The Completeness of the Fossil Record of Mesozoic Birds: Implications for Early Avian Evolution

Science.gov (United States)

Brocklehurst, Neil; Upchurch, Paul; Mannion, Philip D.; O'Connor, Jingmai

2012-01-01

Many palaeobiological analyses have concluded that modern birds (Neornithes) radiated no earlier than the Maastrichtian, whereas molecular clock studies have argued for a much earlier origination. Here, we assess the quality of the fossil record of Mesozoic avian species, using a recently proposed character completeness metric which calculates the percentage of phylogenetic characters that can be scored for each taxon. Estimates of fossil record quality are plotted against geological time and compared to estimates of species level diversity, sea level, and depositional environment. Geographical controls on the avian fossil record are investigated by comparing the completeness scores of species in different continental regions and latitudinal bins. Avian fossil record quality varies greatly with peaks during the Tithonian-early Berriasian, Aptian, and Coniacian–Santonian, and troughs during the Albian-Turonian and the Maastrichtian. The completeness metric correlates more strongly with a ‘sampling corrected’ residual diversity curve of avian species than with the raw taxic diversity curve, suggesting that the abundance and diversity of birds might influence the probability of high quality specimens being preserved. There is no correlation between avian completeness and sea level, the number of fluviolacustrine localities or a recently constructed character completeness metric of sauropodomorph dinosaurs. Comparisons between the completeness of Mesozoic birds and sauropodomorphs suggest that small delicate vertebrate skeletons are more easily destroyed by taphonomic processes, but more easily preserved whole. Lagerstätten deposits might therefore have a stronger impact on reconstructions of diversity of smaller organisms relative to more robust forms. The relatively poor quality of the avian fossil record in the Late Cretaceous combined with very patchy regional sampling means that it is possible neornithine lineages were present throughout this interval but

Thermochronological constraints on the Cambrian to recent geological evolution of the Argentina passive continental margin

Science.gov (United States)

Kollenz, Sebastian; Glasmacher, Ulrich A.; Rossello, Eduardo A.; Stockli, Daniel F.; Schad, Sabrina; Pereyra, Ricardo E.

2017-10-01

Passive continental margins are geo-archives that store information from the interplay of endogenous and exogenous forces related to continental rifting, post-breakup history, and climate changes. The recent South Atlantic passive continental margins (SAPCMs) in Brazil, Namibia, and South Africa are partly high-elevated margins ( 2000 m a.s.l.), and the recent N-S-trending SAPCM in Argentina and Uruguay is of low elevation. In Argentina, an exception in elevation is arising from the higher topography (> 1000 m a.s.l.) of the two NW-SE-trending mountain ranges Sierras Septentrionales and Sierras Australes. Precambrian metamorphic and intrusive rocks, and siliciclastic rocks of Ordovician to Permian age represent the geological evolution of both areas. The Sierras Australes have been deformed and metamorphosed (incipient - greenschist) during the Gondwanides Orogeny. The low-temperature thermochronological (LTT) data (history of the Gondwanides and the Mesozoic and Cenozoic South Atlantic geological evolution. Upper Carboniferous zircon (U-Th/He)-ages (ZHe) indicate the earliest cooling below 180 °C/1 Ma. Most of the ZHe-ages are of Upper Triassic to Jurassic age. The apatite fission-track ages (AFT) of Sierras Septentrionales and the eastern part of Sierras Australes indicate the South Atlantic rifting and, thereafter. AFT-ages of Middle to Upper Triassic on the western side of the Sierras Australes are in contrast, indicating a Triassic exhumation caused by the eastward thrusting along the Sauce Grande wrench. The corresponding t-T models report a complex subsidence and exhumation history with variable rates since the Ordovician. Based on the LTT-data and the numerical modelling we assume that the NW-SE-trending mountain ranges received their geographic NW-SE orientation during the syn- to post-orogenic history of the Gondwanides.

Geological evolution of clay sediments: the petroleum exploration vision

International Nuclear Information System (INIS)

Schneider, F.

2004-01-01

The radioactive waste isolation capacity assessment for a clay sediment host rock is link: (1) to the understanding of their present state properties and 3-D repartition (from basin evolution, including sedimentary and diagenetic process); and (2) to the prediction of their future evolution during the next million years. For petroleum exploration, basin modelling aims at reconstructing the accumulation of hydrocarbons at basin scale, and at geological timescale, taking into account the effects of kinematics displacements, sedimentation, erosion, compaction, temperatures history, overpressures and fluids flows (water and hydrocarbons). Furthermore, explorationists wish to address overpressure reconstruction in order to estimate the risks of drilling. Clay sediments are of interest for petroleum exploration because source rocks and seal are generally composed of them. Nevertheless, in spite of their occurrence in nature their evolution at geological timescale is not well understood. And, most of the knowledge has been achieved by those working in the realms of soils mechanics and civil engineering until the present geological investigations for long term radioactive waste repositories. Application of this knowledge to clay sediment is considered to be valid within the first hundreds of meters at the top of the sedimentary pile, according to a repository depth. This paper is dedicated to the sedimentary rocks behaviour at geological timescale. This behaviour is characterised by: (1) the deposition of the sediment; (2) the loading path at geological timescale; (3) the constitutive law which includes the consolidation process and the rupture criteria; and (4) the parameters evolution related to consolidation. (author)

Deformation style of the Mesozoic sedimentary rocks in southern Thailand

Science.gov (United States)

Kanjanapayont, Pitsanupong

2014-10-01

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

A bottom-up perspective on ecosystem change in Mesozoic oceans.

Science.gov (United States)

Knoll, Andrew H; Follows, Michael J

2016-10-26

Mesozoic and Early Cenozoic marine animals across multiple phyla record secular trends in morphology, environmental distribution, and inferred behaviour that are parsimoniously explained in terms of increased selection pressure from durophagous predators. Another systemic change in Mesozoic marine ecosystems, less widely appreciated than the first, may help to explain the observed animal record. Fossils, biomarker molecules, and molecular clocks indicate a major shift in phytoplankton composition, as mixotrophic dinoflagellates, coccolithophorids and, later, diatoms radiated across shelves. Models originally developed to probe the ecology and biogeography of modern phytoplankton enable us to evaluate the ecosystem consequences of these phytoplankton radiations. In particular, our models suggest that the radiation of mixotrophic dinoflagellates and the subsequent diversification of marine diatoms would have accelerated the transfer of primary production upward into larger size classes and higher trophic levels. Thus, phytoplankton evolution provides a mechanism capable of facilitating the observed evolutionary shift in Mesozoic marine animals. © 2016 The Authors.

Mesozoic cyclostratigraphy, the 405-kyr orbital eccentricity metronome, and the Astronomical Time Scale (Invited)

Science.gov (United States)

Hinnov, L.; Ogg, J. G.

2009-12-01

Mesozoic cyclostratigraphy from around the world is being assessed to construct a continuous Astronomical Time Scale (ATS) based on Earth’s cyclic orbital parameters. The recognition of a prevalent sedimentary cycling with a ~400-kyr period associated with forcing by the stable 405-kyr orbital eccentricity variation is an important development. Numerous formations spanning 10 to 20 myr (and longer) intervals in the Cretaceous, Jurassic and Triassic clearly express this dominant cycle and provide a robust basis for 405-kyr-scale calibration of the ATS. This 405-kyr metronome will enable extension of the well-defined Cenozoic ATS for scaling of the past quarter-billion years of Earth history. This astronomical calibration has a resolution comparable to the 1% to 0.1% precision for radioisotope dating of Mesozoic ash beds, with the added benefit of providing continuous stratigraphic coverage between dated beds. Extended portions of the Mesozoic ATS have already provided new insights into long-standing geologic problems of seafloor spreading, tectonics, eustasy, and paleoclimate change. Ongoing work is focused on closing gaps in coverage and on collecting duplicate cyclostratigraphic records for the entire Mesozoic Era.

Geodynamic setting of mesozoic magmatism and its relationship to uranium metallogenesis in southeastern China

International Nuclear Information System (INIS)

Chen Peirong

2004-01-01

In the southeastern China, magmatism was developed quite intensely in Mesozoic forming a large quantity of rare and nonferrous metal deposits. The Indosinian orogenic movement ( Early Mesozoic) and the Yanshanian movement (Late Mesozoic) provided the dynamic force for magmatism and metallogenesis in this region. The intra-plate extension was induced by the Indosinian orogenic movement in South China continent under a regionally compressional framework to form Indosinian granites. The Yanshanian movement was a post-orogenic geologic event in relation to the Indosinian orogeny, and characterized by intense lithosphere breaking-up, resulting in large scale magmatic activities and a great amount of mineral resources was formed. The Indosinian granites overprinted by the Yanshanian tectono-magma event were closely related to uranium metallogenesis and were likely a kind of uranium source rock. Therefore, research on the distribution pattern of Indosinian granitoids and factors favorable to uranium ore-formation should be enhanced during prospecting in southern China. (author)

The geological map of Uruguay

International Nuclear Information System (INIS)

Bossi, J.; Ferrando, L.; Fernandez, A.; Elizalde, G.; Morales, H.; Ledesma, J.; Carballo, E.; Medina, E.; Ford, I.; Montana, J.

1975-01-01

The geological map of Uruguay is about the morphological characteristics of the soil such as rocks, sediments and granites belong to different periods. These periods are the proterozoic, paleozoic, permian, mesozoic, jurassic, cretaceous, cenozoic and holocene.

Mesozoic evolution of the Tisza Mega-unit

Science.gov (United States)

Haas, János; Péró, Csaba

The south-eastern part of the basement of the Pannonian Basin is made up of Variscan crystalline complexes and early Mesozoic formations showing striking affinity with the corresponding formations in the southern margin of the European Plate. This large composite structural unit, which is actually an exotic terrane of European Plate origin, has been named the Tisza Mega-unit. Based upon relevant data of the pre-Tertiary basement of southern Hungary the reconstruction of the position of the Tisza Terrane in the early Alpine evolutionary stages, the process of its separation and break-off from the European Plate, and results of its Eo-Alpine deformations are summarised in the present paper. In the Variscan and early Alpine evolutionary stages the area of the later Tisza Mega-unit was located at the margin of the European Plate. During Variscan orogeny terrane accretion led to intensive deformation and metamorphism in this belt. This was followed by transpressional tectonics and the development of molasse basins in the late and post-Variscan stages, and passive margin evolution after the Neotethys opening in the Middle Triassic. The separation of the Tisza Mega-unit began with incipient continental rifting along the axis of the later Ligurian-Penninic-Vahic oceanic branch in the Late Triassic. The end of terrigenous material deposition in the most external zones, and a coeval change in fossil assemblage, point to the separation of the Tisza Block from the European Plate in the Early Bathonian. Significant rotation of the Tisza Mega-unit and coeval paroxysm of alkaline rift-type basalt volcanism took place in the Early Cretaceous. In the mid-Cretaceous, due to the northward motion of the Adria Block and the related closure of the westernmost Neotethys basin, the extensional regime changed to a compressional one, leading to onset of the nappe stacking and low-grade regional metamorphism within the Tisza microplate. In the foreland of the nappe systems flexural basins

2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal; Dossier 2005: Granite. Tome evolution phenomenologique du stockage geologique

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal; Dossier 2005: Granite. Tome evolution phenomenologique du stockage geologique

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

Evolution of Northeastern Mexico during the early Mesozoic: potential areas for research and exploration José Rafael Barboza-Gudiño

Science.gov (United States)

Barboza-Gudiño, R.

2013-05-01

Huayacocotla formations). The Middle to Upper Jurassic La Joya Formation overlies unconformable all continental and marine-marginal successions and older rocks, and records the transgressive basal deposits of the Gulf series, changing upsection to the evaporites and limestone of the Oxfordian Zuloaga Group. Successive intraoceanic subduction zones to the West sparked magmatic arcs whose accretion in the continental margin produced the consolidation of much of the Mexican territory up to the current Pacific margin. Scattered isolated outcrops from the Early Mesozoic succession in central- and northeastern Mexico allow interpretation of tectonic setting and paleogeography associated to each stratigraphic unit, revealing a strongly different geologic evolution than the previously established models, opening a range of new possibilities and areas of opportunity for mining and fossil fuels exploration. However, most of the Triassic-Jurassic rocks or stratigraphic units in northern Mexico lie under many hundreds of meters of a Cretaceous-Cenozoic cover. Their recognition and preliminary evaluation implies the use of indirect techniques like geophysical methods, before drilling or subsurface mining.

Late Mesozoic basin and range tectonics and related magmatism in Southeast China

Directory of Open Access Journals (Sweden)

Dezi Wang

2012-03-01

Full Text Available During the Late Mesozoic Middle Jurassic–Late Cretaceous, basin and range tectonics and associated magmatism representative of an extensional tectonic setting was widespread in southeastern China as a result of Pacific Plate subduction. Basin tectonics consists of post-orogenic (Type I and intra-continental extensional basins (Type II. Type I basins developed in the piedmont and intraland during the Late Triassic to Early Jurassic, in which coarse-grained terrestrial clastic sediments were deposited. Type II basins formed during intra-continental crustal thinning and were characterized by the development of grabens and half-grabens. Graben basins were mainly generated during the Middle Jurassic and were associated with bimodal volcanism. Sediments in half-grabens are intercalated with rhyolitic tuffs and lavas and are Early Cretaceous in age with a dominance of Late Cretaceous–Paleogene red beds. Ranges are composed of granitoids and bimodal volcanic rocks, A-type granites and dome-type metamorphic core complexes. The authors analyzed lithological, geochemical and geochronological features of the Late Mesozoic igneous rock assemblages and proposed some geodynamical constraints on forming the basin and range tectonics of South China. A comparison of the similarities and differences of basin and range tectonics between the eastern and western shores of the Pacific is made, and the geodynamical evolution model of the Southeast China Block during Late Mesozoic is discussed. Studied results suggest that the basin and range terrane within South China developed on a pre-Mesozoic folded belt was derived from a polyphase tectonic evolution mainly constrained by subduction of the western Pacific Plate since the Late Mesozoic, leading to formation of various magmatism in a back-arc extensional setting. Its geodynamic mechanism can compare with that of basin and range tectonics in the eastern shore of the Pacific. Differences of basin and range

Tectono-sedimentary events and geodynamic evolution of the Mesozoic and Cenozoic basins of the Alpine Margin, Gulf of Tunis, north-eastern Tunisia offshore

Science.gov (United States)

Melki, Fetheddine; Zouaghi, Taher; Chelbi, Mohamed Ben; Bédir, Mourad; Zargouni, Fouad

2010-09-01

The structural pattern, tectono-sedimentary framework and geodynamic evolution for Mesozoic and Cenozoic deep structures of the Gulf of Tunis (north-eastern Tunisia) are proposed using petroleum well data and a 2-D seismic interpretation. The structural system of the study area is marked by two sets of faults that control the Mesozoic subsidence and inversions during the Paleogene and Neogene times: (i) a NE-SW striking set associated with folds and faults, which have a reverse component; and (ii) a NW-SE striking set active during the Tertiary extension episodes and delineating grabens and subsiding synclines. In order to better characterize the tectono-sedimentary evolution of the Gulf of Tunis structures, seismic data interpretations are compared to stratigraphic and structural data from wells and neighbouring outcrops. The Atlas and external Tell belonged to the southernmost Tethyan margin record a geodynamic evolution including: (i) rifting periods of subsidence and Tethyan oceanic accretions from Triassic until Early Cretaceous: we recognized high subsiding zones (Raja and Carthage domains), less subsiding zones (Gamart domain) and a completely emerged area (Raouad domain); (ii) compressive events during the Cenozoic with relaxation periods of the Oligocene-Aquitanian and Messinian-Early Pliocene. The NW-SE Late Eocene and Tortonian compressive events caused local inversions with sealed and eroded folded structures. During Middle to Late Miocene and Early Pliocene, we have identified depocentre structures corresponding to half-grabens and synclines in the Carthage and Karkouane domains. The north-south contractional events at the end of Early Pliocene and Late Pliocene periods are associated with significant inversion of subsidence and synsedimentary folded structures. Structuring and major tectonic events, recognized in the Gulf of Tunis, are linked to the common geodynamic evolution of the north African and western Mediterranean basins.

Transformation and diversification in early mammal evolution.

Science.gov (United States)

Luo, Zhe-Xi

2007-12-13

Evolution of the earliest mammals shows successive episodes of diversification. Lineage-splitting in Mesozoic mammals is coupled with many independent evolutionary experiments and ecological specializations. Classic scenarios of mammalian morphological evolution tend to posit an orderly acquisition of key evolutionary innovations leading to adaptive diversification, but newly discovered fossils show that evolution of such key characters as the middle ear and the tribosphenic teeth is far more labile among Mesozoic mammals. Successive diversifications of Mesozoic mammal groups multiplied the opportunities for many dead-end lineages to iteratively evolve developmental homoplasies and convergent ecological specializations, parallel to those in modern mammal groups.

Field guide to the Mesozoic arc and accretionary complex of South-Central Alaska, Indian to Hatcher Pass

Science.gov (United States)

Karl, Susan M.; Oswald, P.J.; Hults, Chad P.

2015-01-01

This field trip traverses exposures of a multi-generation Mesozoic magmatic arc and subduction-accretion complex that had a complicated history of magmatic activity and experienced variations in composition and deformational style in response to changes in the tectonic environment. This Mesozoic arc formed at an unknown latitude to the south, was accreted to North America, and was subsequently transported along faults to its present location (Plafker and others, 1989; Hillhouse and Coe, 1994). Some of these faults are still active. Similar tectonic, igneous, and sedimentary processes to those that formed the Mesozoic arc complex persist today in southern Alaska, building on, and deforming the Mesozoic arc. The rocks we will see on this field trip provide insights on the three-dimensional composition of the modern arc, and the processes involved in the evolution of an arc and its companion accretionary complex.

Extreme Mesozoic crustal thinning in the Eastern Iberia margin: The example of the Columbrets Basin (Valencia Trough)

Science.gov (United States)

Mohn, G.; Etheve, N.; Frizon de Lamotte, D.; Roca, E.; Tugend, J.; Gómez-Romeu, J.

2017-12-01

Eastern Iberia preserves a complex succession of Mesozoic rifts partly or completely inverted during the Late Cretaceous and Cenozoic in relation with Africa-Eurasia convergence. Notably, the Valencia Trough, classically viewed as part of the Cenozoic West Mediterranean basins, preserves in its southwestern part a thick Mesozoic succession (locally »10km thick) over a highly thinned continental basement (locally only »3,5km thick). This sub-basin referred to as the Columbrets Basin, represents a Late Jurassic-Early Cretaceous hyper-extended rift basin weakly overprinted by subsequent events. Its initial configuration is well preserved allowing us to unravel its 3D architecture and tectono-stratigraphic evolution in the frame of the Mesozoic evolution of eastern Iberia. The Columbrets Basin benefits from an extensive dataset combining high resolution reflection seismic profiles, drill holes, refraction seismic data and Expanding Spread Profiles. Its Mesozoic architecture is controlled by interactions between extensional deformation and halokinesis involving the Upper Triassic salt. The thick uppermost Triassic to Cretaceous succession describes a general synclinal shape, progressively stretched and dismembered towards the basin borders. The SE-border of the basin is characterized by a large extensional detachment fault acting at crustal scale and interacting locally with the Upper Triassic décollement. This extensional structure accommodates the exhumation of the continental basement and part of the crustal thinning. Eventually our results highlight the complex interaction between extreme crustal thinning and occurrence of a pre-rift salt level for the deformation style and tectono-stratigraphic evolution of hyper-extended rift basins.

Geologic evolution of the SE.23 Sheet - Belo Horizonte, MG, Brazil

International Nuclear Information System (INIS)

Pereira, A.D.C.; Fonseca, E.G. da; Braz, E.R.C.

1987-01-01

The aim of this paper is to present a synthesis of the geologic evolution in the Belo Horizonte Sheet comprising an area about 281.210 Km 2 . Rb-Sr and K-Ar isotope dating methods are used for age estimation of geologic deposits. The geologic evolution of the cratonic area is reflected by a stable central nucleus surrounded by marginal orogenic belts. In the central area were recognized greenstone belts structures involved by granite terrains and bordered by a granulitic region. The framework of the Sao Francisco Craton involves events of metamorphism, granitogenesis, sedimentary, volcanism and plutonism developed in the Early to Late Proterozoic. The stratigraphic column is complemented by Late Jurassic-Early Cretaceous continental deposits belonging to Parana-Basin. (M.V.M.)

Paleoclimates and geomorphological evolution of the Carajas region: geochemical and geochronological evidence

International Nuclear Information System (INIS)

Vasconcelos, P.M.

1996-01-01

Based on the geochronological results, on the petrographical and geochemical observations and considering the experimental evidences that suggests a great influence of the organic processes in the Manganese geochemistry it's possible to conclude that the dissolution and reprecipitation events of the Manganese oxides in the Carajas region, Para State, Brazil, represents humid and hot periods in the geological history of the region. The weathering dating furnishes information about the continental evolution in the Mesozoic/Cenozoic, difficult or impossible to determine by another methods

Continental margin evolution of the northern Arabian platform in Syria

Energy Technology Data Exchange (ETDEWEB)

Best, J.A.; Barazangi, M. (Cornell Univ., Ithaca, NY (United States)); Al-Saad, D.; Sawaf, T.; Gebran, A. (Syrian Petroleum Company, Damascus (Syrian Arab Republic))

1993-02-01

Synthesis of available geological and geophysical data in the Syrian Arab Republic permits a descriptive account of the pre-Cenozoic geologic history of the northern Arabian platform. The northern Arabian platform appears to be a composite plate similar up to that interpreted in the rocks of the Arabian shield. The structural and stratigraphic relationships of the Paleozoic and Mesozoic sedimentary sections in Syria record the transformation of an eastward-facing Gondwana passive margin in the early Paleozoic into a westward-facing Levantine margin in the Mesozoic, at which time the northern platform was closely associated with the creation of the eastern Mediterranean basin. Timing of the margin transformation is inferred from the orientation and thickness variations of Lower Triassic rocks, but the transformation may have initiated as early as the Permian. The diversity and timing of geological features in Syria suggest that the northern Arabian platform did not behave as a rigid plate throughout its geological history. The present-day Palmyride mountain belt, located within the northern Arabian platform in Syria and initiated in the early Mesozoic as a northeast-trending rift nearly perpendicular to the Levantine margin, subsequently was inverted in the Cenozoic by transpression. The location of the rift may be associated with the reactivation of a zone of crustal weakness, i.e., a Proterozoic suture zone previously proposed from modeling of Bouguer gravity data. Thus, the northern and southern parts of the Arabian platform are similar in their respective geologic histories during the Proterozoic and Paleozoic; however, the northern Arabian platform was greatly affected by Mesozoic rifting and the creation of the eastern Mediterranean basin during the Mesozoic. 13 figs.

Resources for Teaching About Evolution from the U.S. Geological Survey

Science.gov (United States)

Gordon, L. C.

2001-12-01

As a scientific research agency, the U.S. Geological Survey (USGS) is in an ideal position to provide scientific information and resources to educators. The USGS is not a curriculum developer, nor an expert in pedagogy, yet the USGS does have a wealth of scientific information on subjects such as fossils, geologic time, biological resources and plate tectonics that naturally come in to play in the teaching of evolution. Among USGS resources are the general interest pamphlets Geologic Time, Dinosaurs: Facts And Fiction, Our Changing Continent, and Fossils Rocks, and Time, and its accompanying poster, Fossils Through Time. In addition to printed versions, the pamphlets are available at no cost on the Internet at http://pubs.usgs.gov/gip/. The popular booklet, This Dynamic Earth: The Story of Plate Tectonics, available at http://pubs.usgs.gov/publications/text/dynamic.html, touches on evolution-related subjects such as Alfred Wegener's use of fossils to develop his theory of continental drift, "polar" dinosaur fossils found in Australia, marine fossils in the rocks of the Himalayas, and the use of fossil ages to determine rates of plate motions. Paleontological research at the USGS is highlighted on the Internet at http://geology.er.usgs.gov/paleo/. The web site includes links to technical publications, profiles of scientists, a geologic time scale, a glossary, information on important fossil groups, and a list of non-USGS references on fossils: all very useful to educators. A wealth of biological information and data can be found in the National Biological Information Infrastructure (NBII), a multi-agency collaborative program led by the USGS. In addition to data on the Nation's biological resources, the NBII web site http://www.nbii.gov/ includes a section on systematics and scientific names (helpful for illustrating the evolutionary relationships among living organisms), and links to non-USGS curriculum materials. A fact sheet, Unveiling the NBII as a Teaching

Study on the relationships between the structural evolution and sandstone-type uranium mineralization in mesozoic era and cenozoic era in the northern of Chaidam basin

International Nuclear Information System (INIS)

Liu Lin; Song Zhe; Song Xiansheng; Feng Wei

2008-01-01

By detailed expounding the characteristics of the Mesozoic and Cenozoic structural evolution in northern of Chaidam basin, the author inquires into its relationships with the sandstone-type uranium mineralization, analyzes the prospect of forming uranium deposit, and thinks that the Mesozoic and Cenozoic strata are mainly controlled by the tectonic role of the later Yanshan movement and the later Cenozoic era. The north-west palaeo-structural slope belt is formed in the later Cretacous Epoch that is favorable for developing palaeo-interlayer oxidized zone. After the slightly extensional role of the oldest Tertiary and the early Plioeene, the middle and lower Jurassic were buried, and the block-imbricated slope belts are formed in the tectonic movement of the later Cenozoic, which are favorable for developing recent interlayer oxidized zone. According to drilling, it has the conditions for forming palaeo-recent interlayer oxidized zone sandstone-type uranium deposit at the northern of Chaidam basin. Finally, the author lays his finger on the prospecting of uranium. (authors)

Paleozoic–Mesozoic Porphyry Cu(Mo and Mo(Cu Deposits within the Southern Margin of the Siberian Craton: Geochemistry, Geochronology, and Petrogenesis (a Review

Directory of Open Access Journals (Sweden)

Anita N. Berzina

2016-11-01

Full Text Available The southern margin of the Siberian craton hosts numerous Cu(Mo and Mo(Cu porphyry deposits. This review provides the first comprehensive set of geological characteristics, geochronological data, petrochemistry, and Sr–Nd isotopic data of representative porphyry Cu(Mo and Mo(Cu deposits within the southern margin of the Siberian craton and discusses the igneous processes that controlled the evolution of these magmatic systems related to mineralization. Geochronological data show that these porphyry deposits have an eastward-younging trend evolving from the Early Paleozoic to Middle Mesozoic. The western part of the area (Altay-Sayan segment hosts porphyry Cu and Mo–Cu deposits that generally formed in the Early Paleozoic time, whereas porphyry Cu–Mo deposits in the central part (Northern Mongolia formed in the Late Paleozoic–Early Mesozoic. The geodynamic setting of the region during these mineralizing events is consistent with Early Paleozoic subduction of Paleo-Asian Ocean plate with the continuous accretion of oceanic components to the Siberian continent and Late Paleozoic–Early Mesozoic subduction of the west gulf of the Mongol–Okhotsk Ocean under the Siberian continent. The eastern part of the study area (Eastern Transbaikalia hosts molybdenum-dominated Mo and Mo–Cu porphyry deposits that formed in the Jurassic. The regional geodynamic setting during this mineralizing process is related to the collision of the Siberian and North China–Mongolia continents during the closure of the central part of the Mongol–Okhotsk Ocean in the Jurassic. Available isotopic data show that the magmas related to porphyritic Cu–Mo and Mo–Cu mineralization during the Early Paleozoic and Late Paleozoic–Early Mesozoic were mainly derived from mantle materials. The generation of fertile melts, related to porphyritic Mo and Mo–Cu mineralization during the Jurassic involved variable amounts of metasomatized mantle source component, the

Petrogeochemistry of Mesozoic basaltic volcanics in Daqingshan area

International Nuclear Information System (INIS)

Li Xiaoguang; Li Ziying; Wei Sanyuan; Qi Da'neng

2009-01-01

Through the discussion on petrogeochemistry of Later Mesozoic basaltic volcanics in Daqingshan Basin in Manzhouli area, combined with field observation and the predecessors' study, its magma evolution,genesis and diagenetic structural environment are discussed, and some suggestion are provided for the further work. Basaltic magma in this area is believed to be derived from mantle with incompatible elements which were later participated by some crustal materials. It is a partially melting product of mantle by early metasomatized fluid under lithosphere extension. Through petrogeochemical analysis of the volcanics and the contrast to the adjacent uranium-producing volcanics, it is concluded that this region has structural environment to form magma evolution series which are more favorable for volcanic hydrothermal-type uranium and polymetallic mineralization. (authors)

Geologic environmental study

International Nuclear Information System (INIS)

Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Park, Byung Yoon; Koh, Young Kown; Chun, Kwan Sik; Kim, Jhin Wung

2000-05-01

The geoscience research works are focused on the production of geologic basic data accompanying with the technical development of geology and hydrogeologic characterization. The lithology of the Korean peninsula consists of a complex structure of 29 rock types from Archean to Quaternary. The wide distribution of Mesozoic plutonic rock is an important consideration as a potential host rock allowing flexibility of siting. The recent tectonic activities are limited to localized particular area, which can be avoided by excluding in the early stage of siting. Three rock types such as plutonic rocks, crystalline gneisses and massive volcanic rocks were suggested as the preferred host rocks for the further study on HLW disposal system. This report contains grouping of regional faults, and on the distributional characteristics of faults and fractures(zones) in terms of lithological domain and tectonical provinces. The regional groundwater regime can be grouped into 3 regimes by tectonic setting and four groundwater regions based on an altitute. Groundwaters can be grouped by their chemistry and host rocks. The origin of groundwater was proposed by isotope ( 1 8O, 2 H, 1 3C, 3 4S, 8 7Sr, 1 5N) studies and the residence time of groundwater was inferred from their tritium contents. Based on the geochemical and isotope characteristics, the geochemical evolutions of each types of groundwater were simulated using SOLVEQ/CHILLER and PHREEQC programs

The Heavy Links between Geological Events and Vascular Plants Evolution: A Brief Outline.

Science.gov (United States)

Piombino, Aldo

2016-01-01

Since the rise of photosynthesis, life has influenced terrestrial atmosphere, particularly the O2 and the CO2 content (the latter being originally more than 95%), changing the chemistry of waters, atmosphere, and soils. Billions of years after, a far offspring of these first unicellular forms conquered emerging lands, not only completely changing landscape, but also modifying geological cycles of deposition and erosion, many chemical and physical characteristics of soils and fresh waters, and, more, the cycle of various elements. So, there are no doubts that vascular plants modified geology; but it is true that also geology has affected (and, more, has driven) plant evolution. New software, PyRate, has determined vascular plant origin and diversification through a Bayesian analysis of fossil record from Silurian to today, particularly observing their origination and extinction rate. A comparison between PyRate data and geological history suggests that geological events massively influenced plant evolution and that also the rise of nonflowering seed plants and the fast diffusion of flowering plants can be explained, almost partly, with the environmental condition changes induced by geological phenomena.

Geological factors of deposit formation

International Nuclear Information System (INIS)

Grushevoj, G.V.

1980-01-01

Geologic factors of hydrogenic uranium deposit formation are considered. Structural, formation and lithological-facies factors of deposit formation, connected with zones of stratal oxidation, are characterized. Peculiarities of deposit localization, connected with orogenic structures of Mesozoic and lenozoic age, are described. It is noted that deposits of anagenous group are widely spread in Paleozoic formations, infiltration uranium deposits are localized mainly in Cenozoic sediments, while uranium mineralization both anagenous and infiltration groups are widely developed in Mesozoic sediments. Anagenous deposits were formed in non-oxygen situation, their age varies from 200 to 55 mln years. Infiltration deposit formation is determined by asymmetric oxidation zonation, their age varies from 10 - 40 mln years to dozens of thousand years [ru

The first iguanian lizard from the Mesozoic of Africa

Science.gov (United States)

Daza, Juan D.; Simões, Tiago R.; Rage, Jean Claude

2016-01-01

The fossil record shows that iguanian lizards were widely distributed during the Late Cretaceous. However, the biogeographic history and early evolution of one of its most diverse and peculiar clades (acrodontans) remain poorly known. Here, we present the first Mesozoic acrodontan from Africa, which also represents the oldest iguanian lizard from that continent. The new taxon comes from the Kem Kem Beds in Morocco (Cenomanian, Late Cretaceous) and is based on a partial lower jaw. The new taxon presents a number of features that are found only among acrodontan lizards and shares greatest similarities with uromastycines, specifically. In a combined evidence phylogenetic dataset comprehensive of all major acrodontan lineages using multiple tree inference methods (traditional and implied weighting maximum-parsimony, and Bayesian inference), we found support for the placement of the new species within uromastycines, along with Gueragama sulamericana (Late Cretaceous of Brazil). The new fossil supports the previously hypothesized widespread geographical distribution of acrodontans in Gondwana during the Mesozoic. Additionally, it provides the first fossil evidence of uromastycines in the Cretaceous, and the ancestry of acrodontan iguanians in Africa. PMID:27703708

The Rb/Sr ages for granitoids of the Middle Chukotka: a new approach to the geological history of the region

International Nuclear Information System (INIS)

Efremov, S.V.; Kozlov, V.D.; Sandimirova, G.P.

2000-01-01

For studying the history of geological evolution of the Middle Chukotka in the Mesozoic by the method of Rb-Sr dating the age of granitoids in the region was determined. It was ascertained that the granitoids have different genetic nature, their formation involving the most intensive tectonic restructuring. Magmatism was manifested in two stages. Formation of the first stage granitoids (126-144 mln. years) relates to orogenesis, while that of the second stage granitoids (∼ 80 mln. years) - to the process of the Chukotka folded region activation [ru

MESOZOIC MAGMATISM IN EAST URUGUAY: PETROLOGICAL CONSTRAINTS RELATED TO THE SIERRA SAN MIGUEL REGION

Directory of Open Access Journals (Sweden)

Conti Bruno

2009-07-01

Full Text Available This work presents new results of a detailed geological and structural investigation focusing the easternmost Uruguayan Mesozoic magmatic occurrences related to the south Atlantic opening. Lithological descriptions, their stratigraphic relationships and complimentary lithochemical characterizations carried out in the San Miguel region (East Uruguay are presented. Three volcanic/sub-volcanic units have been recognized. The felsic volcanic association is composed by rhyolitic - dacitic flows, mainly with porphyritic textures and sub-alkalinenature and related pyroclastic rocks. The felsic sub-volcanic association is characterized by granophyres of about 25 km2 of exposed area, cross- cut by mafic and felsic dykes. Finally, a mafic association has been identified characterized by dykes and a small intrusion of gabbroic composition.All these units are Mesozoic in age (130 - 127 Ma and according to their chemical nature they correspond tosub-alkaline to weak peralkaline magmas.

Pelvis morphology suggests that early Mesozoic birds were too heavy to contact incubate their eggs.

Science.gov (United States)

Charles Deeming, D; Mayr, Gerald

2018-02-27

Numerous new fossils have driven an interest in reproduction of early birds, but direct evidence remains elusive. No Mesozoic avian eggs can be unambiguously assigned to a species, which hampers our understanding of the evolution of contact incubation, which is a defining feature of extant birds. Compared to living species, eggs of Mesozoic birds are relatively small, but whether the eggs of Mesozoic birds could actually have borne the weight of a breeding adult has not yet been investigated. We estimated maximal egg breadth for a range of Mesozoic avian taxa from the width of the pelvic canal defined by the pubic symphysis. Known elongation ratios of Mesozoic bird eggs allowed us to predict egg mass and hence the load mass an egg could endure before cracking. These values were compared to the predicted body masses of the adult birds based on skeletal remains. Based on 21 fossil species, we show that for nonornithothoracine birds body mass was 187% of the load mass of the eggs. For Enantiornithes, body mass was 127% greater than the egg load mass, but some early Cretaceous ornithuromorphs were 179% heavier than their eggs could support. Our indirect approach provides the best evidence yet that early birds could not have sat on their eggs without running the risk of causing damage. We suggest that contact incubation evolved comparatively late in birds. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

The geological evolution of opalinus clay in the Zurcher Weinland Area (ne Switzerland): learning from the past to predict future evolution and stability

International Nuclear Information System (INIS)

Gautschi, A.; Mazurek, M.

2004-01-01

A number of safety-relevant issues need to be addressed when considering long-term evolution of a radioactive waste repository, out of which uplift/erosion, fault activity, and changes in the geochemical and hydrogeological environment are particularly important. Among the strongest arguments in the prediction of future evolution is the extrapolation of events and processes that occurred over a long period of time in the geological past (e.g. 10 Ma) to a shorter period in the future. The future long-term evolution of Opalinus Clay in a potential siting area for a high-level waste repository in the Zurcher Weinland (NE Switzerland) is considered over a time period of around l Ma. The geological evolution or geological stability, respectively, can be predicted plausibly within reasonable limits over such a time period based on a detailed analysis of geological history. Predictions extending beyond this time period are feasible but contain an increasing element of uncertainty. This paper summarises the project-related conclusions, which are presented in greater detail in Nagra (2002a). (author)

Overview of geology and tectonic evolution of the Baikal-Tuva area.

Science.gov (United States)

Gladkochub, Dmitry; Donskaya, Tatiana

2009-01-01

This chapter provides the results of geological investigations of the main tectonic units of the Baikal-Tuva region (southwestern part of Siberia) during the last decades: the ancient Siberian craton and adjacent areas of the Central Asian Orogenic belt. In the framework of these main units we describe small-scale blocks (terranes) with focus on details of their inner structure and evolution through time. As well as describing the geology and tectonics of the area studied, we give an overview of underwater sediments, neotectonics, and some phenomena of history and development of the Baikal, Khubsugul, Chargytai, and Tore-Chol Lakes basins of the Baikal-Tuva region. It is suggested that these lakes' evolution was controlled by neotectonic processes, modern seismic activity, and global climate changes.

The geological map of Canelones Department scale 1:1000.000

International Nuclear Information System (INIS)

Spoturno, J.; Oyhantcabal, P.; Goso, C.; Aubet, N.; Cazaux; S; Huelmo, S.; Morales, E.; Loureiro, J.

2004-01-01

The geological map of Canelones Department (Uruguay), scale 1:100.000 is presented. This map shows the distribution of the proterozoic, mesozoic and cenozoic lithological units. A stratigraphic division of this region is included [es

The geological map of Montevideo Department scale 1:50.000

International Nuclear Information System (INIS)

Spoturno, J.; Oyhantcabal, P.; Goso, C.; Aubet, N.; Cazaux; S; Huelmo, S.; Morales, E.; Loureiro, J.

2004-01-01

The geological map of Montevideo Department (Uruguay), scale 1:50.000 is presented. This map shows the distribution of the proterozoic, mesozoic and cenozoic lithological units. A stratigraphic division of this region is included [es

Geological slow evolution scenari, applied on clay site of Mol (Belgium)

International Nuclear Information System (INIS)

Vandenberghe, Noel

1981-01-01

In the frame of safety assessment studies concerning radioactive waste disposal in a clay layer, the analysis of tertiary and quaternary geological history of the area involved at Mol, Belgium, showed that amongst slow natural phenomena, major climatic changes (e.g. glaciations) and epeirogenetic movements are the most important. These two phenomena result in glacio-eustatic movements, fluviatile, marine and glacial erosion etc. On the basis of their intensities and frequencies, observed in the past, several possible scenarios of future geological evolution have been considered for the coming 200.000 years. This approach contributed to evaluate the failure possibilities of the geological barrier, due to the direct action of these processes. It also demonstrates the geological frame to be taken into account in a consequence analysis

Geologic environmental study

Energy Technology Data Exchange (ETDEWEB)

Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Park, Byung Yoon; Koh, Young Kown; Chun, Kwan Sik; Kim, Jhin Wung

2000-05-01

The geoscience research works are focused on the production of geologic basic data accompanying with the technical development of geology and hydrogeologic characterization. The lithology of the Korean peninsula consists of a complex structure of 29 rock types from Archean to Quaternary. The wide distribution of Mesozoic plutonic rock is an important consideration as a potential host rock allowing flexibility of siting. The recent tectonic activities are limited to localized particular area, which can be avoided by excluding in the early stage of siting. Three rock types such as plutonic rocks, crystalline gneisses and massive volcanic rocks were suggested as the preferred host rocks for the further study on HLW disposal system. This report contains grouping of regional faults, and on the distributional characteristics of faults and fractures(zones) in terms of lithological domain and tectonical provinces. The regional groundwater regime can be grouped into 3 regimes by tectonic setting and four groundwater regions based on an altitute. Groundwaters can be grouped by their chemistry and host rocks. The origin of groundwater was proposed by isotope ({sup 1}8O, {sup 2}H, {sup 1}3C, {sup 3}4S, {sup 8}7Sr, {sup 1}5N) studies and the residence time of groundwater was inferred from their tritium contents. Based on the geochemical and isotope characteristics, the geochemical evolutions of each types of groundwater were simulated using SOLVEQ/CHILLER and PHREEQC programs.

Largest known Mesozoic multituberculate from Eurasia and implications for multituberculate evolution and biology.

Science.gov (United States)

Xu, Li; Zhang, Xingliao; Pu, Hanyong; Jia, Songhai; Zhang, Jiming; Lü, Junchang; Meng, Jin

2015-10-22

A new multituberculate, Yubaartar zhongyuanensis gen. and sp. nov., is reported from the Upper Cretaceous of Luanchuan County, Henan Province, China. The holotype of the new taxon is a partial skeleton with nearly complete cranium and associated lower jaws with in situ dentitions. The new species is the southern-most record of a Late Cretaceous multituberculate from outside of the Mongolian Plateau in Asia and represents the largest known Mesozoic multituberculate from Eurasia. The new specimen displays some intriguing features previously unknown in multituberculates, such as the first evidence of replacement of the ultimate upper premolar and a unique paleopathological case in Mesozoic mammals in which the animal with a severely broken right tibia could heal and survive in natural condition. The phylogenetic analysis based on craniodental characters places Yubaartar as the immediate outgroup of Taeniolabidoidea, a group consisting of a North American clade and an Asian clade. This relationship indicates at least a faunal interchange of multituberculates before the K-Pg transition. The new evidence further supports the hypothesis that disparity in dental complexity, which relates to animal diets, increased with generic richness and disparity in body size, and that an adaptive shift towards increased herbivory across the K-Pg transitional interval.

Preliminary Depositional and Provenance Records of Mesozoic Basin Evolution and Cenozoic Shortening in the High Andes, La Ramada Fold-Thrust Belt, Southern-Central Andes (32-33°S)

Science.gov (United States)

Mackaman-Lofland, C.; Horton, B. K.; Fuentes, F.; Constenius, K. N.; McKenzie, R.; Alvarado, P. M.

2015-12-01

The Argentinian Andes define key examples of retroarc shortening and basin evolution above a zone of active subduction. The La Ramada fold-thrust belt (RFTB) in the High Andes provides insights into the relative influence and temporal records of diverse convergent margin processes (e.g. flat-slab subduction, convergent wedge dynamics, structural inversion). The RFTB contains Mesozoic extensional basin strata deformed by later Andean shortening. New detrital zircon U-Pb analyses of Mesozoic rift sediments reveal: (1) a dominant Permo-Triassic age signature (220-280 Ma) associated with proximal sources of effective basement (Choiyoi Group) during Triassic synrift deposition; (2) upsection younging of maximum depositional ages from Late Triassic through Early Cretaceous (230 to 100 Ma) with the increasing influence of western Andean arc sources; and (3) a significant Late Cretaceous influx of Paleozoic (~350-550 Ma) and Proterozoic (~650-1300 Ma) populations during the earliest shift from back-arc post-extensional subsidence to upper-plate shortening. The Cenozoic detrital record of the Manantiales foreland basin (between the Frontal Cordillera and Precordillera) records RFTB deformation prior to flat-slab subduction. A Permo-Triassic Choiyoi age signature dominates the Miocene succession, consistent with sources in the proximal Espinacito range. Subordinate Mesozoic (~80-250 Ma) to Proterozoic (~850-1800 Ma) U-Pb populations record exhumation of the Andean magmatic arc and recycling of different structural levels in the RFTB during thrusting/inversion of Mesozoic rift basin strata and subjacent Paleozoic units. Whereas maximum depositional ages of sampled Manantiales units cluster at 18-20 Ma, the Estancia Uspallata basin (~50 km to the south) shows consistent upsection younging of Cenozoic populations attributed to proximal volcanic centers. Ongoing work will apply low-temperature thermochronology to pinpoint basin accumulation histories and thrust timing.

Bone-eating Osedax worms lived on Mesozoic marine reptile deadfalls.

Science.gov (United States)

Danise, Silvia; Higgs, Nicholas D

2015-04-01

We report fossil traces of Osedax, a genus of siboglinid annelids that consume the skeletons of sunken vertebrates on the ocean floor, from early-Late Cretaceous (approx. 100 Myr) plesiosaur and sea turtle bones. Although plesiosaurs went extinct at the end-Cretaceous mass extinction (66 Myr), chelonioids survived the event and diversified, and thus provided sustenance for Osedax in the 20 Myr gap preceding the radiation of cetaceans, their main modern food source. This finding shows that marine reptile carcasses, before whales, played a key role in the evolution and dispersal of Osedax and confirms that its generalist ability of colonizing different vertebrate substrates, like fishes and marine birds, besides whale bones, is an ancestral trait. A Cretaceous age for unequivocal Osedax trace fossils also dates back to the Mesozoic the origin of the entire siboglinid family, which includes chemosynthetic tubeworms living at hydrothermal vents and seeps, contrary to phylogenetic estimations of a Late Mesozoic-Cenozoic origin (approx. 50-100 Myr). © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Porphyry copper assessment of the Mesozoic of East Asia: China, Vietnam, North Korea, Mongolia, and Russia: Chapter G in Global mineral resource assessment

Science.gov (United States)

Ludington, Steve; Mihalasky, Mark J.; Hammarstrom, Jane M.; Robinson, Giplin R.; Frost, Thomas P.; Gans, Kathleen D.; Light, Thomas D.; Miller, Robert J.; Alexeiev, Dmitriy V.

2012-01-01

The U.S. Geological Survey (USGS) collaborated with the China Geological Survey (CGS) to conduct a mineral resource assessment of Mesozoic porphyry copper deposits in East Asia. This area hosts several very large porphyry deposits, exemplified by the Dexing deposit in eastern China that contains more than 8,000,000 metric tons of copper. In addition, large parts of the area are undergoing active exploration and are likely to contain undiscovered porphyry copper deposits.

Evolution and Adaptation of Phytoplankton Photosynthetic Pathways to perturbations of the geological carbon system

Science.gov (United States)

Rickaby, R. E.; Young, J. N.; Hermoso, M.; Heureux, A.; McCLelland, H.; Lee, R.; Eason Hubbard, M.

2012-12-01

The ocean and atmosphere carbon system has varied greatly over geological history both in response to initial evolutionary innovation, and as a driver of adaptive change. Here we establish that positive selection in Rubisco, the most abundant enzyme on the Earth responsible for all photosynthetic carbon fixation, occurred early in Earth's history, and basal to the radiation of the modern marine algal groups. Our signals of positive selection appear to be triggered by changing intracellular concentrations of carbon dioxide (CO2) due to the emergence of carbon concentrating mechanisms between 1.56 and 0.41 Ba in response to declining atmospheric CO2 . We contend that, at least in terms of carbon, phytoplankton generally were well poised to manage subsequent abrupt carbon cycle perturbations. The physiological pathways for optimising carbon acquisition across a wide range of ambient carbon dioxide concentrations had already been established and were genetically widespread across open ocean phytoplankton groups. We will further investigate some case studies from the Mesozoic and Cenozoic abrupt carbon cycle excursions using isotopic tools to probe the community photosynthetic response and demonstrate the flexibility of phytoplankton photosynthesis in the face of major perturbations. In particular, an unprecedented resolution record across the Toarcian (Early Jurassic) carbon isotope excursion in the Paris Basin reveals a selection and evolution towards a community reliant solely on diffusive carbon dioxide supply for photosynthesis at the height of the excursion at 1500-2500 ppm CO2. The continued flourishing of the phytoplankton biological pump throughout this excursion was able to remove the excess carbon injected into the water column in less than 45 kyrs.

Paleozoic–early Mesozoic gold deposits of the Xinjiang Autonomous Region, northwestern China

Science.gov (United States)

Rui, Zongyao; Goldfarb, Richard J.; Qiu, Yumin; Zhou, T.; Chen, R.; Pirajno, Franco; Yun, Grace

2002-01-01

The late Paleozoic–early Mesozoic tectonic evolution of Xinjiang Autonomous Region, northwestern China provided a favorable geological setting for the formation of lode gold deposits along the sutures between a number of the major Eastern Asia cratonic blocks. These sutures are now represented by the Altay Shan, Tian Shan, and Kunlun Shan ranges, with the former two separated by the Junggar basin and the latter two by the immense Tarim basin. In northernmost Xinjiang, final growth of the Altaid orogen, southward from the Angara craton, is now recorded in the remote mid- to late Paleozoic Altay Shan. Accreted Early to Middle Devonian oceanic rock sequences contain typically small, precious-metal bearing Fe–Cu–Zn VMS deposits (e.g. Ashele). Orogenic gold deposits are widespread along the major Irtysh (e.g. Duyolanasayi, Saidi, Taerde, Kabenbulake, Akexike, Shaerbulake) and Tuergen–Hongshanzui (e.g. Hongshanzui) fault systems, as well as in structurally displaced terrane slivers of the western Junggar (e.g. Hatu) and eastern Junggar areas. Geological and geochronological constraints indicate a generally Late Carboniferous to Early Permian episode of gold deposition, which was coeval with the final stages of Altaid magmatism and large-scale, right-lateral translation along older terrane-bounding faults. The Tian Shan, an exceptionally gold-rich mountain range to the west in the Central Asian republics, is only beginning to be recognized for its gold potential in Xinjiang. In this easternmost part to the range, northerly- and southerly-directed subduction/accretion of early to mid-Paleozoic and mid- to late Paleozoic oceanic terranes, respectively, to the Precambrian Yili block (central Tian Shan) was associated with 400 to 250 Ma arc magmatism and Carboniferous through Early Permian gold-forming hydrothermal events. The more significant resulting deposits in the terranes of the southern Tian Shan include the Sawayaerdun orogenic deposit along the Kyrgyzstan

[Proceedings of the symposium 'Molluscan Palaeontology' : 11th International Malacological Congress, Siena (Italy) 30th August - 5th September 1992 / A.W. Janssen and R. Janssen (editors)]: The Mesozoic Marine Revolution and epifaunal bivalves

NARCIS (Netherlands)

Harper, E.M.; Skelton, P.W.

1992-01-01

The well documented dramatic increase in predation pressure which started during the early Mesozoic, termed the Mesozoic Marine Revolution (MMR), had an important impact on the evolution of prey organisms (Vermeij, 1983). Epifaunal bivalves in particular are at considerable risk to predation. In

Mesozoic and Cenozoic structural geology of the CP Hills, Nevada Test Site, Nye County, Nevada; and regional implications

Energy Technology Data Exchange (ETDEWEB)

Caskey, S. John [Univ. of Nevada, Reno, NV (United States)

1991-08-01

Detailed mapping and structural analysis of upper Proterozoic and Paleozoic rocks in the CP Hills of the Nevada Test Site, together with analysis of published maps and cross sections and a reconnaissance of regional structural relations indicate that the CP thrust of Barnes and Poole (1968) actually comprises two separate, oppositely verging Mesozoic thrust systems: (1) the west-vergent CP thrust which is well exposed in the CP Hills and at Mine Mountain, and (2) the east-vergent Belted Range thrust located northwest of Yucca Flat. West-vergence of the CP thrust is indicated by large scale west-vergent recumbent folds in both its hangingwall and footwall and by the fact that the CP thrust ramps up section through hangingwall strata toward the northwest. Regional structural relations indicate that the CP thrust forms part of a narrow sigmoidal belt of west-vergent folding and thrusting traceable for over 180 km along strike. The Belted Range thrust represents earlier Mesozoic deformation that was probably related to the Last Chance thrust system in southeastern California, as suggested by earlier workers. A pre-Tertiary reconstruction of the Cordilleran fold and thrust belt in the region between the NTS and the Las Vegas Range bears a close resemblance to other regions of the Cordillera and has important implications for the development of hinterland-vergent deformation as well as for the probable magnitude of Tertiary extension north of Las Vegas Valley. Subsequent to Mesozoic deformation, the CP Hills were disrupted by at least two episodes of Tertiary extensional deformation: (1) an earlier episode represented by pre-middle Miocene low-angle normal faults, and (2) a later, post-11 Ma episode of high-angle normal faulting. Both episodes of extension were related to regional deformation, the latter of which has resulted in the present basin and range topography of the NTS region.

Mesozoic and Cenozoic structural geology of the CP Hills, Nevada Test Site, Nye County, Nevada; and regional implications

International Nuclear Information System (INIS)

Caskey, S.J.

1991-08-01

Detailed mapping and structural analysis of upper Proterozoic and Paleozoic rocks in the CP Hills of the Nevada Test Site, together with analysis of published maps and cross sections and a reconnaissance of regional structural relations indicate that the CP thrust of Barnes and Poole (1968) actually comprises two separate, oppositely verging Mesozoic thrust systems: (1) the west-vergent CP thrust which is well exposed in the CP Hills and at Mine Mountain, and (2) the east-vergent Belted Range thrust located northwest of Yucca Flat. West-vergence of the CP thrust is indicated by large scale west-vergent recumbent folds in both its hangingwall and footwall and by the fact that the CP thrust ramps up section through hangingwall strata toward the northwest. Regional structural relations indicate that the CP thrust forms part of a narrow sigmoidal belt of west-vergent folding and thrusting traceable for over 180 km along strike. The Belted Range thrust represents earlier Mesozoic deformation that was probably related to the Last Chance thrust system in southeastern California, as suggested by earlier workers. A pre-Tertiary reconstruction of the Cordilleran fold and thrust belt in the region between the NTS and the Las Vegas Range bears a close resemblance to other regions of the Cordillera and has important implications for the development of hinterland-vergent deformation as well as for the probable magnitude of Tertiary extension north of Las Vegas Valley. Subsequent to Mesozoic deformation, the CP Hills were disrupted by at least two episodes of Tertiary extensional deformation: (1) an earlier episode represented by pre-middle Miocene low-angle normal faults, and (2) a later, post-11 Ma episode of high-angle normal faulting. Both episodes of extension were related to regional deformation, the latter of which has resulted in the present basin and range topography of the NTS region

Geology of Sierra de San Miguel area Rocha department (Uruguay)

International Nuclear Information System (INIS)

Muzio, R.; Veroslavsky, G.; Morales, E. . E mail: rossana@fcien.edu.uy

2004-01-01

This paper is part of a regional study about Mesozoic magmatism, tectonics and sedimentation in Uruguay. As a result of the geological studies carried out in Sierra de San Miguel area (Rocha department), lithological descriptions, their stratigraphic relationships and their petrographic characterization are presented [es

Predictability of the evolution of hydrogeological and hydrogeochemical systems; geological disposal of nuclear waste in crystalline rocks

International Nuclear Information System (INIS)

Murphy, W.M.; Diodato, D.M.

2009-01-01

Confidence in long-term geologic isolation of high-level nuclear waste and spent nuclear fuel requires confidence in predictions of the evolution of hydrogeological and hydrogeochemical systems. Prediction of the evolution of hydrogeological and hydrogeochemical systems is based on scientific understanding of those systems in the present - an understanding that can be tested with data from the past. Crystalline rock settings that have been geologically stable for millions of years and longer offer the potential of predictable, long-term waste isolation. Confidence in predictions of geologic isolation of radioactive waste can measured by evaluating the extent to which those predictions and their underlying analyses are consistent with multiple independent lines of evidence identified in the geologic system being analysed, as well as with evidence identified in analogs to that geologic system. The proposed nuclear waste repository at Yucca Mountain, Nevada, United States, differs in significant ways from potential repository sites being considered by other nations. Nonetheless, observations of hydrogeological and hydrogeochemical systems of Yucca Mountain and Yucca Mountain analogs present multiple independent lines of evidence that can be used in evaluating long-term predictions of the evolution of hydrogeological and hydrogeochemical systems at Yucca Mountain. (authors)

Geological and rock mechanics aspects of the long-term evolution of a crystalline rock site

International Nuclear Information System (INIS)

Cosgrove, J.W.; Hudson, J.A.

2009-01-01

We consider the stability of a crystalline rock mass and hence the integrity of a radioactive waste repository contained therein by, firstly, identifying the geological evolution of such a site and, secondly, by assessing the likely rock mechanics consequences of the natural perturbations to the repository. In this way, the potency of an integrated geological-rock mechanics approach is demonstrated. The factors considered are the pre-repository geological evolution, the period of repository excavation, emplacement and closure, and the subsequent degradation and natural geological perturbations introduced by glacial loading. It is found that the additional rock stresses associated with glacial advance and retreat have a first order effect on the stress magnitudes and are likely to cause a radical change in the stress regime. There are many factors involved in the related geosphere stability and so the paper concludes with a systems diagram of the total evolutionary considerations before, during and after repository construction. (authors)

The potential impact of geological environment on health status of residents of the Slovak Republic.

Science.gov (United States)

Rapant, S; Cvečková, V; Dietzová, Z; Fajčíková, K; Hiller, E; Finkelman, R B; Škultétyová, S

2014-06-01

In order to assess the potential impact of the geological environment on the health of the population of the Slovak Republic, the geological environment was divided into eight major units: Paleozoic, Crystalline, Carbonatic Mesozoic and basal Paleogene, Carbonatic-silicate Mesozoic and Paleogene, Paleogene Flysch, Neovolcanics, Neogene and Quaternary sediments. Based on these geological units, the databases of environmental indicators (chemical elements/parameters in groundwater and soils) and health indicators (concerning health status and demographic development of the population) were compiled. The geological environment of the Neogene volcanics (andesites and basalts) has been clearly documented as having the least favourable impact on the health of Slovak population, while Paleogene Flysch geological environment (sandstones, shales, claystones) has the most favourable impact. The most significant differences between these two geological environments were observed, especially for the following health indicators: SMRI6364 (cerebral infarction and strokes) more than 70 %, SMRK (digestive system) 55 %, REI (circulatory system) and REE (endocrine and metabolic system) almost 40 % and REC (malignant neoplasms) more than 30 %. These results can likely be associated with deficit contents of Ca and Mg in groundwater from the Neogene volcanics that are only about half the level of Ca and Mg in groundwater of the Paleogene sediments.

Geologic evolution of Tucurui region - Para

International Nuclear Information System (INIS)

Silva Matta, M.A. da.

1982-01-01

The northern part of the Araguaia Belt is exposed in the Tucurui region and their stratigraphic, structural, metamorphic and magmatic features had been studied aiming at contributing for the understanding of the geological evolution of the area. Dating with R-Sr and K-At are also presented, allowing some association for the lythotype of Xingu complex and Araguaia Belt. The oldest stratigraphic unit of the area is represented by the Xingu Complex, composed by gneisses and granites and subordinated schists and anphibolites. Over this unit, during the niddle Proterozoic, the Tucurui group was developed. The bottom of this unit is composed by a sequence of tholeiitic basaltic flows which were here enclosed in the Caripe Formation. The Morrote Formation, is made up of graywackes, and constitutes the upper part of the Tucurui Group. The geossinolinal evolution of the Araguaia Belt took place during the Uruacuano Cycle. This geoteotonic unit is represented in the studied area by the Couto Magalhaes Formation (Tocantins Group) which comprises pelitic and psamitic metasediments. After the metamorphism of the Araguaia Belt, the Couto Magalhaes Formation acted as the place of mafic and ultramafic intrusion and, lately, the Tucurui Fault thrusted the metamorphic rocks of the Tocantins Group over the Tucurui Group lithetypes. (author)

A Mesozoic orogenic cycle from post-collision to subduction in the southwestern Korean Peninsula: New structural, geochemical, and chronological evidence

Science.gov (United States)

Park, Seung-Ik; Kwon, Sanghoon; Kim, Sung Won; Hong, Paul S.; Santosh, M.

2018-05-01

The Early to Middle Mesozoic basins, distributed sporadically over the Korean Peninsula, preserve important records of the tectonic history of some of the major orogenic belts in East Asia. Here we present a comprehensive study of the structural, geochemical, geochronological, and paleontological features of a volcano-sedimentary package, belonging to the Oseosan Volcanic Complex of the Early to Middle Mesozoic Chungnam Basin, within the Mesozoic subduction-collision orogen in the southwestern Korean Peninsula. The zircon U-Pb data from rhyolitic volcanic rocks of the complex suggest Early to Middle Jurassic emplacement age of ca. 178-172 Ma, harmonious with plant fossil taxa found from the overlying tuffaceous sedimentary rock. The geochemical data for the rhyolitic volcanic rocks are indicative of volcanic arc setting, implying that the Chungnam Basin has experienced an intra-arc subsidence during the basin-expanding stage by subduction of the Paleo-Pacific (Izanagi) Plate. The Jurassic arc-related Oseosan Volcanic Complex was structurally stacked by the older Late Triassic to Early Jurassic post-collisional basin-fill of the Nampo Group by the Jangsan fault during basin inversion. The Late Jurassic to Early Cretaceous K-feldspar and illite K-Ar ages marked the timing of inversion tectonics, contemporaneous with the magmatic quiescence in the southern Korean Peninsula, likely due to flat-lying or low-angle subduction. The basin evolution history preserved in the Mesozoic Chungnam Basin reflects a Mesozoic orogenic cycle from post-collision to subduction in the southwestern Korean Peninsula. This, in turn, provides a better understanding of the spatial and temporal changes in Mesozoic tectonic environments along the East Asian continental margin.

Mesozoic Compressional Folds of the Nansha Waters, Southern South China Sea

Science.gov (United States)

Zhu, R.; Liu, H.; Yao, Y.; Wang, Y.

2017-12-01

As an important part of the South China Sea, the southern margin of the South China Sea is fundamental to understand the interaction of the Eurasian, Pacific and Indian-Australian plates and the evolution of the South China Sea. Some multi-channel seismic profiles of the Nansha waters together with published drillings and dredge data were correlated for interpretation. The strata of the study region can be divided into the upper, middle and lower structural layers. The upper and middle structural layers with extensional tectonics are Cenozoic; the lower structural layer suffered compression is Mesozoic. Further structural restoration was done to remove the Cenozoic tectonic influence and to calculate the Mesozoic tectonic compression ratios. The results indicate that two diametrically opposite orientations of compressive stress, S(S)E towards N(N)W orientation and N(N)W towards S(S)E orientation respectively, once existed in the lower structural layer of the study area and shared the same variation trend. The compression ratio values gradually decrease both from the north to the south and from the west to the east in each stress orientation. The phenomena may be related to the opening of the proto-South China Sea (then located in south of the Nansha block) and the rate of the Nansha block drifted northward in Late Jurassic to Late Cretaceous, which had pushed the Nansha block drifted northward until it collided and sutured with the Southern China Margin. Thus the opening of the present-day South China Sea may be related to this suture zone, which was tectonically weakness zone.Key words: Mesozoic compression; structural restoration; proto-South China Sea; Nansha waters; Southern South China Sea; Acknowledgements: The work was granted by the National Natural Science Foundation of China (Grant Nos. 41476039, 91328205, 41576068 and 41606080).

Structural geologic study of southeastern Missouri

International Nuclear Information System (INIS)

Satterfield, I.R.; Ward, R.A.

1978-01-01

A geologic map at 1:62,500 scale was prepared of the Cretaceous (Mesozoic) and Tertiary (cenozoic) sediments and seven major units were recognized with emphasis on faulting. Faulted sediments of Pliocene age (possibly Pleistocene) were observed and younger units are suspected to be involved. Data from hand-augered holes plus water well data were logged and plotted. The feasibility of using physical data (size analysis and pH) as a correlation tool for determining structural disturbance in loess deposits was established

Geological development and uranium and thorium evolutions in volcanic basin No.460

International Nuclear Information System (INIS)

Zhou Dean.

1989-01-01

On the basis of summarizing the geological features and the developmental history of tectono-magmatic activity, the uranium and thorium evolutional rules of rocks in different times are studied. It is suggested that the uranium and thorium increments caused by potassic migmatization of late Archean basement rocks in this area is the material base which affected the subsequent evolution of the cover of volcanic rocks and uranium mineralization. The Upper Jurassic acid volcanic cover belonging to crustal remelting origin constituted the favorable stratigraphic background for uranium mineralization in this area due to its wide distribution, large thickness, various rock associations and lithological sequences, as well as high content of uranium and thorium. During the late Yanshanian stage acid subvolanic rocks or small intrusions with high uranium intruded along the regional fractures are the decisive factors for the emplacement of uranium mineralization in this area, which othen became the favorable wall rocks for preserving ores itself. During the late stage the hydrothermal uranium mineralization was the main geological process from which uranium and thorium in stratigraphy and terrain were finally separated

Earliest filter-feeding pterosaur from the Jurassic of China and ecological evolution of Pterodactyloidea.

Science.gov (United States)

Zhou, Chang-Fu; Gao, Ke-Qin; Yi, Hongyu; Xue, Jinzhuang; Li, Quanguo; Fox, Richard C

2017-02-01

Pterosaurs were a unique clade of flying reptiles that were contemporaries of dinosaurs in Mesozoic ecosystems. The Pterodactyloidea as the most species-diverse group of pterosaurs dominated the sky during Cretaceous time, but earlier phases of their evolution remain poorly known. Here, we describe a 160 Ma filter-feeding pterosaur from western Liaoning, China, representing the geologically oldest record of the Ctenochasmatidae, a group of exclusive filter feeders characterized by an elongated snout and numerous fine teeth. The new pterosaur took the lead of a major ecological transition in pterosaur evolution from fish-catching to filter-feeding adaptation, prior to the Tithonian (145-152 Ma) diversification of the Ctenochasmatidae. Our research shows that the rise of ctenochasmatid pterosaurs was followed by the burst of eco-morphological divergence of other pterodactyloid clades, which involved a wide range of feeding adaptations that considerably altered the terrestrial ecosystems of the Cretaceous world.

New insights on the geological evolution of the continental margin of Southeastern Brazil derived from zircon and apatite (U-Th-Sm)/He and fission-track data

Science.gov (United States)

Krob, Florian; Stippich, Christian; Glasmacher, Ulrich A.; Hackspacher, Peter

2017-04-01

thermochronological data. We used the geological model of the Paraná basin supersequences (Rio Ivaí, Paraná, Gondwana I-III and Bauru) to remodel the subsidence and exhumation history of our consisting thermochronological sample data. First indications include a fast exhumation during the early Paleozoic, a slow shallow (northern blocks) to fast and deep (Laguna block) subduction from middle Paleozoic to Mesozoic time and a extremely fast exhumation during the opening of the South Atlantic (Cretaceous time). This enables a possible interpretation of the southeastern Brazilian margin being an outer part of the Paraná basin and even the possible source area for the Ordovician to Carboniferous sediments. Further on, we try to research the newly gained exhumation history models for indications on the evolution and movement of the lithosphere of the southeastern Brazilian mantle.

Evolution of waste-package design at the potential U.S. geologic repository

International Nuclear Information System (INIS)

Benton, H.; Harkins, B.

2000-01-01

This paper describes the evolution of the waste-package design at the potential geologic repository for spent nuclear fuel and high-level waste at Yucca Mountain in Nevada. Because the potential repository is the first of its kind, the design of its components must be flexible and capable of evolving in response to continuing scientific study, development efforts, and changes to performance criteria. The team of scientists and engineers at the Yucca Mountain Project has utilized a systematic, scientific approach to design the potential geologic nuclear-waste repository. As a result of continuing development efforts, the design has incorporated a growing base of scientific and engineering information to ensure that regulatory and performance requirements are met. (authors)

Analysis on metallogenetic geological and physicochemical conditions in uranium deposit No.138

International Nuclear Information System (INIS)

Tang Qitao

1996-01-01

The uranium deposit No.138 is of Mesozoic volcano-sedimentary transformation type. This paper discusses such geological conditions as source of uranium, stratigraphy and lithology, lithofacies and paleogeography, paleoclimate, structure and reworking-regeneration, and such physicochemical conditions as uranium adsorbent and reductant, effective porosity, chemical compositions, pH and Eh of rocks in the deposit

Paleozoic subduction complex and Paleozoic-Mesozoic island-arc volcano-plutonic assemblages in the northern Sierra terrane

Science.gov (United States)

Hanson, Richard E.; Girty, Gary H.; Harwood, David S.; Schweickert, Richard A.

2000-01-01

This field trip provides an overview of the stratigraphic and structural evolution of the northern Sierra terrane, which forms a significant part of the wall rocks on the western side of the later Mesozoic Sierra Nevada batholith in California. The terrane consists of a pre-Late Devonian subduction complex (Shoo Fly Complex) overlain by submarine arc-related deposits that record the evolution of three separate island-arc systems in the Late Sevonian-Early Mississippian, Permian, and Late Triassic-Jurassic. The two Paleozoic are packages and the underlying Shoo Fly Complex have an important bearing on plate-tectonic processes affecting the convergent margin outboard of the Paleozoic Cordilleran miogeocline, although their original paleogeographic relations to North America are controversial. The third arc package represents an overlap assemblage that ties the terrane to North America by the Late Triassic and helps constrain the nature and timing of Mesozoic orogenesis. Several of the field-trip stops examine the record of pre-Late Devonian subduction contained in the Shoo Fly Complex, as well as the paleovolcanology of the overlying Devonian to Jurassic arc rocks. Excellent glaciated exposures provide the opportunity to study a cross section through a tilted Devonian volcano-plutonic association. Additional stops focus on plutonic rocks emplaced during the Middle Jurassic arc magmatism in the terrane, and during the main pulse of Cretaceous magmatism in the Sierra Nevada batholith to the east.

Geology and mineral potential of Ethiopia: a note on geology and mineral map of Ethiopia

Energy Technology Data Exchange (ETDEWEB)

Tadesse, S.; Milesi, J.P.; Deschamps, Y. [University of Addis Ababa, Addis Ababa (Ethiopia). Dept. for Geology & Geophysics

2003-05-01

This work presents a geoscientific map and database for geology, mineral and energy resources of Ethiopia in a digital form at a scale of 1 : 2,000,000, compiled from several sources. The final result of the work has been recorded on CD-ROM in GIS format. Metallic resources (precious, rare, base and ferrous-ferroalloy metals) are widely related to the metamorphic meta-volcano-sedimentary belts and associated intrusives belonging to various terranes of the Arabian-Nubian Shield, accreted during the East and West Gondwana collision (Neoproterozoic, 900-500 Ma). Industrial minerals and rock resources occur in more diversified geological environments, including the Proterozoic basement rocks, the Late Paleozoic to Mesozoic sediments and recent (Cenozoic) volcanics and associated sediments. Energy resources (oil, coal, geothermal resources) are restricted to Phanerozoic basin sediments and Cenozoic volcanism and rifting areas.

Regulation of body temperature by some Mesozoic marine reptiles.

Science.gov (United States)

Bernard, Aurélien; Lécuyer, Christophe; Vincent, Peggy; Amiot, Romain; Bardet, Nathalie; Buffetaut, Eric; Cuny, Gilles; Fourel, François; Martineau, François; Mazin, Jean-Michel; Prieur, Abel

2010-06-11

What the body temperature and thermoregulation processes of extinct vertebrates were are central questions for understanding their ecology and evolution. The thermophysiologic status of the great marine reptiles is still unknown, even though some studies have suggested that thermoregulation may have contributed to their exceptional evolutionary success as apex predators of Mesozoic aquatic ecosystems. We tested the thermal status of ichthyosaurs, plesiosaurs, and mosasaurs by comparing the oxygen isotope compositions of their tooth phosphate to those of coexisting fish. Data distribution reveals that these large marine reptiles were able to maintain a constant and high body temperature in oceanic environments ranging from tropical to cold temperate. Their estimated body temperatures, in the range from 35 degrees +/- 2 degrees C to 39 degrees +/- 2 degrees C, suggest high metabolic rates required for predation and fast swimming over large distances offshore.

The fragmentation of Pangaea and Mesozoic terrestrial vertebrate biodiversity.

Science.gov (United States)

Vavrek, Matthew J

2016-09-01

During the Mesozoic (242-66 million years ago), terrestrial regions underwent a massive shift in their size, position and connectivity. At the beginning of the era, the land masses were joined into a single supercontinent called Pangaea. However, by the end of the Mesozoic, terrestrial regions had become highly fragmented, both owing to the drifting apart of the continental plates and the extremely high sea levels that flooded and divided many regions. How terrestrial biodiversity was affected by this fragmentation and large-scale flooding of the Earth's landmasses is uncertain. Based on a model using the species-area relationship (SAR), terrestrial vertebrate biodiversity would be expected to nearly double through the Mesozoic owing to continental fragmentation, despite a decrease of 24% in total terrestrial area. Previous studies of Mesozoic vertebrates have generally found increases in terrestrial diversity towards the end of the era, although these increases are often attributed to intrinsic or climatic factors. Instead, continental fragmentation over this time may largely explain any observed increase in terrestrial biodiversity. This study demonstrates the importance that non-intrinsic effects can have on the taxonomic success of a group, and the importance of geography to understanding past biodiversity. © 2016 The Author(s).

Time evolution of the Clay Barrier Chemistry in a HLW deep geological disposal in granite

International Nuclear Information System (INIS)

Font, I.; Miguel, M. J.; Juncosa, R.

2000-01-01

The main goal of a high level waste geological disposal is to guarantee the waste isolation from the biosphere, locking them away into very deep geological formations. The best way to assure the isolation is by means of a multiple barrier system. These barriers, in a serial disposition, should assure the confinement function of the disposal system. Two kinds of barriers are considered: natural barriers (geological formations) and engineered barriers (waste form, container and backfilling and sealing materials). Bentonite is selected as backfilling and sealing materials for HLW disposal into granite formations, due to its very low permeability and its ability to fill the remaining spaces. bentonite has also other interesting properties, such as, the radionuclide retention capacity by sorption processes. Once the clay barrier has been placed, the saturation process starts. The granite groundwater fills up the voids of the bentonite and because of the chemical interactions, the groundwater chemical composition varies. Near field processes, such as canister corrosion, waste leaching and radionuclide release, strongly depends on the water chemical composition. Bentonite pore water composition is such a very important feature of the disposal system and its determination and its evolution have great relevance in the HLW deep geological disposal performance assessment. The process used for the determination of the clay barrier pore water chemistry temporal evolution, and its influence on the performance assessment, are presented in this paper. (Author)

Spectra of Earth-like Planets through Geological Evolution around FGKM Stars

Science.gov (United States)

Rugheimer, S.; Kaltenegger, L.

2018-02-01

Future observations of terrestrial exoplanet atmospheres will occur for planets at different stages of geological evolution. We expect to observe a wide variety of atmospheres and planets with alternative evolutionary paths, with some planets resembling Earth at different epochs. For an Earth-like atmospheric time trajectory, we simulate planets from the prebiotic to the current atmosphere based on geological data. We use a stellar grid F0V to M8V ({T}{eff}=7000–2400 K) to model four geological epochs of Earth's history corresponding to a prebiotic world (3.9 Ga), the rise of oxygen at 2.0 Ga and at 0.8 Ga, and the modern Earth. We show the VIS–IR spectral features, with a focus on biosignatures through geological time for this grid of Sun-like host stars and the effect of clouds on their spectra. We find that the observability of biosignature gases reduces with increasing cloud cover and increases with planetary age. The observability of the visible O2 feature for lower concentrations will partly depend on clouds, which, while slightly reducing the feature, increase the overall reflectivity, and thus the detectable flux of a planet. The depth of the IR ozone feature contributes substantially to the opacity at lower oxygen concentrations, especially for the high near-UV stellar environments around F stars. Our results are a grid of model spectra for atmospheres representative of Earth's geological history to inform future observations and instrument design and are available online at http://carlsaganinstitute.org/data/.

Geology of Joshua Tree National Park geodatabase

Science.gov (United States)

Powell, Robert E.; Matti, Jonathan C.; Cossette, Pamela M.

2015-09-16

The database in this Open-File Report describes the geology of Joshua Tree National Park and was completed in support of the National Cooperative Geologic Mapping Program of the U.S. Geological Survey (USGS) and in cooperation with the National Park Service (NPS). The geologic observations and interpretations represented in the database are relevant to both the ongoing scientific interests of the USGS in southern California and the management requirements of NPS, specifically of Joshua Tree National Park (JOTR).Joshua Tree National Park is situated within the eastern part of California’s Transverse Ranges province and straddles the transition between the Mojave and Sonoran deserts. The geologically diverse terrain that underlies JOTR reveals a rich and varied geologic evolution, one that spans nearly two billion years of Earth history. The Park’s landscape is the current expression of this evolution, its varied landforms reflecting the differing origins of underlying rock types and their differing responses to subsequent geologic events. Crystalline basement in the Park consists of Proterozoic plutonic and metamorphic rocks intruded by a composite Mesozoic batholith of Triassic through Late Cretaceous plutons arrayed in northwest-trending lithodemic belts. The basement was exhumed during the Cenozoic and underwent differential deep weathering beneath a low-relief erosion surface, with the deepest weathering profiles forming on quartz-rich, biotite-bearing granitoid rocks. Disruption of the basement terrain by faults of the San Andreas system began ca. 20 Ma and the JOTR sinistral domain, preceded by basalt eruptions, began perhaps as early as ca. 7 Ma, but no later than 5 Ma. Uplift of the mountain blocks during this interval led to erosional stripping of the thick zones of weathered quartz-rich granitoid rocks to form etchplains dotted by bouldery tors—the iconic landscape of the Park. The stripped debris filled basins along the fault zones.Mountain ranges

Vertical slab sinking and westward subduction offshore of Mesozoic North America

Science.gov (United States)

Sigloch, Karin; Mihalynuk, Mitchell G.

2013-04-01

Subducted slabs in the mantle, as imaged by seismic tomography, preserve a record of ancient subduction zones. Ongoing debate concerns how direct this link is. How long ago did each parcel of slab subduct, and where was the trench located relative to the imaged slab position? Resolving these questions will benefit paleogeographic reconstructions, and restrict the range of plausible rheologies for mantle convection simulations. We investigate one of the largest and best-constrained Mesozoic slab complexes, the "Farallon" in the transition zone and lower mantle beneath North America. We quantitatively integrate observations from whole-mantle P-wave tomography, global plate reconstructions, and land geological evidence from the North American Cordillera. These three data sets permit us to test the simplest conceivable hypothesis for linking slabs to paleo-trenches: that each parcel of slab sank only vertically shortly after entering the trench That is, we test whether within the limits of tomographic resolution, all slab material lies directly below the location where it subducted beneath its corresponding arc. Crucially and in contrast to previous studies, we do not accept or impose an Andean-style west coast trench (Farallon-beneath-continent subduction) since Jurassic times, as this scenario is inconsistent with many geological observations. Slab geometry alone suggests that trenches started out as intra-oceanic because tomography images massive, linear slab "walls" in the lower mantle, extending almost vertically from about 800 km to 2000+ km depth. Such steep geometries would be expected from slabs sinking vertically beneath trenches that were quasi-stationary over many tens of millions of years. Intra-oceanic trenches west of Mesozoic North America could have been stationary, whereas a coastal Farallon trench could not, because the continent moved westward continuously as the Atlantic opened. Overlap of North American west-coast positions, as reconstructed in a

Geological evolution and uranium mineralisation of Chhinjra area, Kulu district, Himachal Pradesh

Energy Technology Data Exchange (ETDEWEB)

Sen, D B; Kumar, Suresh; Gangadharan, G R [Department of Atomic Energy, New Delhi (India). Atomic Minerals Div.

1995-08-01

Several shear-controlled and fracture-filled/disseminated type uranium occurrences are known in the Rampur window. This paper presents the geology and genetic aspects of fracture-filled type of mineralisation in Chhinjra area on the basis of recent stratigraphical, geochronological and tectonic data. Based on the angular unconformity between Manikaran quartzites and overlying chlorite phyllites, the geological evolution of Chhinjra area has been reconstructed in two stages: pre-unconformity and post-unconformity. Each stage is characterised by different phases of deformation with typical structural style and accompanying mineralisation processes. Four major tectonic events can be recognised here, namely 2500 Ma, 1200 Ma, 700 Ma and 55 Ma. Each event has left its imprint on the rocks as well as uranium mineralisation of Chhinjra area. (author). 14 refs., 4 figs.

Petroleum and natural gas geology and plate tectonics

Energy Technology Data Exchange (ETDEWEB)

Koebel, B.

1984-01-01

Several processes of oil and gas geology are studied in connection with plate-tectonical processes. Thus it becomes clear, that there is a distinct difference between the Paleozoic development of the European plate and the Mesozoic development. One can state, that the Paleozoic development is essentially influenced by the positions of the mobile belts and the cratonized parts of the plates. The development during Meso-Caenozoic is mainly characterized by crustal processes in the result of the disintegration of Pangaea.

Long-term evolution of the Campine area in Northern Belgium: past and expected future evolution of tectonics and climate

International Nuclear Information System (INIS)

De Craen, M.; Beerten, K.; Brassinnes, S.; Wouters, L.

2012-01-01

Document available in extended abstract form only. Disposal of radioactive waste in a geological repository involves the reliance, now and in the long-term future, on the geological and hydrogeological environment. In preparation of the safety and feasibility case 1 (SFC1), the long-term geodynamic evolution of Boom Clay and its geological environment in the Campine area in northern Belgium is studied. Time frames considered are the geological past and the future 1 million year. The idea is that the past long-term evolution can be extended to predict what might happen in the future. In this paper, we first focusses on the past long-term tectonic evolution of the Campine area, and make an extrapolation for the future 1 Ma. We then focus on past climate evolution, and similarly, an assessment of possible future climate conditions is made for the Campine area within the next 1 Ma. Another paper focusses on the combined effect of tectonics and climate on the evolution of the surface environment in the Campine area for the next 1 Ma, with respect to geomorphological, pedological and hydrological processes. During the Palaeozoic, the geodynamic evolution of the Campine area was mainly determined by tectonics. A large intermittently subsiding sedimentary basin existed in which large amounts of sediments were deposited, and which was protected by the Brabant Massif from major oro-genetic compressive processes. Palaeozoic sediments in the Campine Basin reach a maximum thickness of 4000 m. During Mesozoic and Cenozoic, its geodynamic evolution was the interactive result of plate tectonics, sea level changes and climate evolution. Further subsidence resulted in a thick sequence of sedimentary deposits. Mesozoic sediments are found throughout the Campine area while remains of Jurassic-Triassic sediments are found only in the central Roer Valley Graben in the east. The Cenozoic is characterised by a succession of sub-horizontal layers of Tertiary clays and sands and covered by

Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils

OpenAIRE

Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Rieppel, Olivier; Chen, Guan-bao

2014-01-01

Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exc...

An integrated geophysical study on the Mesozoic strata distribution and hydrocarbon potential in the South China Sea

Science.gov (United States)

Hu, Weijian; Hao, Tianyao; Jiang, Weiwei; Xu, Ya; Zhao, Baimin; Jiang, Didi

2015-11-01

A series of drilling, dredge, and seismic investigations indicate that Mesozoic sediments exist in the South China Sea (SCS) which shows a bright prospect for oil and gas exploration. In order to study the distribution of Mesozoic strata and their residual thicknesses in the SCS, we carried out an integrated geophysical study based mainly on gravity data, gravity basement depth and distribution of residual Mesozoic thickness in the SCS were obtained using gravity inversion constrained with high-precision drilling and seismic data. In addition, the fine deep crustal structures and distribution characteristics of Mesozoic thicknesses of three typical profiles were obtained by gravity fitting inversion. Mesozoic strata in the SCS are mainly distributed in the south and north continental margins, and have been reformed by the later tectonic activities. They extend in NE-trending stripes are macro-controlled by the deep and large NE-trending faults, and cut by the NW-trending faults which were active in later times. The offset in NW direction of Mesozoic strata in Nansha area of the southern margin are more obvious as compared to the north margin. In the Pearl River Mouth Basin and Southwest Taiwan Basin of the north continental margin the Mesozoic sediments are continuously distributed with a relatively large thickness. In the Nansha area of the south margin the Mesozoic strata are discontinuous and their thicknesses vary considerably. According to the characteristics of Mesozoic thickness distribution and hydrocarbon potential analyses from drilling and other data, Dongsha Uplift-Chaoshan Depression, Southwest Taiwan Basin-Peikang Uplift and Liyue Bank have large thickness of the Mesozoic residual strata, have good hydrocarbon genesis capability and complete source-reservoir-cap combinations, show a bright prospect of Mesozoic oil/gas resources.

Geology of Northwestern Switzerland - with special emphasis on Opalinus Clay

International Nuclear Information System (INIS)

Burkhard, M.

2007-01-01

This report describes the variations of the geological structures of Northwestern Switzerland during about the last 200 million years. This gives an explanation for the present partition of the different rock layers in the studied domain. The geology of Switzerland is dominated by the formation of the Alps. The Mont Terri geology is best explained within the framework of the tectonic Wilson cycle: assembly of Pangea in Late Paleozoic times culminating in the Variscan orogeny, collapse and decay of this earlier mountain chain, peneplanation and new rifting leading to the opening of the alpine Tethys Ocean during the Mesozoic, followed by plate convergence, subduction, collision and new mountain-building in the Neogene. The Mont Terri geology bears witness to the same suite of events as the Alps; tectonically speaking, Mont Terri is part of the Alps. Africa continues to push Apulia against the larger European plate and the question arises as to what the geological future has in store for our hills and mountains. Recent GPS (Global Positioning System) data Iead to believe that it will be just erosion and decay

A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtles

Science.gov (United States)

2013-01-01

Background Most turtles from the Middle and Late Jurassic of Asia are referred to the newly defined clade Xinjiangchelyidae, a group of mostly shell-based, generalized, small to mid-sized aquatic froms that are widely considered to represent the stem lineage of Cryptodira. Xinjiangchelyids provide us with great insights into the plesiomorphic anatomy of crown-cryptodires, the most diverse group of living turtles, and they are particularly relevant for understanding the origin and early divergence of the primary clades of extant turtles. Results Exceptionally complete new xinjiangchelyid material from the ?Qigu Formation of the Turpan Basin (Xinjiang Autonomous Province, China) provides new insights into the anatomy of this group and is assigned to Xinjiangchelys wusu n. sp. A phylogenetic analysis places Xinjiangchelys wusu n. sp. in a monophyletic polytomy with other xinjiangchelyids, including Xinjiangchelys junggarensis, X. radiplicatoides, X. levensis and X. latiens. However, the analysis supports the unorthodox, though tentative placement of xinjiangchelyids and sinemydids outside of crown-group Testudines. A particularly interesting new observation is that the skull of this xinjiangchelyid retains such primitive features as a reduced interpterygoid vacuity and basipterygoid processes. Conclusions The homology of basipterygoid processes is confidently demonstrated based on a comprehensive review of the basicranial anatomy of Mesozoic turtles and a new nomenclatural system is introduced for the carotid canal system of turtles. The loss of the basipterygoid process and the bony enclosure of the carotid circulation system occurred a number of times independently during turtle evolution suggesting that the reinforcement of the basicranial region was essential for developing a rigid skull, thus paralleling the evolution of other amniote groups with massive skulls. PMID:24053145

A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtles.

Science.gov (United States)

Rabi, Márton; Zhou, Chang-Fu; Wings, Oliver; Ge, Sun; Joyce, Walter G

2013-09-22

Most turtles from the Middle and Late Jurassic of Asia are referred to the newly defined clade Xinjiangchelyidae, a group of mostly shell-based, generalized, small to mid-sized aquatic froms that are widely considered to represent the stem lineage of Cryptodira. Xinjiangchelyids provide us with great insights into the plesiomorphic anatomy of crown-cryptodires, the most diverse group of living turtles, and they are particularly relevant for understanding the origin and early divergence of the primary clades of extant turtles. Exceptionally complete new xinjiangchelyid material from the ?Qigu Formation of the Turpan Basin (Xinjiang Autonomous Province, China) provides new insights into the anatomy of this group and is assigned to Xinjiangchelys wusu n. sp. A phylogenetic analysis places Xinjiangchelys wusu n. sp. in a monophyletic polytomy with other xinjiangchelyids, including Xinjiangchelys junggarensis, X. radiplicatoides, X. levensis and X. latiens. However, the analysis supports the unorthodox, though tentative placement of xinjiangchelyids and sinemydids outside of crown-group Testudines. A particularly interesting new observation is that the skull of this xinjiangchelyid retains such primitive features as a reduced interpterygoid vacuity and basipterygoid processes. The homology of basipterygoid processes is confidently demonstrated based on a comprehensive review of the basicranial anatomy of Mesozoic turtles and a new nomenclatural system is introduced for the carotid canal system of turtles. The loss of the basipterygoid process and the bony enclosure of the carotid circulation system occurred a number of times independently during turtle evolution suggesting that the reinforcement of the basicranial region was essential for developing a rigid skull, thus paralleling the evolution of other amniote groups with massive skulls.

Geologic control on the evolution of the inner shelf morphology offshore of the Mississippi barrier islands, northern Gulf of Mexico, USA

Science.gov (United States)

Flocks, James G.; Kindinger, Jack G.; Kelso, Kyle W.

2015-01-01

Between 2008 and 2013, high-resolution geophysical surveys were conducted around the Mississippi barrier islands and offshore. The sonar surveys included swath and single-beam bathymetry, sidescan, and chirp subbottom data collection. The geophysical data were groundtruthed using vibracore sediment collection. The results provide insight into the evolution of the inner shelf and the relationship between the near surface geologic framework and the morphology of the coastal zone. This study focuses on the buried Pleistocene fluvial deposits and late Holocene shore-oblique sand ridges offshore of Petit Bois Island and Petit Bois Pass. Prior to this study, the physical characteristics, evolution, and interrelationship of the ridges between both the shelf geology and the adjacent barrier island platform had not been evaluated. Numerous studies elsewhere along the coastal margin attribute shoal origin and sand-ridge evolution to hydrodynamic processes in shallow water (<20 m). Here we characterize the correlation between the geologic framework and surface morphology and demonstrate that the underlying stratigraphy must also be considered when developing an evolutionary conceptual model. It is important to understand this near surface, nearshore dynamic in order to understand how the stratigraphy influences the long-term response of the coastal zone to sea-level rise. The study also contributes to a growing body of work characterizing shore-oblique sand ridges which, along with the related geology, are recognized as increasingly important components to a nearshore framework whose origins and evolution must be understood and inventoried to effectively manage the coastal zone.

Current perspectives on the evolution of birds

NARCIS (Netherlands)

Ericson, P.G.P.

2008-01-01

The paper summarizes the current understanding of the evolution and diversification of birds. New insights into this field have mainly come from two fundamentally different, but complementary sources of information: the many newly discovered Mesozoic bird fossils and the wealth of genetic analyses

Preliminary Geologic Map of the Little Piute Mountains, California; a Digital Database

Science.gov (United States)

Howard, Keith A.; Dennis, Michael L.; Karlstrom, Karl; Phelps, Geoffrey A.

1997-01-01

Introduction The Little Piute Mountains in the eastern Mojave Desert expose a series of folds and thrust faults involving metamorphosed Paleozoic strata (Miller and others, 1982; Stone and others, 1983). Detailed mapping of these structures was undertaken to help elucidate regional Mesozoic structural evolution. Earlier geologic maps were prepared by Cooksley (1960a,b,c,d, generalized by Bishop, 1964) and Stone and others (1983). Deformed and metamorphosed Paleozoic and Triassic rocks form a stratal succession that was originally deposited in shallow seas on the North American craton. Based on lithologic sequence the units are correlated with unmetamorphosed equivalents 200 km to the northeast in the Grand Canyon, Arizona, and 35-50 km to the west in the Marble, Ship, and Providence Mountains, California (Stone and others, 1983). The Paleozoic sequence rests nonconformably on a heterogeneous basement of polydeformed Early Proterozoic gneiss (Miller and others, 1982; Wooden and Miller, 1990). Triassic and older rocks were deformed, metamorphosed to staurolite or andalusite grade, and intruded concordantly at their base by Late Cretaceous granodiorite (Miller and others, 1982).

A state geological survey commitment to environmental geology - the Texas Bureau of Economic Geology

International Nuclear Information System (INIS)

Wermund, E.G.

1990-01-01

In several Texas environmental laws, the Bureau of Economic Geology is designated as a planning participant and review agency in the process of fulfilling environmental laws. Two examples are legislation on reclamation of surface mines and regulation of processing low level radioactive wastes. Also, the Bureau is the principal geological reviewer of all Environmental Assessments and Environmental Impact Statements which the Office of the Governor circulates for state review on all major developmental activities in Texas. The BEG continues its strong interest in environmental geology. In February 1988, it recommitted its Land Resources Laboratory, initiated in 1974, toward fulfilling needs of state, county, and city governments for consultation and research on environmental geologic problems. An editorial from another state geological survey would resemble the about description of texas work in environmental geology. State geological surveys have led federal agencies into many developments of environmental geology, complemented federal efforts in their evolution, and continued a strong commitment to the maintenance of a quality environment through innovative geologic studies

The Mesozoic rift basins of eastern North America: Potential reservoir or Explorationist's folly

Energy Technology Data Exchange (ETDEWEB)

Pyron, A.

1991-08-01

Mesozoic rift basins are found on the East Coast of North America from Georgia to Nova Scotia. The basins formed as a result of extensional activity associated with the breakup of Pangaea. The internal geometry of the basins includes a depositional sequence ranging from coarse fanglomerates to fine-grained siltstones and argillites. Since these Mesozoic rift basins were first studied, they have not been considered to be likely spots for hydrocarbon accumulations. Recently, geologists have reconsidered these Mesozoic basins and have developed a more synergistic approach that suggests that many of these rift basins might be suitable targets for exploration. By analogy, these Mesozoic basins are correlative to similar basins in northwestern Africa, where significant reserved of oil and natural gas have been developed. The similarity between the productive basins in northwestern Africa and the Mesozoic basins of North America and their proximity to major markets provides sufficient rationale to further investigate these basins.

Mesozoic lithofacies palaeogeography and petroleum prospectivity in North Carnarvon Basin, Australia

Directory of Open Access Journals (Sweden)

Tao Chongzhi

2013-01-01

Full Text Available The North Carnarvon Basin, which lies in the North West Shelf of Australia, is highly rich in gas resources. As a typical passive marginal basin, it experienced the pre-rifting, early rifting, main rifting, late rifting, post-rifting sagging and passive margin stages. The basin was mainly filled with thick Mesozoic-Cenozoic sediments, of which the Mesozoic hosts the principal source, reservoir and seal intervals. Mesozoic palaeogeography has an important control on the oil and gas distribution. Triassic gas-prone source rocks of deltaic origin determine the high endowment of natural gases in the North Carnarvon Basin. The more restricted distribution of oil accumulations is controlled by oil source rocks in the Upper Jurassic Dingo Claystone. The Muderong Shale deposited in the Early Cretaceous marine transgression provides the effective regional seal for the underlying oil and gas reservoirs.

Preliminary Geologic Map of the the Little Piute Mountains, San Bernardino County, California

Science.gov (United States)

Howard, Keith A.; Dennis, Michael L.; Karlstrom, Karl E.; Phelps, Geoffrey A.

1995-01-01

Introduction The Little Piute Mountains in the eastern Mojave Desert expose a series of folds and thrust faults involving metamorphosed Paleozoic strata (Miller and others, 1982; Stone and others, 1983). Detailed mapping of these structures was undertaken to help elucidate regional Mesozoic structural evolution. Earlier geologic maps were prepared by Cooksley (1960a,b,c,d, generalized by Bishop, 1964) and Stone and others (1983). Deformed and metamorphosed Paleozoic and Triassic rocks form a stratal succession that was originally deposited in shallow seas on the North American craton. Based on lithologic sequence the units are correlated with unmetamorphosed equivalents 200 km to the northeast in the Grand Canyon, Arizona, and 35-50 km to the west in the Marble, Ship, and Providence Mountains, California (Stone and others, 1983). The Paleozoic sequence rests nonconformably on a heterogeneous basement of polydeformed Early Proterozoic gneiss (Miller and others, 1982; Wooden and Miller, 1990). Triassic and older rocks were deformed, metamorphosed to staurolite or andalusite grade, and intruded concordantly at their base by Late Cretaceous granodiorite (Miller and others, 1982).

Post-Palaeozoic uplift history of southeastern Australia revisited: results from a process-based mode of landscape evolution

International Nuclear Information System (INIS)

Van Der Beek, P.A.; Braun, J.; Lambeck, K.

1999-01-01

Developments over the last decade in the debate concerning the geomorphic evolution of the south-eastern Australian highlands are reviewed, taking as a starting point the model of passive denudation and isostatic rebound of a Palaeozoic mountain belt presented by Lambeck and Stephenson (1986). This model has been popular in the geomorphological community because it provides a quantitative framework to explain the very low rates of landscape evolution inferred from most geomorphological studies. The model has, however, also been criticised for its treatment of erosion as being linearly dependent on elevation, as well as for its predictions of regional uplift and denudation patterns that are not in accord with inferences from fission-track thermochronological data. Part of controversy stems from conceptual misunderstandings on the interpretation of data and from insufficient consideration of questions of spatial and temporal scale. First results of a new physical process-based model for large-scale long-term landscape evolution in the south-eastern highlands are presented. These show that the denudation history and drainage development of south-eastern Australia can be explained to a first order without invoking large-scale mid-Cretaceous or Tertiary uplift events. The model predicts drainage patterns in southeastern Australia to have evolved by rearrangement of an initially north-westerly directed drainage net, caused by drops in base-level during Mesozoic rifting along the southern and eastern margins of the study region. The geomorphology and available fission-track data in the Snowy Mountains region (and possibly also in the Bathurst - Blue Mountains region) do require renewed (mid Cretaceous?) uplift to have taken place. The model results are discussed in the light of recent controversies surrounding the southeastern highlands-their uplift history, denudation rates, depth of denudation of the coastal strip and inferred Mesozoic drainage patterns. Copyright (1999

Pb, Sr and Nd isotope geological characteristics and its evolution of Jianchaling rock

International Nuclear Information System (INIS)

Pang Chunyong; Chen Minyang; Xu Wenxin

2003-01-01

It has been a long time debatable subject on the raw material source and its genesis of Jianchaling ultrabasic rock, because the original rock phases, the original mineral compositions, texture and structure, even part of the chemical components of the rocks had been changed completely after many periods and phases of metamorphism. According to the content of Pb, Rb, Sr, Nd elements and their Pb, Sr, Nd isotope compositions of the rocks, together with the isotope geological age of late magmatic activities, the authors analyze the evolution of Pb, Sr, Nd isotope compositions, The inferred initiate Nd isotope ratio of ultrabasic rocks is 0.510233, lower than that of meteorite unity at a corresponding period, its ε Nd(T)>O; The initiate Sr ratios inferred by the isotope geological age ranges from 0.702735 to 0.719028; Projecting the lead isotope compositions on the Pb tectonic evolution model, the result indicates that the raw material of Jianchaling ultrabasic rock coming from the deplete upper mantle. The ultrabasic magma which enrich of Mg, Ni and less S intruded the crust and formed the Jianchaling ultrabasic rock at late Proterozoic era (927 Ma±). The forming time of serpentinite is mostly equal to the granitoid intruding time, showing the intrusion o flate acidic magma caused a large scale alteration of the ultrabasic rocks and formed the meta-ultrabasic phase rock observed today. (authors)

Regional evolution of geological structure in south China and U mineralization

International Nuclear Information System (INIS)

Chen Guoda; Kang Zili; Shen Jinrui; Jin Yushu

1992-01-01

This paper states the development laws of regional geological structure of South China and its controlling effect on uranium deposit evolution, and the characteristics of rich uranium formation in different periods of geo-history are analysed. It also discusses the relationship between the distribution of time and space and tectonic structure and environmental vicissitudes. The rock-magma activities-the strong formation of the Diwa Era is of great significance to the formation of uranium deposits within the region, especially to the formation of a series of multi-genesis polygene uranium deposits which are a potential direction in which to look for minerals within the region

A preliminary study on the long-term geologic stability for deep geological disposal of high level radioactive waste in Korea

Energy Technology Data Exchange (ETDEWEB)

Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Park, Byoung Yoon; Koh, Young Kown [Korea Atomic Energy Research Institute, Taejeon (Korea)

2000-03-01

Geology of the Korean peninsula could be grouped by 7 rock types such as plutonic rocks, crystalline gneisses, metasedimentary rocks, Paleozoic and Mesozoic sedimentary rocks, porous and massive volcanic rocks. The plutonic rock type is the largest rock groups occupying about 35.2% over the peninsula. Tectonic movement could be classified as four great stages as Precambrian, Songnim, Daebo and Bulkuksa even though the ambiguous of prior Songnim. It would be supposed to deep relationship between tectonic movement, orogeny and magmatism. And also, the magmatism within the peninsula could be divided into 5 stages such as 1st stage of Precambrian(>570Ma), 2nd stage of late Paleozoic(>250Ma), 3rd stage of early to mid Mesozoic(200-300Ma), 4th stage of late Mesozoic(135-60Ma) and 5th stage of post early Tertiary(50Ma>). In the seismicities, the peninsula has some characteristics that of the intra-plate seismic characteristics located at south eastern part of the Eurasian plate apart from the boundary of the Pacific and Philippine plate. Eurasian plate is under the two stress direction acting eastward stresses induced the collision of Indo- Australlian plate and westward stresses due to the subduction of due the Pacific and Philippine plate. For the purpose of the quantitative analysis for the safety assessment of HLW disposal, it would be desired to have the long range approach concept for the characterization of FEPs such as upper stated including climate, sae level change, uplift and subsidence, erosion and sedimentation. 38 refs., 18 figs., 25 tabs. (Author)

Mesozoic anomalies in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Ramana, M.V.; Nair, R.R.; Sarma, K.V.L.N.S.; Ramprasad, T.; Krishna, K.S.; Subrahmanyam, V.; D; Subrahmanyam, C.; Paul, J.; Subrahmanyam, A.S.; Sekhar, D

. The configuration of the offsets of the isochrons allowed us to propose approximately N120~'E-trending oceanic fracture zones. The Mesozoic crust of 132.5-118 Ma is estimated to evolve with an average half-spreading rate of 3.5 cm/yr, except for the ocean floor...

The role of post-collisional strike-slip tectonics in the geological evolution of the late Neoproterozoic volcano-sedimentary Guaratubinha Basin, southern Brazil

Science.gov (United States)

Barão, Leonardo M.; Trzaskos, Barbara; Vesely, Fernando F.; de Castro, Luís Gustavo; Ferreira, Francisco J. F.; Vasconcellos, Eleonora M. G.; Barbosa, Tiago C.

2017-12-01

The Guaratubinha Basin is a late Neoproterozoic volcano-sedimentary basin included in the transitional-stage basins of the South American Platform. The aim of this study is to investigate its tectonic evolution through a detailed structural analysis based on remote sensing and field data. The structural and aerogeophysics data indicate that at least three major deformational events affected the basin. Event E1 caused the activation of the two main basin-bounding fault zones, the Guaratubinha Master Fault and the Guaricana Shear Zone. These structures, oriented N20-45E, are associated with well-defined right-lateral to oblique vertical faults, conjugate normal faults and vertical flow structures. Progressive transtensional deformation along the two main fault systems was the main mechanism for basin formation and the deposition of thick coarse-grained deposits close to basin-borders. The continuous opening of the basin provided intense intermediate and acid magmatism as well as deposition of volcaniclastic sediments. Event E2 characterizes generalized compression, recorded as minor thrust faults with tectonic transport toward the northwest and left-lateral activation of the NNE-SSW Palmital Shear Zone. Event E3 is related to the Mesozoic tectonism associated with the South Atlantic opening, which generated diabase dykes and predominantly right-lateral strike-slip faults oriented N10-50W. Its rhomboidal geometry with long axis parallel to major Precambrian shear zones, the main presence of high-angle, strike-slip or oblique faults, the asymmetric distribution of geological units and field evidence for concomitant Neoproterozoic magmatism and strike-slip movements are consistent with pull-apart basins reported in the literature.

Geology of Uruguay review

International Nuclear Information System (INIS)

Gomez Rifas, C.

2011-01-01

This work is about the Uruguay geology review.This country has been a devoted to breeding cattle and agriculture.The evolution of geological knowledge begun with Dr. Karl Walther who published 53 papers between 1909 and 1948.

The Interior and Orbital Evolution of Charon as Preserved in Its Geologic Record

Science.gov (United States)

Rhoden, Alyssa Rose; Henning, Wade; Hurford, Terry A.; Hamilton, Douglas P.

2014-01-01

Pluto and its largest satellite, Charon, currently orbit in a mutually synchronous state; both bodies continuously show the same face to one another. This orbital configuration is a natural end-state for bodies that have undergone tidal dissipation. In order to achieve this state, both bodies would have experienced tidal heating and stress, with the extent of tidal activity controlled by the orbital evolution of Pluto and Charon and by the interior structure and rheology of each body. As the secondary, Charon would have experienced a larger tidal response than Pluto, which may have manifested as observable tectonism. Unfortunately, there are few constraints on the interiors of Pluto and Charon. In addition, the pathway by which Charon came to occupy its present orbital state is uncertain. If Charon's orbit experienced a high-eccentricity phase, as suggested by some orbital evolution models, tidal effects would have likely been more significant. Therefore, we determine the conditions under which Charon could have experienced tidally-driven geologic activity and the extent to which upcoming New Horizons spacecraft observations could be used to constrain Charon's internal structure and orbital evolution. Using plausible interior structure models that include an ocean layer, we find that tidally-driven tensile fractures would likely have formed on Charon if its eccentricity were on the order of 0.01, especially if Charon were orbiting closer to Pluto than at present. Such fractures could display a variety of azimuths near the equator and near the poles, with the range of azimuths in a given region dependent on longitude; east-west-trending fractures should dominate at mid-latitudes. The fracture patterns we predict indicate that Charon's surface geology could provide constraints on the thickness and viscosity of Charon's ice shell at the time of fracture formation.

The relational of Mesozoic volcanism to uranium mineralization in Guyuan-Hongshanzi area

International Nuclear Information System (INIS)

Wu Rengui; Xu Zhe; Yu Zhenqing; Jiang Shan; Shen Kefeng

2011-01-01

Based on the time of Mesozoic volcanism,the characteristic of major and trace element, and REE pattern of the volcanic rocks in Guyuan-Hongshanzi area, The Mesozoic volcanism can be divided into the early cycle and later cycle during the Early Cretaceous, and it's magma series is classified in two sub-series, one is alkaline series of trachyte dominated and another is subalkaline series of rhyolite dominated. The relations between Mesozoic volcanism and uranium mineralization is mainly shown in four aspects: (1) Uranium mineralization controlled by the coexist of two magma series; (2) Uranium mineralization controlled by superhypabyssal porphyry body in later cycle volcanism during the Early Cretaceous; (3) The porphyry body close to uranium mineralization,bearing the genesis characteristics of crust-mantle action; and (4) High Si and K content in the chemical composition of the mineralization volcanic rocks. (authors)

The geology and hydrocarbon possibilities of the Triassic-Jurassic Fundy Basin, eastern Canada

Energy Technology Data Exchange (ETDEWEB)

Wade, J.A.; Fensome, R.A. [Geological Survey of Canada, Dartmouth, NS (Canada). Atlantic Geoscience Centre; Brown, D.E. [Canada-Nova Scotia Offshore Petroleum Board, Halifax, NS (Canada)

1997-09-01

The development of the Mesozoic sedimentary basins beneath the waters of the eastern coast of North America was discussed. These basins have been linked to the rifting of the central part of Pangaea during Mid and Late Triassic time that ended in the formation of a series of grabens extending from Florida to The Grand Banks of Newfoundland, one of them being the Bay of Fundy Basin which is about 16,500 square kilometres in size. Onshore and offshore geologic mapping and seismic interpretations have shown their age range to be from the Mid Triassic Anisian or Ladinian to Mid Jurassic. Up to 12 km of Mesozoic rocks were deposited in the basin with up to 9 km still present. The depositional history of the area was described. The two areas with greatest hydrocarbon potential are the Bay of Fundy and the Chignecto subbasins.

Geological and thermal exploration for an evaluation of the geothermal potential of Luxembourg

Science.gov (United States)

Schintgen, Tom; Förster, Andrea

2013-04-01

In 2010, work has commenced on the evaluation of the geothermal potential of Luxembourg. The concept of this evaluation comprises several steps. Given the limited amount of geological data and the lack of petrothermal data as well as on crustal heat flow, in-depth studies are needed that allow a comprehensive insight into the shallow as well as deep thermal subsurface structure and thus to make temperature prognoses for the use of geothermal energy. Here we report the geological structure of the Mesozoic Trier-Luxembourg Basin (TLB) with its various lithological units as well as the geology of the underlying basement units. The thickness of the Mesozoic section increases from 400-500 m in the northeastern part of the basin to a maximum of 1100 m in the southern part of Luxembourg. New data on thermal parameters, such as the thermal conductivity (TC), radiogenic heat production (RHP) and porosity are presented for the major lithotypes of the TLB as well as of the underlying Paleozoic basement. These data originated from core samples (Mesozoic formations) and from sampling of outcrops of Luxembourg's surroundings (Paleozoic formations). Thus data are now available for an up to 13-km-thick succession of the upper crust, comprising the Lower Cambrian to the Middle Ordovician, the relatively thick Lower Devonian and the Triassic to Liassic of the TLB. For the remainder of the crust down to the Moho thermal properties are determined by translating seismic velocities into rock types and using average values for TC and RHP for these metamorphic and igneous rocks. Based on the new values of TC and a temperature log measured under thermal equilibrium in a 300-m deep borehole, surface heat flow was determined. These data form the basis for modeling the subsurface temperatures along two regional crustal cross sections, which cover most of the Rhenohercynian Zone of the Variscan orogenic belt. They extend from the Lower Paleozoic Stavelot Massif in the Belgian Ardennes in the

Geology and Geochemistry of Magmatic Rocks from the Southern Part of the Kyushu-Palau Ridge in the Philippine Sea

Science.gov (United States)

Lelikov, E. P.; Sedin, V. T.; Pugachev, A. A.

2018-03-01

The paper reports the results of a geochemical study of volcanogenic rocks from the southern part of the Kyushu-Palau Ridge. Volcanic structures, such as plateaulike rises, mountain massifs, and single volcanoes, are the major relief-forming elements of the southern part of the Kyushu-Palau Ridge. They are divided into three types according to the features of the relief and geological structure: shield, cone-shaped, and dome-shaped volcanoes. The ridge was formed on oceanic crust in the Late Mesozoic and underwent several stages of evolution with different significance and application of forces (tension and compression). Change in the geodynamic conditions during the geological evolution of the ridge mostly determined the composition of volcanic rocks of deep-mantle nature. Most of the ridge was formed by the Early Paleogene under geodynamic conditions close to the formation of oceanic islands (shield volcanoes) under tension. The island arc formed on the oceanic basement in the compression mode in the Late Eocene-Early Oligocene. Dome-shaped volcanic edifices composed of alkaline volcanic rocks were formed in the Late Oligocene-Early Miocene under tension. Based on the new geochemical data, detailed characteristics of volcanic rocks making up the shield, cone-shape, and dome-shape stratovolcanoes resulting in the features of these volcanic edifices are given for the first time. Continuous volcanism (with an age from the Cretaceous to the Late Miocene and composition from oceanic tholeiite to calc-alkaline volcanites of the island arc type) resulting in growth of the Earth's crust beneath the Kyushu-Palau Ridge was the major factor in the formation this ridge.

Mineral Grains, Dimples, and Hot Volcanic Organic Streams: Dynamic Geological Backstage of Macromolecular Evolution.

Science.gov (United States)

Skoblikow, Nikolai E; Zimin, Andrei A

2018-04-01

The hypothesis of hot volcanic organic stream as the most probable and geologically plausible environment for abiogenic polycondensation is proposed. The primary synthesis of organic compounds is considered as result of an explosive volcanic (perhaps, meteorite-induced) eruption. The eruption was accompanied by a shock wave propagating in the primeval atmosphere and resulting in the formation of hot cloud of simple organic compounds-aldehydes, alcohols, amines, amino alcohols, nitriles, and amino acids-products, which are usually obtained under the artificial conditions in the spark-discharge experiments. The subsequent cooling of the organic cloud resulted in a gradual condensation and a serial precipitation of organic compounds (in order of decreasing boiling point values) into the liquid phase forming a hot, viscous and muddy organic stream (named "lithorheos"). That stream-even if the time of its existence was short-is considered here as a geologically plausible environment for abiogenic polycondensation. The substances successively prevailing in such a stream were cyanamide, acetamide, formamide, glycolonitrile, acetonitrile. An important role was played by mineral (especially, phosphate-containing) grains (named "lithosomes"), whose surface was modified with heterocyclic nitrogen compounds synthesized in the course of eruption. When such grains got into hot organic streams, their surface catalytic centers (named "lithozymes") played a decisive role in the emergence, facilitation and maintenance of prebiotic reactions and key processes characteristic of living systems. Owing to its cascade structure, the stream was a factor underlying the formation of mineral-polymeric aggregates (named "lithocytes") in the small natural streambed cavities (dimples)-as well as a factor of their further spread within larger geological locations which played a role of chemo-ecological niches. All three main stages of prebiotic evolution (primary organic synthesis

Competition and constraint drove Cope's rule in the evolution of giant flying reptiles.

Science.gov (United States)

Benson, Roger B J; Frigot, Rachel A; Goswami, Anjali; Andres, Brian; Butler, Richard J

2014-04-02

The pterosaurs, Mesozoic flying reptiles, attained wingspans of more than 10 m that greatly exceed the largest birds and challenge our understanding of size limits in flying animals. Pterosaurs have been used to illustrate Cope's rule, the influential generalization that evolutionary lineages trend to increasingly large body sizes. However, unambiguous examples of Cope's rule operating on extended timescales in large clades remain elusive, and the phylogenetic pattern and possible drivers of pterosaur gigantism are uncertain. Here we show 70 million years of highly constrained early evolution, followed by almost 80 million years of sustained, multi-lineage body size increases in pterosaurs. These results are supported by maximum-likelihood modelling of a comprehensive new pterosaur data set. The transition between these macroevolutionary regimes is coincident with the Early Cretaceous adaptive radiation of birds, supporting controversial hypotheses of bird-pterosaur competition, and suggesting that evolutionary competition can act as a macroevolutionary driver on extended geological timescales.

Geological Structure and Radon Hazards in Lublin Region

Directory of Open Access Journals (Sweden)

Lucjan Gazda

2018-03-01

Full Text Available The purpose of the study was to show the relationship between the geological structure of the Lublin region (eastern Poland and radon concentrations in the ground air, and therefore, in the indoor environment of buildings located in that area. The study was based on the information pertaining to the geological structure of Lublin region available in the literature. The radon concentrations in buildings, caves, wells, as well as coal, phosphate and chalk mines were measured with both passive and active methods. Elemental analyses and uranium and lead isotope analyses of ground rocks were also performed. The conducted studies indicated that the sources of radon in Lublin region constitute Paleogene and Mesozoic sedimentary rocks rich in radionuclides. Application of radon remediation methods is recommended in the existing buildings located in the vicinity of these rocks, which are characterized by relatively high radon exhalations. On the other hand, the designed buildings should employ the measures protecting against harmful effects of radon presence.

Testing the Mojave-Sonora megashear hypothesis: Evidence from Paleoproterozoic igneous rocks and deformed Mesozoic strata in Sonora, Mexico

Science.gov (United States)

Amato, J.M.; Lawton, T.F.; Mauel, D.J.; Leggett, W.J.; Gonzalez-Leon, C. M.; Farmer, G.L.; Wooden, J.L.

2009-01-01

U-Pb ages and Nd isotope values of Proterozoic rocks in Sonora, Mexico, indicate the presence of Caborca-type basement, predicted to lie only south of the Mojave-Sonora mega-shear, 40 km north of the postulated megashear. Granitoids have U-Pb zircon ages of 1763-1737 Ma and 1076 Ma, with ??Nd(t) values from +1.4 to -4.3, typical of the Caborca block. Lower Jurassic strata near the Proterozoic rocks contain large granitic clasts with U-Pb ages and ??Nd(t) values indistinguishable from those of Caborcan basement. Caborca-type basement was thus present at this location north of the megashear by 190 Ma, the depositional age of the Jurassic strata. The Proterozoic rocks are interpreted as parautochthonous, exhumed and juxtaposed against the Mesozoic section by a reverse fault that formed a footwall shortcut across a Jurassic normal fault. Geochronology, isotope geochemistry, and structural geology are therefore inconsistent with Late Jurassic megashear displacement and require either that no major transcurrent structure is present in Sonora or that strike-slip displacement occurred prior to Early Jurassic time. ?? 2009 The Geological Society of America.

Evolution of Lower Brachyceran Flies (Diptera and Their Adaptive Radiation with Angiosperms

Directory of Open Access Journals (Sweden)

Bo Wang

2017-04-01

Full Text Available The Diptera (true flies is one of the most species-abundant orders of Insecta, and it is also among the most important flower-visiting insects. Dipteran fossils are abundant in the Mesozoic, especially in the Late Jurassic and Early Cretaceous. Here, we review the fossil record and early evolution of some Mesozoic lower brachyceran flies together with new records in Burmese amber, including Tabanidae, Nemestrinidae, Bombyliidae, Eremochaetidae, and Zhangsolvidae. The fossil records reveal that some flower-visiting groups had diversified during the mid-Cretaceous, consistent with the rise of angiosperms to widespread floristic dominance. These brachyceran groups played an important role in the origin of co-evolutionary relationships with basal angiosperms. Moreover, the rise of angiosperms not only improved the diversity of flower-visiting flies, but also advanced the turnover and evolution of other specialized flies.

3. South American symposium on isotope geology. Extended abstracts

International Nuclear Information System (INIS)

2001-10-01

This publication include papers in the fields on Methodology, thermochronology, and geochronology; Evolution of cratonic South America; Magmatic processes; Environmental geology, hydrogeology, isotopic stratigraphy and paleoclimatology; Economic Geology and Evolution of the Andean margin of South America

Mesozoic mammals from Arizona: new evidence on Mammalian evolution.

Science.gov (United States)

Jenkins, F A; Crompton, A W; Downs, W R

1983-12-16

Knowledge of early mammalian evolution has been based on Old World Late Triassic-Early Jurassic faunas. The discovery of mammalian fossils of approximately equivalent age in the Kayenta Formation of northeastern Arizona gives evidence of greater diversity than known previously. A new taxon documents the development of an angular region of the jaw as a neomorphic process, and represents an intermediate stage in the origin of mammalian jaw musculature.

Mesozoic tectonics of the Otway Basin region: The legacy of Gondwana and the active Pacific margin: a review and ongoing research

Energy Technology Data Exchange (ETDEWEB)

Hill, K.A. [Monash Univ., Clayton, VIC (Australia). Department of Earth Sciences; Finlayson, D.M. [Australian Geological Survey Organisation, Canberra, ACT (Australia); Hill, K.C. [La Trobe Univ., Bundoora, VIC (Australia). School of Earth Sciences; Cooper, G.T. [Monash Univ., Clayton, VIC (Australia). Department of Earth Sciences

1995-12-31

Recent plate tectonic models for SE Australia and the formerly contiguous parts of Gondwana are reviewed in this paper in order to assess the Mesozoic evolution of the Otway Basin. Research around the Otway Basin is summarised to demonstrate how the application of new technology can address some of the outstanding questions regarding the Basin`s evolution on local to lithospheric scales. The geometry and geology of Australia`s southern margin are compared with Atlantic rift-drift margins to provide analogues for tectonics and hydrocarbon exploration in the Otway Basin. At least two stages of rifting were found to be evident in the Cretaceous and in the deep structure of the Otway basin. These are Early Cretaceous rifting which is manifested in numerous half-graben and accommodation zones, and Late Cretaceous rifting in the deep seismic data seaward of the Tartwaup, Timboon and Sorell fault zones. Major offsets of the spreading axis during break up, at the Tasman and Spencer Fracture Zones were probably controlled by the location of Paleozoic terrace boundaries. The Tasman Fracture System was reactivated during break-up, with considerable uplift and denudation of the Bass failed rift to the east, which controlled Otway Basin facies distribution. Paleozoic structures also had a significant effect in determining the half graben orientations within a general N-S extensional regime during early Cretaceous rifting. The late Cretaceous second stage of rifting, seaward of the Tartwaup, Timboon and Sorell fault zones, left stable failed rift margin to the north, but the attenuated lithosphere of the Otway-Sorell microplate to the south records repeated extension that led to continental separation and may be part of an Antarctic upper plate. 1 table. 16 figs., 4 photos., refs.

Mesozoic tectonomagmatic activity and uranium metallogenetic sequence in mid-Nanling tectonic belt

International Nuclear Information System (INIS)

Deng Ping; Shu Liangshu

2002-01-01

Based on the synthesis and analysis of the relationship of various Mesozoic intrusive massifs, the tectonic activity, and the hydrothermal veins, as well as data of isotopic geochronology, the author makes a time sequence of the tectonomagmatic activities, the hydrothermal activities and uranium mineralization, and summarizes characteristics of tectonomagmatic and hydrothermal activities of different stages, and discusses the time sequence of various ore-controlling factors for granite-type uranium metallogeny. Finally, authors conclude that uranium metallogeny shows a very close spatial and temporal relationship to Mesozoic tectonomagmatic and hydrothermal activities

Abundances of chemical elements in granitoids of different geological ages and their characteristics in China

Directory of Open Access Journals (Sweden)

Changyi Shi

2011-04-01

Full Text Available Actual granitoid analytical data of 767 composited samples are presented here. The data source is 6080 samples collected mainly from 750 large- to middle-sized granitoid bodies across China. Data from the composited samples, which includes that of 70 elements, is analyzed according to geological age — Archeozoic (Ar, Proterozoic (Pt, Eopaleozoic (Pz1, Neopaleozoic (Pz2, Mesozoic (Mz, and Cenozoic (Cz — and three major compositional varieties, e.g. alkali-feldspar granite, syenogranite and adamellite. Petrochemical parameters, trace-element content and rare-earth element (REE distributions of the different rock types and geological ages are characterized, and change tendencies through Archean to Cenozoic time are recorded. The comprehensive analytical data presented here has not been previously published. This significant data set can be used as fundamental information in studies of basic China geology, magma petrogenesis, ore exploration and geochemistry.

THE TECTONICS STRESS AND STRAIN FIELD MODELING ADJUSTED FOR EVOLUTION OF GEOLOGICAL STRUCTURES (SAILAG INTRUSION, EASTERN SAYAN

Directory of Open Access Journals (Sweden)

V. N. Voytenko

2013-01-01

Full Text Available The article describes a tectonophysical model showing evolution of structures in the Sailag granodiorite massif in relation to its gold-bearing capacity. The model takes into account the load patterns according to geological data, accumulated deformation, and gravity stresses. This model provides for updating the structural-geological model showing development of the intrusion body and the ore field. Forecasted are destruction patterns in the apical and above-dome parts of the massif  in the intrusion and contraction phase, formation of the long-term shear zone at the steeply dipping slope of the intrusion body, and subvertical fractures associated with the long-term shear zone and vertical mechanical ‘layering’ of the intrusive body.  

Geologic reconnaissance of the Hot Springs Mountains, Churchill County, Nevada

Science.gov (United States)

Voegtly, Nickolas E.

1981-01-01

A geologic reconnaissance of the Hot Springs Mountains and adjacent areas, which include parts of the Brady-Hazen and the Stillwater-Soda Lake Known Geothermal Resource Areas, during June-December 1975, resulted in a reinterpretation of the nature and location of some Basin and Range faults. In addition, the late Cenozoic stratigraphy has been modified, chiefly on the basis of radiometric dates of volcanic rocks by U.S. Geological Survey personnel and others. The Hot Springs Mountains are in the western part of the Basin and Range province, which is characterized by east-west crustal extension and associated normal faulting. In the surrounding Trinity, West Humboldt, Stillwater, and Desert Mountains, Cenozoic rocks overlie ' basement ' rocks of the Paleozoic and Mesozoic age. A similar relation is inferred in the Hot Springs Mountains. Folding and faulting have taken place from the late Tertiary to the present. (USGS)

UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

Energy Technology Data Exchange (ETDEWEB)

Rugheimer, S.; Sasselov, D. [Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge (United States); Segura, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México (Mexico); Kaltenegger, L., E-mail: srugheimer@cfa.harvard.edu [Carl Sagan Institute, Cornell University, Ithaca, NY 14853 (United States)

2015-06-10

The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

International Nuclear Information System (INIS)

Rugheimer, S.; Sasselov, D.; Segura, A.; Kaltenegger, L.

2015-01-01

The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments

Late Cretaceous tectonothermal evolution of the southern Lhasa terrane, South Tibet: Consequence of a Mesozoic Andean-type orogeny

Science.gov (United States)

Dong, Xin; Zhang, Ze-ming; Klemd, Reiner; He, Zhen-yu; Tian, Zuo-lin

2018-04-01

The Lhasa terrane of the southern Tibetan Plateau participated in a Mesozoic Andean-type orogeny caused by the northward subduction of the Neo-Tethyan oceanic lithosphere. However, metamorphic rocks, which can unravel details of the geodynamic evolution, are rare and only exposed in the south-eastern part of the Lhasa terrane. Therefore, we conducted a detailed petrological, geochemical and U-Pb zircon geochronological study of the late Cretaceous metamorphic rocks and associated gabbros from the Nyemo inlier of the southern Lhasa terrane. The Nyemo metamorphic rocks including gneisses, schists, marbles and calc-silicate rocks, experienced peak amphibolite-facies contact metamorphism under P-T conditions of 3.5-4.0 kbar and 642-657 °C with a very high geothermal gradient of 45-50 °C/km, revealing a distinct deflection from the steady-state geotherm during low-pressure metamorphism. Inherited magmatic zircon cores from the metamorphic rocks yielded protolith ages of 197-194 Ma, while overgrowth zircon rims yielded metamorphic ages of ca. 86 Ma. Whole-rock chemistry and zircon Hf isotopes suggest that the protoliths of the gneisses and schists are andesites and tuffs of the early Jurassic Sangri Group, which were derived from a depleted mantle source of a continental arc affinity. The coeval intimately-associated gabbro (ca. 86 Ma) crystallized under P-T conditions of 3.5-5.3 kbar and 914-970 °C, supplying the heat flux high enough to cause the contact metamorphism of the Sangri Group rock types. We propose that the intrusion of the gabbro and a simultaneous pressure increase of up to 4.0 kbar, which is related to crustal thickening due to crustal overthrusting and the intrusion of mafic material, resulted in the late Cretaceous metamorphism of the early Jurassic Sangri Group during an Andean-type orogeny. Furthermore the Nyemo metamorphic rocks, which have previously been considered to represent slivers of the Precambrian metamorphic basement of the Lhasa terrane

Waste isolation in geologic formations in the USA

International Nuclear Information System (INIS)

Zerby, C.D.; McClain, W.C.

1976-01-01

The ERDA program for the establishment of terminal storage facilities for commercial radioactive wastes in deep geologic formations was recently reorganized as the National Waste Terminal Storage (NWTS) program. General plans for implementing this expanded program call for geologic investigations and feasibility confirmation studies at multiple geographic locations, leading to pilot plant construction and operation with possible future conversion into a Federal Repository. The pilot plant operations will be experimental facilities having limited capacity to store actual waste in a readily retrievable configuration. The first two pilot plants are planned to start operations simultaneously in the mid-1980's. Geologic investigations are now in progress or planned in study areas of the interior basins of the Gulf Coast Salt Dome Province, in the Salina Salt basin and in the Paradox Basin in an effort to identify acceptable locations for these initial facilities. Subsequent pilot plants will be located in other formations. Preliminary geologic evaluations have been initiated in the Paleozoic shales and limestones, Triassic shale basins along the east coast, Mesozoic shales of the Gulf Coast and northern high plains and certain crystalline igneous rocks. Most of the required engineering testing of disposal in salt formations has been completed in previous programs. However, the establishment of pilot plants in the other rock types will require a sequence of in situ testing designed to develop the information necessary to both demonstrate the feasibility of waste disposal in that particular formation and provide the data for facility designs

Post-Mesozoic Rapid Increase of Seawater Mg/Ca due to Enhanced Mantle-Seawater Interaction

Science.gov (United States)

Ligi, Marco; Bonatti, Enrico; Cuffaro, Marco; Brunelli, Daniele

2013-01-01

The seawater Mg/Ca ratio increased significantly from ~ 80 Ma to present, as suggested by studies of carbonate veins in oceanic basalts and of fluid inclusions in halite. We show here that reactions of mantle-derived peridotites with seawater along slow spreading mid-ocean ridges contributed to the post-Cretaceous Mg/Ca increase. These reactions can release to modern seawater up to 20% of the yearly Mg river input. However, no significant peridotite-seawater interaction and Mg-release to the ocean occur in fast spreading, East Pacific Rise-type ridges. The Mesozoic Pangean superocean implies a hot fast spreading ridge system. This prevented peridotite-seawater interaction and Mg release to the Mesozoic ocean, but favored hydrothermal Mg capture and Ca release by the basaltic crust, resulting in a low seawater Mg/Ca ratio. Continent dispersal and development of slow spreading ridges allowed Mg release to the ocean by peridotite-seawater reactions, contributing to the increase of the Mg/Ca ratio of post-Mesozoic seawater. PMID:24067442

Stratigraphy and geologic history of Mercury

International Nuclear Information System (INIS)

Spudis, P.D.; Guest, J.E.

1988-01-01

The geologic evolution of Mercury based on the Mariner-10 mission data is discussed. As reconstructed through photogeological analysis of global geologic relations of rock-stratigraphic units, Mercury's geologic history is shown to involve intensive early impact bombardment and widespread resurfacing by volcanic lavas. Evidence is presented to indicate that this volcanic activity essentially ended as much as 3 Gyr ago, with most of the major geologic events being completed within the first 1 to 1.5 Gyr of Mercurian history

Stratigraphy and geologic history of Mercury

Science.gov (United States)

Spudis, Paul D.; Guest, John E.

1988-01-01

The geologic evolution of Mercury based on the Mariner-10 mission data is discussed. As reconstructed through photogeological analysis of global geologic relations of rock-stratigraphic units, Mercury's geologic history is shown to involve intensive early impact bombardment and widespread resurfacing by volcanic lavas. Evidence is presented to indicate that this volcanic activity essentially ended as much as 3 Gyr ago, with most of the major geologic events being completed within the first 1 to 1.5 Gyr of Mercurian history.

Petroleum geology framework, southeast Bowser Basin, British Columbia

Energy Technology Data Exchange (ETDEWEB)

Haggart, J.W. [Geological Survey of Canada, Vancouver, BC (Canada); Mahoney, J.B. [Wisconsin Univ., Eau Claire, WS (United States). Dept. of Geology

2003-07-01

There are significant coal resources in the northern regions of the Bowser basin in north-central British Columbia. However, the resource potential of the southern part of the basin has not been assessed, therefore the hydrocarbon potential is not known. Geological maps indicate several Mesozoic clastic and volcanic units across the southern part of the basin. Two stratigraphic intervals of the southern Bowser basin are considered to be potential source rocks within the Jurassic-Cretaceous strata. The fine-grained clastic rocks of the Bowser Lake Group contain significant amounts of carbonaceous material or organic matter. Well developed cleavage indicates that the rocks may be thermally over mature. This paper described potential reservoir rocks within the basin, along with their thermal maturation and conceptual play. 4 figs.

Petrogenesis of late Paleozoic-to-early Mesozoic granitoids and metagabbroic rocks of the Tengchong Block, SW China: implications for the evolution of the eastern Paleo-Tethys

Science.gov (United States)

Zhu, Ren-Zhi; Lai, Shao-Cong; Qin, Jiang-Feng; Zhao, Shao-Wei

2018-03-01

This paper presents precise zircon U-Pb, bulk-rock geochemical, and Sr-Nd-Pb isotopic data for metagabbro, quartz diorite, and granite units within the Tengchong Block of SW China, which forms the southeastern extension of the Himalayan orogeny and the southwestern section of the Sanjiang orogenic belt, a key region for furthering our understanding of the evolution of the eastern Paleo-Tethys. These data reveal four groups of zircon U-Pb ages that range from the late Paleozoic to the early Mesozoic, including a 263.6 ± 3.6 Ma quartz diorite, a 218.5 ± 5.4 Ma two-mica granite, a 205.7 ± 3.1 Ma metagabbroic unit, and a 195.5 ± 2.2 Ma biotite granite. The quartz diorite in this area contains low concentrations of SiO2 (60.71-64.32 wt%), is sodium-rich, and is metaluminous, indicating formation from magmas generated by a mixed source of metamafic rocks with a significant metapelitic sedimentary material within lower arc crust. The two-mica granites contain high concentrations of SiO2 (73.2-74.3 wt%), are strongly peraluminous, and have evolved Sr-Nd-Pb isotopic compositions, all of which are indicative of a crustal source, most probably from the partial melting of felsic pelite and metagreywacke/psammite material. The metagabbros contain low concentrations of SiO2 (50.17-50.96 wt%), are sodium-rich, contain high concentrations of Fe2O3T (9.79-10.06 wt%) and CaO (6.88-7.12 wt%), and are significantly enriched in the Sr (869-894 ppm) and LREE (198.14-464.60 ppm), indicative of derivation from magmas generated by a metasomatized mantle wedge modified by the sedimentary-derived component. The biotite granites are weakly peraluminous and formed from magmas generated by melting of metasedimentary sources dominated by metagreywacke/psammite material. Combining the petrology and geochemistry of these units with the regional geology of the Indosinian orogenic belt provides evidence for two stages of magmatism: an initial stage that generated magmas during partial melting of

Planetary geology

CERN Document Server

Gasselt, Stephan

2018-01-01

This book provides an up-to-date interdisciplinary geoscience-focused overview of solid solar system bodies and their evolution, based on the comparative description of processes acting on them. Planetary research today is a strongly multidisciplinary endeavor with efforts coming from engineering and natural sciences. Key focal areas of study are the solid surfaces found in our Solar System. Some have a direct interaction with the interplanetary medium and others have dynamic atmospheres. In any of those cases, the geological records of those surfaces (and sub-surfaces) are key to understanding the Solar System as a whole: its evolution and the planetary perspective of our own planet. This book has a modular structure and is divided into 4 sections comprising 15 chapters in total. Each section builds upon the previous one but is also self-standing. The sections are:  Methods and tools Processes and Sources  Integration and Geological Syntheses Frontiers The latter covers the far-reaching broad topics of exo...

Geometry and kinematics of Majiatan Fold-and-thrust Belt, Western Ordos Basin: implication for Tectonic Evolution of North-South Tectonic Belt

Science.gov (United States)

He, D.

2017-12-01

The Helan-Chuandian North-South Tectonic Belt crossed the central Chinese mainland. It is a boundary of geological, geophysical, and geographic system of Chinese continent tectonics from shallow to deep, and a key zone for tectonic and geomorphologic inversion during Mesozoic to Cenozoic. It is superimposed by the southeastward and northeastward propagation of Qinghai-Tibet Plateau in late Cenozoic. It is thus the critical division for West and East China since Mesozoic. The Majiatan fold-and-thrust belt (MFTB), locating at the central part of HCNSTB and the western margin of Ordos Basin, is formed by the tectonic evolution of the Helan-Liupanshan Mountains. Based on the newly-acquired high-resolution seismic profiles, deep boreholes, and surface geology, the paper discusses the geometry, kinematics, and geodynamic evolution of MFTB. With the Upper Carboniferous coal measures and the pre-Sinian ductile zone as the detachments, MFTB is a multi-level detached thrust system. The thrusting was mainly during latest Jurassic to Late Cretaceous, breaking-forward in the foreland, and resulting in a shortening rate of 25-29%. By structural restoration, this area underwent extension in Middle Proterozoic to Paleozoic, which can be divided into three phases of rifting such as Middle to Late Proterozoic, Cambiran to Ordovician, and Caboniferous to early Permian. It underwent compression since Late Triassic, including such periods as Latest Triassic, Late Jurassic to early Cretaceous, Late Cretaceous to early Paleogene, and Pliocene to Quaternary, with the largest shortening around Late Jurassic to early Cretaceous period (i.e. the mid-Yanshanian movement by the local name). However, trans-extension since Eocene around the Ordos Basin got rise to the formation the Yingchuan, Hetao, and Weihe grabens. It is concluded that MFTB is the leading edge of the intra-continental Helan orogenic belt, and formed by multi-phase breaking-forward thrusting during Late Jurassic to Cretaceous

Geology and geophysics of the West Nubian Paleolake and the Northern Darfur Megalake (WNPL-NDML): Implication for groundwater resources in Darfur, northwestern Sudan

Science.gov (United States)

Elsheikh, Ahmed; Abdelsalam, Mohamed G.; Mickus, Kevin

2011-08-01

The recent delineation of a vastly expanded Holocene paleo-lake (the Northern Darfur Megalake which was originally mapped as the West Nubian Paleolake and here will be referred to as WNPL-NDML) in Darfur in northwestern Sudan has renewed hopes for the presence of an appreciable groundwater resource in this hyper-arid region of Eastern Sahara. This paleolake which existed within a closed basin paleo-drainage system might have allowed for the collection of surface water which was subsequently infiltrated to recharge the Paleozoic-Mesozoic Nubian Aquifer. However, the presence of surface exposures of Precambrian crystalline rocks in the vicinity of the paleolake has been taken as indicating the absence of a thick Paleozoic-Mesozoic sedimentary section capable of holding any meaningful quantity of groundwater. This work integrates surface geology and gravity data to show that WNPL-NDML is underlain by NE-trending grabens forming potential local Paleozoic-Mesozoic aquifers that can hold as much as 1120 km 3 of groundwater if the sedimentary rocks are completely saturated. Nevertheless, it is advised here that recharge of the Nubian aquifer under WNPL-NDML is insignificant and that much of the groundwater is fossil water which was accumulated during different geological times much wetter than today's hyper-arid climate in Eastern Sahara. Excessive extraction will lead to quick depletion of this groundwater resource. This will result in lowering of the water table which in turn might lead to the drying out of the oases in the region which provide important habitats for humans, animals and plants in northern Darfur.

Geologic mapping of Kentucky; a history and evaluation of the Kentucky Geological Survey--U.S. Geological Survey Mapping Program, 1960-1978

Science.gov (United States)

Cressman, Earle Rupert; Noger, Martin C.

1981-01-01

. Paleontologists and stratigraphers of the U.S. Geological Survey cooperated closely with the program. Paleontologic studies were concentrated in the Ordovician of central Kentucky, the Pennsylvanian of eastern and western Kentucky, and the Mesozoic and Cenozoic of westernmost Kentucky. In addition to financial support, the Kentucky Geological Survey provided economic data, stratigraphic support, and drillhole records to the field offices. Geologists of the State Survey made subsurface structural interpretations, constructed bedrock topography maps, and mapped several quadrangles. Some of the problems encountered were the inadequacy of much of the existing stratigraphic nomenclature, the uneven quality of some of the mapping, and the effects of relative isolation on the professional development of some of the geologists. The program cost a total of $20,927,500. In terms of 1960 dollars, it cost $16,035,000; this compares with an original estimate of $12,000,000. Although it is difficult to place a monetary value on the geologic mapping, the program has contributed to newly discovered mineral wealth, jobs, and money saved by government and industry. The maps are used widely in the exploration for coal, oil and gas, fluorspar, limestone, and clay. The maps are also used in planning highways and locations of dams, in evaluating foundation and excavation conditions, in preparing environmental impact statements, and in land-use planning.

Mesozoic dinosaurs from Brazil and their biogeographic implications.

Science.gov (United States)

Bittencourt, Jonathas S; Langer, Max C

2011-03-01

The record of dinosaur body-fossils in the Brazilian Mesozoic is restricted to the Triassic of Rio Grande do Sul and Cretaceous of various parts of the country. This includes 21 named species, two of which were regarded as nomina dubia, and 19 consensually assigned to Dinosauria. Additional eight supraspecific taxa have been identified based on fragmentary specimens and numerous dinosaur footprints known in Brazil. In fact, most Brazilian specimens related to dinosaurs are composed of isolated teeth and vertebrae. Despite the increase of fieldwork during the last decade, there are still no dinosaur body-fossils of Jurassic age and the evidence of ornithischians in Brazil is very limited. Dinosaur faunas from this country are generally correlated with those from other parts of Gondwana throughout the Mesozoic. During the Late Triassic, there is a close correspondence to Argentina and other south-Pangaea areas. Mid-Cretaceous faunas of northeastern Brazil resemble those of coeval deposits of North Africa and Argentina. Southern hemisphere spinosaurids are restricted to Africa and Brazil, whereas abelisaurids are still unknown in the Early Cretaceous of the latter. Late Cretaceous dinosaur assemblages of south-central Brazil are endemic only to genus or, more conspicuously, to species level, sharing closely related taxa with Argentina, Madagascar, Indo-Pakistan and, to a lesser degree, continental Africa.

Recent discoveries of Uruguayan Mesozoic vertebrates

International Nuclear Information System (INIS)

Soto, M.; Perea, D.; Rinderknetch, A.; Ubilla, M.; Da Silva, J.

2007-01-01

Recently, new discoveries of Uruguayan Mesozoic vertebrates have been made, as well as the reinterpretation of already known remains. Its taxonomical and biostratigraphical significance justifies this communication. Concerning the Tacuarembo Formation, on one hand a dipnoan prearticular tooth plate has been reinterpreted as belonging to Ceratodus africanus Haug 1905, a species typical of Late Jurassic-Late Cretaceous deposits of Saharan Africa. This is the second dipnoan taxon recorded in the Tacuarembo Formation, uncovering a previously unrecognized dipnoan diversity in the mid-Mesozoic of South America. On the other hand, a few theropod tooth were confidently identified at the familial level for the first time in our country. The remains include two striated premaxillary tooth crowns, the characters of which, close to Ceratosaurus Marsh 1884, allow to refer them to the family Ceratosauridae, this being the oldest South American record of the family. The striated teeth show strong affinities with those of Late Jurassic ceratosaurids from North America, Iberian Peninsula and Tanzania, which is in accordance with recent proposals about the age of the Lower Member of the Tacuarembo Formation. Concerning the Guichon Formation, we comunicate here in the most important discovery of dinosaur remains in Uruguay. It consist in spatially associated remains from several individuals, including fifty caudal vertebra and several epiphysis, metatarsals and astragali. These materials belong to a titanosaurid sauropod, the characters of which are similar to those of certain Campanian-Maastrichtian titanosaurids. Close to the bones, several eggshell fragments referable to Sphaerovum Mones 1980 - a typical Campanian-Maastrichtian oogenus- were found. This finding represents the first record of sauropod dinosaurs from the Guichon Formation, and suggests a younger age for this unit than early proposed

Fore arc tectonothermal evolution of the El Oro metamorphic province (Ecuador) during the Mesozoic

Science.gov (United States)

Riel, Nicolas; Martelat, Jean-Emmanuel; Guillot, Stéphane; Jaillard, Etienne; Monié, Patrick; Yuquilema, Jonatan; Duclaux, Guillaume; Mercier, Jonathan

2014-10-01

The El Oro metamorphic province of SW Ecuador is a composite massif made of juxtaposed terranes of both continental and oceanic affinity that has been located in a fore-arc position since Late Paleozoic times. Various geochemical, geochronological, and metamorphic studies have been undertaken on the El Oro metamorphic province, providing an understanding of the origin and age of the distinct units. However, the internal structures and geodynamic evolution of this area remain poorly understood. Our structural analysis and thermal modeling in the El Oro metamorphic province show that this fore-arc zone underwent four main geological events. (1) During Triassic times (230-225 Ma), the emplacement of the Piedras gabbroic unit at crustal-root level ( 9 kbar) triggered partial melting of the metasedimentary sequence under an E-W extensional regime at pressure-temperature conditions ranging from 4.5 to 8.5 kbar and from 650 to 900°C for the migmatitic unit. (2) At 226 Ma, the tectonic underplating of the Arenillas-Panupalí oceanic unit (9 kbar and 300°C) thermally sealed the fore-arc region. (3) Around the Jurassic-Cretaceous boundary, the shift from trench-normal to trench-parallel subduction triggered the exhumation and underplating of the high-pressure, oceanic Raspas Ophiolitic Complex (18 kbar and 600°C) beneath the El Oro Group (130-120 Ma). This was followed by the opening of a NE-SW pull-apart basin, which tilted the massif along an E-W subhorizontal axis (110 Ma). (4) In Late Cretaceous times, an N-S compressional event generated heterogeneous deformation due to the presence of the Cretaceous Celica volcanic arc, which acted as a buttress and predominantly affected the central and eastern part of the massif.

New insight on the paleoproterozoic evolution of the São Francisco Craton: Reinterpretation of the geology, the suture zones and the thicknesses of the crustal blocks using geophysical and geological data

Science.gov (United States)

Sampaio, Edson E. S.; Barbosa, Johildo S. F.; Correa-Gomes, Luiz C.

2017-07-01

The Archean-Paleoproterozoic Jequié (JB) and Itabuna-Salvador-Curaçá (ISCB) blocks and their tectonic transition zone in the Valença region, Bahia, Brazil are potentially important for ore deposits, but the geological knowledge of the area is still meager. The paucity of geological information restricts the knowledge of the position and of the field characteristics of the tectonic suture zone between these two crustal segments JB and ISCB. Therefore, interpretation of geophysical data is necessary to supplement the regional structural and petrological knowledge of the area as well as to assist mining exploration programs. The analysis of the airborne radiometric and magnetic data of the region has established, respectively, five radiometric domains and five magnetic zones. Modeling of a gravity profile has defined the major density contrasts of the deep structures. The integrated interpretation of the geophysical data fitted to the known geological information substantially improved the suture zone (lower plate JB versus upper plate ISCB) delimitation, the geological map of the area and allowed to estimate the thicknesses of these two blocks, and raised key questions about the São Francisco Craton tectonic evolution.

Mesozoic fossils (>145 Mya) suggest the antiquity of the subgenera of Daphnia and their coevolution with chaoborid predators.

Science.gov (United States)

Kotov, Alexey A; Taylor, Derek J

2011-05-19

The timescale of the origins of Daphnia O. F. Mueller (Crustacea: Cladocera) remains controversial. The origin of the two main subgenera has been associated with the breakup of the supercontinent Pangaea. This vicariance hypothesis is supported by reciprocal monophyly, present day associations with the former Gondwanaland and Laurasia regions, and mitochondrial DNA divergence estimates. However, previous multilocus nuclear DNA sequence divergence estimates at Pangaea. We examined new and existing cladoceran fossils from a Mesozoic Mongolian site, in hopes of gaining insights into the timescale of the evolution of Daphnia. We describe new fossils of ephippia from the Khotont site in Mongolia associated with the Jurassic-Cretaceous boundary (about 145 MYA) that are morphologically similar to several modern genera of the family Daphniidae, including the two major subgenera of Daphnia, i.e., Daphnia s. str. and Ctenodaphnia. The daphniid fossils co-occurred with fossils of the predaceous phantom midge (Chaoboridae). Our findings indicate that the main subgenera of Daphnia are likely much older than previously known from fossils (at least 100 MY older) or from nuclear DNA estimates of divergence. The results showing co-occurrence of the main subgenera far from the presumed Laurasia/Gondwanaland dispersal barrier shortly after formation suggests that vicariance from the breakup of Pangaea is an unlikely explanation for the origin of the main subgenera. The fossil impressions also reveal that the coevolution of a dipteran predator (Chaoboridae) with the subgenus Daphnia is much older than previously known -- since the Mesozoic.

Coquina of the Lagoa Feia formation, Campos Basin: development geology evolution; Coquinas da formacao Lagoa Feia, Bacia de Campos: evolucao da geologia de desenvolvimento

Energy Technology Data Exchange (ETDEWEB)

Baumgarten, Cleyton S; Dultra, Artur J.C.; Silva Scuta, Maximiano da; Figueiredo, Marcus V.L. de; Sequeira, Maria F.P.B. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

1988-01-01

The evolution of Lagoa Feia coquinas is analysed in its several stages, beginning with the exploratory phase. Special emphasis is devoted to the elements which contribute to improvement in geologic mapping. Development of the reservoir geology, interpretation of the factors that had influence in the reservoir pressure, communications between the fields, causing the low pressure, are discussed. The low transmissibility resultant from the heterogeneity created by the calcite and silica cementation are also reported. 11 figs., 7 refs

Mapping the sub-trappean Mesozoic sediments in the western part of Narmada-Tapti region of Deccan Volcanic Province, India

Science.gov (United States)

Murty, A. S. N.; Sarkar, Dipankar; Sen, Mrinal K.; Sridher, V.; Prasad, A. S. S. S. R. S.

2014-10-01

Deccan Traps spread over large parts of south, west and central India, possibly hiding underneath sediments with hydrocarbon potential. Here, we present the results of seismic refraction and wide-angle reflection experiments along three profiles, and analyze them together the results from all other refraction profiles executed earlier in the western part of Narmada-Tapti region of the Deccan Volcanic Province (DVP). We employ travel time modelling to derive the granitic basement configuration, including the overlying Trap and sub-trappean sediment thickness, if any. Travel time skips and amplitude decay in the first arrival refraction data are indicative of the presence of low velocity sediments (Mesozoic), which are the low velocity zones (LVZ) underneath the Traps. Reflection data from the top of LVZ and basement along with the basement refraction data have been used to derive the Mesozoic sediment thickness. In the middle and eastern parts of the study region between Narmada and Tapti, the Mesozoic sediment thickness varies between 0.5 and 2.0 km and reaches more than 2.5 km south of Sendhwa between Narmada and Tapti Rivers. Thick Mesozoic sediments in the eastern parts are also accompanied by thick Traps. The Mesozoic sediments along the present three profiles may not be much prospective in terms of its thickness, except inside the Cambay basin, where the subtrappean sediment thickness is about 1000-1500 m. In the eastern part of the study area, the deepest section (>4 km) has thick (∼2 km) Mesozoic sediments, but with almost equally thick Deccan Trap cover. Results of the present study provide important inputs for future planning for hydrocarbon exploration in this region.

Nova Scotia offshore to Grand Banks connection : Mesozoic basins on a transform margin

Energy Technology Data Exchange (ETDEWEB)

Conway, L.E.; Martin, M.R.; Enachescu, M.E.; Atkinson, I.; Stead, J.E. [Memorial Univ. of Newfoundland, St. John' s, NL (Canada). Dept. of Earth Sciences and Pan-Atlantic Petroleum Systems Consortium

2005-07-01

The renewed interest in the southern Grand Banks has resulted in new active exploration licenses, seismic acquisition programs and planned drilling in the South Whale and Laurentian basins. The basins are located northeast of the Scotian margin, about 200 km south of the east coast of Newfoundland, in shallow to intermediate waters in an area free of icebergs. The Scotian and Newfoundland offshore areas are separated by the St. Lawrence Tertiary channel. A provincial boundary divides the jurisdiction over sea resources. The long political moratorium which had been imposed on the Laurentian Basin was resolved during the summer of 2003 with the establishment of the provincial boundary. Some regional geological maps of the East Coast Mesozoic sedimentary area indicate continuity between the Orpheus Graben and northern Scotian Shelf and Slope basins (Nova Scotia) and Laurentian and South Whale basins (Newfoundland). In contrast, other maps represents them as being separated by faults or ridges that affect the basin development and complicate the tectono-structural framework initiated in Late Triassic-Early Jurassic periods. Argo salt features found in seismic sections on both sides of the provincial boundary indicate that Atlantic Canada basins were interconnected during the marine phase of the Thethys rifting stage, most likely up to the time of Scotian Shelf break-up. During the Late Jurassic, marine, oil prone source rocks were deposited in the Grand Banks basins and terrestrial to marine, gas prone source rocks were deposited offshore Nova Scotia. Modern industry 2D data donated by GSI and WesternGeco were used to examine the structural and stratigraphic framework of the basins. Common geological and geomorphologic features were emphasized along with the disparity between the structural element, stratigraphy and quality of petroleum systems of the two basins.

Advances in planetary geology, volume 2

International Nuclear Information System (INIS)

1986-07-01

This publication is a continuation of volume 1; it is a compilation of reports focusing on research into the origin and evolution of the solar system with emphasis on planetary geology. Specific reports include a multispectral and geomorphic investigation of the surface of Europa and a geologic interpretation of remote sensing data for the Martian volcano Ascreaus Mons

Terrestrial origin of viviparity in mesozoic marine reptiles indicated by early triassic embryonic fossils.

Science.gov (United States)

Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Rieppel, Olivier; Chen, Guan-bao

2014-01-01

Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction.

Geologic map of the greater Denver area, Front Range urban corridor, Colorado

Science.gov (United States)

Trimble, Donald E.; Machette, Michael N.

1979-01-01

This digital map shows the areal extent of surficial deposits and rock stratigraphic units (formations) as compiled by Trimble and Machette from 1973 to 1977 and published in 1979 under the Front Range Urban Corridor Geology Program. Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes. A convenient feature of the compiled map is its uniform classification of geologic units that mostly matches those of companion maps to the north (USGS I-855-G) and to the south (USGS I-857-F). Published as a color paper map, the Trimble and Machette map was intended for land-use planning in the Front Range Urban Corridor. This map recently (1997-1999) was digitized under the USGS Front Range Infrastructure Resources Project. In general, the mountainous areas in the western part of the map exhibit various igneous and metamorphic bedrock units of Precambrian age, major faults, and fault brecciation zones at the east margin (5-20 km wide) of the Front Range. The eastern and central parts of the map (Colorado Piedmont) depict a mantle of unconsolidated deposits of Quaternary age and interspersed outcroppings of Cretaceous or Tertiary-Cretaceous sedimentary bedrock. The Quaternary mantle comprises eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and a few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone, shale, and limestone bedrock formations form hogbacks and intervening valleys.

Resetting the evolution of marine reptiles at the Triassic-Jurassic boundary.

Science.gov (United States)

Thorne, Philippa M; Ruta, Marcello; Benton, Michael J

2011-05-17

Ichthyosaurs were important marine predators in the Early Jurassic, and an abundant and diverse component of Mesozoic marine ecosystems. Despite their ecological importance, however, the Early Jurassic species represent a reduced remnant of their former significance in the Triassic. Ichthyosaurs passed through an evolutionary bottleneck at, or close to, the Triassic-Jurassic boundary, which reduced their diversity to as few as three or four lineages. Diversity bounced back to some extent in the aftermath of the end-Triassic mass extinction, but disparity remained at less than one-tenth of pre-extinction levels, and never recovered. The group remained at low diversity and disparity for its final 100 Myr. The end-Triassic mass extinction had a previously unsuspected profound effect in resetting the evolution of apex marine predators of the Mesozoic.

Advances in planetary geology

International Nuclear Information System (INIS)

1987-06-01

The surface of Mars displays a broad range of channel and valley features. There is as great a range in morphology as in scale. Some of the features of Martian geography are examined. Geomorphic mapping, crater counts on selected surfaces, and a detailed study of drainage basins are used to trace the geologic evolution of the Margaritifer Sinus Quandrangle. The layered deposits in the Valles Marineris are described in detail and the geologic processes that could have led to their formation are analyzed

GIS-technologies as a mechanism to study geological structures

Science.gov (United States)

Sharapatov, Abish

2014-05-01

Specialized GIS-technologies allow creating multi-parameter models, completing multi-criteria optimisation tasks, and issues of geological profile forecasts using miscellaneous data. Pictorial and attributive geological and geophysical information collected to create GIS database is supplemented by the ERS (Earth's Remote Sensing) data, air spectrometry, space images, and topographic data. Among the important tasks are as follows: a unification of initial geological, geophysical and other types of information on a tectonic position, rock classification and stratigraphic scale; topographic bases (various projectures, scales); the levels of detail and exhaustibility; colors and symbols of legends; data structures and their correlation; units of measurement of physical quantities, and attribute systems of descriptions. Methods of the geological environment investigation using GIS-technology are based on a principle of the research target analogy with a standard. A similarity ratio is quantitative estimate. A geological forecast model is formed by structuring of geological information based on detailed analysis and aggregation of geological and formal knowledge bases on standard targets. Development of a bank of models of the analyzed geological structures of various range, ore-bearing features described by numerous prospecting indicators is the way to aggregate geological knowledge. The south terrain of the Valerianovskaya structure-facies zone (SFZ) of the Torgai paleo-rift structure covered with thick Mesozoic and Cenozoic rocks up to 2,000m is considered a so-called training ground for the development of GIS-technology. Parameters of known magnetite deposits located in the north of the SFZ (Sarybaiskoye, Sokolovskoye, etc.) are used to create the standard model. A meaning of the job implemented involves the following: - A goal-seeking nature of the research being performed and integration of the geological, geo-physical and other data (in many cases, efforts of the

Evolution of viviparous reproduction in Paleozoic and Mesozoic reptiles.

Science.gov (United States)

Blackburn, Daniel G; Sidor, Christian A

2014-01-01

Although viviparity (live-bearing reproduction) is widely distributed among lizards and snakes, it is entirely absent from other extant Reptilia and many extinct forms. However, paleontological evidence reveals that viviparity was present in at least nine nominal groups of pre-Cenozoic reptiles, representing a minimum of six separate evolutionary origins of this reproductive mode. Two viviparous clades (sauropterygians and ichthyopterygians) lasted more than 155 million years, a figure that rivals the duration of mammalian viviparity. Circumstantial evidence indicates that extinct viviparous reptiles had internal fertilization, amniotic fetal membranes, and placentas that sustained developing embryos via provision of respiratory gases, water, calcium, and possibly organic nutrients. Production of offspring via viviparity facilitated the invasion of marine habitats in at least five reptilian lineages. Thus, this pattern of embryonic development and reproduction was central to the ecology and evolution of these ancient animals, much as it is to numerous extant species of vertebrates.

Palaeozoic and Mesozoic igneous activity in the Netherlands: a tectonomagmatic review

NARCIS (Netherlands)

Sissingh, W.

To date, igneous rocks, either intrusive or extrusive, have been encountered in the Palaeozoic-Mesozoic sedimentary series of the Netherlands in some 65 exploration and production wells. Following 17 new isotopic K/Ar age determinations of the recovered rock material (amounting to a total of 28

Crosscutting Development- EVA Tools and Geology Sample Acquisition

Science.gov (United States)

2011-01-01

Exploration to all destinations has at one time or another involved the acquisition and return of samples and context data. Gathered at the summit of the highest mountain, the floor of the deepest sea, or the ice of a polar surface, samples and their value (both scientific and symbolic) have been a mainstay of Earthly exploration. In manned spaceflight exploration, the gathering of samples and their contextual information has continued. With the extension of collecting activities to spaceflight destinations comes the need for geology tools and equipment uniquely designed for use by suited crew members in radically different environments from conventional field geology. Beginning with the first Apollo Lunar Surface Extravehicular Activity (EVA), EVA Geology Tools were successfully used to enable the exploration and scientific sample gathering objectives of the lunar crew members. These early designs were a step in the evolution of Field Geology equipment, and the evolution continues today. Contemporary efforts seek to build upon and extend the knowledge gained in not only the Apollo program but a wealth of terrestrial field geology methods and hardware that have continued to evolve since the last lunar surface EVA. This paper is presented with intentional focus on documenting the continuing evolution and growing body of knowledge for both engineering and science team members seeking to further the development of EVA Geology. Recent engineering development and field testing efforts of EVA Geology equipment for surface EVA applications are presented, including the 2010 Desert Research and Technology Studies (Desert RATs) field trial. An executive summary of findings will also be presented, detailing efforts recommended for exotic sample acquisition and pre-return curation development regardless of planetary or microgravity destination.

From mantle roots to surface eruptions: Cenozoic and Mesozoic continental basaltic magmatism

Czech Academy of Sciences Publication Activity Database

Kämpf, H.; Németh, K.; Puziewicz, J.; Mrlina, Jan; Geissler, W.H.

2015-01-01

Roč. 104, č. 8 (2015), s. 1909-1912 ISSN 1437-3254 Institutional support: RVO:67985530 Keywords : continental basaltic volcanism * BASALT 2013 conference * Cenozoic * Mesozoic Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.133, year: 2015

Structure and dating errors in the geologic time scale and periodicity in mass extinctions

Science.gov (United States)

Stothers, Richard B.

1989-01-01

Structure in the geologic time scale reflects a partly paleontological origin. As a result, ages of Cenozoic and Mesozoic stage boundaries exhibit a weak 28-Myr periodicity that is similar to the strong 26-Myr periodicity detected in mass extinctions of marine life by Raup and Sepkoski. Radiometric dating errors in the geologic time scale, to which the mass extinctions are stratigraphically tied, do not necessarily lessen the likelihood of a significant periodicity in mass extinctions, but do spread the acceptable values of the period over the range 25-27 Myr for the Harland et al. time scale or 25-30 Myr for the DNAG time scale. If the Odin time scale is adopted, acceptable periods fall between 24 and 33 Myr, but are not robust against dating errors. Some indirect evidence from independently-dated flood-basalt volcanic horizons tends to favor the Odin time scale.

The need for New In Situ Measurements to Understand the Climate, Geology and Evolution of Venus.

Science.gov (United States)

Grinspoon, D. H.

2017-12-01

Many measurements needed to address outstanding questions about current processes and evolution of Venus can only be made from in situ platforms such as entry probes, balloons or landers. Among these are precise determination of the value and altitude dependence of the deuterium-to-hydrogen ratio, an important tracer of water history which, while clearly greatly elevated compared to the terrestrial ratio, is still unknown within a large range of uncertainty and appears, based on Venus Express results, to display an enigmatic altitude dependence. Rare gas abundances and isotopes provide clues to volatile sources and histories of outgassing and exospheric escape. Modern mass spectrometry at Venus would yield abundances of the eight stable xenon isotopes, bulk abundances of krypton, and isotopes of neon. Altitude profiles of sulfur-containing chemical species would illuminate global geochemical cycles, including cloud formation, outgassing rates and surface-atmosphere interactions. The altitude profile of wind speeds and radiation fluxes, interpreted in light of the Venus Express and Akatsuki data, would enrich understanding of the global circulation and climate dynamics of Venus. Descent and surface images of carefully chosen locations would lend ground truth to interpretations of the near-global Magellan data sets and provide context for global remote sensing data obtained by future orbiter missions. Landed instruments would provide refinement and calibration for chemical abundance measurements by historical missions as well as direct mineralogical measurements of Venusian surface and subsurface rocks. In concert with atmospheric measurements these would greatly constrain geologic history as well as the nature of surface-atmosphere interactions. Such a suite of measurements will deepen our understanding of the origin and evolution of Venus in the context of Solar System and extrasolar terrestrial planets, determine the level and style of current geological activity

Tectonic evolution of the Anadyr Basin, northeastern Eurasia, and its petroleum resource potential

Science.gov (United States)

Antipov, M. P.; Bondarenko, G. E.; Bordovskaya, T. O.; Shipilov, E. V.

2009-09-01

The published data on the sedimentation conditions, structure, and tectonic evolution of the Anadyr Basin in the Mesozoic and Cenozoic are reviewed. These data are re-examined in the context of modern tectonic concepts concerning the evolution of the northwestern Circum-Pacific Belt. The re-examination allows us not only to specify the regional geology and tectonic history, but also to forecast of the petroleum resource potential of the sedimentary cover based on a new concept. The sedimentary cover formation in the Anadyr Basin is inseparably linked with the regional tectonic evolution. The considered portion of the Chukchi Peninsula developed in the Late Mesozoic at the junction of the ocean-type South Anyui Basin, the Asian continental margin, and convergent zones of various ages extending along the Asia-Pacific interface. Strike-slip faulting and pulses of extension dominated in the Cenozoic largely in connection with oroclinal bending of structural elements pertaining to northeastern Eurasia and northwestern North America against the background of accretion of terranes along the zone of convergence with the Pacific oceanic plates. Three main stages are recognized in the formation of the sedimentary cover in the Anadyr Basin. (1) The lower portion of the cover was formed in the Late Cretaceous-Early Eocene under conditions of alternating settings of passive and active continental margins. The Cenomanian-lower Eocene transitional sedimentary complex is located largely in the southern Anadyr Basin (Main River and Lagoonal troughs). (2) In the middle Eocene and Oligocene, sedimentation proceeded against the background of extension and rifting in the northern part of the paleobasin and compression in its southern part. The compression was caused by northward migration of the foredeep in front of the accretionary Koryak Orogen. The maximum thickness of the Eocene-Oligocene sedimentary complex is noted mainly in the southern part of the basin and in the Central and

Geologic map of the Vail West quadrangle, Eagle County, Colorado

Science.gov (United States)

Scott, Robert B.; Lidke, David J.; Grunwald, Daniel J.

2002-01-01

This new 1:24,000-scale geologic map of the Vail West 7.5' quadrangle, as part of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of the stratigraphy, structure, and geologic hazards in the area on the southwest flank of the Gore Range. Bedrock strata include Miocene tuffaceous sedimentary rocks, Mesozoic and upper Paleozoic sedimentary rocks, and undivided Early(?) Proterozoic metasedimentary and igneous rocks. Tuffaceous rocks are found in fault-tilted blocks. Only small outliers of the Dakota Sandstone, Morrison Formation, Entrada Sandstone, and Chinle Formation exist above the redbeds of the Permian-Pennsylvanian Maroon Formation and Pennsylvanian Minturn Formation, which were derived during erosion of the Ancestral Front Range east of the Gore fault zone. In the southwestern area of the map, the proximal Minturn facies change to distal Eagle Valley Formation and the Eagle Valley Evaporite basin facies. The Jacque Mountain Limestone Member, previously defined as the top of the Minturn Formation, cannot be traced to the facies change to the southwest. Abundant surficial deposits include Pinedale and Bull Lake Tills, periglacial deposits, earth-flow deposits, common diamicton deposits, common Quaternary landslide deposits, and an extensive, possibly late Pliocene landslide deposit. Landscaping has so extensively modified the land surface in the town of Vail that a modified land-surface unit was created to represent the surface unit. Laramide movement renewed activity along the Gore fault zone, producing a series of northwest-trending open anticlines and synclines in Paleozoic and Mesozoic strata, parallel to the trend of the fault zone. Tertiary down-to-the-northeast normal faults are evident and are parallel to similar faults in both the Gore Range and the Blue River valley to the northeast; presumably these are related to extensional deformation that occurred during formation of the northern end of the

Functional morphometric analysis of the furcula in mesozoic birds.

Directory of Open Access Journals (Sweden)

Roger A Close

Full Text Available The furcula displays enormous morphological and structural diversity. Acting as an important origin for flight muscles involved in the downstroke, the form of this element has been shown to vary with flight mode. This study seeks to clarify the strength of this form-function relationship through the use of eigenshape morphometric analysis coupled with recently developed phylogenetic comparative methods (PCMs, including phylogenetic Flexible Discriminant Analysis (pFDA. Additionally, the morphospace derived from the furculae of extant birds is used to shed light on possible flight adaptations of Mesozoic fossil taxa. While broad conclusions of earlier work are supported (U-shaped furculae are associated with soaring, strong anteroposterior curvature with wing-propelled diving, correlations between form and function do not appear to be so clear-cut, likely due to the significantly larger dataset and wider spectrum of flight modes sampled here. Interclavicular angle is an even more powerful discriminator of flight mode than curvature, and is positively correlated with body size. With the exception of the close relatives of modern birds, the ornithuromorphs, Mesozoic taxa tend to occupy unique regions of morphospace, and thus may have either evolved unfamiliar flight styles or have arrived at similar styles through divergent musculoskeletal configurations.

Vietnamese sedimentary basins: geological evolution and petroleum potential

Energy Technology Data Exchange (ETDEWEB)

Fyhn, M.B.W.; Petersen, Henrik I.; Mathiesen, A.; Nielsen, Lars H.; Pedersen, Stig A.S.; Lindstroem, S.; Bojesen-Koefoed, J.A.; Abatzis, I.; Boldreel, L.O.

2010-07-15

The Geological Survey of Denmark and Greenland has worked in Vietnam since 1995 to assess the geology and petroleum potential of the Vietnamese basins. Since 2002 the work has been carried out in cooperation with the Department of Geography and Geology, University of Copenhagen, as part of the ENRECA project (Enhancement of Research Capacity in Developing Countries). The ENRECA project has already completed two phases and a third and final phase has recently started. The initial phase focused on the Phu Khanh and the Song Hong Basins located in the South China Sea offshore north and central Vietnam and the smaller onshore Song Ba Trough. During the second ENRECA phase, completed in 2009, attention shifted towards the Malay - Tho Chu and Phu Quoc basins located in the Gulf of Thailand, SSW of Vietnam. The Phu Quoc Basin continues onshore to the north to form part of the mountainous area between Vietnam and Cambodia. In the recently started third phase of the project, the focus remains on the Phu Quoc Basin in addition to a revisit to the Song Hong Basin on the north Vietnamese margin and onshore beneath the Song Hong (Red River) delta. (LN)

Terrestrial origin of viviparity in mesozoic marine reptiles indicated by early triassic embryonic fossils.

Directory of Open Access Journals (Sweden)

Ryosuke Motani

Full Text Available Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia, which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic. This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction.

Geology of the Yucca Mountain Region, Chapter in Stuckless, J.S., ED., Yucca Mountain, Nevada - A Proposed Geologic Repository for High-Level Radioactive Waste

International Nuclear Information System (INIS)

J.S. Stuckless; D. O'Leary

2006-01-01

Yucca Mountain has been proposed as the site for the Nation's first geologic repository for high-level radioactive waste. This chapter provides the geologic framework for the Yucca Mountain region. The regional geologic units range in age from late Precambrian through Holocene, and these are described briefly. Yucca Mountain is composed dominantly of pyroclastic units that range in age from 11.4 to 15.2 Ma. The proposed repository would be constructed within the Topopah Spring Tuff, which is the lower of two major zoned and welded ash-flow tuffs within the Paintbrush Group. The two welded tuffs are separated by the partly to nonwelded Pah Canyon Tuff and Yucca Mountain Tuff, which together figure prominently in the hydrology of the unsaturated zone. The Quaternary deposits are primarily alluvial sediments with minor basaltic cinder cones and flows. Both have been studied extensively because of their importance in predicting the long-term performance of the proposed repository. Basaltic volcanism began about 10 Ma and continued as recently as about 80 ka with the eruption of cones and flows at Lathrop Wells, approximately 10 km south-southwest of Yucca Mountain. Geologic structure in the Yucca Mountain region is complex. During the latest Paleozoic and Mesozoic, strong compressional forces caused tight folding and thrust faulting. The present regional setting is one of extension, and normal faulting has been active from the Miocene through to the present. There are three major local tectonic domains: (1) Basin and Range, (2) Walker Lane, and (3) Inyo-Mono. Each domain has an effect on the stability of Yucca Mountain

Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration

Energy Technology Data Exchange (ETDEWEB)

Jung, Hun Bok; Kabilan, Senthil; Carson, James P.; Kuprat, Andrew P.; Um, Wooyong; Martin, Paul F.; Dahl, Michael E.; Kafentzis, Tyler A.; Varga, Tamas; Stephens, Sean A.; Arey, Bruce W.; Carroll, KC; Bonneville, Alain; Fernandez, Carlos A.

2014-08-07

Composite Portland cement-basalt caprock cores with fractures, as well as neat Portland cement columns, were prepared to understand the geochemical and geomechanical effects on the integrity of wellbores with defects during geologic carbon sequestration. The samples were reacted with CO2-saturated groundwater at 50 ºC and 10 MPa for 3 months under static conditions, while one cement-basalt core was subjected to mechanical stress at 2.7 MPa before the CO2 reaction. Micro-XRD and SEM-EDS data collected along the cement-basalt interface after 3-month reaction with CO2-saturated groundwater indicate that carbonation of cement matrix was extensive with the precipitation of calcite, aragonite, and vaterite, whereas the alteration of basalt caprock was minor. X-ray microtomography (XMT) provided three-dimensional (3-D) visualization of the opening and interconnection of cement fractures due to mechanical stress. Computational fluid dynamics (CFD) modeling further revealed that this stress led to the increase in fluid flow and hence permeability. After the CO2-reaction, XMT images displayed that calcium carbonate precipitation occurred extensively within the fractures in the cement matrix, but only partially along the fracture located at the cement-basalt interface. The 3-D visualization and CFD modeling also showed that the precipitation of calcium carbonate within the cement fractures after the CO2-reaction resulted in the disconnection of cement fractures and permeability decrease. The permeability calculated based on CFD modeling was in agreement with the experimentally determined permeability. This study demonstrates that XMT imaging coupled with CFD modeling represent a powerful tool to visualize and quantify fracture evolution and permeability change in geologic materials and to predict their behavior during geologic carbon sequestration or hydraulic fracturing for shale gas production and enhanced geothermal systems.

Fission track dating of mesozoic sandstones and its tectonic significance in the Eastern Sichuan Basin, China

International Nuclear Information System (INIS)

Shen Chuanbo; Mei Lianfu; Xu Sihuang

2009-01-01

To establish the tectonic evolution of the eastern Sichuan basin, apatite fission track dating and time-temperature thermal history modeling were carried to analyze on 11 samples collected from Jurassic sandstones. The results indicate that the cooling and exhumation process of the eastern Sichuan basin can be divided into three stages since Cretaceous, (1) a rapid cooling phase between ∼100 and ∼70 Ma, (2) following by a period of relative thermal stability phase between ∼70 and ∼15 Ma, (3) and then a new rapid cooling stage after ∼15 Ma. Two rapid cooling events imply that the eastern Sichuan basin once underwent two tectonic movements since Cretaceous. The first rapid cooling is associated with Mesozoic tectonic reactivation beginning at 100 Ma, which result in folds and faults of the eastern Sichuan basin. The second tectonic movement occurred at 15 Ma, which is related to denudation by compression resulting from the eastward growth of Tibetan plateau uplift.

Charles Darwin in Australia; or How To Introduce Some Local Colour to the Teaching of Evolution, Geology, Meteorology, and the Determination of Longitude.

Science.gov (United States)

Nicholas, Frank W.

The background to Charles Darwin's little-known visit to Australia, and the account of his experiences while here, provide some invaluable historical material for teaching evolution, geology, meteorology, and the determination of longitude. Indeed, by using his Australian experiences as a foundation, it is possible to explain the theory of…

Geochronology and geochemistry of deep-seated crustal xenoliths in the northern North China Craton: Implications for the evolution and structure of the lower crust

Science.gov (United States)

Su, Yuping; Zheng, Jianping; Griffin, William L.; Huang, Yan; Wei, Ying; Ping, Xianquan

2017-11-01

The age and composition of the lower crust are critical in understanding the processes of continental formation and evolution, and deep-seated granulite xenoliths can offer direct information on the lower crust. Here, we report mineral chemistry, whole-rock major and trace elements, Sr-Nd isotopes and zircon U-Pb-Hf results for a suite of deep-seated crustal xenoliths, recently discovered in the Cenozoic basalts of the Nangaoya area in the northern part of the North China Craton (NCC). Based on the P-T estimates, these xenoliths including mafic, intermediate and felsic granulites and hornblendites were sampled from different levels of the lower crust. While a hornblendite has a flat REE pattern, all other xenoliths display LREE enrichment and depletion of Nb, Ta, Th and Ti. The mafic granulite xenolith has relatively high whole-rock εNd(t) value of - 13.37, and yields Mesozoic (188-59 Ma) zircons ages with high εHf(t) values from - 15.3 to - 9.2. The garnet-bearing intermediate granulite-facies rocks show low εNd(t) values from - 16.92 to - 17.48, and reveal both Paleoproterozoic (1948 Ma) and Mesozoic (222-63 Ma) zircon U-Pb ages. Their Mesozoic zircons have lower εHf(t) values (from - 18.4 to - 13.8) than those from the mafic xenolith. The remaining intermediate to felsic xenoliths show Paleoproterozoic zircon ages, and the lowest εNd(t) values (from - 20.78 to - 24.03). The mafic-intermediate granulites with Mesozoic zircons originated from the interaction of lower crust-derived magmas with mantle melts, with higher proportions of mantle magmas involved in the generation of mafic granulite, whereas intermediate to felsic xenoliths without Mesozoic zircons represent ancient Paleoproterozoic to Neoarchean deep crust. These deep-seated xenoliths reveal complicated crustal evolution processes, including crustal growth during Neoarchean (2.5-2.7 Ga), middle Paleoproterozoic (2.2-2.1 Ga) and Mesozoic, and reworking during early Paleoproterozoic, late

Comparison of clay mineral stratigraphy to other proxy palaeoclimate indicators in the Mesozoic of NW Europe.

Science.gov (United States)

Ruffell, Alastair; McKinley, Jennifer M; Worden, Richard H

2002-04-15

This paper reviews the opportunities and pitfalls associated with using clay mineralogical analysis in palaeoclimatic reconstructions. Following this, conjunctive methods of improving the reliability of clay mineralogical analysis are reviewed. The Mesozoic succession of NW Europe is employed as a case study. This demonstrates the relationship between clay mineralogy and palaeoclimate. Proxy analyses may be integrated with clay mineralogical analysis to provide an assessment of aridity-humidity contrasts in the hinterland climate. As an example, the abundance of kaolinite through the Mesozoic shows that, while interpretations may be difficult, the Mesozoic climate of NW Europe was subject to great changes in rates of continental precipitation. We may compare sedimentological (facies, mineralogy, geochemistry) indicators of palaeoprecipitation with palaeotemperature estimates. The integration of clay mineralogical analyses with other sedimentological proxy indicators of palaeoclimate allows differentiation of palaeoclimatic effects from those of sea-level and tectonic change. We may also observe how widespread palaeoclimate changes were; whether they were diachronous or synchronous; how climate, sea level and tectonics interact to control sedimentary facies and what palaeoclimate indicators are reliable.

Proceedings of the 7. Symposium on geology from southeastern Brazil

International Nuclear Information System (INIS)

2001-01-01

This document presents papers on the following subjects: regional geology of the proterozoic and fanerozoic, metallic and non metallic resources, tectoni-sedimentary evolution of the eastern margin Brazil basins and petroleum geology applied to the Santos, Campos and Espirito Santo basins, engineering and environmental geologies, ornamental rocks/building materials/mineral waters/industrial ores

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Field guide to the Mesozoic accretionary complex along Turnagain Arm and Kachemak Bay, south-central Alaska

Science.gov (United States)

Bradley, Dwight C.; Kusky, Timothy M.; Karl, Susan M.; Haeussler, Peter J.

1997-01-01

Turnagain Arm, just east of Anchorage, provides a readily accessible, world-class cross section through a Mesozoic accretionary wedge. Nearly continuous exposures along the Seward Highway, the Alaska Railroad, and the shoreline of Turnagain Arm display the two main constituent units of the Chugach terrane: the McHugh Complex and Valdez Group. In this paper we describe seven bedrock geology stops along Turnagain Arm, and two others in the Chugach Mountains just to the north (Stops 1-7 and 9), which will be visited as part of the May, 1997 field trip of the Alaska Geological Society. Outcrops along Turnagain Arm have already been described in two excellent guidebook articles (Clark, 1981; Winkler and others 1984), both of which remain as useful and valid today as when first published. Since the early 1980's, studies along Turnagain Arm have addressed radiolarian ages of chert and conodont ages of limestone in the McHugh Complex (Nelson and others, 1986, 1987); geochemistry of basalt in the McHugh Complex (Nelson and Blome, 1991); post-accretion brittle faulting (Bradley and Kusky, 1990; Kusky and others, 1997); and the age and tectonic setting of gold mineralization (Haeussler and others, 1995). Highlights of these newer findings will described both in the text below, and in the stop descriptions.Superb exposures along the southeastern shore of Kachemak Bay show several other features of the McHugh Complex that are either absent or less convincing along Turnagain Arm. While none of these outcrops can be reached via the main road network, they are still reasonably accessible - all are within an hour by motorboat from Homer, seas permitting. Here, we describe seven outcrops along the shore of Kachemak Bay that we studied between 1989 and 1993 during geologic mapping of the Seldovia 1:250,000- scale quadrangle. These outcrops (Stops 61-67) will not be part of the 1997 itinerary, but are included here tor the benefit of those who may wish to visit them later.

Geological evolution of the Afro-Arabian dome

Science.gov (United States)

Almond, D. C.

1986-12-01

The Afro-Arabian dome includes the elevated continental regions enclosing the Red Sea, Gulf of Aden, and the Ethiopian rift system, and extends northwards as far as Jordan. It is more than an order of magnitude larger than other African uplifts. Both the structures and the igneous rocks of the dome appear to be products of the superimposition of two, perhaps three, semi-independent generating systems, initiated at different times but all still active. A strain pattern dominated by NW-trending basins and rifts first became established early in the Cretaceous. By the end of the Oligocene, much of the extensional strain had been taken up along the Red Sea and Gulf of Aden axes, which subsequently developed into an ocean. Palaeogene "trap" volcanism of mildly alkaline to transitional character was related to this horizontal extension rather than to doming. Further west, the East Sahara swell has a history of intermittent alkaline volcanicity which began in the Mesozoic and was independent of magmatism in the Afro-Arabian dome. Volcanicity specifically related to doming began in the Miocene along a N-S zone of uplift extending from Ethiopia to Syria. This elongated swell forms the northern termination of the East African system of domes and rifts, characterized by episodic vertical uplift but very little extension. Superimposition of epeirogenic uplift upon structures formed by horizontal extension took place in the Neogene. Volcanicity related to vertical tectonics is mildly alkaline in character, whereas transitional and tholeiitic magmas are found along the spreading axes.

Thermal Maturity Data Used by the U.S. Geological Survey for the U.S. Gulf Coast Region Oil and Gas Assessment

Science.gov (United States)

Dennen, Kristin O.; Warwick, Peter D.; McDade, Elizabeth Chinn

2010-01-01

The U.S. Geological Survey is currently assessing the oil and natural gas resources of the U.S. Gulf of Mexico region using a total petroleum system approach. An essential part of this geologically based method is evaluating the effectiveness of potential source rocks in the petroleum system. The purpose of this report is to make available to the public RockEval and vitrinite reflectance data from more than 1,900 samples of Mesozoic and Tertiary rock core and coal samples in the Gulf of Mexico area in a format that facilitates inclusion into a geographic information system. These data provide parameters by which the thermal maturity, type, and richness of potential sources of oil and gas in this region can be evaluated.

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

International Nuclear Information System (INIS)

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

1981-01-01

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

Mesozoic to Cenozoic tectonic transition process in Zhanhua Sag, Bohai Bay Basin, East China

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Cheng, Yanjun; Wu, Zhiping; Lu, Shunan; Li, Xu; Lin, Chengyan; Huang, Zheng; Su, Wen; Jiang, Chao; Wang, Shouye

2018-04-01

The Zhanhua sag is part of the Bohai Bay intracontinental basin system that has developed since the Mesozoic in East China. The timing of this basin system coincides with the final assembly of East Asia and the development of Western Pacific-type plate margin. Here we use 3-D seismic and core log data to investigate the evolution of this basin and discuss its broad tectonic settings. Our new structural study of Zhanhua sag suggests that there are four major tectonic transitions occurred in the Bohai Bay Basin during Mesozoic and Cenozoic: (1) The first tectonic transition was from stable Craton to thrusting during the Triassic, mainly caused by the South China Block's subduction northward beneath the North China Block, which induced the formation of the NW-striking thrust faults. (2) The second tectonic transition was mainly characterized by a change from compression to extension, which can be further divided into two-stages. At the first stage, two episodes of NW-SE shortening occurred in East Asia during Early-Middle Jurassic and Late Jurassic-earliest Cretaceous, respectively. At the second stage, the extension and left-lateral shearing took place during Early Cretaceous while compression occurred during Late Cretaceous. The NW-striking thrust faults changed to normal faults and the NNE-striking left-lateral strike-slip faults started to influence the eastern part of the basin. (3) The third transition occurred when the NW-SE extension and NNE-striking right-lateral shearing started to form during Paleogene, and the peak deformation happen around 40 Ma due to the change of the subduction direction of Pacific Plate relative to Eurasia Plate. The NE-striking normal faults are the main structure, and the pre-existing NNE-striking strike-slip faults changed from left-lateral to right-lateral. (4) The fourth transition saw the regional subsidence during Neogene, which was probably caused by the India-Asia "Hard collision" between 25 and 20 Ma.

Chirp subbottom profiler data collected in Pamlico Sound on cruise EPamSh-2016 of RV Riggs for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Edgetech 216 chirp data (SEG-Y format) collected for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project, OCE-1130843. Survey area covers...

Characterization of shale gas enrichment in the Wufeng Formation–Longmaxi Formation in the Sichuan Basin of China and evaluation of its geological construction–transformation evolution sequence

Directory of Open Access Journals (Sweden)

Zhiliang He

2017-02-01

Full Text Available Shale gas in Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation in the Sichuan Basin is one of the key strata being explored and developed in China, where shale gas reservoirs have been found in Fuling, Weiyuan, Changning and Zhaotong. Characteristics of shale gas enrichment in the formation shown by detailed profiling and analysis are summarized as “high, handsome and rich”. “High” mainly refers to the high quality of original materials for the formation of shale with excellent key parameters, including the good type and high abundance of organic matters, high content of brittle minerals and moderate thermal evolution. “Handsome” means late and weak deformation, favorable deformation mode and structure, and appropriate uplift and current burial depth. “Rich” includes high gas content, high formation pressure coefficient, good reservoir property, favorable reservoir scale transformation and high initial and final output, with relative ease of development and obvious economic benefit. For shale gas enrichment and high yield, it is important that the combination of shale was deposited and formed in excellent conditions (geological construction, and then underwent appropriate tectonic deformation, uplift, and erosion (geological transformation. Evaluation based on geological construction (evolution sequence from formation to the reservoir includes sequence stratigraphy and sediment, hydrocarbon generation and formation of reservoir pores. Based on geological transformation (evolution sequence from the reservoir to preservation, the strata should be evaluated for structural deformation, the formation of reservoir fracture and preservation of shale gas. The evaluation of the “construction - transformation” sequence is to cover the whole process of shale gas formation and preservation. This way, both positive and negative effects of the formation-transformation sequence on shale gas are assessed. The evaluation

Evolution of Rosaceae Fruit Types Based on Nuclear Phylogeny in the Context of Geological Times and Genome Duplication.

Science.gov (United States)

Xiang, Yezi; Huang, Chien-Hsun; Hu, Yi; Wen, Jun; Li, Shisheng; Yi, Tingshuang; Chen, Hongyi; Xiang, Jun; Ma, Hong

2017-02-01

Fruits are the defining feature of angiosperms, likely have contributed to angiosperm successes by protecting and dispersing seeds, and provide foods to humans and other animals, with many morphological types and important ecological and agricultural implications. Rosaceae is a family with ∼3000 species and an extraordinary spectrum of distinct fruits, including fleshy peach, apple, and strawberry prized by their consumers, as well as dry achenetum and follicetum with features facilitating seed dispersal, excellent for studying fruit evolution. To address Rosaceae fruit evolution and other questions, we generated 125 new transcriptomic and genomic datasets and identified hundreds of nuclear genes to reconstruct a well-resolved Rosaceae phylogeny with highly supported monophyly of all subfamilies and tribes. Molecular clock analysis revealed an estimated age of ∼101.6 Ma for crown Rosaceae and divergence times of tribes and genera, providing a geological and climate context for fruit evolution. Phylogenomic analysis yielded strong evidence for numerous whole genome duplications (WGDs), supporting the hypothesis that the apple tribe had a WGD and revealing another one shared by fleshy fruit-bearing members of this tribe, with moderate support for WGDs in the peach tribe and other groups. Ancestral character reconstruction for fruit types supports independent origins of fleshy fruits from dry-fruit ancestors, including the evolution of drupes (e.g., peach) and pomes (e.g., apple) from follicetum, and drupetum (raspberry and blackberry) from achenetum. We propose that WGDs and environmental factors, including animals, contributed to the evolution of the many fruits in Rosaceae, which provide a foundation for understanding fruit evolution. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

UPPER JURASSIC OUTCROPS ALONG THE CALDAS DA RAINHA DIAPIR, WEST CENTRAL PORTUGAL: A REGIONAL GEOHERITAGE OVERVIEW

OpenAIRE

DINIS, JORGE; BERNARDES, CRISTINA

2004-01-01

The Mesozoic Portuguese geological heritage is very rich and varied, a legacy of the position in the western margin of Iberia and its relationship with the evolution of the North Atlantic, with an interesting tectonic history since the Late Triassic. Regarding the Upper Jurassic several connections can be established between the tectonics and the stratigraphic record in the area surrounding the Caldas da Rainha structure: the basement and salt pillow control on deposition; the beginning of a ...

Caractéristiques de l’évolution de la partie orientale du bloc de Chine du Sud au Mésozoïque supérieur et implications géodynamiques : Etude pluridisciplinaire de la mise en place des massifs granitiques de Qingyang-Jiuhua, Hengshan et de la côte du Fujian et des structures tectoniques associées

OpenAIRE

Wei , Wei

2013-01-01

The vast distribution and long duration of the Late Mesozoic magmatism in the eastern part of South China presents a unique case in the world. This offers a natural laboratory to study the process of magma genesis, the magma emplacement mode, the relationship between magmatism and tectonics, the geodynamic role on the magma emplacement and lithospheric evolution. Since 50’s, particularly 90’s of the last century, geoscientists have made important efforts in geological cartography and carried ...

New aragonite 87Sr/86Sr records of Mesozoic ammonoids and approach to the problem of N, O, C and Sr isotope cycles in the evolution of the Earth

Science.gov (United States)

Zakharov, Yuri D.; Dril, Sergei I.; Shigeta, Yasunari; Popov, Alexander M.; Baraboshkin, Eugenij Y.; Michailova, Irina A.; Safronov, Peter P.

2018-02-01

New Sr isotope data from well-preserved aragonite ammonoid shell material from the Mesozoic are compared with that from a living Nautilus shell. The prominent negative Sr isotope excursions known from the Middle Permian, Jurassic and Cretaceous probably have their origins in intensive plate tectonic activity, followed by enhanced hydrothermal activity at the mid-ocean ridges (mantle volcanism) which supplied low radiogenic Sr to seawater. The maximum positive (radiogenic) shift in the lower Mesozoic Sr isotope curve (Lower Triassic peak) was likely caused by a significant expansion of dry land surfaces (Dabie-Sulu Triassic orogeny) and their intensive silicate weathering in conditions of extreme warming and aridity in the very end of the Smithian, followed by warm and humid conditions in the late Spathian, which apparently resulted in a significant oceanic input of radiogenic Sr through riverine flux. The comparatively high 87Sr/86Sr ratio obtained from the living Nautilus shell is probably a function of both the Alpine orogeny, which was accompanied by significant continental weathering and input of radiogenic Sr to the oceans, and the weakening of mantle volcanism.

Geophysical identification and geological Implications of the Southern Alaska Magnetic Trough

Science.gov (United States)

Saltus, R.W.; Hudson, T.L.; Wilson, Frederic H.

2003-01-01

The southern Alaska magnetic trough (SAMT) is one of the fundamental, crustal-scale, magnetic features of Alaska. It is readily recognized on 10 km upward-continued aeromagnetic maps of the state. The arcuate SAMT ranges from 30 to 100 km wide and extends in two separate segments along the southern Alaska margin for about 1200 km onshore (from near the Alaska/Canada border at about 60 degrees north latitude to the Bering Sea) and may continue an additional 500 km or more offshore (in the southern Bering Sea). The SAMT is bordered to the south by the southern Alaska magnetic high (SAMH) produced by strongly magnetic crust and to the north by a magnetically quiet zone that reflects weakly magnetic interior Alaska crust. Geophysically, the SAMT is more than just the north-side dipole low associated with the SAMH. Several modes of analysis, including examination of magnetic potential (pseudogravity) and profile modeling, indicate that the source of this magnetic trough is a discrete, crustal-scale body. Geologically, the western portion of the SAMT coincides to a large degree with collapsed Mesozoic Kahiltna flysch basin. This poster presents our geophysical evidence for the extent and geometry of this magnetic feature as well as initial geological synthesis and combined geologic/geophysical modeling to examine the implications of this feature for the broad scale tectonic framework of southern Alaska.

Chirp subbottom profiler data collected in Pamlico Sound on cruise RVRiggs_07_31_2013 of RV Riggs for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Edgetech 216 chirp data (SEG-Y format) collected for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project, OCE-1130843. Survey area covers...

Chirp subbottom profiler data collected in Pamlico Sound on cruise RVRiggs_07_30_2013 of RV Riggs for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Edgetech 216 chirp data (SEG-Y format) collected for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project, OCE-1130843. Survey area covers...

Geology of the Yucca Mountain Region, Chapter in Stuckless, J.S., ED., Yucca Mountain, Nevada - A Proposed Geologic Repository for High-Level Radioactive Waste

Energy Technology Data Exchange (ETDEWEB)

J.S. Stuckless; D. O' Leary

2006-09-25

Yucca Mountain has been proposed as the site for the Nation's first geologic repository for high-level radioactive waste. This chapter provides the geologic framework for the Yucca Mountain region. The regional geologic units range in age from late Precambrian through Holocene, and these are described briefly. Yucca Mountain is composed dominantly of pyroclastic units that range in age from 11.4 to 15.2 Ma. The proposed repository would be constructed within the Topopah Spring Tuff, which is the lower of two major zoned and welded ash-flow tuffs within the Paintbrush Group. The two welded tuffs are separated by the partly to nonwelded Pah Canyon Tuff and Yucca Mountain Tuff, which together figure prominently in the hydrology of the unsaturated zone. The Quaternary deposits are primarily alluvial sediments with minor basaltic cinder cones and flows. Both have been studied extensively because of their importance in predicting the long-term performance of the proposed repository. Basaltic volcanism began about 10 Ma and continued as recently as about 80 ka with the eruption of cones and flows at Lathrop Wells, approximately 10 km south-southwest of Yucca Mountain. Geologic structure in the Yucca Mountain region is complex. During the latest Paleozoic and Mesozoic, strong compressional forces caused tight folding and thrust faulting. The present regional setting is one of extension, and normal faulting has been active from the Miocene through to the present. There are three major local tectonic domains: (1) Basin and Range, (2) Walker Lane, and (3) Inyo-Mono. Each domain has an effect on the stability of Yucca Mountain.

Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates.

Science.gov (United States)

Motani, Ryosuke; Jiang, Da-Yong; Tintori, Andrea; Ji, Cheng; Huang, Jian-Dong

2017-05-17

The fossil record of a major clade often starts after a mass extinction even though evolutionary rates, molecular or morphological, suggest its pre-extinction emergence (e.g. squamates, placentals and teleosts). The discrepancy is larger for older clades, and the presence of a time-scale-dependent methodological bias has been suggested, yet it has been difficult to avoid the bias using Bayesian phylogenetic methods. This paradox raises the question of whether ecological vacancies, such as those after mass extinctions, prompt the radiations. We addressed this problem by using a unique temporal characteristic of the morphological data and a high-resolution stratigraphic record, for the oldest clade of Mesozoic marine reptiles, Ichthyosauromorpha. The evolutionary rate was fastest during the first few million years of ichthyosauromorph evolution and became progressively slower over time, eventually becoming six times slower. Using the later slower rates, estimates of divergence time become excessively older. The fast, initial rate suggests the emergence of ichthyosauromorphs after the end-Permian mass extinction, matching an independent result from high-resolution stratigraphic confidence intervals. These reptiles probably invaded the sea as a new ecosystem was formed after the end-Permian mass extinction. Lack of information on early evolution biased Bayesian clock rates. © 2017 The Author(s).

Geological investigations for geological model of deep underground geoenvironment at the Mizunami Underground Research Laboratory (MIU)

International Nuclear Information System (INIS)

Tsuruta, Tadahiko; Tagami, Masahiko; Amano, Kenji; Matsuoka, Toshiyuki; Kurihara, Arata; Yamada, Yasuhiro; Koike, Katsuaki

2013-01-01

Japan Atomic Energy Agency (JAEA) is performing a geoscientific research project, the Mizunami Underground Research Laboratory (MIU) project, in order to establish scientific and technological basis for geological disposal of high-level radioactive wastes. The MIU is located in crystalline rock environment, in Mizunami City, central Japan. Field investigations include geological mapping, reflection seismic surveys, several borehole investigations and geological investigations in the research galleries to identify the distribution and heterogeneity of fractures and faults that are potential major flowpaths for groundwater. The results of these field investigations are synthesized and compiled for the purpose of geological modeling. The field investigations indicate that the Main Shaft at the MIU intersected low permeability NNW oriented faults. A high permeability fracture zone in the granite, a significant water inflow point, was observed in the Ventilation Shaft. Development of the geological model focusing 3D spatial relationships at different scales and evolution of the geoenvironment are underway. This paper describes geological investigations applied in the MIU project, focusing on the evaluation of their effectiveness to understand for deep underground geoenvironment. (author)

Geodynamic evolution of the Taiwan-Luzon-Mindoro belt since the late eocene

Science.gov (United States)

Stephan, Jean François; Blanchet, René; Rangin, Claude; Pelletier, Bernard; Letouzey, Jean; Muller, Carla

1986-05-01

The structural framework of the Taiwan-Luzon-Mindoro belt (or festoon) is described, following three major transects: the Luzon transect with active subduction and active island arc; the Taiwan transect with active collision; the Mindoro transect with active subduction and inactive collision. Based on this geological study and on available geophysical data, a model for the geodynamic evolution of this portion of the Philippine Sea and Eurasia Plates boundary is proposed in a succession of reconstructions between the Late Eocene and the Present. The major geodynamic events are: (1) beginning of the opening of the South China Sea (S.C.S.) in Lower Oligocene times, contemporaneous with obduction of the Zambales and Angat ophiolites on Luzon. (2) subduction of a Mesozoic (?) oceanic basin along the proto-Manila trench from the Upper Oligocene to the Lower Miocene. (3) obduction of the South China Sea oceanic crust onto the Chinese and Reed Bank—Calamian passive margins in Middle Miocene time (14-15 Ma) related to a major kinematic reorganization (end of opening of the S.C.S.). (4) beginning of collision between the Luzon microblock and the two margins of the S.C.S. in the Upper Miocene (~ 7 Ma); collision is still active in Taiwan whereas it stopped in Mindoro during the Pliocene.

Dynamics of dental evolution in ornithopod dinosaurs

Science.gov (United States)

Strickson, Edward; Prieto-Márquez, Albert; Benton, Michael J.; Stubbs, Thomas L.

2016-07-01

Ornithopods were key herbivorous dinosaurs in Mesozoic terrestrial ecosystems, with a variety of tooth morphologies. Several clades, especially the ‘duck-billed’ hadrosaurids, became hugely diverse and abundant almost worldwide. Yet their evolutionary dynamics have been disputed, particularly whether they diversified in response to events in plant evolution. Here we focus on their remarkable dietary adaptations, using tooth and jaw characters to examine changes in dental disparity and evolutionary rate. Ornithopods explored different areas of dental morphospace throughout their evolution, showing a long-term expansion. There were four major evolutionary rate increases, the first among basal iguanodontians in the Middle-Late Jurassic, and the three others among the Hadrosauridae, above and below the split of their two major clades, in the middle of the Late Cretaceous. These evolutionary bursts do not correspond to times of plant diversification, including the radiation of the flowering plants, and suggest that dental innovation rather than coevolution with major plant clades was a major driver in ornithopod evolution.

Reconstruction of crustal blocks of California on the basis of initial strontium isotopic compositions of Mesozoic granitic rocks

Science.gov (United States)

Kistler, Ronald Wayne; Peterman, Zell E.

1978-01-01

Initial 87Sr/ 86 Sr was determined for samples of Mesozoic granitic rocks in the vicinity of the Garlock fault zone in California. These data along with similar data from the Sierra Nevada and along the San Andreas fault system permit a reconstruction of basement rocks offset by the Cenozoic lateral faulting along both the San Andreas and Garlock fault systems. The location of the line of initial 87Sr/ 86 Sr = 0.7060 can be related to the edge of the Precambrian continental crust in the western United States. Our model explains the present configuration of the edge of Precambrian continental crust as the result of two stages of rifting that occurred about 1,250 to 800 m.y. ago, during Belt sedimentation, and about 600 to 350 m.y. ago, prior to and during the development of the Cordilleran geosyncline and to left-lateral translation along a locus of disturbance identified in the central Mojave Desert. The variations in Rb, Sr, and initial 87Sr/ 86 Sr of the Mesozoic granitic rocks are interpreted as due to variations in composition and age of the source materials of the granitic rocks. The variations of Rb, Sr, and initial 87Sr/ 86 Sr in Mesozoic granitic rocks, the sedimentation history during the late Precambrian and Paleozoic, and the geographic position of loci of Mesozoic magmatism in the western United States are related to the development of the continental margin and different types of lithosphere during rifting.

International Project - Atlas of Geological Maps of Central Asia and Adjacent Territories 1:2 500 000 Scale - the Status and the Development Prospects

Science.gov (United States)

Leonov, Y.; Petrov, O. V.; Dong, S.; Morozov, A.; Shokalsky, S.; Pospelov, I.; Erinchek, Y.; Milshteyn, E.

2011-12-01

This project is launched by geological surveys of Russia, China, Mongolia, Kazakhstan and the Republic of Korea with participation of National Academies of Sciences under the aegis of the Commission for the Geological Map of the World since 2004. The project goal is the compilation and subsequent monitoring of the set of digital geological maps for the large part of the Asian continent (20 million km2). Each country finances its own part of the project while all the issues concerning methods and technologies are discussed collectively during annual meetings and joint filed excursions. At the 33d IGC, were shown 4 digital maps of the Atlas at 1: 2,5M - geological, tectonic, metallogenic and energy resources. Geological and energy resources maps were compiled and published by the Chinese part while tectonic and metallogenic maps by Russian side (VSEGEI, Saint-Petersburg). The geological map was also used as the base for the compilation of the other maps of the Atlas. On the tectonic map colours indicate several stages of the continental crust consolidation within fold belts, their tectonic reworking and rifting. The map also shows rock complexes-indicators of geodynamic settings. In the platform areas, the colour reflects the time of beginning of the sedimentary cover formation while its shades reflect the thickness of the sediments. The metallogenic map of the Atlas depicts 1380 objects of metallogenic zoning (from super-provinces to ore clusters) and is accompanied with a database (more than 5000 ore deposits). The map of energy resources with the database contains information on the of coal- and oil-and-gas-bearing basins and main coal and hydrocarbon deposits. In 2009 the study area was extended to the North, East and South in order to embrace bigger territory with ore-bearing Mesozoic-Cenozoic volcanic belts of the Asian continent's Pacific margin. According to nearest plans, discussed with the head of Rosnedra Dr. Anatoliy Ledovskikh and the director of the

Chirp subbottom profiler data collected in Pamlico Sound on cruise RVRiggs_05_23_24_2012 of RV Riggs for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Edgetech 216 chirp data (SEG-Y format) collected for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project, OCE-1130843. Survey area covers...

Chirp subbottom profiler data collected in Pamlico Sound on cruise RVRiggs_05_20_22_2014 of RV Riggs for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Edgetech 216 chirp data (SEG-Y format) collected for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project, OCE-1130843. Survey area covers the...

Geological, geochemical, and geophysical studies by the U.S. Geological Survey in Big Bend National Park, Texas

Science.gov (United States)

Page, W.R.; Turner, K.J.; Bohannon, R.G.; Berry, M.E.; Williams, V.S.; Miggins, D.P.; Ren, M.; Anthony, E.Y.; Morgan, L.A.; Shanks, P.W.C.; Gray, J. E.; Theodorakos, P.M.; Krabbenhoft, D. P.; Manning, A.H.; Gemery-Hill, P. A.; Hellgren, E.C.; Stricker, C.A.; Onorato, D.P.; Finn, C.A.; Anderson, E.; Gray, J. E.; Page, W.R.

2008-01-01

Big Bend National Park (BBNP), Tex., covers 801,163 acres (3,242 km2) and was established in 1944 through a transfer of land from the State of Texas to the United States. The park is located along a 118-mile (190-km) stretch of the Rio Grande at the United States-Mexico border. The park is in the Chihuahuan Desert, an ecosystem with high mountain ranges and basin environments containing a wide variety of native plants and animals, including more than 1,200 species of plants, more than 450 species of birds, 56 species of reptiles, and 75 species of mammals. In addition, the geology of BBNP, which varies widely from high mountains to broad open lowland basins, also enhances the beauty of the park. For example, the park contains the Chisos Mountains, which are dominantly composed of thick outcrops of Tertiary extrusive and intrusive igneous rocks that reach an altitude of 7,832 ft (2,387 m) and are considered the southernmost mountain range in the United States. Geologic features in BBNP provide opportunities to study the formation of mineral deposits and their environmental effects; the origin and formation of sedimentary and igneous rocks; Paleozoic, Mesozoic, and Cenozoic fossils; and surface and ground water resources. Mineral deposits in and around BBNP contain commodities such as mercury (Hg), uranium (U), and fluorine (F), but of these, the only significant mining has been for Hg. Because of the biological and geological diversity of BBNP, more than 350,000 tourists visit the park each year. The U.S. Geological Survey (USGS) has been investigating a number of broad and diverse geologic, geochemical, and geophysical topics in BBNP to provide fundamental information needed by the National Park Service (NPS) to address resource management goals in this park. Scientists from the USGS Mineral Resources and National Cooperative Geologic Mapping Programs have been working cooperatively with the NPS and several universities on several research studies within BBNP

Formation and Evolution of Lakshmi Planum (V-7), Venus: Assessment of Models using Observations from Geological Mapping

Science.gov (United States)

Ivanov, M. A.; Head, James W.

2008-01-01

Lakshmi Planum is a high-standing plateau (3.5-4.5 km above MPR) surrounded by the highest mountain ranges on Venus. Lakshmi represents a unique type of elevated region different from dome-shaped and rifted rises and tessera-bearing crustal plateaus. The unique characteristics of Lakshmi suggest that it formed by an unusual combination of processes and played an important role in Venus geologic history. Lakshmi was studied with Venera-15/16 and Magellan data, resulting in two classes of models, divergent and convergent, to explain its unusual topographic and morphologic characteristics. Divergent models explain Lakshmi as a site of mantle upwelling due to rising and subsequent collapse of a mantle diapir; such models explain emplacement of a lava plateau inside Lakshmi and, in some circumstances, formation of the mountain ranges. The convergent models consider Lakshmi as a locus of mantle downwelling, convergence, underthrusting, and possible subduction. Key features in these models are the mountain ranges, high topography of Lakshmi interior, and the large volcanic centers in the plateau center. These divergent and convergent models entail principally different mechanisms of formation and suggest different geodynamic regimes on Venus. Almost all models make either explicit or implicit predictions about the type and sequence of major events during formation and evolution of Lakshmi and thus detailed geological mapping can be used to test them. Here we present the results of such geological mapping (the V-7 quadrangle, 50-75degN, 300-360degE; scale 1:5M) that allows testing the proposed models for Lakshmi.

Correspondence of Mesozoic Eustatic Sea-Level Change with Palaeoclimate Proxies: Evidence for Glacio-Eustasy?

Science.gov (United States)

Simmons, M.; Davies, A.; Gréselle, B.

2011-12-01

Large-scale changes in stratigraphic architecture and facies that are brought about by changes in relative sea-level have been the focus of much academic and industry study over the last few decades. The authors, plus numerous colleagues, have studied over 11,000 stratigraphic sections worldwide. By applying biostratigraphic and chemostratigraphic calibration in suitable locations from this dataset it is possible to demonstrate over 250 synchronous global sequence stratigraphic events in the Phanerozoic including over 100 in the Mesozoic. This then raises the question - what causes globally synchronous eustatic sea-level change? To answer this question requires an understanding of both the pace and amplitude of the observed eustatic sea-level change. In successions where duration can be deduced from orbital forcing cycles, our observed sea-level changes appear to be relatively rapid - less than 500,000 years, for example, for sea-level rises in the Late Jurassic. The amplitude of such rises is in the order of tens of metres. Such rates and amplitudes as inferred from our global model preclude tectonism as a primary driver and implicate glacio-eustacy as a key driving mechanism, even in supposed "greenhouse times". Given the clear economic importance of understanding the underlying mechanisms driving this eustatic change we have compiled records of key isotopic proxies through the entire Mesozoic in an effort to explore the relationship between global sea-level and palaeoclimate. Our research reveals a clear link between many large-scale maximum flooding events with known episodes of palaeoclimatic warming and between climatic cooling events and lowstand intervals, further implicating glacio-eustacy. In addition to the isotopic proxy evidence we have also compiled direct indicators for the occurrence of cold polar conditions, including the presence of ice sheets, in the Mesozoic (e.g. tillites, glendonites). This has been incorporated into plate tectonic

Volcanic rises on Venus: Geology, formation, and sequence of evolution

Science.gov (United States)

Senske, D. A.; Stofan, E. R.; Bindschadler, D. L.; Smrekar, S. E.

1993-01-01

Large centers of volcanism on Venus are concentrated primarily in the equatorial region of the planet and are associated with regional topographic rises. Analysis of both radar images and geophysical data suggest that these uplands are sites of mantle upwelling. Magellan radar imaging provides a globally contiguous data set from which the geology of these regions is evaluated and compared. In addition, high resolution gravity data currently being collected provide a basis to assess the relationship between these uplands and processes in the planet's interior. Studies of the geology of the three largest volcanic highlands (Beta Regio, Atla Regio, Western Eistla Regio) show them to be distinct, having a range of volcanic and tectonic characteristics. In addition to these large areas, a number of smaller uplands are identified and are being analyzed (Bell Regio, Imdr Regio, Dione Regio (Ushas, Innini, and Hathor Montes), and Themis Regio). To understand better the mechanisms by which these volcanic rises form and evolve, we assess their geologic and geophysical characteristics.

Constraints on the topographic evolution of Corsica and Sardinia from geological and geomorphic analyses

Science.gov (United States)

Quye-Sawyer, Jennifer; Whittaker, Alexander; Roberts, Gareth; Rood, Dylan

2017-04-01

The western Mediterranean Sea and its surroundings form part of a well-studied region whose geodynamic history is broadly known. However, how the topography of this area has responded to its tectonic and geodynamic influences is not fully understood. In particular, the relative importance of convergent, extensional and dynamic process is not known. Here we focus on the islands of Corsica, France, and Sardinia, Italy, which have played an important role in Alpine-Apennine system. They experienced a similar kinematic history during the Cenozoic, however their different positions on the Tethyan margin allow the relative effects of Alpine collision and rates of back-arc stretching to be compared. In particular, the two stages of back-arc extension (Liguro-Provençal basin to the west and Tyrrhenian Sea on the east) can provide information about how rollback-induced extension developed with time from the late Oligocene to the present. The two islands are historically tectonically quiescent, however they still preserve evidence of collision and subsequent extension from slab roll-back. In this study we have used a combination of geological and geomorphic techniques to provide new constraints into the vertical motions of Corsica and Sardinia. To quantify the spatial and temporal landscape evolution we have integrated stratigraphic, structural and thermochronological data and re-evaluated these alongside present-day geomorphic and geophysical observations. In addition, we have used digital elevation models to acquire 2030 fluvial longitudinal profiles for both islands. Knickpoints identified on these longitudinal profiles have been compared to geological maps to test the influence of rock strength on erosion. Our analysis reveals the presence of non-lithologically controlled knickpoints which we interpret to have been created by Miocene to Recent changes in uplift rate of the landscape. The longitudinal profiles were subsequently used in drainage inversion modelling, whose

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

Science.gov (United States)

Wang, M.

2017-12-01

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

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2002-09-25

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 2 of the project has been reservoir characterization, 3-D modeling and technology transfer. This effort has included six tasks: (1) the study of rockfluid interactions, (2) petrophysical and engineering characterization, (3) data integration, (4) 3-D geologic modeling, (5) 3-D reservoir simulation and (6) technology transfer. This work was scheduled for completion in Year 2. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions is near completion. Observations regarding the diagenetic processes influencing pore system development and

Chirp subbottom profiler data collected in Pamlico Sound on cruise SndPt_05_21_22_2012 of RV Riggs for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Edgetech 216 chirp data (SEG-Y format) collected for the Coastal Hydrodynamics and Natural Geologic Evolution (CHaNGE) project, OCE-1130843. Survey area covers...

Fundamentals of Structural Geology

Science.gov (United States)

Pollard, David D.; Fletcher, Raymond C.

2005-09-01

Fundamentals of Structural Geology provides a new framework for the investigation of geological structures by integrating field mapping and mechanical analysis. Assuming a basic knowledge of physical geology, introductory calculus and physics, it emphasizes the observational data, modern mapping technology, principles of continuum mechanics, and the mathematical and computational skills, necessary to quantitatively map, describe, model, and explain deformation in Earth's lithosphere. By starting from the fundamental conservation laws of mass and momentum, the constitutive laws of material behavior, and the kinematic relationships for strain and rate of deformation, the authors demonstrate the relevance of solid and fluid mechanics to structural geology. This book offers a modern quantitative approach to structural geology for advanced students and researchers in structural geology and tectonics. It is supported by a website hosting images from the book, additional colour images, student exercises and MATLAB scripts. Solutions to the exercises are available to instructors. The book integrates field mapping using modern technology with the analysis of structures based on a complete mechanics MATLAB is used to visualize physical fields and analytical results and MATLAB scripts can be downloaded from the website to recreate textbook graphics and enable students to explore their choice of parameters and boundary conditions The supplementary website hosts color images of outcrop photographs used in the text, supplementary color images, and images of textbook figures for classroom presentations The textbook website also includes student exercises designed to instill the fundamental relationships, and to encourage the visualization of the evolution of geological structures; solutions are available to instructors

Research of mining and geological conditions for geological exploration in Pre-Caucasian region

Directory of Open Access Journals (Sweden)

Р. А. Гасумов

2017-12-01

Full Text Available Taking into consideration natural depletion of reserves of hydrocarbons in Mesozoic deposits of the majority of operated deposits of North Caucasus and for the purpose of further development of oil and gas producing industry in the region it is necessary to involve a carbonaceous complex of Jura of West Pre-Caucasus with the burial depth of more than 5300 m in the development. When drafting engineering design for a construction of exploratory wells in complex mining and geological conditions driven by anomalously high overburden pressure and temperature, use of thoroughly studied field geological information and taking into consideration the experience of boring similar wells is important. The paper provides analysis of geophysical data, the results of complex studies of reservoir porosity and permeability features of rocks picked out of core-samples of the first exploratory well on Krupskaya zone (porosity, permeability, electrical, acoustic, lithological characteristics, pressure-and-temperature conditions. The information obtained allowed to specify technological parameters of boring and tailing-in and to give recommendations regarding the way of exploratory wells boring and use of borehole equipment. In order to avoid the development of significant hydrodynamic pressure in the borehole which provokes gas showings it is necessary to keep on a certain level of minimal values of mud rheology parameters (dynamic shear stress τ = 70¸135 dPa; plastic viscosity η = 25¸35 mPa·s. For the purpose of real-time keeping of overbalance with anomalously high overburden pressure, control and regulation of calculated head pressure a stripper head should be included into the equipment configuration. Furthermore well head equipment and blowout preventer equipment must be designed for expected gradient of overburden pressure.

Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage.

Science.gov (United States)

Benson, Roger B J; Campione, Nicolás E; Carrano, Matthew T; Mannion, Philip D; Sullivan, Corwin; Upchurch, Paul; Evans, David C

2014-05-01

Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of

Textural and mineralogical study of the San Gregorio de Polanco mesozoic basic dams

International Nuclear Information System (INIS)

Scaglia, S.; Muzio, R.; Masquelin, H.

2010-01-01

This work is about the preliminary results of petrographic study in Mesozoic basic dikes located around San Gregorio de Polanco (Tacuarembo department. Uruguay). The textural mineralogical study conducted by scanning electron microscopy confirms the presence of significant late hydrothermal activity which are represented by the conspicuous presence of interstitial barite mineralization level

Reconstructing Magmatic-Hydrothermal Systems via Geologic Mapping of the Tilted, Cross-sectional Exposures of the Yerington District, Nevada

Science.gov (United States)

Dilles, J. H.; Proffett, J. M.

2011-12-01

The Jurassic Yerington batholith was cut by Miocene to recent normal faults and tilted ~90° west (Proffett, 1977). Exposures range from the volcanic environment to ~6 km depth in the batholith. Magmatic-hydrothermal fluids derived from the Luhr Hill granite and associated porphyry dikes produced characteristic porphyry copper mineralization and rock alteration (K-silicate, sericitic, and advanced argillic) in near-vertical columnar zones above cupolas on the deep granite. In addition, saline brines derived from the early Mesozoic volcanic and sedimentary section intruded by the batholith were heated and circulated through the batholith producing voluminous sodic-calcic and propylitic alteration. The magnetite-copper ore body at Pumpkin Hollow is hosted in early Mesozoic sedimentary rocks in the contact aureole of the batholith, and appears to be an IOCG type deposit produced where the sedimentary brines exited the batholith. Although many advances in understanding of Yerington have been made by lab-based geochronology and geochemistry studies, the first order igneous and hydrothermal features were recognized first in the 1960s and 1970s and are best documented by geological mapping at a variety of scales ranging from 1:500 to 1:24,000. The Anaconda technique of mapping mine benches, trenches, and drill cores was perfected here (Einaudi, 1997), and other techniques were used for surface exposures. The geologic and hydrothermal alteration maps establish that hydrothermal alteration accompanied each of several porphyry dike intrusions, and affected more than 100 km3 of rock. Both zonation in alteration mineralogy and vein orientations allow reconstruction of source areas and >5 km-long flow-paths of hydrothermal fluids through the batholith and contact aureole.

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2003-09-25

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling that utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 3 of the project has been reservoir characterization, 3-D modeling, testing of the geologic-engineering model, and technology transfer. This effort has included six tasks: (1) the study of seismic attributes, (2) petrophysical characterization, (3) data integration, (4) the building of the geologic-engineering model, (5) the testing of the geologic-engineering model and (6) technology transfer. This work was scheduled for completion in Year 3. Progress on the project is as follows: geoscientific reservoir characterization is completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions has been completed. Observations regarding the diagenetic

Petrology and Geochemistry of Unbrecciated Harzburgitic Diogenite MIL 07001: A Window Into Vestan Geological Evolution

Science.gov (United States)

Mittlefehldt, D. W.; Peng, Z. X.; Mertzman, S. A.; Mertzman, K. R.

2014-01-01

There is a strong case that asteroid 4 Vesta is the parent of the howardite, eucrite and diogenite (HED) meteorites. Models developed for the geological evolution of Vesta can satisfy the compositions of basaltic eucrites that dominate in the upper crust. The bulk compositional characteristics of diogenites - cumulate harzburgites and orthopyroxenites from the lower crust - do not fit into global magma ocean models that can describe the compositions of basaltic and cumulate eucrites. Recent more detailed formation models do make provision for a more complicated origin for diogenites, but this model has yet to be completely vetted. Compositional studies of bulk samples has led to the hypothesis that many diogenites were formed late by interaction of their parent melts with a eucritic crust, but those observations may alternatively be explained by subsolidus equilibration of trace elements between orthopyroxene and plagioclase and Ca-phosphate in the rocks. Differences in radiogenic Mg-26 content between diogenites and eucrites favors early formation of the former, not later formation. Understanding the origin of diogenites is crucial for understanding the petrologic evolution of Vesta. We have been doing coordinated studies of a suite of diogenites including petrologic investigations, bulk rock major and trace element studies, and in situ trace element analyses of orthopyroxene. Here we will focus on an especially unusual, and potentially key, diogenite, MIL 07001.

Paleozoic and Mesozoic deformations in the central Sierra Nevada, California

Science.gov (United States)

Nokleberg, Warren J.; Kistler, Ronald Wayne

1980-01-01

Analysis of structural and stratigraphic data indicates that several periods of regional deformation, consisting of combined folding, faulting, cataclasis, and regional metamorphism, occurred throughout the central Sierra Nevada during Paleozoic and Mesozoic time. The oldest regional deformation occurred alono northward trends during the Devonian and Mississippian periods in most roof pendants containing lower Paleozoic metasedimentary rocks at the center and along the crest of the range. This deformation is expressed in some roof pendants by an angular unconformity separating older thrice-deformed from younger twice-deformed Paleozoic metasedimentary rocks. The first Mesozoic deformation, which consisted of uplift and erosion and was accompanied by the onset of Andean-type volcanism during the Permian and Triassic, is expressed by an angular unconformity in several roof pendants from the Saddlebag Lake to the Mount Morrison areas. This unconformity is defined by Permian and Triassic andesitic to rhyolitic metavolcanic rocks unconformably overlying more intensely deformed Pennsylvanian, Permian(?), and older metasedimentary rocks. A later regional deformation occurred during the Triassic along N. 20?_30? W. trends in Permian and Triassic metavolcanic rocks of the Saddlebag Lake and Mount Dana roof pendants, in upper Paleozoic rocks of the Pine Creek roof pendant, and in the Calaveras Formation of the western metamorphic belt; the roof pendants are crosscut by Upper Triassic granitic rocks of the Lee Vining intrusive epoch. A still later period of Early and Middle Jurassic regional deformation occurred along N. 30?-60? E. trends in upper Paleozoic rocks of the Calaveras Formation of the western metamorphic belt. A further period of deformation was the Late Jurassic Nevadan orogeny, which occurred along N. 20?_40? W. trends in Upper Jurassic rocks of the western metamorphic belt that are crosscut by Upper Jurassic granitic rocks of the Yosemite intrusive epoch

Correlated evolution of sternal keel length and ilium length in birds

Directory of Open Access Journals (Sweden)

Tao Zhao

2017-07-01

Full Text Available The interplay between the pectoral module (the pectoral girdle and limbs and the pelvic module (the pelvic girdle and limbs plays a key role in shaping avian evolution, but prior empirical studies on trait covariation between the two modules are limited. Here we empirically test whether (size-corrected sternal keel length and ilium length are correlated during avian evolution using phylogenetic comparative methods. Our analyses on extant birds and Mesozoic birds both recover a significantly positive correlation. The results provide new evidence regarding the integration between the pelvic and pectoral modules. The correlated evolution of sternal keel length and ilium length may serve as a mechanism to cope with the effect on performance caused by a tradeoff in muscle mass between the pectoral and pelvic modules, via changing moment arms of muscles that function in flight and in terrestrial locomotion.

Structural evolution and tectonic style of the Tunisian central Atlas; role of inherited faults in compressive tectonics (Ghoualguia anticline)

Science.gov (United States)

Briki, Haithem; Ahmadi, Riadh; Smida, Rabiaa; Rekhiss, Farhat

2018-04-01

Geological mapping, field cross sections, structural analyses and new subsurface data were used to characterize the geometry and tectonic setting of the Ghoualguia structure, which is an E-W-trending anticline located between the Kalaa Khasba and Rouhia troughs of the central Tunisian Atlas. The results show an important NE-SW extensional phase during the Mesozoic, as demonstrated by synsedimentary normal faults (NW-SE and E-W) and thickness variations. In the Aouled Mdoua area, the absence of Paleocene-Eocene rocks indicates that the eastern and western parts of the Ghoualguia structure were separated by high topography. In addition, the angular unconformity observed between the Upper Cretaceous unit (Abiod Fm.) and the upper Eocene series (Souar Fm.) provide evidence of a tilted-block structure delineated by North-South faults. A major compressional phase during the middle to late Miocene created various detachment levels that originated mainly in the Triassic and Cretaceous deposits. Faults were reactivated as thrust and strike-slip faults, creating fault-related fold structures. In the core of the Ghoualguia fold, an original S-dipping normal fault underwent reverse movement as a back thrust. Fault-slip data indicate that the area records a major NE-SW extensional phase that took place during the late Miocene and Pliocene. A balanced cross section provides insight into the existence of two main detachment levels rooted in the Triassic (depth ± 6 km) and the lower Cretaceous (depth ± 2.5 km). The balanced cross section highlights a shortening of about 2.5 km along cross section and 1.5 km in the central part of the Ghoualguia anticline. This work underlines the predominant role of the inherited Mesozoic structures during the evolution of the Atlassic range and their influence on the geometry of the central Tunisian atlas.

A Passerine Bird's evolution corroborates the geologic history of the island of New Guinea.

Science.gov (United States)

Deiner, Kristy; Lemmon, Alan R; Mack, Andrew L; Fleischer, Robert C; Dumbacher, John P

2011-05-06

New Guinea is a biologically diverse island, with a unique geologic history and topography that has likely played a role in the evolution of species. Few island-wide studies, however, have examined the phylogeographic history of lowland species. The objective of this study was to examine patterns of phylogeographic variation of a common and widespread New Guinean bird species (Colluricincla megarhyncha). Specifically, we test the mechanisms hypothesized to cause geographic and genetic variation (e.g., vicariance, isolation by distance and founder-effect with dispersal). To accomplish this, we surveyed three regions of the mitochondrial genome and a nuclear intron and assessed differences among 23 of the 30 described subspecies from throughout their range. We found support for eight highly divergent lineages within C. megarhyncha. Genetic lineages were found within continuous lowland habitat or on smaller islands, but all individuals within clades were not necessarily structured by predicted biogeographic barriers. There was some evidence of isolation by distance and potential founder-effects. Mitochondrial DNA sequence divergence among lineages was at a level often observed among different species or even genera of birds (5-11%), suggesting lineages within regions have been isolated for long periods of time. When topographical barriers were associated with divergence patterns, the estimated divergence date for the clade coincided with the estimated time of barrier formation. We also found that dispersal distance and range size are positively correlated across lineages. Evidence from this research suggests that different phylogeographic mechanisms concurrently structure lineages of C. megarhyncha and are not mutually exclusive. These lineages are a result of evolutionary forces acting at different temporal and spatial scales concordant with New Guinea's geological history.

A Passerine Bird's evolution corroborates the geologic history of the island of New Guinea.

Directory of Open Access Journals (Sweden)

Kristy Deiner

2011-05-01

Full Text Available New Guinea is a biologically diverse island, with a unique geologic history and topography that has likely played a role in the evolution of species. Few island-wide studies, however, have examined the phylogeographic history of lowland species. The objective of this study was to examine patterns of phylogeographic variation of a common and widespread New Guinean bird species (Colluricincla megarhyncha. Specifically, we test the mechanisms hypothesized to cause geographic and genetic variation (e.g., vicariance, isolation by distance and founder-effect with dispersal. To accomplish this, we surveyed three regions of the mitochondrial genome and a nuclear intron and assessed differences among 23 of the 30 described subspecies from throughout their range. We found support for eight highly divergent lineages within C. megarhyncha. Genetic lineages were found within continuous lowland habitat or on smaller islands, but all individuals within clades were not necessarily structured by predicted biogeographic barriers. There was some evidence of isolation by distance and potential founder-effects. Mitochondrial DNA sequence divergence among lineages was at a level often observed among different species or even genera of birds (5-11%, suggesting lineages within regions have been isolated for long periods of time. When topographical barriers were associated with divergence patterns, the estimated divergence date for the clade coincided with the estimated time of barrier formation. We also found that dispersal distance and range size are positively correlated across lineages. Evidence from this research suggests that different phylogeographic mechanisms concurrently structure lineages of C. megarhyncha and are not mutually exclusive. These lineages are a result of evolutionary forces acting at different temporal and spatial scales concordant with New Guinea's geological history.

Lakes, Lagerstaetten, and Evolution

Science.gov (United States)

Kordesch, E. G.; Park, L. E.

2001-12-01

nonmarine organisms, and thus the evolution of freshwater organisms, can occur in a short geologic timespan. Because of their unique and varied conditions, the evolution of nonmarine organisms may be linked to lake basin type as well as lake longevity.

Evolution of the Atmosphere and Oceans: Evidence from Geological ...

Indian Academy of Sciences (India)

Geological Survey of India since 1974. ... sulphate bacteria, for instance, use H2S instead o[water, and CO2 to produce carbohydrates in the presence of light energy. ... weathering and in the oxidation of reduced gases of volcanic origin.

Geologic evolution of the Paraiba do Sul complex, in the central part of the Ribeira belt, based on the geochemistry and U-Pb geochronology studies

International Nuclear Information System (INIS)

Valladares, Claudia Sayao

1996-01-01

Aiming the definition of the Complexo Paraiba do Sul evolution, the work presents a geochronological approach by the U-Pb method, considered appropriate to study polideformed terrains. The minerals used to the U-Pb dating (zircon, titanite and monazite) provides information about the ages of rock generation and the successive geological events the rocks were submitted. The U-Pb geochronological approach is pioneer in the investigated area and two questions referent to the Complexo Paraiba do Sul evolution in the central part of the Ribeira belt, were the aim of this approach. The first of them refers to the crystallization epoch and the gneisses metamorphism, interpreted here like orthogneisses, called Unidade Quirino of the Complexo Paraiba do Sul. The second refers to the metamorphism ages and meta sedimentary unit deformation. Looking for the contribution to the Complexo Paraiba do Sul evolution understanding, this work presents the data based on the geologic map of this area, comprising part of the Folha Volta Redonda (1:50.000), including petrographic, structural and microtectonic studies. It also presents and discusses the results of: 17 U-Pb analysis in zircon and titanite of the Complexo Paraiba do Sul orthogneisses collection; 24 geochemical analysis of major, minor, trace elements and ETR of the same collection; an U-Pb analysis in titanite of the Unidade Sao Joao, 5 U-Pb analysis in titanites and/or monazites of granites and granitoids; 12 geochemical analysis including major, minor and trace elements and ETR, in granites and sills of leucogranites. Finally, the data achieved were integrated with the objective to elaborate an evolutive view of the Complexo Paraiba do Sul

Were Oceanic Plateaus Instrumental for Calcareous Nannoplankton Evolution?

Science.gov (United States)

Erba, E.; Casellato, C.; Bottini, C.

2011-12-01

The history of calcareous nannoplankton shows a general increase in species richness through the Mesozoic. Fertility and chemistry of the oceans, climate and pCO2 seem instrumental for nannoplankton abundance, diversification and adaptation, but high-resolution chronology of paleobiological and geological events is crucial for the understanding of evolutionary processes relative to ecosystem perturbations. Natural variations in atmospheric CO2 are essentially triggered by igneous activity and the role of ocean crust production in the evolution of seawater composition, nutrient cycling, climate change and, consequently, in calcareous nannoplankton biodiversity, might be more relevant than generally thought. Indeed, two major steps in nannofloral Mesozoic evolution correlate with construction of gigantic oceanic plateaus, namely the Shatsky Rise (SR) (Tithonian/Berriasian boundary interval) and the Ontong Java Plateau (OJP) (Barremian/Aptian boundary interval). During the latest Jurassic calcareous nannoplankton experienced a rapid diversification and rise in abundance of several taxa including heavily calcified nannoliths with consequent major increase in biogenic calcite production. The Tithonian origination of coccoliths and nannoliths suggests ideal paleoecological conditions for calcareous nannoplankton, presumably thriving in stable, relatively oligotrophic and cool oceans under low pCO2. Recent data indicate that this speciation and calcification episode was interrupted during magnetochron CM19r, prior to massive diversification of nannoconids. In the late Barremian-early Aptian interval, the nannoconid decline and crisis are paralleled by a major nannoplankton (mainly coccolith) speciation episode. Such calcification failure and coccolith diversification might reflect disruption of the thermocline, increased fertility and warming under excess CO2 levels. These evolutionary steps show rapid speciation, but differ because nannoliths became dominant in the late

Multiple Mesozoic mineralization events in South China—an introduction to the thematic issue

Science.gov (United States)

Hu, Rui-Zhong; Zhou, Mei-Fu

2012-08-01

Mesozoic mineral deposits in South China include world-class deposits of W, Sn and Sb and those that provide the major sources of Ta, Cu, Hg, As, Tl, Pb, Zn, Au and Ag for the entire country. These deposits can be classified into polymetallic hydrothermal systems closely related to felsic intrusive rocks (Sn-W -Mo granites, Cu porphyries, polymetallic and Fe skarns, and polymetallic vein deposits) and low-temperature hydrothermal systems with no direct connection to igneous activities (MVT deposits, epithermal Au and Sb deposits). Recent studies have shown that they formed in the Triassic (Indosinian), Jurassic-Cretaceous (Early Yanshanian), and Cretaceous (Late Yanshanian) stages. Indosinian deposits include major MVT (Pb-Zn-Ag) deposits and granite-related W-Sn deposits. Early Yanshanian deposits are low-temperature Sb-Au and high-temperature W-Sn and Cu porphyry types. Many Late Yanshanian deposits are low-temperature Au-As-Sb-Hg and U deposits, and also include high-temperature W-Sn polymetallic deposits. The formation of these deposits is linked with a specific tectonothermal evolution and igneous activities. This special issue brings together some of the latest information in eight papers that deal with the origins and tectonic environments of mineral deposits formed in these stages. We anticipate that this issue will stimulate more interests in these ore deposits in South China.

Geologic evolution of the Jemez Mountains and their potential for future volcanic activity

International Nuclear Information System (INIS)

Burton, B.W.

1982-01-01

Geophysical and geochemical data and the geologic history of the Rio Grande rift and the vicinity of the Jemez Mountains are summarized to determine the probability of future volcanic activity in the Los Alamos, New Mexico area. The apparent cyclic nature of volcanism in the Jemez Mountains may be related to intermittent thermal inputs into the volcanic system beneath the region. The Jemez lineament, an alignment of late Cenozoic volcanic centers that crosses the rift near Los Alamos, has played an important role in the volcanic evolution of the Jemez Mountains. Geophysical data suggest that there is no active shallow magma body beneath the Valles caldera, though magma probably exists at about 15 km beneath this portion of the rift. The rate of volcanism in the Jemez Mountains during the last 10 million years has been 5 x 10 -9 /km 2 /y. Lava or ash flows overriding Laboratory radioactive waste disposal sites would have little potential to release radionuclides to the environment. The probability of a new volcano intruding close enough to a radioactive waste disposal site to effect radionuclide release is 2 x 10 -7 /y

Geology of the Nevada Test Site and nearby areas, southern Nevada

International Nuclear Information System (INIS)

Sinnock, S.

1982-10-01

The Department of Energy's Nevada Test Site (NTS) lies in the southern part of the Great Basin Section of the Basin and Range Physiographic Province. This report addresses the geological setting of the NTS in the context of the current waste isolation policy. The intent is to provide a synthesis of geological conditions at the NTS and nearby areas so that a general background of information is available for assessing the possible role of geology in providing protections for humans from buried radioactive wastes. The NTS is characterized by alluvium-filled, topgraphically closed valleys surrounded by ranges composed of Paleozoic sedimentary rocks and Tertiary volcanic tuffs and lavas. The Paleozoic rocks are a miogeosynclinal sequence of about 13,000 ft of pre-Cambrian to Cambrian clastic deposits (predominantly quartzites) overlain by about 14,000 ft of Cambrian through Devonian carbonates, 8000 ft of Mississippian argillites and quartzites, and 3000 ft of Pennsylvanian to Permian limestones. Tertiary volcanic rocks are predominatly silicic composition and were extruded from numerous eruptive centers during Miocene and Pliocene epochs. Within eruptive caldera depressions, volcanic deposits accumulated to perhaps 10,000 ft in total thickness, thinning to extinction outward from the calderas. Extrusion of minor amounts of basalts accompanied Pliocene and Pleistocene filling of structural basins with detritus from the ranges. Regional compressional and extensional structures as well as local volcanic structures occur in the NTS region. Normal extensional faulting coincided with the outbreak of volcanism during the Miocene and was superimposed on existing Mesozoic structures. Continued extensional deformation may be occurring at the present time

The Evolution and Fossil History of Sensory Perception in Amniote Vertebrates

Science.gov (United States)

Müller, Johannes; Bickelmann, Constanze; Sobral, Gabriela

2018-05-01

Sensory perception is of crucial importance for animals to interact with their biotic and abiotic environment. In amniotes, the clade including modern mammals (Synapsida), modern reptiles (Reptilia), and their fossil relatives, the evolution of sensory perception took place in a stepwise manner after amniotes appeared in the Carboniferous. Fossil evidence suggests that Paleozoic taxa had only a limited amount of sensory capacities relative to later forms, with the majority of more sophisticated types of sensing evolving during the Triassic and Jurassic. Alongside the evolution of improved sensory capacities, various types of social communication evolved across different groups. At present there is no definitive evidence for a relationship between sensory evolution and species diversification. It cannot be excluded, however, that selection for improved sensing was partially triggered by biotic interactions, e.g., in the context of niche competition, whereas ecospace expansion, especially during the Mesozoic, might also have played an important role.

Database for the Geologic Map of the Skykomish River 30-Minute by 60-Minute Quadrangle, Washington (I-1963)

Science.gov (United States)

Tabor, R.W.; Frizzell, V.A.; Booth, D.B.; Waitt, R.B.; Whetten, J.T.; Zartman, R.E.

2006-01-01

This digital map database has been prepared from the published geologic map of the Skykomish River 30- by 60-minute quadrangle by the senior author. Together with the accompanying text files as PDF, it provides information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The authors mapped most of the bedrock geology at 1:100,000 scale, but compiled Quaternary units at 1:24,000 scale. The Quaternary contacts and structural data have been much simplified for the 1:100,000-scale map and database. The spatial resolution (scale) of the database is 1:100,000 or smaller. From the eastern-most edges of suburban Seattle, the Skykomish River quadrangle stretches east across the low rolling hills and broad river valleys of the Puget Lowland, across the forested foothills of the North Cascades, and across high meadowlands to the bare rock peaks of the Cascade crest. The Straight Creek Fault, a major Pacific Northwest structure which almost bisects the quadrangle, mostly separates unmetamorphosed and low-grade metamorphic Paleozoic and Mesozoic oceanic rocks on the west from medium- to high-grade metamorphic rocks on the east. Within the quadrangle the lower grade rocks are mostly Mesozoic melange units. To the east, the higher-grade terrane is mostly the Chiwaukum Schist and related gneisses of the Nason terrane and invading mid-Cretaceous stitching plutons. The Early Cretaceous Easton Metamorphic Suite crops out on both sides of the Straight Creek fault and records it's dextral displacement. On the south margin of the quadrangle, the fault separates the lower Eocene Swauk Formation on the east from the upper Eocene and Oligocene(?) Naches Formation and, farther north, its correlative Barlow Pass Volcanics the west. Stratigraphically equivalent rocks of the Puget Group crop out farther to the west. Rocks of

Significant achievements in the planetary geology program. Final report

International Nuclear Information System (INIS)

Head, J.W.

1978-12-01

Developments reported at a meeting of principal investigators for NASA's planetology geology program are summarized. Topics covered include the following: constraints on solar system formation; asteriods, comets, and satellites; constraints on planetary interiors; volatiles and regoliths; instrument development techniques; planetary cartography; geological and geochemical constraints on planetary evolution; fluvial processes and channel formation; volcanic processes; Eolian processes; radar studies of planetary surfaces; cratering as a process, landform, and dating method; and the Tharsis region of Mars. Activities at a planetary geology field conference on Eolian processes are reported and techniques recommended for the presentation and analysis of crater size-frequency data are included

Geologic-tectonic evolutional characteristics and prospecting potential for ISL-amenable sandstone-type uranium deposits; in Sichuan basin

International Nuclear Information System (INIS)

Liu Jianhua; Zhu Xiyang; Wang Sili; Wei Jisheng

2005-01-01

Through the analysis on geologic-tectonic evolution of Sichuan basin, authors of this paper suggest: because of the heterogeneity of the basin basement and cover structures resulting from the lateral dividing, those segments in the basin that experienced only weak tectonic activation, and those that were uplifted and eroded earlier have not been intensely deformed, and have not experienced long-period burying. Rocks in those segments are poorly consolidated and there exist conditions for the formation of large-area artesian slope at the transitional sites between uplifted and subsided areas, possessing favourable hydrogeologic conditions for long-term infiltration of groundwater. These areas must be the targets for prospecting for ISL-amenable sandstone-type uranium deposits. Correspondingly, the Triassic and Jurassic where loose sand bodies are hosted are prospecting target horizons for uranium. (authors)

Timing and implications for the late Mesozoic geodynamic settings of eastern North China Craton: Evidences from K-Ar dating age and sedimentary-structural characteristics records of Lingshan Island, Shandong Province

Science.gov (United States)

Li, Jie; Jin, Aiwen; Hou, Guiting

2017-12-01

The Lingshan Island in Shandong Province in the eastern North China Craton, well known for the Late Mesozoic multi-scale slide-slump structures is related to paleo-earthquake. Terrigenous clastic rocks, volcanic clastic rocks and volcanic lavas are extensively exposed in the Lingshan Island and its adjacent regions of the Shandong Province, which led to fierce debates on their ages, sedimentary characteristics and tectono-sedimentary evolution. In this contribution, we present the characteristics of the Late Mesozoic stratigraphy in the Lingshan Island. Whole-rock K-Ar dating of dyke at Beilaishi and rhyolites at Laohuzui of the Lingshan Island yielded ages of 159 Ma and 106-92 Ma which coincides with the Laiyang Period rifting and the Qingshan Period rifting in the Jiaolai Basin, respectively. On the basis of the analysis to the Late Mesozoic sedimentary environment of `flysch' and `molasse'-like formations as well as tectonic stress fields reconstruction, four episodes of the tectono-sedimentary evolution were established in the Lingshan Island and its adjacent regions in the eastern North China Craton. They consist of two episodes of extensional events for the syn-rift, and two episodes of compression events for the inversion of the post-rift. The entire episodes can be summarized as follows: (1) the first syn-rift NW-SE extension in Laiyang Period can be identified by the `flysch' formation (Unit 1) and by emplacement of the NE-trending dyke in the Laiyang Group. This syn-rift episode can be related to the NW-SE post-orogenic extension resulted from the gravity collapse of the thickened lithosphere along the Sulu Orogen. (2) The first post-rift NW-SE inversion, which was caused by the NW-directed subduction of Izanaqi Plate, can be well documented by the `X' type conjugate joints as well as slide slump folds in Unit 1. (3) The second syn-rift NW-SE extension in Qingshan Period is characterized by rhyolite rocks (Unit 2). This syn-rift episode can be considered

A model for the analysis of a normal evolution scenarios for a deep geological granite repository for high-level radioactive waste

International Nuclear Information System (INIS)

Cormenzana Lopez, J.L.; Cunado, M.A.; Lopez, M.T.

1996-01-01

The methodology usually used to evaluate the behaviour of deep geological repositories for high-level radioactive wastes comprises three phases: Identification of factors (processes, characteristics and events) that can affect the repository. Generation of scenarios. In general, a normal evolution scenario (Reference Scenario) and various disruptive scenarios (earthquake, human intrusion, etc) are considered. Evaluation of the behaviour of the repository in each scenario. The normal evolution scenario taking into account all factors with a high probability of occurrence is the first to be analysed. The performance assessment of behaviour being carried out by ENRESA for the AGP Granite has led to the identification of 63 of these factors. To analyse repository behaviour in the normal evolution scenario, it is necessary to first of all create an integrated model of the global system. This is a qualitative model including the 63 factors identified. For a global view of a such a complex system, it is very useful to graphically display the relationship between factors in an Influence Diagram. This paper shows the Influence Diagram used in the analysis of the AGP Granite Reference Scenario. (Author)

A bibliography of planetary geology principal investigators and their associates, 1981 - 1982

Science.gov (United States)

Plescia, J. B. (Compiler)

1982-01-01

Over 800 publications submitted by researchers supported through NASA's Planetary Geology Program are cited and an author/editor index is provided. Entries are listed under the following subjects: (1) general interest topics; (2) solar system, comets, asteroids, and small bodies; (3) geologic mapping, geomorphology, and stratigraphy; (4) structure, tectonics, geologic and geophysical evolution; (5) impact craters: morphology, density, and geologic studies; (6) volcanism; (7) fluvial, mass wasting, and periglacial processes; (8) Eolian studies; (9) regolith, volatile, atmosphere, and climate; (10) remote sensing, radar, and photometry; and (11) cartography, photogrammetry, geodesy, and altimetry.

Geological evolution of the Antongil Craton, NE Madagascar

Science.gov (United States)

Schofield, D.I.; Thomas, Ronald J.; Goodenough, K.M.; De Waele, B.; Pitfield, P.E.J.; Key, R.M.; Bauer, W.; Walsh, G.J.; Lidke, D.J.; Ralison, A.V.; Rabarimanana, M.; Rafahatelo, J.-M.; Randriamananjara, T.

2010-01-01

The Antongil Craton, along with the Masora and Antananarivo cratons, make up the fundamental Archaean building blocks of the island of Madagascar. They were juxtaposed during the late-Neoproterozoic to early Palaeozoic assembly of Gondwana. In this paper we give a synthesis of the geology of the Antongil Craton and present previously published and new geochemical and U-Pb zircon analyses to provide an event history for its evolution.The oldest rocks in the Antongil Craton form a nucleus of tonalitic gneiss, characteristic of Palaeo-Mesoarchaean cratons globally, including phases dated between 3320 ?? 14. Ma to 3231 ?? 6. Ma and 3187 ?? 2. Ma to 3154 ?? 5. Ma. A series of mafic dykes was intruded into the Mesoarchaean tonalites and a sedimentary succession was deposited on the craton prior to pervasive deformation and migmatisation of the region. The age of deposition of the metasediments has been constrained from a volcanic horizon to around 3178 ?? 2. Ma and subject to migmatisation at around 2597 ?? 49. Ma. A subsequent magmatic episode generated voluminous, weakly foliated granitic rocks, that also included additions from both reworked older crustal material and younger source components. An earlier granodiorite-dominated assemblage, dated between 2570 ?? 18. Ma and 2542 ?? 5. Ma, is largely exposed in xenoliths and more continuously in the northern part of the craton, while a later monzogranite-dominated phase, dated between 2531 ?? 13. Ma and 2513 ?? 0.4. Ma is more widely developed. Together these record the stabilisation of the craton, attested to by the intrusion of a younger dyke swarm, the age of which is constrained by a sample of metagabbro dated at 2147 ?? 6. Ma, providing the first evidence for Palaeoproterozoic rocks from the Antongil Craton.The youngest events recorded in the isotopic record of the Antongil Craton are reflected in metamorphism, neocrystallisation and Pb-loss at 792 ?? 130. Ma to 763 ?? 13. Ma and 553 ?? 68. Ma. These events are

Generalized surficial geologic map of the Fort Irwin area, San Bernadino: Chapter B in Geology and geophysics applied to groundwater hydrology at Fort Irwin, California

Science.gov (United States)

Miller, David M.; Menges, Christopher M.; Lidke, David J.; Buesch, David C.

2014-01-01

The geology and landscape of the Fort Irwin area, typical of many parts of the Mojave Desert, consist of rugged mountains separated by broad alluviated valleys that form the main coarse-resolution features of the geologic map. Crystalline and sedimentary rocks, Mesozoic and older in age, form most of the mountains with lesser accumulations of Miocene sedimentary and volcanic rocks. In detail, the area exhibits a fairly complex distribution of surficial deposits resulting from diverse rock sources and geomorphology that has been driven by topographic changes caused by recent and active faulting. Depositional environments span those typical of the Mojave Desert: alluvial fans on broad piedmonts, major intermittent streams along valley floors, eolian sand dunes and sheets, and playas in closed valleys that lack through-going washes. Erosional environments include rocky mountains, smooth gently sloping pediments, and badlands in readily eroded sediment. All parts of the landscape, from regional distribution of mountains, valleys, and faults to details of degree of soil development in surface materials, are portrayed by the surficial geologic map. Many of these attributes govern infiltration and recharge, and the surface distribution of permeable rock units such as Miocene sedimentary and volcanic rocks provides a basis for evaluating potential groundwater storage. Quaternary faults are widespread in the Fort Irwin area and include sinistral, east-striking faults that characterize the central swath of the area and the contrasting dextral, northwest-striking faults that border the east and west margins. Bedrock distribution and thickness of valley-fill deposits are controlled by modern and past faulting, and faults on the map help to identify targets for groundwater exploration.

A three-dimensional model of the Pyrenees and their foreland basins from geological and gravimetric data

Science.gov (United States)

Wehr, H.; Chevrot, S.; Courrioux, G.; Guillen, A.

2018-06-01

We construct a three-dimensional geological model of the Pyrenees and their foreland basins with the Geomodeller. This model, which accounts for different sources of geological and geophysical informations, covers the whole Pyrenees, from the Atlantic Ocean to the Mediterranean Sea, and from the Iberian range to the Massif Central, down to 70 km depth. We model the geological structure with a stratigraphic column composed of a superposition of layers representing the mantle, lower, middle, and upper crusts. The sedimentary basins are described by two layers which allow us to make the distinction between Mesozoic and Cenozoic sediments, which are characterized by markedly different densities and seismic velocities. Since the Pyrenees result from the convergence between the Iberian and European plates, we ascribe to each plate its own stratigraphic column in order to be able to model the imbrication of Iberian and European crusts along this fossile plate boundary. We also introduce two additional units which describe the orogenic prism and the water column in the Bay of Biscay and in the Mediterranean Sea. The last ingredient is a unit that represents bodies of shallow exhumed and partly serpentinized lithospheric mantle, which are assumed to produce the positive Bouguer gravity anomalies in the North Pyrenean Zone. A first 3D model is built using only the geological information coming from geological maps, drill-holes, and seismic sections. We use the potential field method implemented in Geomodeller to interpolate these geological data. This model is then refined in order to better explain the observed Bouguer anomalies by adding new constraints on the main crustal interfaces. The final model explains the observed Bouguer anomalies with a standard deviation less than 3.4 mGal, and reveals anomalous deep structures beneath the eastern Pyrenees.

The evolution of the callovo-oxfordian argillite site, Eastern France

International Nuclear Information System (INIS)

Brulhet, J.

2004-01-01

In France, investigations on the feasibility of a repository for long-lived radioactive waste in a deep geological formation are carried out according to a regulatory framework (Basic Safety Rule, RFS III.2.f prescribing that the long-term geological evolution be taken into account to assess the dynamics of radionuclide transfers over the very long timescales involved. As a matter of fact, the period in the future is in the order of 1 million years and is consistent with the timescales of geological evolutions likely to be significant, especially at ground surface, due to fast and high-amplitude climate variations. In order to achieve that goal, external and internal geodynamic phenomena that would generate the potential evolution are studied both on the surface and deep underground. The purpose is to define a reference scenario where the evolution of the environment is induced by a series of very likely natural events in the future. In such a framework, the basis of the approach is to continue studying the geological evolution together with past situation analogies. The work also involves the description of one or several possible variations, such as potential extreme variations or disturbances of the evolution due to the impact of human activities. That aspect is particularly important with regard to the climate evolution, because of the hypotheses on the long-term effects of greenhouse gases. In that context, the goal is to forecast potential exceptional situations in the future with or without similar conditions in the past. (author)

A spatial database of bedding attitudes to accompany Geologic map of the greater Denver area, Front Range Urban Corridor, Colorado

Science.gov (United States)

Trimble, Donald E.; Machette, Michael N.; Brandt, Theodore R.; Moore, David W.; Murray, Kyle E.

2003-01-01

This digital map shows bedding attitude symbols display over the geographic extent of surficial deposits and rock stratigraphic units (formations) as compiled by Trimble and Machette 1973-1977 and published in 1979 (U.S. Geological Survey Map I-856-H) under the Front Range Urban Corridor Geology Program. Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes. A convenient feature of the compiled map is its uniform classification of geologic units that mostly matches those of companion maps to the north (USGS I-855-G) and to the south (USGS I-857-F). Published as a color paper map, the Trimble and Machette map was intended for land-use planning in the Front Range Urban Corridor. This map recently (1997-1999), was digitized under the USGS Front Range Infrastructure Resources Project (see cross-reference). In general, the mountainous areas in the west part of the map exhibit various igneous and metamorphic bedrock units of Precambrian age, major faults, and fault brecciation zones at the east margin (5-20 km wide) of the Front Range. The eastern and central parts of the map (Colorado Piedmont) depict a mantle of unconsolidated deposits of Quaternary age and interspersed outcroppings of Cretaceous or Tertiary-Cretaceous sedimentary bedrock. The Quaternary mantle is comprised of eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone, shale, and limestone bedrock formations form hogbacks and intervening valleys.

Adaptive dynamics on an environmental gradient that changes over a geological time-scale.

Science.gov (United States)

Fortelius, Mikael; Geritz, Stefan; Gyllenberg, Mats; Toivonen, Jaakko

2015-07-07

The standard adaptive dynamics framework assumes two timescales, i.e. fast population dynamics and slow evolutionary dynamics. We further assume a third timescale, which is even slower than the evolutionary timescale. We call this the geological timescale and we assume that slow climatic change occurs within this timescale. We study the evolution of our model population over this very slow geological timescale with bifurcation plots of the standard adaptive dynamics framework. The bifurcation parameter being varied describes the abiotic environment that changes over the geological timescale. We construct evolutionary trees over the geological timescale and observe both gradual phenotypic evolution and punctuated branching events. We concur with the established notion that branching of a monomorphic population on an environmental gradient only happens when the gradient is not too shallow and not too steep. However, we show that evolution within the habitat can produce polymorphic populations that inhabit steep gradients. What is necessary is that the environmental gradient at some point in time is such that the initial branching of the monomorphic population can occur. We also find that phenotypes adapted to environments in the middle of the existing environmental range are more likely to branch than phenotypes adapted to extreme environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geological, radiometrical, and geochemical studies of Banggai granites and Bobong formation to determine potential Uranium area in Taliabu Island, North Maluku

International Nuclear Information System (INIS)

Ngadenin

2016-01-01

Geological, radiometrical, and geochemical studies of Banggai granites and Bobong Formation have been conducted in order to obtain potential uranium area. Taliabu Island is selected for the study because Taliabu Island is a micro continent fraction of the Gondwana super continent that separated at the end of the Mesozoic to Paleogene period. Some types of uranium mineralization formed in the period of Gondwana include sandstone-type, lignite coal type, and vein-type. Taliabu Island is a small part from the Gondwana super continent so it is expected will be found uranium mineralization or at least indications of uranium mineralization occurrences. The aim of this study is to obtain uranium potential areas for the development of uranium exploration in the future. The methods used are reviewing geological, radiometric, and geochemical data from various sources. The results of review showed that geological setting, radiometric, and geochemical data gives positive indication to the formation of uranium mineralization for sandstone type. Banggai granite is a potential uranium source. Sandstone of Bobong Formation as a potential host rock. Coal and pyrite as a potential precipitant. Uranium potential area is located on Bobong Formation and its surrounding. (author)

Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage.

Directory of Open Access Journals (Sweden)

Roger B J Benson

2014-05-01

Full Text Available Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large

Lunar and Planetary Geology

Science.gov (United States)

Basilevsky, Alexander T.

2018-05-01

Lunar and planetary geology can be described using examples such as the geology of Earth (as the reference case) and geologies of the Earth's satellite the Moon; the planets Mercury, Mars and Venus; the satellite of Saturn Enceladus; the small stony asteroid Eros; and the nucleus of the comet 67P Churyumov-Gerasimenko. Each body considered is illustrated by its global view, with information given as to its position in the solar system, size, surface, environment including gravity acceleration and properties of its atmosphere if it is present, typical landforms and processes forming them, materials composing these landforms, information on internal structure of the body, stages of its geologic evolution in the form of stratigraphic scale, and estimates of the absolute ages of the stratigraphic units. Information about one body may be applied to another body and this, in particular, has led to the discovery of the existence of heavy "meteoritic" bombardment in the early history of the solar system, which should also significantly affect Earth. It has been shown that volcanism and large-scale tectonics may have not only been an internal source of energy in the form of radiogenic decay of potassium, uranium and thorium, but also an external source in the form of gravity tugging caused by attractions of the neighboring bodies. The knowledge gained by lunar and planetary geology is important for planning and managing space missions and for the practical exploration of other bodies of the solar system and establishing manned outposts on them.

The features of the isotope composition of carbon in the Paleozoic and Mesozoic oils of Western Siberia

Energy Technology Data Exchange (ETDEWEB)

Golyshev, S.I.; Lebedena, L.V.

1984-01-01

The isotope composition of the carbon in the oils from the Mesozoic and Paleozoic deposits is measured. The variations in the isotope composition of carbon for the Paleozoic oils is between 27.5 and 30.8 percent, while for the oils from the lower Jurassic and Triassic levels it is between 27.7 and 31.2 percent and for the upper Jurassic oils it is between 30.1 and 34.5 percent. The dependence of the isotope composition of the carbon in the oils on the type of original organic matter and its metamorphosis conditions during lithogenesis is analyzed. A softening in the isotope composition of the carbon in the oils from the oceanic deposits relative to continental deposits is found, together with a genetic individualism of the oils from the Paleozoic deposits and their difference from the oils in the Mesozoic deposits.

Geology and geochemistry of the Atacama Desert.

Science.gov (United States)

Tapia, J; González, R; Townley, B; Oliveros, V; Álvarez, F; Aguilar, G; Menzies, A; Calderón, M

2018-02-14

The Atacama Desert, the driest of its kind on Earth, hosts a number of unique geological and geochemical features that make it unlike any other environment on the planet. Considering its location on the western border of South America, between 17 and 28 °S, its climate has been characterized as arid to hyperarid for at least the past 10 million years. Notably dry climatic conditions of the Atacama Desert have been related to uplift of the Andes and are believed to have played an important role in the development of the most distinctive features of this desert, including: (i) nitrates and iodine deposits in the Central Depression, (ii) secondary enrichment in porphyry copper deposits in the Precordillera, (iii) Li enrichment in salt flats of the Altiplano, and (iv) life in extreme habitats. The geology and physiography of the Atacama Desert have been largely shaped by the convergent margin present since the Mesozoic era. The geochemistry of surface materials is related to rock geochemistry (Co, Cr, Fe, Mn, V, and Zn), salt flats, and evaporite compositions in endorheic basins (As, B, and Li), in addition to anthropogenic activities (Cu, Mo, and Pb). The composition of surface water is highly variable, nonetheless in general it presents a circumneutral pH with higher conductivity and total dissolved solids in brines. Major water constituents, with the exception of HCO 3 - , are generally related to the increase of salinity, and despite the fact that trace elements are not well-documented, surface waters of the Atacama Desert are enriched in As, B, and Li when compared to the average respective concentrations in rivers worldwide.

Development of methodology to construct a generic conceptual model of river-valley evolution for performance assessment of HLW geological disposal

International Nuclear Information System (INIS)

Kawamura, Makoto; Tanikawa, Shin-ichi; Yasue, Ken-ichi; Niizato, Tadafumi

2011-01-01

In order to assess the long-term safety of a geological disposal system for high-level radioactive waste (HLW), it is important to consider the impact of uplift and erosion, which cannot be precluded on a timescale in the order of several hundred thousand years for many locations in Japan. Geomorphic evolution, caused by uplift and erosion and coupled to climatic and sea-level changes, will impact the geological disposal system due to resulting spatial and temporal changes in the disposal environment. Degradation of HLW barrier performance will be particularly significant when the remnant repository structures near, and are eventually exposed at, the ground surface. In previous studies, fluvial erosion was densified as the key concern in most settings in Japan. Interpretation of the impact of the phenomena at relevant locations in Japan has led to development of a generic conceptual model which contains the features typical at middle reach of rivers. Here, therefore, we present a methodology for development of a generic conceptual model based on best current understanding of fluvial erosion in Japan, which identifies the simplifications and uncertainties involved and assesses their consequences in the context of repository performance. (author)

Sicily in its Mediterranean geological frame

Energy Technology Data Exchange (ETDEWEB)

Broquet, P.

2016-10-01

The Island of Sicily is generally considered to be the geological link between the North African Fold Belt and the Appennines, in Italy. This comes from a cylindristic meaning and is only partly exact. As a matter of fact, Sicily is essentially Greek; Ionian. Up to Middle Cretaceous time, the Sicilian area was a submerged shoal in the sea or the Panormide area, bordering the Ionian Ocean. This shoal lay between the future North African Fold Belt and the Appennines, forming an intermediate link between the Appenninic, Apulian, Panormian and Tunisian platforms. It was only during the Middle to Upper Cretaceous that the Atlantic and Ligure Oceans merged, making a continuous relationship between the Appenninic, Sicilian and North African sedimentary series. The key time periods are the Permian, Cretaceous and Oligo-Miocene periods leading to the formation of the actual Calabro-Sicilian arc. From the Permian to the present, the Sicilian geological history pertains to three oceanic domains: Ionian, Ligurian and Atlantic, of which the Ionian and Ligurian were under the influence of Tethys (Neo and Paleo-Tethys). The Tethysian identity of Sicily constitutes the major aspect of its geological history. However, the European and African plate tectonic movements complicated its structure. During the Middle Miocene subduction, southern Sicily became African, meanwhile its north-eastern part became, in Pliocene time, Maghrebian by accretion. Sicily is thus a truly geological patchwork, but its main section remains Ionian and now constitutes a link between North Africa and the Appennines. With older data, but also by means of recent results, we will replace Sicily in its Mediterranean frame, giving the mean stages of its paleogeographical and then its tectonic evolution. We will review the calabro-sicilian arc evolution from the Oligocene, developing the actual context and recalling the main fundamental play of the Numidian flysch. (Author)

Plant water use efficiency over geological time--evolution of leaf stomata configurations affecting plant gas exchange.

Science.gov (United States)

Assouline, Shmuel; Or, Dani

2013-01-01

Plant gas exchange is a key process shaping global hydrological and carbon cycles and is often characterized by plant water use efficiency (WUE - the ratio of CO2 gain to water vapor loss). Plant fossil record suggests that plant adaptation to changing atmospheric CO2 involved correlated evolution of stomata density (d) and size (s), and related maximal aperture, amax . We interpreted the fossil record of s and d correlated evolution during the Phanerozoic to quantify impacts on gas conductance affecting plant transpiration, E, and CO2 uptake, A, independently, and consequently, on plant WUE. A shift in stomata configuration from large s-low d to small s-high d in response to decreasing atmospheric CO2 resulted in large changes in plant gas exchange characteristics. The relationships between gas conductance, gws , A and E and maximal relative transpiring leaf area, (amax ⋅d), exhibited hysteretic-like behavior. The new WUE trend derived from independent estimates of A and E differs from established WUE-CO2 trends for atmospheric CO2 concentrations exceeding 1,200 ppm. In contrast with a nearly-linear decrease in WUE with decreasing CO2 obtained by standard methods, the newly estimated WUE trend exhibits remarkably stable values for an extended geologic period during which atmospheric CO2 dropped from 3,500 to 1,200 ppm. Pending additional tests, the findings may affect projected impacts of increased atmospheric CO2 on components of the global hydrological cycle.

A Geological Model for the Evolution of Early Continents (Invited)

Science.gov (United States)

Rey, P. F.; Coltice, N.; Flament, N. E.; Thébaud, N.

2013-12-01

Geochemical probing of ancient sediments (REE in black shales, strontium composition of carbonates, oxygen isotopes in zircons...) suggests that continents were a late Archean addition at Earth's surface. Yet, geochemical probing of ancient basalts reveals that they were extracted from a mantle depleted of its crustal elements early in the Archean. Considerations on surface geology, the early Earth hypsometry and the rheology and density structure of Archean continents can help solve this paradox. Surface geology: The surface geology of Archean cratons is characterized by thick continental flood basalts (CFBs, including greenstones) emplaced on felsic crusts dominated by Trondhjemite-Tonalite-Granodiorite (TTG) granitoids. This simple geology is peculiar because i/ most CFBs were emplaced below sea level, ii/ after their emplacement, CFBs were deformed into relatively narrow, curviplanar belts (greenstone basins) wrapping around migmatitic TTG domes, and iii/ Archean greenstone belts are richly endowed with gold and other metals deposits. Flat Earth hypothesis: From considerations on early Earth continental geotherm and density structure, Rey and Coltice (2008) propose that, because of the increased ability of the lithosphere to flow laterally, orogenic processes in the Archean produced only subdued topography (geology, can be proposed: 1/ Continents appeared at Earth's surface at an early stage during the Hadean/Archean. However, because they were i/ covered by continental flood basalts, ii/ below sea level, and iii/ deprived of modern-style mountain belts and orogenic plateaux, early felsic

Geologic map of the Big Delta B-2 quadrangle, east-central Alaska

Science.gov (United States)

Day, Warren C.; Aleinikoff, John N.; Roberts, Paul; Smith, Moira; Gamble, Bruce M.; Henning, Mitchell W.; Gough, Larry P.; Morath, Laurie C.

2003-01-01

New 1:63,360-scale geologic mapping of the Big Delta B-2 quadrangle provides important data on the structural setting and age of geologic units, as well as on the timing of gold mineralization plutonism within the Yukon-Tanana Upland of east-central Alaska. Gold exploration has remained active throughout the region in response to the discovery of the Pogo gold deposit, which lies within the northwestern part of the quadrangle near the south bank of the Goodpaster River. Geologic mapping and associated geochronological and geochemical studies by the U.S. Geological Survey (USGS) and the Alaska Department of Natural Resources, Division of Mining and Water Management, provide baseline data to help understand the regional geologic framework. Teck Cominco Limited geologists have provided the geologic mapping for the area that overlies the Pogo gold deposit as well as logistical support, which has lead to a much improved and informative product. The Yukon-Tanana Upland lies within the Tintina province in Alaska and consists of Paleozoic and possibly older(?) supracrustal rocks intruded by Paleozoic (Devonian to Mississippian) and Cretaceous plutons. The oldest rocks in the Big Delta B-2 quadrangle are Paleozoic gneisses of both plutonic and sedimentary origin. Paleozoic deformation, potentially associated with plutonism, was obscured by intense Mesozoic deformation and metamorphism. At least some of the rocks in the quadrangle underwent tectonism during the Middle Jurassic (about 188 Ma), and were subsequently deformed in an Early Cretaceous contractional event between about 130 and 116 Ma. New U-Pb SHRIMP data presented here on zircons from the Paleozoic biotite gneisses record inherited cores that range from 363 Ma to about 2,130 Ma and have rims of euhedral Early Cretaceous metamorphic overgrowths (116 +/- 4 Ma), interpreted to record recrystallization during Cretaceous west-northwest-directed thrusting and folding. U-Pb SHRIMP dating of monazite from a Paleozoic

Geological-genetic classification for uranium deposits

International Nuclear Information System (INIS)

Terentiev, V.M.; Naumov, S.S.

1997-01-01

The paper describes a system for classification uranium deposits based on geological and genetic characteristics. The system is based on the interrelation and interdependence of uranium ore formation processes and other geological phenomena including sedimentation, magmatism and tectonics, as well as the evolution of geotectonic structures. Using these aspects, deposits are classified in three categories: endogenic - predominately hydrothermal and hydrothermal-metasomatic; exogenic - sedimentary diagenetic, biogenic sorption, and infiltrational; and polygenetic or composite types. The latter complex types includes: sedimentary/metamorphic and metamorphic and sedimentary/hydrothermal, where different ore generating processes have prevailed over a rock unit at different times. The 3 page classification is given in both the English and Russian languages. (author). 3 tabs

Metallogenic geologic conditions and prospecting direction of sandstone type uranium mineralizations in Yili basin of Xinjiang

International Nuclear Information System (INIS)

Chen Daisheng; Wang Ruiying; Li Shengxiang; Zhang Kefang

1994-09-01

Yili basin is a Mesozoic down-warped basin superimposed on the late Paleozoic volcanic taphrogenic basin. Uranium mineralizations are hosted in the Middle-Lower Jurassic coal-bearing series. The depositions environment in the basin is turbulent in the east and relatively stable in the west. It is characterized by coarse-grained sequence with thin thickness in the eastern part and fine-grained with thick thickness in the western part. On the analytical basis of sedimentary facies indices, it is the first time to present a sedimentary model of 'alluvial fan-braided stream-(narrow) lakeshore delta-lacustrine facies and marsh facies' for the coal-bearing series. The authors have summarized the basic geologic features of U-mineralizations in the interlayer oxidation zone, analyzed the difference and cause of U-mineralizations between the south and north, as well as the east and west. The genetic mechanism of U-mineralizations in the basin is discussed. Finally, seven items of geologic prerequisites for the formation of in-situ leachable sandstone type uranium deposits have been suggested and the potential of sandstone type U-mineralizations in the basin has been evaluated. Four promising target areas are selected

Evolution of the global water cycle on Mars: The geological evidence

Science.gov (United States)

Baker, V. R.; Gulick, V. C.

1993-01-01

The geological evidence for active water cycling early in the history of Mars (Noachian geological system or heavy bombardment) consists almost exclusively of fluvial valley networks in the heavily cratered uplands of the planet. It is commonly assumed that these landforms required explanation by atmospheric processes operating above the freezing point of water and at high pressure to allow rainfall and liquid surface runoff. However, it has also been documented that nearly all valley networks probably formed by subsurface outflow and sapping erosion involving groundwater outflow prior to surface-water flow. The prolonged ground-water flow also requires extensive water cycling to maintain hydraulic gradients, but is this done via rainfall recharge, as in terrestrial environments?

Mesozoic carbonate-siliciclastic platform to basin systems of a South Tethyan margin (Egypt, East Mediterranean)

Science.gov (United States)

Tassy, Aurélie; Crouzy, Emmanuel; Gorini, Christian; Rubino, Jean-Loup

2015-04-01

The Mesozoïc Egyptian margin is the south margin of a remnant of the Neo-Tethys Ocean, at the African northern plate boundary. East Mediterranean basin developed during the late Triassic-Early Jurassic rifting with a NW-SE opening direction (Frizon de Lamotte et al., 2011). During Mesozoïc, Egypt margin was a transform margin with a NW-SE orientation of transform faults. In the Eastern Mediterranean basin, Mesozoïc margins are characterized by mixed carbonate-siliciclastics platforms where subsidence and eustacy are the main parameters controlling the facies distribution and geometries of the platform-to-basin transition. Geometries and facies on the platform-slope-basin system, today well constrained on the Levant area, where still poorly known on the Egyptian margin. Geometries and stratigraphic architecture of the Egyptian margin are revealed, thanks to a regional seismic and well data-base provided by an industrial-academic group (GRI, Total). The objective is to understand the sismostratigraphic architecture of the platform-slope-basin system in a key area from Western Desert to Nile delta and Levant margin. Mapping of the top Jurassic and top Cretaceous show seismic geomorphology of the margin, with the cartography of the hinge line from Western Desert to Sinaï. During the Jurassic, carbonate platform show a prograding profile and a distally thickening of the external platform, non-abrupt slope profiles, and palaeovalleys incisions. Since the Cretaceous, the aggrading and retrograding mixed carbonate-siliciclastic platform show an alternation of steep NW-SE oblique segments and distally steepened segments. These structures of the platform edge are strongly controlled by the inherited tethyan transform directions. Along the hinge line, embayments are interpreted as megaslides. The basin infilling is characterised by an alternation of chaotic seismic facies and high amplitude reflectors onlaping the paleoslopes. MTC deposits can mobilize thick sedimentary

Earth's earliest biosphere: Its origin and evolution

International Nuclear Information System (INIS)

Schopf, J.W.

1983-01-01

Some of the subjects discussed are related to the early biogeologic history, the nature of the earth prior to the oldest known rock record, the early earth and the Archean rock record, the prebiotic organic syntheses and the origin of life, Precambrian organic geochemistry, the biochemical evolution of anaerobic energy conversion, the isotopic inferences of ancient biochemistries, Archean stromatolites providing evidence of the earth's earliest benthos, Archean microfossils, the geologic evolution of the Archean-Early Proterozoic earth, and the environmental evolution of the Archean-Early Proterozoic earth. Other topics examined are concerned with geochemical evidence bearing on the origin of aerobiosis, biological and biochemical effects of the development of an aerobic environment, Early Proterozoic microfossils, the evolution of earth's earliest ecosystems, and geographic and geologic data for processed rock samples. Attention is given to a processing procedure for abiotic samples and calculation of model atmospheric compositions, and procedures of organic geochemical analysis

Avalonian crustal controls on basin evolution: implications for the Mesozoic basins of the southern North Sea

Science.gov (United States)

Smit, Jeroen; van Wees, Jan-Diederik; Cloetingh, Sierd

2015-04-01

Little is known of the Southern North Sea Basin's (SNSB) Pre-Permian basement due to a lack of outcrop and cores. The nature and structure of the East Avalonian crust and lithosphere remain even less constrained in the absence of deep seismic (refraction) lines. However, various studies have hinted at the importance of the Reactivation of the Early Carboniferous fault network during each consecutive Mesozoic and Cenozoic tectonic phase, demonstrating the key role of weak zones from the Early Carboniferous structural grain in partitioning of structural deformation and vertical basin motions at various scales. Although the older basin history and the basement attract increasing attention, the Pre-Permian tectonics of the SNSB remains little studied with most attention focused on the Permian and younger history. The strong dispersal of existing constraints requires a comprehensive study from Denmark to the UK, i.e. the East Avalonian microplate, bordered by the Variscan Rheïc suture, the Atlantic and Baltica. Based on an extensive literature study and the reinterpretation of publicly available data, linking constraints from the crust and mantle to stratigraphic-sedimentological information, we complement the map of Early Carboniferous rifting of East Avalonia and propose a new tectonic scenario. From the reinterpretation of the boundary between Avalonia and Baltica we propose a new outline for the Avalonian microplate with implications for the tectonics of the North German Basin. Furthermore, we highlight the nature and extent of the major crustal/lithospheric domains with contrasting structural behaviour and the major boundaries that separate them. Results shed light on the effects of long lived differences in crustal fabric that are responsible for spatial heterogeneity in stress and strain magnitudes and zonations of fracturing, burial history and temperature history. The geomechanical control of large crustal-scale fault structures will provide the constraints

Study of spa and geology in Nagano pref

Energy Technology Data Exchange (ETDEWEB)

Iijima, Namio

1987-03-20

After due consideration of magma activities, spars and the horizontal movement involved in the formation of the Japanese Archipelago, magma generation and plate theory under the Japanese Archipelago were studied comprehensively. Many spars in the Japanese North Alpine mountains, which are located in old rock areas, were mainly gushed out from new-period granite. Thus, they were presumed to be caused by volcanos from Hakuba-Norikura to Ontake. There are also several spas on the Central Upheaval Zone which are new lock area spas. This zone is characterized by focused volcanism which occurred during the time from the Tertiary period to the Quaternary period of the diluival epoch. Especially, the northern part of the zone has many high-temperature spas above 50/sup 0/C. Moreover, at the southern end of this zone, special geological features which prove that the Philippine plate and the Pacific plate are sunk under the Japanese Archipelago were found. It was also estimated that Nagano Prefecture has no spa caused by volcanism of acidic plutonic rocks from the the later Mesozoic era to the early Cenozoic era. (3 figs, 1 tab, 27 refs)

Geochronology and geochemistry of Mesozoic intrusive rocks in the Xing'an Massif of NE China: Implications for the evolution and spatial extent of the Mongol-Okhotsk tectonic regime

Science.gov (United States)

Li, Yu; Xu, Wen-Liang; Tang, Jie; Pei, Fu-Ping; Wang, Feng; Sun, Chen-Yang

2018-04-01

This study presents new zircon U-Pb-Hf and whole-rock geochemical data for intrusive rocks in the Xing'an Massif of NE China, with the aim of furthering our understanding of the evolution and spatial influence of the Mongol-Okhotsk tectonic regime. Zircon U-Pb dating indicates that five stages of Mesozoic magmatism are recorded in the Xing'an Massif, namely during the Middle Triassic ( 237 Ma), the Late Triassic ( 225 Ma), the Early Jurassic ( 178 Ma), the Middle Jurassic ( 168 Ma), and the late Early Cretaceous ( 130 Ma). The Middle Triassic-Early Jurassic intrusive rocks in the Xing'an Massif are dominantly granodiorites, monzogranites, and syenogranites that formed from magma generated by partial melting of newly accreted continental crust. Geochemistry of the Middle Triassic-Early Jurassic granitoid suites of the Xing'an Massif indicates their formation at an active continental margin setting, related to the southwards subduction of the Mongol-Okhotsk oceanic plate. The Middle Jurassic monzogranites in the Xing'an Massif are geochemically similar to adakites and have εHf(t) values (+3.8 to +5.8) and Hf two-stage model ages (TDM2; 979-850 Ma) that are indicative of derivation from magma generated by partial melting of thickened juvenile lower crust. The Middle Jurassic monzogranites formed in a compressional setting related to the closure of the Mongol-Okhotsk Ocean. The late Early Cretaceous intrusive rocks in the Xing'an Massif are dominated by A-type granitoids that are associated with bimodal volcanic rocks, suggesting their formation in an extensional environment related to either (i) delamination of a previously thickened region of the crust, associated with the Mongol-Okhotsk tectonic regime; (ii) the subduction of the Paleo-Pacific Plate; or (iii) the combined influence of these two tectonic regimes.

Late-Paleozoic-Mesozoic deformational and deformation related metamorphic structures of Kuznetsk-Altai region

Science.gov (United States)

Zinoviev, Sergei

2014-05-01

Kuznetsk-Altai region is a part of the Central Asian Orogenic Belt. The nature and formation mechanisms of the observed structure of Kuznetsk-Altai region are interpreted by the author as the consequence of convergence of Tuva-Mongolian and Junggar lithospheric block structures and energy of collision interaction between the blocks of crust in Late-Paleozoic-Mesozoic period. Tectonic zoning of Kuznetsk-Altai region is based on the principle of adequate description of geological medium (without methods of 'primary' state recovery). The initial indication of this convergence is the crust thickening in the zone of collision. On the surface the mechanisms of lateral compression form a regional elevation; with this elevation growth the 'mountain roots' start growing. With an approach of blocks an interblock elevation is divided into various fragments, and these fragments interact in the manner of collision. The physical expression of collision mechanisms are periodic pulses of seismic activity. The main tectonic consequence of the block convergence and collision of interblock units is formation of an ensemble of regional structures of the deformation type on the basis of previous 'pre-collision' geological substratum [Chikov et al., 2012]. This ensemble includes: 1) allochthonous and autochthonous blocks of weakly deformed substratum; 2) folded (folded-thrust) systems; 3) dynamic metamorphism zones of regional shears and main faults. Characteristic of the main structures includes: the position of sedimentary, magmatic and PT-metamorphic rocks, the degree of rock dynamometamorphism and variety rock body deformation, as well as the styles and concentrations of mechanic deformations. 1) block terranes have weakly elongated or isometric shape in plane, and they are the systems of block structures of pre-collision substratum separated by the younger zones of interblock deformations. They stand out among the main deformation systems, and the smallest are included into the

Integrated elemental and Sr-Nd-Pb-Hf isotopic studies of Mesozoic mafic dykes from the eastern North China Craton: implications for the dramatic transformation of lithospheric mantle

Science.gov (United States)

Liu, Shen; Feng, Caixia; Santosh, M.; Feng, Guangying; Coulson, Ian M.; Xu, Mengjing; Guo, Zhuang; Guo, Xiaolei; Peng, Hao; Feng, Qiang

2018-02-01

Evolution of the lithospheric mantle beneath the North China Craton (NCC) from its Precambrian cratonic architecture until Paleozoic, and the transformation to an oceanic realm during Mesozoic, with implications on the destruction of cratonic root have attracted global attention. Here we present geochemical and isotopic data on a suite of newly identified Mesozoic mafic dyke swarms from the Longwangmiao, Weijiazhuang, Mengjiazhuang, Jiayou, Huangmi, and Xiahonghe areas (Qianhuai Block) along the eastern NCC with an attempt to gain further insights on the lithospheric evolution of the region. The Longwangmiao dykes are alkaline with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N > 4.3) and EM1-like Sr-Nd-Pb-Hf isotopic signature ((87Sr/86Sr) i > 0.706; ε Nd (t) 16.6, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.8, ε Hf (t) 3.7), and display similar EM1-like isotopic features ((87Sr/86Sr) i > 0.706; ε Nd (t) 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) 2.4) and EM1-like isotopic features((87Sr/86Sr) i > 0.706; ε Nd (t) 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) 3.7) and EM1-like Sr-Nd-Pb-Hf isotopic features ((87Sr/86Sr) i > 0.706; ε Nd(t) 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) 9.3) and EM1-like isotopic composition ((87Sr/86Sr) i > 0.705; ε Nd (t) 16.9, (207Pb/204Pb) i > 15.5, (208Pb/204Pb) i > 36.9, ε Hf (t) 0.705; ε Nd (t) 16.9, (207Pb/204Pb) i > 15.5, (208Pb/204Pb) i > 36.9, ε Hf (t) < -8.6). Our data from the various mafic dyke suites suggest that the magmas were derived from EM1-like lithospheric mantle, corresponding to lithospheric mantle modified by the previously foundered lower crust beneath the eastern NCC. Our results suggest contrasting lithospheric evolution from Triassic (212 Ma) to Cretaceous (123 Ma) beneath the NCC. These mafic dykes mark an important phase of lithospheric thinning in the eastern North China Craton.

Strontium and oxygen isotopic variations in mesozoic and tertiary plutons of central Idaho

International Nuclear Information System (INIS)

Fleck, R.J.; Criss, R.E.

1985-01-01

Regional variations in initial 87 Sr/ 86 Sr ratios (rsub(i)) of Mesozoic plutons in central Idaho locate the edge of Precambrian continental crust at the boundary between the late Paleozoic-Mesozoic accreted terranes and Precambrian sialic crust in western Idaho. The rsub(i) values increase abruptly but continuously from less than 0.704 in the accreted terranes to greater than 0.708 across a narrow, 5 to 15 km zone, characterized by elongate, lens-shaped, highly deformed plutons and schistose metasedimentary and metavolcanic units. The chemical and petrologic character of the plutons changes concomitantly from ocean-arc-type units to a weakly peraluminous, calcit to calcalkalic suite. Plutons in both suites yield Late Cretaceous ages, but Permian through Early Cretaceous bodies are confined to the accreted terranes and early Tertiary intrusions are restricted to areas underlain by Precambrian crust. The two major terranes were juxtaposed between 75 and 130 m.y. ago, probably between 80 and 95 m.y. Oxygen and strontium isotopic ratios and Rb and Sr concentrations of the plutonic rocks document a significant upper-crustal contribution to the magmas that intrude Precambrian crust. Magmas intruding the arc terranes were derived from the upper mantle/subducted oceanic lithosphere and may have been modified by anatexis of earlier island-arc volcanic and sedimentary units. (orig./PW)

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2001-09-14

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 1 of the project has been reservoir description and characterization. This effort has included four tasks: (1) geoscientific reservoir characterization, (2) the study of rock-fluid interactions, (3) petrophysical and engineering characterization and (4) data integration. This work was scheduled for completion in Year 1. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions has been initiated. Observations regarding the diagenetic processes influencing pore system development and heterogeneity in these reef and shoal reservoirs have been

Contribution of the geology and geochemistry modelling to the petroleum industry

International Nuclear Information System (INIS)

Tissot, B.

1993-01-01

Evolution of modelling and model interpretation in the domain of geology, geophysics and geochemistry applied to petroleum industry, is first summarized. Hydrocarbon geological formation modelling is then presented in details with examples of kinetic models such as the discrete distribution and the Gaussian distribution based models, and the kerogene to petroleum process modelling. Petroleum basin modelling is also discussed with methods such as back-stripping, conductive thermal transfers, etc. 14 figs., 26 refs

A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny.

Science.gov (United States)

Scheyer, Torsten M; Neenan, James M; Bodogan, Timea; Furrer, Heinz; Obrist, Christian; Plamondon, Mathieu

2017-06-30

Recently it was suggested that the phylogenetic clustering of Mesozoic marine reptile lineages, such as thalattosaurs, the very successful fish-shaped ichthyosaurs and sauropterygians (including plesiosaurs), among others, in a so-called 'superclade' is an artefact linked to convergent evolution of morphological characters associated with a shared marine lifestyle. Accordingly, partial 'un-scoring' of the problematic phylogenetic characters was proposed. Here we report a new, exceptionally preserved and mostly articulated juvenile skeleton of the diapsid reptile, Eusaurosphargis dalsassoi, a species previously recovered within the marine reptile 'superclade', for which we now provide a revised diagnosis. Using micro-computed tomography, we show that besides having a deep skull with a short and broad rostrum, the most outstanding feature of the new specimen is extensive, complex body armour, mostly preserved in situ, along its vertebrae, ribs, and forelimbs, as well as a row of flat, keeled ventrolateral osteoderms associated with the gastralia. As a whole, the anatomical features support an essentially terrestrial lifestyle of the animal. A review of the proposed partial character 'un-scoring' using three published data matrices indicate that this approach is flawed and should be avoided, and that within the marine reptile 'superclade' E. dalsassoi potentially is the sister taxon of Sauropterygia.

The molecular origin and evolution of dim-light vision in mammals.

Science.gov (United States)

Bickelmann, Constanze; Morrow, James M; Du, Jing; Schott, Ryan K; van Hazel, Ilke; Lim, Steve; Müller, Johannes; Chang, Belinda S W

2015-11-01

The nocturnal origin of mammals is a longstanding hypothesis that is considered instrumental for the evolution of endothermy, a potential key innovation in this successful clade. This hypothesis is primarily based on indirect anatomical inference from fossils. Here, we reconstruct the evolutionary history of rhodopsin--the vertebrate visual pigment mediating the first step in phototransduction at low-light levels--via codon-based model tests for selection, combined with gene resurrection methods that allow for the study of ancient proteins. Rhodopsin coding sequences were reconstructed for three key nodes: Amniota, Mammalia, and Theria. When expressed in vitro, all sequences generated stable visual pigments with λMAX values similar to the well-studied bovine rhodopsin. Retinal release rates of mammalian and therian ancestral rhodopsins, measured via fluorescence spectroscopy, were significantly slower than those of the amniote ancestor, indicating altered molecular function possibly related to nocturnality. Positive selection along the therian branch suggests adaptive evolution in rhodopsin concurrent with therian ecological diversification events during the Mesozoic that allowed for an exploration of the environment at varying light levels. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Tracing the evolution of avian wing digits.

Science.gov (United States)

Xu, Xing; Mackem, Susan

2013-06-17

It is widely accepted that birds are a subgroup of dinosaurs, but there is an apparent conflict: modern birds have been thought to possess only the middle three fingers (digits II-III-IV) of an idealized five-digit tetrapod hand based on embryological data, but their Mesozoic tetanuran dinosaur ancestors are considered to have the first three digits (I-II-III) based on fossil evidence. How could such an evolutionary quirk arise? Various hypotheses have been proposed to resolve this paradox. Adding to the confusion, some recent developmental studies support a I-II-III designation for avian wing digits whereas some recent paleontological data are consistent with a II-III-IV identification of the Mesozoic tetanuran digits. A comprehensive analysis of both paleontological and developmental data suggests that the evolution of the avian wing digits may have been driven by homeotic transformations of digit identity, which are more likely to have occurred in a partial and piecemeal manner. Additionally, recent genetic studies in mouse models showing plausible mechanisms for central digit loss invite consideration of new alternative possibilities (I-II-IV or I-III-IV) for the homologies of avian wing digits. While much progress has been made, some advances point to the complexity of the problem and a final resolution to this ongoing debate demands additional work from both paleontological and developmental perspectives, which will surely yield new insights on mechanisms of evolutionary adaptation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Geological Mapping of the Lada Terra (V-56) Quadrangle, Venus

Science.gov (United States)

Kumar, P. Senthil; Head, James W., III

2009-01-01

Geological mapping of the V-56 quadrangle (Fig. 1) reveals various tectonic and volcanic features and processes in Lada Terra that consist of tesserae, regional extensional belts, coronae, volcanic plains and impact craters. This study aims to map the spatial distribution of different material units, deformational features or lineament patterns and impact crater materials. In addition, we also establish the relative age relationships (e.g., overlapping or cross-cutting relationship) between them, in order to reconstruct the geologic history. Basically, this quadrangle addresses how coronae evolved in association with regional extensional belts, in addition to evolution of tesserae, regional plains and impact craters, which are also significant geological units of Lada Terra.

The Evolution and Extinction of the Dinosaurs

Science.gov (United States)

Fastovsky, David E.; Weishampel, David B.

2005-02-01

Written for non-specialists, this detailed survey of dinosaur origins, diversity, and extinction is designed as a series of successive essays covering important and timely topics in dinosaur paleobiology, such as "warm-bloodedness," birds as living dinosaurs, the new, non-flying feathered dinosaurs, dinosaur functional morphology, and cladistic methods in systematics. Its explicitly phylogenetic approach to the group is that taken by dinosaur specialists. The book is not an edited compilation of the works of many individuals, but a unique, cohesive perspective on Dinosauria. Lavishly illustrated with hundreds of new, specially commissioned illustrations by John Sibbick, world-famous illustrator of dinosaurs, the volume includes multi-page drawings as well as sketches and diagrams. First edition Hb (1996): 0-521-44496-9 David E. Fastovsky is Professor of Geosciences at the University of Rhode Island. Fastovsky, the author of numerous scientific publications dealing with Mesozoic vertebrate faunas and their ancient environments, is also scientific co-Editor of Geology. He has undertaken extensive fieldwork studying dinosaurs and their environments in Montana, North Dakota, Arizona, Mexico, and Mongolia. David B. Weishampel is a professor at the Center for Functional Anatomy and Evolution at Johns Hopkins University, School of Medicine. Weishampel is best known for discovering, researching, and naming several rare European dinosaur species. During the 1980s Weishampel gained fame for his work with American paleontologist Jack Horner and later named the famous plant-eating, egg-laying Orodromeus, Horner. Now, a decade after his pioneering studies with Horner, Weishampel is most widely known for his current work on the Romanian dinosaur fauna. He is the author and co-author of many titles, including The Dinosaur Papers, 1676-1906 (Norton, 2003); The Dinosauria, (University of California, 1990); and Dinosaurs of the East Coast, (Johns Hopkins University Press, 1996).

Diversity of developmental patterns in achelate lobsters-today and in the Mesozoic.

Science.gov (United States)

Haug, Joachim T; Audo, Denis; Charbonnier, Sylvain; Haug, Carolin

2013-11-01

Modern achelate lobsters, slipper and spiny lobsters, have a specific post-embryonic developmental pattern with the following phases: phyllosoma, nisto (slipper lobsters) or puerulus (spiny lobsters), juvenile and adult. The phyllosoma is a peculiar larva, which transforms through a metamorphic moult into another larval form, the nisto or puerulus which largely resembles the juvenile. Unlike the nisto and puerulus, the phyllosoma is characterised by numerous morphological differences to the adult, e.g. a thin head shield, elongate appendages, exopods on these appendages and a special claw. Our reinvestigation of the 85 million years old fossil "Eryoneicus sahelalmae" demonstrates that it represents an unusual type of achelatan lobster larva, characterised by a mixture of phyllosoma and post-phyllosoma characters. We ascribe it to its own genus: Polzicaris nov. gen. We study its significance by comparisons with other cases of Mesozoic fossil larvae also characterised by a mixture of characters. Accordingly, all these larvae are interpreted as ontogenetic intermediates between phyllosoma and post-phyllosoma morphology. Remarkably, most of the larvae show a unique mixture of retained larval and already developed post-larval features. Considering the different-and incompatible-mixture of characters of each of these larvae and their wide geographical and temporal distribution, we interpret all these larvae as belonging to distinct species. The particular character combinations in the different larvae make it currently difficult to reconstruct an evolutionary scenario with a stepwise character acquisition. Yet, it can be concluded that a larger diversity of larval forms and developmental patterns occurred in Mesozoic than in modern faunas.

The application of geological computer modelling systems to the characterisation and assessment of radioactive waste repositories

International Nuclear Information System (INIS)

White, M.J.; Del Olmo, C.

1996-01-01

The deep disposal of radioactive waste requires the collection and analysis of large amounts of geological data. These data give information on the geological and hydrogeological setting of repositories and research sites, including the geological structure and the nature of the groundwater. The collection of these data is required in order to develop an understanding of the geology and the geological evolution of sites and to provide quantitative information for performance assessments. An integrated approach to the interpretation and provision of these data is proposed in this paper, via the use of computer systems, here termed geological modelling systems. Geological modelling systems are families of software programmes which allow the incorporation of site investigation data into integrated 3D models of sub-surface geology

Geology of Libya Montes and the Interbasin Plains of Northern Tyrrhena Terra, Mars: Project Introduction and First Year Work Plan

Science.gov (United States)

Skiner, J. A., Jr.; Rogers, A. D.; Seelos, K. D.

2009-01-01

The highland-lowland boundary (HLB) of Mars is interpreted to be a complex tectonic and erosional transition that may hold evidence for past geologic processes and environments. The HLB-abutting margin of the Libya Montes and the interbasin plains of northern Tyrrhena Terra display an exceptional view of the earliest to middle history of Mars that has yet to be fully characterized. This region contains some of the oldest exposed materials on the Martian surface as well as aqueous mineral signatures that may be potential chemical artifacts of early highland formational processes. However, a full understanding of the regions geologic and stratigraphic evolution is remarkably lacking. Some outstanding questions regarding the geologic evolution of Libya Montes and northern Tyrrhena Terra in-clude: Does combining geomorphology and composition advance our understanding of the region s evolution? Can highland materials be subdivided into stratigraphically discrete rock and sediment sequences? What do major physiographic transitions imply about the balanced tectonism, climate change, and erosion? Where is the erosional origin and what is the post-depositional history of channel and plains units? When and in what types of environments did aqueous mineral signatures arise? This abstract introduces the geologic setting, science rationale, and first year work plan of a recently-funded 4-year geologic mapping proposal (project year = calendar year). The objective is to delineate the geologic evolution of Libya Montes and northern Tyrrhena Terra at 1:1M scale using both classical geomorphological and compositional mapping techniques. The funded quadrangles are MTMs 00282, -05282, -10282, 00277, -05277, and -10277.

The geologic history of Margaritifer basin, Mars

Science.gov (United States)

Salvatore, M. R.; Kraft, M. D.; Edwards, Christopher; Christensen, P.R.

2016-01-01

In this study, we investigate the fluvial, sedimentary, and volcanic history of Margaritifer basin and the Uzboi-Ladon-Morava (ULM) outflow channel system. This network of valleys and basins spans more than 8000 km in length, linking the fluvially dissected southern highlands and Argyre Basin with the northern lowlands via Ares Vallis. Compositionally, thermophysically, and morphologically distinct geologic units are identified and are used to place critical relative stratigraphic constraints on the timing of geologic processes in Margaritifer basin. Our analyses show that fluvial activity was separated in time by significant episodes of geologic activity, including the widespread volcanic resurfacing of Margaritifer basin and the formation of chaos terrain. The most recent fluvial activity within Margaritifer basin appears to terminate at a region of chaos terrain, suggesting possible communication between surface and subsurface water reservoirs. We conclude with a discussion of the implications of these observations on our current knowledge of Martian hydrologic evolution in this important region.

Geology of Southern Quintana Roo (Mexico) and the Chicxulub Ejecta Blanket

Science.gov (United States)

Schönian, F.; Tagle, R.; Stöffler, D.; Kenkmann, T.

2005-03-01

In southern Quintana Roo (Mexico) the Chicxulub ejecta blanket is discontinuously filling a karstified pre-KT land surface. This suggests a completely new scenario for the geological evolution of the southern Yucatán Peninsula.

Astronomical calibration of the geological timescale: closing the middle Eocene gap

Science.gov (United States)

Westerhold, T.; Röhl, U.; Frederichs, T.; Bohaty, S. M.; Zachos, J. C.

2015-09-01

To explore cause and consequences of past climate change, very accurate age models such as those provided by the astronomical timescale (ATS) are needed. Beyond 40 million years the accuracy of the ATS critically depends on the correctness of orbital models and radioisotopic dating techniques. Discrepancies in the age dating of sedimentary successions and the lack of suitable records spanning the middle Eocene have prevented development of a continuous astronomically calibrated geological timescale for the entire Cenozoic Era. We now solve this problem by constructing an independent astrochronological stratigraphy based on Earth's stable 405 kyr eccentricity cycle between 41 and 48 million years ago (Ma) with new data from deep-sea sedimentary sequences in the South Atlantic Ocean. This new link completes the Paleogene astronomical timescale and confirms the intercalibration of radioisotopic and astronomical dating methods back through the Paleocene-Eocene Thermal Maximum (PETM, 55.930 Ma) and the Cretaceous-Paleogene boundary (66.022 Ma). Coupling of the Paleogene 405 kyr cyclostratigraphic frameworks across the middle Eocene further paves the way for extending the ATS into the Mesozoic.

Nagra technical report 14-02, geological basics - Dossier II - Sediments and tectonic considerations; SGT Etappe 2: Vorschlag weiter zu untersuchender geologischer Standortgebiete mit zugehörigen Standortarealen für die Oberflächenanlage -- Geologische Grundlagen -- Dossier II -- Sedimentologische und tektonische Verhältnisse

Energy Technology Data Exchange (ETDEWEB)

Madritsch, H.; Deplazes, G.

2014-12-15

This dossier is the second of a series of eight reports concerning the safety and technical aspects of locations for the disposal of radioactive wastes in Switzerland. It considers the sediments that can be used and discusses tectonic considerations. As an introduction, the geological framework is discussed with the various sediments from the Paleozoic, Mesozoic and Cenozoic periods. The various methods used to investigate the rock, such as drilling and reflection-seismic methods along with the investigation of surface formations are discussed. A detailed discussion of the stratigraphic and sedimentological characteristics of the various formations follows. Geological structures and the tectonics in the proposed areas are discussed, as are the depth and thickness of the structures.

Preliminary geologic map of the Black Mountain area northeast of Victorville, San Bernardino County, California

Science.gov (United States)

Stone, Paul

2006-01-01

The Black Mountain area is in the Mojave Desert about 20 km northeast of Victorville, California. The geology of this area is of interest primarily for its excellent exposures of the early Mesozoic Fairview Valley Formation, a sequence of weakly metamorphosed sedimentary rocks including a thick, commercially important unit of limestone conglomerate that has been mined for cement at Black Mountain Quarry for several decades. Recent geochronologic work has shown that the Fairview Valley Formation is probably of Early Jurassic age. This preliminary geologic map of the Black Mountain area depicts the stratigraphic and structural relations of the Fairview Valley Formation and the associated rocks, most notably the overlying Sidewinder Volcanics of Early(?), Middle, and Late(?) Jurassic age. The map is based on new field studies by the author designed to clarify details of the stratigraphy and structure unresolved by previous investigations. The map is considered preliminary because the ages of some geologic units critical for a satisfactory understanding of the stratigraphic and structural framework remain unknown. The map area also includes a segment of the Helendale Fault, one of several faults of known or inferred late Cenozoic right-lateral displacement that make up the Eastern California Shear Zone. The fault is marked by aligned northeast-facing scarps in Pleistocene or older alluvial deposits and the underlying bedrock units. Relations in the map area suggest that right-lateral displacement on the Helendale Fault probably does not exceed 2 km, a conclusion compatible with previous estimates of displacement on this fault based on relations both within and outside the Black Mountain area.

NEA perspectives on timescales and criteria in post-closure safety of geological disposal

International Nuclear Information System (INIS)

Preter, P. de; Smith, P.; Pescatore, C.; Forinash, B.

2006-01-01

A key challenge in the development of safety cases for geological repositories is associated with the long periods of time over which radioactive wastes that are disposed of in repositories remain hazardous. The OECD Nuclear Energy Agency (NEA) has recently examined issues related to timescales in the context of two projects under the auspices of the Radioactive Waste Management Committee (RWMC): the Timescales Initiative and the Long-Term Safety Criteria (LTSC) Initiative. These projects examine, respectively, the treatment of timescales in actual safety cases and in the development of radiological protection criteria for geological disposal. They treat different aspects of timescales but have some overlap and have shown some convergence of the results achieved to date. Based on these projects, this paper examines general considerations in the handling of timescales, including ethical principles, evolution of the hazards of radioactive waste over time, and uncertainty in the evolution of repository systems (including geological features). The implications of these considerations are examined in terms of repository siting; levels of protection in regulations; planning for pre-closure and post-closure actions; and development and presentation of safety cases. A comparison is made with previous NEA work related to timescales, in order to show evolutions in current understanding. (authors)

NEA perspectives on timescales and criteria in post-closure safety of geological disposal

Energy Technology Data Exchange (ETDEWEB)

Preter, P. de [ONDRAF/NIRAS, Brussels (Belgium); Smith, P. [Safety Assessment Management Ltd, SAM Ltd. (United Kingdom); Pescatore, C.; Forinash, B. [OECD/NEA, Nuclear Energy Agency, 92 - Issy les Moulineaux (France)

2006-07-01

A key challenge in the development of safety cases for geological repositories is associated with the long periods of time over which radioactive wastes that are disposed of in repositories remain hazardous. The OECD Nuclear Energy Agency (NEA) has recently examined issues related to timescales in the context of two projects under the auspices of the Radioactive Waste Management Committee (RWMC): the Timescales Initiative and the Long-Term Safety Criteria (LTSC) Initiative. These projects examine, respectively, the treatment of timescales in actual safety cases and in the development of radiological protection criteria for geological disposal. They treat different aspects of timescales but have some overlap and have shown some convergence of the results achieved to date. Based on these projects, this paper examines general considerations in the handling of timescales, including ethical principles, evolution of the hazards of radioactive waste over time, and uncertainty in the evolution of repository systems (including geological features). The implications of these considerations are examined in terms of repository siting; levels of protection in regulations; planning for pre-closure and post-closure actions; and development and presentation of safety cases. A comparison is made with previous NEA work related to timescales, in order to show evolutions in current understanding. (authors)

Continued internal and external research efforts of RAG. New insights for the geological evolution of the Molasse Basin of Austria

Energy Technology Data Exchange (ETDEWEB)

Hinsch, R. [Rohoel-Aufsuchungs AG, Vienna (Austria)

2008-10-23

The understanding of the detailed geological evolution of the Molasse Basin is crucial for the continued success of exploration in this mature basin. Results from several research projects help to find new play types and increase the understanding of stratigraphic traps by characterising the sedimentological processes that control them. Risks associated with play types can be better assessed considering their evolutionary framework. Several studies focussed on that subject have been concluded in recent years or are still ongoing. This presentation will give an overview of the objectives, results and implications of these initiatives for evaluation and analysis of the geological evolution and for exploration of the Molasse Basin. An initial collaboration with Stanford University integrated sedimentological core analyses with 3D seismic, wireline log data interpretation and outcrop studies in analogue settings. The study yielded a modern sedimentological model for the Upper Puchkirchen Formation which was subsequently applied to exploration. A sequence stratigraphic study examined the sequence framework of the Molasse Basin fill and was able to correlate 5 sequences from the shelf into the deep basin. Studies on seismic and core analyses from the south slope of the Puchkirchen trough show how slope morphology and confinement control sediment distribution in the southern slope deposits. The transition from deep to more shallow marine conditions and the progradation of deltaic sequences into the basin in Eggenburgian/Burdigalian times is described by an intense 3-D seismic interpretation in combination with sedimentological core work. Working on a more local scale, other projects are improving the understanding of the detailed architecture of distinct play elements such as the Upper Puchkirchen Channel or the Basal Hall Formation Channel. In general, these studies highlight the complex interaction of processes that control sediment distribution in the basin. Morphology

Paleozoic and mesozoic GIS data from the Geologic Atlas of the Rocky Mountain Region: Volume 1

Science.gov (United States)

Graeber, Aimee; Gunther, Gregory

2017-01-01

The Rocky Mountain Association of Geologists (RMAG) is, once again, publishing portions of the 1972 Geologic Atlas of the Rocky Mountain Region (Mallory, ed., 1972) as a geospatial map and data package. Georeferenced tiff (Geo TIFF) images of map figures from this atlas has served as the basis for these data products. Shapefiles and file geodatabase features have been generated and cartographically represented for select pages from the following chapters:• Phanerozoic Rocks (page 56)• Cambrian System (page 63)• Ordovician System (pages 78 and 79)• Silurian System (pages 87 - 89)• Devonian System (pages 93, 94, and 96 - 98)• Mississippian System (pages 102 and 103)• Pennsylvanian System (pages 114 and 115)• Permian System (pages 146 and 149 - 154)• Triassic System (pages 168 and 169)• Jurassic System (pages 179 and 180)• Cretaceous System (pages 197 - 201, 207 - 210, 215, - 218, 221, 222, 224, 225, and 227).The primary purpose of this publication is to provide regional-scale, as well as local-scale, geospatial data of the Rocky Mountain Region for use in geoscience studies. An important aspect of this interactive map product is that it does not require extensive GIS experience or highly specialized software.

Controls of late Palaeozoic and Mesozoic extension in the British Isles: evidence from seismic reflection data in the Central North Sea

Science.gov (United States)

Smith, K.; Cameron, T. D. J.

2009-04-01

Controls of late Palaeozoic and Mesozoic extension in the British Isles: evidence from seismic reflection data in the Central North Sea. Kevin Smith (1) and Don Cameron (2) (1) British Geological Survey, Murchison House, West Mains Road, Edinburgh, EH9 3LA. (ksm@bgs.ac.uk). (2) British Geological Survey, 376 Gilmerton Road, Edinburgh, EH17 7QS. In the area of the British Isles during the late Devonian and early Carboniferous, the oblique convergence of Laurentia and Gondwana imposed a torque on the adjoining terranes of Baltica and Avalonia. Their resulting clockwise rotation was accommodated by widely distributed N-S extension in the intervening zones previously formed by Caledonian and Acadian convergence. South of Laurentia and Baltica, late Palaeozoic extension was focused (1) at terrane margins, (2) in areas of limited Caledonian-Acadian plutonism, and (3) in places where the western (Iapetus) and eastern (Tornquist) convergence zones intersect at a high angle. One of these latter areas lies in Central England immediately north of the Midland Microcraton (part of Eastern Avalonia), where thermal subsidence associated with early Carboniferous extension gave rise to the late Carboniferous Pennine Basin. Interpretation of an extensive set of 3D and 2D long-offset seismic reflection data suggests that a similar area of enhanced extension at a fold belt intersection lies to north of the Mid North Sea High in the middle of the Central North Sea. Variscan uplift and inversion of the late Palaeozoic basins began to predominate in mid-Carboniferous times as final amalgamation of all the different terranes to form Pangaea curtailed the initial episode of extension and thermal subsidence. This change in the tectonic regime was associated with the onset of tholeiitic volcanism within the convergence zones, and was followed by localised extension during the earliest Permian. Evidence obtained from seismic interpretation of the deep structure of the UK sector of the Central

Planetary Geologic Mapping Handbook - 2009

Science.gov (United States)

Tanaka, K. L.; Skinner, J. A.; Hare, T. M.

2009-01-01

. Terrestrial geologic maps published by the USGS now are primarily digital products using geographic information system (GIS) software and file formats. GIS mapping tools permit easy spatial comparison, generation, importation, manipulation, and analysis of multiple raster image, gridded, and vector data sets. GIS software has also permitted the development of project-specific tools and the sharing of geospatial products among researchers. GIS approaches are now being used in planetary geologic mapping as well (e.g., Hare and others, 2009). Guidelines or handbooks on techniques in planetary geologic mapping have been developed periodically (e.g., Wilhelms, 1972, 1990; Tanaka and others, 1994). As records of the heritage of mapping methods and data, these remain extremely useful guides. However, many of the fundamental aspects of earlier mapping handbooks have evolved significantly, and a comprehensive review of currently accepted mapping methodologies is now warranted. As documented in this handbook, such a review incorporates additional guidelines developed in recent years for planetary geologic mapping by the NASA Planetary Geology and Geophysics (PGG) Program s Planetary Cartography and Geologic Mapping Working Group s (PCGMWG) Geologic Mapping Subcommittee (GEMS) on the selection and use of map bases as well as map preparation, review, publication, and distribution. In light of the current boom in planetary exploration and the ongoing rapid evolution of available data for planetary mapping, this handbook is especially timely.

Directions of the US Geological Survey Landslide Hazards Reduction Program

Science.gov (United States)

Wieczorek, G.F.

1993-01-01

The US Geological Survey (USGS) Landslide Hazards Reduction Program includes studies of landslide process and prediction, landslide susceptibility and risk mapping, landslide recurrence and slope evolution, and research application and technology transfer. Studies of landslide processes have been recently conducted in Virginia, Utah, California, Alaska, and Hawaii, Landslide susceptibility maps provide a very important tool for landslide hazard reduction. The effects of engineering-geologic characteristics of rocks, seismic activity, short and long-term climatic change on landslide recurrence are under study. Detailed measurement of movement and deformation has begun on some active landslides. -from Author

Prospecting ideas for mesozoic granite-type, volcanics-type and exo-contact-type uranium deposits in South China. Pt.1

International Nuclear Information System (INIS)

Yu Dagan

2001-01-01

The Mesozoic uranium ore-formation process in South China resulted from the intense volcanic magmatism, the crust-mantle interaction and the fluidization in Yanshanian period, and there is great prospect for large-scale uranium concentration and ore-formation. Therefore, during the prospecting for Mesozoic granite-type, volcanics-type and exo-contact-type uranium deposits it is necessary to introduce deep-source metallogenic theory, to 'desalt' metallogenic theory of epithermal activation, to fully realize that uranium deposits may be formed not only at shallow depth, but also in conditions of deep-source, great depth and high temperature, as well as in environments of deep-source, shallow depth and median temperature, to give emphasis to the early-stage (130-95 Ma) uranium mineralization, to break the man-made boundary in prospecting for uranium only based on host rock type, to strengthen the research on Cretaceous magmatic system

Uranium potential in outcropping Permian basins in France and their extensions beneath mesozoic and tertiary cover

International Nuclear Information System (INIS)

Hery, B.

1990-01-01

About a third of metropolitan France's uranium production is from Permian deposits located in the Lodeve and, to a lesser extent, Bourbon-l'Archambault basins. Of the Autun, west Vanoise, St-Affrique, Rodez, Brive and Var basins investigated in this study, only those of Rodez and Var have been shown to contain significant deposits. Some of the basins contain potentially interesting targets, often removed from the areas of known mineral occurrences, that have never been investigated. Geophysical exploration and drilling have shown that the Permian extends over a vast area beneath the cover of the large Mesozoic and Tertiary basins. However zones within reach of mineral exploration, ie. those less than 500 m deep, are only found in a few areas. To reach the distant targets down-dip in the outcropping basins or beneath the Mesozoic and Tertiary cover, a detailed study of the basin must be undertaken beforehand. To define and locate targets that are obviously more costly to investigate, direct methods of investigation need to be used such as drilling and geochemistry, and indirect methods such as remote sensing, geophysics and well-logging [fr

Geochemical prerequisites of petroleum-gas formation in the Mesozoic-Cenozoic sedimentary layer of the world's oceans

Energy Technology Data Exchange (ETDEWEB)

Trotsyuk, V Ya

1979-05-01

A summarization is given of the latest material on the geochemistry of trace organic matter of Mesozoic-Cenozoic deposits of the world's oceans, obtained as a result of deep-sea drilling. Trace organic matter was found to be present in the sedimentary layers of the ocean outskirts in amounts near that found in the continental stratosphere, but that content was five times less in the interior region of the oceans. The trace organic matter of deposits in the marginal region of the oceans was found to have a significant petroleum-gas matrix potential with respect to the level of content and composition characteristics. The distribution of organic carbon was found to be uneven in variously aged horizons of the Mesozoic-Cenozoic. The maximum content of organic carbon was noted in the Neogene-Quaternary and lower Cretaceous deposits. An elevated content of trace organic matter was found to be characteristic of the oceanic stratisphere in lithological mixed sediments: terrigenous-carbonate and terrigenous-silicons was 1.5 times greater than the trace organic matter in clays. Fundamental geochemical propagation laws were formulated, possibly for petroleum-gas-bearing sediment basins under the ocean bottom and beyond the shelf. 18 references, 3 figures.

Geologic database for digital geology of California, Nevada, and Utah: an application of the North American Data Model

Science.gov (United States)

Bedford, David R.; Ludington, Steve; Nutt, Constance M.; Stone, Paul A.; Miller, David M.; Miller, Robert J.; Wagner, David L.; Saucedo, George J.

2003-01-01

The USGS is creating an integrated national database for digital state geologic maps that includes stratigraphic, age, and lithologic information. The majority of the conterminous 48 states have digital geologic base maps available, often at scales of 1:500,000. This product is a prototype, and is intended to demonstrate the types of derivative maps that will be possible with the national integrated database. This database permits the creation of a number of types of maps via simple or sophisticated queries, maps that may be useful in a number of areas, including mineral-resource assessment, environmental assessment, and regional tectonic evolution. This database is distributed with three main parts: a Microsoft Access 2000 database containing geologic map attribute data, an Arc/Info (Environmental Systems Research Institute, Redlands, California) Export format file containing points representing designation of stratigraphic regions for the Geologic Map of Utah, and an ArcView 3.2 (Environmental Systems Research Institute, Redlands, California) project containing scripts and dialogs for performing a series of generalization and mineral resource queries. IMPORTANT NOTE: Spatial data for the respective stage geologic maps is not distributed with this report. The digital state geologic maps for the states involved in this report are separate products, and two of them are produced by individual state agencies, which may be legally and/or financially responsible for this data. However, the spatial datasets for maps discussed in this report are available to the public. Questions regarding the distribution, sale, and use of individual state geologic maps should be sent to the respective state agency. We do provide suggestions for obtaining and formatting the spatial data to make it compatible with data in this report. See section ‘Obtaining and Formatting Spatial Data’ in the PDF version of the report.

Characterization by means of geological and geophysical techniques of the hydrogeologic limit between the Guadiana and Jucar watersheds in the Plain of La Mancha, Spain; Caracterizacion de la divisoria hidrogeologica Guadiana-Jucar en la Llanura Manchega mediante tecnicas geologicas y geofisicas

Energy Technology Data Exchange (ETDEWEB)

Lopez Gutierrez, J.; Plata Torres, J. L.; Mejias Moreno, M.

2013-09-01

The characterization of the dividing hydrogeological Guadiana-Jucar (DHGJ) in the Plain of La Mancha, (groundwater dividing line), involves great difficulties, mainly due to the poor outcrop of the Mesozoic and Tertiary formations which constitute major aquifers and the fact of the existence of a broad detrital coating, Plio-Quaternary in age, which prevents the observation of the geological structure. Although the DHGJ in the La Mancha plain has been normally interpreted through piezometric data, this method cannot by itself explain the origin, since the geological structure of the basement is unknown. This work shows the results of the research carried out in this area through gravity and electrical geophysical techniques, and the interpretation of three boreholes drilled in 2010 by the Guadiana River Basin Authority (CHG). The most remarkable result is the absence of any geological threshold in the subsoil, meaning that the hydro-geological divide can only respond to differences in the hydraulic potential within the aquifer. Consequently, the groundwater divide line is subject to spatial variations since the hydraulic head depends on natural and anthropic factors. (Author)

Block Volume Estimation from the Discontinuity Spacing Measurements of Mesozoic Limestone Quarries, Karaburun Peninsula, Turkey

OpenAIRE

Elci, Hakan; Turk, Necdet

2014-01-01

Block volumes are generally estimated by analyzing the discontinuity spacing measurements obtained either from the scan lines placed over the rock exposures or the borehole cores. Discontinuity spacing measurements made at the Mesozoic limestone quarries in Karaburun Peninsula were used to estimate the average block volumes that could be produced from them using the suggested methods in the literature. The Block Quality Designation (BQD) ratio method proposed by the authors has been found to ...

Pyrenean hyper-extension : breaking, thinning, or stretching of the crust ? A view from the central north-Pyrenean zone

Science.gov (United States)

de Saint Blanquat, Michel; Bajolet, Flora; Boulvais, Philippe; Boutin, Alexandre; Clerc, Camille; Delacour, Adélie; Deschamp, Fabien; Ford, Mary; Fourcade, Serge; Gouache, Corentin; Grool, Arjan; Labaume, Pierre; Lagabrielle, Yves; Lahfid, Abdeltif; Lemirre, Baptiste; Monié, Patrick; de Parseval, Philippe; Poujol, Marc

2017-04-01

The geology of the North Pyrenean Zone in the central Pyrenees allows for the observation in the field of the entire section of the Pyrenean rift, from the mantle to the crust and the Mesozoic cover (pre, syn and post rift). The good knowledge we have of the pre-Alpine history of the Pyrenees allows us to properly constrain the Alpine geological evolution of the pre-Triassic rocks which record both Variscan and Alpine orogenic cycles. The mantle outcrop as kilometric to centimetric fragments of peridotite dispersed within a carbonate metamorphic breccia. The study of peridotite serpentinisation shows several events of low-temperature serpentinisation, in contact with seawater. In some locallities, we can observe a mixture of fragments of variously serpentinized peridotites. This suggests a tectonic context where fragments of peridotites from different structural levels were sampled more or less synchronously. The granulitic basement is characterized by a Variscan syndeformational HT event (300-280 Ma). So far we have not found any trace of a Cretaceous HT event (> 500°C). On the other hand, the basement is affected by a regional metasomatism that began during the Jurassic and became more spatially focused with time until it was restricted to the Pyrenean rift during the Aptien, Albian and Cenomanian. The talc-chlorite metasomatism (120-95 Ma) shows an evolution from a static toward a syn-deformation hydrothermal event, under a more or less normal geothermal gradient. Extensional deformation is recorded by the reworking of several inherited low-angle Variscan tectonic contacts, but also by dispersed high-angle extensional shear zones formed under greenshist conditions. The metamorphic Mesozoic cover of the basement massifs, which constitute the so-called Internal Metamorphic Zone, is an allochtonous unit made of lenses of Mesozoic rocks enclosed into the breccia, which locally contains peridotite and basement clasts. The Mesozoic metamorphic carbonates show a first

Geology of the north end of the Salt Valley Anticline, Grand County, Utah

International Nuclear Information System (INIS)

Gard, L.M. Jr.

1976-01-01

The geology and hydrology of a portion of the Salt Valley anticline lying north of Moab, Utah, that is being studied as a potential site for underground storage of nuclear waste in salt are discussed. Selection of this area was based on recommendations made in an earlier appraisal of the potential of Paradox basin salt deposits for such use. Salt Valley anticline, a northwest-trending diapiric structure, consists of Mesozoic sedimentary rocks arched over a thick core of salt of the Paradox Member of the Middle Pennsylvanian Hermosa Formation. Salt began to migrate to form and/or develop this structure shortly after it was deposited, probably in response to faulting. This migration caused upwelling of the salt creating a linear positive area. This positive area, in turn, caused increased deposition of sediments in adjacent areas which further enhanced salt migration. Not until late Jurassic time had flowage of the salt slowed sufficiently to allow sediments of the Morrison and younger formations to be deposited across the salt welt. A thick cap of insoluble residue was formed on top of the salt diapir as a result of salt dissolution through time. The crest of the anticline is breached; it collapsed in two stages during the Tertiary Period. The first stage was graben collapse during the early Tertiary; the second stage occurred after Miocene regional uplift had caused downcutting streams to breach the salt core resulting in further collapse. The axis of the anticline is a narrow generally flat-floored valley containing a few hills composed of downdropped Mesozoic rocks foundered in thecaprock. The caprock, which underlies thin alluvium in the valley, is composed of contorted gypsum, shale, sandstone, and limestone--the insoluble residue of the Paradox salt

Sedimentary facies and depositional environments of early Mesozoic Newark Supergroup basins, eastern North America

Science.gov (United States)

Smoot, J.P.

1991-01-01

The early Mesozoic Newark Supergroup consists of continental sedimentary rocks and basalt flows that occupy a NE-trending belt of elongate basins exposed in eastern North America. The basins were filled over a period of 30-40 m.y. spanning the Late Triassic to Early Jurassic, prior to the opening of the north Atlantic Ocean. The sedimentary rocks are here divided into four principal lithofacies. The alluvial-fan facies includes deposits dominated by: (1) debris flows; (2) shallow braided streams; (3) deeper braided streams (with trough crossbeds); or (4) intense bioturbation or hyperconcentrated flows (tabular, unstratified muddy sandstone). The fluvial facies include deposits of: (1) shallow, ephemeral braided streams; (2) deeper, flashflooding, braided streams (with poor sorting and crossbeds); (3) perennial braided rivers; (4) meandering rivers; (5) meandering streams (with high suspended loads); (6) overbank areas or local flood-plain lakes; or (7) local streams and/or colluvium. The lacustrine facies includes deposits of: (1) deep perennial lakes; (2) shallow perennial lakes; (3) shallow ephemeral lakes; (4) playa dry mudflats; (5) salt-encrusted saline mudflats; or (6) vegetated mudflats. The lake margin clastic facies includes deposits of: (1) birdfoot deltas; (2) stacked Gilbert-type deltas; (3) sheet deltas; (4) wave-reworked alluvial fans; or (5) wave-sorted sand sheets. Coal deposits are present in the lake margin clastic and the lacustrine facies of Carnian age (Late Triassic) only in basins of south-central Virginia and North and South Carolina. Eolian deposits are known only from the basins in Nova Scotia and Connecticut. Evaporites (and their pseudomorphs) occur mainly in the northern basins as deposits of saline soils and less commonly of saline lakes, and some evaporite and alkaline minerals present in the Mesozoic rocks may be a result of later diagenesis. These relationships suggest climatic variations across paleolatitudes, more humid to the

Drawing 1/100,000 scale geological map of Mt. Hakkoda geothermal district

Energy Technology Data Exchange (ETDEWEB)

Muraoka, Hirobumi; Takakura, Shin' ichi

1987-10-01

Geological map of geothermal district of Mt. Hakkoda was made which included the main volcanos created after Pliocene era. For the purpose, geothermal liquid, terrestial heat sources and its storing structures, were studied with consulting geological map. Aerial and satelite photographs were used for the study of faults, foldings, and dikes,. By the result, stratigragic order of layers, developing process of vocanos, and evoluting process of magma, were summarized for report. (5 figs, 4 tabs, 101 refs)

Geologic hazards in the region of the Hurricane fault

Science.gov (United States)

Lund, W.R.

1997-01-01

common in southwestern Utah where it has damaged roads, canal embankments, and water-retention structures. Several unexplained sinkholes near the town of Hurricane possibly are the result of collapse of subsurface volcanic features. Geologic formations associated with slope failures along or near the Hurricane fault include rocks of both Mesozoic and Tertiary age. Numerous landslides are present in these materials along the Hurricane Cliffs, and the Petrified Forest Member of the Chinle Formation is commonly associated with slope failures where it crops out in the St. George Basin. Steep slopes and numerous areas of exposed bedrock make rock fall a hazard in the St. George Basin. Debris flows and debris floods in narrow canyons and on alluvial fans often accompany intense summer cloudburst thunderstorms. Flooded basements and foundation problems associated with shallow ground water are common on benches north of the Santa Clara River in the city of Santa Clara. Stream flooding is the most frequently occurring and destructive geologic hazard in southwestern Utah. Since the 1850s, there have been three major riverine (regional) floods and more than 300 damaging flash floods. Although a variety of flood control measures have been implemented, continued rapid growth in the region is again increasing vulnerability to flood hazards. Site-specific studies to evaluate geologic hazards and identify hazard-reduction measures are recommended prior to construction to reduce the need for costly repair, maintenance, or replacement of improperly placed or protected facilities.

A methodology for scenario development based on understanding of long-term evolution of geological disposal systems

International Nuclear Information System (INIS)

Wakasugi, Keiichiro; Ishiguro, Katsuhiko; Ebashi, Takeshi; Ueda, Hiroyoshi; Koyama, Toshihiro; Shiratsuchi, Hiroshi; Yashio, Shoko; Kawamura, Hideki

2012-01-01

We have developed a 'hybrid' scenario development method by combining bottom-up and top-down approaches and applied for the case of geological disposal of high-level waste. This approach provides a top-down perspective, by introducing a concept of safety functions for different periods and 'storyboards', which depict repository evolution with time on a range of spatial scales, and a bottom-up perspective, by identifying relationship between processes related to radionuclide migration and safety functions based on feature, event and process (FEP) management. Based on a trial study, we have specified work descriptions for each step of the hybrid scenario development methodology and confirmed that the storyboard provides a baseline and holistic overview for the FEP management and a common platform to involve close interaction with experts in various disciplines to understand the crossover phenomenological processes. We also confirmed that there is no conflict between the top-down approach and the bottom-up approach and the hybrid scenario development work frame fulfils the specified requirements for traceability, comprehensiveness, ease of understanding, integration of multidisciplinary knowledge and applicability to a staged approach to siting. (author)

Planetary Geologic Mapping Handbook - 2010. Appendix

Science.gov (United States)

Tanaka, K. L.; Skinner, J. A., Jr.; Hare, T. M.

2010-01-01

the USGS now are primarily digital products using geographic information system (GIS) software and file formats. GIS mapping tools permit easy spatial comparison, generation, importation, manipulation, and analysis of multiple raster image, gridded, and vector data sets. GIS software has also permitted the development of projectspecific tools and the sharing of geospatial products among researchers. GIS approaches are now being used in planetary geologic mapping as well. Guidelines or handbooks on techniques in planetary geologic mapping have been developed periodically. As records of the heritage of mapping methods and data, these remain extremely useful guides. However, many of the fundamental aspects of earlier mapping handbooks have evolved significantly, and a comprehensive review of currently accepted mapping methodologies is now warranted. As documented in this handbook, such a review incorporates additional guidelines developed in recent years for planetary geologic mapping by the NASA Planetary Geology and Geophysics (PGG) Program's Planetary Cartography and Geologic Mapping Working Group's (PCGMWG) Geologic Mapping Subcommittee (GEMS) on the selection and use of map bases as well as map preparation, review, publication, and distribution. In light of the current boom in planetary exploration and the ongoing rapid evolution of available data for planetary mapping, this handbook is especially timely.

Geologic studies in Alaska by the U.S. Geological Survey, 1992

Science.gov (United States)

Dusel-Bacon, Cynthia; Till, Alison B.

1993-01-01

This collection of 19 papers continues the annual series of U.S. Geological Survey reports on the geology of Alaska. The contributions, which include full-length Articles and shorter Geologic Notes, cover a broad range of topics including dune formation, stratigraphy, paleontology, isotopic dating, mineral resources, and tectonics. Articles, grouped under four regional headings, span nearly the entire State from the North Slope to southwestern, south-central, and southeastern Alaska (fig. 1).In the section on northern Alaska, Galloway and Carter use new data on dune morphology and radiocarbon ages from the western Arctic Coastal Plain to develop a late Holocene chronology of multiple episodes of dune stabilization and reactivation for the region. Their study has important implications for climatic changes in northern Alaska during the past 4,000 years. In two papers, Dumoulin and her coauthors describe lithofacies and conodont faunas of Carboniferous strata in the western Brooks Range, discuss depositional environments, and propose possible correlations and source areas for some of the strata. Schenk and Bird propose a preliminary division of the Lower Cretaceous stratigraphic section in the central part of the North Slope into depositional sequences. Aleinikoff and others present new U-Pb data for zircons from metaigneous rocks from the central Brooks Range. Karl and Mull, reacting to a proposal regarding terrane nomenclature for northern Alaska that was published in last year's Alaskan Studies Bulletin, provide a historical perspective of the evolution of terminology for tectonic units in the Brooks Range and present their own recommendations.

Temporal variations in the gene expression levels of cyanobacterial anti-oxidant enzymes through geological history: implications for biological evolution during the Great Oxidation Event

Science.gov (United States)

Harada, M.; Furukawa, R.; Yokobori, S. I.; Tajika, E.; Yamagishi, A.

2016-12-01

A significant rise in atmospheric O2 levels during the GOE (Great Oxidation Event), ca. 2.45-2.0 Ga, must have caused a great stress to biosphere, enforcing life to adapt to oxic conditions. Cyanobacteria, oxygenic photosynthetic bacteria that had been responsible for the GOE, are at the same time one of the organisms that would have been greatly affected by the rise of O2 level in the surface environments. Knowledge on the evolution of cyanobacteria is not only important to elucidate the cause of the GOE, but also helps us to better understand the adaptive evolution of life in response to the GOE. Here we performed phylogenetic analysis of an anti-oxidant enzyme Fe-SOD (iron superoxide dismutase) of cyanobacteria, to assess the adaptive evolution of life under the GOE. The rise of O2 level must have increased the level of toxic reactive oxygen species in cyanobacterial cells, thus forced them to change activities or the gene expression levels of Fe-SOD. In the present study, we focus on the change in the gene expression levels of the enzyme, which can be estimated from the promoter sequences of the gene. Promoters are DNA sequences found upstream of protein encoding regions, where RNA polymerase binds and initiates transcription. "Strong" promoters that efficiently interact with RNA polymerase induce high rates of transcription, leading to high levels of gene expression. Thus, from the temporal changes in the promoter sequences, we can estimate the variations in the gene expression levels during the geological time. Promoter sequences of Fe-SOD at each ancestral node of cyanobacteria were predicted from phylogenetic analysis, and the ancestral promoter sequences were compared to the promoters of known highly expressed genes. The similarity was low at the time of the emergence of cyanobacteria; however, increased at the branching nodes diverged 2.4 billon years ago. This roughly coincided with the onset of the GOE, implying that the transition from low to high gene

Integrating surface and mantle constraints for palaeo-ocean evolution: a tour of the Arctic and adjacent regions (Arne Richter Award for Outstanding Young Scientists Lecture)

Science.gov (United States)

Shephard, Grace E.

2016-04-01

Plate tectonic reconstructions heavily rely on absolute motions derived from hotspot trails or palaeomagnetic data and ocean-floor magnetic anomaies and fracture-zone geometries to constrain the detailed history of ocean basins. However, as oceanic lithosphere is progressively recycled into the mantle, kinematic data regarding the history of these now extinct-oceans is lost. In order to better understand their evolution, novel workflows, which integrate a wide range of complementary yet independent geological and geophysical datasets from both the surface and deep mantle, must be utilised. In particular, the emergence of time-dependent, semi or self-consistent geodynamic models of ever-increasing temporal and spatial resolution are revealing some critical constraints on the evolution and fate of oceanic slabs. The tectonic evolution of the circum-Arctic is no exception; since the breakup of Pangea, this enigmatic region has seen major plate reorganizations and the opening and closure of several ocean basins. At the surface, a myriad of potential kinematic scenarios including polarity, timing, geometry and location of subduction have emerged, including for systems along continental margins and intra-oceanic settings. Furthermore, recent work has reignited a debate about the origins of 'anchor' slabs, such as the Farallon and Mongol-Okhotsk slabs, which have been used to refine absolute plate motions. Moving to the mantle, seismic tomography models reveal a region peppered with inferred slabs, however assumptions about their affinities and subduction location, timing, geometry and polarity are often made in isolation. Here, by integrating regional plate reconstructions with insights from seismic tomography, satellite derived gravity gradients, slab sinking rates and geochemistry, I explore some Mesozoic examples from the palaeo-Arctic, northern Panthalassa and western margin of North America, including evidence for a discrete and previously undescribed slab under

Engineering Geology | Alaska Division of Geological & Geophysical Surveys

Science.gov (United States)

Alaska's Mineral Industry Reports AKGeology.info Rare Earth Elements WebGeochem Engineering Geology Alaska content Engineering Geology Additional information Engineering Geology Posters and Presentations Alaska Alaska MAPTEACH Tsunami Inundation Mapping Engineering Geology Staff Projects The Engineering Geology

Proceedings of the symposium on isotope geology progress: technology, methods, theory and application

International Nuclear Information System (INIS)

2003-11-01

The symposium was held in Beijing, Nov. 7-11, and the proceedings collects 122 articles, the contents include: new technology and new methods on isotopic test; isotope fractionation mechanism; the early evolution of the solar system and the Earth; continental dynamics and evolution of orogenic belts; minerals, energy and water; major history events on life origin, evolution and geology; changes in the Earth's global and modern environment--the oceans, the atmosphere, rivers and lakes, karst and soil, ecological agriculture and modern environment

Natural climate variations in a geological perspective

International Nuclear Information System (INIS)

Mikkelsen, N.; Kuijpers, A.

2001-01-01

The climate is constantly changing, and it has been changing throughout the geological history of the Earth. These natural changes have shown a variability with frequencies from millions of years to just a few hundreds or tens of years. Some of the variations have been rather dramatic - shifting from globally uniform and hot climates to regular ice ages - whereas other changes have been less spectacular. All natural climate variations have an impact on the physical and biological systems of the Earth - and on mankind and culture during the last hundred thousand years. In this chapter we shall discuss the natural climate changes that has taken place during the geological history of the Earth and comment on the impact of these changes on the cultural evolution of mankind with special emphasis on Greenland. (LN)

Muon Tomography for Geological Repositories.

Science.gov (United States)

Woodward, D.; Kudryavtsev, V.; Gluyas, J.; Clark, S. J.; Thompson, L. F.; Klinger, J.; Spooner, N. J.; Blackwell, T. B.; Pal, S.; Lincoln, D. L.; Paling, S. M.; Mitchell, C. N.; Benton, C.; Coleman, M. L.; Telfer, S.; Cole, A.; Nolan, S.; Chadwick, P.

2015-12-01

Cosmic-ray muons are subatomic particles produced in the upper atmosphere in collisions of primary cosmic rays with atoms in air. Due to their high penetrating power these muons can be used to image the content (primarily density) of matter they pass through. They have already been used to image the structure of pyramids, volcanoes and other objects. Their applications can be extended to investigating the structure of, and monitoring changes in geological formations and repositories, in particular deep subsurface sites with stored CO2. Current methods of monitoring subsurface CO2, such as repeat seismic surveys, are episodic and require highly skilled personnel to operate. Our simulations based on simplified models have previously shown that muon tomography could be used to continuously monitor CO2 injection and migration and complement existing technologies. Here we present a simulation of the monitoring of CO2 plume evolution in a geological reservoir using muon tomography. The stratigraphy in the vicinity of the reservoir is modelled using geological data, and a numerical fluid flow model is used to describe the time evolution of the CO2 plume. A planar detection region with a surface area of 1000 m2 is considered, at a vertical depth of 776 m below the seabed. We find that one year of constant CO2 injection leads to changes in the column density of about 1%, and that the CO2 plume is already resolvable with an exposure time of less than 50 days. The attached figure show a map of CO2 plume in angular coordinates as reconstructed from observed muons. In parallel with simulation efforts, a small prototype muon detector has been designed, built and tested in a deep subsurface laboratory. Initial calibrations of the detector have shown that it can reach the required angular resolution for muon detection. Stable operation in a small borehole within a few months has been demonstrated.

Natural analogues: studies of geological processes relevant to radioactive waste disposal in deep geological repositories

Energy Technology Data Exchange (ETDEWEB)

Russel, A.W. [Bedrock Geosciences, Auenstein (Switzerland); Reijonen, H.M. [Saanio and Rickkola Oy, Helsinki (Finland); McKinley, I.G. [MCM Consulting, Baden-Daettwil (Switzerland)

2015-06-15

The geological disposal of radioactive wastes is generally accepted to be the most practicable approach to handling the waste inventory built up from over 70 years accumulation of power production, research-medical-industrial and military wastes. Here, a brief overview of the approach to geological disposal is presented along with some information on repository design and the assessment of repository post-closure safety. One of the significant challenges for repository safety assessment is how to extrapolate the likely long-term (i.e. ten thousand to a million years) behaviour of the repository from the necessarily short term data from analytical laboratories and underground rock laboratories currently available. One approach, common to all fields of the geosciences, but also in such diverse fields as philosophy, biology, linguistics, law, etc., is to utilise the analogue argumentation methodology. For the specific case of radioactive waste management, the term 'natural analogue' has taken on a particular meaning associated with providing supporting arguments for a repository safety assessment. This approach is discussed here with a brief overview of how the study of natural (and, in particular, geological) systems can provide supporting information on the likely long-term evolution of a deep geological waste repository. The overall approach is discussed and some relevant examples are presented, including the use of uranium ore bodies to assess waste form stability, the investigation of native metals to define the longevity of waste containers and how natural clays can provide information on the stability of waste tunnel backfill material. (authors)

Natural analogues: studies of geological processes relevant to radioactive waste disposal in deep geological repositories

International Nuclear Information System (INIS)

Russel, A.W.; Reijonen, H.M.; McKinley, I.G.

2015-01-01

The geological disposal of radioactive wastes is generally accepted to be the most practicable approach to handling the waste inventory built up from over 70 years accumulation of power production, research-medical-industrial and military wastes. Here, a brief overview of the approach to geological disposal is presented along with some information on repository design and the assessment of repository post-closure safety. One of the significant challenges for repository safety assessment is how to extrapolate the likely long-term (i.e. ten thousand to a million years) behaviour of the repository from the necessarily short term data from analytical laboratories and underground rock laboratories currently available. One approach, common to all fields of the geosciences, but also in such diverse fields as philosophy, biology, linguistics, law, etc., is to utilise the analogue argumentation methodology. For the specific case of radioactive waste management, the term 'natural analogue' has taken on a particular meaning associated with providing supporting arguments for a repository safety assessment. This approach is discussed here with a brief overview of how the study of natural (and, in particular, geological) systems can provide supporting information on the likely long-term evolution of a deep geological waste repository. The overall approach is discussed and some relevant examples are presented, including the use of uranium ore bodies to assess waste form stability, the investigation of native metals to define the longevity of waste containers and how natural clays can provide information on the stability of waste tunnel backfill material. (authors)

2005 dossier: clay. Tome: safety evaluation of the geologic disposal

International Nuclear Information System (INIS)

2005-01-01

This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the safety aspects of an argilite-type geologic disposal facility for high-level and long-lived (HLLL) radioactive wastes. Content: 1 - safety approach: context and general goals, general safety principles, specificity of the argilite repository safety approach, general approach; 2 - general description: HLLL wastes, geologic context of the Meuse/Haute-Marne site, repository architecture; 3 - safety functions and disposal design: time and space scales, safety approach by functions, functional analysis methodology, analysis of safety functions during the construction, exploitation and observation phases, safety functions analysis during post-closure phase; 4 - operational safety: dosimetric evaluation, risk analysis (explosible gases, fire hazards, lift cage drop, container drop); 5 - long-term efficiency of the disposal facility: normal evolution scenario, from conceptual models to the safety calculation model, description of the safety model, quantitative evaluation of the normal evolution scenario, main lessons learnt from the efficiency analysis; 6 - management of uncertainties: identification, building up of altered situations, mastery of uncertainties; 7 - evaluation of altered evolution scenarios: sealing defect scenario, container defect scenario, drilling scenario, strongly degraded operation scenario; 8 - conclusions: lessons learnt, possible improvements. (J.S.)

Mesozoic to Eocene ductile deformation of western Central Iran: From Cimmerian collisional orogeny to Eocene exhumation

Science.gov (United States)

Kargaranbafghi, Fariba; Neubauer, Franz; Genser, Johann; Faghih, Ali; Kusky, Timothy

2012-09-01

To advance our understanding of the Mesozoic to Eocene tectonics and kinematics of basement units exposed in the south-western Central Iran plateau, this paper presents new structural and thermochronological data from the Chapedony metamorphic core complex and hangingwall units, particularly from the Posht-e-Badam complex. The overall Paleogene structural characteristics of the area are related to an oblique convergent zone. The Saghand area represents part of a deformation zone between the Arabian and Eurasian plates, and can be interpreted to result from the Central Iran intracontinental deformation acting as a weak zone during Mesozoic to Paleogene times. Field and microstructural evidence reveal that the metamorphic and igneous rocks suffered a ductile shear deformation including mylonitization at the hangingwall boundary of the Eocene Chapedony metamorphic core complex. Comparison of deformation features in the mylonites and other structural features within the footwall unit leads to the conclusion that the mylonites were formed in a subhorizontal shear zone by NE-SW stretching during Middle to Late Eocene extensional tectonics. The Chapedony metamorphic core complex is characterized by amphibolite-facies metamorphism and development of S and S-L tectonic fabrics. The Posht-e-Badam complex was deformed by two stages during Cimmerian tectonic processes forming the Paleo-Tethyan suture.

Anatexis, hybridization and the modification of ancient crust: Mesozoic plutonism in the Old Woman Mountains area, California

Science.gov (United States)

Miller, C.F.; Wooden, J.L.

1994-01-01

A compositionally expanded array of granitic (s.l.) magmas intruded the > 2 Ga crust of the Old Woman Mountains area between 160 and 70 Ma. These magmas were emplaced near the eastern (inland) edge of the Jurassic/Cretaceous arcs of western North America, in an area where magma flux, especially during the Jurassic, was considerably lower than to the west. The Jurassic intrusives and over half of the Cretaceous intrusives are predominantly metaluminous and variable in composition; a major Cretaceous suite comprises only peraluminous monzogranite. Only the Jurassic intrusions show clear evidence for the presence of mafic liquids. All units, including the most mafic rocks, reveal isotopic evidence for a significant crustal component. However, none of the Mesozoic intrusives matches in isotopic composition either average pre-intrusion crust or any major unit of the exposed crust. Elemental inconsistencies also preclude closed system derivation from exposed crust. Emplacement of these magmas, which doubled the volume of the mid- to upper crust, did not dramatically change its elemental composition. It did, however, affect its Nd and especially Sr isotopic composition and modify some of the distinctive aspects of the elemental chemistry. We propose that Jurassic magmatism was open-system, with a major influx of mantle-derived mafic magma interacting strongly with the ancient crust. Mesozoic crustal thickening may have led to closed-system crustal melting by the Late Cretaceous, but the deep crust had been profoundly modified by earlier Mesozoic hybridization so that crustal melts did not simply reflect the original crustal composition. The clear evidence for a crustal component in magmas of the Old Woman Mountains area may not indicate any fundamental differences from the processes at work elsewhere in this or other magmatic arcs where the role of pre-existing crust is less certain. Rather, a compositionally distinctive, very old crust may simply have yielded a more

Radioactive waste disposal in geological formations

International Nuclear Information System (INIS)

Gera, F.

1977-01-01

The nuclear energy controversy, now raging in several countries, is based on two main issues: the safety of nuclear plants and the possibility to dispose safely of the long-lived radioactive wastes. Consideration of the evolution of the hazard potential of waste in function of decay time leads to a somewhat conservative reference containment time in the order of one hundred thousand years. Several concepts have been proposed for the disposal of long-lived wastes. At the present time, emplacement into suitable geological formations under land areas can be considered the most promising disposal option. It is practically impossible to define detailed criteria to be followed in selecting suitable sites for disposal of long-lived wastes. Basically there is a single criterion, namely; that the geological environment must be able to contain the wastes for at least a hundred thousand years. However, due to the extreme variability of geological settings, it is conceivable that this basic capability could be provided by a great variety of different conditions. The predominant natural mechanism by which waste radionuclides could be moved from a sealed repository in a deep geological formation into the biosphere is leaching and transfer by ground water. Hence the greatest challenge is to give a satisfactory demonstration that isolation from ground water will persist over the required containment time. Since geological predictions are necessarily affected by fairly high levels of uncertainty, the only practical approach is not a straight-forward forecast of future geological events, but a careful assessment of the upper limits of geologic changes that could take place in the repository area over the next hundred thousand years. If waste containment were to survive these extreme geological changes the disposal site could be considered acceptable. If some release of activity were to take place in consequence of the hypothetical events the disposal solution might still be

New insights into Mesozoic cycad evolution: an exploration of anatomically preserved Cycadaceae seeds from the Jurassic Oxford Clay biota

Directory of Open Access Journals (Sweden)

Alan R.T. Spencer

2017-08-01

Full Text Available Most knowledge concerning Mesozoic Era floras has come from compression fossils. This has been augmented in the last 20 years by rarer permineralized material showing cellular preservation. Here, we describe a new genus of anatomically preserved gymnosperm seed from the Callovian–Oxfordian (Jurassic Oxford Clay Formation (UK, using a combination of traditional sectioning and synchrotron radiation X-ray micro-tomography (SRXMT. Oxfordiana motturii gen. et sp. nov. is large and bilaterally symmetrical. It has prominent external ribs, and has a three-layered integument comprising: a narrow outer layer of thick walled cells; a thick middle parenchymatous layer; and innermost a thin fleshy layer. The integument has a longitudinal interior groove and micropyle, enveloping a nucellus with a small pollen chamber. The large size, bilateral symmetry and integumentary groove demonstrate an affinity for the new species within the cycads. Moreover, the internal groove in extant taxa is an autapomorphy of the genus Cycas, where it facilitates seed germination. Based upon the unique seed germination mechanism shared with living species of the Cycadaceae, we conclude that O. motturii is a member of the stem-group lineage leading to Cycas after the Jurassic divergence of the Cycadaceae from other extant cycads. SRXMT—for the first time successfully applied to fossils already prepared as slides—reveals the distribution of different mineral phases within the fossil, and allows us to evaluate the taphonomy of Oxfordiana. An early pyrite phase replicates the external surfaces of individual cells, a later carbonate component infilling void spaces. The resulting taphonomic model suggests that the relatively small size of the fossils was key to their exceptional preservation, concentrating sulfate-reducing bacteria in a locally closed microenvironment and thus facilitating soft-tissue permineralization.

Geology and Geochemistry of some crystalline basement rocks in ilesha area, southwestern nigeria: implications on provenance and evolution

International Nuclear Information System (INIS)

Oyinloye, A.O.

2007-01-01

Geological and geochemical study of the basement complex rocks in ilesha schist belt revealed that amphibolite, hornblende gneiss and granite gneiss are the major constituents. The gneisses are composed of similar rock forming silicates with variations in abundance. The amphibolite being a mafic rock has different compositions, containing abundant pyroxene, actinolite and tremolite. Monazite is present in the mineralogy of all these rocks. Chemical composition of these rocks revealed that they are petrogenetically related. Geochemical diagrams, plotted from chemical composition of these rocks, REE fractionation trends and presence of monazite in their mineralogy reveal that all these rocks were derived from a mixed magma source which did not originate from a pure tipper mantle, but possibly from a back arc tectonic setting. The pattern of the REE, progressively increasing negative Eu/Eu anomaly, La/sub N//Yb/sub N/ from the amphibolite to the granite gneiss and marked Eu depletion tend to implicate evolution through fractionation of a mixed basaltic magma to form the precursor of these rocks. The amphibolite probably represents the sample of the original basaltic magma. (author)

Mayer Kangri metamorphic complexes in Central Qiangtang (Tibet, western China): implications for the Triassic-early Jurassic tectonics associated with the Paleo-Tethys Ocean

Science.gov (United States)

Wang, Yixuan; Liang, Xiao; Wang, Genhou; Yuan, Guoli; Bons, Paul D.

2018-03-01

The Mesozoic orogeny in Central Qiangtang Metamorphic Belt, northern Tibet, provides important insights into the geological evolution of the Paleo-Tethys Ocean. However, the Triassic-early Jurassic tectonics, particularly those associated with the continental collisionstage, remains poorly constrained. Here we present results from geological mapping, structural analysis, P-T data, and Ar-Ar geochronology of the Mayer Kangri metamorphic complex. Our data reveal an E-W-trending, 2 km wide dome-like structure associated with four successive tectonic events during the Middle Triassic and Early Jurassic. Field observations indicate that amphibolite and phengite schist complexes in this complex are separated from the overlying lower greenschist mélange by normal faulting with an evident dextral shearing component. Open antiform-like S2 foliation of the footwall phengite schist truncates the approximately north-dipping structures of the overlying mélange. Microtextures and mineral chemistry of amphibole reveal three stages of growth: Geothermobarometric estimates yield temperatures and pressures of 524 °C and 0.88 GPa for pargasite cores, 386 °C and 0.34 GPa for actinolite mantles, and 404 °C and 0.76 GPa for winchite rims. Peak blueschist metamorphism in the phengite schist occurred at 0.7-1.1 GPa and 400 °C. Our Ar-Ar dating of amphibole reveals rim-ward decreasing in age bands, including 242.4-241.2 Ma, ≥202.6-196.8, and 192.9-189.8 Ma. The results provide evidence for four distinct phases of Mesozoic tectonic evolution in Central Qiangtang: (1) northward oceanic subduction beneath North Qiangtang ( 244-220 Ma); (2) syn-collisional slab-break off (223-202 Ma); (3) early collisional extension driven by buoyant extrusion flow from depth ( 202.6-197 Ma); and (4) post-collision contraction and reburial (195.6-188.7 Ma).

Geology of Mars after the first 40 years of exploration

International Nuclear Information System (INIS)

Rossi, Angelo Pio; Van Gasselt, Stephan

2010-01-01

The knowledge of Martian geology has increased enormously in the last 40 yr. Several missions orbiting or roving Mars have revolutionized our understanding of its evolution and geological features, which in several ways are similar to Earth, but are extremely different in many respects. The impressive dichotomy between the two Martian hemispheres is most likely linked to its impact cratering history, rather than internal dynamics such as on Earth. Mars' volcanism has been extensive, very long-lived and rather constant in its setting. Water was available in large quantities in the distant past of Mars, when a magnetic field and more vigorous tectonics were active. Exogenic forces have been shaping Martian landscapes and have led to a plethora of landscapes shaped by wind, water and ice. Mars' dynamical behavior continues, with its climatic variation affecting climate and geology until very recent times. This paper tries to summarize major highlights in Mars' Geology, and points to deeper and more extensive sources of important scientific contributions and future exploration. (invited reviews)

Rates of morphological evolution are heterogeneous in Early Cretaceous birds

Science.gov (United States)

Lloyd, Graeme T.

2016-01-01

The Early Cretaceous is a critical interval in the early history of birds. Exceptional fossils indicate that important evolutionary novelties such as a pygostyle and a keeled sternum had already arisen in Early Cretaceous taxa, bridging much of the morphological gap between Archaeopteryx and crown birds. However, detailed features of basal bird evolution remain obscure because of both the small sample of fossil taxa previously considered and a lack of quantitative studies assessing rates of morphological evolution. Here we apply a recently available phylogenetic method and associated sensitivity tests to a large data matrix of morphological characters to quantify rates of morphological evolution in Early Cretaceous birds. Our results reveal that although rates were highly heterogeneous between different Early Cretaceous avian lineages, consistent patterns of significantly high or low rates were harder to pinpoint. Nevertheless, evidence for accelerated evolutionary rates is strongest at the point when Ornithuromorpha (the clade comprises all extant birds and descendants from their most recent common ancestors) split from Enantiornithes (a diverse clade that went extinct at the end-Cretaceous), consistent with the hypothesis that this key split opened up new niches and ultimately led to greater diversity for these two dominant clades of Mesozoic birds. PMID:27053742

Geodiversity: Exploration of 3D geological model space

Science.gov (United States)

Lindsay, M. D.; Jessell, M. W.; Ailleres, L.; Perrouty, S.; de Kemp, E.; Betts, P. G.

2013-05-01

The process of building a 3D model necessitates the reconciliation of field observations, geophysical interpretation, geological data uncertainty and the prevailing tectonic evolution hypotheses and interpretations. Uncertainty is compounded when clustered data points collected at local scales are statistically upscaled to one or two points for use in regional models. Interpretation is required to interpolate between sparse field data points using ambiguous geophysical data in covered terranes. It becomes clear that multiple interpretations are possible during model construction. The various interpretations are considered as potential natural representatives, but pragmatism typically dictates that just a single interpretation is offered by the modelling process. Uncertainties are introduced into the 3D model during construction from a variety of sources and through data set optimisation that produces a single model. Practices such as these are likely to result in a model that does not adequately represent the target geology. A set of geometrical ‘geodiversity’ metrics are used to analyse a 3D model of the Gippsland Basin, southeastern Australia after perturbing geological input data via uncertainty simulation. The resulting sets of perturbed geological observations are used to calculate a suite of geological 3D models that display a range of geological architectures. The concept of biodiversity has been adapted for the geosciences to quantify geometric variability, or geodiversity, between models in order to understand the effect uncertainty has models geometry. Various geometrical relationships (depth, volume, contact surface area, curvature and geological complexity) are used to describe the range of possibilities exhibited throughout the model suite. End-member models geodiversity metrics are classified in a similar manner to taxonomic descriptions. Further analysis of the model suite is performed using principal component analysis (PCA) to determine

Geological evolution, palaeoclimate and historical development of the Forsmark and Laxemar-Simpevarp areas. Site descriptive modelling SDM-Site

Energy Technology Data Exchange (ETDEWEB)

Soederbaeck, Bjoern [ed.

2008-06-15

The Swedish Nuclear Fuel and Waste Management Company (SKB) is undertaking site characterization at two different locations, the Forsmark and Laxemar-Simpevarp areas, with the objective of siting a geological repository for spent nuclear fuel. The site investigations started in 2002 and were completed in 2007. The analysis and modelling of data from the site investigations, which have taken place during and after these investigations, provide a foundation for the development of an integrated, multidisciplinary site descriptive model (SDM) for each of the two sites. A site descriptive model constitutes a description of the site and its regional setting, covering the current state of the geosphere and the biosphere, as well as those natural processes that affect or have affected their long-term development. Hitherto, a number of reports presenting preliminary site descriptive models for Forsmark and Laxemar-Simpevarp have been published. In these reports, the evolutionary and historical aspects of the site were included in a separate chapter. The present report comprises a further elaboration of the evolutionary and historical information included in the preliminary SDM reports, but presented here in a separate, supplementary report to the final site description, SDM-Site. The report is common to the two investigated areas, and the overall objective is to describe the long-term geological evolution, the palaeoclimate, and the post-glacial development of ecosystems and of the human population at the two sites. The report largely consists of a synthesis of information derived from the scientific literature and other sources not related to the site investigations. However, considerable information from the site investigations that has contributed to our understanding of the past development at each site is also included. This unique synthesis of both published information in a regional perspective and new site-specific information breaks new ground in our understanding

Geological evolution, palaeoclimate and historical development of the Forsmark and Laxemar-Simpevarp areas. Site descriptive modelling SDM-Site

International Nuclear Information System (INIS)

Soederbaeck, Bjoern

2008-06-01

The Swedish Nuclear Fuel and Waste Management Company (SKB) is undertaking site characterization at two different locations, the Forsmark and Laxemar-Simpevarp areas, with the objective of siting a geological repository for spent nuclear fuel. The site investigations started in 2002 and were completed in 2007. The analysis and modelling of data from the site investigations, which have taken place during and after these investigations, provide a foundation for the development of an integrated, multidisciplinary site descriptive model (SDM) for each of the two sites. A site descriptive model constitutes a description of the site and its regional setting, covering the current state of the geosphere and the biosphere, as well as those natural processes that affect or have affected their long-term development. Hitherto, a number of reports presenting preliminary site descriptive models for Forsmark and Laxemar-Simpevarp have been published. In these reports, the evolutionary and historical aspects of the site were included in a separate chapter. The present report comprises a further elaboration of the evolutionary and historical information included in the preliminary SDM reports, but presented here in a separate, supplementary report to the final site description, SDM-Site. The report is common to the two investigated areas, and the overall objective is to describe the long-term geological evolution, the palaeoclimate, and the post-glacial development of ecosystems and of the human population at the two sites. The report largely consists of a synthesis of information derived from the scientific literature and other sources not related to the site investigations. However, considerable information from the site investigations that has contributed to our understanding of the past development at each site is also included. This unique synthesis of both published information in a regional perspective and new site-specific information breaks new ground in our understanding

Scientific basis to assess the potential for geological sequestration of CO{sub 2} in Switzerland

Energy Technology Data Exchange (ETDEWEB)

Diamond, L. W.; Chevalier, G. [Institut fuer Geologie, Universitaet Bern, Bern (Switzerland); Leu, W. [Geoform AG, Geologische Beratungen und Studien, Villeneuve (former Minusio) (Switzerland)

2010-07-01

Possibilities to sequester anthropogenic CO{sub 2} in deep geological formations are being investigated worldwide, but the potential within Switzerland has not yet been evaluated. This study presents a first-order appraisal based solely on geological criteria collated from the literature. The Swiss Molasse Basin (SMB) and the adjacent Folded Jura are the only realms of the country where CO{sub 2} could conceivably be stored in saline aquifers. Evaluation of geological criteria at the basin-wide scale shows that the SMB-Jura has moderate potential (score of 0.6 on a scale from 0 to 1) when compared to basins elsewhere. At the intrabasinal scale, inspection of the stratigraphy reveals four regional candidate aquifers that are sealed by suitable caprocks: top Basement plus basal Mesozoic sandstones, all sealed by the Anhydrite Group; Upper Muschelkalk sealed by the Gipskeuper; Hauptrogenstein sealed by the Effinger Member, and Upper Malm plus Lower Cretaceous sealed by the Lower Freshwater Molasse. Nine geological criteria are defined to evaluate the storage potential of these and other smaller-scale candidates. A numerical scoring and weighting scheme allows the criteria to be assessed simultaneously, permitting the storage potential to be depicted using the 0-1 scale in contoured maps. Approximately 5000 km{sup 2} of the central SMB exhibits potentials between 0.6 and 0.96. The Fribourg-Olten-Lucerne area is the most favoured owing to the presence of several sealed aquifers within the preferred 800-2500 m depth interval, and to its low seismicity, low geothermal gradient, low fault density, and long groundwater residence times. Smaller areas with good potential lie between Zurich and St. Gall. In contrast, western Switzerland, the Jura and the southern SMB have markedly poorer potential. Considering only the portions of the aquifers with potential above 0.6, the theoretical, effective storage capacity of the basin is estimated to be 2680 million tonnes of CO{sub 2

The May 20 (MW 6.1) and 29 (MW 6.0), 2012, Emilia (Po Plain, northern Italy) earthquakes: New seismotectonic implications from subsurface geology and high-quality hypocenter location

Science.gov (United States)

Carannante, Simona; Argnani, Andrea; Massa, Marco; D'Alema, Ezio; Lovati, Sara; Moretti, Milena; Cattaneo, Marco; Augliera, Paolo

2015-08-01

This study presents new geological and seismological data that are used to assess the seismic hazard of a sector of the Po Plain (northern Italy), a large alluvial basin hit by two strong earthquakes on May 20 (MW 6.1) and May 29 (MW 6.0), 2012. The proposed interpretation is based on high-quality relocation of 5369 earthquakes ('Emilia sequence') and a dense grid of seismic profiles and exploration wells. The analyzed seismicity was recorded by 44 seismic stations, and initially used to calibrate new one-dimensional and three-dimensional local Vp and Vs velocity models for the area. Considering these new models, the initial sparse hypocenters were then relocated in absolute mode and adjusted using the double-difference relative location algorithm. These data define a seismicity that is elongated in the W-NW to E-SE directions. The aftershocks of the May 20 mainshock appear to be distributed on a rupture surface that dips ~ 45° SSW, and the surface projection indicates an area ~ 10 km wide and 23 km long. The aftershocks of the May 29 mainshock followed a steep rupture surface that is well constrained within the investigated volume, whereby the surface projection of the blind source indicates an area ~ 6 km wide and 33 km long. Multichannel seismic profiles highlight the presence of relevant lateral variations in the structural style of the Ferrara folds that developed during the Pliocene and Pleistocene. There is also evidence of a Mesozoic extensional fault system in the Ferrara arc, with faults that in places have been seismically reactivated. These geological and seismological observations suggest that the 2012 Emilia earthquakes were related to ruptures along blind fault surfaces that are not part of the Pliocene-Pleistocene structural system, but are instead related to a deeper system that is itself closely related to re-activation of a Mesozoic extensional fault system.

Initial magmatism and evolution of the Izu-Bonin-Mariana Arc

Science.gov (United States)

Arculus, R. J.

2016-12-01

Expedition 351 of the IODP targeted site U1438 in the Amami Sankaku Basin, northwestern Philippine Sea , 70 km west of the northern Kyushu-Palau Ridge (KPR). The latter formed a chain of stratovolcanoes of the Izu-Bonin-Mariana (IBM) arc, and a remnant arc following migration of the volcanic front eastwards during Shikoku backarc basin formation in the Miocene. Unravelling causes of subduction initiation drove the primary aims of the Expedition involving recovery of igneous basement below the KPR, and a history of the magmatic evolution of the KPR preserved in a clastic record. All these aims were achieved, but with some surprises. Out of 1600m drilled in 4700m water depth, 150m of igneous oceanic crust comprising low-K, tholeiitic basalt lava flows were recovered at U1438. The lavas are variably glassy to microphyric, Cr-spinel-olivine-plagioclase-clinopyroxene-bearing, have high V/Ti, very low absolute rare earth element abundances and low La/Yb, and radiogenic Hf at a given 143/144Nd compared to basalts of mid-ocean ridges. The basement is geochemically and petrologically similar to so-called "forearc basalts" recovered trenchward of the active IBM volcanic front, and of similar or older age (≥52Ma). Highly melt-depleted mantle source(s) were involved and high-temperature, low-pressure dehydration of the subducting Pacific Plate. Compositions of glass (formerly melt) inclusions in clinopyroxene-bearing clasts and sandstones in sediments overlying the basement show a change from medium-Fe (aka "calcalkaline") to low-Fe (tholeiitic) magmas during the Eocene-Oligocene evolution of the KPR. Widespread magmatism along- and across-strike of the nascent IBM system coupled with geologic constraints from the western Philippine Sea, indicate subduction initiation at the IBM arc likely propagated adjacent to Mesozoic-aged arcs/basins to the west of the KPR, following plate reorganization subsequent to the demise of the Izanagi-Pacific Ridge along eastern Asia at 60Ma

Viruses as new agents of organomineralization in the geological record.

Science.gov (United States)

Pacton, Muriel; Wacey, David; Corinaldesi, Cinzia; Tangherlini, Michael; Kilburn, Matt R; Gorin, Georges E; Danovaro, Roberto; Vasconcelos, Crisogono

2014-07-03

Viruses are the most abundant biological entities throughout marine and terrestrial ecosystems, but little is known about virus-mineral interactions or the potential for virus preservation in the geological record. Here we use contextual metagenomic data and microscopic analyses to show that viruses occur in high diversity within a modern lacustrine microbial mat, and vastly outnumber prokaryotes and other components of the microbial mat. Experimental data reveal that mineral precipitation takes place directly on free viruses and, as a result of viral infections, on cell debris resulting from cell lysis. Viruses are initially permineralized by amorphous magnesium silicates, which then alter to magnesium carbonate nanospheres of ~80-200 nm in diameter during diagenesis. Our findings open up the possibility to investigate the evolution and geological history of viruses and their role in organomineralization, as well as providing an alternative explanation for enigmatic carbonate nanospheres previously observed in the geological record.

Geology for a changing world 2010-2020-Implementing the U.S. Geological Survey science strategy

Science.gov (United States)

Gundersen, Linda C.S.; Belnap, Jayne; Goldhaber, Martin; Goldstein, Arthur; Haeussler, Peter J.; Ingebritsen, S.E.; Jones, John W.; Plumlee, Geoffrey S.; Thieler, E. Robert; Thompson, Robert S.; Back, Judith M.

2011-01-01

This report describes a science strategy for the geologic activities of the U.S. Geological Survey (USGS) for the years 2010-2020. It presents six goals with accompanying strategic actions and products that implement the science directions of USGS Circular 1309, 'Facing Tomorrow's Challenges-U.S. Geological Survey Science in the Decade 2007-2017.' These six goals focus on providing the geologic underpinning needed to wisely use our natural resources, understand and mitigate hazards and environmental change, and understand the relationship between humans and the environment. The goals emphasize the critical role of the USGS in providing long-term research, monitoring, and assessments for the Nation and the world. Further, they describe measures that must be undertaken to ensure geologic expertise and knowledge for the future. The natural science issues facing today's world are complex and cut across many scientific disciplines. The Earth is a system in which atmosphere, oceans, land, and life are all connected. Rocks and soils contain the answers to important questions about the origin of energy and mineral resources, the evolution of life, climate change, natural hazards, ecosystem structures and functions, and the movements of nutrients and toxicants. The science of geology has the power to help us understand the processes that link the physical and biological world so that we can model and forecast changes in the system. Ensuring the success of this strategy will require integration of geological knowledge with the other natural sciences and extensive collaboration across USGS science centers and with partners in Federal, State, and local agencies, academia, industry, nongovernmental organizations and, most importantly, the American public. The first four goals of this report describe the scientific issues facing society in the next 10 years and the actions and products needed to respond to these issues. The final two goals focus on the expertise and

A BRIEF NOTE ON MINERAL EVOLUTION AND BIOCHEMISTRY

Directory of Open Access Journals (Sweden)

José María Amigó

2014-12-01

Full Text Available The natural inorganic materials (minerals and rocks exceed the limits of the Earth.Therefore, the geology, which is the study of the Earth, represents only a small part of thenatural inorganic world. Certain questions about the genesis of the universe are related tothe evolution of our solar system and the evolution of life on our planet. In this paper, recentcontributions from experimental physical natural-sciences to the formation of the universe(about 15 billion BP coupled with the occurrence of minerals (4 million years BP and thebiochemical appearance of life (not more than 3 million years on the Earth are discussed.When Earth was formed, none of the more than 4,400 minerals we know today were existed.Cosmologists estimate that nearly ten billion years after the Big Bang the first elementsproduced by the melting process. The geological history of mineral evolution on the Earthis an interesting tool to study terrestrial and/or extraterrestrial mineralogy in regard toastronomy, biology, chemistry and other experimental natural sciences

Zircon Hf-O isotopic constraints on the origin of Late Mesozoic felsic volcanic rocks from the Great Xing'an Range, NE China

Science.gov (United States)

Gong, Mingyue; Tian, Wei; Fu, Bin; Wang, Shuangyue; Dong, Jinlong

2018-05-01

The voluminous Late Mesozoic magmatism was related to extensive re-melting of juvenile materials that were added to the Central East Asia continent in Phanerozoic time. The most favoured magma generation mechanism of Late Mesozoic magmas is partial melting of underplated lower crust that had radiogenic Hf-Nd isotopic characteristics, but this mechanism faces difficulties when interpreting other isotopic data. The tectonic environment controlling the generation of the Late Mesozoic felsic magmas is also in dispute. In this study, we obtained new U-Pb ages, and geochemical and isotopic data of representative Jurassic (154.4 ± 1.5 Ma) and Cretaceous (140.2 ± 1.5 Ma) felsic volcanic samples. The Jurassic sample has inherited zircon cores of Permian age, with depleted mantle-like εHf(t) of +7.4 - +8.5, which is in contrast with those of the magmatic zircons (εHf(t) = +2.4 ± 0.7). Whereas the inherited cores and the magmatic zircons have identical mantle-like δ18O composition ranges (4.25-5.29‰ and 4.69-5.54‰, respectively). These Hf-O isotopic characteristics suggest a mixed source of enriched mantle materials rather than ancient crustal components and a depleted mantle source represented by the inherited Permian zircon core. This mechanism is manifested by the eruption of Jurassic alkaline basalts originated from an enriched mantle source. The Cretaceous sample has high εHf(t) of +7.0 - +10.5, suggesting re-melting of a mafic magma derived from a depleted mantle-source. However, the sub-mantle zircon δ18O values (3.70-4.58‰) suggest the depleted mantle-derived mafic source rocks had experienced high temperature hydrothermal alteration at upper crustal level. Therefore, the Cretaceous felsic magma, if not all, could be generated by re-melting of down-dropped supracrustal volcanic rocks that experienced high temperature oxygen isotope alteration. The two processes, enriched mantle-contribution and supracrustal juvenile material re-melting, are new

Considering timescales in the post-closure safety of geological disposal of radioactive waste

International Nuclear Information System (INIS)

2009-01-01

A key challenge in the development of safety cases for the deep geological disposal of radioactive waste is handling the long time frame over which the radioactive waste remains hazardous. The intrinsic hazard of the waste decreases with time, but some hazard remains for extremely long periods. Safety cases for geological disposal typically address performance and protection for thousands to millions of years into the future. Over such periods, a wide range of events and processes operating over many different timescales may impact on a repository and its environment. Uncertainties in the predictability of such factors increase with time, making it increasingly difficult to provide definite assurances of a repository's performance and the protection it may provide over longer timescales. Timescales, the level of protection and the assurance of safety are all linked. Approaches to handling timescales for the geological disposal of radioactive waste are influenced by ethical principles, the evolution of the hazard over time, uncertainties in the evolution of the disposal system (and how these uncertainties themselves evolve) and the stability and predictability of the geological environment. Conversely, the approach to handling timescales can affect aspects of repository planning and implementation including regulatory requirements, siting decisions, repository design, the development and presentation of safety cases and the planning of pre- and post-closure institutional controls such as monitoring requirements. This is an area still under discussion among NEA member countries. This report reviews the current status and ongoing discussions of this issue. (author)

Latitudinal diversity gradients in Mesozoic non-marine turtles

Science.gov (United States)

Nicholson, David B.; Holroyd, Patricia A.; Valdes, Paul; Barrett, Paul M.

2016-11-01

The latitudinal biodiversity gradient (LBG)-the pattern of increasing taxonomic richness with decreasing latitude-is prevalent in the structure of the modern biota. However, some freshwater taxa show peak richness at mid-latitudes; for example, extant Testudines (turtles, terrapins and tortoises) exhibit their greatest diversity at 25° N, a pattern sometimes attributed to recent bursts of climatically mediated species diversification. Here, we test whether this pattern also characterizes the Mesozoic distribution of turtles, to determine whether it was established during either their initial diversification or as a more modern phenomenon. Using global occurrence data for non-marine testudinate genera, we find that subsampled richness peaks at palaeolatitudes of 15-30° N in the Jurassic, 30-45° N through the Cretaceous to the Campanian, and from 30° to 60° N in the Maastrichtian. The absence of a significant diversity peak in southern latitudes is consistent with results from climatic models and turtle niche modelling that demonstrate a dearth of suitable turtle habitat in Gondwana during the Jurassic and Late Cretaceous. Our analyses confirm that the modern testudinate LBG has a deep-time origin and further demonstrate that LBGs are not always expressed as a smooth, equator-to-pole distribution.

Synthesis on the spent fuel long term evolution

Energy Technology Data Exchange (ETDEWEB)

Ferry, C.; Poinssot, Ch.; Lovera, P.; Poulesquen, A. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC), 91 - Gif sur Yvette (France); Broudic, V. [CEA Cadarache, Direction des Reacteurs Nucleaires (DRN), 13 - Saint Paul lez Durance (France); Cappelaere, Ch. [CEA Saclay, Dept. des Materiaux pour le Nucleaire(DMN), 91 - Gif-sur-Yvette (France); Desgranges, L. [CEA Cadarache, Direction des Reacteurs Nucleaires (DRN), 13 - Saint-Paul-lez-Durance (France); Garcia, Ph. [CEA Cadarache, Dept. d' Etudes des Combustibles (DEC), 13 - Saint Paul lez Durance (France); Jegou, Ch.; Roudil, D. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN), 30 - Marcoule (France); Lovera, P.; Poulesquen, A. [CEA Saclay, Dept. de Physico-Chimie (DPC), 91 - Gif sur Yvette (France); Marimbeau, P. [CEA Cadarache, Dir. de l' Energie Nucleaire (DEN), 13 - Saint-Paul-lez-Durance (France); Gras, J.M.; Bouffioux, P. [Electricite de France (EDF), 75 - Paris (France)

2005-07-01

The French research on spent fuel long term evolution has been performed by CEA (Commissariat a l'Energie Atomique) since 1999 in the PRECCI project with the support of EDF (Electricite de France). These studies focused on the spent fuel behaviour under various conditions encountered in dry storage or in deep geological disposal. Three main types of conditions were discerned: - The evolution in a closed system which corresponds to the normal scenario in storage and to the first confinement phase in disposal; - The evolution in air which corresponds to an incidental loss of confinement during storage or to a rupture of the canister before the site re-saturation in geological disposal; - The evolution in water which corresponds to the normal scenario after the breaching of the canister in repository conditions. This document produced in the frame of the PRECCI project is an overview of the state of knowledge in 2004 concerning the long-term behavior of spent fuel under these various conditions. The state of the art was derived from the results obtained under the PRECCI project as well as from a review of the literature and of data acquired under the European project on Spent Fuel Stability under Repository Conditions. The main results issued from the French research are underlined. (authors)

Synthesis on the spent fuel long term evolution

International Nuclear Information System (INIS)

Ferry, C.; Poinssot, Ch.; Lovera, P.; Poulesquen, A.; Broudic, V.; Cappelaere, Ch.; Desgranges, L.; Garcia, Ph.; Jegou, Ch.; Roudil, D.; Lovera, P.; Poulesquen, A.; Marimbeau, P.; Gras, J.M.; Bouffioux, P.

2005-01-01

The French research on spent fuel long term evolution has been performed by CEA (Commissariat a l'Energie Atomique) since 1999 in the PRECCI project with the support of EDF (Electricite de France). These studies focused on the spent fuel behaviour under various conditions encountered in dry storage or in deep geological disposal. Three main types of conditions were discerned: - The evolution in a closed system which corresponds to the normal scenario in storage and to the first confinement phase in disposal; - The evolution in air which corresponds to an incidental loss of confinement during storage or to a rupture of the canister before the site re-saturation in geological disposal; - The evolution in water which corresponds to the normal scenario after the breaching of the canister in repository conditions. This document produced in the frame of the PRECCI project is an overview of the state of knowledge in 2004 concerning the long-term behavior of spent fuel under these various conditions. The state of the art was derived from the results obtained under the PRECCI project as well as from a review of the literature and of data acquired under the European project on Spent Fuel Stability under Repository Conditions. The main results issued from the French research are underlined. (authors)

Biosilicification Drives a Decline of Dissolved Si in the Oceans through Geologic Time

Directory of Open Access Journals (Sweden)

Daniel J. Conley

2017-12-01

Full Text Available Biosilicification has driven variation in the global Si cycle over geologic time. The evolution of different eukaryotic lineages that convert dissolved Si (DSi into mineralized structures (higher plants, siliceous sponges, radiolarians, and diatoms has driven a secular decrease in DSi in the global ocean leading to the low DSi concentrations seen today. Recent studies, however, have questioned the timing previously proposed for the DSi decreases and the concentration changes through deep time, which would have major implications for the cycling of carbon and other key nutrients in the ocean. Here, we combine relevant genomic data with geological data and present new hypotheses regarding the impact of the evolution of biosilicifying organisms on the DSi inventory of the oceans throughout deep time. Although there is no fossil evidence for true silica biomineralization until the late Precambrian, the timing of the evolution of silica transporter genes suggests that bacterial silicon-related metabolism has been present in the oceans since the Archean with eukaryotic silicon metabolism already occurring in the Neoproterozoic. We hypothesize that biological processes have influenced oceanic DSi concentrations since the beginning of oxygenic photosynthesis.

Coal Age Galapogos: Joggins and the lions of nineteenth century geology

Energy Technology Data Exchange (ETDEWEB)

Calder, J.H. [Nova Scotia Department of Natural Resources, Halifax, NS (Canada)

2006-07-01

Since the 1870s, the Joggins coastal section has been recognized as an outstanding section of Carboniferous strata. Accounts about the geology of the Joggins area first appeared in the published literature in 1828. Early history, visits by Sir Charles Lyell and Sir William Logan in 1842 and later, early Geological Survey of Canada field projects, tree trunk fauna, O.C. Marsh's fossil discoveries, Lyell, Dawson and Darwin on evolution, the origin of coal, and discoveries by Sir William Dawson are discussed. The Joggins coastal section has been placed on Canada's Tentative List of future World Heritage Site nominees. 71 refs., 18 figs.

(ajst) structural evolution of bode saadu area

African Journals Online (AJOL)

opiyo

2, pp. 17-24. STRUCTURAL EVOLUTION OF BODE SAADU AREA,. SOUTHWESTERN NIGERIA. C. T. Okonkwo. Department of Geology, University of Ilorin P.M.B. 1515, Ilorin, Nigeria. E-mail cokonkwo@unilorin.edu.ng. ABSTRACT: The Bode Saadu area comprises metasedimentary and metaigneous rocks which have.

Structural Characteristics of Paleozoic and Geological Significance of Oil and Gas of Dongpu Depression

Institute of Scientific and Technical Information of China (English)

杨世刚

2003-01-01

The Dongpu depression has experienced a complicated evolution of structure since Mesozoic. The Paleozoic carbonate rock has been strongly reformed and the buried hills with different characteristics of structure are developed in the depression. There exist lots of groups of fault structures with strikes of NNE(or NE),NW, near NS and EW etc., of which the faults with strikes of NNE and NW play an important controlling role on present-day structural framework of the depression. The faults with near NS-striking and EW-striking deeply affect the establishment of structural framework of basement of the depression. Although most of the fractures are filled by calcite and other minerals, under the action of later structural stress, the earlier fractures could change their features into tensional ones. Therefore, much attention should be paid to the exploration and exploitation of Paleozoic oil and gas in Dongpu depression.

Study on the remote sensing geological information of uranium mineralization in Western Liaoning and Northern Hebei

International Nuclear Information System (INIS)

Yu Baoshan; Wang Dianbai; Jin Shihua; Qiao Rui

1996-01-01

Based on the whole areal geological map joint application rd exploitation, composite forming map, generalization analysis and field examination in detail of key region that mainly depend on remote sensing information and generalize the data of geology, geophysical and geochemical prospecting, and geohydrology, this paper reveals the structure framework, regional geological background, uranium metallogenic condition and space time distribution rule of orustal evolution and its result, and set up the interpretation marks of arc-shaped structure in different of rock area and discusses its geological genesis. The author also interprets volcanic apparatus, small type closed sedimentary basin, magmatic rock body which relate closely to uranium deposit, ore control structure and occurrence and type of mineralization alteration envelope. The thermal halo point of satellite image is emphatically interpreted and its geological meaning and its relation to uranium deposit is discussed. Remote sensing geological prospecting ore model and synthetic provision model is determined lastly

Deep storage of radioactive waste from a geological point of view

International Nuclear Information System (INIS)

Venzlaff, Helmut

2015-01-01

For a deep storage of radioactive waste geologists gave their preference to salt prior to other rock complexes such as clay or granite. Major deposits from pure rock salt are particularly suitable to safely seal radioactive wastes from the biosphere because due to their plasticity they are free from fissures in which liquids and gases could circulate and because their thermal conductivity is higher than of other rocks. The geological stability of salt domes can be shown by their geological evolution. Thus the salt dome in Gorleben was formed 100 million years ago and is older than the Atlantic, the Alps or the ascent of the low mountain range. During this long period it survived ocean floods, mountain formations, earthquakes, volcanism and ice ages without considerably changing its shape. There are no geological reasons, why it should not remain stable during the next million years.

Deep storage of radioactive waste from a geological point of view

Energy Technology Data Exchange (ETDEWEB)

Venzlaff, Helmut [Federal Institute for Geo-Sciences and Raw Materials, Hannover (Germany)

2015-08-15

For a deep storage of radioactive waste geologists gave their preference to salt prior to other rock complexes such as clay or granite. Major deposits from pure rock salt are particularly suitable to safely seal radioactive wastes from the biosphere because due to their plasticity they are free from fissures in which liquids and gases could circulate and because their thermal conductivity is higher than of other rocks. The geological stability of salt domes can be shown by their geological evolution. Thus the salt dome in Gorleben was formed 100 million years ago and is older than the Atlantic, the Alps or the ascent of the low mountain range. During this long period it survived ocean floods, mountain formations, earthquakes, volcanism and ice ages without considerably changing its shape. There are no geological reasons, why it should not remain stable during the next million years.

California Geological Survey Geologic Map Index

Data.gov (United States)

California Natural Resource Agency — All the individual maps from the Geologic Atlas of California and the Regional Geologic map series have been georeferenced for display in a GIS (and viewable online...

Developing, choosing and using landscape evolution models to inform field-based landscape reconstruction studies : Developing, choosing and using landscape evolution models

NARCIS (Netherlands)

Temme, A.j.a.m.; Armitage, J.; Attal, M.; Van Gorp, W.; Coulthard, T.j.; Schoorl, J.m.

2017-01-01

Landscape evolution models (LEMs) are an increasingly popular resource for geomorphologists as they can operate as virtual laboratories where the implications of hypotheses about processes over human to geological timescales can be visualized at spatial scales from catchments to mountain ranges.

Major geological events and uranium metallogenesis in South-west China

International Nuclear Information System (INIS)

Zhang Chengjiang; Xu Zhengqi; Ni Shijun; Chen Youliang

2012-01-01

Uranium is widely distributed in South-west China, with all types but on a not-so-large scale. South-west China is located on the combining site of several large tectonic elements and every tectonic movement has different effects on different regions. To study and clarify the correlation between the major geological events in South-west China and the Uranium metallogenesis, comprehensive research and field investigation are made besides collecting a lot of materials. Through analysis and research on the major geological events in South-west China, the evolution of those e vents is basically clarified and the events closely related with uranium mineralization are determined. It is discovered that there are several ore-forming geologic events in the geological history of South-west China; almost every major tectonic movement cycle is accompanied with uranium metallogenesis, from Jinning Movement to Chengjiang Movement, to Hercynian Movement, to Indosinian Movement. to Yanshan Movement. to Himalayan movement. Even though every major tectonic cycle is accompanied with uranium mineralization, three major geological events are generally obviously related with uranium metallogenesis, i.e. the Rodinian supercontinent breakup even in Jinning-Chengjiang Period, Yanshan Movement and Himalayan movement, in which the first one is the process of uranium pre-enrichment and provides the source of uranium. Yanshan Movement and Himalayan movement are the important processes for mineralization, mainly the hydrothermal superimposed mineralization. (authors)

A 3D geological and geomechanical model of the 1963 Vajont landslide

Science.gov (United States)

Bistacchi, Andrea; Massironi, Matteo; Francese, Roberto; Giorgi, Massimo; Chistolini, Filippo; Battista Crosta, Giovanni; Castellanza, Riccardo; Frattini, Paolo; Agliardi, Federico; Frigerio, Gabriele

2014-05-01

The Vajont rockslide has been the object of several studies because of its catastrophic consequences and particular evolution. Several qualitative or quantitative models have been presented in the last 50 years, but a complete explanation of all relevant geological and mechanical processes remains elusive. In order to better understand the mechanics and dynamics of the 1963 event, we have reconstructed the first 3D geological model of the rockslide, which allowed us to accurately investigate the rockslide structure and kinematics. The input data for the model consisted in: pre- and post-rockslide geological maps, pre- and post-rockslide orthophotos, pre- and post-rockslide digital elevation models, structural data, boreholes, and geophysical data (2D and 3D seismics and resistivity). All these data have been integrated in a 3D geological model implemented in Gocad®, using the implicit surface modelling method. Results of the 3D geological model include the depth and geometry of the sliding surface, the volume of the two lobes of the rockslide accumulation, kinematics of the rockslide in terms of the vector field of finite displacement, and high quality meshes useful for mechanical and hydrogeological simulations. The latter can include information about the stratigraphy and internal structure of the rock masses and allow tracing the displacement of different material points in the rockslide from the pre-1963-failure to the post-rockslide state. As a general geological conclusion, we may say that the 3D model allowed us to recognize very effectively a sliding surface, whose non-planar geometry is affected by the interference pattern of two regional-scale fold systems. The rockslide is partitioned into two distinct and internally continuous rock masses with a distinct kinematics, which were characterised by a very limited internal deformation during the slide. The continuity of these two large blocks points to a very localized deformation, occurring along a thin

A geological history of reflecting optics.

Science.gov (United States)

Parker, Andrew Richard

2005-03-22

Optical reflectors in animals are diverse and ancient. The first image-forming eye appeared around 543 million years ago. This introduced vision as a selection pressure in the evolution of animals, and consequently the evolution of adapted optical devices. The earliest known optical reflectors--diffraction gratings--are 515 Myr old. The subsequent fossil record preserves multilayer reflectors, including liquid crystals and mirrors, 'white' and 'blue' scattering structures, antireflective surfaces and the very latest addition to optical physics--photonic crystals. The aim of this article is to reveal the diversity of reflecting optics in nature, introducing the first appearance of some reflector types as they appear in the fossil record as it stands (which includes many new records) and backdating others in geological time through evolutionary analyses. This article also reveals the commercial potential for these optical devices, in terms of lessons from their nano-level designs and the possible emulation of their engineering processes--molecular self-assembly.

The development and evolution of landform based on neotectonic ...

Indian Academy of Sciences (India)

Lingmin Zhong

2018-02-14

Feb 14, 2018 ... involving integration of data from the aspects of structural geology ... regions is very sensitive to crustal movement such as folding and faulting ...... drainage network evolution in the upper Narmada Valley: Implication to ...

A low-angle normal fault and basement structures within the Enping Sag, Pearl River Mouth Basin: Insights into late Mesozoic to early Cenozoic tectonic evolution of the South China Sea area

Science.gov (United States)

Ye, Qing; Mei, Lianfu; Shi, Hesheng; Shu, Yu; Camanni, Giovanni; Wu, Jing

2018-04-01

The basement structure of the Cenozoic Enping Sag, within the Pearl River Mouth Basin on the northern margin of South China Sea, is revealed by borehole-constrained high-quality 3D seismic reflection data. Such data suggest that the Enping Sag is bounded in the north by a low-angle normal fault. We interpret this low-angle normal fault to have developed as the result of the reactivation of a pre-existing thrust fault part of a pre-Cenozoic thrust system. This is demonstrated by the selective reactivation of the pre-existing thrust and by diffuse contractional deformation recognized from the accurate analysis of basement reflections. Another significant result of this study is the finding of some residual rift basins within the basement of the Enping Sag. Both the thrust system and the residual basins are interpreted to have developed after the emplacement of continental margin arc-related granitoids (J3-K1) that define the basement within the study area. Furthermore, seismic sections show that the pre-existing residual rift basins are offset by the main thrust fault and they are both truncated by the Tg unconformity. These structural relationships, interpreted in the frame of previous studies, help us to reconstruct a six-event structural evolution model for the Enping Sag from the late Mesozoic to the early Cenozoic. In particular, we interpret the residual rift basins to have formed as the result of back-arc extension due to the slab roll-back of the Paleo-Pacific Plate subduction in the early K2. The thrust system has recorded a compressional event in the late K2 that followed the back-arc extension in the SCS area. The mechanism of this compressional event is still to be clarified, and might be related to continuous subduction of the Paleo-Pacific Plate or to the continent-continent collision between a micro-continental block and the South China margin.

Early to Middle Jurassic tectonic evolution of the Bogda Mountains, Northwest China: Evidence from sedimentology and detrital zircon geochronology

Science.gov (United States)

Ji, Hongjie; Tao, Huifei; Wang, Qi; Qiu, Zhen; Ma, Dongxu; Qiu, Junli; Liao, Peng

2018-03-01

The Bogda Mountains, as an important intracontinental orogenic belt, are situated in the southern part of the Central Asian Orogenic Belt (CAOB), and are a key area for understanding the Mesozoic evolution of the CAOB. However, the tectonic evolution of the Bogda Mountains remains controversial during the Mesozoic Era, especially the Early to Middle Jurassic Periods. The successive Lower to Middle Jurassic strata are well preserved and exposed along the northern flank of the Western Bogda Mountains and record the uplift processes of the Bogda Mountains. In this study, we analysed sedimentary facies combined with detrital zircon U-Pb geochronology at five sections of Lower to Middle Jurassic strata to detect the tectonic evolution and changes of provenance in the Bogda area. During Early to Middle Jurassic times, the fluvial, deltaic and lacustrine environments dominated in the western section of the Bogda area. The existence of Early Triassic peak age indicates that the Bogda Mountains did not experience uplift during the period of early Badaowan Formation deposition. The Early Triassic to Late Permian granitoid plutons and Carboniferous volcanic rocks from the Barkol and Santanghu areas were the main provenances. The significant change in the U-Pb age spectrum implies that the Eastern Bogda Mountains initiated uplift in the period of late Badaowan Formation deposition, and the Eastern Junggar Basin and the Turpan-Hami Basin were partially partitioned. The Eastern Bogda Mountains gradually became the major provenance. From the period of early Sangonghe to early Toutunhe Formations deposition, the provenance of the sediments and basin-range frame were similar to that of late Badaowan. However, the Eastern Bogda Mountains suffered intermittent uplift three times, and successive denudation. The uplifts respectively happened in early Sangonghe, late Sangonghe to early Xishanyao, and late Xishanyao to early Toutunhe. During the deposition stage of Toutunhe Formation, a

New insights into the distribution and evolution of the Cenozoic Tan-Lu Fault Zone in the Liaohe sub-basin of the Bohai Bay Basin, eastern China

Science.gov (United States)

Huang, Lei; Liu, Chi-yang; Xu, Chang-gui; Wu, Kui; Wang, Guang-yuan; Jia, Nan

2018-01-01

As the largest strike-slip fault system in eastern China, the northeast-trending Tan-Lu Fault Zone (TLFZ) is a significant tectonic element contributing to the Mesozoic-Cenozoic regional geologic evolution of eastern Asia, as well as to the formation of ore deposits and oilfields. Because of the paucity of data, its distribution and evolutionary history in the offshore Liaohe sub-basin of the northern Bohai Bay Basin (BBB) are still poorly understood. Investigations of the strike-slip fault system in the western portion of the offshore Liaohe sub-basin via new seismic data provide us with new insights into the characteristics of the Cenozoic TLFZ. Results of this study show that Cenozoic dextral strike-slip faults occurred near the center of the Liaoxi graben in the offshore Liaohe sub-basin; these strike-slip faults connect with their counterparts to the north, the western part of the onshore Liaohe sub-basin, and have similar characteristics to those in other areas of the BBB in terms of kinematics, evolutionary history, and distribution; consequently, these faults are considered as the western branch of the TLFZ. All strike-slip faults within the Liaoxi graben merge at depth with a central subvertical basement fault induced by the reactivation of a pre-existing strike-slip basement fault, the pre-Cenozoic TLFZ. Data suggest that the TLFZ across the whole Liaohe sub-basin comprises two branches and that the Cenozoic distribution of this system was inherited from the pre-Cenozoic TLFZ. This characteristic distribution might be possessed by the whole TLFZ, thus the new understandings about the distribution and evolutionary model of the TLFZ in this study can be inferred in many research fields along the whole fault zone, such as regional geology, ore deposits, petroleum exploration and earthquake hazard.

Geological research for public outreach and education in Lithuania

Science.gov (United States)

Skridlaite, Grazina; Guobyte, Rimante

2013-04-01

Successful IYPE activities and implementation of Geoheritage day in Lithuania increased public awareness in geology. A series of projects introducing geology to the general public and youth, supported by EU funds and local communities, were initiated. Researchers from the scientific and applied geology institutions of Lithuania participated in these projects and provided with the geological data. In one case, the Lithuanian Survey of Protected Areas supported the installation of a series of geological exhibitions in several regional and national parks. An animation demonstrating glacial processes was chosen for most of these because the Lithuanian surface is largely covered with sedimentary deposits of the Nemunas (Weichselian) glaciation. Researchers from the Lithuanian Geological Survey used the mapping results to demonstrate real glacial processes for every chosen area. In another case, 3D models showing underground structures of different localities were based on detailed geological maps and profiles obtained for that area. In case of the Sartai regional park, the results of previous geological research projects provided the possibility to create a movie depicting the ca. 2 Ga geological evolution of the region. The movie starts with the accretion of volcanic island arcs on the earlier continental margin at ca. 2 Ga and deciphers later Precambrian tectonic and magmatic events. The reconstruction is based on numerous scientific articles and interpretation of geophysical data. Later Paleozoic activities and following erosion sculptured the surface which was covered with several ice sheets in Quaternary. For educational purpose, a collection of minerals and rocks at the Forestry Institute was used to create an exhibition called "Cycle of geological processes". Forestry scientists and their students are able to study the interactions of geodiversity and biodiversity and to understand ancient and modern geological processes leading to a soil formation. An aging

Viviparity and K-selected life history in a Mesozoic marine plesiosaur (Reptilia, Sauropterygia).

Science.gov (United States)

O'Keefe, F R; Chiappe, L M

2011-08-12

Viviparity is known in several clades of Mesozoic aquatic reptiles, but evidence for it is lacking in the Plesiosauria. Here, we report a Late Cretaceous plesiosaur fossil consisting of a fetus preserved within an adult of the same taxon. We interpret this occurrence as a gravid female and unborn young and hence as definitive evidence for plesiosaur viviparity. Quantitative analysis indicates that plesiosaurs gave birth to large, probably single progeny. The combination of viviparity, large offspring size, and small brood number differs markedly from the pattern seen in other marine reptiles but does resemble the K-selected strategy of all extant marine mammals and a few extant lizards. Plesiosaurs may have shared other life history traits with these clades, such as sociality and maternal care.

The Mesozoic-Cenozoic igneous intrusions and related sediment-dominated hydrothermal activities in the South Yellow Sea Basin, the Western Pacific continental margin

Science.gov (United States)

Yumao, Pang; Xunhua, Zhang; Guolin, Xiao; Luning, Shang; Xingwei, Guo; Zhenhe, Wen

2018-04-01

Various igneous complexes were identified in multi-channel seismic reflection profiles from the South Yellow Sea Basin. It is not rare that magmatic intrusions in sedimentary basins cause strong thermal perturbations and hydrothermal activities. Some intrusion-related hydrothermal vent complexes have been identified and they are considered to originate from the deep sedimentary contact aureole around igneous intrusions and terminate in upper vents structures, and are linked by a vertical conduit system. The upper vent complexes are usually eye-shaped, dome-shaped, fault-related, crater-shaped or pock-shaped in seismic profiles. A schematic model was proposed to illustrate the structures of different types of hydrothermal vent complexes. A conceptual conduit model composed of an upper pipe-like part and a lower branching part was also derived. Hydrothermal vent complexes mainly developed during the Middle-Late Cretaceous, which is coeval with, or shortly after the intrusion. The back-arc basin evolution of the area which is related to the subduction of the Paleo-Pacific plate during the Mesozoic-Cenozoic may be the principal factor for voluminous igneous complexes and vent complexes in this area. It is significant to study the characteristics of igneous complexes and related hydrothermal vent complexes, which will have implications for the future study of this area.

Uranium geochemistry, mineralogy, geology, exploration and resources

International Nuclear Information System (INIS)

De Vivo, B.

1984-01-01

This book comprises papers on the following topics: history of radioactivity; uranium in mantle processes; transport and deposition of uranium in hydrothermal systems at temperatures up to 300 0 C: Geological implications; geochemical behaviour of uranium in the supergene environment; uranium exploration techniques; uranium mineralogy; time, crustal evolution and generation of uranium deposits; uranium exploration; geochemistry of uranium in the hydrographic network; uranium deposits of the world, excluding Europe; uranium deposits in Europe; uranium in the economics of energy; role of high heat production granites in uranium province formation; and uranium deposits

Geologic Mapping, Volcanic Stages and Magmatic Processes in Hawaiian Volcanoes

Science.gov (United States)

Sinton, J. M.

2005-12-01

The concept of volcanic stages arose from geologic mapping of Hawaiian volcanoes. Subaerial Hawaiian lava successions can be divided generally into three constructional phases: an early (shield) stage dominated by thin-bedded basaltic lava flows commonly associated with a caldera; a later (postshield) stage with much thicker bedded, generally lighter colored lava flows commonly containing clinopyroxene; calderas are absent in this later stage. Following periods of quiescence of a half million years or more, some Hawaiian volcanoes have experienced renewed (rejuvenated) volcanism. Geological and petrographic relations irrespective of chemical composition led to the identification of mappable units on Niihau, Kauai, Oahu, Molokai, Maui and Hawaii, which form the basis for this 3-fold division of volcanic activity. Chemical data have complicated the picture. There is a growing tendency to assign volcanic stage based on lava chemistry, principally alkalicity, into tholeiitic shield, alkalic postshield, and silica undersaturated rejuvenation, despite the evidence for interbedded tholeiitic and alkalic basalts in many shield formations, and the presence of mildly tholeiitic lavas in some postshield and rejuvenation formations. A consistent characteristic of lava compositions from most postshield formations is evidence for post-melting evolution at moderately high pressures (3-7 kb). Thus, the mapped shield to postshield transitions primarily reflect the disappearance of shallow magma chambers (and associated calderas) in Hawaiian volcanoes, not the earlier (~100 ka earlier in Waianae Volcano) decline in partial melting that leads to the formation of alkalic parental magmas. Petrological signatures of high-pressure evolution are high-temperature crystallization of clinopyroxene and delayed crystallization of plagioclase, commonly to <3 % MgO. Petrologic modeling using pMELTS and MELTS algorithms allows for quantification of the melting and fractionation conditions giving

New constraints on the tectonic and thermal evolution of the Central-Western Carpathians

Science.gov (United States)

Castelluccio, Ada; Andreucci, Benedetta; Grigo, Domenico; Jankowski, Leszek; Ketcham, Richard A.; Mazzoli, Stefano; Szaniawski, Rafal; Zattin, Massimiliano

2014-05-01

The Central-Western Carpathians have been studied for long time but they are a still matter of discussion. In addition, they are one of the principal East European targets for oil and gas exploration. Understanding the tectonic evolution and the spatial and temporal variation of the thermal regime is crucial for this purpose. This orogene formed after the collision between the European Platform and the ALCAPA and Tisza-Dacia microplates from the Upper Jurassic to the Neogene. The widely accepted interpretation suggests the occurrence of the oceanic lithosphere subducting under the two microplates and the development of the oceanic suture in the Pieniny Klippen Belt area during the Paleocene. The subduction ends when the accretionary wedge reaches its present-day position on top of the southern border of the European Platform. The Carpathian arc can be subdivided into three tectonic domains: • Outer Carpathians made up of Upper Jurassic to Lower Miocene siliciclastic deposits intercalated with shales and sandstones; • Pieniny Klippen Belt formed by Mesozoic olistoliths and olistostromes in a sandy-clay Cretaceous sheared matrix; • Inner Carpathians consisting in Variscan allochthonous crystalline basement with its Mesozoic cover involved in the late Cretaceous folding and thrusting These deposits are unconformably overlain by the undeformed Central Carpathian Paleogene Basin successions. Cross-section balancing and sequential restoration integrated with low-temperature thermochronometry (apatite fission track and apatite (U-Th-Sm)/He analysis) can better constrain the tectonic evolution of this area and, in particular, its exhumation history. Seven balanced sections have been constructed across the Polish and Ukrainian Carpathians. The sequential restoration shows a thick-skinned tectonics during the Upper Cretaceous, involving the Inner Carpathian basin. The erosion of the Mesozoic basement cover and the sedimentation of these deposits in the foreland basin

Origins of Sinuous and Braided Channels on Ascraeus Mons, Mars - A Keck Geology Consortium Undergraduate Research Project

Science.gov (United States)

de Wet, A. P.; Bleacher, J. E.; Garry, W. B.

2012-01-01

Water has clearly played an important part in the geological evolution of Mars. There are many features on Mars that were almost certainly formed by fluvial processes -- for example, the channels Kasei Valles and Ares Vallis in the Chryse Planitia area of Mars are almost certainly fluvial features. On the other hand, there are many channel features that are much more difficult to interpret -- and have been variously attributed to volcanic and fluvial processes. Clearly unraveling the details of the role of water on Mars is extremely important, especially in the context of the search of extinct or extant life. In this project we built on our recent work in determining the origin of one channel on the southwest rift apron of Ascraeus Mons. This project, funded by the Keck Geology Consortium and involving 4 undergraduate geology majors took advantage of the recently available datasets to map and analyze similar features on Ascraeus Mons and some other areas of Mars. A clearer understanding of how these particular channel features formed might lead to the development of better criteria to distinguish how other Martian channel features formed. Ultimately this might provide us with a better understanding of the role of volcanic and fluvial processes in the geological evolution of Mars.

Osmium Isotopic Evolution of the Mantle Sources of Precambrian Ultramafic Rocks

Science.gov (United States)

Gangopadhyay, A.; Walker, R. J.

2006-12-01

The Os isotopic composition of the modern mantle, as recorded collectively by ocean island basalts, mid- oceanic ridge basalts (MORB) and abyssal peridotites, is evidently highly heterogeneous (γ Os(I) ranging from +25). One important question, therefore, is how and when the Earth's mantle developed such large-scale Os isotopic heterogeneities. Previous Os isotopic studies of ancient ultramafic systems, including komatiites and picrites, have shown that the Os isotopic heterogeneity of the terrestrial mantle can be traced as far back as the late-Archean (~ 2.7-2.8 Ga). This observation is based on the initial Os isotopic ratios obtained for the mantle sources of some of the ancient ultramafic rocks determined through analyses of numerous Os-rich whole-rock and/or mineral samples. In some cases, the closed-system behavior of these ancient ultramafic rocks was demonstrated via the generation of isochrons of precise ages, consistent with those obtained from other radiogenic isotopic systems. Thus, a compilation of the published initial ^{187}Os/^{188}Os ratios reported for the mantle sources of komatiitic and picritic rocks is now possible that covers a large range of geologic time spanning from the Mesozoic (ca. 89 Ma Gorgona komatiites) to the Mid-Archean (e.g., ca. 3.3 Ga Commondale komatiites), which provides a comprehensive picture of the Os isotopic evolution of their mantle sources through geologic time. Several Precambrian komatiite/picrite systems are characterized by suprachondritic initial ^{187}Os/^{188}Os ratios (e.g., Belingwe, Kostomuksha, Pechenga). Such long-term enrichments in ^{187}Os of the mantle sources for these rocks may be explained via recycling of old mafic oceanic crust or incorporation of putative suprachondritic outer core materials entrained into their mantle sources. The relative importance of the two processes for some modern mantle-derived systems (e.g., Hawaiian picrites) is an issue of substantial debate. Importantly, however, the

A bibliography of planetary geology principal investigators and their associates, 1982 - 1983

Science.gov (United States)

Plescia, J. B.

1984-01-01

This bibliography cites recent publications by principal investigators and their associates, supported through NASA's Office of Space Science and Applications, Earth and Planetary Exploration Division, Planetary Geology Program. It serves as a companion piece to NASA TM-85127, ""Reports of Planetary Programs, 1982". Entries are listed under the following subject areas: solar system, comets, asteroids, meteorites and small bodies; geologic mapping, geomorphology, and stratigraphy; structure, tectonics, and planetary and satellite evolutions; impact craters; volcanism; fluvial, mass wasting, glacial and preglacial studies; Eolian and Arid climate studies; regolith, volatiles, atmosphere, and climate, radar; remote sensing and photometric studies; and cartography, photogrammetry, geodesy, and altimetry. An author index is provided.

Early Tertiary magmatism and probable Mesozoic fabrics in the Black Mountains, Death Valley, California

Science.gov (United States)

Miller, Martin G.; Friedman, Richard M.

1999-01-01

We report two early Tertiary U-Pb zircon ages for pegmatite from the Black Mountains of Death Valley, California. These ages, 54.7 ± 0.6 Ma and 56 ± 3 Ma, are unique for much of southeastern California. The samples belong to a pegmatite suite that occupies part of the footwall of the Badwater turtleback, a late Tertiary extensional feature; similar but undated pegmatite intrudes the footwalls of the Copper Canyon and Mormon Point turtlebacks farther south. The pegmatite suite demonstrates that fabric development on the turtlebacks was at least a two-stage process. Fabrics cut by these pegmatites likely formed during the Mesozoic, whereas those that involve them formed during late Tertiary extension.

The deep geologic repository technology programme: toward a geoscience basis for understanding repository safety

International Nuclear Information System (INIS)

Jensen, M.R.

2007-01-01

Within the Deep Geologic Repository Technology Programme (DGRTP) several Geoscience activities are focused on advancing the understanding of groundwater flow system evolution and geochemical stability in a Canadian Shield setting as affected by long-term climate change. A key aspect is developing confidence in predictions of groundwater flow patterns and residence times as they relate to the safety of a deep geologic repository for used nuclear fuel waste. This is being achieved through a coordinated multi-disciplinary approach intent on: i) demonstrating coincidence between independent geo-scientific data; ii) improving the traceability of geo-scientific data and its interpretation within a conceptual descriptive model(s); iii) improving upon methods to assess and demonstrate robustness in flow domain prediction(s) given inherent flow domain uncertainties (i.e. spatial chemical/physical property distributions, boundary conditions) in time and space; and iv) improving awareness amongst geo-scientists as to the utility of various geo-scientific data in supporting a safety case for a deep geologic repository. This multi-disciplinary DGRTP approach is yielding an improved understanding of groundwater flow system evolution and stability in Canadian Shield settings that is further contributing to the geo-scientific basis for understanding and communicating aspects of DGR safety. (author)

Mountains, glaciers, and mines—The geological story of the Blue River valley, Colorado, and its surrounding mountains

Science.gov (United States)

Kellogg, Karl; Bryant, Bruce; Shroba, Ralph R.

2016-02-10

This report describes, in a nontechnical style, the geologic history and mining activity in the Blue River region of Colorado, which includes all of Summit County. The geologic story begins with the formation of ancient basement rocks, as old as about 1700 million years, and continues with the deposition of sedimentary rocks on a vast erosional surface beginning in the Cambrian Period (about 530 million years ago). This deposition was interrupted by uplift of the Ancestral Rocky Mountains during the late Paleozoic Era (about 300 million years ago). The present Rocky Mountains began to rise at the close of the Mesozoic Era (about 65 million years ago). A few tens of millions years ago, rifting began to form the Blue River valley; a major fault along the east side of the Gore Range dropped the east side down, forming the present valley. The valley once was filled by sediments and volcanic rocks that are now largely eroded. During the last few hundred-thousand years, at least two periods of glaciation sculpted the mountains bordering the valley and glaciers extended down the Blue River valley as far south as present Dillon Reservoir. Discovery of deposits of gold, silver, copper, and zinc in the late 1800s, particularly in the Breckenridge region, brought an influx of early settlers. The world-class molybdenum deposit at Climax, mined since the First World War, reopened in 2012 after a period of closure.

Synthetic geology - Exploring the "what if?" in geology

Science.gov (United States)

Klump, J. F.; Robertson, J.

2015-12-01

The spatial and temporal extent of geological phenomena makes experiments in geology difficult to conduct, if not entirely impossible and collection of data is laborious and expensive - so expensive that most of the time we cannot test a hypothesis. The aim, in many cases, is to gather enough data to build a predictive geological model. Even in a mine, where data are abundant, a model remains incomplete because the information at the level of a blasting block is two orders of magnitude larger than the sample from a drill core, and we have to take measurement errors into account. So, what confidence can we have in a model based on sparse data, uncertainties and measurement error? Synthetic geology does not attempt to model the real world in terms of geological processes with all their uncertainties, rather it offers an artificial geological data source with fully known properties. On the basis of this artificial geology, we can simulate geological sampling by established or future technologies to study the resulting dataset. Conducting these experiments in silico removes the constraints of testing in the field or in production, and provides us with a known ground-truth against which the steps in a data analysis and integration workflow can be validated.Real-time simulation of data sources can be used to investigate crucial questions such as the potential information gain from future sensing capabilities, or from new sampling strategies, or the combination of both, and it enables us to test many "what if?" questions, both in geology and in data engineering. What would we be able to see if we could obtain data at higher resolution? How would real-time data analysis change sampling strategies? Does our data infrastructure handle many new real-time data streams? What feature engineering can be deducted for machine learning approaches? By providing a 'data sandbox' able to scale to realistic geological scenarios we hope to start answering some of these questions.

Scientific reference on the long time evolution of spent fuels; Referentiel scientifique sur l'evolution a long terme des combustibles uses

Energy Technology Data Exchange (ETDEWEB)

Ferry, C.; Poinssot, Ch.; Broudic, V.; Jegou, Ch.; Roudil, D.; Poulesquen, A.; Miserque, F. [CEA Saclay, Dept. de Physico-Chimie, 91 - Gif sur Yvette (France); Cappelaere, Ch. [CEA Saclay, Dept. des Materiaux pour le Nucleaire, 91 - Gif-sur-Yvette (France); Desgranges, L.; Garcia, Ph.; Piron, J.P. [CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. d' Etudes des Combustibles; Lovera, P.; Marimbeau, P. [CEA Cadarache, 13 - Saint Paul lez Durance (France). Dept. d' Etudes des Reacteurs; Corbel, C. [CEA Saclay, Dept. de Recherche sur l' Etat Condense, les Atomes et les Molecules, 91 - Gif sur Yvette (France)

2005-03-15

This report is published in the framework of the 1991 French law for the nuclear waste management. The state of the art reported here concerns the long term evolution of spent fuel in the various environmental conditions corresponding to dry storage and geological disposal: closed system, air and water saturated medium. This review is based on the results of the french PRECCI project (Research Program on Long term Evolution of Spent Nuclear Fuel) and on literature data. (authors)

Mesozoic dinosaurs from Brazil and their biogeographic implications

Directory of Open Access Journals (Sweden)

Jonathas S. Bittencourt

2011-03-01

Full Text Available The record of dinosaur body-fossils in the Brazilian Mesozoic is restricted to the Triassic of Rio Grande do Sul and Cretaceous of various parts of the country. This includes 21 named species, two of which were regarded as nomina dubia, and 19 consensually assigned to Dinosauria. Additional eight supraspecific taxa have been identified based on fragmentary specimens and numerous dinosaur footprints known in Brazil. In fact, most Brazilian specimens related to dinosaurs are composed of isolated teeth and vertebrae. Despite the increase of fieldwork during the last decade, there are still no dinosaur body-fossils of Jurassic age and the evidence of ornithischians in Brazil is very limited. Dinosaur faunas from this country are generally correlated with those from other parts of Gondwana throughout the Mesozoic. During the Late Triassic, there is a close correspondence to Argentina and other south-Pangaea areas. Mid-Cretaceous faunas of northeastern Brazil resemble those of coeval deposits of North Africa and Argentina. Southern hemisphere spinosaurids are restricted to Africa and Brazil, whereas abelisaurids are still unknown in the Early Cretaceous of the latter. Late Cretaceous dinosaur assemblages of south-central Brazil are endemic only to genus or, more conspicuously, to species level, sharing closely related taxa with Argentina, Madagascar, Indo-Pakistan and, to a lesser degree, continental Africa.O registro osteológico de dinossauros no Mesozóico brasileiro está restrito a rochas triássicas do Rio Grande do Sul e estratos cretáceos de várias partes do país. Isto inclui 21 espécies nominais, sendo duas referidas como nomina dubia, e 19 consensualmente classificadas como dinossauros. Oito táxons supraespecíficos adicionais baseados em material fragmentado e diversas pegadas são conhecidos no Brasil. De fato, a maior parte dos espécimes é composta de dentes isolados e vértebras. Apesar do aumento em trabalhos de campo na última

Ecosystems past: prehistory of California vegetation

Science.gov (United States)

C.I. Millar; W.B. Woolfenden

2016-01-01

The history of California's vegetation, from origins in the Mesozoic through Quaternary is outlined. Climatic and geologic history and the processes driving changes in vegetation over time are also described. 

Isotopic data bearing on the origin of Mesozoic and Tertiary granitic rocks in the western United States

International Nuclear Information System (INIS)

DePaolo, D.J.; Farmer, G.L.

1984-01-01

A regional survey of initial Nd and Sr isotopic compositions has been done on Mesozoic and Tertiary granitic rocks from a 500 000 km 2 area in California, Nevada, Utah, Arizona, and Colorado. The plutons, which range in composition from quartz diorite to monzogranite, are intruded into accreted oceanic geosynclinal terrains in the west and north and into Precambrian basement in the east. Broad geographic coverage allows the data to be interpreted in the context of the regional pre-Mesozoic crustal structure. Initial Nd isotopic compositions exhibit a huge range, encompassing values typical of oceanic magmatic arcs and Archean basement. The sources of the magmas can be inferred from the systematic geographic variability of Nd isotopic compositions. The plutons in the accreted terrains represent mantle-derived magma that assimilated crust while differentiating at deep levels. Those emplaced into Precambrian basement are mainly derived from the crust. The regional patterns can be understood in terms of: (1) the flux of mantle magma entering the crust; (2) crustal thickness; and (3) crustal age. The mantle magma flux apparently decreased inland; in the main batholith belts purely crustal granitic rocks are not observed because the flux was too large. Inland, crustal granite is common because mantle magma was scarce and the crust was thick, and hot enough to melt. The epsilonsub(Nd) values of peraluminous granite formed by melting of the Precambrian basement depend on the age of the local basement source. (author)

Structure and geological evolution of the bedrock at southern Satakunta, SW Finland

International Nuclear Information System (INIS)

Paulamaeki, S.; Paananen, M.; Elo, S.

2002-02-01

The southern Satakunta area lies on the west coast of Finland, mainly covering the mainland (with main towns Pori and Rauma), but also including the coastal archipelago and part of the Bothnian Sea. Near the centre of the area lies the island of Olkiluoto, on which Finland's site for a deep repository for spent nuclear fuel is located. The purpose of the present report is to compile and interpret all available geological and geophysical data relevant to understanding the regional geological setting of the Olkiluoto site. The area described is covered by four 1:100 000 scale geological map sheets, published by the Geological Survey of Finland, which, together with low-altitude aeromagnetic maps, provide the basis for a new 1:250 000 geological map compilation. This shows that the bedrock of southern Satakunta can be subdivided into three main zones: a pelitic migmatite belt in the southwest, a central, NW-SE trending area of sandstone, and a psammitic migmatite belt in the northeast. The migmatite belts formed during the Svecofennian orogeny, 1900-1800 Ma ago (Palaeoproterozoic). The sandstone area is the remnant of an alluvial basin, preserved now in a NW-SE trending graben, bounded on both sides by normal fault zones. The sandstones are thought to be at least 1400-1300 Ma old (Mesoproterozoic), and they are cut by Postjotnian olivine diabase dykes, 1270-1250 Ma in age. The Svecofennian migmatite belts show a complex history of formation, with various phases of anatexis/metamorphism, deformation and intrusion. In the pelitic migmatite belt, in which the Olkiluoto site is situated, four phases of ductile deformation (D-D4) and two phases of regional highT/lowP metamorphism and migmatite formation can be recognised, together with synorogenic (tonalite, granodiotite) and late orogenic ( potassium granite) intrusions. Subsequently, this very heterogeneous complex was intruded by anorogenic rapakivi granites, with ages 1580-1550 Ma. One pluton, the Eurajoki stock

The indentification of Jueluotage V-type structure in Xinjiang and its orderness

International Nuclear Information System (INIS)

Fang Maolong; Sun Wenpeng; Cai Wenbo; Xu Daoyi

2005-01-01

Based on the interpretation of satellite image and field checking in Jueluotage area, Xinjiang, it is thought that the sublatitudinal arc fault zones have been formed since Mesozoic through the evolution of the NWW-trending and NEE-trending faults occurring in pre-Mesozoic time. These three sets of faults comprise the Jueluotage 'V-type structure' formed by the NW-trending structural stress field and drastically activated since Neocene. The Jueluotage V-type structure is expressed in time as an ordered process, and in space as an ordered arrangement and an ordered evolution direction, and characterizes the Information Ordered Series (IOS) of the evolution process of fault structure. (authors)

Lunar Geologic Mapping: A Preliminary Map of a Portion of the LQ-10 ("Marius") Quadrangle

Science.gov (United States)

Gregg, T. K. P.; Yingst, R. A.

2009-01-01

Since the first lunar mapping program ended in the 1970s, new topographical, multispectral, elemental and albedo imaging datasets have become available (e.g., Clementine, Lunar Prospector, Galileo). Lunar science has also advanced within the intervening time period. A new systematic lunar geologic mapping effort endeavors to build on the success of earlier mapping programs by fully integrating the many disparate datasets using GIS software and bringing to bear the most current understanding of lunar geologic history. As part of this program, we report on a 1:2,500,000-scale preliminary map of a subset of Lunar Quadrangle 10 ("LQ-10" or the "Marius Quadrangle," see Figures 1 and 2), and discuss the first-order science results. By generating a geologic map of this region, we can constrain the stratigraphic and geologic relationships between features, revealing information about the Moon s chemical and thermal evolution.

Assessment of Environmental Factors of Geology on Waste and Engineering Barriers for Waste Storage Near Surface

International Nuclear Information System (INIS)

Arimuladi SP

2007-01-01

Geological environment factors include features and processes occurring within that spatial and temporal (post-closure) domain whose principal effect is to determine the evolution of the physical, chemical, biological and human conditions of the domain that are relevant to estimating the release and migration of radionuclide and consequent exposure to man. Hardness of radioactive waste and engineer barrier can be decrease by environmental factors. Disposal system domain geological environment factors is a category in the International FEP list and is divided into sub-categories. There are 13 sub-factors of geological environment, 12 sub-factors influence hardness of radioactive waste and engineer barrier, thermal processes and conditions in geosphere can be excluded. (author)

From Tethyan Oceans to the Western Mediterranean I - Plate reconstructions from the Present back to the Early Mesozoic

Science.gov (United States)

Schmid, Stefan; Handy, Mark; Bousquet, Romain; Kissling, Eduard; Bernoulli, Daniel

2010-05-01

A new reconstruction of the branches of Alpine Tethys combines available plate kinematic models of Africa-Europe motion with a wealth of new geological and geophysical data (seismic tomography and paleomagnetics) to shed light the evolution of the Western Mediterranean-Alps system, from sea-floor spreading through subduction to collision. Unlike previous models which relate the fate of Alpine Tethys solely to relative motions of the African plate with respect to Europe during opening of the Atlantic, our reconstruction invokes motions and rotations of four additional and temporarily independent microplates: Adria, Iberia, Alcapia and Alkapecia. Translations and rotations of these microplates with respect to Europe are constrained in the following way: (1) The retro-translations of Adria back to 94 Ma are obtained from shortening estimates in the Alps along geological-geophysical transects of the Alpine orogen and from geobarometric estimates of subduction depth in tectonic units that underwent high-pressure and ultrahigh-pressure metamorphism. Rotations are based on paleomagnetic data of Márton et al. (in press); (2) Iberia follows the motion paths of Savostin et al. (1986), based on magnetic anomalies in the Central and Northern Atlantic; the Corsica-Sardinia block later rifted from Iberia leading to Burdigalian opening of the Liguria-Provençal basin (Serranne 1999). (3) The Alcapia microplate, whose name is derived from the acronym ALCAPA (Alps-Carpathians-Pannonian Basin), separated from Adria in Cretaceous times. Its movement with respect to Adria was absorbed by Cretaceous orogeny in the Eastern Alps, constrained by the Adria-Europe displacement and rotation path; later, during Cenozoic orogeny in the Alps, associated with the closing of the Alpine Tethys, it became part of the Adria microplate again. (4) The introduction of an independent Alkapekia continental fragment and independent microplate during the Late Cenozoic only (Alboran

Tertiary or Mesozoic komatiites from Gorgona Island, Colombia: Field relations and geochemistry

Science.gov (United States)

Echeverría, Lina M.

1980-08-01

An exceptional occurrence of ultramafic lavas within the volcanic member of the Mesozoic (or younger) Gorgona Igneous Complex represents the first known komatiites of post-Precambrian age. Gorgona komatiites are virtually unaltered and display typical spinifex textures, with 7 10 cm long plates of olivine (Fo 88 to 91) surrounded by acicular aluminous augite, subordinate plagioclase (An 56 to 78), basaltic glass, and two spinel phases. The MgO contents of the komatiites range from 15 to 22 wt.%. Sr and Nd isotopic compositions are indicative of depletion of incompatible elements in the mantle source region, as is the case for “normal” mid-ocean ridge basalts. The komatiites are low in total REE abundances and extremely depleted in LREE. They represent primary melts generated by high degree of partial melting of the mantle. Eruption temperatures are estimated at 1,450° to 1,500° C.

Relations between Vegetation and Geologic Framework in Barrier Island

Science.gov (United States)

Smart, N. H.; Ferguson, J. B.; Lehner, J. D.; Taylor, D.; Tuttle, L. F., II; Wernette, P. A.

2017-12-01

Barrier islands provide valuable ecosystems and protective services to coastal communities. The longevity of barrier islands is threatened by sea-level rise, human impacts, and extreme storms. The purpose of this research is to evaluate how vegetation dynamics interact with the subsurface and offshore framework geology to influence the beach and dune morphology. Beach and dune morphology can be viewed as free and/or forced behavior, where free systems are stochastic and the morphology is dependent on variations in the storm surge run-up, aeolian sediment supply and transport potential, and vegetation dynamics and persistence. Forced systems are those where patterns in the coastal morphology are determined by some other structural control, such as the underlying and offshore framework geology. Previous studies have documented the effects of geologic framework or vegetation dynamics on the beach and dunes, although none have examined possible control by vegetation dynamics in context of the geologic framework (i.e. combined free and forced behavior). Padre Island National Seashore (PAIS) was used to examine the interaction of free and forced morphology because the subsurface framework geology and surface beach and dune morphology are variable along the island. Vegetation dynamics were assessed by classifying geographically referenced historical aerial imagery into areas with vegetation and areas without vegetation, as well as LiDAR data to verify this imagery. The subsurface geologic structure was assessed using a combination of geophysical surveys (i.e. electromagnetic induction, ground-penetrating radar, and offshore seismic surveys). Comparison of the observed vegetation patterns and geologic framework leads to a series of questions surrounding how mechanistically these two drivers of coastal morphology are related. Upcoming coring and geophysical surveys will enable us to validate new and existing geophysical data. Results of this paper will help us better

Geological Evolution of the Ganiki Planitia Quadrangle (V14) on Venus

Science.gov (United States)

Grosfils, E. B.; Drury, D. E.; Hurwitz, D. M.; Kastl, B.; Long, s. M.; Richards, J. W.; Venechuk, E. M.

2005-01-01

The Ganiki Planitia quadrangle (25-50degN, 180-210degE) is located north of Atla Regio, south of Vinmara Planitia, and southeast of Atalanta Planitia. The region contains a diverse array of volcanic-, tectonic- and impact-derived features, and the objectives for the ongoing mapping effort are fivefold: 1) explore the formation and evolution of radiating dike swarms within the region, 2) use the diverse array of volcanic deposits to further test the neutral buoyancy hypothesis proposed to explain the origin of reservoir-derived features, 3&4) unravel the volcanic and tectonic evolution in this area, and 5) explore the implications of 1-4 for resurfacing mechanisms. Here we summarize our onging analysis of the material unit stratigraphy in the quadrangle, data central to meeting the aforementioned objectives successfully.

Confidence building in implementation of geological disposal

International Nuclear Information System (INIS)

Umeki, Hiroyuki

2004-01-01

Long-term safety of the disposal system should be demonstrated to the satisfaction of the stakeholders. Convincing arguments are therefore required that instil in the stakeholders confidence in the safety of a particular concept for the siting and design of a geological disposal, given the uncertainties that inevitably exist in its a priori description and in its evolution. The step-wise approach associated with making safety case at each stage is a key to building confidence in the repository development programme. This paper discusses aspects and issues on confidence building in the implementation of HLW disposal in Japan. (author)

Simulation of Anisotropic Rock Damage for Geologic Fracturing

Science.gov (United States)

Busetti, S.; Xu, H.; Arson, C. F.

2014-12-01

model to couple damage evolution with plasticity and with permeability for more geologically realistic simulation.

Microbiological characterization of deep geological compartments

International Nuclear Information System (INIS)

Barsotti, V.; Sergeant, C.; Vesvres, M.H.; Coulon, S.; Joulian, C.; Garrido, F.; Ollivier, B.

2012-01-01

Document available in extended abstract form only. Microbial life in deep sediments and Earth's crust is now acknowledged by the scientific world. The deep subsurface biosphere contributes significantly to fundamental biogeochemical processes. However, despite great advances in geo-microbiological studies, deep terrestrial ecosystems are microbiologically poorly understood, mainly due to their inaccessibility. The drilling down to the base of the Triassic (1980 meters deep) in the geological formations of the eastern Paris Basin performed by ANDRA (EST433) in 2008 provides us a good opportunity to explore the deep biosphere. We conditioned the samples on the coring site, in as aseptic conditions as possible. In addition to storage at atmospheric pressure, a portion of the four Triassic samples was placed in a 190 bars pressurized chamber to investigate the influence of the conservation pressure factor on the found microflora. In parallel, in order to evaluate a potential bacterial contamination of the cores by the drilling fluids, samples of mud just before each sample drilling were taken and analyzed. The microbial exploration can be divided in two parts: - A cultural approach in different culture media for metabolic groups as methanogens, fermenters and sulphate reducing bacteria to stimulate their growth and to isolate microbial cells still viable. - A molecular approach by direct extraction of genomic DNA from the geological samples to explore a larger biodiversity. The limits are here the difficulties to extract DNA from these low biomass containing rocks. After comparison and optimization of several DNA extraction methods, the bacterial diversity present in rock cores was analyzed using DGGE (Denaturating Gel Gradient Electrophoresis) and cloning. The detailed results of all these investigations will be presented: - Despite all 400 cultural conditions experimented (with various media, salinities, temperatures, conservation pressure, agitation), no viable and

Structural Framework and Architecture of the Paleoproterozoic Bryah and Padbury Basins from Integrated Potential Field and Geological Datasets: Towards an Understanding of the Basin Evolution

Science.gov (United States)

Nigro R A Ramos, L.; Aitken, A.; Occhipinti, S.; Lindsay, M.

2017-12-01

The Bryah and Padbury Basins were developed along the northern margin of the Yilgarn Craton, in the southern portion of the Capricorn Orogen, which represents a Proterozoic tectonic zone that bounds the Yilgarn and Pilbara Cratons in Western Australia. These basins have been previously interpreted as developing in a rift, back-arc, and retro-arc foreland basins. Recent studies suggest that the Bryah Basin was deposited in a rift setting, while the overlying Padbury Basin evolved in a pro-foreland basin during the collision of the Yilgarn Craton and the Pilboyne block (formed by the Pilbara Craton and the Glenburgh Terrane), occurring in the Glenburgh Orogeny (2005-1960 Ma). This study focuses on characterizing the architecture and structural framework of the Bryah and Padbury Basins through analysis of geophysical and geological datasets, in order to better understand the different stages of the basins evolution. Gravity and magnetic data were used to define the main tectonic units and lithological boundaries, and to delineate major discontinuities in the upper and lower crust, as well as anomalies through a combination of map view interpretation and forward modelling. Geological mapping and drill core observations were linked with the geophysical interpretations. Fourteen magnetic domains are distinguished within the basins, while four main domains based on the Bouguer Anomaly are recognized. The highest gravity amplitude is related with an anomaly trending EW/NE-SW, which is coincident with the voluminous mafic rocks of the Bryah Basin, and may indicate the presence of an approximately 5km thick package of higher density mafic rocks. Magnetic depth estimations also indicate deep magnetic sources up to approximately 4,45km. These results can help to elucidate processes that occurred during the precursor rift of the early stages of the Bryah Basin, add information in relation to the basement control on sedimentation, allow the characterization of the varying

The Pilot Lunar Geologic Mapping Project: Summary Results and Recommendations from the Copernicus Quadrangle

Science.gov (United States)

Skinner, J. A., Jr.; Gaddis, L. R.; Hagerty, J. J.

2010-01-01

The first systematic lunar geologic maps were completed at 1:1M scale for the lunar near side during the 1960s using telescopic and Lunar Orbiter (LO) photographs [1-3]. The program under which these maps were completed established precedents for map base, scale, projection, and boundaries in order to avoid widely discrepant products. A variety of geologic maps were subsequently produced for various purposes, including 1:5M scale global maps [4-9] and large scale maps of high scientific interest (including the Apollo landing sites) [10]. Since that time, lunar science has benefitted from an abundance of surface information, including high resolution images and diverse compositional data sets, which have yielded a host of topical planetary investigations. The existing suite of lunar geologic maps and topical studies provide exceptional context in which to unravel the geologic history of the Moon. However, there has been no systematic approach to lunar geologic mapping since the flight of post-Apollo scientific orbiters. Geologic maps provide a spatial and temporal framework wherein observations can be reliably benchmarked and compared. As such, a lack of a systematic mapping program means that modern (post- Apollo) data sets, their scientific ramifications, and the lunar scientists who investigate these data, are all marginalized in regard to geologic mapping. Marginalization weakens the overall understanding of the geologic evolution of the Moon and unnecessarily partitions lunar research. To bridge these deficiencies, we began a pilot geologic mapping project in 2005 as a means to assess the interest, relevance, and technical methods required for a renewed lunar geologic mapping program [11]. Herein, we provide a summary of the pilot geologic mapping project, which focused on the geologic materials and stratigraphic relationships within the Copernicus quadrangle (0-30degN, 0-45degW).

Mesozoic to Cenozoic magmatic history of the Pamir

Science.gov (United States)

Chapman, James B.; Scoggin, Shane H.; Kapp, Paul; Carrapa, Barbara; Ducea, Mihai N.; Worthington, James; Oimahmadov, Ilhomjon; Gadoev, Mustafo

2018-01-01

New geochronologic, geochemical, and isotopic data for Mesozoic to Cenozoic igneous rocks and detrital minerals from the Pamir Mountains help to distinguish major regional magmatic episodes and constrain the tectonic evolution of the Pamir orogenic system. After final accretion of the Central and South Pamir terranes during the Late Triassic to Early Jurassic, the Pamir was largely amagmatic until the emplacement of the intermediate (SiO2 > 60 wt.%), calc-alkaline, and isotopically evolved (-13 to -5 zircon εHf(t)) South Pamir batholith between 120-100 Ma, which is the most volumetrically significant magmatic complex in the Pamir and includes a high flux magmatic event at ∼105 Ma. The South Pamir batholith is interpreted as the northern (inboard) equivalent of the Cretaceous Karakoram batholith and the along-strike equivalent of an Early Cretaceous magmatic belt in the northern Lhasa terrane in Tibet. The northern Lhasa terrane is characterized by a similar high-flux event at ∼110 Ma. Migration of continental arc magmatism into the South Pamir terrane during the mid-Cretaceous is interpreted to reflect northward directed, low-angle to flat-slab subduction of the Neo-Tethyan oceanic lithosphere. Late Cretaceous magmatism (80-70 Ma) in the Pamir is scarce, but concentrated in the Central and northern South Pamir terranes where it is comparatively more mafic (SiO2 roll-back of the Neotethyan oceanic slab, which is consistent with similarly aged extension-related magmatism in the Karakoram terrane and Kohistan. There is an additional pulse of magmatism in the Pamir at 42-36 Ma that is geographically restricted (∼150 km diameter ellipsoidal area) and referred to as the Vanj magmatic complex. The Vanj complex comprises metaluminous, high-K calc-alkaline to shoshonitic monzonite, syenite, and granite that is adakitic (La/YbN = 13 to 57) with low Mg# (35-41). The Vanj complex displays a range of SiO2 (54-75 wt.%) and isotopic compositions (-7 to -3 εNd(i), 0.706 to

Characteristics of mesozoic magmatic rocks in western Zhejiang and their relation with uranium mineralization

International Nuclear Information System (INIS)

Zhou Jiazhi

2000-01-01

The author summarizes characteristics of Mesozoic (Yangshanian Period) acid-intermediate volcanics, sub-volcanics and basic intrusive from aspects of formation time of rock series, petrogenic sequence, chemical composition, rock -controlling factors and petrogenic environments. It is suggested that these rocks were originated from different source areas of crust and mantle. Based on the time-space relation between different types uranium deposits and magmatic rocks, the author proposes that: the earlier stage (Earlier Cretaceous) U-hematite ores were originated from acid volcanic magmatism of crustal source, but the later stage (Late Cretaceous) pitchblende-polymetallic sulfide and pitchblende-purple fluorite rich ores were derived from basic magmatism of mantle source. Finally, the author proposes prospecting criteria of the above two types of uranium deposits

Melting of subducted continental crust: Geochemical evidence from Mesozoic granitoids in the Dabie-Sulu orogenic belt, east-central China

Science.gov (United States)

Zhao, Zi-Fu; Liu, Zhi-Bin; Chen, Qi

2017-09-01

Syn-collisional and postcollisional granitoids are common in collisional orogens, and they were primarily produced by partial melting of subducted continental crust. This is exemplified by Mesozoic granitoids from the Dabie-Sulu orogenic belt in east-central China. These granitoids were emplaced in small volumes in the Late Triassic (200-206 Ma) and the Late Jurassic (146-167 Ma) but massively in the Early Cretaceous (111-143 Ma). Nevertheless, all of them exhibit arc-like trace element distribution patterns and are enriched in Sr-Nd-Hf isotope compositions, indicating their origination from the ancient continental crust. They commonly contain relict zircons with Neoproterozoic and Triassic U-Pb ages, respectively, consistent with the protolith and metamorphic ages for ultrahigh-pressure (UHP) metaigneous rocks in the Dabie-Sulu orogenic belt. Some granitoids show low zircon δ18O values, and SIMS in-situ O isotope analysis reveals that the relict zircons with Neoproterozoic and Triassic U-Pb ages also commonly exhibit low δ18O values. Neoproterozoic U-Pb ages and low δ18O values are the two diagnostic features that distinguish the subducted South China Block from the obducted North China Block. Thus, the magma source of these Mesozoic granitoids has a genetic link to the subducted continental crust of the South China Block. On the other hand, these granitoids contain relict zircons with Paleoproterozoic and Archean U-Pb ages, which are present in both the South and North China Blocks. Taken together, the Mesozoic granitoids in the Dabie-Sulu orogenic belt and its hanging wall have their magma sources that are predominated by the continental crust of the South China Block with minor contributions from the continental crust of the North China Block. The Triassic continental collision between the South and North China Blocks brought the continental crust into the thickened orogen, where they underwent the three episodes of partial melting in the Late Triassic, Late

Geology and assessment of undiscovered oil and gas resources of the Jan Mayen Microcontinent Province, 2008

Science.gov (United States)

Moore, Thomas E.; Pitman, Janet K.; Moore, Thomas E.; Gautier, D.L.

2018-01-26

The Jan Mayen Microcontinent encompasses a rectangular, mostly submarine fragment of continental crust that lies north of Iceland in the middle of the North Atlantic Ocean. These continental rocks were rifted away from the eastern margin of Greenland as a consequence of a westward jump of spreading centers from the now-extinct Aegir Ridge to the currently active Kolbeinsey Ridge in the Oligocene and early Miocene. The microcontinent is composed of the high-standing Jan Mayen Ridge and a series of smaller ridges that diminish southward in elevation and includes several deep basins that are underlain by strongly attenuated continental crust. The geology of this area is known principally from a loose collection of seismic reflection and refraction lines and several deep-sea scientific drill cores.The Jan Mayen Microcontinent petroleum province encompasses the entire area of the microcontinent and was defined as a single assessment unit (AU). Although its geology is poorly known, the microcontinent is thought to consist of late Paleozoic and Mesozoic rift basin stratigraphic sequences similar to those of the highly prospective Norwegian, North Sea, and Greenland continental margins. The prospectivity of the AU may be greatly diminished, however, by pervasive extensional deformation, basaltic magmatism, and exhumation that accompanied two periods of continental rifting and breakup in the Paleogene and early Neogene. The overall probability of at least one petroleum accumulation of >50 million barrels of oil equivalent was judged to be 5.6 percent. As a consequence of the low level of probability, a quantitative assessment of this AU was not conducted.

Molecular development of fibular reduction in birds and its evolution from dinosaurs.

Science.gov (United States)

Botelho, João Francisco; Smith-Paredes, Daniel; Soto-Acuña, Sergio; O'Connor, Jingmai; Palma, Verónica; Vargas, Alexander O

2016-03-01

Birds have a distally reduced, splinter-like fibula that is shorter than the tibia. In embryonic development, both skeletal elements start out with similar lengths. We examined molecular markers of cartilage differentiation in chicken embryos. We found that the distal end of the fibula expresses Indian hedgehog (IHH), undergoing terminal cartilage differentiation, and almost no Parathyroid-related protein (PTHrP), which is required to develop a proliferative growth plate (epiphysis). Reduction of the distal fibula may be influenced earlier by its close contact with the nearby fibulare, which strongly expresses PTHrP. The epiphysis-like fibulare however then separates from the fibula, which fails to maintain a distal growth plate, and fibular reduction ensues. Experimental downregulation of IHH signaling at a postmorphogenetic stage led to a tibia and fibula of equal length: The fibula is longer than in controls and fused to the fibulare, whereas the tibia is shorter and bent. We propose that the presence of a distal fibular epiphysis may constrain greater growth in the tibia. Accordingly, many Mesozoic birds show a fibula that has lost its distal epiphysis, but remains almost as long as the tibia, suggesting that loss of the fibulare preceded and allowed subsequent evolution of great fibulo-tibial disparity. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Ecosystem evolution of Lake Gusinoe (Transbaikal region, Russia)

Energy Technology Data Exchange (ETDEWEB)

Pisarsky, B.L.; Hardina, A.M.; Naganawa, H. [Russian Academy of Science, Irkutsk (Russian Federation). Siberian Division

2005-12-01

Lake Gusinoe is situated on a basin originating from Paleozoic and Mesozoic deposits. The recorded history of the lake's ecosystem evolution is no more than 300 years. The present lake drainage basin was formed mainly in the Cenozoic era, but during the past century, major anthropogenic impacts on the lake have occurred. The human-influenced evolution of the ecosystem began in the 1940s with the development of opencut coal mining nearby the lake. Population increase and the building of the Gusinoozersk State Regional Power Plant, the TransMongolian Railroad and an associated station, and military installations were the major sources of anthropogenic impacts. Since the early 1950s about five species of fish have been introduced into Lake Gusinoe or have invaded the lake, and at least six of the native species have disappeared or are in danger of extinction. From our recent investigations, the present environment of the Lake Gusinoe Basin (Gusinoozersk Basin) is divided into four zones hydro-geochemically: (1) ultrafreshwater, (2) freshwater, (3) mineralized water, and (4) hyposaline and saltwater. Some additional data on changes of the chemical components of the drainage basin waters, as well as on the transition of zooplankton and zoobenthic fauna, are presented in consideration of the risk of industrial development, and the perspectives are discussed.

Triassic Sequence Geological Development of the Arctic with focus on Svalbard and the Barents Shelf

Energy Technology Data Exchange (ETDEWEB)

Moerk, Atle

1998-12-31

Triassic rocks are of great interest for exploration in Arctic areas as they have proved to include both good hydrocarbon source rocks and potential hydrogen reservoir rocks. In this thesis, the stratigraphy and sedimentology of the Arctic Triassic successions are studied within a sequence stratigraphical framework. Inter-regional comparisons throughout the Arctic are based on comparisons of transgressive-regressive sequences. Improved dating of the studied sequences, and the recognition and correlation of sequence boundaries of second and third order, facilitate interpretation of facies distribution and the geological development both within and between the studied areas. Main emphasis is given to the Triassic succession of Svalbard and the Barents Shelf, which through this study is integrated within a circum-Arctic sequence stratigraphical framework. Good correspondence of the Triassic sequence boundaries between the different Arctic areas indicate that they are mainly controlled by eustacy, while decreasing correspondence of the sequence boundaries in the Jurassic and Cretaceous periods indicate that local and large scale tectonism becomes progressively more dominant in the circum-Arctic Realm through the Mesozoic Era. These hypotheses are further discussed. 701 refs., 110 figs., 12 tabs.

Diffusion Dominant Solute Transport Modelling in Fractured Media Under Deep Geological Environment - 12211

Energy Technology Data Exchange (ETDEWEB)

Kwong, S. [National Nuclear Laboratory (United Kingdom); Jivkov, A.P. [Research Centre for Radwaste and Decommissioning and Modelling and Simulation Centre, University of Manchester (United Kingdom)

2012-07-01

Deep geologic disposal of high activity and long-lived radioactive waste is gaining increasing support in many countries, where suitable low permeability geological formation in combination with engineered barriers are used to provide long term waste contaminant and minimise the impacts to the environment and risk to the biosphere. This modelling study examines the solute transport in fractured media under low flow velocities that are relevant to a deep geological environment. In particular, reactive solute transport through fractured media is studied using a 2-D model, that considers advection and diffusion, to explore the coupled effects of kinetic and equilibrium chemical processes. The effects of water velocity in the fracture, matrix porosity and diffusion on solute transport are investigated and discussed. Some illustrative modelled results are presented to demonstrate the use of the model to examine the effects of media degradation on solute transport, under the influences of hydrogeological (diffusion dominant) and microbially mediated chemical processes. The challenges facing the prediction of long term degradation such as cracks evolution, interaction and coalescence are highlighted. The potential of a novel microstructure informed modelling approach to account for these effects is discussed, particularly with respect to investigating multiple phenomena impact on material performance. The GRM code is used to examine the effects of media degradation for a geological waste disposal package, under the combined hydrogeological (diffusion dominant) and chemical effects in low groundwater flow conditions that are typical of deep geological disposal systems. An illustrative reactive transport modelling application demonstrates the use of the code to examine the interplay of kinetic controlled biogeochemical reactive processes with advective and diffusive transport, under the influence of media degradation. The initial model results are encouraging which show the

Paleomagnetic Constraints on the Tectonic History of the Mesozoic Ophiolite and Arc Terranes of Western Mexico

Science.gov (United States)

Boschman, L.; Van Hinsbergen, D. J. J.; Langereis, C. G.; Molina-Garza, R. S.; Kimbrough, D. L.

2017-12-01

The North American Cordillera has been shaped by a long history of accretion of arcs and other buoyant crustal fragments to the western margin of the North American Plate since the Early Mesozoic. Accretion of these terranes resulted from a complex tectonic history interpreted to include episodes of both intra-oceanic subduction within the Panthalassa/Pacific Ocean, as well as continental margin subduction along the western margin of North America. Western Mexico, at the southern end of the Cordillera, contains a Late Cretaceous-present day long-lived continental margin arc, as well as Mesozoic arc and SSZ ophiolite assemblages of which the origin is under debate. Interpretations of the origin of these subduction-related rock assemblages vary from far-travelled exotic intra-oceanic island arc character to autochthonous or parautochthonous extended continental margin origin. We present new paleomagnetic data from four localities: (1) the Norian SSZ Vizcaíno peninsula Ophiolite; (2) its Lower Jurassic sedimentary cover; and (3) Barremian and (4) Aptian sediments derived from the Guerrero arc. The data show that the Mexican ophiolite and arc terranes have a paleolatitudinal plate motion history that is equal to that of the North American continent. This suggests that these rock assemblages were part of the overriding plate and were perhaps only separated from the North American continent by temporal fore- or back-arc spreading. These spreading phases resulted in the temporal existence of tectonic plates between the North American and Farallon Plates, and upon closure of the basins, in the growth of the North American continent without addition of any far-travelled exotic terranes.

Geology of the Prince William Sound and Kenai Peninsula region, Alaska

Science.gov (United States)

Wilson, Frederic H.; Hults, Chad P.

2012-01-01

The Prince William Sound and Kenai Peninsula region includes a significant part of one of the world’s largest accretionary complexes and a small part of the classic magmatic arc geology of the Alaska Peninsula. Physiographically, the map area ranges from the high glaciated mountains of the Alaska and Aleutian Ranges and the Chugach Mountains to the coastal lowlands of Cook Inlet and the Copper River delta. Structurally, the map area is cut by a number of major faults and postulated faults, the most important of which are the Border Ranges, Contact, and Bruin Bay Fault systems. The rocks of the map area belong to the Southern Margin composite terrane, a Tertiary and Cretaceous or older subduction-related accretionary complex, and the Alaska Peninsula terrane. Mesozoic rocks between these two terranes have been variously assigned to the Peninsular or the Hidden terranes. The oldest rocks in the map area are blocks of Paleozoic age within the mélange of the McHugh Complex; however, the protolith age of the greenschist and blueschist within the Border Ranges Fault zone is not known. Extensive glacial deposits mantle the Kenai Peninsula and the lowlands on the west side of Cook Inlet and are locally found elsewhere in the map area. This map was compiled from existing mapping, without generalization, and new or revised data was added where available.

Mesozoic and Cenozoic tectonics of the eastern and central Alaska Range: Progressive basin development and deformation in a suture zone

Science.gov (United States)

Ridgway, K.D.; Trop, J.M.; Nokleberg, W.J.; Davidson, C.M.; Eastham, K.R.

2002-01-01

Analysis of late Mesozoic and Cenozoic sedimentary basins, metamorphic rocks, and major faults in the eastern and central Alaska Range documents the progressive development of a suture zone that formed as a result of collision of an island-arc assemblage (the Wrangellia composite terrane) with the former North American continental margin. New basin-analysis, structural, and geochronologic data indicate the following stages in the development of the suture zone: (1) Deposition of 3-5 km of Upper Jurassic-Upper Cretaceous marine strata (the Kahiltna assemblage) recorded the initial collision of the island-arc assemblage with the continental margin. The Kahiltna assemblage exposed in the northern Talkeetna Mountains represents a Kimmeridgian-Valanginian backarc basin that was filled by northwestward-flowing submarine-fan systems that were transporting sediment derived from Mesozoic strata of the island-arc assemblage. The Kahiltna assemblage exposed in the southern Alaska Range represents a Valanginian-Cenomanian remnant ocean basin filled by west-southwestward-flowing submarine-fan systems that were transporting sediment derived from Paleozoic continental-margin strata uplifted in the along-strike suture zone. A belt of retrograde metamorphism and a regional anticlinorium developed along the continental margin from 115 to 106 Ma, roughly coeval with the end of widespread deposition in the Kahiltna sedimentary basins. (2) Metamorphism of submarine-fan deposits of the Kahiltna basin, located near the leading edge of the island-arc assemblage, occurred at ca. 74 Ma, as determined from a new U-Pb zircon age for a synkinematic sill. Coeval with metamorphism of deposits of the Kahiltna basin in the southern part of the suture zone was development of a thrust-top basin, the Cantwell basin, in the northern part of the suture zone. Geologic mapping and compositional data suggest that the 4 km of Upper Cretaceous nonmarine and marginal marine sedimentary strata in this basin

Sedimentary Basins of the Republic of Yemen : Their Structural Evolution and Geological Characteristics Evolution structurelle et caractéristiques géologiques des bassins sédimentaires de la république du Yemen

Directory of Open Access Journals (Sweden)

Beydoun Z. R.

2006-11-01

Full Text Available The distribution and evolution of the sedimentary basins of Yemen was, until recently, poorly understood as this was based entirely on surface geology and correlations of the older stratigraphic units which were exposed only in the deeply dissected bordering uplifts of the Gulf of Aden and Red Sea or the high plateau of the north west. Elsewhere cover by the tabular Tertiary sedimentary blanket and the Tertiary Volcanic Group lavas masked the major underlying pre-Cenozoic structural elements and sedimentary successions. Earlier attempts at the delineation of the country's structural framework were, thus, sketchy and/or only partially correct. The discovery of commercial oil and gas in several interior Mesozoic rift basins of Yemen in the late 1980s and in the early 1990s after unification of the former two Yemens, spured many oil companies to enter the exploration race and carry out detailed seismic surveys and intensive exploration drilling in many areas. This resulted in a rapid rise in overall new subsurface geological data acquisition and an increasingly clearer perception of the distribution, orientation and inception times of the main basins. No overall synthesis of results was, however, undertaken since each individual company was primarily concerned with its own concession area and its immediate surroundings. Recent studies involving the review, correlation and synthesis of the mass of new subsurface stratigraphic data in connection with standardisation of lithostratigraphic nomenclature in use in Yemen and its further formalisation in accordance with internationally accepted rules, have, perforce, required the establishment of an overall structural framework within which inter and intra-basinal stratigraphic correlation could be carried out. It is this new framework of depositional basins and interbasinal uplifts that is discussed here. The main Mesozoic basins are related to late Jurassic extension and rifting, principally involving

The geological attitude

International Nuclear Information System (INIS)

Fuller, J.G.C.M.

1992-01-01

This paper discusses geological activity which takes place mainly in response to industrial and social pressures. Past geological reaction to these pressures profoundly altered popular conceptions of time, the Church, man, and the balance of nature. The present-day circumstances of geology are not essentially different from those of the past. Petroleum geology in North American illustrates the role of technology in determining the style and scope of geological work. Peaks of activity cluster obviously on the introduction from time to time of new instrumental capabilities (geophysical apparatus, for example), although not infrequently such activity is testing concepts or relationships perceived long before. Organic metamorphism and continental drift provide two examples. The petroleum industry now faces the dilemma of satisfying predicted demands for fuel, without doing irreparable injury to its environment of operation. Awareness of man's place in nature, which is a fundamental perception of geology, governs the geological attitude

Phases of metamorphism in the metamorphic base of Xiangshan uranium orefield

International Nuclear Information System (INIS)

Jiang Zhenpin; Dong Yongjie; Hu Rongquan; Wu Shuilin

2008-01-01

Metamorphic rocks in the basement of Xiangshan uranium orefield, experienced long-term complex metamorphic-deformational evolution. From Jinning period to later Mesozoic era. It had suffered from four phase of superimposed metamorphism: regional dynamo thermal metamorphism in Mesoproterozoic era, contact-thermal metamorphism after mesoproterozoic era, dynamic metamorphism in Mesozoic era and contact-thermal metamorphism in the later of Mesozoic era. Multi-phase superimposed metamorphism show that Xiangshan area is a geothermally anomalous area ever since Proterozoic Eon. In Xiangshan area, the uranium mineralization are the outcome of superimposition of tectonism-magmatism-metamorphism. (authors)

Quantitative geological modeling based on probabilistic integration of geological and geophysical data

DEFF Research Database (Denmark)

Gulbrandsen, Mats Lundh

In order to obtain an adequate geological model of any kind, proper integration of geophysical data, borehole logs and geological expert knowledge is important. Geophysical data provide indirect information about geology, borehole logs provide sparse point wise direct information about geology...... entitled Smart Interpretation is developed. This semi-automatic method learns the relation between a set of data attributes extracted from deterministically inverted airborne electromagnetic data and a set of interpretations of a geological layer that is manually picked by a geological expert...

Geological structure and mineral resources of Algeria

Directory of Open Access Journals (Sweden)

Eduard Dobra

2007-12-01

Full Text Available The hydrocarbon System Ourd Mya is located in the Sahara Basin. It is one of the producing basins in Algeria. The stratigraphic section consists of Paleozoic and Mesosoic, it is about 5000 m thick. In the eastern part, the basin is limited by the Hassi-Messaoud high zone which is a giant oil field produced from the Cambrian sands. The western part is limited by Hassi R`mel which is one of the biggest gas field in the world, it is produced from the triassic sands. The Mesozoic section lays on the lower Devonian and in the eastern part, on the Cambrian. The main source rock is Silurian shale with an average thickness of 50 m and a total organic matter of 6 % (14 % in some cases. Results of maturation modeling indicate that the lower Silurian source is in the oil window. The Ordovician shales are also a source rock but in a second order. Clastic reservoirs are in the Triassic sequence which is mainly fluvial deposit with complex alluvial channels, it is the main target in the basin. Clastic reservoirs within the lower Devonian section have a good hydrocarbon potential in the east of the basin through a southwest-northeast orientation. The late Triassic-Early Jurassic evaporites overlie the Triassic clastic interval and extend over the entire Oued Mya Basin. This is considered as a super-seal evaporate package, which consists predominantly of anhydrite and halite. For Paleozoic targets, a large number of potential seals exist within the stratigraphic column.This paper describe the main geological structure and mineral resources of Algeria.

Structure and geological evolution of the bedrock at southern Satakunta, SW Finland

Energy Technology Data Exchange (ETDEWEB)

Paulamaeki, S.; Paananen, M.; Elo, S. [Geological Survey of Finland (Finland)

2002-02-01

The southern Satakunta area lies on the west coast of Finland, mainly covering the mainland (with main towns Pori and Rauma), but also including the coastal archipelago and part of the Bothnian Sea. Near the centre of the area lies the island of Olkiluoto, on which Finland's site for a deep repository for spent nuclear fuel is located. The purpose of the present report is to compile and interpret all available geological and geophysical data relevant to understanding the regional geological setting of the Olkiluoto site. The area described is covered by four 1:100 000 scale geological map sheets, published by the Geological Survey of Finland, which, together with low-altitude aeromagnetic maps, provide the basis for a new 1:250 000 geological map compilation. This shows that the bedrock of southern Satakunta can be subdivided into three main zones: a pelitic migmatite belt in the southwest, a central, NW-SE trending area of sandstone, and a psammitic migmatite belt in the northeast. The migmatite belts formed during the Svecofennian orogeny, 1900-1800 Ma ago (Palaeoproterozoic). The sandstone area is the remnant of an alluvial basin, preserved now in a NW-SE trending graben, bounded on both sides by normal fault zones. The sandstones are thought to be at least 1400-1300 Ma old (Mesoproterozoic), and they are cut by Postjotnian olivine diabase dykes, 1270-1250 Ma in age. The Svecofennian migmatite belts show a complex history of formation, with various phases of anatexis/metamorphism, deformation and intrusion. In the pelitic migmatite belt, in which the Olkiluoto site is situated, four phases of ductile deformation (D-D4) and two phases of regional highT/lowP metamorphism and migmatite formation can be recognised, together with synorogenic (tonalite, granodiotite) and late orogenic ( potassium granite) intrusions. Subsequently, this very heterogeneous complex was intruded by anorogenic rapakivi granites, with ages 1580-1550 Ma. One pluton, the Eurajoki stock

Terrestrial analogs, planetary geology, and the nature of geological reasoning

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Baker, Victor R.

2014-05-01

Analogical reasoning is critical to planetary geology, but its role can be misconstrued by those unfamiliar with the practice of that science. The methodological importance of analogy to geology lies in the formulation of genetic hypotheses, an absolutely essential component of geological reasoning that was either ignored or denigrated by most 20th century philosophers of science, who took the theoretical/ experimental methodology of physics to be the sole model for all of scientific inquiry. Following the seminal 19th century work of Grove Karl Gilbert, an early pioneer of planetary geology, it has long been recognized that broad experience with and understanding of terrestrial geological phenomena provide geologists with their most effective resource for the invention of potentially fruitful, working hypotheses. The actions of (1) forming such hypotheses, (2) following their consequences, and (3) testing those consequences comprise integral parts of effective geological practice in regard to the understanding of planetary surfaces. Nevertheless, the logical terminology and philosophical bases for such practice will be unfamiliar to most planetary scientists, both geologists and nongeologists. The invention of geological hypotheses involves both inductive inferences of the type Gilbert termed “empiric classification” and abductive inferences of a logical form made famous by the 19th century American logician Charles Sanders Peirce. The testing and corroboration of geological hypotheses relies less on the correspondence logic of theoretical/ experimental sciences, like physics, and more on the logic of consistency, coherence, and consilience that characterizes the investigative and historical sciences of interpretation exemplified by geology.

Health benefits of geologic materials and geologic processes

Science.gov (United States)

Finkelman, R.B.

2006-01-01

The reemerging field of Medical Geology is concerned with the impacts of geologic materials and geologic processes on animal and human health. Most medical geology research has been focused on health problems caused by excess or deficiency of trace elements, exposure to ambient dust, and on other geologically related health problems or health problems for which geoscience tools, techniques, or databases could be applied. Little, if any, attention has been focused on the beneficial health effects of rocks, minerals, and geologic processes. These beneficial effects may have been recognized as long as two million years ago and include emotional, mental, and physical health benefits. Some of the earliest known medicines were derived from rocks and minerals. For thousands of years various clays have been used as an antidote for poisons. "Terra sigillata," still in use today, may have been the first patented medicine. Many trace elements, rocks, and minerals are used today in a wide variety of pharmaceuticals and health care products. There is also a segment of society that believes in the curative and preventative properties of crystals (talismans and amulets). Metals and trace elements are being used in some of today's most sophisticated medical applications. Other recent examples of beneficial effects of geologic materials and processes include epidemiological studies in Japan that have identified a wide range of health problems (such as muscle and joint pain, hemorrhoids, burns, gout, etc.) that may be treated by one or more of nine chemically distinct types of hot springs, and a study in China indicating that residential coal combustion may be mobilizing sufficient iodine to prevent iodine deficiency disease. ?? 2006 MDPI. All rights reserved.

UT-CT: A National Resource for Applications of High-Resolution X-ray Computed Tomography in the Geological Sciences

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Carlson, W. D.; Ketcham, R. A.; Rowe, T. B.

2002-12-01

modeling of melt extraction during anatexis, and visualizing and quantifying the deformation of continuous 3-D plagioclase-chain networks in slowly cooled basalt flows to evaluate differentiation by compaction of a crystal mush. Meteoritical research includes measuring sizes of chondrules and metal-troilite particles in chondritic meteorites to test hypotheses of sorting during condensation of the solar nebula; visualizing paths of migration for molten metal in rare lodranite meteorites to gain insight into processes of core segregation in terrestrial planets; measurement of vesicles and voids in basaltic meteorites to examine flow rates and mechanisms; and imaging of metal/clast relationships in a brecciated chondrite to demonstrate impact-induced metamorphism, metal fusion, and brecciation on the meteorite's parent body. Paleontological studies include analysis of fossil jaws of Mesozoic marsupials to establish the antiquity of distinctive patterns of tooth replacement and reproductive strategies seen in modern marsupials; comparisons of the internal cranial anatomy of mammals and their closest extinct relatives to pinpoint the evolutionary origin of the mammalian neocortex, the locus of advanced sensory perception and integration; and description of the evolution of the avian brain and braincase from those of non-avian dinosaurs, from CT data on skulls of the oldest known dinosaurs and complete skeletal analysis of the world's second oldest bird.

Key scientific challenges in geological disposal of high level radioactive waste

International Nuclear Information System (INIS)

Wang Ju

2007-01-01

The geological disposal of high radioactive waste is a challenging task facing the scientific and technical world. This paper introduces the latest progress of high level radioactive disposal programs in the latest progress of high level radioactive disposal programs in the world, and discusses the following key scientific challenges: (1) precise prediction of the evolution of a repository site; (2) characteristics of deep geological environment; (3) behaviour of deep rock mass, groundwater and engineering material under coupled con-ditions (intermediate to high temperature, geostress, hydraulic, chemical, biological and radiation process, etc); (4) geo-chemical behaviour of transuranic radionuclides with low concentration and its migration with groundwater; and (5) safety assessment of disposal system. Several large-scale research projects and several hot topics related with high-level waste disposal are also introduced. (authors)

Applications of Micro-Fourier Transform Infrared Spectroscopy (FTIR) in the Geological Sciences—A Review

Science.gov (United States)

Chen, Yanyan; Zou, Caineng; Mastalerz, Maria; Hu, Suyun; Gasaway, Carley; Tao, Xiaowan

2015-01-01

Fourier transform infrared spectroscopy (FTIR) can provide crucial information on the molecular structure of organic and inorganic components and has been used extensively for chemical characterization of geological samples in the past few decades. In this paper, recent applications of FTIR in the geological sciences are reviewed. Particularly, its use in the characterization of geochemistry and thermal maturation of organic matter in coal and shale is addressed. These investigations demonstrate that the employment of high-resolution micro-FTIR imaging enables visualization and mapping of the distributions of organic matter and minerals on a micrometer scale in geological samples, and promotes an advanced understanding of heterogeneity of organic rich coal and shale. Additionally, micro-FTIR is particularly suitable for in situ, non-destructive characterization of minute microfossils, small fluid and melt inclusions within crystals, and volatiles in glasses and minerals. This technique can also assist in the chemotaxonomic classification of macrofossils such as plant fossils. These features, barely accessible with other analytical techniques, may provide fundamental information on paleoclimate, depositional environment, and the evolution of geological (e.g., volcanic and magmatic) systems. PMID:26694380

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2004-02-25

The University of Alabama, in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company, has undertaken an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary goal of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. Geoscientific reservoir property, geophysical seismic attribute, petrophysical property, and engineering property characterization has shown that reef (thrombolite) and shoal reservoir lithofacies developed on the flanks of high-relief crystalline basement paleohighs (Vocation Field example) and on the crest and flanks of low-relief crystalline basement paleohighs (Appleton Field example). The reef thrombolite lithofacies have higher reservoir quality than the shoal lithofacies due to overall higher permeabilities and greater interconnectivity. Thrombolite dolostone flow units, which are dominated by dolomite intercrystalline and vuggy pores, are characterized by a pore system comprised of a higher percentage of large-sized pores and larger pore throats. Rock-fluid interactions (diagenesis) studies have shown that although the primary control on

Geology and assessment of undiscovered oil and gas resources of the West Greenland-East Canada Province, 2008

Science.gov (United States)

Schenk, Christopher J.; Moore, Thomas E.; Gautier, Donald L.

2018-01-05

The U.S. Geological Survey (USGS) recently assessed the potential for undiscovered oil and gas resources of the West Greenland-East Canada Province as part of the USGS Circum-Arctic Resource Appraisal program. The province lies in the offshore area between western Greenland and eastern Canada and includes Baffin Bay, Davis Strait, Lancaster Sound, and Nares Strait west of, and including, part of Kane Basin. A series of major tectonic events led to the formation of several distinct structural domains that are the geologic basis for defining five assessment units (AU ) in the province, all of which are within the Mesozoic-Cenozoic Composite Total Petroleum System (TPS). Potential petroleum source rocks within the TPS include strata of Ordovician, Lower and Upper Cretaceous, and Paleogene ages. The five AUs defined for this study—the Eurekan Structures AU, Northwest Greenland Rifted Margin AU, Northeast Canada Rifted Margin AU, Baffin Bay Basin AU, and the Greater Ungava Fault Zone AU— encompass the entire province and were assessed for undiscovered, technically recoverable resources. The estimated mean volumes of undiscovered resources for the West GreenlandEast Canada Province are 10.7 billion barrels of oil, 75 trillion cubic feet of gas, and 1.7 billion barrels of natural gas liquids. For the part of the province that is north of the Arctic Circle, the estimated mean volumes of these undiscovered resources are 7.3 billion barrels of oil, 52 trillion cubic feet of natural gas, and 1.1 billion barrels of natural-gas liquids.

Phylogenic insights into the enucleation of erythroblasts in human.

Science.gov (United States)

Nunomura, Wataru

2016-07-01

Two key questions remain unanswered in the erythropoiesis field: Why and how do erythroblasts enucleate in mammalian species? Recent studies have unveiled the roles of various molecules, cytoskeletal proteins, motor proteins, vesicle transport, signaling pathways, lipid rafts and actomyosin ring contraction in the enucleation process. However, few reports provide insights into the fitness benefit for mammalian species of having anucleate erythrocytes. Herein, we discuss the biological significance of enucleation of human erythroblasts based on our recent results and on evolutionary considerations related to the biology of hemoglobin and the comparative biochemistry of erythrocyte membrane cytoskeletal proteins, such as protein 4.1R. We specifically focus on the Mesozoic era, a geological period during which dinosaurs and the ancestors of mammalian species coexisted. Approximately 200 million years ago, at the beginning of this era, the earth's atmosphere was hypoxic. Interestingly, animals adopted different respiration systems to adapt to this hypoxic environment. Recent studies using state-of-the-art technologies have shown that dinosaurs might have had nucleated erythrocytes. After dinosaurs became extinct about 65.5 million years ago, their respiration system was maintained by birds. We propose a new adaptive theory that establishes a correlation between evolution towards nucleated or anucleate erythrocytes depending on organism respiration systems during the Mesozoic era.

Geologic drivers of late ordovician faunal change in laurentia: investigating links between tectonics, speciation, and biotic invasions.

Directory of Open Access Journals (Sweden)

David F Wright

Full Text Available Geologic process, including tectonics and global climate change, profoundly impact the evolution of life because they have the propensity to facilitate episodes of biogeographic differentiation and influence patterns of speciation. We investigate causal links between a dramatic faunal turnover and two dominant geologic processes operating within Laurentia during the Late Ordovician: the Taconian Orogeny and GICE related global cooling. We utilize a novel approach for elucidating the relationship between biotic and geologic changes using a time-stratigraphic, species-level evolutionary framework for articulated brachiopods from North America. Phylogenetic biogeographic analyses indicate a fundamental shift in speciation mode-from a vicariance to dispersal dominated macroevolutionary regime-across the boundary between the Sandbian to Katian Stages. This boundary also corresponds to the onset of renewed intensification of tectonic activity and mountain building, the development of an upwelling zone that introduced cool, nutrient-rich waters into the epieric seas of eastern Laurentia, and the GICE isotopic excursion. The synchronicity of these dramatic geologic, oceanographic, and macroevolutionary changes supports the influence of geologic events on biological evolution. Together, the renewed tectonic activity and oceanographic changes facilitated fundamental changes in habitat structure in eastern North America that reduced opportunities for isolation and vicariance. They also facilitated regional biotic dispersal of taxa that led to the subsequent establishment of extrabasinal (=invasive species and may have led to a suppression of speciation within Laurentian faunas. Phylogenetic biogeographic analysis further indicates that the Richmondian Invasion was a multidirectional regional invasion event that involved taxa immigrating into the Cincinnati region from basins located near the continental margins and within the continental interior.

Hydro-Geological Hazard Temporal Evolution during the last seven decades in the Solofrana River Basin—Southern Italy

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Longobardi, Antonia; Diodato, Nazzareno; Mobilia, Mirka

2017-04-01

Extremes precipitation events are frequently associated to natural disasters falling within the broad spectrum of multiple damaging hydrological events (MDHEs), defined as the simultaneously triggering of different types of phenomena, such as landslides and floods. The power of the rainfall (duration, magnitude, intensity), named storm erosivity, is an important environmental indicator of multiple damaging hydrological phenomena. At the global scale, research interest is actually devoted to the investigation of non-stationary features of extreme events, and consequently of MDHEs, which appear to be increasing in frequency and severity. The Mediterranean basin appears among the most vulnerable regions with an expected increase in occurring damages of about 100% by the end of the century. A high concentration of high magnitude and short duration rainfall events are, in fact, responsible for the largest rainfall erosivity and erosivity density values within Europe. The aim of the reported work is to investigate the relationship between the temporal evolution of severe geomorphological events and combined precipitation indices as a tool to improve understanding the hydro-geological hazard at the catchment scale. The case study is the Solofrana river basin, Southern Italy, which has been seriously and consistently in time affected by natural disasters. Data for about 45 MDH events, spanning on a decadal scale 1951-2014, have been collected and analyzed for this purpose. A preliminary monthly scale analysis of event occurrences highlights a pronounced seasonal characterization of the phenomenon, as about 60% of the total number of reported events take place during the period from September to November. Following, a statistical analysis clearly indicates a significant increase in the frequency of occurrences of MDHEs during the last decades. Such an increase appears to be related to non-stationary features of an average catchment scale rainfall-runoff erosivity index

Introduction to the special issue on the Phanerozoic geology of Egypt in honor of Professor Mohamed El-Bahay Issawi

Science.gov (United States)

Abdeen, M. M.; Tewksbury, B.; Abdelsalam, M. G.; Tarabees, E.

2017-12-01

This issue is dedicated to Professor Mohamed El-Bahay Issawi in recognition of his monumental contributions to an understanding of the Phanerozoic evolution of the northern part of Africa. During his long and productive career in the Egyptian Geological Survey and Mining Authority (EGSMA), he was committed to deciphering the geological history and resources of the Phanerozoic of Egypt. Professor Issawi is widely recognized for his influential stratigraphic-tectonic models that were an inspiration for generations of Egyptian geoscientists from the 1960s onward. His models and expertise helped to attract international interest and involvement in fundamental programs of research on the Phanerozoic geology of Egypt and specifically on geoarchaeology.

Geology and mineral occurences of braquiantidinal do Lontra - GO

International Nuclear Information System (INIS)

Macambira, J.B.

1983-01-01

This work involved the geological mapping (in the scale 1:60.000) of an area of 800 square kilometers in the nortwestern part of the state of Goias, near and east of the Araguaia river. Based on the stratigraphy, metamorphism, geochronology, magmatism and mineral deposits hypotheses on the geological evolution of the region are discussed. The area studied belongs to the Precambrian Araguaia Fold Belt. The oldest rocks identified are trondhjemitic gneisses and on these rocks was deposited a sedimentary sequence with minor volcanics of a geosynclinal type. The stratigraphic column of Abreu (1978) was adopted with minor modifications. The basement, of transamazonic age (2000 Ma), consists mostly of gneiss, migmatite, granite gneiss and amphibolite. The metasediments belongs to the lower unit (Estrondo Group) of the Supergroup Baixo Araguaia. The Estrondo Group, of brasilian age (600 Ma), consists in the area of the lowermost Morro do Campo Formation, mainly quartzite and amphibolite, which give the high relief of the brachyanticlines of Lontra and Ramal do Lontra.(author)

Model of climate evolution based on continental drift and polar wandering

Science.gov (United States)

Donn, W. L.; Shaw, D. M.

1977-01-01

The thermodynamic meteorologic model of Adem is used to trace the evolution of climate from Triassic to present time by applying it to changing geography as described by continental drift and polar wandering. Results show that the gross changes of climate in the Northern Hemisphere can be fully explained by the strong cooling in high latitudes as continents moved poleward. High-latitude mean temperatures in the Northern Hemisphere dropped below the freezing point 10 to 15 m.y. ago, thereby accounting for the late Cenozoic glacial age. Computed meridional temperature gradients for the Northern Hemisphere steepened from 20 to 40 C over the 200-m.y. period, an effect caused primarily by the high-latitude temperature decrease. The primary result of the work is that the cooling that has occurred since the warm Mesozoic period and has culminated in glaciation is explainable wholly by terrestrial processes.

Polycyclic evolution of the Quadrilatero Ferrifero: an analysis based on the actual knowledge of the U-Pb geochronology and Sm-Nd isotopic geochemistry

International Nuclear Information System (INIS)

Carneiro, Mauricio Antonio; Noce, Carlos Mauricio; Teixeira, Wilson

1995-01-01

The tectonic evolution of the Quadrilatero Ferrifero region, based on geochronological U-Pb, Pb-Pb, Sm-Nd, Rb-Sr e K-Ar data, is characterized by several processes of crustal growth, which began in Middle Archean. The Lower Archean geological evolution of the Quadrilatero Ferrifero was finished by the Rio de Velhas tectono-thermal event around 2,78 Ga. After this, during the proterozoic era, three tectono-sedimentary cycles took place on this Lower Archean crustal fragment, whose products are represented by the meta sedimentary sequences of the Minas Supergroup, Itacolomi Group and Espinhaco Supergroup. The Transamazonico Event (ca. 2,0 Ga) ended the geological evolution of Minas Supergroup, but its geological records did not have the same size imprints throughout region. Many places, such as the Bonfim Metamorphic Complex, were not affected by this tectonic event. Later tectonic event. Later tectonic events (e.g. Brasiliano) had even more discrete geological occurred during the Proterozoic era, when many sedimentary basins developed (e.g. Espinhaco and Sao Francisco basins). (author)

Geology and religion - historical perspective and current problems

Science.gov (United States)

Kölbl-Ebert, Martina

2010-05-01

Today, when referring to the relationship between geology and religion, people usually at once think of Christian (and other) fundamentalists and their chronic palaeontological illiteracy leading to Creationism, to Intelligent Design, and a distrust of science in general among them most prominently geology, palaeontology and evolutionary biology. Thus the relationship of geology and religion is usually considered to be under strain. In former times things used to be quite different, and for most of human history the observation of geological phenomena and the acquisition of geological expertise was intimately connected with religious ideas. The Judeo-Christian sense of a finite Earth history prepared the ground for accepting the Earth's different strata as testimony to the development of our globe through time. It was this religious, theological framework, from which the early geology started to evolve. However, with increasing observations there was a growing mismatch between what was expected according to ancient, scriptural authorities and the actual data. The release of geology from religious connotations or associations was a development closely connected with the Enlightenment, when geology and religion started to drift apart not with a violent rupture but in a subtle and sometimes circuitous manner. However, outside the group of people with geological expertise, not all was smooth and peaceful, and some conservative clergymen as well as laypersons were rather shocked by the new ideas that came with geology: the immensity of the timescale, a dynamic Earth, not just a ruin shaped by the Deluge, and a dynamic biology too with the Darwinian theory of evolution, which was founded in part on palaeontological evidence and the assumption of a long geological time scale. Nevertheless and interestingly the Creationism we face today is a rather recent phenomenon influenced by a number of motives, most of them philosophical and theological in nature. And so, the current

Global plate boundary evolution and kinematics since the late Paleozoic

Science.gov (United States)

Matthews, Kara J.; Maloney, Kayla T.; Zahirovic, Sabin; Williams, Simon E.; Seton, Maria; Müller, R. Dietmar

2016-11-01

Many aspects of deep-time Earth System models, including mantle convection, paleoclimatology, paleobiogeography and the deep Earth carbon cycle, require high-resolution plate motion models that include the evolution of the mosaic of plate boundaries through time. We present the first continuous late Paleozoic to present-day global plate model with evolving plate boundaries, building on and extending two previously published models for the late Paleozoic (410-250 Ma) and Mesozoic-Cenozoic (230-0 Ma). We ensure continuity during the 250-230 Ma transition period between the two models, update the absolute reference frame of the Mesozoic-Cenozoic model and add a new Paleozoic reconstruction for the Baltica-derived Alexander Terrane, now accreted to western North America. This 410-0 Ma open access model provides a framework for deep-time whole Earth modelling and acts as a base for future extensions and refinement. We analyse the model in terms of the number of plates, predicted plate size distribution, plate and continental root mean square (RMS) speeds, plate velocities and trench migration through time. Overall model trends share many similarities to those for recent times, which we use as a first order benchmark against which to compare the model and identify targets for future model refinement. Except for during the period 260-160 Ma, the number of plates (16-46) and ratio of "large" plates (≥ 107.5 km2) to smaller plates ( 2.7-6.6) are fairly similar to present-day values (46 and 6.6, respectively), with lower values occurring during late Paleozoic assembly and growth of Pangea. This temporal pattern may also reflect difficulties in reconstructing small, now subducted oceanic plates further back in time, as well as whether a supercontinent is assembling or breaking up. During the 260-160 Ma timeframe the model reaches a minima in the number of plates, in contrast to what we would expect during initial Pangea breakup and thus highlighting the need for refinement

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Geologic map analyses: Correlation of geologic and cratering histories. Ph.D. Thesis

Science.gov (United States)

Leake, M. A.

1982-01-01

Geologic map analyses are expanded, beginning with a discussion of particular regions which may illustrate volcanic and ballistic plains emplacement on Mercury. Major attention is focused on the surface history of Mercury through discussion of the areal distribution of plains and craters and the paleogeologic maps of the first quadrant. A summary of the lunar intercrater plains formation similarly interrelates the information from the Moon's geologic and cratering histories.

Palaeomagnetism and K-Ar age of Mesozoic and Cenozoic igneous rocks from Antarctica

International Nuclear Information System (INIS)

Valencio, D.A.; Mendia, J.E.; Vilas, J.F.

1979-01-01

A new analysis of palaeomagnetic data for igneous rocks from Deception Island, 25 de Mayo Island (King George Island) and Cape Spring, are given. K-Ar age determinations indicate that most of the igneous samples from 25 de Mayo Island included in the palaeomagnetic study are of Late Mesozoic/Early Tertiary age. The significance of these palaeomagnetic-radiometric data on the hypothesis of oroclinal bending of the Antarctic Peninsula and on the apparent polar movement of Antarctica is discussed. The positions of palaeomagnetic poles for the Andean igneous complex indicate that there has not been any apparent post-Late Cretaceous/Early Tertiary oroclinal bending in the Antarctic Peninsula from 74 0 S to 62 0 S. A comparison of the positions of palaeomagnetic poles for Antarctica and Australia suggests that the direction of apparent polar movement relative to Antarctica reversed after the Miocene. (Auth.)

Post-Viking view of Martian geologic evolution

International Nuclear Information System (INIS)

Arvidson, R.E.; Goettel, K.A.; Hohenberg, C.M.

1980-01-01

The mean density, 3.393 g/cm 3 , and the estimated moment of inertia factor constrain the density distribution within Mars but do not define it uniquely. For plausible core density, core radii can range from approx. 1350 to approx. 2200 km, with the core constituting from approx. 13 to approx. 35% of the planet's mass. Possible extremes for the zero-pressure density of the Martian mantle could be as high as 3.6 g/cm 3 or as low as 3.3 g/cm 3 . The Martian mantle is probably denser than the terrestrial mantle. The dominant Martian lavas are probably mafic or ultramafic. Martian surface materials probably consist of variable proportions of mafic igneous minerals and weathering products, the latter primarily oxides and carbonates. A major geologic dichotomy exists between the complex northern plains and the ancient southern cratered terrain. The Tharsis plateau, which dominates the low-degree harmonics of the gravity field, appears to be only partially compensated; Olympus Mons appears to be completely uncompensated. Substantial stresses must be supported, either statically by a thick, rigid lithosphere, or dynamically. Mean crustal thicknesses from 23 to 40 km have been obtained from modeling of Bouguer gravity data. Lithospheric thicknesses from 25 to 50 km under volcanoes in the Tharsis and Elysium provinces to >150 km under olympus Mons have been obtained from consideration of the effects of mass loading by volcanic constructs. Many of the compressional and extensional features on Mars have orientations consistent with formation by fracturing in response to loading by the Tharsis plateau. The deficiency of small craters within cratered terrain is attributed to obliteration by volcanism. The maximum resurfacing rate due to volcanism occurred between 1.0 and 1.5 b.y. ago if a constant cratering flux is assumed and between 3.5 and 4.0 b.y. ago if the lunar cratering flux (scaled to Mars) is assumed

Geology and bedrock engineering

International Nuclear Information System (INIS)

1985-11-01

This book deals with geology of Korea which includes summary, geology in central part and southern part in Korea and characteristic of geology structure, limestone like geology property of limestone, engineered property of limestone, and design and construction case in limestone area. It also introduces engineered property of the cenozoic, clay rock and shale, geologic and engineered property of phyllite and stratum.

The three-dimensional geologic model used for the 2003 National Oil and Gas Assessment of the San Joaquin Basin Province, California: Chapter 7 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

Science.gov (United States)

Hosford Scheirer, Allegra

2013-01-01

We present a three-dimensional geologic model of the San Joaquin Basin (SJB) that may be the first compilation of subsurface data spanning the entire basin. The model volume spans 200 × 90 miles, oriented along the basin axis, and extends to ~11 miles depth, for a total of more than 1 million grid nodes. This model supported the 2003 U.S. Geological Survey assessment of future additions to reserves of oil and gas in the SJB. Data sources include well-top picks from more than 3,200 wildcat and production wells, published cross sections, regional seismic grids, and fault maps. The model consists of 15 chronostratigraphic horizons ranging from the Mesozoic crystalline basement to the topographic surface. Many of the model units are hydrocarbon reservoir rocks and three—the Cretaceous Moreno Formation, the Eocene Kreyenhagen Formation, and the Miocene Monterey Formation—are hydrocarbon source rocks. The White Wolf Fault near the southern end of the basin divides the map volume into 2 separate fault blocks. The construction of a three-dimensional model of the entire SJB encountered many challenges, including complex and inconsistent stratigraphic nomenclature, significant facies changes across and along the basin axis, time-transgressive formation tops, uncertain correlation of outcrops with their subsurface equivalents, and contradictory formation top data. Although some areas of the model are better resolved than others, the model facilitated the 2003 resource assessment in several ways, including forming the basis of a petroleum system model and allowing a precise definition of assessment unit volumes.

The U.S. Geological Survey Geologic Collections Management System (GCMS)—A master catalog and collections management plan for U.S. Geological Survey geologic samples and sample collections

Science.gov (United States)

,

2015-01-01

The U.S. Geological Survey (USGS) is widely recognized in the earth science community as possessing extensive collections of earth materials collected by research personnel over the course of its history. In 2006, a Geologic Collections Inventory was conducted within the USGS Geology Discipline to determine the extent and nature of its sample collections, and in 2008, a working group was convened by the USGS National Geologic and Geophysical Data Preservation Program to examine ways in which these collections could be coordinated, cataloged, and made available to researchers both inside and outside the USGS. The charge to this working group was to evaluate the proposition of creating a Geologic Collections Management System (GCMS), a centralized database that would (1) identify all existing USGS geologic collections, regardless of size, (2) create a virtual link among the collections, and (3) provide a way for scientists and other researchers to obtain access to the samples and data in which they are interested. Additionally, the group was instructed to develop criteria for evaluating current collections and to establish an operating plan and set of standard practices for handling, identifying, and managing future sample collections. Policies and procedures promoted by the GCMS would be based on extant best practices established by the National Science Foundation and the Smithsonian Institution. The resulting report—USGS Circular 1410, “The U.S. Geological Survey Geologic Collections Management System (GCMS): A Master Catalog and Collections Management Plan for U.S. Geological Survey Geologic Samples and Sample Collections”—has been developed for sample repositories to be a guide to establishing common practices in the collection, retention, and disposal of geologic research materials throughout the USGS.

Respiratory evolution facilitated the origin of pterosaur flight and aerial gigantism.

Directory of Open Access Journals (Sweden)

Leon P A M Claessens

Full Text Available Pterosaurs, enigmatic extinct Mesozoic reptiles, were the first vertebrates to achieve true flapping flight. Various lines of evidence provide strong support for highly efficient wing design, control, and flight capabilities. However, little is known of the pulmonary system that powered flight in pterosaurs. We investigated the structure and function of the pterosaurian breathing apparatus through a broad scale comparative study of respiratory structure and function in living and extinct archosaurs, using computer-assisted tomographic (CT scanning of pterosaur and bird skeletal remains, cineradiographic (X-ray film studies of the skeletal breathing pump in extant birds and alligators, and study of skeletal structure in historic fossil specimens. In this report we present various lines of skeletal evidence that indicate that pterosaurs had a highly effective flow-through respiratory system, capable of sustaining powered flight, predating the appearance of an analogous breathing system in birds by approximately seventy million years. Convergent evolution of gigantism in several Cretaceous pterosaur lineages was made possible through body density reduction by expansion of the pulmonary air sac system throughout the trunk and the distal limb girdle skeleton, highlighting the importance of respiratory adaptations in pterosaur evolution, and the dramatic effect of the release of physical constraints on morphological diversification and evolutionary radiation.

Respiratory evolution facilitated the origin of pterosaur flight and aerial gigantism.

Science.gov (United States)

Claessens, Leon P A M; O'Connor, Patrick M; Unwin, David M

2009-01-01

Pterosaurs, enigmatic extinct Mesozoic reptiles, were the first vertebrates to achieve true flapping flight. Various lines of evidence provide strong support for highly efficient wing design, control, and flight capabilities. However, little is known of the pulmonary system that powered flight in pterosaurs. We investigated the structure and function of the pterosaurian breathing apparatus through a broad scale comparative study of respiratory structure and function in living and extinct archosaurs, using computer-assisted tomographic (CT) scanning of pterosaur and bird skeletal remains, cineradiographic (X-ray film) studies of the skeletal breathing pump in extant birds and alligators, and study of skeletal structure in historic fossil specimens. In this report we present various lines of skeletal evidence that indicate that pterosaurs had a highly effective flow-through respiratory system, capable of sustaining powered flight, predating the appearance of an analogous breathing system in birds by approximately seventy million years. Convergent evolution of gigantism in several Cretaceous pterosaur lineages was made possible through body density reduction by expansion of the pulmonary air sac system throughout the trunk and the distal limb girdle skeleton, highlighting the importance of respiratory adaptations in pterosaur evolution, and the dramatic effect of the release of physical constraints on morphological diversification and evolutionary radiation.

Geologic evolution of the Lost City Hydrothermal Field

Science.gov (United States)

Denny, Alden R.; Kelley, Deborah S.; Früh-Green, Gretchen L.

2016-02-01

The Lost City Hydrothermal Field (LCHF) is a novel serpentinite-hosted vent field located on the Atlantis Massif southern wall. Results of 2 m resolution bathymetry, side scan, and video and still imagery, integrated with direct submersible observations provide the first high-resolution geologic map of the LCHF. These data form the foundation for an evolutionary model for the vent system over the past >120,000 years. The field is located on a down-dropped bench 70 m below the summit of the massif. The bench is capped by breccia and pelagic carbonate deposits underlain by variably deformed and altered serpentinite and gabbroic rocks. Hydrothermal activity is focused at the 60 m tall, 100 m across, massive carbonate edifice "Poseidon," which is venting 91°C fluid. Hydrothermal activity declines south and west of the Poseidon complex and dies off completely at distances greater than 200 m. East of Poseidon, the most recent stage of hydrothermal flow is characterized by egress of diffuse fluids from narrow fissures within a low-angle, anastomosing mylonite zone. South of the area of current hydrothermal activity, there is evidence of two discrete previously unrecognized relict fields. Active venting sites defined by carbonate-filled fissures that cut the carbonate cap rock at the summit of the massif mark the present-day northernmost extent of venting. These spatial relationships reflect multiple stages of field development, the northward migration of venting over time, and the likely development of a nascent field at the massif summit.

A phenology of the evolution of endothermy in birds and mammals.

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Lovegrove, Barry G

2017-05-01

Recent palaeontological data and novel physiological hypotheses now allow a timescaled reconstruction of the evolution of endothermy in birds and mammals. A three-phase iterative model describing how endothermy evolved from Permian ectothermic ancestors is presented. In Phase One I propose that the elevation of endothermy - increased metabolism and body temperature (T b ) - complemented large-body-size homeothermy during the Permian and Triassic in response to the fitness benefits of enhanced embryo development (parental care) and the activity demands of conquering dry land. I propose that Phase Two commenced in the Late Triassic and Jurassic and was marked by extreme body-size miniaturization, the evolution of enhanced body insulation (fur and feathers), increased brain size, thermoregulatory control, and increased ecomorphological diversity. I suggest that Phase Three occurred during the Cretaceous and Cenozoic and involved endothermic pulses associated with the evolution of muscle-powered flapping flight in birds, terrestrial cursoriality in mammals, and climate adaptation in response to Late Cenozoic cooling in both birds and mammals. Although the triphasic model argues for an iterative evolution of endothermy in pulses throughout the Mesozoic and Cenozoic, it is also argued that endothermy was potentially abandoned at any time that a bird or mammal did not rely upon its thermal benefits for parental care or breeding success. The abandonment would have taken the form of either hibernation or daily torpor as observed in extant endotherms. Thus torpor and hibernation are argued to be as ancient as the origins of endothermy itself, a plesiomorphic characteristic observed today in many small birds and mammals. © 2016 Cambridge Philosophical Society.

Current status of spent fuel disposal program in Taiwan, Republic of China

International Nuclear Information System (INIS)

Soong, K.L.; Liu, S.J.

1989-01-01

In the year of 1988, Taiwan has completed a two-year preliminary study and began in late 1988 a second term for the final disposal of spent fuel program. The research conducted in the first phase was mainly concentrated on the reviews of international studies and domestic geological literatures, set-up of siting criteria, and pertinent engineering analysis of a repository. Taiwan is an area of complex and unstable geological structures, abundant ground water and high density of population. Favorable host rocks under consideration for permanent waste disposal are thick shales and mudstones, metamorphosed rocks of mesozoic basement, solidified quartzite and mesozoic granitic gneiss. The analysis of heat transfer for hypothetical case studies indicate that the temperature rises in the repository systems would be well below the proposed maximum admissible temperatures. The repository size would be less than 2 km 2 when appropriate period for surface storage of spent fuel is satisfied. A probabilistic risk analysis also demonstrates that the presence of faulting and other tectonic instabilities characterize Taiwan's disadvantages for geological disposal of nuclear waste

Fire feedbacks over geological time and the evolution of atmospheric oxygen concentration

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Mills, B.; Belcher, C.; Lenton, T. M.

2017-12-01

During the 4.5 billion year history of the Earth, the concentration of oxygen in the atmosphere has risen from trace levels to today's 21%. Yet over the last 400 million years, O2 concentration appears to have remained within a relatively narrow range (around 15% - 30%), despite dramatic changes in the nature of global biogeochemical cycling. This stability has been crucial for continued animal evolution, and is thought to have arisen through feedbacks between oxygen, wildfire and plant productivity: the strong oxygen- dependence of fire initiation and spread means that global photosynthetic primary productivity is suppressed when oxygen levels are high, and enhanced when levels are low. We present biogeochemical modelling of the long term carbon and oxygen cycles, which aims to capture the operation of the wildfire feedback alongside other key processes. We find that wildfire can effectively stabilize long term oxygen concentrations, but that the nature of this feedback has changed as plant evolution has provided different fuels. Specifically, the evolution of early angiosperms during the Cretaceous period provided new understory fuels that more easily facilitated crown and canopy fires. Adding these dynamics to our model produces a more stable system over long timescales, and the model predicts that oxygen concentration has declined towards the present day - a prediction that is supported by other independent estimates.

Applications of geological labs on chip for CO_2 storage issues

International Nuclear Information System (INIS)

Morais, Sandy

2016-01-01

CO_2 geological storage in deep saline aquifers represents a mediation solution for reducing the anthropogenic CO_2 emissions. Consequently, this kind of storage requires adequate scientific knowledge to evaluate injection scenarios, estimate reservoir capacity and assess leakage risks. In this context, we have developed and used high pressure/high temperature micro-fluidic tools to investigate the different mechanisms associated with CO_2 geological storage in deep saline aquifers. The silicon-Pyrex 2D porous networks (Geological Labs On Chips) can replicate the reservoir p,T conditions (25 ≤ T ≤ 50 C, 50 ≤ p ≤ 10 MPa), geological and topological properties. This thesis manuscript first highlights the strategies developed during this work to fabricate the GLoCs and to access to global characteristics of our porous media such as porosity and permeability, which are later compared to numerical modelling results. The carbon dioxide detection in GLoCs mimicking p,T conditions of geological reservoirs by using the direct integration of optical fiber for IR spectroscopy is presented. I then detail the strategies for following the dissolution of carbonates in GLoCs with X-rays laminography experiments.Then, the manuscript focuses on the use of GLoCs to investigate each CO_2 trapping mechanism at the pore scale. The direct optical visualization and image processing allow us to follow the evolution of the injected CO_2/aqueous phase within the reservoir, including displacement mechanisms and pore saturation levels. Eventually, I present the ongoing works such as experiments with reactive brines and hydrates formations in porous media [fr

A diminutive perinate European Enantiornithes reveals an asynchronous ossification pattern in early birds.

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Knoll, Fabien; Chiappe, Luis M; Sanchez, Sophie; Garwood, Russell J; Edwards, Nicholas P; Wogelius, Roy A; Sellers, William I; Manning, Phillip L; Ortega, Francisco; Serrano, Francisco J; Marugán-Lobón, Jesús; Cuesta, Elena; Escaso, Fernando; Sanz, Jose Luis

2018-03-05

Fossils of juvenile Mesozoic birds provide insight into the early evolution of avian development, however such fossils are rare. The analysis of the ossification sequence in these early-branching birds has the potential to address important questions about their comparative developmental biology and to help understand their morphological evolution and ecological differentiation. Here we report on an early juvenile enantiornithine specimen from the Early Cretaceous of Europe, which sheds new light on the osteogenesis in this most species-rich clade of Mesozoic birds. Consisting of a nearly complete skeleton, it is amongst the smallest known Mesozoic avian fossils representing post-hatching stages of development. Comparisons between this new specimen and other known early juvenile enantiornithines support a clade-wide asynchronous pattern of osteogenesis in the sternum and the vertebral column, and strongly indicate that the hatchlings of these phylogenetically basal birds varied greatly in size and tempo of skeletal maturation.

Study on geology and geological structure based on literature studies

International Nuclear Information System (INIS)

Funaki, Hironori; Ishii, Eiichi; Yasue, Ken-ichi; Takahashi, Kazuharu

2005-03-01

Japan Nuclear Cycle Development Institute (JNC) is proceeding with underground research laboratory (URL) project for the sedimentary rock in Horonobe, Hokkaido. This project is an investigation project which is planned over 20 years. Surface-based investigations (Phase 1) have been conducted for the present. The purposes of the Phase 1 are to construct the geological environment model (geological-structural, hydrogeological, and hydrochemical models) and to confirm the applicability of investigation technologies for the geological environment. The geological-structural model comprises the base for the hydrogeological and hydrochemical models. We constructed the geological-structural model by mainly using data obtained from literature studies. Particulars regarding which data the model is based on and who has performed the interpretation are also saved for traceability. As a result, we explain the understanding of degree and the need of information on stratigraphy and discontinuous structure. (author)

Hydrogeological Properties of Geological Elements in Geological Model around KURT

Energy Technology Data Exchange (ETDEWEB)

Park, Kyung Woo; Kim, Kyung Soo; Koh, Yong Kwon; Choi, Jong Won [Korea Atomic Energy Institue, Daejeon (Korea, Republic of)

2012-09-15

To develop site characterization technologies for a radioactive waste disposal research in KAERI, the geological and hydrogeological investigations have been carried out since 1997. In 2006, the KURT (KAERI Underground Research Tunnel) was constructed to study a solute migration, a microbiology and an engineered barrier system as well as deeply to understand geological environments in in-situ condition. This study is performed as one of the site characterization works around KURT. Several investigations such as a lineament analysis, a borehole/tunnel survey, a geophyscial survey and logging in borehole, were used to construct the geological model. As a result, the geological model is constructed, which includes the lithological model and geo-structural model in this study. Moreover, from the results of the in-situ hydraulic tests, the hydrogeological properties of elements in geological model were evaluated.

Hydrogeological Properties of Geological Elements in Geological Model around KURT

International Nuclear Information System (INIS)

Park, Kyung Woo; Kim, Kyung Soo; Koh, Yong Kwon; Choi, Jong Won

2012-01-01

To develop site characterization technologies for a radioactive waste disposal research in KAERI, the geological and hydrogeological investigations have been carried out since 1997. In 2006, the KURT (KAERI Underground Research Tunnel) was constructed to study a solute migration, a microbiology and an engineered barrier system as well as deeply to understand geological environments in in-situ condition. This study is performed as one of the site characterization works around KURT. Several investigations such as a lineament analysis, a borehole/tunnel survey, a geophyscial survey and logging in borehole, were used to construct the geological model. As a result, the geological model is constructed, which includes the lithological model and geo-structural model in this study. Moreover, from the results of the in-situ hydraulic tests, the hydrogeological properties of elements in geological model were evaluated.

Biogeographical patterns of Myrcia s.l. (Myrtaceae) and their correlation with geological and climatic history in the Neotropics.

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Santos, Matheus Fortes; Lucas, Eve; Sano, Paulo Takeo; Buerki, Sven; Staggemeier, Vanessa Graziele; Forest, Félix

2017-03-01

Many recent studies discuss the influence of climatic and geological events in the evolution of Neotropical biota by correlating these events with dated phylogenetic hypotheses. Myrtaceae is one of the most diverse Neotropical groups and it therefore a good proxy of plant diversity in the region. However, biogeographic studies on Neotropical Myrtaceae are still very limited. Myrcia s.l. is an informal group comprising three accepted genera (Calyptranthes, Marlierea and Myrcia) making up the second largest Neotropical group of Myrtaceae, totalling about 700 species distributed in nine subgroups. Exclusively Neotropical, the group occurs along the whole of the Neotropics with diversity centres in the Caribbean, the Guiana Highlands and the central-eastern Brazil. This study aims to identify the time and place of divergence of Myrcia s.l. lineages, to examine the correlation in light of geological and climatic events in the Neotropics, and to explore relationships among Neotropical biogeographic areas. A dated phylogenetic hypothesis was produced using BEAST and calibrated by placing Paleomyrtinaea princetonensis (56Ma) at the root of the tree; biogeographic analysis used the DEC model with dispersal probabilities between areas based on distance and floristic affinities. Myrcia s.l. originated in the Montane Atlantic Forest between the end of Eocene and early Miocene and this region acted as a secondary cradle for several lineages during the evolution of this group. The Caribbean region was important in the diversification of the Calyptranthes clade while the Guayana shield appears as ancestral area for an older subgroup of Myrcia s.l. The Amazon Forest has relatively low diversity of Myrcia s.l. species but appears to have been important in the initial biogeographic history of old lineages. Lowland Atlantic Forest has high species diversity but species rich lineages did not originate in the area. Diversification of most subgroups of Myrcia s.l. occurred throughout

Destination: Geology?

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Price, Louise

2016-04-01

"While we teach, we learn" (Roman philosopher Seneca) One of the most beneficial ways to remember a theory or concept is to explain it to someone else. The offer of fieldwork and visits to exciting destinations is arguably the easiest way to spark a students' interest in any subject. Geology at A-Level (age 16-18) in the United Kingdom incorporates significant elements of field studies into the curriculum with many students choosing the subject on this basis and it being a key factor in consolidating student knowledge and understanding. Geology maintains a healthy annual enrollment with interest in the subject increasing in recent years. However, it is important for educators not to loose sight of the importance of recruitment and retention of students. Recent flexibility in the subject content of the UK curriculum in secondary schools has provided an opportunity to teach the basic principles of the subject to our younger students and fieldwork provides a valuable opportunity to engage with these students in the promotion of the subject. Promotion of the subject is typically devolved to senior students at Hessle High School and Sixth Form College, drawing on their personal experiences to engage younger students. Prospective students are excited to learn from a guest speaker, so why not use our most senior students to engage and promote the subject rather than their normal subject teacher? A-Level geology students embarking on fieldwork abroad, understand their additional responsibility to promote the subject and share their understanding of the field visit. They will typically produce a series of lessons and activities for younger students using their newly acquired knowledge. Senior students also present to whole year groups in seminars, sharing knowledge of the location's geology and raising awareness of the exciting destinations offered by geology. Geology fieldwork is always planned, organised and led by the member of staff to keep costs low, with recent visits

Diets of giants: the nutritional value of herbivorous dinosaur diet during the Mesozoic

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Gill, Fiona; Hummel, Juergen; Sharifi, Reza; Lee, Alexandra; Lomax, Barry

2017-04-01

A major uncertainty in estimating energy budgets and population densities of extinct animals is the carrying capacity of their ecosystems, constrained by net primary productivity (NPP) and digestible energy content of that NPP. The hypothesis that increases in NPP of land plants due to elevated atmospheric CO2 contributed to the unparalleled size of the sauropods, the largest ever land animals, has recently been rejected, based on modern studies on herbivorous insects. However, the nutritional value of plants grown under elevated CO2 levels might be very different for vertebrate megaherbivores with more complex digestive systems and different protein:energy requirements than insects. Here we show that the metabolisable energy (ME) value of five species of potential dinosaur food plants does not decline consistently with increasing CO2 growth concentrations, with maxima observed at 1200 ppm CO2. Our data potentially rebut the hypothesis of constraints on herbivore diet quality in the Mesozoic due to CO2 levels.

A transitional alkalic dolerite dike suite of Mesozoic age in Southeastern New England

Science.gov (United States)

Hermes, O. Don; Rao, J. M.; Dickenson, M. P.; Pierce, T. A.

1984-12-01

Dike rocks from the New England platform of Rhode Island and adjacent Massachusetts consist of premetamorphic and post-metamorphic suites. The older group includes metamorphosed dolerite, minette, and schistose dioritic rocks. Post-metamorphic dikes consist of dolerite and sparse monchiquite. The post-metamorphic dolerites are of comparable age to the Eastern North American dolerite suite associated with the Mesozoic basins along the eastern seaboard of North America. However, the southeastern New England dolerites exhibit mineralogy and chemistry more typical of a transitional alkalic suite compared to the more subalkalic tholeiitic dolerites of the Eastern North American suite. Both suites are compatible with a rift tectonic setting, but the more alkalic dolerites may represent a deeper source of small volume melts compared to the Eastern North American dolerites. These more alkaline melts may have concentrated at local centers, or they may be typical of flank dolerites as opposed to the less alkalic varieties that occur within the central axial rift.

Site descriptive modelling during characterization for a geological repository for nuclear waste in Sweden

International Nuclear Information System (INIS)

Stroem, A.; Andersson, J.; Skagius, K.; Winberg, A.

2008-01-01

The Swedish programme for geological disposal of spent nuclear fuel is approaching major milestones in the form of permit applications for an encapsulation plant and a deep geologic repository. This paper presents an overview of the bedrock and surface modelling work that comprises a major part of the on-going site characterization in Sweden and that results in syntheses of the sites, called site descriptions. The site description incorporates descriptive models of the site and its regional setting, including the current state of the geosphere and the biosphere as well as natural processes affecting long-term evolution. The site description is intended to serve the needs of both repository engineering with respect to layout and construction, and safety assessment, with respect to long-term performance. The development of site-descriptive models involves a multi-disciplinary interpretation of geology, rock mechanics, thermal properties, hydrogeology, hydrogeochemistry, transport properties and ecosystems using input in the form of available data for the surface and from deep boreholes

Field Geology/Processes

Science.gov (United States)

Allen, Carlton; Jakes, Petr; Jaumann, Ralf; Marshall, John; Moses, Stewart; Ryder, Graham; Saunders, Stephen; Singer, Robert

1996-01-01

The field geology/process group examined the basic operations of a terrestrial field geologist and the manner in which these operations could be transferred to a planetary lander. Four basic requirements for robotic field geology were determined: geologic content; surface vision; mobility; and manipulation. Geologic content requires a combination of orbital and descent imaging. Surface vision requirements include range, resolution, stereo, and multispectral imaging. The minimum mobility for useful field geology depends on the scale of orbital imagery. Manipulation requirements include exposing unweathered surfaces, screening samples, and bringing samples in contact with analytical instruments. To support these requirements, several advanced capabilities for future development are recommended. Capabilities include near-infrared reflectance spectroscopy, hyper-spectral imaging, multispectral microscopy, artificial intelligence in support of imaging, x ray diffraction, x ray fluorescence, and rock chipping.

Safety case development in the Japanese programme for geological disposal of HLW: Evolution in the generic stage

International Nuclear Information System (INIS)

Ueda, Hiroyoshi; Ishiguro, Katsuhiko; Takeuchi, Mitsuo; Fujihara, Hiroshi; Takeda, Seietsu

2014-01-01

In the Japanese programme for nuclear power generation, the safe management of the resulting radioactive waste, particularly vitrified high-level waste (HLW) from fuel reprocessing, has been a major concern and a focus of R and D since the late 70's. According to the specifications in a report issued by an advisory committee of the Japan Atomic Energy Commission (JAEC, 1997), the Second Progress Report on R and D for the Geological Disposal of HLW (H12 report) (JNC, 2000) was published after two decades of R and D activities and showed that disposal of HLW in Japan is feasible and can be practically implemented at sites which meet certain geological stability requirements. The H12 report supported government decisions that formed the basis of the 'Act on Final Disposal of Specified Radioactive Waste' (Final Disposal Act), which came into force in 2000. The Act specifies deep geological disposal of HLW at depths greater than 300 metres, together with a stepwise site selection process in three stages. Following the Final Disposal Act, the supporting 'Basic Policy for Final Disposal' and the 'Final Disposal Plan' were authorised in the same year. (authors)

Applications of Micro-Fourier Transform Infrared Spectroscopy (FTIR in the Geological Sciences—A Review

Directory of Open Access Journals (Sweden)

Yanyan Chen

2015-12-01

Full Text Available Fourier transform infrared spectroscopy (FTIR can provide crucial information on the molecular structure of organic and inorganic components and has been used extensively for chemical characterization of geological samples in the past few decades. In this paper, recent applications of FTIR in the geological sciences are reviewed. Particularly, its use in the characterization of geochemistry and thermal maturation of organic matter in coal and shale is addressed. These investigations demonstrate that the employment of high-resolution micro-FTIR imaging enables visualization and mapping of the distributions of organic matter and minerals on a micrometer scale in geological samples, and promotes an advanced understanding of heterogeneity of organic rich coal and shale. Additionally, micro-FTIR is particularly suitable for in situ, non-destructive characterization of minute microfossils, small fluid and melt inclusions within crystals, and volatiles in glasses and minerals. This technique can also assist in the chemotaxonomic classification of macrofossils such as plant fossils. These features, barely accessible with other analytical techniques, may provide fundamental information on paleoclimate, depositional environment, and the evolution of geological (e.g., volcanic and magmatic systems.

The Dom Feliciano belt and its relations with the craton of the Rio de la Plata and Punta del Este ground-Geology and geochronology

International Nuclear Information System (INIS)

Preciozzi, F.; Peel, E.; Sanchez, L.; Basei, M.; Ledesma, J.; Muzio, R.

2005-01-01

This research was framed in an interdisciplinary project, whose main objective was to make an approach to the geological, tectonic and geochronological evolution of Dom Feliciano Belt and adjacent land partners, especially the Río de la Plata Craton and Land Punta del Este. As was proposed in the project, special attention to geochronological studies from geological transects lent controlled. This yielded the expected level major step forward, not only with regard to the age of different units, but what makes the establishment of an adequate stratigraphy of them. Similarly, geochemical, petrographic and geochronological studies allowed essentially make geotectonic and geologic correlations with the southern portion of Brazil and the western portion of the land I africanos.lo expand involving more project goals in si.En effect began to manifest as a need to know the evolution of equivalent units both in the southern portion of Brazil and Africa Occidental.Estos fundamentalmnete work with West Africa were made with contributions from CONICYT Project 6009 under Projects Geological Correlation 438, 450 and 478 .this pertimitio exchange ideas with leading scientists worldwide many of whom ended up collaborating with it

Bedrock geologic map of the Lisbon quadrangle, and parts of the Sugar Hill and East Haverhill quadrangles, Grafton County, New Hampshire

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Rankin, Douglas W.

2018-04-20

The bedrock geologic map of the Lisbon quadrangle, and parts of the Sugar Hill and East Haverhill quadrangles, Grafton County, New Hampshire, covers an area of approximately 73 square miles (189 square kilometers) in west-central New Hampshire. This map was created as part of a larger effort to produce a new bedrock geologic map of Vermont through the collection of field data at a scale of 1:24,000. A large part of the map area consists of the Bronson Hill anticlinorium, a post-Early Devonian structure that is cored by metamorphosed Cambrian to Devonian sedimentary, volcanic, and plutonic rocks.The Bronson Hill anticlinorium is the apex of the Middle Ordovician to earliest-Silurian Bronson Hill magmatic arc that contains the Ammonoosuc Volcanics, Partridge Formation, and Oliverian Plutonic Suite, and extends from Maine, through western New Hampshire (down the eastern side of the Connecticut River), through southern New England to Long Island Sound. The deformed and partially eroded arc is locally overlain by a relatively thin Silurian section of metasedimentary rocks (Clough Quartzite and Fitch Formation) that thickens to the east. The Silurian section near Littleton is disconformably overlain by a thicker, Lower Devonian section that includes mostly metasedimentary and minor metavolcanic rocks of the Littleton Formation. The Bronson Hill anticlinorium is bisected by a series of northeast-southwest trending Mesozoic normal faults. Primarily among them is the steeply northwest-dipping Ammonoosuc fault that divides older and younger units (lower and upper sections) of the Ammonoosuc Volcanics. The Ammonoosuc Volcanics are lithologically complex and predominantly include interlayered and interfingered rhyolitic to basaltic volcanic and volcaniclastic rocks, as well as lesser amounts of slate, phyllite, ironstone, chert, sandstone, and pelite. The Albee Formation underlies the Ammonoosuc Volcanics and is predominantly composed of interbedded metamorphosed sandstone

Brazil Geologic Basic Survey Program - Barbacena - Sheet SF.23-X-C-III -Minas Gerais State

International Nuclear Information System (INIS)

Brandalise, L.A.

1991-01-01

The present report refers to the Barbacena sheet (SF.23-X-C-III) systematic geological mapping, on the 1:10,000 scale, related to the Levantamentos Geologicos Basicos do Brasil Program - PLGB, carried out by CPRM for the DNPM. Integrated to geochemical and geophysical surveys, the geological mapping not only yielded geophysical and geochemical maps but a consistent to the 1:100.000 scale Metallogenetic/Provisional one as well. The geological mapping carried out during the Project has really evidenced that samples of distinct stratigraphic units had been employed to define the one and only isochrone. However geochronologic Rb/Sr dating performed during the geological mapping phase evidenced Archean ages for rocks of the Sao Bento dos Torres Metamorphic Suite (2684 ± 110 m.y.) and ages of about 2000 m.y. for the Ressaquinha Complex rocks. An analysis of crustal evolution patterns based on geological mapping, gravimetric survey data, aeromagnetometry and available geochronologic data is given in the Chapter 6, Part II, in the test. Major element oxides, trace-elements and rare-earths elements were analysed to establish parameters for the rocks environment elucidation. Geochemical survey was carried out with base on pan concentrated and stream sediments distributed throughout the sheet. (author)

Global Journal of Geological Sciences

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Global Journal of Geological Sciences is aimed at promoting research in all areas of Geological Sciences including geochemistry, geophysics, engineering geology, hydrogeology, petrology, mineralogy, geochronology, tectonics, mining, structural geology, marine geology, space science etc. Visit the Global Journal Series ...

Andean Basin Evolution Associated with Hybrid Thick- and Thin-Skinned Deformation in the Malargüe Fold-Thrust Belt, Western Argentina

Science.gov (United States)

Horton, B. K.; Fuentes, F.

2015-12-01

Andean deformation and basin evolution in the Malargüe fold-thrust belt of western Argentina (34-36°S) has been dominated by basement faults influenced by pre-existing Mesozoic rift structures of the hydrocarbon-rich Neuquen basin. However, the basement structures diverge from classic inversion structures, and the associated retroarc basin system shows a complex Mesozoic-Cenozoic history of mixed extension and contraction, along with an enigmatic early Cenozoic stratigraphic hiatus. New results from balanced structural cross sections (supported by industry seismic, well data, and surface maps), U-Pb geochronology, and foreland deposystem analyses provide improved resolution to examine the duration and kinematic evolution of Andean mixed-mode deformation. The basement structures form large anticlines with steep forelimbs and up to >5 km of structural relief. Once the propagating tips of the deeper basement faults reached cover strata, they fed slip to shallow thrust systems that were transported in piggyback fashion by newly formed basement structures, producing complex structural relationships. Detrital zircon U-Pb ages for the 5-7 km-thick basin fill succession reveal shifts in sedimentation pathways and accumulation rates consistent with (1) local basement sources during Early-Middle Jurassic back-arc extension, (2) variable cratonic and magmatic arc sources during Late Jurassic-Cretaceous postrift thermal subsidence, and (3) Andean arc and thrust-belt sources during irregular Late Cretaceous-Cenozoic shortening. Although pulses of flexural subsidence can be attributed to periods of fault reactivation (inversion) and geometrically linked thin-skinned thrusting, fully developed foreland basin conditions were only achieved in Late Cretaceous and Neogene time. Separating these two contractional episodes is an Eocene-lower Miocene (roughly 40-20 Ma) depositional hiatus within the Cenozoic succession, potentially signifying forebulge passage or neutral to

Paleoclimatic and paleolatitude settings of accumulation of radiolarian siliceous-volcanogenic sequences in the middle Mesozoic Pacific: Evidence from allochthons of East Asia

Science.gov (United States)

Vishnevskaya, V. S.; Filatova, N. I.

2017-09-01

Jurassic-Cretaceous siliceous-volcanogenic rocks from nappes of tectonostratigraphic sequences of the East Asia Middle Cretaceous Okhotsk-Koryak orogenic belt are represented by a wide range of geodynamic sedimentation settings: oceanic (near-spreading zones, seamounts, and deep-water basins), marginal seas, and island arcs. The taxonomic compositions of radiolarian communities are used as paleolatitude indicators in the Northern Pacific. In addition, a tendency toward climate change in the Mesozoic is revealed based on these communities: from the warm Triassic to the cold Jurassic with intense warming from the Late Jurassic to the Early Cretaceous. Cretaceous warming led to heating of ocean waters even at moderately high latitudes and to the development of Tethyan radiolarians there. These data are confirmed by a global Cretaceous temperature peak coinciding with a high-activity pulse of the planetary mantle superplume system, which created thermal anomalies and the greenhouse effect. In addition, the Pacific superplume attributed to this system caused accelerated movement of oceanic plates, which resulted in a compression setting on the periphery of the Pacific and the formation of the Okhotsk-Koryak orogenic belt on its northwestern framing in the Middle Cretaceous, where Mesozoic rocks of different geodynamic and latitudinal-climate settings were juxtaposed into allochthonous units.

Petroleum investment opportunities in Manitoba: A geological, engineering and economic perspective

International Nuclear Information System (INIS)

Fox, J.N.; Martinuk, C.D.

1994-01-01

The geology and reservoir characteristics of Manitoba's oil producing horizons are described, and exploration and development prospects are reviewed. Southwestern Manitoba occupies part of the northeastern flank of the Williston Basin. Paleozoic, Mesozoic, and Cenozoic rocks form a basinward thickening wedge of sedimentary strata that reach a total thickness of 2,300 m in the southwest corner of the province. To date, oil production in Manitoba is restricted to the sandstones of the Middle Jurassic, the Jurassic Amaranth Formation, the Mississippian Bakken Formation, and the carbonates of the Mississippian Lodgepole and Mission Canyon Formations. The deeper Ordovician, Silurian, and Devonian formations offer oil and gas potential but remain largely undrilled. Total recoverable reserves are ca 36 million m 3 and remaining proved reserves are ca 6 million m 3 . Manitoba had a resurgence in petroleum activity in 1993; 102 wells were licensed, compared to an annual average of 61 over the past five years. More Crown land was disposed at the two lease sales in 1993 than had been leased in the previous five years. Low Crown land price is one competitive advantage available to Manitoba oil producers. Other advantages include low drilling and completion costs, low drilling density, a competitive and stable fiscal regime, drilling and exploration incentives, and unrestricted access to markets. Sample economics are included to illustrate the attractiveness of vertical and horizontal drilling opportunities in Manitoba. 8 refs., 6 figs., 7 tabs

Geological boundary conditions for a safety demonstration and verification concept for a HLW repository in claystone in Germany. AnSichT

Energy Technology Data Exchange (ETDEWEB)

Stark, Lena; Bebiolka, Anke; Gerardi, Johannes [Federal Institute for Geosciences and Natural Resources (BGR), Hannover (Germany). Dept. of Underground Space for Storage and Economic Use; and others

2015-07-01

Within the framework of the R and D project ''AnSichT'', DBE TECHNOLOGY, BGR and GRS are developing a method to demonstrate the safety of a HLW repository in claystone in Germany. The methodological approach basing on a holistic concept, links the legal and geologic boundary conditions, the disposal and closure concept, the demonstration of barrier integrity, and the long-term analysis of the repository evolution as well. The geologic boundary conditions are specified by the description of the geological situation and generic models, the selection of representative parameters and geoscientific long-term predictions. They form a fundament for the system analysis.

Research on geological disposal: R and D concept on geological disposal

International Nuclear Information System (INIS)

1993-01-01

The objective on geological disposal of high-level radioactive wastes are to ensure the long term radiological protection of the human and his environment in accordance with current internationally agreed radiation protection principles. The principle of geological disposal is to settle the high-level wastes in deep underground so as to isolate them from the human and his environment considering the existence of groundwater. Japan is currently in the stage of assessing technical feasibility of geological disposal to the extent practicable. In accordance with the AEC (Atomic Energy Commission) policy in 1989, PNC (Power Reactor and Nuclear Fuel Development Corporation) has conducted the research and development on geological disposal in three areas: 1) studies of geological environment, 2) research and development of disposal technology, and 3) performance assessment study. (author)

Research on the evolution model and deformation mechanisms of Baishuihe landslide based on analyzing geologic process of slope

Science.gov (United States)

Zhang, S.; Tang, H.; Cai, Y.; Tan, Q.

2016-12-01

The landslide is a result of both inner and exterior geologic agents, and inner ones always have significant influences on the susceptibility of geologic bodies to the exterior ones. However, current researches focus more on impacts of exterior factors, such as precipitation and reservoir water, than that of geologic process. Baishuihe landslide, located on the south bank of Yangtze River and 56km upstream from the Three Gorges Project, was taken as the study subject with the in-situ investigation and exploration carried out for the first step. After the spatial analysis using the 3D model of topography built by ArcGIS (Fig.1), geologic characteristics of the slope that lies in a certain range near the Baishuihe landslide on the same bank were investigated for further insights into geologic process of the slope, with help of the geological map and structure outline map. Baishuihe landslide developed on the north limb of Baifuping anticline, a dip slope on the southwest margin of Zigui basin. The eastern and western boundaries are both ridges and in the middle a distinct slide depression is in process of deforming. Evolutionary process of Baishuihe landslide includes three steps below. 1) Emergence of Baifuping anticline leaded to interbedded dislocation, tension cracks and joint fractures in bedrocks. 2) Weathering continuously weakened strength of soft interlayers in the Shazhenxi Formation (T3s). 3) Rock slide caused by neotectonics happened on a large scale along the weak layers and joint planes, forming initial Baishuihe landslide. Although the landslide has undergone reconstruction for a long time, it could still be divided clearly into two parts, namely a) the rock landslide at the back half (south) and b) the debris landslide at the front half (north). a) The deformation mechanism for the rock landslide is believed to be deterioration in strength of weak bedding planes due to precipitation and free face caused by human activities or river incision. b

Introductory Geology From the Liberal Arts Approach: A Geology-Sociology Linked Course

Science.gov (United States)

Walsh, E. O.; Davis, E.

2008-12-01

Geology can be a hard sell to college students, especially to college students attending small, liberal arts institutions in localities that lack exaggerated topography. At these schools, Geology departments that wish to grow must work diligently to attract students to the major; professors must be able to convince a wider audience of students that geology is relevant to their everyday lives. Toward this end, a Physical Geology course was linked with an introductory Sociology course through the common theme of Consumption. The same students took the two courses in sequence, beginning with the Sociology course and ending with Physical Geology; thus, students began by discussing the role of consumption in society and ended by learning about the geological processes and implications of consumption. Students were able to ascertain the importance of geology in their daily lives by connecting Earth processes to specific products they consume, such as cell phones and bottled water. Students were also able to see the connection between seemingly disparate fields of study, which is a major goal of the liberal arts. As a theme, Consumption worked well to grab the attention of students interested in diverse issues, such as environmental science or social justice. A one-hour lecture illustrating the link between sociology and geology was developed for presentation to incoming freshmen and their parents to advertise the course. Initial response has been positive, showing an increase in awareness of geological processes among students with a wide range of interests.

The lithosphere structure and deep processes of the Mesozoic metallogenic belt in eastern China: constraints from passive and active seismic methods

Science.gov (United States)

Lu, Q.; Shi, D.; Jiang, G.; Yan, J.

2013-12-01

The lithosphere structure and deep processes are keys to understanding mineral system and ore-forming processes. Lithosphere-scale process could create big footprints or signatures which can be observed by geophysics methods. SinoProbe-03 has conducted a Transect exploration across middle and lower Yangtze Metallogenic Belt (YMT) in Eastern China. Broadband seismic, reflection seismic, wide-angle reflection and magnetotellurics survey were carried out along the Transect. Seismic reflection profiles and MT survey were also performed in Luzong, Tongling and Ningwu ore districts to construct 3D geological model. The resulting geophysical data provides new information which help to better understanding the lithosphere structure, deep processes and deformation history of the Metallogenic Belt. The major results are: (1) Lower velocity body at the top of upper mantle and a SE dipping high velocity body were imaged by teleseismic tomography beneath YMB; (2) Shear wave splitting results show NE parallel fast-wave polarization direction which parallel with tectonic lineament; (3) The reflection seismic data support the crustal-detachment model, the lower and upper crust was detached during contraction deformation near Tanlu fault and Ningwu volcanic basin; (4) Broadband and reflection seismic confirm the shallow Moho beneath YMB; (5) Strong correlation of lower crust reflectivity with magmatism; (6) The lower crust below Luzong Volcanics shows obvious reflective anisotropy both at the crust-mantle transition and the brittle-ductile transition in the crust. All these features suggest that introcontinental subduction, lithosphere delamination, mantle sources magmatic underplating, and MASH process are responsible for the formation of this Mesozoic metallogenic belt. Acknowledgment: We acknowledge the financial support of SinoProbe by the Ministry of Finance and Ministry of Land and Resources, P. R. China, under Grant sinoprobe-03, and financial support by National Natural

Geology of the Southern Utopia Planitia Highland-Lowland Boundary Plain: First Year Results and Second Year Plan

Science.gov (United States)

Skinner, J. A., Jr.; Tanaka, K. L.; Hare, T. M.

2008-01-01

The southern Utopia highland-lowland boundary (HLB) extends >1500 km westward from northern Nepenthes Mensae to the topographic saddle that separates Isidis and Utopia Planitiae. It contains bench-like platforms that contain depressions, pitted cones (some organized into arcuate chains and thumbprint terrain), isolated domes, lineated depressions, buried circular depressions, ring fractures, polygonal fractures, and other locally- to regionally-dispersed landforms [1]. The objective of our mapping project is to clarify the geologic evolution of the southern Utopia Planitia HLB by identifying the geologic, structural, and stratigraphic relationships of surface materials in MTMs 10237, 15237, 20237, 10242, 15242, 20242, 10247, 15247, and 20247.

Goethe's Italian Journey and the geological landscape

Science.gov (United States)

Coratza, Paola; Panizza, Mario

2015-04-01

"integrated", meaning integration between natural components, including geological, biological and anthropogenic elements, climate, history, architecture, literature etc. Secondly, Goethe's scientific intuitions (in this case the geological ones) were compared with the evolution of scientific knowledge up to most recent times, which at times confirm what Goethe had already realised. This project is based on the description of the stages of his journey, in the light of modern results of investigations carried out in geology, geomorphology, mineralogy etc. This research is grateful for the contributions of many geologists from various universities and Italian research institutions from the Alps to Sicily. Goethe's Italian journey as revisited in this paper aims to stimulate the interest of the reader in the "geological" component of the environment in which we live by means of an "integrated" approach.

Mining inventory of Uruguay. Results of geochemical prospecting of Cerro Partido fotoplano

International Nuclear Information System (INIS)

Zeegers, H.; Artignan, D.; Vairon, P.

1982-01-01

This work is about the analitical results of the geological prospection carried out in Cerro Partido zone within the framework of Mining inventory of Uruguay. In this fotoplano (Esc. 1/50.000 and 1/400.000 there are metamorphic, mesozoic and carbonated formations

Tectonic and climatic considerations for deep geological disposal of radioactive waste: A UK perspective

International Nuclear Information System (INIS)

McEvoy, F.M.; Schofield, D.I.; Shaw, R.P.; Norris, S.

2016-01-01

Identifying and evaluating the factors that might impact on the long-term integrity of a deep Geological Disposal Facility (GDF) and its surrounding geological and surface environment is central to developing a safety case for underground disposal of radioactive waste. The geological environment should be relatively stable and its behaviour adequately predictable so that scientifically sound evaluations of the long-term radiological safety of a GDF can be made. In considering this, it is necessary to take into account natural processes that could affect a GDF or modify its geological environment up to 1 million years into the future. Key processes considered in this paper include those which result from plate tectonics, such as seismicity and volcanism, as well as climate-related processes, such as erosion, uplift and the effects of glaciation. Understanding the inherent variability of process rates, critical thresholds and likely potential influence of unpredictable perturbations represent significant challenges to predicting the natural environment. From a plate-tectonic perspective, a one million year time frame represents a very short segment of geological time and is largely below the current resolution of observation of past processes. Similarly, predicting climate system evolution on such time-scales, particularly beyond 200 ka AP is highly uncertain, relying on estimating the extremes within which climate and related processes may vary with reasonable confidence. The paper highlights some of the challenges facing a deep geological disposal program in the UK to review understanding of the natural changes that may affect siting and design of a GDF. - Highlights: • Natural processes are key to developing a safety case for geological disposal. • Key factors include plate tectonic and climate-mediated processes. • Process variability is a challenge to predicting the natural environment. • We highlight the challenges for geological disposal programs using

Tectonic and climatic considerations for deep geological disposal of radioactive waste: A UK perspective

Energy Technology Data Exchange (ETDEWEB)

McEvoy, F.M., E-mail: fmcevoy@bgs.ac.uk [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Schofield, D.I. [British Geological Survey, Tongwynlais, CF15 7NE (United Kingdom); Shaw, R.P. [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Norris, S. [Radioactive Waste Management Limited, B587, Curie Avenue, Harwell, Didcot OX11 0RH (United Kingdom)

2016-11-15

Identifying and evaluating the factors that might impact on the long-term integrity of a deep Geological Disposal Facility (GDF) and its surrounding geological and surface environment is central to developing a safety case for underground disposal of radioactive waste. The geological environment should be relatively stable and its behaviour adequately predictable so that scientifically sound evaluations of the long-term radiological safety of a GDF can be made. In considering this, it is necessary to take into account natural processes that could affect a GDF or modify its geological environment up to 1 million years into the future. Key processes considered in this paper include those which result from plate tectonics, such as seismicity and volcanism, as well as climate-related processes, such as erosion, uplift and the effects of glaciation. Understanding the inherent variability of process rates, critical thresholds and likely potential influence of unpredictable perturbations represent significant challenges to predicting the natural environment. From a plate-tectonic perspective, a one million year time frame represents a very short segment of geological time and is largely below the current resolution of observation of past processes. Similarly, predicting climate system evolution on such time-scales, particularly beyond 200 ka AP is highly uncertain, relying on estimating the extremes within which climate and related processes may vary with reasonable confidence. The paper highlights some of the challenges facing a deep geological disposal program in the UK to review understanding of the natural changes that may affect siting and design of a GDF. - Highlights: • Natural processes are key to developing a safety case for geological disposal. • Key factors include plate tectonic and climate-mediated processes. • Process variability is a challenge to predicting the natural environment. • We highlight the challenges for geological disposal programs using

Geologic framework and Cenozoic evolution of the Yucca Mountain area, Nevada

International Nuclear Information System (INIS)

Fox, K.F. Jr.; Spengler, R.W.; Myers, W.B.

1990-01-01

Yucca Mountain, Nevada, has been proposed as the site of a high-level nuclear waste repository. The purpose of this paper is to outline aspects of the geology and tectonics of the area which bear on its suitability as a waste repository. The repository is to be excavated from a non-lithophysal zone within the lower part of the Paintbrush Tuff. Revised estimates of the thickness of this zone indicate that the lower, down-dip extremity of the planned repository could be raised by as much as 130 m, thus reducing the grade within the repository and increasing the distance to the water table below. We note that because of the closely spaced fracturing and low in-situ stresses within the repository block, lateral support of fractured rock is likely to be poor. 30 refs., 5 figs

A Large Accumulation of Avian Eggs from the Late Cretaceous of Patagonia (Argentina) Reveals a Novel Nesting Strategy in Mesozoic Birds

Science.gov (United States)

Fernández, Mariela S.; García, Rodolfo A.; Fiorelli, Lucas; Scolaro, Alejandro; Salvador, Rodrigo B.; Cotaro, Carlos N.; Kaiser, Gary W.; Dyke, Gareth J.

2013-01-01

We report the first evidence for a nesting colony of Mesozoic birds on Gondwana: a fossil accumulation in Late Cretaceous rocks mapped and collected from within the campus of the National University of Comahue, Neuquén City, Patagonia (Argentina). Here, Cretaceous ornithothoracine birds, almost certainly Enanthiornithes, nested in an arid, shallow basinal environment among sand dunes close to an ephemeral water-course. We mapped and collected 65 complete, near-complete, and broken eggs across an area of more than 55 m2. These eggs were laid either singly, or occasionally in pairs, onto a sandy substrate. All eggs were found apparently in, or close to, their original nest site; they all occur within the same bedding plane and may represent the product of a single nesting season or a short series of nesting attempts. Although there is no evidence for nesting structures, all but one of the Comahue eggs were half-buried upright in the sand with their pointed end downwards, a position that would have exposed the pole containing the air cell and precluded egg turning. This egg position is not seen in living birds, with the exception of the basal galliform megapodes who place their eggs within mounds of vegetation or burrows. This accumulation reveals a novel nesting behaviour in Mesozoic Aves that was perhaps shared with the non-avian and phylogenetically more basal troodontid theropods. PMID:23613776

A large accumulation of avian eggs from the late cretaceous of patagonia (Argentina) reveals a novel nesting strategy in mesozoic birds.

Science.gov (United States)

Fernández, Mariela S; García, Rodolfo A; Fiorelli, Lucas; Scolaro, Alejandro; Salvador, Rodrigo B; Cotaro, Carlos N; Kaiser, Gary W; Dyke, Gareth J

2013-01-01

We report the first evidence for a nesting colony of mesozoic birds on Gondwana: a fossil accumulation in Late Cretaceous rocks mapped and collected from within the campus of the National University of Comahue, Neuquén City, Patagonia (Argentina). Here, Cretaceous ornithothoracine birds, almost certainly Enanthiornithes, nested in an arid, shallow basinal environment among sand dunes close to an ephemeral water-course. We mapped and collected 65 complete, near-complete, and broken eggs across an area of more than 55 m(2). These eggs were laid either singly, or occasionally in pairs, onto a sandy substrate. All eggs were found apparently in, or close to, their original nest site; they all occur within the same bedding plane and may represent the product of a single nesting season or a short series of nesting attempts. Although there is no evidence for nesting structures, all but one of the Comahue eggs were half-buried upright in the sand with their pointed end downwards, a position that would have exposed the pole containing the air cell and precluded egg turning. This egg position is not seen in living birds, with the exception of the basal galliform megapodes who place their eggs within mounds of vegetation or burrows. This accumulation reveals a novel nesting behaviour in Mesozoic Aves that was perhaps shared with the non-avian and phylogenetically more basal troodontid theropods.

Identification of scenarios in the safety assessment of a deep geological site for radioactive waste disposal

International Nuclear Information System (INIS)

Escalier des Orres, P.; Devillers, C.; Cernes, A.

1990-01-01

The selection and qualification procedure of a site for radioactive wastes disposal in a deep geologic formation, has begun in France in the early eighties. The public authorities, on ANDRA's proposal, has preselected in 1987 four sites, each of them corresponding to a type of geologic formations (granite, clay, salt and shale). Within two years, one of these sites will be chosen for the location of an underground laboratory. The safety analysis for the site's qualification uses evolution scenarios of the repository and its environment, chosen according to a deterministic method. With an appropriate detail level, are defined a reference scenario and scenario with random events. 4 refs., 1 tab [fr

Groundwater drought in different geological conditions

International Nuclear Information System (INIS)

Machlica, A; Stojkovova, M

2008-01-01

The identification of hydrological extremes (drought) is very actual at present. The knowledge of the mechanism of hydrological extremes evolution could be useful at many levels of human society, such as scientific, agricultural, local governmental, political and others. The research was performed in the Upper part of the Nitra River catchment (central part of Slovakia) and in the Topla and Ondava River catchments (eastern part of Slovakia). Lumped hydrological model BILAN was used to identify relationships among compounds of the water balance. Presented results are focused on drought in groundwater storage, soil moisture, base flow and discharges. BFI model for baseflow estimation was used and results were compared with those gained by BILAN model. Another item of the research was to compare results of hydrological balance model application on catchments with different geological conditions.

Study on Sr-Nd isotopes of mesozoic-cenozoic granites in Qinghai-Tibetan plateau

International Nuclear Information System (INIS)

Qiu Ruizhao; Deng Jinfu; Zhou Su; Xiao Qinghui; Cai Zhiyong

2003-01-01

Mesozoic-Cenozoic magmatic activities were intensive in Qinghai-Tibetan plateau. Nd-Sr isotopic compositions of representative granitic plutons in western Qinghai-Tibetan plateau are reported in this paper. Combining with past isotopic data, which has reported in eastern Qinghai-Tibetan plateau, Sr-Nd isotopic compositions and material source and genesis of Mesozoic and Cenozoic granites in Qinghai-Tibetan plateau have been studied. The research result indicates there are three types of granite existing in Qinghai-Tibetan plateau, the granites of Late stage of Yanshan Period which distributing on north and south boundary of Gandes block (namely in north and south granitic belts of Dangdes) and cause of oceanic crust subduction, have ( 87 Sr/ 86 Sr)i of 0.7041-0.7064, ε (Nd) t of +2.5 - +5.7 and TDM age of 312-562 Ma, positive ε Nd, low ( 87 Sr/ 86 Sr)i ratio and young Nd model ages suggest relatively high contents of mantle-derived components in their sources, and this type granite might melt from subduction oceanic crust. The granites occurred intra-Gangdes block which were caused by collision of continent and post-collision, have ( 87 Sr/ 86 Sr)i of 0.706-0.719, ε (Nd) t of -5.3 - -8.3 and TDM age of 1323-1496 Ma, negative ε Nd, relative high ( 87 Sr/ 86 Sr)i ratio with an mid-Proterozoic Nd model ages, suggest granite has the mixing genesis of mantle-derived components and old crustal components in their sources. With relatively small variation range in ε (Nd) t and TDM age, it might imply granitic isotopic source in Gandes block to keep relative homogenization in long period. The granites in Himalayan block which there is not oceanic material to join in melting and to cause of intra-continental subduction, has most ( 87 Sr/ 86 Sr)i ratio more than 0.720, ε (Nd) t of -10.3 - -16.3 and TDM age of 1792-2206 Ma, high ( 87 Sr/ 86 Sr)i ratio, low negative ε (Nd)t with old Nd isotopic model ages and consistent with the Sr, Nd isotopic compositions of basement

A Cretaceous eutriconodont and integument evolution in early mammals.

Science.gov (United States)

Martin, Thomas; Marugán-Lobón, Jesús; Vullo, Romain; Martín-Abad, Hugo; Luo, Zhe-Xi; Buscalioni, Angela D

2015-10-15

The Mesozoic era (252-66 million years ago), known as the domain of dinosaurs, witnessed a remarkable ecomorphological diversity of early mammals. The key mammalian characteristics originated during this period and were prerequisite for their evolutionary success after extinction of the non-avian dinosaurs 66 million years ago. Many ecomorphotypes familiar to modern mammal fauna evolved independently early in mammalian evolutionary history. Here we report a 125-million-year-old eutriconodontan mammal from Spain with extraordinary preservation of skin and pelage that extends the record of key mammalian integumentary features into the Mesozoic era. The new mammalian specimen exhibits such typical mammalian features as pelage, mane, pinna, and a variety of skin structures: keratinous dermal scutes, protospines composed of hair-like tubules, and compound follicles with primary and secondary hairs. The skin structures of this new Mesozoic mammal encompass the same combination of integumentary features as those evolved independently in other crown Mammalia, with similarly broad structural variations as in extant mammals. Soft tissues in the thorax and abdomen (alveolar lungs and liver) suggest the presence of a muscular diaphragm. The eutriconodont has molariform tooth replacement, ossified Meckel's cartilage of the middle ear, and specialized xenarthrous articulations of posterior dorsal vertebrae, convergent with extant xenarthran mammals, which strengthened the vertebral column for locomotion.

Geological exploration of Angola from Sumbe to Namibe: A review at the frontier between geology, natural resources and the history of geology

Science.gov (United States)

Masse, Pierre; Laurent, Olivier

2016-01-01

This paper provides a review of the Geological exploration of the Angola Coast (from Sumbe to Namibe) from pioneer's first geological descriptions and mining inventory to the most recent publications supported by the oil industry. We focus our attention on the following periods: 1875-1890 (Paul Choffat's work, mainly), 1910-1949 (first maps at country scale), 1949-1974 (detailed mapping of the Kwanza-Namibe coastal series), 1975-2000, with the editing of the last version of the Angola geological map at 1:1 million scale and the progressive completion of previous works. Since 2000, there is a renewal in geological fieldwork publications on the area mainly due to the work of university teams. This review paper thus stands at the frontier between geology, natural resources and the history of geology. It shows how geological knowledge has progressed in time, fueled by economic and scientific reasons.

The Geologic Nitrogen Cycle

Science.gov (United States)

Johnson, B. W.; Goldblatt, C.

2013-12-01

N2 is the dominant gas in Earth's atmosphere, and has been so through the majority of the planet's history. Originally thought to only be cycled in significant amounts through the biosphere, it is becoming increasingly clear that a large degree of geologic cycling can occur as well. N is present in crustal rocks at 10s to 100s of ppm and in the mantle at 1s to perhaps 10s of ppm. In light of new data, we present an Earth-system perspective of the modern N cycle, an updated N budget for the silicate Earth, and venture to explain the evolution of the N cycle over time. In an fashion similar to C, N has a fast, biologically mediated cycle and a slower cycle driven by plate tectonics. Bacteria fix N2 from the atmosphere into bioavailable forms. N is then cycled through the food chain, either by direct consumption of N-fixing bacteria, as NH4+ (the primary waste form), or NO3- (the most common inorganic species in the modern ocean). Some organic material settles as sediment on the ocean floor. In anoxic sediments, NH4+ dominates; due to similar ionic radii, it can readily substitute for K+ in mineral lattices, both in sedimentary rocks and in oceanic lithosphere. Once it enters a subduction zone, N may either be volatilized and returned to the atmosphere at arc volcanoes as N2 or N2O, sequestered into intrusive igneous rocks (as NH4+?), or subducted deep into the mantle, likely as NH4+. Mounting evidence indicates that a significant amount of N may be sequestered into the solid Earth, where it may remain for long periods (100s m.y.) before being returned to the atmosphere/biosphere by volcanism or weathering. The magnitude fluxes into the solid Earth and size of geologic N reservoirs are poorly constrained. The size of the N reservoirs contained in the solid Earth directly affects the evolution of Earth's atmosphere. It is possible that N now sequestered in the solid Earth was once in the atmosphere, which would have resulted in a higher atmospheric pressure, and

Post-Palaeozoic evolution of weathered landsurfaces in Uganda by tectonically controlled deep weathering and stripping

Science.gov (United States)

Taylor, R. G.; Howard, K. W. F.

1998-11-01

A model for the evolution of weathered landsurfaces in Uganda is developed using available geotectonic, climatic, sedimentological and chronological data. The model demonstrates the pivotal role of tectonic uplift in inducing cycles of stripping, and tectonic quiescence for cycles of deep weathering. It is able to account for the development of key landforms, such as inselbergs and duricrust-capped plateaux, which previous hypotheses of landscape evolution that are based on climatic or eustatic controls are unable to explain. Development of the Ugandan landscape is traced back to the Permian. Following late Palaeozoic glaciation, a trend towards warmer and more humid climates through the Mesozoic enabled deep weathering of the Jurassic/mid-Cretaceous surface in Uganda during a period of prolonged tectonic quiescence. Uplift associated with the opening South Atlantic Ocean terminated this cycle and instigated a cycle of stripping between the mid-Cretaceous and early Miocene. Deep weathering on the succeeding Miocene to recent (African) surface has occurred from Miocene to present but has been interrupted in the areas adjacent to the western rift where development of a new drainage base level has prompted cycles of stripping in the Miocene and Pleistocene.

Quantifying uncertainty of geological 3D layer models, constructed with a-priori geological expertise

NARCIS (Netherlands)

Gunnink, J.J.; Maljers, D.; Hummelman, J.

2010-01-01

Uncertainty quantification of geological models that are constructed with additional geological expert-knowledge is not straightforward. To construct sound geological 3D layer models we use a lot of additional knowledge, with an uncertainty that is hard to quantify. Examples of geological expert

How semantics can inform the geological mapping process and support intelligent queries

Science.gov (United States)

Lombardo, Vincenzo; Piana, Fabrizio; Mimmo, Dario

2017-04-01

The geologic mapping process requires the organization of data according to the general knowledge about the objects, namely the geologic units, and to the objectives of a graphic representation of such objects in a map, following an established model of geotectonic evolution. Semantics can greatly help such a process in two concerns: the provision of a terminological base to name and classify the objects of the map; on the other, the implementation of a machine-readable encoding of the geologic knowledge base supports the application of reasoning mechanisms and the derivation of novel properties and relations about the objects of the map. The OntoGeonous initiative has built a terminological base of geological knowledge in a machine-readable format, following the Semantic Web tenets and the Linked Data paradigm. The major knowledge sources of the OntoGeonous initiative are GeoScience Markup Language schemata and vocabularies (through its last version, GeoSciML 4, 2015, published by the IUGS CGI Commission) and the INSPIRE "Data Specification on Geology" directives (an operative simplification of GeoSciML, published by INSPIRE Thematic Working Group Geology of the European Commission). The Linked Data paradigm has been exploited by linking (without replicating, to avoid inconsistencies) the already existing machine-readable encoding for some specific domains, such as the lithology domain (vocabulary Simple Lithology) and the geochronologic time scale (ontology "gts"). Finally, for the upper level knowledge, shared across several geologic domains, we have resorted to NASA SWEET ontology. The OntoGeonous initiative has also produced a wiki that explains how the geologic knowledge has been encoded from shared geoscience vocabularies (https://www.di.unito.it/wikigeo/). In particular, the sections dedicated to axiomatization will support the construction of an appropriate data base schema that can be then filled with the objects of the map. This contribution will discuss

Geologic Map of the MTM -30262 and -30267 Quadrangles, Hadriaca Patera Region of Mars

Science.gov (United States)

Crown, David A.; Greeley, Ronald

2007-01-01

Introduction Mars Transverse Mercator (MTM) -30262 and -30267 quadrangles cover the summit region and east margin of Hadriaca Patera, one of the Martian volcanoes designated highland paterae. MTM -30262 quadrangle includes volcanic deposits from Hadriaca Patera and Tyrrhena Patera (summit northeast of map area) and floor deposits associated with the Dao and Niger Valles canyon systems (south of map area). MTM -30267 quadrangle is centered on the caldera of Hadriaca Patera. The highland paterae are among the oldest, central-vent volcanoes on Mars and exhibit evidence for explosive eruptions, which make a detailed study of their geology an important component in understanding the evolution of Martian volcanism. Photogeologic mapping at 1:500,000-scale from analysis of Viking Orbiter images complements volcanological studies of Hadriaca Patera, geologic investigations of the other highland paterae, and an analysis of the styles and evolution of volcanic activity east of Hellas Planitia in the ancient, cratered highlands of Mars. This photogeologic study is an extension of regional geologic mapping east of Hellas Planitia. The Martian highland paterae are low-relief, areally extensive volcanoes exhibiting central calderas and radial channels and ridges. Four of these volcanoes, Hadriaca, Tyrrhena, Amphitrites, and Peneus Paterae, are located in the ancient cratered terrains surrounding Hellas Planitia and are thought to be located on inferred impact basin rings or related fractures. Based on analyses of Mariner 9 images, Potter (1976), Peterson (1977), and King (1978) suggested that the highland paterae were shield volcanoes formed by eruptions of fluid lavas. Later studies noted morphologic similarities between the paterae and terrestrial ash shields and the lack of primary lava flow features on the flanks of the volcanoes. The degraded appearances of Hadriaca and Tyrrhena Paterae and the apparently easily eroded materials composing their low, broad shields further

Genetic and geological classification wetlands proposed. Application to the spanish wetlands included in the Ramsar convention; Propuesta de clasificacion genetico-geologica de humedales. Aplicacion a los humedales espanoles incluidos en el Convenio de Ramsar

Energy Technology Data Exchange (ETDEWEB)

Duran Valsero, J. J.; Garcia de Domingo, A.; Robledo Ardila, P.

2009-07-01

The classification represents the first step in the research of the wetlands. There are several types of classifications established according different criteria: geographic, genetic, geologic, functional, hydric, biologic and others. In this work we considered the genetic and geologic classifications criteria are the more suitable because the criteria used are very concrete, descriptive and its application should be easier to put into practice. Every group established in this type of classification determines the develop naturals conditions allowing us to establish the evolution guidelines and same main management lines. The criteria used to develop this classification have been fundamentally: geologic, geomorphologic, tectonics, stratigraphic, and hydrogeologic because these determine greatly the physical wetland characteristics (geometric parameters, hydric nourishment system, hydrochemical characteristics and others). The general characteristics, guidelines behavior of the wetland, and the early evolution of every group of wetland could be essentials to detect and identified those actuations modifying the natural evolution in each concrete wetland. In this work we are applying these classification criteria to the Spanish wetlands included in the Ramsar Convention (until February 2006), defining twelve types of basic wetlands according the geologic and genetic characteristics. (Author) 19 refs.

Geologic map of the Tuba City 30' x 60' quadrangle, Coconino County, northern Arizona

Science.gov (United States)

Billingsley, George H.; Stoffer, Philip W.; Priest, Susan S.

2012-01-01

The Tuba City 30’ x 60’ quadrangle encompasses approximately 5,018 km² (1,920 mi²) within Coconino County, northern Arizona. It is characterized by nearly flat lying to gently dipping sequences of Paleozoic and Mesozoic strata that overly tilted Precambrian strata or metasedimentary and igneous rocks that are exposed at the bottom of Grand Canyon. The Paleozoic rock sequences from Cambrian to Permian age are exposed in the walls of Grand Canyon, Marble Canyon, and Little Colorado River Gorge. Mesozoic sedimentary rocks are exposed in the eastern half of the quadrangle where resistant sandstone units form cliffs, escarpments, mesas, and local plateaus. A few Miocene volcanic dikes intrude Mesozoic rocks southwest, northwest, and northeast of Tuba City, and Pleistocene volcanic rocks representing the northernmost extent of the San Francisco Volcanic Field are present at the south-central edge of the quadrangle. Quaternary deposits mantle much of the Mesozoic rocks in the eastern half of the quadrangle and are sparsely scattered in the western half. Principal folds are the north-south-trending, east-dipping Echo Cliffs Monocline and the East Kaibab Monocline. The East Kaibab Monocline elevates the Kaibab, Walhalla, and Coconino Plateaus and parts of Grand Canyon. Grand Canyon erosion has exposed the Butte Fault beneath the east Kaibab Monocline, providing a window into the structural complexity of monoclines in this part of the Colorado Plateau. Rocks of Permian and Triassic age form the surface bedrock of Marble Plateau and House Rock Valley between the East Kaibab and Echo Cliffs Monoclines. The Echo Cliffs Monocline forms a structural boundary between the Marble Plateau to the west and the Kaibito and Moenkopi Plateaus to the east. Jurassic rocks of the Kaibito and Moenkopi Plateaus are largely mantled by extensive eolian sand deposits. A small part of the northeast-dipping Red Lake Monocline is present in the northeast corner of the quadrangle. A broad and

Asteroids astronomical and geological bodies

CERN Document Server

Burbine, Thomas H

2016-01-01

Asteroid science is a fundamental topic in planetary science and is key to furthering our understanding of planetary formation and the evolution of the Solar System. Ground-based observations and missions have provided a wealth of new data in recent years, and forthcoming missions promise further exciting results. This accessible book presents a comprehensive introduction to asteroid science, summarising the astronomical and geological characteristics of asteroids. The interdisciplinary nature of asteroid science is reflected in the broad range of topics covered, including asteroid and meteorite classification, chemical and physical properties of asteroids, observational techniques, cratering, and the discovery of asteroids and how they are named. Other chapters discuss past, present and future space missions and the threat that these bodies pose for Earth. Based on an upper-level course on asteroids and meteorites taught by the author, this book is ideal for students, researchers and professional scientists ...

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution: Introduction. Ph.D. Thesis

Science.gov (United States)

Leake, M. A.

1982-01-01

The relative ages of various geologic units and structures place tight constraints on the origin of the Moon and the planet Mercury, and thus provide a better understanding of the geologic histories of these bodies. Crater statistics, a reexamination of lunar geologic maps, and the compilation of a geologic map of a quarter of Mercury's surface based on plains units dated relative to crater degradation classes were used to determine relative ages. This provided the basis for deducing the origin of intercrater plains and their role in terrestrial planet evolution.

Tectonic and climatic considerations for deep geological disposal of radioactive waste: A UK perspective.

Science.gov (United States)

McEvoy, F M; Schofield, D I; Shaw, R P; Norris, S

2016-11-15

Identifying and evaluating the factors that might impact on the long-term integrity of a deep Geological Disposal Facility (GDF) and its surrounding geological and surface environment is central to developing a safety case for underground disposal of radioactive waste. The geological environment should be relatively stable and its behaviour adequately predictable so that scientifically sound evaluations of the long-term radiological safety of a GDF can be made. In considering this, it is necessary to take into account natural processes that could affect a GDF or modify its geological environment up to 1millionyears into the future. Key processes considered in this paper include those which result from plate tectonics, such as seismicity and volcanism, as well as climate-related processes, such as erosion, uplift and the effects of glaciation. Understanding the inherent variability of process rates, critical thresholds and likely potential influence of unpredictable perturbations represent significant challenges to predicting the natural environment. From a plate-tectonic perspective, a one million year time frame represents a very short segment of geological time and is largely below the current resolution of observation of past processes. Similarly, predicting climate system evolution on such time-scales, particularly beyond 200ka AP is highly uncertain, relying on estimating the extremes within which climate and related processes may vary with reasonable confidence. The paper highlights some of the challenges facing a deep geological disposal program in the UK to review understanding of the natural changes that may affect siting and design of a GDF. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Geological heritage of Morocco

International Nuclear Information System (INIS)

Elhadi, H.; Tahiri, A.

2012-01-01

Full text: The soil and subsoil of Morocco are rich in geological phenomena that bear the imprint of a history that goes back in time more than 2000 million years. Very many sites geologically remarkable exposed in accessible outcrops, with good quality remain unknown to the general public and therefore deserve to be vulgarized. It is a memory to acquaint to the present generations but also to preserve for future generations. In total, a rich geological heritage in many ways: Varied landscapes, international stratotypes, various geological structures, varied rocks, mineral associations, a huge procession of fossiles, remnants of oceanic crust (ophiolites) among oldests ones in the world (800my), etc... For this geological heritage, an approach of an overall inventory is needed, both regionally and nationally, taking into account all the skills of the earth sciences. This will put the item on the natural (geological) potentialities as a lever for sustainable regional development. For this, it is necessary to implement a strategy of ''geoconservation'' for the preservation and assessment of the geological heritage.

Geology of the north end of the Salt Valley Anticline, Grand County, Utah

Science.gov (United States)

Gard, Leonard Meade

1976-01-01

This report describes the geology and hydrology of a portion of the Salt Valley anticline lying north of Moab, Utah, that is being studied as a potential site for underground storage of nuclear waste in salt. Selection of this area was based on recommendations made in an earlier appraisal of the potential of Paradox basin salt deposits for such use. Part of sec. 5, T. 23 S., R. 20 E. has been selected as a site for subsurface investigation as a potential repository for radioactive waste. This site has easy access to transportation, is on public land, is isolated from human habitation, is not visible from Arches National Park, and the salt body lies within about 800 feet (244 m) of the surface. Further exploration should include investigation of possible ground water in the caprock and physical exploration of the salt body to identify a thick bed of salt for use as a storage zone that can be isolated from the shaly interbeds that possibly contain quantities of hydrocarbons. Salt Valley anticline, a northwest-trending diapiric structure, consists of Mesozoic sedimentary rocks arched over a thick core of salt of the Paradox Member of the Middle Pennsylvanian Hermosa Formation. Salt began to migrate to form and/or develop this structure shortly after it was deposited, probably in response to faulting. This migration caused upwelling of the salt creating a linear positive area. This positive area, in turn, caused increased deposition of sediments in adjacent areas which further enhanced salt migration. Not until late Jurassic time had flowage of the salt slowed sufficiently to allow sediments of the Morrison and younger formations to be deposited across the salt welt. A thick cap of insoluble residue was formed on top of the salt diapir as a result of salt dissolution through time. The crest of the anticline is breached; it collapsed in two stages during the Tertiary Period. The first stage was graben collapse during the early Tertiary; the second stage occurred after

3D Geological Mapping - uncovering the subsurface to increase environmental understanding

Science.gov (United States)

Kessler, H.; Mathers, S.; Peach, D.

2012-12-01

Geological understanding is required for many disciplines studying natural processes from hydrology to landscape evolution. The subsurface structure of rocks and soils and their properties occupies three-dimensional (3D) space and geological processes operate in time. Traditionally geologists have captured their spatial and temporal knowledge in 2 dimensional maps and cross-sections and through narrative, because paper maps and later two dimensional geographical information systems (GIS) were the only tools available to them. Another major constraint on using more explicit and numerical systems to express geological knowledge is the fact that a geologist only ever observes and measures a fraction of the system they study. Only on rare occasions does the geologist have access to enough real data to generate meaningful predictions of the subsurface without the input of conceptual understanding developed from and knowledge of the geological processes responsible for the deposition, emplacement and diagenesis of the rocks. This in turn has led to geology becoming an increasingly marginalised science as other disciplines have embraced the digital world and have increasingly turned to implicit numerical modelling to understand environmental processes and interactions. Recent developments in geoscience methodology and technology have gone some way to overcoming these barriers and geologists across the world are beginning to routinely capture their knowledge and combine it with all available subsurface data (of often highly varying spatial distribution and quality) to create regional and national geological three dimensional geological maps. This is re-defining the way geologists interact with other science disciplines, as their concepts and knowledge are now expressed in an explicit form that can be used downstream to design process models structure. For example, groundwater modellers can refine their understanding of groundwater flow in three dimensions or even directly

The JAERI program for development of safety assessment models and acquisition of data needed for assessment of geological disposal of high-level radioactive wastes

International Nuclear Information System (INIS)

Matsuzuru, H.

1991-01-01

The JAERI is conducting R and D program for the development of safety assessment methodologies and the acquisition of data needed for the assessment of geologic disposal of high-level radioactive wastes, aiming at the elucidation of feasibility of geologic disposal in Japan. The paper describes current R and D activities to develop interim versions of both a deterministic and a probabilistic methodologies based on a normal evolution scenario, to collect data concerning engineered barriers and geologic media through field and laboratory experiments, and to validate the models used in the methodologies. 2 figs., 2 refs

Geological Services Laboratory

Data.gov (United States)

Federal Laboratory Consortium — Researchers use computed tomography (CT) scanners at NETL’s Geological Services Laboratory in Morgantown, WV, to peer into geologic core samples to determine how...

Geology of Mars

International Nuclear Information System (INIS)

Soderblom, L.A.

1988-01-01

The geology of Mars and the results of the Mariner 4, 6/7, and 9 missions and the Viking mission are reviewed. The Mars chronology and geologic modification are examined, including chronological models for the inactive planet, the active planet, and crater flux. The importance of surface materials is discussed and a multispectral map of Mars is presented. Suggestions are given for further studies of the geology of Mars using the Viking data. 5 references

Geochemical investigation of groundwater in the Tono area, Japan. Chemical characteristics and groundwater evolution

International Nuclear Information System (INIS)

Iwatsuki, Teruki; Hama, Katsuhiro; Yoshida, Hidekazu

1997-01-01

Geochemical investigations form an important part of the R and D program at the Tono study site, central Japan. Detailed geological structure and groundwater chemistry have been studied to understand the geochemical environment in the sedimentary and crystalline rocks distributed in this area. The chemical evolution of the groundwater in the sedimentary rocks is characterized with the variation in Na + , Ca 2+ and HCO 3 - concentrations, and ion exchange and dissolution of calcite are dominant reactions in the evolution of groundwater. Geological investigation shows that a fracture system of crystalline rock can be classified into:intact zone, moderately fractured zone and intensely fractured zone, according to the frequency and the width of fractures and fractured zones. The groundwater in the intact and fractured zones of crystalline rock are characterized by Na + -Ca 2+ -HCO 3 - or Na + -HCO 3 - dominated water, and Na + -Ca 2+ -Fe 2+ -HCO 3 - dominated water. The chemical evolution of groundwater is, generally, controlled by water-rock interaction between plagioclase, iron minerals and groundwater. The groundwater at depth of G.L.-186m in the crystalline rock at the Tono area is characterized by the mixture between the oxidized surface water and the reduced groundwater. The investigation based on correlation between geological structures and groundwater chemistry can be applied to understand the geochemical environment in deep crystalline rock, and will support the development of a realistic hydrogeochemical model. (author)

History of geological disposal concept (3). Implementation phase of geological disposal (2000 upward)

International Nuclear Information System (INIS)

Masuda, Sumio; Sakuma, Hideki; Umeki, Hiroyuki

2015-01-01

Important standards and concept about geological disposal have been arranged as an international common base and are being generalized. The authors overview the concept of geological disposal, and would like this paper to help arouse broad discussions for promoting the implementation plan of geological disposal projects in the future. In recent years, the scientific and technological rationality of geological disposal has been recognized internationally. With the addition of discussions from social viewpoints such as ethics, economy, etc., geological disposal projects are in the stage of starting after establishment of social consensus. As an international common base, the following consolidated and systematized items have been presented as indispensable elements in promoting business projects: (1) step-by-step approach, (2) safety case, (3) reversibility and recovery potential, and (4) trust building and communications. This paper outlines the contents of the following cases, where international common base was reflected on the geological disposal projects in Japan: (1) final disposal method and safety regulations, and (2) impact of the Great East Japan Earthquake and Fukushima Daiichi Nuclear Power Station accident on geological disposal plan. (A.O.)

Evolution of the basalts from three back-arc basins of southwest Pacific

Digital Repository Service at National Institute of Oceanography (India)

Mudholkar, A.V.; Paropkari, A.L.

London: Blackie, pp 63}93 Parson LM, Pearce JA, Murton BJ, Hodkinson RA, and RRS Charles Darwin Scienti"c Party (1990) Role of ridge jumps and ridge propagation in the tectonic evolution of the Lau back-arc basin, southwest Paci"c. Geology, 18:470}473 Per...

Conduct of Geologic Field Work During Planetary Exploration: Why Geology Matters

Science.gov (United States)

Eppler, Dean B.

2010-01-01

The science of field geology is the investigative process of determining the distribution of rock units and structures on a planet fs surface, and it is the first-order data set that informs all subsequent studies of a planet, such as geochemistry, geochronology, geophysics, or remote sensing. For future missions to the Moon and Mars, the surface systems deployed must support the conduct of field geology if these endeavors are to be scientifically useful. This lecture discussed what field geology is all about.why it is important, how it is done, how conducting field geology informs many other sciences, and how it affects the design of surface systems and the implementation of operations in the future.

Geology's Impact on Culture

Science.gov (United States)

Pizzorusso, Ann

2017-04-01

Most people consider geology boring, static and difficult. The fields of astronomy and physics have "rebranded" themselves with exciting programs formatted so as to be readily understandable to the general public. The same thing can be done for geology. My research on geology's influence on other disciplines has resulted in a book, Tweeting da Vinci, in which I was able to show how geology affected Italy's art, architecture, medicine, religion, literature, engineering and just about everything else. The reaction to the book and my lectures by both students and the general public has been very positive, including four gold medals, with reviews and comments indicating that they never knew geology could be so exciting. The book is very user friendly, packed with facts, full-color photos, paintings, sketches and illustrations. Complex aspects of geology are presented in an easily understandable style. Widely diverse topics—such as gemology, folk remedies, grottoes, painting, literature, physics and religion—are stitched together using geology as a thread. Quoting everyone from Pliny the Elder to NASA physicist Friedemann Freund, the work is solidly backed scholarship that reads as easily as a summer novel. The book can be used in classes such as physics, chemistry, literature, art history, medicine, Classical Studies, Latin, Greek and Italian. By incorporating a "geologic perspective" in these courses, it can be perceived as a more "all encompassing" discipline and encourage more students to study it. The lectures I have given on college campuses have resulted in students seeing their own majors from a different perspective and some have even signed up for introductory geology courses. One college organized summer course to the Bay of Naples based on the book. We followed the geology as well as the culture of the area and the students were profoundly moved. To encourage dialog, the book is linked to Facebook, Twitter and Instagram. This has enabled followers from

Isotopic and geochemical evolution of ground and surface waters in a karst dominated geological setting: a case study from Belize, Central America

International Nuclear Information System (INIS)

Marfia, A.M.; Krishnamurthy, R.V.; Atekwana, E.A.; Panton, W.F.

2004-01-01

Analysis of stable isotopes and major ions in groundwater and surface waters in Belize, Central America was carried out to identify processes that may affect drinking water quality. Belize has a subtropical rainforest/savannah climate with a varied landscape composed predominantly of carbonate rocks and clastic sediments. Stable oxygen (δ 18 O) and hydrogen (δD) isotope ratios for surface and groundwater have a similar range and show high d-excess (10-40.8%o). The high d-excess in water samples suggest secondary continental vapor flux mixing with incoming vapor from the Caribbean Sea. Model calculations indicate that moisture derived from continental evaporation contributes 13% to overhead vapor load. In surface and groundwater, concentrations of dissolved inorganic carbon (DIC) ranged from 5.4 to 112.9 mg C/l and δ 13 C DIC ranged from -7.4 to -17.4%o. SO 4 2 , Ca 2+ and Mg 2+ in the water samples ranged from 2-163, 2-6593 and 2-90 mg/l, respectively. The DIC and δ 13 C DIC indicate both open and closed system carbonate evolution. Combined δ 13 C DIC and Ca 2+ , Mg 2+ , and SO 4 2- suggest additional groundwater evolution by gypsum dissolution and calcite precipitation. The high SO 4 2- content of some water samples indicates regional geologic control on water quality. Similarity in the range of δ 18 O, δD and δ 13 C DIC for surface waters and groundwater used for drinking water supply is probably due to high hydraulic conductivities of the karstic aquifers. The results of this study indicate rapid recharge of groundwater aquifers, groundwater influence on surface water chemistry and the potential of surface water to impact groundwater quality and vise versa

Environmental geology and hydrology

Science.gov (United States)

Nakić, Zoran; Mileusnić, Marta; Pavlić, Krešimir; Kovač, Zoran

2017-10-01

Environmental geology is scientific discipline dealing with the interactions between humans and the geologic environment. Many natural hazards, which have great impact on humans and their environment, are caused by geological settings. On the other hand, human activities have great impact on the physical environment, especially in the last decades due to dramatic human population growth. Natural disasters often hit densely populated areas causing tremendous death toll and material damage. Demand for resources enhanced remarkably, as well as waste production. Exploitation of mineral resources deteriorate huge areas of land, produce enormous mine waste and pollute soil, water and air. Environmental geology is a broad discipline and only selected themes will be presented in the following subchapters: (1) floods as natural hazard, (2) water as geological resource and (3) the mining and mineral processing as types of human activities dealing with geological materials that affect the environment and human health.

The determination of initial ratio of strontium isotope in rocks and its geological application

International Nuclear Information System (INIS)

Ying Junlong; Zhao Puyun; Lin Xiulan

1989-04-01

The method to determine the initial ratio of strontium isotopes existed in rocks of poor rubidium and rich strontium and main carrier minerals is introduced. The initial ratio obtained from this method is equivalent to that acquired by Rb-Sr isochrone. Based on this result, information on regional rock genesis and mineralization regularities can be provided. It has great significance in the research on activities of ancient continental margin and material sources as well as their evolution. The migration of rock, and ore-forming materials, matallogenetic mechanism and its distribution in the space and time evolution are studied by using these data. In conclusion, the determination of strontium isotopes has broad prospects in the geological research

Radar, geologic, airborne gamma ray and Landsat TM digital data integration for geological mapping of the Estrela granite complex (Para State)

International Nuclear Information System (INIS)

Cunha, Edson Ricardo Soares Pereira da

2002-01-01

This work is focused on the geotectonic context of the Carajas Mineral Province, Amazon Craton, which represents the most important Brazilian Mineral Province and hosts iron, cooper, gold, manganese and nickel deposits. At the end of Archean age, during the techno-metamorphic evolution, moderated alkaline granitoids were generated, such as, Estrela Granite Complex (EGC). This work has used digital integration products with the purpose of study the granite suite, its host rock, and the surrounded area. The digital integrated data were gamma-ray and geological data with satellite images (SAR-SAREX e TM-Landsat). The geophysics data, originally in 32 bits and grid format, were interpolated and converted to 8 bits images. The geological data (facies map) was digitalized and converted to a raster format. The remote sensing images were geometrically corrected to guarantee an accuracy on the geological mapping. On the data processing phase, SAR images were digital integrated with gamma-ray data, TM-Landsat image and the raster facies map. The IHS transformation was used as the technique to integrate the multi-source data. On the photogeological interpretation, SAR data were extremely important to permit the extraction of the main tectonic lineaments which occur on the following directions: +/- N45W, +/- N70W, +/- NS, +/- N20E, +/- N45E e +/- N75E. This procedure was done both in analogic and automatic form, being the automatic process more useful to complement information in the extracting process. Among the digital products generated, SAR/GAMA products (uranium, thorium and total count) were the ones that give the most important contribution. The interpretation of the SAR/GAMA's products added to the field campaign have allowed to map the limits of units that occur in the region and four facies of the Estrela Granite Complex were detected. The origin of the granite suite might be related to a magmatic differentiation or to distinct intrusion pulses. The use of the

The Colorado Plateau Coring Project: A Continuous Cored Non-Marine Record of Early Mesozoic Environmental and Biotic Change

Science.gov (United States)

Irmis, Randall; Olsen, Paul; Geissman, John; Gehrels, George; Kent, Dennis; Mundil, Roland; Rasmussen, Cornelia; Giesler, Dominique; Schaller, Morgan; Kürschner, Wolfram; Parker, William; Buhedma, Hesham

2017-04-01

The early Mesozoic is a critical time in earth history that saw the origin of modern ecosystems set against the back-drop of mass extinction and sudden climate events in a greenhouse world. Non-marine sedimentary strata in western North America preserve a rich archive of low latitude terrestrial ecosystem and environmental change during this time. Unfortunately, frequent lateral facies changes, discontinuous outcrops, and a lack of robust geochronologic constraints make lithostratigraphic and chronostratigraphic correlation difficult, and thus prevent full integration of these paleoenvironmental and paleontologic data into a regional and global context. The Colorado Plateau Coring Project (CPCP) seeks to remedy this situation by recovering a continuous cored record of early Mesozoic sedimentary rocks from the Colorado Plateau of the western United States. CPCP Phase 1 was initiated in 2013, with NSF- and ICDP-funded drilling of Triassic units in Petrified Forest National Park, northern Arizona, U.S.A. This phase recovered a 520 m core (1A) from the northern part of the park, and a 240 m core (2B) from the southern end of the park, comprising the entire Lower-Middle Triassic Moenkopi Formation, and most of the Upper Triassic Chinle Formation. Since the conclusion of drilling, the cores have been CT scanned at the University of Texas - Austin, and split, imaged, and scanned (e.g., XRF, gamma, and magnetic susceptibility) at the University of Minnesota LacCore facility. Subsequently, at the Rutgers University Core Repository, core 1A was comprehensively sampled for paleomagnetism, zircon geochronology, petrography, palynology, and soil carbonate stable isotopes. LA-ICPMS U-Pb zircon analyses are largely complete, and CA-TIMS U-Pb zircon, paleomagnetic, petrographic, and stable isotope analyses are on-going. Initial results reveal numerous horizons with a high proportion of Late Triassic-aged primary volcanic zircons, the age of which appears to be a close

Geologic Time.

Science.gov (United States)

Newman, William L.

One of a series of general interest publications on science topics, the booklet provides those interested in geologic time with an introduction to the subject. Separate sections discuss the relative time scale, major divisions in geologic time, index fossils used as guides for telling the age of rocks, the atomic scale, and the age of the earth.…

Sedimentary Geology Context and Challenges for Cyberinfrastructure Data Management

Science.gov (United States)

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

2014-12-01

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

OneGeology-Europe: architecture, portal and web services to provide a European geological map

Science.gov (United States)

Tellez-Arenas, Agnès.; Serrano, Jean-Jacques; Tertre, François; Laxton, John

2010-05-01

OneGeology-Europe is a large ambitious project to make geological spatial data further known and accessible. The OneGeology-Europe project develops an integrated system of data to create and make accessible for the first time through the internet the geological map of the whole of Europe. The architecture implemented by the project is web services oriented, based on the OGC standards: the geological map is not a centralized database but is composed by several web services, each of them hosted by a European country involved in the project. Since geological data are elaborated differently from country to country, they are difficult to share. OneGeology-Europe, while providing more detailed and complete information, will foster even beyond the geological community an easier exchange of data within Europe and globally. This implies an important work regarding the harmonization of the data, both model and the content. OneGeology-Europe is characterised by the high technological capacity of the EU Member States, and has the final goal to achieve the harmonisation of European geological survey data according to common standards. As a direct consequence Europe will make a further step in terms of innovation and information dissemination, continuing to play a world leading role in the development of geosciences information. The scope of the common harmonized data model was defined primarily by the requirements of the geological map of Europe, but in addition users were consulted and the requirements of both INSPIRE and ‘high-resolution' geological maps were considered. The data model is based on GeoSciML, developed since 2006 by a group of Geological Surveys. The data providers involved in the project implemented a new component that allows the web services to deliver the geological map expressed into GeoSciML. In order to capture the information describing the geological units of the map of Europe the scope of the data model needs to include lithology; age; genesis and

Brief analysis on relationship between red beds and sandstone-type uranium ore-formation

International Nuclear Information System (INIS)

Ji Zengxian

2006-01-01

Red beds are sandy gravel beds deposited under the arid and hot climates and correspondent to the oxidation environment of continental basins. As an exogenetic epigenetic uranium deposit, the formation of the sandstone-type uranium deposit needs a large chronologic gap between the diagenesis and the subsequent uranium metallogenesis of the ore-hosting target layer with a sedimentary discontinuity and an alternative humid-arid climate. Red beds are the product of this time. The evolutionary times of red beds are in accordance with the formation of the sandstone-type uranium deposit. Both domestic and abroad researches indicate that each times evolution of a red bed might be associated with uranium ore-formation in one or more sandstone layers in the region. In China, red beds are developed in many geologic periods, but sandstone-type uranium mineralization occurs mostly in Mesozoic-Cenozoic. Taking five known sandstone-type uranium deposits as examples, the author makes a primary analysis on the relationship between red beds and the subsequent sandstone-type uranium mineralization. It is suggested that the deposition of red beds and sandstone-type uranium metallogenesis are of 'cogenesis and coexistence' and that the deposition of red beds and its evolutionary times can be regarded as the prerequisites to judge the potential of sandstone-type uranium mineralization in a Mesozoic-Cenozoic sedimentary basin. (authors)

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

Science.gov (United States)

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

2018-07-01

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

Glaciation and geosphere evolution - Greenland Analogue Project

International Nuclear Information System (INIS)

Hirschorn, S.; Vorauer, A.; Belfadhel, M.B.; Jensen, M.

2011-01-01

The deep geological repository concept for the long-term management of used nuclear fuel involves the containment and isolation of used nuclear fuel in a suitable geological formation. A key objective of the Canadian Nuclear Waste Management Organization (NWMO) geoscience technical research program is to advance the understanding of geosphere stability and its resilience to perturbations over time frames of relevance to a deep geological repository. Glaciation has been identified as the most probable and intense perturbation relevant to a deep geological repository associated with long-term climate change in northern latitudes. Given that the North American continent has been re-glaciated nine times over the past million years, it is strongly expected that a deep geological repository within a suitable crystalline or sedimentary rock formation in Canada will be subject to glaciation events associated with long-term climate change. As such, NWMO's geoscience research program has placed particular emphasis on investigations of the response of the geosphere to glaciations. As surface conditions change from present day conditions to periglacial, followed by ice-sheet cover of variable thickness and rapid glacial retreat, transient geochemical, hydraulic, mechanical and temperature conditions will be simultaneously imposed on groundwater systems. NWMO research activities related to glaciation events and their impacts on groundwater system evolution are being undertaken using a multi-disciplinary approach aimed at collecting multiple lines of evidence. These investigations include assessment of the: Impact of an ice sheet on groundwater composition at repository depth using the Greenland Ice Sheet as an analogue to future glaciations in North America; Expected physical and temporal surface boundary conditions related to potential future glaciation events by estimating the magnitude and time rate of change of ice sheet thickness, ground surface temperature and

Structure, stratigraphy, and petroleum geology of the Little Plain basin, northwestern Hungary

Science.gov (United States)

Mattick, R.E.; Teleki, P.G.; Phillips, R.L.; Clayton, J.L.; David, G.; Pogcsas, G.; Bardocz, B.; Simon, E.

1996-01-01

The basement of the Little Plain (Kisalfo??ld) basin is composed of two parts: an eastern part comprised of folded and overthrusted Triassic and Paleozoic rocks of the Pelso block (Transdanubian Central Range) compressed in the Early Cretaceous, and a western part consisting of stacked nappes of the Austroalpine zone of Paleozoic rocks, significantly metamorphosed during Cretaceous and later compression, overriding Jurassic oceanic rift-zone rocks of the Penninic zone. The evolution of the basin began in the late Karpatian-early Badenian (middle Miocene) when the eastern part of the basin began to open along conjugate sets of northeast- and northwest-trending normal faults. Neogene rocks in the study area, on the average, contain less than 0.5 wt. % total organic carbon (TOC) and, therefore, are not considered effective source rocks. Locally, however, where TOC values are as high as 3 wt. %, significant amounts of gas may have been generated and expelled. Although potential stratigraphic traps are numerous in the Neogene section, these potential traps must be downgraded because of the small amount of hydrocarbons discovered in structural traps to date. With the exception of the Cretaceous, the Mesozoic section has not been actively explored. Large anticlinal and overthrust structures involving pre-Cretaceous strata remain undrilled.

Homo Sapiens as Geological Agents

Science.gov (United States)

Holloway, T.; Bedsworth, L. W.; Caldeira, K.; Rosenzweig, C.; Kelley, G.; Rosenzweig, C.; Caldeira, K.; Bedsworth, L. W.; Holloway, T.; Purdy, J. S.; Vince, G.; Syvitski, J. A.; Bondre, N. R.; Kelly, J.; Vince, G.; Seto, K. C.; Steffen, W.; Oreskes, N.

2015-12-01

In the 18th and 19th centuries, earth scientists came to understand the magnitude and power of geological and geophysical processes. In comparison, the activities of humans seemed paltry if not insignificant. With the development of radiometric dating in the 20th century, scientists realized that human history was but a miniscule part of Earth history. Metaphors to this effect abounded, and filled textbooks: If Earth history were a 24-hour day, human history would not occupy even the final second. If Earth history were a yardstick, the human portion would not even be visible to the naked eye. Generations of scientists were taught that one of the principal contributions of geology, qua science, was the demonstration of our insignificance. The Anthropocene concept disrupts this. To affirms its existence is to insist that human activities compete in scale and significance with other Earth processes, and may threaten to overwhelm them. It also inverts our relation to normative claims. For more than a century earth scientists and evolutionary biologists insisted that their theories were descriptive and not normative—that there was no moral conclusion to be drawn from either planetary or human evolution. Now, we confront the suggestion that there is a moral component to our new paradigm: we can scarcely claim that humans are disrupting the climate, destroying biodiversity, and acidifying the oceans without implying that there is something troubling about these developments. Thus, the Anthropocene concept suggests both a radical redefinition of the scope of Earth science, and a radical reconsideration of the place of normative judgments in scientific work.

Lunar exploration: opening a window into the history and evolution of the inner Solar System.

Science.gov (United States)