profiles suggested that the microbial communities from the long-term bare-fallow soils were less adapted to using polymers. These results do not fit with the traditional view of old, stable carbon being composed of complex, recalcitrant polymers. An energetics analysis of the substrate use of the microbial communities for the different soils suggested that the microbial communities from the long-term bare-fallow soils were better adapted to using readily oxidizable,although energetically less rewarding, substrates. Microbial communities appear to adapt to the deprivation of fresh organic matter by using substrates that require little investment.

  10. Hyperons in dense matter

    Dapo, Haris


    The hyperon-nucleon YN low momentum effective interaction (V{sub low} {sub k}) allows for an extensive study of the behavior of hyperons in dense matter, together with an investigation of effects of the presence of hyperons on dense matter. The first step towards this goal is the construction of the matrix elements for the hyperon-nucleon low momentum potential. In order to assess the different properties of hyperons within these potentials we calculate the hyperon single-particle potentials in the Hartree-Fock approximation for all of the interactions. Their dependence on both momentum and density, is studied. The single-particle potentials are then used to determine the chemical potential of hyperons in neutron stars. For nucleonic properties, the nucleon-nucleon V{sub low} {sub k} can be used with the caveat that the calculation of the ground-state energy of symmetric nuclear matter does not correctly reproduce the properties of matter at saturation. With the nucleon-nucleon V{sub low} {sub k} one is unable to reach the densities needed for the calculation of neutron star masses. To circumvent this problem we use two approaches: in the first one, we parametrize the entire nucleonic sector. In the second one, we replace only the three-body force. The former will enable us to study neutron star masses, and the latter for studying the medium's response to the external probe. In this thesis we take the external probe to be the neutrino. By combining this parametrization with the YN V{sub low} {sub k} potential, we calculate the equation of state of equilibrated matter. Performing the calculation in the Hartree-Fock approximation at zero temperature, the concentrations of all particles are calculated. From these we can ascertain at which densities hyperons appear for a wide range of parameters. Finally, we calculate the masses of neutron stars with these concentrations. For the calculation of the medium's response to an external probe, we replace the three

  11. Light, Matter, and Geometry

    Frisvad, Jeppe Revall


    This thesis is about physically-based modelling of the appearance of materials. When a material is graphically rendered, its appearance is computed by considering the interaction of light and matter at a macroscopic level. In particular, the shape and the macroscopic optical properties...... of the material determine how it will interact with incident illumination. In this thesis the macroscopic optical properties are connected to the microscopic physical theories of light and matter. This enables prediction of the macroscopic optical properties of materials, and, consequently, also prediction...... of appearance based on the contents and the physical conditions of the materials. Physically-based appearance models have many potential input and output parameters. There are many choices that must be made: How many material components to include in the model, how many physical conditions to take into account...

  12. Radiative accidental matter

    Sierra, D Aristizabal; Wegman, D


    Accidental matter models are scenarios where the beyond-the-standard model physics preserves all the standard model accidental and approximate symmetries up to a cutoff scale related with lepton number violation. We study such scenarios assuming that the new physics plays an active role in neutrino mass generation, and show that this unavoidably leads to radiatively induced neutrino masses. We systematically classify all possible models and determine their viability by studying electroweak precision data, big bang nucleosynthesis and electroweak perturbativity, finding that the latter places the most stringent constraints on the mass spectra. These results allow the identification of minimal radiative accidental matter models for which perturbativity is lost at high scales. We calculate radiative charged-lepton flavor violating processes in these setups, and show that $\\mu\\to e \\gamma$ has a rate well within MEG sensitivity provided the lepton-number violating scale is at or below $10^6\\,$ GeV, a value (natur...

  13. The Dark Matter Telescope

    Tyson, J A; Angel, J R P; Wittman, David


    Weak gravitational lensing enables direct reconstruction of dark matter maps over cosmologically significant volumes. This research is currently telescope-limited. The Dark Matter Telescope (DMT) is a proposed 8.4 m telescope with a 3 degree field of view, with an etendue of 260 $(m. degree)^2$, ten times greater than any other current or planned telescope. With its large etendue and dedicated observational mode, the DMT fills a nearly unexplored region of parameter space and enables projects that would take decades on current facilities. The DMT will be able to reach 10-sigma limiting magnitudes of 27-28 magnitude in the wavelength range .3 - 1 um over a 7 square degree field in 3 nights of dark time. Here we review its unique weak lensing cosmology capabilities and the design that enables those capabilities.

  14. Particulate matter dynamics

    Cionco, Rodolfo G; Caligaris, Marta G


    A substantial fraction of the particulate matter released into the atmosphere by industrial or natural processes corresponds to particles whose aerodynamic diameters are greater than 50 mm. It has been shown that, for these particles, the classical description of Gaussian plume diffusion processes, is inadequate to describe the transport and deposition. In this paper we present new results concerning the dispersion of coarse particulate matter. The simulations are done with our own code that uses the Bulirsch Stoer numerical integrator to calculate threedimensional trajectories of particles released into the environment under very general conditions. Turbulent processes are simulated by the Langevin equation and weather conditions are modeled after stable (Monin-Obukhov length L> 0) and unstable conditions (L <0). We present several case studies based on Monte Carlo simulations and discusses the effect of weather on the final deposition of these particles.

  15. Sedimentology and Reservoir Characteristics of Early Cretaceous Fluvio-Deltaic and Lacustrine Deposits, Upper Abu Gabra Formation, Sufyan Sub-basin, Muglad Rift Basin, Sudan

    Yassin, Mohamed; Abdullatif, Osman; Hariri, Mustafa


    Sufyan Sub-basin is an East-West trending Sub-basin located in the northwestern part of the Muglad Basin (Sudan), in the eastern extension of the West and Central Africa Rift System (WCARS). The Early Cretaceous Abu Gabra Formation considered as the main source rock in the Muglad Basin. In Sufyan Sub-basin the Early Cretaceous Upper Abu Gabra Formation is the main oil-producing reservoir. It is dominated by sandstone and shales deposited in fluvio-deltaic and lacustrine environment during the first rift cycle in the basin. Depositional and post-depositional processes highly influenced the reservoir quality and architecture. This study investigates different scales of reservoir heterogeneities from macro to micro scale. Subsurface facies analysis was analyzed based on the description of six conventional cores from two wells. Approaches include well log analysis, thin sections and scanning electron microscope (SEM) investigations, grain-size, and X-ray diffraction (XRD) analysis of the Abu Gabra sandstone. The cores and well logs analyses revealed six lithofacies representing fluvio-deltaic and lacustrine depositional environment. The sandstone is medium to coarse-grained, poorly to moderately sorted and sub-angular to subrounded, Sub-feldspathic arenite to quartz arenite. On macro-scale, reservoir quality varies within Abu Gabra reservoir where it shows progressive coarsening upward tendencies with different degrees of connectivity. The upper part of the reservoir showed well connected and amalgamated sandstone bodies, the middle to lower parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenesis.The XRD and SEM analyses show that kaolinite and chlorite clay are the common clay minerals in the studied samples. Clay matrix and quartz overgrowth have significantly reduced the reservoir porosity and permeability, while the dissolution of feldspars

  16. The role of sedimentology, oceanography, and alteration on the δ56Fe value of the Sokoman Iron Formation, Labrador Trough, Canada

    Raye, Urmidola; Pufahl, Peir K.; Kyser, T. Kurtis; Ricard, Estelle; Hiatt, Eric E.


    The Sokoman Formation is a ca. 100-m-thick succession of interbedded iron formation and fine-grained siliciclastics deposited at 1.88 Ga. Accumulation occurred on a dynamic paleoshelf where oxygen stratification, coastal upwelling of hydrothermally derived Fe and Si, microbial processes, tide and storm currents, diagenesis, and low-grade prehnite-pumpellyite metamorphism controlled lithofacies character and produced complex associations of multigenerational chert, hematite, magnetite, greenalite, stilpnomelane and Fe carbonate. Hematite-rich facies were deposited along suboxic segments of the coastline where photosynthetic oxygen oases impinged on the seafloor. Hematitic, cross-stratified grainstones were formed by winnowing and reworking of freshly precipitated Fe-(oxyhydr)oxide and opal-A by waves and currents into subaqueous dunes. Magnetite-rich facies contain varying proportions of greenalite and stilpnomelane and record deposition in anoxic middle shelf environments beneath an oxygen chemocline. Minor negative Ce anomalies in hematitic facies, but prominent positive Ce and Eu anomalies and high LREE/HREE ratios in magnetite-rich facies imply the existence of a weakly oxygenated surface ocean above anoxic bottom waters. The Fe isotopic composition of 31 whole rock (-0.46 ⩽ δ56Fe ⩽ 0.47‰) and 21 magnetite samples (-0.29 ⩽ δ56Fe ⩽ 0.22‰) from suboxic and anoxic lithofacies was controlled primarily by the physical oceanography of the paleoshelf. Despite low-grade metamorphism recorded by the δ18O values of paragenetically related quartz and magnetite, the Sokoman Formation preserves a robust primary Fe isotopic signal. Coastal upwelling is interpreted to have affected the isotopic equilibria between Fe2+aq and Fe-(oxyhydr)oxide in open marine versus coastal environments, which controlled the Fe isotopic composition of lithofacies. Unlike previous work that focuses on microbial and abiotic fractionation processes with little regard for

  17. Mg fractionation in crustose coralline algae: Geochemical, biological, and sedimentological implications of secular variation in the Mg/Ca ratio of seawater

    Ries, Justin B.


    The Mg/Ca ratio of seawater has varied significantly throughout the Phanerozoic Eon, primarily as a function of the rate of ocean crust production. Specimens of the crustose coralline alga Neogoniolithon sp. were grown in artificial seawaters encompassing the range of Mg/Ca ratios shown to have existed throughout the Phanerozoic. Significantly, the coralline algae's skeletal Mg/Ca ratio varied in lockstep with the Mg/Ca ratio of the artificial seawater. Specimens grown in seawater treatments formulated with identical Mg/Ca ratios but differing absolute concentrations of Mg and Ca exhibited no significant differences in skeletal Mg/Ca ratios, thereby emphasizing the importance of the ambient Mg/Ca ratio, and not the absolute concentration of Mg, in determining the Mg/Ca ratio of coralline algal calcite. Specimens grown in seawater of the lowest molar Mg/Ca ratio ( mMg/Ca = 1.0) actually changed their skeletal mineralogy from high-Mg (skeletal mMg/Ca > 0.04) to low-Mg calcite (skeletal mMg/Ca algae, which exhibit morphologies and modes of calcification comparable to Neogoniolithon sp., would have produced low-Mg calcite from the middle Cambrian to middle Mississippian and during the middle to Late Cretaceous, when oceanic mMg/Ca approached unity. By influencing the original Mg content of carbonate facies in which these algae have been ubiquitous, this condition has significant implications for the geochemistry and diagenesis of algal limestones throughout most of the Phanerozoic. The crustose coralline algae's precipitation of high-Mg calcite from seawater that favors the abiotic precipitation of aragonite indicates that these algae dictate the precipitation of the calcitic polymorph of CaCO 3. However, the algae's nearly abiotic pattern of Mg fractionation in their skeletal calcite suggests that their biomineralogical control is limited to polymorph specification and is generally ineffectual in the regulation of skeletal Mg incorporation. Therefore, the Mg/Ca ratio

  18. Condensed matter physics

    Marder, Michael P


    This Second Edition presents an updated review of the whole field of condensed matter physics. It consolidates new and classic topics from disparate sources, teaching not only about the effective masses of electrons in semiconductor crystals and band theory, but also about quasicrystals, dynamics of phase separation, why rubber is more floppy than steel, granular materials, quantum dots, Berry phases, the quantum Hall effect, and Luttinger liquids.

  19. Matter in general relativity

    Ray, J. R.


    Two theories of matter in general relativity, the fluid theory and the kinetic theory, were studied. Results include: (1) a discussion of various methods of completing the fluid equations; (2) a method of constructing charged general relativistic solutions in kinetic theory; and (3) a proof and discussion of the incompatibility of perfect fluid solutions in anisotropic cosmologies. Interpretations of NASA gravitational experiments using the above mentioned results were started. Two papers were prepared for publications based on this work.

  20. Subquantum level of matter

    Sannikov-Proskuryakov, S S


    Not long ago spinors were considered as the simplest and most fundamental objects of particle physics. However it turns out that there exist more fundamental objects, from which spinors may be built (and, in this sense, they play the role of Kummer ideal numbers). We call they fundors. They are used in the description of a new more deep level of physical reality - pre-matter, from which usual elementary particles arise. Here, a mathematical carcass of the theory is built.