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Sample records for early precambrian microfossils

  1. Remarkably preserved tephra from the 3430 Ma Strelley Pool Formation, Western Australia: Implications for the interpretation of Precambrian microfossils

    Science.gov (United States)

    Wacey, David; Saunders, Martin; Kong, Charlie

    2018-04-01

    SPF in the East Strelley greenstone belt. We find that the majority of previously illustrated microfossils from this greenstone belt possess multiple features that are consistent with a biological interpretation and are unlikely to be volcanogenic, but at least one previously illustrated specimen is here reinterpreted as volcanic in origin. The importance of this work is that it serves to highlight the common occurrence of volcanogenic microstructures resembling biological fossils (i.e. pseudo-fossils) in Archean environments that are habitable for life. Such structures have until now been largely overlooked in the assessment of putative Precambrian microfossils. Our data show that tephra-derived microstructures should be considered as a null hypothesis in future evaluations of potential signs of life on the early Earth, or on other planets.

  2. Identifying early Earth microfossils in unsilicified sediments

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    Javaux, Emmanuelle J.; Asael, Dan; Bekker, Andrey; Debaille, Vinciane; Derenne, Sylvie; Hofmann, Axel; Mattielli, Nadine; Poulton, Simon

    2013-04-01

    The search for life on the early Earth or beyond Earth requires the definition of biosignatures, or "indices of life". These traditionally include fossil molecules, isotopic fractionations, biosedimentary structures and morphological fossils interpreted as remnants of life preserved in rocks. This research focuses on traces of life preserved in unsilicified siliciclastic sediments. Indeed, these deposits preserve well sedimentary structures indicative of past aqueous environments and organic matter, including the original organic walls of microscopic organisms. They also do not form in hydrothermal conditions which may be source of abiotic organics. At our knowledge, the only reported occurrence of microfossils preserved in unsilicified Archean sediments is a population of large organic-walled vesicles discovered in shales and siltstones of the 3.2 Ga Moodies Group, South Africa. (Javaux et al, Nature 2010). These have been interpreted as microfossils based on petrographic and geochemical evidence for their endogenicity and syngeneity, their carbonaceous composition, cellular morphology and ultrastructure, occurrence in populations, taphonomic features of soft wall deformation, and the geological context plausible for life, as well as lack of abiotic explanation falsifying a biological origin. Demonstrating that carbonaceous objects from Archaean rocks are truly old and truly biological is the subject of considerable debate. Abiotic processes are known to produce organics and isotopic signatures similar to life. Spheroidal pseudofossils may form as self-assembling vesicles from abiotic CM, e.g. in prebiotic chemistry experiments (Shoztak et al, 2001), from meteoritic lipids (Deamer et al, 2006), or hydrothermal fluids (Akashi et al, 1996); by artifact of maceration; by migration of abiotic or biotic CM along microfractures (VanZuilen et al, 2007) or along mineral casts (Brasier et al, 2005), or around silica spheres formed in silica-saturated water (Jones and

  3. Fossil Microorganisms and Formation of Early Precambrian Weathering Profiles

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    Rozanov, A. Yu; Astafieva, M. M.; Vrevsky, A. B.; Alfimova, N. A.; Matrenichev, V. A.; Hoover, R. B.

    2009-01-01

    Weathering crusts are the only reliable evidences of the existence of continental conditions. Often they are the only source of information about exogenous processes and subsequently about conditions under which the development of the biosphere occurred. A complex of diverse fossil microorganisms was discovered as a result of Scanning Electron Microscope investigations. The chemical composition of the discovered fossils is identical to that of the host rocks and is represented by Si, Al, Fe, Ca and Mg. Probably, the microorganisms fixed in rocks played the role of catalyst. The decomposition of minerals comprising the rocks and their transformation into clayey (argillaceous) minerals, most likely occurred under the influence of microorganisms. And may be unique weathering crusts of Early Precambrian were formed due to interaction between specific composition of microorganism assemblage and conditions of hypergene transformations. So it is possible to speak about colonization of land by microbes already at that time and about existence of single raw from weathering crusts (Primitive soils) to real soils.

  4. Microfossils' diversity from the Proterozoic Taoudeni Basin, Mauritania

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    Beghin, Jérémie; Houzay, Jean-Pierre; Blanpied, Christian; Javaux, Emmanuelle

    2014-05-01

    palaeoecology (habitat diversity) of early eukaryotes, we are combining morphological, microchemical and ultrastructural studies of microfossils, with high-resolution palaeoenvironmental and palaeoredox characterization. References: Amard B. (1986) Microfossiles (Acritarches) du Protérozoïque supérieur dans les shales de la formation d'Atar (Mauritanie). Precambrian Research 31: 69-95. Blumenberg M, Thiel V, Riegel W, et al. (2012) Biomarkers of black shales formed by microbial mats, Late Mesoproterozoic (1.1 Ga) Taoudeni Basin, Mauritania. Precambrian Research 196-197: 113-127. Javaux EJ. (2011) Early eukaryotes in Precambrian oceans. Origins and Evolution of Life. An Astrobiological Perspective. Cambridge University Press, 414-449. Knoll AH, Javaux EJ, Hewitt D, et al. (2006) Eukaryotic organisms in Proterozoic oceans. Philosophical Transactions of the Royal Society B: Biological Sciences 361: 1023-1038.

  5. Cyanobacterial evolution during the Precambrian

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    Schirrmeister, Bettina E.; Sanchez-Baracaldo, Patricia; Wacey, David

    2016-07-01

    Life on Earth has existed for at least 3.5 billion years. Yet, relatively little is known of its evolution during the first two billion years, due to the scarceness and generally poor preservation of fossilized biological material. Cyanobacteria, formerly known as blue green algae were among the first crown Eubacteria to evolve and for more than 2.5 billion years they have strongly influenced Earth's biosphere. Being the only organism where oxygenic photosynthesis has originated, they have oxygenated Earth's atmosphere and hydrosphere, triggered the evolution of plants -being ancestral to chloroplasts- and enabled the evolution of complex life based on aerobic respiration. Having such a strong impact on early life, one might expect that the evolutionary success of this group may also have triggered further biosphere changes during early Earth history. However, very little is known about the early evolution of this phylum and ongoing debates about cyanobacterial fossils, biomarkers and molecular clock analyses highlight the difficulties in this field of research. Although phylogenomic analyses have provided promising glimpses into the early evolution of cyanobacteria, estimated divergence ages are often very uncertain, because of vague and insufficient tree-calibrations. Results of molecular clock analyses are intrinsically tied to these prior calibration points, hence improving calibrations will enable more precise divergence time estimations. Here we provide a review of previously described Precambrian microfossils, biomarkers and geochemical markers that inform upon the early evolution of cyanobacteria. Future research in micropalaeontology will require novel analyses and imaging techniques to improve taxonomic affiliation of many Precambrian microfossils. Consequently, a better understanding of early cyanobacterial evolution will not only allow for a more specific calibration of cyanobacterial and eubacterial phylogenies, but also provide new dates for the tree

  6. A morphogram for silica-witherite biomorphs and its application to microfossil identification in the early earth rock record.

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    Rouillard, J; García-Ruiz, J-M; Gong, J; van Zuilen, M A

    2018-05-01

    Archean hydrothermal environments formed a likely site for the origin and early evolution of life. These are also the settings, however, were complex abiologic structures can form. Low-temperature serpentinization of ultramafic crust can generate alkaline, silica-saturated fluids in which carbonate-silica crystalline aggregates with life-like morphologies can self-assemble. These "biomorphs" could have adsorbed hydrocarbons from Fischer-Tropsch type synthesis processes, leading to metamorphosed structures that resemble carbonaceous microfossils. Although this abiogenic process has been extensively cited in the literature and has generated important controversy, so far only one specific biomorph type with a filamentous shape has been discussed for the interpretation of Archean microfossils. It is therefore critical to precisely determine the full distribution in morphology and size of these biomorphs, and to study the range of plausible geochemical conditions under which these microstructures can form. Here, a set of witherite-silica biomorph synthesis experiments in silica-saturated solutions is presented, for a range of pH values (from 9 to 11.5) and barium ion concentrations (from 0.6 to 40 mmol/L BaCl 2 ). Under these varying conditions, a wide range of life-like structures is found, from fractal dendrites to complex shapes with continuous curvature. The size, spatial concentration, and morphology of the biomorphs are strongly controlled by environmental parameters, among which pH is the most important. This potentially limits the diversity of environments in which the growth of biomorphs could have occurred on Early Earth. Given the variety of the observed biomorph morphologies, our results show that the morphology of an individual microstructure is a poor criterion for biogenicity. However, biomorphs may be distinguished from actual populations of cellular microfossils by their wide, unimodal size distribution. Biomorphs grown by diffusion in silica gel can

  7. Geological nature of early Precambrian formations (considering the example of the Anabar shield)

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    Kuznetsov, A. A.

    The primordial nature of the catarchean-early Proterozoic crystalline formations making up the Anabar shield is analyzed on the basis of a variety of data, including Landsat observations. The shield is found to have a layered structure and a massively stratified rhythmic texture, consisting of geometrically regular layer-horizons, from several centimeters to several dozens of meters thick.

  8. Transitional changes in microfossil assemblages in the Japan Sea from the Late Pliocene to Early Pleistocene related to global climatic and local tectonic events

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    Itaki, Takuya

    2016-12-01

    Many micropaleontological studies based on data from on-land sections, oil wells, and deep-sea drilling cores have provided important information about environmental changes in the Japan Sea that are related to the global climate and the local tectonics of the Japanese Islands. Here, major changes in the microfossil assemblages during the Late Pliocene to Early Pleistocene are reviewed. Late Pliocene (3.5-2.7 Ma) surface-water assemblages were characterized mainly by cold-temperate planktonic flora and fauna (nannofossils, diatoms, radiolarians, and planktonic foraminifera), suggesting that nutrient-rich North Pacific surface waters entered the Japan Sea via northern straits. The common occurrence of Pacific-type deep-water radiolarians during this period also suggests that deep water from the North Pacific entered the Japan Sea via the northern straits, indicating a sill depth >500 m. A weak warm-water influence is recognized along the Japanese coast, suggesting a small inflow of warm water via a southern strait. Nannofossil and sublittoral ostracod assemblages record an abrupt cooling event at 2.75 Ma that correlates with the onset of the Northern Hemisphere glaciation. Subsequently, cold intermediate- and deep-water assemblages of ostracods and radiolarians increased in abundance, suggesting active ventilation and the formation of the Japan Sea Proper Water, associated with a strengthened winter monsoon. Pacific-type deep-water radiolarians also disappeared around 2.75 Ma, which is attributed to the intermittent occurrence of deep anoxic environments and limited migration from the North Pacific, resulting from the near-closure or shallowing of the northern strait by a eustatic fall in sea level and tectonic uplift of northeastern Japan. A notable reduction in primary productivity from 2.3 to 1.3 Ma also suggests that the nutrient supply from the North Pacific was restricted by the near-closure of the northern strait. An increase in the abundance of subtropical

  9. The evolutionary characteristics and study of uranium mineralization conditions of early precambrian basement and old granitoids in Northern Hebei province of China

    International Nuclear Information System (INIS)

    Xia Yuliang; Rong Jiashu; Lin Jinrong; Zheng Maogong; Wen Xiyuan

    1993-05-01

    Based on the systematic studies of petrology, geochemistry and isotope geochronology, the Early Precambrian metamorphic complex in Northern Hebei province of China can be divided into three different series, i.e. granulite series, khondalite series and amphibolitic-felsic rock series. The so called 'magmatic granitoids' in that area are actually some magmagranites with different ages and different geneses, and they are not formed by migmatization. Up to now, the discovered Huaian complex which was formed in 3.5 Ga ago is the oldest nuclear area in the northern margin of North-China Platform. The granulite series, khondalite series and amphibolitic-felsic rock series belong to Early Archaean (>3.0 +- 0.1 Ga), Middle Archaean (>2.7 +- 0.1 Ga) and Later Archaean (>2.4 +- 0.1 Ga) respectively. The geological time scale of the Early Precambrian for Northern Hebei Province has been built. According to the synthetic analyses of various factors there is no prospect of uranium mineralization in the ancient terrain. However, the Mesozoic volcanic basins covering over the Hercynian Period granites would be main goal for looking for large uranium deposits in north part in that area

  10. Oxygen isotope studies of early Precambrian granitic rocks from the Giants Range batholith, northeastern Minnesota, U.S.A.

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    Viswanathan, S.

    1974-01-01

    Oxygen isotope studies of granitic rocks from the 2.7 b.y.-old composite Giants Range batholith show that: (1) ??(O18)quartz values of 9 to 10 permil characterize relatively uncontaminated Lower Precambrian, magmatic granodiorites and granites; (2) granitic rocks thought to have formed by static granitization have ??(O18)quartz values that are 1 to 2 permil higher than magmatic granitic rocks; (3) satellite leucogranite bodies have values nearly identical to those of the main intrusive phases even where they transect O18-rich metasedimentary wall rocks; (4) oxygen isotopic interaction between the granitic melts and their O18-rich wall rocks was minimal; and (5) O18/O18 ratios of quartz grains in a metasomatic granite are largely inherited from the precursor rock, but during the progression - sedimentary parent ??? partially granitized parent ??? metasomatic granite ??? there is gradual decrease in ??(O18)quartz by 1 to 2 permil. ?? 1974.

  11. Evidence for marine microfossils from amber.

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    Girard, Vincent; Schmidt, Alexander R; Saint Martin, Simona; Struwe, Steffi; Perrichot, Vincent; Saint Martin, Jean-Paul; Grosheny, Danièle; Breton, Gérard; Néraudeau, Didier

    2008-11-11

    Amber usually contains inclusions of terrestrial and rarely limnetic organisms that were embedded in the places were they lived in the amber forests. Therefore, it has been supposed that amber could not have preserved marine organisms. Here, we report the discovery amber-preserved marine microfossils. Diverse marine diatoms as well as radiolarians, sponge spicules, a foraminifer, and a spine of a larval echinoderm were found in Late Albian and Early Cenomanian amber samples of southwestern France. The highly fossiliferous resin samples solidified approximately 100 million years ago on the floor of coastal mixed forests dominated by conifers. The amber forests of southwestern France grew directly along the coast of the Atlantic Ocean and were influenced by the nearby sea: shells and remnants of marine organisms were probably introduced by wind, spray, or high tide from the beach or the sea onto the resin flows.

  12. SHRIMP zircon dating and LA-ICPMS Hf analysis of early Precambrian rocks from drill holes into the basement beneath the Central Hebei Basin, North China Craton

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    Yusheng Wan

    2014-07-01

    Full Text Available The Central Hebei Basin (CHB is one of the largest sedimentary basins in the North China Craton, extending in a northeast–southwest direction with an area of >350 km2. We carried out SHRIMP zircon dating, Hf-in-zircon isotopic analysis and a whole-rock geochemical study on igneous and metasedimentary rocks recovered from drill holes that penetrated into the basement of the CHB. Two samples of gneissic granodiorite (XG1-1 and gneissic quartz diorite (J48-1 have magmatic ages of 2500 and 2496 Ma, respectively. Their zircons also record metamorphic ages of 2.41–2.51 and ∼2.5 Ga, respectively. Compared with the gneissic granodiorite, the gneissic quartz diorite has higher ΣREE contents and lower Eu/Eu* and (La/Ybn values. Two metasedimentary samples (MG1, H5 mainly contain ∼2.5 Ga detrital zircons as well as late Paleoproterozoic metamorphic grains. The zircons of different origins have εHf (2.5 Ga values and Hf crustal model ages ranging from 0 to 5 and 2.7 to 2.9 Ga, respectively. Therefore, ∼2.5 Ga magmatic and Paleoproterozoic metasedimentary rocks and late Neoarchean to early Paleoproterozoic and late Paleoproterozoic tectono-thermal events have been identified in the basement beneath the CHB. Based on regional comparisons, we conclude that the early Precambrian basement beneath the CHB is part of the North China Craton.

  13. Manganese, Metallogenium, and Martian Microfossils

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    Stein, L. Y.; Nealson, K. H.

    1999-01-01

    Manganese could easily be considered an abundant element in the Martian regolith, assuming that the composition of martian meteorites reflects the composition of the planet. Mineralogical analyses of 5 SNC meteorites have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.

  14. Uranium potentialities of precambrian from Goias State

    International Nuclear Information System (INIS)

    Danni, J.C.M.; Marini, O.J.; Faria, A. de; Dardenne, M.A.

    1983-01-01

    A chrono-stratigraphy synthesis of geological unities from Precambrian, with emphasis on characterization of its depositional region, tectonics and or lithology is presented. The main ideas relating to uranium metallogeny in precambrian ages referring to geologic situation in Goias is described. The uranium occurrence associated to precambrian unities from region and some interpretations for evaluation the potentialities of uranium metallotect are also cited. (C.G.C.)

  15. History and Evolution of Precambrian plate tectonics

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    Fischer, Ria; Gerya, Taras

    2014-05-01

    Plate tectonics is a global self-organising process driven by negative buoyancy at thermal boundary layers. Phanerozoic plate tectonics with its typical subduction and orogeny is relatively well understood and can be traced back in the geological records of the continents. Interpretations of geological, petrological and geochemical observations from Proterozoic and Archean orogenic belts however (e.g., Brown, 2006), suggest a different tectonic regime in the Precambrian. Due to higher radioactive heat production the Precambrian lithosphere shows lower internal strength and is strongly weakened by percolating melts. The fundamental difference between Precambrian and Phanerozoic tectonics is therefore the upper-mantle temperature, which determines the strength of the upper mantle (Brun, 2002) and the further tectonic history. 3D petrological-thermomechanical numerical modelling experiments of oceanic subduction at an active plate at different upper-mantle temperatures show these different subduction regimes. For upper-mantle temperatures 250 K above the present day value no subduction occurs any more. The whole lithosphere is delaminating and due to strong volcanism and formation of a thicker crust subduction is inhibited. This stage of 200-250 K higher upper mantle temperature which corresponds roughly to the early Archean (Abbott, 1994) is marked by strong volcanism due to sublithospheric decompression melting which leads to an equal thickness for both oceanic and continental plates. As a consequence subduction is inhibited, but a compressional setup instead will lead to orogeny between a continental or felsic terrain and an oceanic or mafic terrain as well as internal crustal convection. Small-scale convection with plume shaped cold downwellings also in the upper mantle is of increased importance compared to the large-scale subduction cycle observed for present temperature conditions. It is also observed that lithospheric downwellings may initiate subduction by

  16. A palaeomagnetic perspective of Precambrian tectonic styles

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    Schmidt, P. W.; Embleton, B. J. J.

    1986-01-01

    The considerable success derived from palaeomagnetic studies of Phanerozoic rocks with respect to the tectonic styles of continental drift and plate tectonics, etc., have not been repeated by the many palaeomagnetic studies of Precambrian rocks. There are 30 years of research with results covering the major continents for Precambrian times that overlap considerably yet there is no concensus. There is good evidence that the usual assumptions employed by palaeomagnetism are valid for the Precambrian. The exisence of magnetic reversals during the Precambrian, for instance, is difficult to explain except in terms of a geomagnetic field that was predominantly dipolar in nature. It is a small concession to extend this notion of the Precambrian geomagnetic field to include its alignment with the Earth's spin axis and the other virtues of an axial geocentric dipole that characterize the recent geomagnetic field. In terms of greenstone terranes it is obvious that tectonic models postulated to explain these observations are paramount in understanding Precambrian geology. What relevance the current geographical relationships of continents have with their Precambrian relationships remains a paradox, but it would seem that the ensialic model for the development of greenstone terranes is favored by the Precambrian palaeomagnetic data.

  17. Tectonic inheritance in the development of the Kivu - north Tanganyika rift segment of the East African Rift System: role of pre-existing structures of Precambrian to early Palaeozoic origin.

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    Delvaux, Damien; Fiama Bondo, Silvanos; Ganza Bamulezi, Gloire

    2017-04-01

    The present architecture of the junction between the Kivu rift basin and the north Tanganyika rift basin is that of a typical accommodation zone trough the Ruzizi depression. However, this structure appeared only late in the development of the Western branch of the East African Rift System and is the result of a strong control by pre-existing structures of Precambrian to early Palaeozoic origin. In the frame of a seismic hazard assessment of the Kivu rift region, we (Delvaux et al., 2016) constructed homogeneous geological, structural and neotectonic maps cross the five countries of this region, mapped the pre-rift, early rift and Late Quaternary faults and compiled the existing knowledge on thermal springs (assumed to be diagnostic of current tectonic activity along faults). We also produced also a new catalogue of historical and instrumental seismicity and defined the seismotectonic characteristics (stress field, depth of faulting) using published focal mechanism data. Rifting in this region started at about 11 Ma by initial doming and extensive fissural basaltic volcanism along normal faults sub-parallel to the axis of the future rift valley, as a consequence of the divergence between the Nubia and the Victoria plate. In a later stage, starting around 8-7 Ma, extension localized along a series of major border faults individualizing the subsiding tectonic basins from the uplifting rift shoulders, while lava evolved towards alkali basaltic composition until 2.6 Ma. During this stage, initial Kivu rift valley was extending linearly in a SSW direction, much further than its the actual termination at Bukavu, into the Mwenga-Kamituga graben, up to Namoya. The SW extremity of this graben was linked via a long oblique transfer zone to the central part of Lake Tanganyika, itself reactivating an older ductile-brittle shear zone. In the late Quaternary-early Holocene, volcanism migrated towards the center of the basin, with the development of the Virunga volcanic massif

  18. Reproductive cyst and operculum formation in the Cambrian-Ordovician galeate-plexus microfossils

    DEFF Research Database (Denmark)

    Agic, Heda; Moczydlowska, Malgorzata; Canfield, Donald Eugene

    2016-01-01

    Unicellular organic-walled microfossils from the Cambrian-Ordovician transition in Estonia (ca. 490-480million years ago) exhibit rare characters reflecting their function as reproductive algal cysts. The studied assemblages record the evolutionary history of phytoplankton in the early Palaeozoic...... alga Acetabularia (Chlorophyta), which possesses an intrinsic lid-forming apparatus used during the organism's reproductive stage. Based on the observations on the fossil material and studies on the Acetabularia lid formation, we propose a model of operculum formation in the galeate plexus micro-organisms...

  19. Compaction of microfossil and clay-rich chalk sediments

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2001-01-01

    The aim of this study was to evaluate the role of microfossils and clay in the compaction of chalk facies sediments. To meet this aim, chalk sediments with varying micro texture were studied. The sediments have been tested uniaxially confined in a stainless-steel compaction cell. The sediments are......: 1) Pure carbonate chalk with mudstone texture from Stevns Klint (Denmark), 2) Relatively pure chalk sediments with varying content of microfossils from the Ontong Java Plateau (Western Pacific), 3) Clay-rich chalk and mixed sediments from the Caribbean. The tested samples were characterised...

  20. Simulating Precambrian banded iron formation diagenesis

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    Posth, Nicole R.; K??hler, Inga; D. Swanner, Elizabeth

    2013-01-01

    Post-depositional diagenetic alteration makes the accurate interpretation of key precipitation processes in ancient sediments, such as Precambrian banded iron formations (BIFs), difficult. While microorganisms are proposed as key contributors to BIF deposition, the diagenetic transformation...

  1. Age determination of Precambrian rocks from Greenland: past and present

    International Nuclear Information System (INIS)

    Karlsbeek, F.

    1997-01-01

    For Precambrian rocks as well as for younger igneous intrusions, precise ages can only be obtained by isotopic analysis of minerals or rocks. Isotopic (radiometric) age determination of Greenland rocks began in the early 1960s and has continued since with gradually improving methods. In this contribution, the development of geochronological knowledge of the Precambrian of Greenland is described in historical perspective, and an outline of new results is given. The history of geochronology can be roughly divided into three periods: 1) a period of single-sample K-Ar and Rb-Sr mineral or whole-rock age determinations; 2) a time when most ages were determined with the help of Rb-Sr and Pb-Pb whole-rock isochrones and multi-grain zircon U-Pb isotope data; 3) the present, where 'single' zircon U-Pb data are the preferred method to obtain rock ages. These stages in the development of radiometric dating methods partly overlap in time, and each has yielded very significant contributions to the knowledge of Precambiran evolution in Greenland. (EG)

  2. A pan-Precambrian link between deglaciation and environmental oxidation

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    Raub, T.J.; Kirschvink, J.L.

    2007-01-01

    Despite a continuous increase in solar luminosity to the present, Earth’s glacial record appears to become more frequent, though less severe, over geological time. At least two of the three major Precambrian glacial intervals were exceptionally intense, with solid evidence for widespread sea ice on or near the equator, well within a “Snowball Earth” zone produced by ice-albedo runaway in energy-balance models. The end of the first unambiguously low-latitude glaciation, the early Paleoproterozoic Makganyene event, is associated intimately with the first solid evidence for global oxygenation, including the world’s largest sedimentary manganese deposit. Subsequent low-latitude deglaciations during the Cryogenian interval of the Neoproterozoic Era are also associated with progressive oxidation, and these young Precambrian ice ages coincide with the time when basal animal phyla were diversifying. However, specifically testing hypotheses of cause and effect between Earth’s Neoproterozoic biosphere and glaciation is complicated because large and rapid True Polar Wander events appear to punctuate Neoproterozoic time and may have episodically dominated earlier and later intervals as well, rendering geographic reconstruction and age correlation challenging except for an exceptionally well-defined global paleomagnetic database.

  3. Precambrian crustal history of the Nimrod Group, central Transantarctic Mountains

    International Nuclear Information System (INIS)

    Goodge, J.W.; Fanning, C.M.

    2002-01-01

    High-grade metamorphic and igneous rocks of the Nimrod Group represent crystalline basement to the central Transantarctic Mountains. Despite metamorphism and penetrative deformation during the Ross Orogeny, they preserve a deep record of Precambrian geologic history in this sector of the East Antarctic shield. A review of available U-Pb geochronometric data reveals multiple geologic events spanning 2.5 b.y. of Archean to Early Paleozoic time, including: (1) juvenile Archean crust production by magmatism between 3150 and 3000 Ma; (2) crustal stabilisation and metamorphism between 2955 and 2900 Ma; (3) ultra-metamorphism or anatexis at c. 2500 Ma; (4) deep-crustal metamorphism and magmatism between 1720 and 1730 Ma, redefining the Nimrod Orogeny; (5) post-1700 Ma sedimentation; and (6) basement reactivation involving high-grade metamorphism, magmatism, and penetrative deformation during the Ross Orogeny between 540 and 515 Ma. A strong regional metamorphic and deformational Ross overprint, dated by U-Pb and Ar thermochronology, had pronounced thermomechanical effects on the basement assemblage, yet rocks of the Nimrod Group retain robust evidence of their Precambrian ancestry. The zircon U-Pb record therefore demonstrates that primary crustal lithosphere of the East Antarctic shield extends to the central Transantarctic Mountains, and that it has undergone multiple episodes of reactivation culminating in the Ross Orogeny. (author). 48 refs., 2 figs., 1 tab

  4. Precambrian evolution and the rock record

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    Awramik, S.

    1985-01-01

    The Precambrian time which refers to geological time prior to the first appearance of animals with mineralized hard parts was investigated. Best estimates for this event are around 570 million years ago. Because the rock record begins some 3,800 million years ago the Precambrian encompasses about 84% of geologic time. The fossil record for this immense span of time is dominated by prokaryotes and the sedimentary structures produced by them. The first fossil remains that are considered eukaryotic are found in 1,000 million year old rocks. The first animals may be as old as 700 million years. The fossil records of the first 84% of the Earth's history are collected and described.

  5. Historical trends of hypoxia in Changjiang River estuary: Applications of chemical biomarkers and microfossils

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    Li, X.; Bianchi, T.S.; Yang, Z.; Osterman, L.E.; Allison, M.A.; DiMarco, Steven F.; Yang, G.

    2011-01-01

    Over the past two decades China has become the largest global consumer of fertilizers, which has enhanced river nutrient fluxes and caused eutrophication and hypoxia in the Yangtze (Changjiang) large river delta-front estuary (LDE). In this study, we utilized plant pigments, lignin-phenols, stable isotopes (δ13C and δ15N) and foraminiferal microfossils in 210Pb dated cores to examine the history of hypoxia in the Changjiang LDE. Two sediment cores were collected onboard R/V Dong Fang Hong 2 using a stainless-steel box-corer; one at a water depth of 24.7 m on Jun. 15, 2006 and the other at 52 m on Nov. 20, 2007, both in the hypoxic region off the Changjiang LDE. There has been a significant increase in the abundance of plant pigments after 1979 that are indicators of enhanced diatom and cyanobacterial abundance, which agrees with post-1980 record of increasing nutrient loads in the Changjiang River. The increased inputs of terrestrially derived materials to the LDE are largely woody plant sources and most likely due to deforestation that began in the early 1950s. However, post-1960 lignin data did not reflect enhanced loading of woody materials despite continued deforestation possibly due to increased trapping from greater dam construction, a reduction of deforestation in the drainage basin since the last 1990s, and soil conservation practices. The lack of linkages between bulk indices (stable isotopes, % OC, molar C/N ratios) and microfossil/chemical biomarkers may reflect relative differences in the amount of carbon tracked by these different proxies. Although NO3− is likely responsible for most of the changes in phytoplankton production (post 1970s), historical changes in N loading from the watershed and hypoxia on the LDE shelf may not be as well linked in East China Sea (ECS) sediments due to possible denitrification/ammonification processes; finally, increases in low-oxygen tolerant foraminiferal microfossils indicate there has been an increase in the

  6. The nature and origin of nucleus-like intracellular inclusions in Paleoproterozoic eukaryote microfossils.

    Science.gov (United States)

    Pang, K; Tang, Q; Schiffbauer, J D; Yao, J; Yuan, X; Wan, B; Chen, L; Ou, Z; Xiao, S

    2013-11-01

    The well-known debate on the nature and origin of intracellular inclusions (ICIs) in silicified microfossils from the early Neoproterozoic Bitter Springs Formation has recently been revived by reports of possible fossilized nuclei in phosphatized animal embryo-like fossils from the Ediacaran Doushantuo Formation of South China. The revisitation of this discussion prompted a critical and comprehensive investigation of ICIs in some of the oldest indisputable eukaryote microfossils-the ornamented acritarchs Dictyosphaera delicata and Shuiyousphaeridium macroreticulatum from the Paleoproterozoic Ruyang Group of North China-using a suite of characterization approaches: scanning electron microscopy (SEM), transmission electron microscopy (TEM), and focused ion beam scanning electron microscopy (FIB-SEM). Although the Ruyang acritarchs must have had nuclei when alive, our data suggest that their ICIs represent neither fossilized nuclei nor taphonomically condensed cytoplasm. We instead propose that these ICIs likely represent biologically contracted and consolidated eukaryotic protoplasts (the combination of the nucleus, surrounding cytoplasm, and plasma membrane). As opposed to degradational contraction of prokaryotic cells within a mucoidal sheath-a model proposed to explain the Bitter Springs ICIs-our model implies that protoplast condensation in the Ruyang acritarchs was an in vivo biologically programmed response to adverse conditions in preparation for encystment. While the discovery of bona fide nuclei in Paleoproterozoic acritarchs would be a substantial landmark in our understanding of eukaryote evolution, the various processes (such as degradational and biological condensation of protoplasts) capable of producing nuclei-mimicking structures require that interpretation of ICIs as fossilized nuclei be based on comprehensive investigations. © 2013 John Wiley & Sons Ltd.

  7. A model for the biological precipitation of Precambrian iron-formation

    Science.gov (United States)

    Laberge, G. L.

    1986-01-01

    A biological model for the precipitation of Precambrian iron formations is presented. Assuming an oxygen deficient atmosphere and water column to allow sufficient Fe solubility, it is proposed that local oxidizing environments, produced biologically, led to precipitation of iron formations. It is further suggested that spheroidal structures about 30 mm in diameter, which are widespread in low grade cherty rion formations, are relict forms of the organic walled microfossil Eosphaera tylerii. The presence of these structures suggests that the organism may have had a siliceous test, which allowed sufficient rigidity for accumulation and preservation. The model involves precipitation of ferric hydrates by oxidation of iron in the photic zone by a variety of photosynthetic organisms. Silica may have formed in the frustules of silica secreting organisms, including Eosphaera tylerii. Iron formates formed, therefore, by a sediment rain of biologically produced ferric hydrates and silica and other organic material. Siderite and hematite formed diagenetically on basin floors, and subsequent metamorphism produced magnetite and iron silicates.

  8. H2-rich and Hydrocarbon Gas Recovered in a Deep Precambrian Well in Northeastern Kansas

    International Nuclear Information System (INIS)

    Newell, K. David; Doveton, John H.; Merriam, Daniel F.; Lollar, Barbara Sherwood; Waggoner, William M.; Magnuson, L. Michael

    2007-01-01

    In late 2005 and early 2006, the WTW Operating, LLC (W.T.W. Oil Co., Inc.) no. 1 Wilson well (T.D. = 5772 ft; 1759.3 m) was drilled for 1826 ft (556.6 m) into Precambrian basement underlying the Forest City Basin in northeastern Kansas. Approximately 4500 of the 380,000 wells drilled in Kansas penetrate Precambrian basement. Except for two previous wells drilled into the arkoses and basalts of the 1.1-Ga Midcontinent Rift and another well drilled in 1929 in basement on the Nemaha Uplift east of the Midcontinent Rift, this well represents the deepest penetration into basement rocks in the state to date. Granite is the typical lithology observed in wells that penetrate the Precambrian in the northern Midcontinent. Although no cores were taken to definitively identify lithologies, well cuttings and petrophysical logs indicate that this well encountered basement metamorphic rocks consisting of schist, gneiss, and amphibolitic gneiss, all cut by aplite dikes.The well was cased and perforated in the Precambrian, and then acidized. After several days of swabbing operations, the well produced shows of low-Btu gas, dominated by the non-flammable component gases of nitrogen (20%), carbon dioxide (43%), and helium (1%). Combustible components include methane (26%), hydrogen (10%), and higher molecular-weight hydrocarbons (1%). Although Coveney and others [Am. Assoc. Petroleum Geologists Bull., v. 71, no, 1, p. 39-48, 1987] identified H 2 -rich gas in two wells located close to the Midcontinent Rift in eastern Kansas, this study indicates that high levels of H 2 may be a more widespread phenomenon than previously thought. Unlike previous results, the gases in this study have a significant component of hydrocarbon gas, as well as H 2 , N 2 , and CO 2 . Although redox reactions between iron-bearing minerals and groundwater are a possible source of H 2 in the Precambrian basement rocks, the hydrocarbon gas does not exhibit the characteristics typically associated with proposed

  9. Anthracite like coal in the rock of the late Precambrian. [Australia

    Energy Technology Data Exchange (ETDEWEB)

    Dojcinov, D; Pavlovic, N Z; Premovic, P I

    1983-01-01

    The rock of the late Precambrian formation of Paradise Creek (the age is approximately 1.6 million years, Kingsland, Australia) contains an unusually large volume of paramagnetic varieties with properties of free radicals. The presence in this deposit of such varieties confirms the presence in the anthracite coal material of inclusions of primitive protovascular plants of the early Proterozoa in the region of Paradise Creek, Australia.

  10. Microfossil and Fourier transform infrared analyses of Lapita and post-Lapita human dental calculus from Vanuatu, southwest Pacific

    International Nuclear Information System (INIS)

    Horrocks, M.; Nieuwoudt, M.K.; Kinaston, R.; Buckley, H.; Bedford, S.

    2014-01-01

    Here we report on microfossil analysis of human dental calculus from Lapita (3000-2600 yr BP) and post-Lapita (2300-2000 yr BP) burials from Vao and Uripiv, Vanuatu. Phytoliths of introduced Musa and indigenous Heliconia in the calculus suggest the use of these taxa as food wrappings. Phytoliths and most other material in the calculus, namely sponge spicules, calcium oxalate crystals, xylem and charcoal, are unequivocal identifications. Another type of material, comprising degraded objects with a general morphology suggesting starch grains, is uncertain, however, as the unequivocal starch indicator, the Maltese cross, was not observed. We used a new method for calculus analysis, Fourier Transform InfraRed spectroscopy (FTIR), comparing the suspected starch with modern reference starch of prehistoric Pacific crops. Although the ancient FTIR analysis was limited to a small number of suspected starch grains, the results provide another line of evidence for starch. The calculus data are consistent with previous microfossil studies of Lapita deposits at the sites, and demonstrate the efficacy of this technique in contributing to the definition of the history of plant use and diet of early Pacific Island populations. (author)

  11. Characteristics of microfossils assemblages of core SB-01 from Sanshui basin and discussion of paleocene-eocene boundary

    International Nuclear Information System (INIS)

    Chen Liang; Xie Yecai; Wang Zhengqing; Ma Chuang

    2011-01-01

    Characteristics of microfossils assemblages of core SB-01 from Sanshui Basin have been analysised in this paper. Based on micropaleontological study and data from carbon and oxygen isotopes of bulk carbonates, which depth of Paleocene-Eocene boundary from the core was discussed. Ostracode assemblages include the Sinocypris nitela-Cyprois buxinensis-Limnocythere honggangensis assemblage(89.0-73.38 m) with few species and low abundance and the Sinocypris nitela-Cyprois buxinensis-Limnocythere honggangensis assemblage (73.38-0 m) with few species and low abundance during early and middle the core deposition and relatively many species and abundance increasing quickly of the late time of the core deposition; Charophyte assemblages contain the Peckichara subspherica-Rhabdochara jiangduensis assemblage (89.0-73.38 m) with rich species, high abundance and large sizes of fossils and the Gyrogona qianjiangica-Obtusochara brevicylindrica assemblage (73.38-53.75 m) with few species,low abundance and small sizes of fossils. At 73.38 m core depth, the great changes of microfossils assemblages and carbon isotopes values (decrease by more than 3.0 per thousand) and oxygen isotopes values of bulk carbonates take place, which consist with the geological records of the Paleocene-Eocene Thermal Maximum (PETM). Hence, Paleocene-Eocene boundary of SanShui Basin should be roughly placed at 73.38 m core depth. (authors)

  12. Biomarkers and Microfossils in the Murchison, Rainbow, and Tagish Lake meteorites

    Science.gov (United States)

    Hoover, Richard B.; Jerman, Gregory A.; Rozanov, Alexei Y.; Davies, Paul C.

    2003-02-01

    During the past six years, we have conducted extensive scanning electron and optical microscopy investigations and x-ray analysis to determine the morphology, life cycle processes, and elemental distributions in living and fossil cyanobacteria, bacteria, archaea, fungi, and algae sampled from terrestrial environments relevant to Astrobiology. Biominerals, pseudomorphs and microfossils have been studied for diverse microbial groups in various states of preservation in many types of rocks (e.g., oil shales, graphites, shungites, bauxites, limestones, pyrites, phosphorites, and hydrothermal vent chimneys). Results of these studies have been applied to the search for biosignatures in carbonaceous chondrites, stony, and nickel iron meteorites. We review important biomarkers found in terrestrial rocks and meteorites and present additional evidence for the existence of indigenous bacterial microfossils in-situ in freshly fractured surfaces of the Murchison, Rainbow and Tagish Lake carbonaceous meteorites. We provide secondary and backscatter electron images and spectral data obtained with Field Emission and Environmental Scanning Electron Microscopes of biominerals and microfossils. We discuss techniques for discriminating indigenous microfossils from recent terrestrial contaminants. Images are provided of framboidal magnetites in oil shales and meteorites and images and 2D x-ray maps are shown of bacterial microfossils embedded in the mineral matrix of the Murchison, Rainbow and Tagish Lake Carbonaceous Meteorites. These microfossils exhibit characteristics that preclude their interpretation as post-arrival contaminants and we interpret them as indigenous biogenic remains.

  13. Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

    Science.gov (United States)

    Marzen, Rachel; DeNinno, Lauren H.; Cronin, Thomas M.

    2016-01-01

    Microfaunal and geochemical proxies from marine sediment records from central Arctic Ocean (CAO) submarine ridges suggest a close relationship over the last 550 thousand years (kyr) between orbital-scale climatic oscillations, sea-ice cover, marine biological productivity and other parameters. Multiple paleoclimate proxies record glacial to interglacial cycles. To understand the climate-cryosphere-productivity relationship, we examined the cyclostratigraphy of calcareous microfossils and constructed a composite Arctic Paleoclimate Index (API) "stack" from benthic foraminiferal and ostracode density from 14 sediment cores. Following the hypothesis that API is driven mainly by changes in sea-ice related productivity, the API stack shows the Arctic experienced a series of highly productive interglacials and interstadials every ∼20 kyr. These periods signify minimal ice shelf and sea-ice cover and maximum marine productivity. Rapid transitions in productivity are seen during shifts from interglacial to glacial climate states. Discrepancies between the Arctic API curves and various global climatic, sea-level and ice-volume curves suggest abrupt growth and decay of Arctic ice shelves related to climatic and sea level oscillations.

  14. Precambrian uranium deposits as a possible source of uranium for the European Variscan deposits

    International Nuclear Information System (INIS)

    Mineeva, I.G.; Klochkov, A.S.

    2002-01-01

    The Precambrian uranium deposits have been studied on the territory of Baltic and Ukrainian shields. The primary Early Proterozoic complex Au-U deposits originated in granite-greenstone belts as a result of their evolution during continental earth crust formation by prolonged rift genesis. The greenstone belts are clues for revealing ancient protoriftogenic structures. The general regularities of uranium deposition on Precambrian shields are also traceable in Variscan uranium deposits from the Bohemian massif. The Variscan period of uranium ore formation is connected with a polychronous rejuvenation of ancient riftogenous systems and relatively younger processes of oil and gas formation leading to the repeated mobilization of U from destroyed Proterozoic and Riphean uranium deposits. (author)

  15. Uranium assessment for the Precambrian pebble conglomerates in southeastern Wyoming

    International Nuclear Information System (INIS)

    Borgman, L.E.; Sever, C.; Quimby, W.F.; Andrew, M.E.; Karlstrom, K.E.; Houston, R.S.

    1981-03-01

    This volume is a geostatistical resource estimate of uranium and thorium in quartz-pebble conglomerates, and is a companion to Volume 1: The Geology and Uranium Potential to Precambrian Conglomerates in the Medicine Bow Mountains and Sierra Madre of Southeastern Wyoming; and to Volume 2: Drill-Hole Data, Drill-Site Geology, and Geochemical Data from the Study of Precambrian Uraniferous Conglomerates of the Medicine Bow Mountains and the Sierra Madre of Southeastern Wyoming

  16. Soil stabilization by a prokaryotic desert crust: implications for Precambrian land biota.

    Science.gov (United States)

    Campbell, S E

    1979-09-01

    A cyanophyte dominated mat, desert crust, forms the ground cover in areas measuring hundreds of square meters in Utah and smaller patches in Colorado. The algal mat shows stromatolitic features such as sediment trapping and accretion, a convoluted surface, and polygonal cracking. Sand and clay particles are immobilized by a dense network of filaments of the two dominating cyanophyte species, Microcoleus vaginatus and M. chthonoplastes, which secrete sheaths to which particles adhere. These microorganisms can tolerate long periods of desiccation and are capable of instant reactivation and migration following wetting. Migration occurs in two events: 1. immediately following wetting of dry mat, trichomes are mechanically expelled from the sheath as it swells during rehydration, and 2. subsequently, trichomes begin a self-propelled gliding motility which is accompanied by further production of sheath. The maximum distance traveled on solid agar by trichomes of Microcoleus vaginatus during a 12 hour period of light was 4.8 cm. This corresponds to approximately 500 times the length of the fastest trichome, and provides a measure of the potential for spreading of the mat in nature via the motility of the trichomes. Dehydration resistence of the sheath modifies the extracellular environment of the trichomes and enables their transition to dormancy. Following prolonged wetting and evaporative drying of the mat in the laboratory, a smooth wafer-like crust is formed by the sheaths of Microcleus trichomes that have migrated to the surface. Calcium carbonate precipitates among the algal filaments under experimental conditions, indicating a potential for mat lithification and fossilization in the form of a caliche crust. It is suggested that limestones containing tubular microfossils may, in part, be of such an origin. The formation of mature Precambrian soils may be attributable to soil accretion, stabilization, and biogenic modification by blue-green algal land mats similar to

  17. Uinta Arch Project: investigations of uranium potential in Precambrian X and older metasedimentary rocks in the Unita and Wasatch ranges, Utah and Colorado

    International Nuclear Information System (INIS)

    Graff, P.J.; Sears, J.W.; Holden, G.S.

    1980-06-01

    This study is part of the United States Department of Energy's National Uranium Resource Evaluation Program to understand the geologic setting, amount, and availability of uranium resources within the boundaries of the United States. The systematic study of Precambrian quartz-pebble conglomerates and areas that may contain such conglomerates is an integral part of DOE's resource evaluation program, because deposits of world-wide importance occur in such terrains in Canada and South Africa, and because terrains similar to those producing uranium from quartz-pebble conglomerates exist elsewhere in the United States. Because of the ready availability of Tertiary sandstone and Colorado Plateau-type uranium deposits, large areas of Precambrian rocks in the US have not been fully assessed for uranium potential. Thus, the Uinta Arch Project was undertaken to assess the favorability of Precambrian metasedimentary rocks in northern Utah for deposits of uranium in Precambrian quartz-pebble conglomerates. Rocks of interest to this study are the thick, clastic sequences within the Uinta Arch that are considered to be of Early Proterozoic age. The Uinta Arch area is known to contain rocks which generally fit the lithologic characteristics that are understood to limit the occurrence of Precambrian fossil placers. However, detailed geology of these rocks and their exact fit to the model described for uraniferous conglomerates was not known. The primary goal of the Uinta Arch Project was to determine how well these Precambrian rocks resemble known deposits and to describe the favorability of placer uranium deposits

  18. Biogenic silica microfossils in sediments of the Permian - Carboniferous Unayzah Formation, Saudi Arabia

    NARCIS (Netherlands)

    Garming, J.F.L.; Franks, S.G.; Cremer, H.; Abbink, O.A.

    2010-01-01

    Biogenic silica particles (BSPs) have been discovered in sediments of the Permian - Carboniferous Unayzah Formation of Saudi Arabia. The BSPs are extracted from sediments that are generally barren of macro- or microfossils. BSPs have been found in the Basal Khuff Clastics (BKC), and the Unayzah A,

  19. Excess europium content in Precambrian sedimentary rocks and continental evolution

    Science.gov (United States)

    Jakes, P.; Taylor, S. R.

    1974-01-01

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

  20. Analysis of lineament swarms in a Precambrian metamorphic rocks

    Indian Academy of Sciences (India)

    Addressing the geologic significance of lineaments and their correlation with joints/fractures is still unclear. The present study attempts to analyse the lineament swarms developed in a Precambrian metamorphic terrain in India using both unfiltered and filtered techniques. The unfiltered analysis technique shows that the ...

  1. Anoxic and oxic phototrophic primary production during the Precambrian

    DEFF Research Database (Denmark)

    Ebey-Honeycutt, Christina Marie; Bjerrum, Christian J.; Canfield, Donald Eugene

    2009-01-01

    of the mixed layer often lies above the base of the photic zone . Thus, an ecosystem model for the Precambrian should reflect the net primary production (NPP) of oxygenic phototrophs in the mixed layer and anoxygenic phototrophs below (NPPox and NPPred, respectively). Satelite data and a vertically generalized...

  2. Fossil Record of Precambrian Life on Land

    Science.gov (United States)

    Knauth, Paul

    2000-01-01

    The argument that the earth's early ocean was up to two times modern salinity was published in 'Nature' and presented at the 1998 Annual Meeting of the Geological Society of America in Toronto. The argument is bolstered by chemical data for fluid inclusions in Archean black smokers. The inclusions were 1.7 times the modern salinity causing the authors to interpret the parent fluids as evaporite brines (in a deep marine setting). I reinterpreted the data in terms of the predicted value of high Archean salinities. If the arguments I presented are on track, early life was either halophilic or non-marine. Halophiles are not among the most primitive organisms based on RNA sequencing, so here is an a priori argument that non-marine environments may have been the site of most early biologic evolution. This result carries significant implications for the issue of past life on Mars or current life on the putative sub-ice oceans on Europa and possibly Callisto. If the Cl/H2O ratio on these objects is similar to that of the earth, then oceans and oceanic sediments are probably not the preferred sites for early life. On Mars, this means that non-marine deposits such as caliche in basalt may be an overlooked potential sample target.

  3. The First Evidence of the Precambrian Basement in the Fore Range Zone of the Great Caucasus.

    Science.gov (United States)

    Latyshev, A.; Kamzolkin, V.; Vidjapin, Y.; Somin, M.; Ivanov, S.

    2017-12-01

    Within the Great Caucasus fold-thrust belt, the Fore Range zone has the most complicated structure, and the highest degree of metamorphism was found there. This zone consists of several salients with the different composition and the structural and metamorphic evolution. The largest Blyb salient includes the metamorphic basement covered by the pack of thrusts. According to the recent isotopic data the upper levels of the Blyb metamorphic complex (BMC) are supposed to be Middle-Paleozoic (Somin, 2011). We studied zircons from the granitic intrusions located in the metamorphic rocks of the BMC. The U-Pb dating (SHRIMP II, VSEGEI, Russia) of zircons from the large Balkan metadiorite massif yielded the ages of 549±7,4, 574,1±6,7, and 567,9±6,9 Ma. All studied zircons show the high Th/U ratios and likely have the magmatic origin. This data is the first confirmation of the presence of the Precambrian basement and Vendian magmatic activity in the Fore Range zone. Zircons from the Unnamed granodiorite massif from the south of the Blyb salient yielded the age of 319±3.8 Ma (the Early Carboniferous). This fact taken together with the low grade of metamorphism in this intrusion reveals the Late Paleozoic magmatic event in the Fore Range zone. We also suggest that the Precambrian basement of the BMC, including the Balkan intrusion, is covered by so-called Armovsky nappe. This is confirmed by the field data, Middle-Paleozoic U-Pb ages and the higher degree of metamorphism of the Armovsky gneisses and schists. Thus, the BMC is not uniform but includes the blocks of the different age and metamorphic grades. Finally, we measured the anisotropy of magnetic susceptibility (AMS) of the Balkan metadiorites. The axes of AMS ellipsoid fix the conditions of the north-east compression, as well as the strain field reconstructed from the macrostructures orientation, which corresponds to the thrusts propagation. Therefore, the emplacement of the Balkan massif happened before the thrust

  4. Digital database of microfossil localities in Alameda and Contra Costa Counties, California

    Science.gov (United States)

    McDougall, Kristin; Block, Debra L.

    2014-01-01

    The eastern San Francisco Bay region (Contra Costa and Alameda Counties, California) is a geologically complex area divided by faults into a suite of tectonic blocks. Each block contains a unique stratigraphic sequence of Tertiary sediments that in most blocks unconformably overlie Mesozoic sediments. Age and environmental interpretations based on analysis of microfossil assemblages are key factors in interpreting geologic history, structure, and correlation of each block. Much of this data, however, is distributed in unpublished internal reports and memos, and is generally unavailable to the geologic community. In this report the U.S. Geological Survey microfossil data from the Tertiary sediments of Alameda and Contra Costa counties are analyzed and presented in a digital database, which provides a user-friendly summary of the micropaleontologic data, locality information, and biostratigraphic and ecologic interpretations.

  5. Search for supernova {sup 60}Fe in the Earth's microfossil record

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, S.; Ludwig, P.; Egli, R.; Faestermann, T.; Korschinek, G.; Rugel, G. [Technische Universitaet Muenchen, James Franck Str. 1, D-85748 Garching (Germany); Department of Earth and Environmental Sciences, Ludwig-Maximilians University, Theresienstrasse 41 80333 Munich (Germany); Technische Universitaet Muenchen, James Franck Str. 1, D-85748 Garching (Germany); Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstra. 400, D-01328 Dresden (Germany)

    2012-11-12

    Approximately 2.8 Myr before the present our planet was subjected to the debris of a supernova explosion. The terrestrial proxy for this event was the discovery of live atoms of {sup 60}Fe in a deep-sea ferromanganese crust. The signature for this supernova event should also reside in magnetite (Fe{sub 3}O{sub 4}) microfossils produced by magnetotactic bacteria extant at the time of the Earth-supernova interaction, provided the bacteria preferentially uptake iron from fine-grained iron oxides and ferric hydroxides. Using empirically derived microfossil concentrations in a deep-sea drill core, we deduce a conservative estimate of the {sup 60}Fe fraction as {sup 60}Fe/Fe Almost-Equal-To 3.6 Multiplication-Sign 10{sup -15}. This value sits comfortably within the sensitivity limit of present accelerator mass spectrometry capabilities.

  6. Using Soft Sculpture Microfossils and Other Crafted Models to Teach Geoscience

    Science.gov (United States)

    Spinak, N. R.

    2017-12-01

    For the past 5 years, the International Ocean Discovery Program (IODP) has been using the author's sewn models of microfossils to help learners understand the shapes and design of these tiny fossils. These tactile objects make the study of ancient underwater life more tangible. Multiple studies have shown that interactive models can help many learners understand science. The Montessori and Waldorf education programs are based in large part on earlier insights into meeting these needs. The act of drawing has been an essential part of medical education. The STEAM (Science, Technology, Engineering, Arts and Math) movement has advocated for STEM supporters to recognize the inseparability of science and art. This presentation describes how the author's knitted or sewn models of microfossils incorporate art and design into geoscience education. The geoscience research and art processes used in developing and creating these educational soft sculptures will be described. In multiple entry points to science study, specific reciprocal benefits to boundary crossing among the arts and sciences for those who have primary talents in a particular area of study will be discussed. Geoscience education can benefit from using art and craft items such as models. Many websites now offer soft sculptures for biology study such as organs and germs (e.g. (https://www.giantmicrobes.com/us/main/nasty-germs). The Wortheim project involving community and crochet is another approach (http://crochetcoralreef.org/). These tactile artifacts give learners an entry-level experience with biology. Three dimensional models are multisensory. The enlarged manipulative microfossil models invite learners to make comparisons and gain insights when microscopes are not available or appropriate for the audience. Adding the physical involvement of creating a microfossil yourself increases the multi-sensory experience even further. Learning craft skills extends the cross-cutting concepts of the NGSS to a mutual

  7. Uranium and thorium occurrences in Precambrian rocks, Upper Peninsula of Michigan and northern Wisconsin, with thoughts on other possible settings

    International Nuclear Information System (INIS)

    Kalliokoski, J.

    1976-01-01

    The following areas are covered: Precambrian geology of northern Michigan; mode of occurrence of uranium and thorium in the Precambrian rocks of the Upper Peninsula of Michigan; selected stratigraphic relationships, Precambrian rocks of Michigan; mode of occurrence of uranium and thorium in Precambrian rocks of Wisconsin; and background data for geochemical exploration

  8. The lunar nodal tide and the distance to tne Moon during the Precambrian era

    Science.gov (United States)

    Walker, J. C. G.; Zahnle, K. J.

    1986-01-01

    The origin and early evolution of life on Earth occurred under physical and chemical conditions distinctly different from those of the present day. The broad goal of this research program is to characterize these conditions. One aspect involves the dynamics of the Earth-Moon system, the distance of the Moon from the Earth, and the length of the day. These have evolved during the course of Earth history as a result of the dissipation of tidal energy. As the moon has receded the amplitude of oceanic tides has decreased while the increasing length of the day should have influenced climate and the circulation of atmosphere and ocean. A 23.3 year periodicity preserved in a 2500 million year old banded iron-formation was interpreted as reflecting the climatic influence of the lunar nodal tide. The corresponding lunar distance would then have been approx. 52 Earth radii. The influence of the lunar nodal tide is also apparent in rocks with an age of 680 million years B.P. The derived value for lunar distance 2500 million years ago is the only datum on the dynamics of the Earth-Moon system during the Precambrian era of Earth history. The implied development of Precambrian tidal friction is in accord with more recent paleontological evidence as well as the long term stability of the lunar orbit.

  9. The Cuatro Ciénegas Basin in Coahuila, Mexico: An Astrobiological Precambrian Park

    Science.gov (United States)

    Siefert, Janet L.; Escalante, Ana E.; Elser, James J.; Eguiarte, Luis E.

    2012-01-01

    Abstract The Cuatro Ciénegas Basin (CCB) is a rare oasis in the Chihuahuan Desert in the state of Coahuila, Mexico. It has a biological endemism similar to that of the Galapagos Islands, and its spring-fed ecosystems have very low nutrient content (nitrogen or phosphorous) and are dominated by diverse microbialites. Thus, it has proven to be a distinctive opportunity for the field of astrobiology, as the CCB can be seen as a proxy for an earlier time in Earth's history, in particular the late Precambrian, the biological frontier when prokaryotic life yielded at least partial dominance to eukaryotes and multicellular life. It is a kind of ecological time machine that provides abundant opportunities for collaborative investigations by geochemists, geologists, ecologists, and population biologists in the study of the evolutionary processes that structured Earth-based life, especially in the microbial realm. The CCB is an object of investigation for the identification of biosignatures of past and present biota that can be used in our search for extraterrestrial life. In this review, we summarize CCB research efforts that began with microbial ecology and population biology projects and have since been expanded into broader efforts that involve biogeochemistry, comparative genomics, and assessments of biosignatures. We also propose that, in the future, the CCB is sanctioned as a “Precambrian Park” for astrobiology. Key Words: Microbial mats—Stromatolites—Early Earth—Extremophilic microorganisms—Microbial ecology. Astrobiology 12, 641–647. PMID:22920514

  10. Uinta Arch Project: investigations of uranium potential in Precambrian X and older metasedimentary rocks in the Unita and Wasatch ranges, Utah and Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Graff, P.J.; Sears, J.W.; Holden, G.S.

    1980-06-01

    This study is part of the United States Department of Energy's National Uranium Resource Evaluation Program to understand the geologic setting, amount, and availability of uranium resources within the boundaries of the United States. The systematic study of Precambrian quartz-pebble conglomerates and areas that may contain such conglomerates is an integral part of DOE's resource evaluation program, because deposits of world-wide importance occur in such terrains in Canada and South Africa, and because terrains similar to those producing uranium from quartz-pebble conglomerates exist elsewhere in the United States. Because of the ready availability of Tertiary sandstone and Colorado Plateau-type uranium deposits, large areas of Precambrian rocks in the US have not been fully assessed for uranium potential. Thus, the Uinta Arch Project was undertaken to assess the favorability of Precambrian metasedimentary rocks in northern Utah for deposits of uranium in Precambrian quartz-pebble conglomerates. Rocks of interest to this study are the thick, clastic sequences within the Uinta Arch that are considered to be of Early Proterozoic age. The Uinta Arch area is known to contain rocks which generally fit the lithologic characteristics that are understood to limit the occurrence of Precambrian fossil placers. However, detailed geology of these rocks and their exact fit to the model described for uraniferous conglomerates was not known. The primary goal of the Uinta Arch Project was to determine how well these Precambrian rocks resemble known deposits and to describe the favorability of placer uranium deposits.

  11. Lead-isotope inhomogeneity in Precambrian igneous K-feldspars

    International Nuclear Information System (INIS)

    Ludwig, K.R.; Silver, L.T.

    1977-01-01

    Stepwise PB-removal experiments, using both vacuum volatilization and HF-leaching techniques, on acid-washed K-feldspar concentrates from Precambrian igneous rocks show that all contain some unsupported radiogenic Pb. Two types of radiogenic Pb were recognised. One has a 'normal' isotopic composition, with relative abundances of 206 Pb, 207 Pb and 208 Pb consistent with the age and U-Th contents of the rocks. The other type of unsupported radiogenic lead in the feldspars is apparently pure 206 Pb, derived from long-term migration and accumulation of radioactive daughter(s) of 238 U. This 'pure' 206 Pb lead occupies different sites from the 'normal' radiogenic lead, and tends to show a release maximum during vacuum volatilization at about 1150 0 C. The usefulness of stepwise vacuum volatilization may be limited by the tendency of a small amount of radiogenic lead to concentrate in the least volatile fraction. Stepwise partial HF attacks appear to give at least as good separation of radiogenic from original feldspar lead, and are recommended as a routine procedure for isotopic analyses of Precambrian feldspars. The fact that most of the five K-feldspars examined contained unsupported radiogenic lead implies that caution must be used in applying total-sample lead analyses of Precambrian feldspars to problems of lead-isotope evolution in crustal rocks. (author)

  12. Global Carbon Cycle of the Precambrian Earth

    DEFF Research Database (Denmark)

    Wiewióra, Justyna

    The carbon isotopic composition of distinct Archaean geological records provides information about the global carbon cycle and emergence of life on early Earth. We utilized carbon isotopic records of Greenlandic carbonatites, diamonds, graphites, marbles, metacarbonates and ultramafic rocks...... in the surface environment and recycled back into the mantle In the third manuscript we investigate the carbon cycle components, which have maintained the carbon isotope composition of the mantle constant through time. Assuming constant organic ratio of the total carbon burial (f), we show that increased.......1‰) and metacarbonate ( -6.1 ± 0.1‰ to +1.5 ± 0.0‰) rocks from the ~3.8 Ga Isua Supracrustal Belt as resulting from the Rayleigh distillation process, which affected the ultramafic reservoir with initial δ13C between -2‰ and 0‰. Due to its high primary δ13C signature, carbon in the Isuan magnesite was most likely...

  13. Alternating Si and Fe deposition caused by temperature fluctuations in Precambrian oceans

    DEFF Research Database (Denmark)

    Posth, Nicole; Hegler, Florian; Konhauser, Kurt

    2008-01-01

    and geochemical modelling to study the potential for a microbial mechanism in the formation of alternating iron–silica bands. We find that the rate of biogenic iron(III) mineral formation by iron-oxidizing microbes reaches a maximum between 20 and 25 °C. Decreasing or increasing water temperatures slow microbial......Precambrian banded iron formations provide an extensive archive of pivotal environmental changes and the evolution of biological processes on early Earth. The formations are characterized by bands ranging from micrometre- to metre-scale layers of alternating iron- and silica-rich minerals. However...... iron mineral formation while promoting abiotic silica precipitation. We suggest that natural fluctuations in the temperature of the ocean photic zone during the period when banded iron formations were deposited could have led to the primary layering observed in these formations by successive cycles...

  14. The precambrian crustal evolution and mineralization cycle of uranium in the northeast of norern China platform

    International Nuclear Information System (INIS)

    Guo Zhitian.

    1986-01-01

    According to the evolution history of the crust the region is divided into three Precambrian structural structural units: (1) Archaean craton; (2) Early Proterozoic zone of fold; (3) Middle-late Proterozoic depression zone. The Archaean-craton mainly consists of granite complex and metasediments. They form the first generation of uranium sources. Proterozoic is characterized by the obvious cycle of sedimentation which consists of the second generation of uranium source. There were multiplestage and congenetic nature in the formation of uranium deposit. The mineralization of uranium coincides with geotectonicdeveloping stage -- igneous activity -- metamorphism in their time. The formation of uranium deposits generally underwent the weathering and erosion of original uraniferous bodies-the migration, redeposition and reformed concentration by metamorphism and metamorphosed hydrothermal solution, and the mineralization was not only of intermittence, but also of inheritance. The evolutional process of forming uranium deposits undergoing various geological function of a structural cycle in the uranium geochemical anomalous area is called uranium mineralizational cycle. The Northeast of Northern China Platform had undergone multiple times structural movements causing migration and concentration of uranium and having mutiple cycle mineralizational character. Corresponding to the three main developing stages of the crustal evolution the Precambrian uranium mineralization in the Northeast of northern China platform area may be divided into three cycles: Late Archaeozoic mineralizational cycle, Early Proterozoic mineralizational cycle, and Middle Proterozoic mineralizational cycle. It is possible to search for potential uranium metallogenetic provinces to study the crustal evolution and the multiple cycle characters of uranium minerogenetic process in the Northern China platform

  15. Thermal maturity of Tasmanites microfossils from confocal laser scanning fluorescence microscopy

    Science.gov (United States)

    Hackley, Paul C.; Kus, Jolanta

    2015-01-01

    We report here, for the first time, spectral properties of Tasmanites microfossils determined by confocal laser scanning fluorescence microscopy (CLSM, using Ar 458 nm excitation). The Tasmanites occur in a well-characterized natural maturation sequence (Ro 0.48–0.74%) of Devonian shale (n = 3 samples) from the Appalachian Basin. Spectral property λmax shows excellent agreement (r2 = 0.99) with extant spectra from interlaboratory studies which used conventional fluorescence microscopy techniques. This result suggests spectral measurements from CLSM can be used to infer thermal maturity of fluorescent organic materials in geologic samples. Spectra of regions with high fluorescence intensity at fold apices and flanks in individual Tasmanites are blue-shifted relative to less-deformed areas in the same body that have lower fluorescence intensity. This is interpreted to result from decreased quenching moiety concentration at these locations, and indicates caution is needed in the selection of measurement regions in conventional fluorescence microscopy, where it is common practice to select high intensity regions for improved signal intensity and better signal to noise ratios. This study also documents application of CLSM to microstructural characterization of Tasmanites microfossils. Finally, based on an extant empirical relation between conventional λmax values and bitumen reflectance, λmax values from CLSM of Tasmanites microfossils can be used to calculate a bitumen reflectance equivalent value. The results presented herein can be used as a basis to broaden the future application of CLSM in the geological sciences into hydrocarbon prospecting and basin analysis.

  16. Microfossils in the Ordovician erratic boulders from South-western Finland

    Directory of Open Access Journals (Sweden)

    Nõlvak, J.

    1995-12-01

    Full Text Available Chitinozoans, ostracods and acritarchs found in four glacially transported limestone boulders from the south-western coast of Finland have been studied in order to test the usefulness of these microfossil groups in age determinations. Also rare specimens of conodonts, inarticulated brachiopods and foraminifers were found. Baltic limestone (or Östersjö limestone was the most problematic, because only fossils with calcitic or phosphatic shells are preserved. It is concluded that the boulders identified correlate with the Uhaku and Rakvere stages of the Middle Ordovician.

  17. Methane as a Climate Driver During the Precambrian Eon (Invited)

    Science.gov (United States)

    Kasting, J. F.

    2013-12-01

    Methane is an important greenhouse gas today even at a relatively low concentration of ~1.7 ppmv. Prior to 2.4 Ga, atmospheric O2 concentrations were low, and CH4 could have been much more abundant, perhaps 500-1000 ppmv (1,2). When supplemented by elevated CO2, CH4 could have played a major role in offsetting reduced solar luminosity and keeping the early Earth habitable. Calculations using both 1-D (3) and 3-D (4) climate models suggest that near-modern surface temperatures could have been maintained at 2.8 Ga at 80% solar luminosity by ~0.02 bar CO2 and 1000 ppmv CH4. Such CO2 levels are near the upper limit derived for that period from analysis of paleosols (5). Some 10-12 K of the calculated surface warming in these models comes from CH4; hence, if CH4 concentrations decreased as O2 levels rose, the climate could have suddenly become much colder. This hypothesis can thus explain the timing of the Paleoproterozoic glaciations at 2.2-2.45 Ga, which may have been global in nature (6). An earlier glaciation at ~2.9 Ga might also have been related to CH4, possibly by the development of a thick, anti-greenhouse organic haze layer (7). Alternatively, the recent realization that, at high concentrations, H2 is an even better greenhouse gas than CH4 (8), suggests that the 2.9-Ga glaciation might have been caused by the appearance of methanogens, which would have drawn down atmospheric H2 by converting it to CH4. In either case, the Archean climate control mechanism would have had a distinctly 'Gaian' nature (9). Finally, the initial rise of O2 at 2.4 Ga need not have spelled the end of CH4 as a major climate driver. If the deep oceans remained anoxic throughout most of the Proterozoic (10), marine sediments could have been strong sources of CH4, unlike today. Calculations (11,12) suggest that CH4 concentrations of 100 ppmv are still possible during this time period, and that the combined greenhouse effect of CH4 and N2O could have approached 10 K. A second rise in O2

  18. Ted Irving and the Precambrian continental drift of (within?) the Canadian Shield

    Science.gov (United States)

    Hoffman, P. F.

    2014-12-01

    Ted Irving was no stranger to the Precambrian when he began paleomagnetic studies in the Canadian Shield (CS) that would dominate his research in the early and mid-1970's. Twenty years before, his graduate work on billion-year-old strata in Scotland established paleomagnetic methodologies applicable to sedimentary rocks generally. In 1958, he and Ronald Green presented an 'Upper Proterozoic' APW path from Australia as evidence for pre-Carboniferous drift relative to Europe and North America (the poles actually range in age from 1.2 to 2.7 Ga). His first published CS poles were obtained from the Franklin LIP of the Arctic platform and demonstrate igneous emplacement across the paleoequator. Characteristically, his 1971 poles are statistically indistinguishable from the most recent grand mean paleopole of 2009. His main focus, however, was on the question of Precambrian continental drift. He compared APW paths with respect to Laurentia with those obtained from other Precambrian shields, and he compared APW paths from different tectonic provinces within the CS. He was consistently antagonistic to the concept of a single long-lived Proterozoic supercontinent, but he was on less certain ground regarding motions within the CS due to inadequate geochronology. With Ron Emslie, he boldly proposed rapid convergence between parts of the Grenville Province and Interior Laurentia (IL) ~1.0 Ga. This was controversial given the uncertain ages of multiple magnetic components in high-grade metamorphic rocks. With John McGlynn and John Park, he developed a Paleoproterozoic APW path for the Slave Province from mafic dikes and red clastics, encompassing the time of consolidation of IL during 2.0-1.8 Ga orogenesis. Before 1980, he constructed Paleoproterozoic APW paths for IL as a whole, finding little evidence for significant internal displacement. He recognized that the Laurentian APW path describes a series of straight tracks linked by hairpins, the latter corresponding in age to

  19. Paleobiology of a microfossil of Bambui group (Proterozoico Superior) from Unai region

    International Nuclear Information System (INIS)

    Simonetti, C.; Fairchild, T.R.

    1989-01-01

    A moderately well-preserved and abundant assemblage of coccoidal, bacilliform, and filamentous organic-walled microfossils is here described from black chert colleted near the top of a 30 m-thick expossure of predominantly microbially laminated dolostone from the lower part of the Upper Proterozoic Bambui Group, 12,5 Km NW of Unai, Minas Gerais, south-central Brazil. Of the 11 morphotypes described in this study, small colonies of coccoidal cells (3 species of Myxococcoides; Glenobotrydion aenigmatis Schopf; Form A) are most abundant, followed by tubular filaments (Siphonophycus sp.; 2 species of Eomycetopsis), and, finally, rare, solitary, large (20-40 μ) coccoidal forms (Form C) and a single colony of bacilliform cells (Eosynechococcus moorei Hofmann). The assemblage is dominated by apparently planktonic, small-celled (rarely exceeding 13 μ), colonial coccoidal forms, although filamentous forms may have played a significant role in the local benthos, as suggested by faintly preserved, palimpsestic (or 'ghost') filamentous fabrics and by the presence of poorly preserved tubes of Siphonophycus up to 32 μ in diameter. A single, large pair of thick-walled coccoidal cells (Form B) is here interpreted as a possible acritarch of as yet undetermined biostratigraphic value. The generally small, simple microfossils of this assemblage are similar to elements of the five other Known Bambui assemblages and apparently rather typical of many other late Proterozoic microfloras. (author) [pt

  20. Microfossil measures of rapid sea-level rise: Timing of response of two microfossil groups to a sudden tidal-flooding experiment in Cascadia

    Science.gov (United States)

    Horton, B.P.; Milker, Yvonne; Dura, T.; Wang, Kelin; Bridgeland, W.T.; Brophy, Laura S.; Ewald, M.; Khan, Nicole; Engelhart, S.E.; Nelson, Alan R.; Witter, Robert C.

    2017-01-01

    Comparisons of pre-earthquake and post-earthquake microfossils in tidal sequences are accurate means to measure coastal subsidence during past subduction earthquakes, but the amount of subsidence is uncertain, because the response times of fossil taxa to coseismic relative sea-level (RSL) rise are unknown. We measured the response of diatoms and foraminifera to restoration of a salt marsh in southern Oregon, USA. Tidal flooding following dike removal caused an RSL rise of ∼1 m, as might occur by coseismic subsidence during momentum magnitude (Mw) 8.1–8.8 earthquakes on this section of the Cascadia subduction zone. Less than two weeks after dike removal, diatoms colonized low marsh and tidal flats in large numbers, showing that they can record seismically induced subsidence soon after earthquakes. In contrast, low-marsh foraminifera took at least 11 months to appear in sizeable numbers. Where subsidence measured with diatoms and foraminifera differs, their different response times may provide an estimate of postseismic vertical deformation in the months following past megathrust earthquakes.

  1. Late Silurian fish microfossils from an East Baltic-derived erratic from Oosterhaule, with a description of new acanthodian taxa

    NARCIS (Netherlands)

    Vergoossen, JMJ

    1999-01-01

    Fish microfossils were extracted from an erratic. The taxa from the rich microvertebrate fauna of late Pridolian (latest Silurian) age ( P. punctatus Zone) are listed. A full description is given of two new Gomphonchus taxa, G. mediocostatus and G. boekschoteni. On the basis of old and new material,

  2. Pre-cambrian geochronology in Rio Grande do Norte, Brazil

    International Nuclear Information System (INIS)

    Galindo, A.C.

    1981-08-01

    The Precambrian region polyciclic caracter, in the Rio Grande do Norte State has make difficulties to its geochronological and geological studies. Four importants tectonometamorphic occurences identified dissimulate the original isotopic composition of the rocks. Is much defined the presence of three geochronological events wich left vestiges in the differents Serido litological units. The first event is related with Jequie cicle (2,7 b.y) and related with the Caico Group rocks. The second important event define the Transamazonic cicle (2.1 b.y). The third is correlated with Brazilian Cicle, when occurred the granitoids and pegmatites bodies formation. This third event was the last in this region and affect the other units too. (C.D.G.) [pt

  3. Evolution of major metabolic innovations in the Precambrian

    Science.gov (United States)

    Barnabas, J.; Schwartz, R. M.; Dayhoff, M. O.

    1982-01-01

    A combination of information on the metabolic capabilities of prokaryotes with a composite phylogenetic tree depicting an overview of prokaryote evolution based on the sequences of bacterial ferredoxin, 2Fe-2S ferredoxin, 5S ribosomal RNA, and c-type cytochromes shows three zones of major metabolic innovation in the Precambrian. The middle of these, which reflects the genesis of oxygen-releasing photosynthesis and aerobic respiration, links metabolic innovations of the anaerobic stem on the one hand and, on the other, proliferation of aerobic bacteria and the symbiotic associations leading to the eukaryotes. Those pathways where information on the structure of the enzymes is known are especially considered. Halobacterium and Thermoplasma (archaebacteria) do not belong to a totally independent line on the basis of the composite tree but branch from the eukaryote cytoplasmic line.

  4. Export of nutrients from golf courses on the Precambrian Shield

    International Nuclear Information System (INIS)

    Winter, Jennifer G.; Dillon, Peter J.

    2006-01-01

    Annual export rates, or fluxes, of total nitrogen (TN), nitrate, total phosphorus (TP) and potassium from four streams on two golf courses on the Precambrian Shield were compared with those from forested reference locations. Overall, the mean annual fluxes of K, TN, NO 3 and TP from golf courses were greater than from forested areas by 10, 2, 6 and 2 times, respectively. The overall mean export coefficients (kg/ha/yr) were 16 for K, 5.2 for TN, 2.1 for NO 3 and 0.14 for TP. For TN and TP, these are similar to those reported from cropland in Canada by Chambers and Dale (1997. Contribution of industrial, municipal, agricultural and groundwater sources to nutrient export, Athabasca, Wapiti and Smoky Rivers, 1980 to 1993. Northern River Basins Study Project Report No. 110. Northern River Basins Study, Edmonton, Alberta). -- Golf courses increase nutrient loads in receiving streams

  5. Hydrology of some deep mines in Precambrian rocks

    Energy Technology Data Exchange (ETDEWEB)

    Yardley, D.H.

    1975-10-01

    A number of underground mines were investigated during the summer of 1975. All of them are in Precambrian rocks of the Lake Superior region. They represent a variety of geologic settings. The purpose of the investigations was to make a preliminary study of the dryness, or lack of dryness of these rocks at depth. In other words, to see if water was entering the deeper workings through the unmined rock by some means such as fracture or fault zones, joints or permeable zones. Water entering through old mine workings extending to, or very near to the surface, or from the drilling equipment, was of interest only insofar as it might mask any water whose source was through the hanging or footwall rocks. No evidence of running, seeping or moving water was seen or reported at depths exceeding 3,000 feet. At depths of 3,000 feet or less, water seepages do occur in some of the mines, usually in minor quantities but increased amounts occur as depth becomes less. Others are dry at 2,000 feet of depth. Rock movements associated with extensive mining should increase the local secondary permeability of the rocks adjoining the mined out zones. Also most ore bodies are located where there has been a more than average amount of faulting, fracturing, and folding during the geologic past. They tend to cluster along crustal flows. In general, Precambrian rocks of similar geology, to those seen, well away from zones that have been disturbed by extensive deep mining, and well away from the zones of more intense geologic activity ought to be even less permeable than their equivalents in a mining district.

  6. Hydrology of some deep mines in Precambrian rocks

    International Nuclear Information System (INIS)

    Yardley, D.H.

    1975-10-01

    A number of underground mines were investigated during the summer of 1975. All of them are in Precambrian rocks of the Lake Superior region. They represent a variety of geologic settings. The purpose of the investigations was to make a preliminary study of the dryness, or lack of dryness of these rocks at depth. In other words, to see if water was entering the deeper workings through the unmined rock by some means such as fracture or fault zones, joints or permeable zones. Water entering through old mine workings extending to, or very near to the surface, or from the drilling equipment, was of interest only insofar as it might mask any water whose source was through the hanging or footwall rocks. No evidence of running, seeping or moving water was seen or reported at depths exceeding 3,000 feet. At depths of 3,000 feet or less, water seepages do occur in some of the mines, usually in minor quantities but increased amounts occur as depth becomes less. Others are dry at 2,000 feet of depth. Rock movements associated with extensive mining should increase the local secondary permeability of the rocks adjoining the mined out zones. Also most ore bodies are located where there has been a more than average amount of faulting, fracturing, and folding during the geologic past. They tend to cluster along crustal flows. In general, Precambrian rocks of similar geology, to those seen, well away from zones that have been disturbed by extensive deep mining, and well away from the zones of more intense geologic activity ought to be even less permeable than their equivalents in a mining district

  7. Vibracore, Radiocarbon, Microfossil, and Grain-Size Data from Apalachicola Bay, Florida

    Science.gov (United States)

    Twichell, D.C.; Pendleton, E.A.; Poore, R.Z.; Osterman, L.E.; Kelso, K.W.

    2009-01-01

    In 2007, the U.S. Geological Survey collected 24 vibracores within Apalachicola Bay, Florida. The vibracores were collected by using a Rossfelder electric percussive (P-3) vibracore system during a cruise on the Research Vessel (R/V) G.K. Gilbert. Selection of the core sites was based on a geophysical survey that was conducted during 2005 and 2006 in collaboration with the National Oceanic and Atmospheric Administration's (NOAA) Coastal Services Center (CSC) and the Apalachicola Bay National Estuarine Research Reserve. This report contains the vibracore data logs, photographs, and core-derived data including grain-size analyses, radiocarbon ages, microfossil counts, and sedimentological interpretations. The long-term goal of this study is to provide maps, data, and assistance to the Apalachicola Bay National Estuarine Research Reserve in their effort to monitor and understand the geology and ecology of Apalachicola Bay Estuary. These data will inform coastal managers charged with the responsibility for resource preservation.

  8. An Ecometric Study of Recent Microfossils using High-throughput Imaging

    Science.gov (United States)

    Elder, L. E.; Hull, P. M.; Hsiang, A. Y.; Kahanamoku, S.

    2016-02-01

    The era of Big Data has ushered in the potential to collect population level information in a manageable time frame. Taxon-free morphological trait analysis, referred to as ecometrics, can be used to examine and compare ecological dynamics between communities with entirely different species compositions. Until recently population level studies of morphology were difficult because of the time intensive task of collecting measurements. To overcome this, we implemented advances in imaging technology and created software to automate measurements. This high-throughput set of methods collects assemblage-scale data, with methods tuned to foraminiferal samples (e.g., light objects on a dark background). Methods include serial focused dark-field microscopy, custom software (Automorph) to batch process images, extract 2D and 3D shape parameters and frames, and implement landmark-free geometric morphometric analyses. Informatics pipelines were created to store, catalog and share images through the Yale Peabody Museum(YPM; peabody.yale.edu). We openly share software and images to enhance future data discovery. In less than a year we have generated over 25TB of high resolution semi 3D images for this initial study. Here, we take the first step towards developing ecometric approaches for open ocean microfossil communities with a calibration study of community shape in recent sediments. We will present an overview of the `shape' of modern planktonic foraminiferal communities from 25 Atlantic core top samples (23 sites in the North and Equatorial Atlantic; 2 sites in the South Atlantic). In total, more than 100,000 microfossils and fragments were imaged from these sites' sediment cores, an unprecedented morphometric sample set. Correlates of community shape, including diversity, temperature, and latitude, will be discussed. These methods have also been applied to images of limpets and fish teeth to date, and have the potential to be used on modern taxa to extract meaningful

  9. Precambrian uranium-bearing quartz-pebble conglomerates: exploration model and United States resource potential

    International Nuclear Information System (INIS)

    Houston, R.S.; Karlstrom, K.E.

    1979-11-01

    Uranium has been discovered in fluvial quartz-pebble conglomerates in most of the Precambrian shield areas of the world, including the Canadian, African, South American, Indian, Baltic, and Australian shields. Occurrences in these and other areas are shown. Two of these occurrences, the Huronian supergroup of Canada and the Witwatersrand deposit of South Africa contain 20 to 30 percent of the planet's known uranium reserves. Thus it is critical that we understand the origin of these deposits and develop exploration models that can aid in finding new deposits. Inasmuch as these uranium-bearing conglomerates are confined almost entirely to rocks of Precambrian age, Part I of this review begins with a discussion of Precambrian geology as it applies to the conglomerates. This is followed by a discussion of genetic concepts, a discussion of unresolved problems, and finally a suggested exploration model. Part II summarizes known and potential occurrences of Precambrian fossil placers in the world and evaluates them in terms of the suggested exploration model. Part III discusses the potential for important Precambrian fossil-placer uranium deposits in the United States and includes suggestions that may be helpful in establishing an exploration program in this country. Part III also brings together new (1975-1978) data on uranium occurrences in the Precambrian of the Wyoming Province. Part IV is a complete bibliography of Precambrian fossil placers, divided according to geographical areas. In total, this paper is designed to be a comprehensive review of Precambrian uranium-bearing fossil placers which will be of use to uranium explorationists and to students of Precambrian geology

  10. Precambrian uranium-bearing quartz-pebble conglomerates: exploration model and United States resource potential

    Energy Technology Data Exchange (ETDEWEB)

    Houston, R.S.; Karlstrom, K.E.

    1979-11-01

    Uranium has been discovered in fluvial quartz-pebble conglomerates in most of the Precambrian shield areas of the world, including the Canadian, African, South American, Indian, Baltic, and Australian shields. Occurrences in these and other areas are shown. Two of these occurrences, the Huronian supergroup of Canada and the Witwatersrand deposit of South Africa contain 20 to 30 percent of the planet's known uranium reserves. Thus it is critical that we understand the origin of these deposits and develop exploration models that can aid in finding new deposits. Inasmuch as these uranium-bearing conglomerates are confined almost entirely to rocks of Precambrian age, Part I of this review begins with a discussion of Precambrian geology as it applies to the conglomerates. This is followed by a discussion of genetic concepts, a discussion of unresolved problems, and finally a suggested exploration model. Part II summarizes known and potential occurrences of Precambrian fossil placers in the world and evaluates them in terms of the suggested exploration model. Part III discusses the potential for important Precambrian fossil-placer uranium deposits in the United States and includes suggestions that may be helpful in establishing an exploration program in this country. Part III also brings together new (1975-1978) data on uranium occurrences in the Precambrian of the Wyoming Province. Part IV is a complete bibliography of Precambrian fossil placers, divided according to geographical areas. In total, this paper is designed to be a comprehensive review of Precambrian uranium-bearing fossil placers which will be of use to uranium explorationists and to students of Precambrian geology.

  11. Uranium in Precambrian Moeda Formation, Minas Gerais, Brazil

    International Nuclear Information System (INIS)

    Villaca, J.N.; Moura, L.A.M.

    1981-01-01

    The Quadrilatero Ferrifero with an area of about 7000 km 2 is located south of Belo Horizonte in Minas Gerais, Brazil. Precambrian metaconglomerates (Proterozoic) of the Moeda Formation and Maquine Group are believed to be favorable host rocks for uranium deposits. Some areas are now being studied or have work planned for next year. Drilling succeeded in detecting at least three channels in different areas with ore-grade uranium-bearing oligomictic conglomerates. Reserve calculations require additional detailed work in those areas. Some models indicate that the sediments came from the Sao Francisco Craton, but paleocurrent directions in the Gandarela Syncline, as well as at Jacobina, indicate that the detritus came from the east, at least at these sites. This means that other cratonic areas must exist to the east of these outcrops. The Quadrilatero Ferrifero is mostly included between lat 19 0 45' and 20 0 30'S and long 43 0 22'30'' and 44 0 7'30'' W and lies near Belo Horizonte, Minas Gerais State, Brazil

  12. The Cottage Grove fault system (Illinois Basin): Late Paleozoic transpression along a Precambrian crustal boundary

    Science.gov (United States)

    Duchek, A.B.; McBride, J.H.; Nelson, W.J.; Leetaru, H.E.

    2004-01-01

    The Cottage Grove fault system in southern Illinois has long been interpreted as an intracratonic dextral strike-slip fault system. We investigated its structural geometry and kinematics in detail using (1) outcrop data, (2) extensive exposures in underground coal mines, (3) abundant borehole data, and (4) a network of industry seismic reflection profiles, including data reprocessed by us. Structural contour mapping delineates distinct monoclines, broad anticlines, and synclines that express Paleozoic-age deformation associated with strike slip along the fault system. As shown on seismic reflection profiles, prominent near-vertical faults that cut the entire Paleozoic section and basement-cover contact branch upward into outward-splaying, high-angle reverse faults. The master fault, sinuous along strike, is characterized along its length by an elongate anticline, ???3 km wide, that parallels the southern side of the master fault. These features signify that the overall kinematic regime was transpressional. Due to the absence of suitable piercing points, the amount of slip cannot be measured, but is constrained at less than 300 m near the ground surface. The Cottage Grove fault system apparently follows a Precambrian terrane boundary, as suggested by magnetic intensity data, the distribution of ultramafic igneous intrusions, and patterns of earthquake activity. The fault system was primarily active during the Alleghanian orogeny of Late Pennsylvanian and Early Permian time, when ultramatic igneous magma intruded along en echelon tensional fractures. ?? 2004 Geological Society of America.

  13. The precambrian of the Anti-Atlas (Morocco): a geochronological synthesis

    International Nuclear Information System (INIS)

    Charlot, Rene

    1976-01-01

    Twenty total-rock Rb/Sr isochrons (lambda 87 Rb=1.47x10 -11 yr 1 ) and many individual data, mainly obtained by the K/Ar and Rb/Sr methods, on total rocks and minerals show that the orogenic story of the Precambrian of the Anti-Atlas, which was studied in its western and central parts, began with the Eburnean orogeny (1900-1650 m.y.). Up to now there is no good evidence of an older basement, even if the rather high initial ratio (0.707-0.709) of some Eburnean granites might suggest that such a basement exists at depth. There is also no geochronological evidence of plutonism until in early Panafrican time (680 m.y.) there started a period of intense magmatic and thermal activity which was ended by the emplacement of late post-tectonic granites at 530-520 m.y. The late Panafrican acid volcanism does not generally give suitable material for Rb/Sr dating, because of the great mobility of the radiogenic strontium in such a material even under very weak thermal conditions

  14. Mineragraphic study of uraninites in precambrian quartzites of Kulu district, Himachal Pradesh, India

    International Nuclear Information System (INIS)

    Parthasarthy, T.N.

    1993-01-01

    Uraninites from the precambrian quartzites at Kandi-Panihar, Giagi-Khalandi, Dharagad-Bandal and Sajwar areas of Kulu district, Himachal Pradesh (Survey of India Sheet 53 E/NW) have been studied under ore-microscope and by X-ray diffraction. Besides uraninite, kasolite has also been identified occurring as oxidation product of the uraninite, and both occur filling up the macro- and micro-shear fractures developed in the quartzites. Uraninites show brecciation and recrystallization in these veins indicating that the mineralisation has been affected by a tectonic event. Two generations of uraninite have been noted in the veins. Later supergene alteration has resulted in the development of kasolite, curite, and wolsendorfite from the uraninite along the joint-planes. The only gangue mineral associated with the uraninite is quartz. Spectrographic data indicates that these uraninites are extremely poor in La and Ce compared to the hydrothermal uraninites reported from Singhbhum area of Bihar, India. In the light of the present studies it is difficult to comment on the genesis of Kulu uraninite at this stage, though X-ray powder data indicate high temperature origin for the early uraninite, with the unit cell size of around 5.4677A. (author). 19 refs., 4 tabs., 9 figs

  15. New Mesozoic and Cenozoic fossils from Ecuador: Invertebrates, vertebrates, plants, and microfossils

    Science.gov (United States)

    Cadena, Edwin A.; Mejia-Molina, Alejandra; Brito, Carla M.; Peñafiel, Sofia; Sanmartin, Kleber J.; Sarmiento, Luis B.

    2018-04-01

    Ecuador is well known for its extensive extant biodiversity, however, its paleobiodiversity is still poorly explored. Here we report seven new Mesozoic and Cenozoic fossil localities from the Pacific coast, inter-Andean depression and Napo basin of Ecuador, including vertebrates, invertebrates, plants, and microfossils. The first of these localities is called El Refugio, located near the small town of Chota, Imbabura Province, from where we report several morphotypes of fossil leaves and a mycetopodid freshwater mussel of the Upper Miocene Chota Formation. A second site is also located near the town of Chota, corresponding to potentially Pleistocene to Holocene lake deposits from which we report the occurrence of leaves and fossil diatoms. A third locality is at the Pacific coast of the country, near Rocafuerte, a town in Esmeraldas Province, from which we report a late Miocene palm leaf. We also report the first partially articulated skull with teeth from a Miocene scombridid (Mackerels) fish from El Cruce locality, and completely preserved seeds from La Pila locality, both sites from Manabí Province. Two late Cretaceous fossil sites from the Napo Province, one near Puerto Napo showing a good record of fossil shrimps and a second near the town of Loreto shows the occurrence of granular amber and small gymnosperms seeds and cuticles. All these new sites and fossils show the high potential of the sedimentary sequences and basins of Ecuador for paleontological studies and for a better understanding of the fossil record of the country and northern South America.

  16. Precambrian cyclic rhythmites: solar-climatic or tidal signatures?

    International Nuclear Information System (INIS)

    Williams, G.E.

    1990-01-01

    For more than 60 years geologists have sought evidence of solar-climatic cyclicity in rhythmically laminated sedimentary rocks, but claims in general have not been persuasive. Three Precambrian rhythmite sequences in Australia that comprise varve-like laminae recently have received attention, however, as their conspicuous cycles of ca. 10-14 and/or 20-25 laminae have been ascribed a sunspot-cycle origin. They are the 2500 Ma old Weeli Wolli Formation, the 1750 Ma old Wollogorang Formation and the 650 Ma old Elatina Formation. New observations for the Weeli Wolli Formation, a siliceous banded iron-formation, suggest a cycle period exceeding the 23 microband couplets proposed by Trendall, casting doubt on the solar interpretation. The Weeli Wolli cyclicity may record Earth-tidal rhythms that modulated the discharge and composition of silica- and iron-bearing fumarolic waters. The structure of the cycles of silty dolomite and mudstone in the Wollogorang Formation does not support a sunspot-cycle origin, and a tidal control on sedimentation should be considered. The Elatina sequence of cyclic sandstone and siltstone laminae displays several empirical similarities to the sunspot series. The discovery of thicker, more complex lamina-cycles in the correlative Reynella Siltstone has, however, caused reappraisal of the solar interpretation of the Elatina rhythmites. The Elatina series may encode unique information on lunar orbital periods and the Earth's palaeorotation: the data indicate ca. 30.5 days per lunar month, 13.1 lunar months and ca. 400 days per year, and lunar apsides and lunar nodal cycles of 9.7 and ca. 19.5 years respectively some 650 Ma ago. (author)

  17. Microfossils, biomolecules and biominerals in carbonaceous meteorites: implications to the origin of life

    Science.gov (United States)

    Hoover, Richard B.

    2012-11-01

    Environmental and Field Emission Scanning Electron Microscopy (ESEM and FESEM) investigations have shown that a wide variety of carbonaceous meteorites contain the remains of large filaments embedded within freshly fractured interior surfaces of the meteorite rock matrix. The filaments occur singly or in dense assemblages and mats and are often encased within carbon-rich, electron transparent sheaths. Electron Dispersive X-ray Spectroscopy (EDS) spot analysis and 2D X-Ray maps indicate the filaments rarely have detectable nitrogen levels and exhibit elemental compositions consistent with that interpretation that of the meteorite rock matrix. Many of the meteorite filaments are exceptionally well-preserved and show evidence of cells, cell-wall constrictions and specialized cells and processes for reproduction, nitrogen fixation, attachment and motility. Morphological and morphometric analyses permit many of the filaments to be associated with morphotypes of known genera and species of known filamentous trichomic prokaryotes (cyanobacteria and sulfur bacteria). The presence in carbonaceous meteorites of diagenetic breakdown products of chlorophyll (pristane and phytane) along with indigenous and extraterrestrial chiral protein amino acids, nucleobases and other life-critical biomolecules provides strong support to the hypothesis that these filaments represent the remains of cyanobacteria and other microorganisms that grew on the meteorite parent body. The absence of other life-critical biomolecules in the meteorites and the lack of detectable levels of nitrogen indicate the filaments died long ago and can not possibly represent modern microbial contaminants that entered the stones after they arrived on Earth. This paper presents new evidence for microfossils, biomolecules and biominerals in carbonaceous meteorites and considers the implications to some of the major hypotheses for the Origin of Life.

  18. A geological synthesis of the Precambrian shield in Madagascar

    Science.gov (United States)

    Tucker, Robert D.; Roig, J.Y.; Moine, B.; Delor, C.; Peters, S.G.

    2014-01-01

    Available U–Pb geochronology of the Precambrian shield of Madagascar is summarized and integrated into a synthesis of the region’s geological history. The shield is described in terms of six geodynamic domains, from northeast to southwest, the Bemarivo, Antongil–Masora, Antananarivo, Ikalamavony, Androyan–Anosyan, and Vohibory domains. Each domain is defined by distinctive suites of metaigneous rocks and metasedimentary groups, and a unique history of Archean (∼2.5 Ga) and Proterozoic (∼1.0 Ga, ∼0.80 Ga, and ∼0.55 Ga) reworking. Superimposed within and across these domains are scores of Neoproterozoic granitic stocks and batholiths as well as kilometer long zones of steeply dipping, highly strained rocks that record the effects of Gondwana’s amalgamation and shortening in latest Neoproterozoic time (0.560–0.520 Ga). The present-day shield of Madagascar is best viewed as part of the Greater Dharwar Craton, of Archean age, to which three exotic terranes were added in Proterozoic time. The domains in Madagascar representing the Greater Dharwar Craton include the Antongil–Masora domain, a fragment of the Western Dharwar of India, and the Neoarchean Antananarivo domain (with its Tsaratanana Complex) which is broadly analogous to the Eastern Dharwar of India. In its reconstructed position, the Greater Dharwar Craton consists of a central nucleus of Paleo-Mesoarchean age (>3.1 Ga), the combined Western Dharwar and Antongil–Masora domain, flanked by mostly juvenile “granite–greenstone belts” of Neoarchean age (2.70–2.56 Ga). The age of the accretionary event that formed this craton is approximately 2.5–2.45 Ga. The three domains in Madagascar exotic to the Greater Dharwar Craton are the Androyan–Anosyan, Vohibory, and Bemarivo. The basement to the Androyan–Anosyan domain is a continental terrane of Paleoproterozoic age (2.0–1.78 Ga) that was accreted to the southern margin (present-day direction) of the Greater Dharwar Craton in pre

  19. The contribution of the Precambrian continental lithosphere to global H2 production.

    Science.gov (United States)

    Lollar, Barbara Sherwood; Onstott, T C; Lacrampe-Couloume, G; Ballentine, C J

    2014-12-18

    Microbial ecosystems can be sustained by hydrogen gas (H2)-producing water-rock interactions in the Earth's subsurface and at deep ocean vents. Current estimates of global H2 production from the marine lithosphere by water-rock reactions (hydration) are in the range of 10(11) moles per year. Recent explorations of saline fracture waters in the Precambrian continental subsurface have identified environments as rich in H2 as hydrothermal vents and seafloor-spreading centres and have suggested a link between dissolved H2 and the radiolytic dissociation of water. However, extrapolation of a regional H2 flux based on the deep gold mines of the Witwatersrand basin in South Africa yields a contribution of the Precambrian lithosphere to global H2 production that was thought to be negligible (0.009 × 10(11) moles per year). Here we present a global compilation of published and new H2 concentration data obtained from Precambrian rocks and find that the H2 production potential of the Precambrian continental lithosphere has been underestimated. We suggest that this can be explained by a lack of consideration of additional H2-producing reactions, such as serpentinization, and the absence of appropriate scaling of H2 measurements from these environments to account for the fact that Precambrian crust represents over 70 per cent of global continental crust surface area. If H2 production via both radiolysis and hydration reactions is taken into account, our estimate of H2 production rates from the Precambrian continental lithosphere of 0.36-2.27 × 10(11) moles per year is comparable to estimates from marine systems.

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

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  1. Subsurface precambrian ridge on the continental shelf of western India between Coondapoor and Kasaragod

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, V.; Rao, M.G.; SubbaRaju, L.V.

    -positions of India which are sheared by the ENE-WSW fault F1 since its breakup from Africa. The interpreted (perhaps Precambrian), are of the same age or models are shown in Fig. 8. predates the fault F1. The reactivation of some of ~0 > > Z 3o' 73* 3d 7~ 31... type and Precambrian in age. ment ridge with the Prathap Ridge (Subrahmanyam, 1989) in the slope area further Acknowledgments north of the study area suggest that these two features probably evolved at the same period. The We thank Dr. B.N. Desai...

  2. Paleoproterozoic mojaveprovince in northwestern Mexico? Isotopic and U-Pb zircon geochronologic studies of precambrian and Cambrian crystalline and sedimentary rocks, Caborca, Sonora

    Science.gov (United States)

    Lang, Farmer G.; Bowring, S.A.; Matzel, J.; Maldonado, G.E.; Fedo, C.; Wooden, J.

    2005-01-01

    Whole-rock Nd isotopic data and U-Pb zircon geochronology from Precambrian crystalline rocks in the Caborca area, northern Sonora, reveal that these rocks are most likely a segment of the Paleoproterozoic Mojave province. Supporting this conclusion are the observations that paragneiss from the ??? 1.75 Ga Bamori Complex has a 2.4 Ga Nd model age and contains detrital zircons ranging in age from Paleo- proterozoic (1.75 Ga) to Archean (3.2 Ga). Paragneisses with similar age and isotopic characteristics occur in the Mojave province in southern California. In addition, "A-type" granite exposed at the southern end of Cerro Rajon has ca 2.0 Ga Nd model age and a U-Pb zircon age of 1.71 Ga, which are similar to those of Paleoproterozoic granites in the Mojave province. Unlike the U.S. Mojave province, the Caborcan crust contains ca. 1.1 Ga granite (Aibo Granite), which our new Nd isotopic data suggest is largely the product of anatexis of the local Precambrian basement. Detrital zircons from Neoproterozoic to early Cambrian miogeoclinal arenites at Caborca show dominant populations ca. 1.7 Ga, ca. 1.4 Ga, and ca. 1.1 Ga, with subordinate Early Cambrian and Archean zircons. These zircons were likely derived predominately from North American crust to the east and northeast, and not from the underlying Caborcan basement. The general age and isotopic similarities between Mojave province basement and overlying miogeoclinal sedimentary rocks in Sonora and southern California is necessary, but not sufficient, proof of the hypothesis that Sonoran crust is allochthonous and was transported to its current position during the Mesozoic along the proposed Mojave-Sonora megashear. One viable alternative model is that the Caborcan Precambrian crust is an isolated, autochthonous segment of Mojave province crust that shares a similar, but not identical, Proterozoic geological history with Mojave province crust found in the southwest United States ?? 2005 Geological Society of America.

  3. FACIES, MICROFOSSILS (SMALLER FORAMINIFERS, CALCAREOUS ALGAE AND BIOSTRATIGRAPHY OF THE HUECO GROUP, DOÑA ANA MOUNTAINS, SOUTHERN NEW MEXICO, USA

    Directory of Open Access Journals (Sweden)

    KARL KRAINER

    2009-03-01

    Full Text Available The Lower Permian Hueco Group of the Doña Ana Mountains (south-central New Mexico, USA is studied in three sections (A, B, C located east of Leasburg, Doña Ana County. Regionally, the Hueco Group has been subdivided into four formations termed Shalem Colony, Community Pit, Robledo Mountains and Apache Dam formations; the lower three are exposed in the Doña Ana Mountains. The succession shows a shallowing upward trend from dominantly shallow, open marine conditions (Shalem Colony Fm to increasingly restricted marine environments (Community Pit Fm and siliciclastic influx (Robledo Mountains Formation. Sedimentation, particularly siliciclastic influx, was mainly controlled by reactivation of basement uplifts during the last pulses of the Ancestral Rocky Mountains deformation. The microfossils and microfacies of the two first formations are studied in detail here. The Shalem Colony Formation can be divided into a lower biozone with Triticites pinguis, which is Newwellian (latest Pennsylvanian, early Wolfcampian in age, and an upper division characterized by the first occurrence of Geinitzina, and lower-middle Asselian (late early Wolfcampian in age. By comparison with the subdivisions of the Carnic Alps (Austria, the Community Pit Formation is characterized as Sakmarian (middle Wolfcampian in age due to the first occurrence of the genus Pseudovermiporella, and its probable complete phylogeny from Hedraites. The late Asselian is restricted to the uppermost part of the Shalem Colony and lowermost part of the Community Pit Formation. Due to the occurrence of Pseudoreichelina the Robledo Mountains Formation is dated as Artinskian (late Wolfcampian. Some bioconstructions of Archaeolithophyllum are emphasized, as well as some species of foraminifers-globivalvulinids, Miliolata and Nodosariata. 

  4. Geochemistry of Precambrian carbonatite complexes of India : present status of, and gaps in our knowledge

    Energy Technology Data Exchange (ETDEWEB)

    Udas, G R [Department of Atomic Energy, Hyderabad (India). Atomic Minerals Div.

    1974-01-01

    Carbonatites of Precambrian age occur at Newania and Mundwara in Rajasthan, Sevathur and Hogenakal in Tamil Nadu, Kunavaram in Andhra Pradesh, and Kollegal in Karnataka. The Newia carvonatite is 952 +- 24 m.v. old (K-Ar age of an alkali amplibole), and the Sevathur carbontite is 720 +- 30 m.y. old (K-Ar age of a biotite). Although comprehensive geochemical studies involving major, minor, and trace elements, and carbon, oxygen and strontium isotopes have been undertaken on the 37.5 +- 2.5 m.y. old Eocene carbonatite complex at Amba Dongar, Gujarat, geochemical studies on the Precambrian carbonatites of India have been confined only to routine determinations of selected elements like Sr, Ba, Y, Ce, La, Nb, Zr, Th, Mn, Ti, F and P to demonstrate their carbonatitic affinites. Except for two K-Ar ages, and for some limited trace element data, no attempts have been made to elucidate the chronologic and petrogenetic evolution of these Precambrian carbonatites by the application of Rb-Sr, K-Ar, and U-Pb geochronometry, critical element ratios, stable and radiogenic isotope abundances, and geothermometry. Basic researches aimed at formulating geochemical criteria for locating commercially exploitable economic Precambrian carbonatite complexes are yet to be initiated in India. (auth)

  5. The South India Precambrian crust and shallow lithospheric mantle ...

    Indian Academy of Sciences (India)

    term research project India Deep Earth Imaging ... standing of the early Earth. ..... only clear Ps. Red and blue circles denote the epicentral distance and backazimuth values for individual receiver ..... (red colour) in few stations in the MB/KKB.

  6. Stable isotope analysis of Dacryoconarid carbonate microfossils: a new tool for Devonian oxygen and carbon isotope stratigraphy.

    Science.gov (United States)

    Frappier, Amy Benoit; Lindemann, Richard H; Frappier, Brian R

    2015-04-30

    Dacryoconarids are extinct marine zooplankton known from abundant, globally distributed calcite microfossils in the Devonian, but their shell stable isotope composition has not been previously explored. Devonian stable isotope stratigraphy is currently limited to less common invertebrates or bulk rock analyses of uncertain provenance. As with Cenozoic planktonic foraminifera, isotopic analysis of dacryoconarid shells could facilitate higher-resolution, geographically widespread stable isotope records of paleoenvironmental change, including marine hypoxia events, climate changes, and biocrises. We explored the use of Dacryoconarid isotope stratigraphy as a viable method in interpreting paleoenvironments. We applied an established method for determining stable isotope ratios (δ(13) C, δ(18) O values) of small carbonate microfossils to very well-preserved dacryoconarid shells. We analyzed individual calcite shells representing five common genera using a Kiel carbonate device coupled to a MAT 253 isotope ratio mass spectrometer. Calcite shell δ(13) C and δ(18) O values were compared by taxonomic group, rock unit, and locality. Single dacryoconarid calcite shells are suitable for stable isotope analysis using a Kiel-IRMS setup. The dacryoconarid shell δ(13) C values (-4.7 to 2.3‰) and δ(18) O values (-10.3 to -4.8‰) were consistent across taxa, independent of shell size or part, but varied systematically through time. Lower fossil δ(18) O values were associated with warmer water temperature and more variable δ(13) C values were associated with major bioevents. Dacryoconarid δ(13) C and δ(18) O values differed from bulk rock carbonate values. Dacryoconarid individual microfossil δ(13) C and δ(18) O values are highly sensitive to paleoenvironmental changes, thus providing a promising avenue for stable isotope chemostratigraphy to better resolve regional to global paleoceanographic changes throughout the upper Silurian to the upper Devonian. Our results

  7. Control of Precambrian basement deformation zones on emplacement of the Laramide Boulder batholith and Butte mining district, Montana, United States

    Science.gov (United States)

    Berger, Byron R.; Hildenbrand, Thomas G.; O'Neill, J. Michael

    2011-01-01

    What are the roles of deep Precambrian basement deformation zones in the localization of subsequent shallow-crustal deformation zones and magmas? The Paleoproterozoic Great Falls tectonic zone and its included Boulder batholith (Montana, United States) provide an opportunity to examine the importance of inherited deformation fabrics in batholith emplacement and the localization of magmatic-hydrothermal mineral deposits. Northeast-trending deformation fabrics predominate in the Great Falls tectonic zone, which formed during the suturing of Paleoproterozoic and Archean cratonic masses approximately 1,800 mega-annum (Ma). Subsequent Mesoproterozoic to Neoproterozoic deformation fabrics trend northwest. Following Paleozoic through Early Cretaceous sedimentation, a Late Cretaceous fold-and-thrust belt with associated strike-slip faulting developed across the region, wherein some Proterozoic faults localized thrust faulting, while others were reactivated as strike-slip faults. The 81- to 76-Ma Boulder batholith was emplaced along the reactivated central Paleoproterozoic suture in the Great Falls tectonic zone. Early-stage Boulder batholith plutons were emplaced concurrent with east-directed thrust faulting and localized primarily by northwest-trending strike-slip and related faults. The late-stage Butte Quartz Monzonite pluton was localized in a northeast-trending pull-apart structure that formed behind the active thrust front and is axially symmetric across the underlying northeast-striking Paleoproterozoic fault zone, interpreted as a crustal suture. The modeling of potential-field geophysical data indicates that pull-apart?stage magmas fed into the structure through two funnel-shaped zones beneath the batholith. Renewed magmatic activity in the southern feeder from 66 to 64 Ma led to the formation of two small porphyry-style copper-molybdenum deposits and ensuing world-class polymetallic copper- and silver-bearing veins in the Butte mining district. Vein orientations

  8. From a collage of microplates to stable continental crust - an example from Precambrian Europe

    Science.gov (United States)

    Korja, Annakaisa

    2013-04-01

    Svecofennian orogen (2.0-1.7 Ga) comprises the oldest undispersed orogenic belt on Baltica and Eurasian plate. Svecofennian orogenic belt evolved from a series of short-lived terrane accretions around Baltica's Archean nucleus during the formation of the Precambrian Nuna supercontinent. Geological and geophysical datasets indicate W-SW growth of Baltica with NE-ward dipping subduction zones. The data suggest a long-lived retreating subduction system in the southwestern parts whereas in the northern and central parts the northeasterly transport of continental fragments or microplates towards the continental nucleus is also documented. The geotectonic environment resembles that of the early stages of the Alpine-Himalayan or Indonesian orogenic system, in which dispersed continental fragments, arcs and microplates have been attached to the Eurasian plate margin. Thus the Svecofennian orogeny can be viewed as proxy for the initial stages of an internal orogenic system. Svecofennian orogeny is a Paleoproterozoic analogue of an evolved orogenic system where terrane accretion is followed by lateral spreading or collapse induced by change in the plate architecture. The exposed parts are composed of granitoid intrusions as well as highly deformed supracrustal units. Supracrustal rocks have been metamorphosed in LP-HT conditions in either paleo-lower-upper crust or paleo-upper-middle crust. Large scale seismic reflection profiles (BABEL and FIRE) across Baltica image the crust as a collage of terranes suggesting that the bedrock has been formed and thickened in sequential accretions. The profiles also image three fold layering of the thickened crust (>55 km) to transect old terrane boundaries, suggesting that the over-thickened bedrock structures have been rearranged in post-collisional spreading and/or collapse processes. The middle crust displays typical large scale flow structures: herringbone and anticlinal ramps, rooted onto large scale listric surfaces also suggestive

  9. SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions

    Science.gov (United States)

    Schopf, J. William; Kitajima, Kouki; Spicuzza, Michael J.; Kudryavtsev, Anatoliy B.; Valley, John W.

    2018-01-01

    Analyses by secondary ion mass spectroscopy (SIMS) of 11 specimens of five taxa of prokaryotic filamentous kerogenous cellular microfossils permineralized in a petrographic thin section of the ˜3,465 Ma Apex chert of northwestern Western Australia, prepared from the same rock sample from which this earliest known assemblage of cellular fossils was described more than two decades ago, show their δ13C compositions to vary systematically taxon to taxon from ‑31‰ to ‑39‰. These morphospecies-correlated carbon isotope compositions confirm the biogenicity of the Apex fossils and validate their morphology-based taxonomic assignments. Perhaps most significantly, the δ13C values of each of the five taxa are lower than those of bulk samples of Apex kerogen (‑27‰), those of SIMS-measured fossil-associated dispersed particulate kerogen (‑27.6‰), and those typical of modern prokaryotic phototrophs (‑25 ± 10‰). The SIMS data for the two highest δ13C Apex taxa are consistent with those of extant phototrophic bacteria; those for a somewhat lower δ13C taxon, with nonbacterial methane-producing Archaea; and those for the two lowest δ13C taxa, with methane-metabolizing γ-proteobacteria. Although the existence of both methanogens and methanotrophs has been inferred from bulk analyses of the carbon isotopic compositions of pre-2,500 Ma kerogens, these in situ SIMS analyses of individual microfossils present data interpretable as evidencing the cellular preservation of such microorganisms and are consistent with the near-basal position of the Archaea in rRNA phylogenies.

  10. SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions.

    Science.gov (United States)

    Schopf, J William; Kitajima, Kouki; Spicuzza, Michael J; Kudryavtsev, Anatoliy B; Valley, John W

    2018-01-02

    Analyses by secondary ion mass spectroscopy (SIMS) of 11 specimens of five taxa of prokaryotic filamentous kerogenous cellular microfossils permineralized in a petrographic thin section of the ∼3,465 Ma Apex chert of northwestern Western Australia, prepared from the same rock sample from which this earliest known assemblage of cellular fossils was described more than two decades ago, show their δ 13 C compositions to vary systematically taxon to taxon from -31‰ to -39‰. These morphospecies-correlated carbon isotope compositions confirm the biogenicity of the Apex fossils and validate their morphology-based taxonomic assignments. Perhaps most significantly, the δ 13 C values of each of the five taxa are lower than those of bulk samples of Apex kerogen (-27‰), those of SIMS-measured fossil-associated dispersed particulate kerogen (-27.6‰), and those typical of modern prokaryotic phototrophs (-25 ± 10‰). The SIMS data for the two highest δ 13 C Apex taxa are consistent with those of extant phototrophic bacteria; those for a somewhat lower δ 13 C taxon, with nonbacterial methane-producing Archaea; and those for the two lowest δ 13 C taxa, with methane-metabolizing γ-proteobacteria. Although the existence of both methanogens and methanotrophs has been inferred from bulk analyses of the carbon isotopic compositions of pre-2,500 Ma kerogens, these in situ SIMS analyses of individual microfossils present data interpretable as evidencing the cellular preservation of such microorganisms and are consistent with the near-basal position of the Archaea in rRNA phylogenies.

  11. Diamond drilling for geologic information in the middle Precambrian basins in the western portion of northern Michigan. Final report

    International Nuclear Information System (INIS)

    Trow, J.

    1979-10-01

    Between September 26, 1977, and May 11, 1978, six initially vertical holes probed a total of 9896 feet (1109 feet or 11.2% in overburden, 155 feet or 1.6% in Precambrian Y mafic dikes, 8386 feet or 84.7% in Precambrian X Goodrich Quartzite and Michigamme Formation, and 246 feet or 2.5% in Precambrian W basement lithologies). In addition to normal examination of core, logging, and storing of core, the holes were extensively logged geophysically, acidized core was tested for phosphate content by ammonium molybdate, splits from five out of every thirty feet of core were subjected to chemical scrutiny, thin sections of all lithologies were examined, and radiometric determinations of geologic age were made for confirmation of Precambrian W basement which was encountered in each of the three basins in Marquette County

  12. Application of carbon and oxygen stable isotopes to the study of Brazilian precambrian

    International Nuclear Information System (INIS)

    Torquato, J.R.F.

    1980-01-01

    Samples of carbonated rocks of precambrian age are studied. The stable carbon and oxygen isotopes are applied to the study of terrestrial materials considering the variations of some element isotopic composition in function of the environment of sedimentation. The isotopic analysis was done using mass spectrometers. The analytical results and the description of region geology of the site of each sample are presented. The isotopic data are interpreted aiming to the environment of sedimentation. New techniques for better improvement of carbon and oxygen ratios, are proposed, such as: to use the analysis of surface trend and the isotopic logging in mapping of surface and subsurface. A new method for approximated determination of the ages of precambrian carbonated rocks, considering the limitations of their new technique, is also presented. (M.C.K.) [pt

  13. A contribution to the subdivision of the precambrian in South America

    International Nuclear Information System (INIS)

    Brito Neves, B.B. de; Teixeira, W.; Tassinari, C.C.G.; Kawashita, K.

    1990-01-01

    On the shield areas of the South America continent (about 5,000,000 km 2 large) there are about 17,000 geochronological determinations available. More than 75% of this amount has been carried out in the Centro de Pesquisas Geocronologicas da Universidade de Sao Paulo, CPGeo-USP, in the last 25 years. The majority of these data were accomplished through Rb-Sr (ca.60%) and K-Ar (ca.40%) methods. The author tried to work this amount of data on a coherent way according to the progress observed in the geologic and geotectonic knowledge during the last two decades. One of the fundamental goals was to outline an up-to-date subdivision for the Precambrian of this continent, having in mind a contribution to the International Commission on Stratigraphy (ICS), Subcommission of Precambrian Stratigraphy (SPS) of the IUGS. (author)

  14. Isotopic fractionation between organic carbon and carbonate carbon in Precambrian banded ironstone series from Brazil

    International Nuclear Information System (INIS)

    Schidlowski, M.; Eichmann, R.; Fiebiger, W.

    1976-01-01

    37 delta 13 Csub(org) and 9 delta 13 Csub(carb) values furnished by argillaceous and carbonate sediments from the Rio das Velhas and Minas Series (Minas Gerais, Brazil) have yielded means of -24.3 +- 3.9 promille [PDB] and -0.9 +- 1.4 promille [PDB], respectively. These results, obtained from a major sedimentary banded ironstone province with an age between 2 and 3 x 10 9 yr, support previous assumptions that isotopic fractionation between inorganic and organic carbon in Precambrian sediments is about the same as in Phanerozoic rocks. This is consistent with a theoretically expected constancy of the kinetic fractionation factor governing biological carbon fixation and, likewise, with a photosynthetic pedigree of the reduced carbon fraction of Precambrian rocks. (orig.) [de

  15. Soil stabilization by a prokaryotic desert crust - Implications for Precambrian land biota

    Science.gov (United States)

    Campbell, S. E.

    1979-01-01

    The ecology of the cyanophyte-dominated stromatolitic mat forming the ground cover over desert areas of Utah and Colorado is investigated and implications for the formation of mature Precambrian soils are discussed. The activation of the growth of the two species of filamentous cyanophyte identified and the mobility of their multiple trichromes upon wetting are observed, accompanied by the production and deposition of a sheath capable of accreting and stabilizing sand and clay particles. The formation of calcium carbonate precipitates upon the repeated wetting and drying of desert crust is noted, and it is suggested that the desert crust community may appear in fossil calcrete deposits as lithified microscopic tubes and cellular remains of algal trichromes. The invasion of dry land by both marine and freshwater algae on the model of the desert crust is proposed to be responsible for the accumulation, stabilization and biogenic modification of mature Precambrian soils.

  16. Variation of stable silicon isotopes. Analytical developments and applications in Precambrian geochemistry

    International Nuclear Information System (INIS)

    Abraham, Kathrin

    2010-01-01

    The work presented in this thesis predominantly deals with bulk-rock measurements of silicon stable isotopes on a Multi Collector-ICP-MS. Analyses were performed in cooperation with the Royal Museum for Central Africa, Belgium. The first section describes how the first analysis of δ 30 Si on a conventional Nu PlasmaTM Multi-Collector ICP-MS instrument can be enabled by the elimination of 14N16O interference overlying the 30Si peak. The determination of δ 30 Si was rendered possible owing to new instrumental upgrades that facilitate the application of a higher mass resolution. The careful characterisation of appropriate reference materials is indispensable for the assessment of the accuracy of a measurement. The determination of U.S. Geological Survey (USGS) reference materials represents the second objective of this section. The analysis of two Hawaiian standards (BHVO-1 and BHVO-2) demonstrates precise and accurate δ 30 Si determinations and provides cross-calibration data as a quality control for other laboratories. The second section focuses on coupled silicon-oxygen isotopic evidences for the origin of silicification in mafic volcanic rocks of the Barberton Greenstone Belt, South Africa. In contrast to the modern Earth, silicification of near-surface layers, including chert formation, were widespread processes on the Precambrian ocean floor, and demonstrate the ubiquity of extreme silica mobilization in the early Earth. This section outlines the investigation of silicon and oxygen isotopes on three different stratigraphic sections of variably silicified basalts and overlying bedded cherts from the 3.54 Ga, 3.45 Ga and 3.33 Ga Theespruit, Kromberg and Hooggenoeg Formations, respectively. Silicon isotopes, oxygen isotopes and the variable SiO 2 -contents demonstrate a positive correlation with silicification intensity in all three sections, with varying gradients of δ 30 Si vs. δ 18 O arrays for different sections. Seawater has been regarded as the most

  17. Variation of stable silicon isotopes. Analytical developments and applications in Precambrian geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, Kathrin

    2010-05-28

    The work presented in this thesis predominantly deals with bulk-rock measurements of silicon stable isotopes on a Multi Collector-ICP-MS. Analyses were performed in cooperation with the Royal Museum for Central Africa, Belgium. The first section describes how the first analysis of δ{sup 30}Si on a conventional Nu PlasmaTM Multi-Collector ICP-MS instrument can be enabled by the elimination of 14N16O interference overlying the 30Si peak. The determination of δ{sup 30}Si was rendered possible owing to new instrumental upgrades that facilitate the application of a higher mass resolution. The careful characterisation of appropriate reference materials is indispensable for the assessment of the accuracy of a measurement. The determination of U.S. Geological Survey (USGS) reference materials represents the second objective of this section. The analysis of two Hawaiian standards (BHVO-1 and BHVO-2) demonstrates precise and accurate δ{sup 30}Si determinations and provides cross-calibration data as a quality control for other laboratories. The second section focuses on coupled silicon-oxygen isotopic evidences for the origin of silicification in mafic volcanic rocks of the Barberton Greenstone Belt, South Africa. In contrast to the modern Earth, silicification of near-surface layers, including chert formation, were widespread processes on the Precambrian ocean floor, and demonstrate the ubiquity of extreme silica mobilization in the early Earth. This section outlines the investigation of silicon and oxygen isotopes on three different stratigraphic sections of variably silicified basalts and overlying bedded cherts from the 3.54 Ga, 3.45 Ga and 3.33 Ga Theespruit, Kromberg and Hooggenoeg Formations, respectively. Silicon isotopes, oxygen isotopes and the variable SiO{sub 2}-contents demonstrate a positive correlation with silicification intensity in all three sections, with varying gradients of δ{sup 30}Si vs. δ{sup 18}O arrays for different sections. Seawater has been

  18. Precambrian large igneous provinces: an overview of geochronology, origins and impact on earth evolution

    International Nuclear Information System (INIS)

    Heaman, Larry M.

    2008-01-01

    Precambrian large igneous provinces flourished during the Proterozoic and some, such as the 1.27 Ga Mackenzie event in North America, resemble their Phanerozoic counterparts with good evidence for the production of large volumes of mafic magma in short periods of geologic time (<10 m.y.), a specific focus of this magmatism, and regional uplift prior to the onset of volcanism. In many Precambrian examples, the flood basalts have been largely removed by erosion and only the root zone (e.g. dyke swarm, layered mafic intrusion) of these large igneous provinces is preserved. The short duration of this magmatism and the geometric relationship between linear dyke swarms and basement geology can potentially provide a robust geological pin in continental reconstructions. The extensive 2.37 Ga E-W trending Bangalore dyke swarm in the Dharwar craton, India cross-cuts N-S trending Neoarchean greenstone belts and the 2.51 Ga Closepet granite and is a good example of the potential for providing a cornerstone in Paleoproterozoic continent reconstruction. In contrast, the 1.89 Ga Southern Bastar-Cuddapah large igneous province in southern India is one of several large igneous provinces formed at this time on different continents, including the 1.89-1.88 Ga circum-Superior mafic/ultramafic magmatism in North America and the 1.88-1.87 Ga Waterberg Group sills in South Africa, and is part of a global period of enhanced mantle melting. A challenge for future attempts at Precambrian continent reconstruction is to distinguish between discrete global periods of enhanced mantle melting and a single specific focus large igneous province. (author)

  19. Radioactivity and decay heat generation in precambrian magmatic rocks (with the South Pamirs as an example)

    International Nuclear Information System (INIS)

    Batyrmurzaev, A.S.; Alibekov, G.I.; Bekieva, A.A.

    2003-01-01

    The evaluation of the heat generation share in the results of the long-living radioactive elements (RAE) decay in the Earth surface layers is accomplished on the basis of the data on the uranium and thorium concentration in the precambrian magmatic rocks of the South Pamirs. It was supposed by the calculations, that the value of the heat flux, generated by the rocks, is determined mainly by the RAE content in the Earth upper layer crust itself of 10-15 km. It is shown that the radioheat generation share is within the range of 5-10% from the measured values of the geothermal flows [ru

  20. Reactivation of precambrian faults on the southwestern continental margin of India: Evidence from gravity anomalies

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, V.; Ramana, M.V.; Rao, D.G.

    con- fi~ration of the western continental margin, with various structural styles, has been considered as a single unit, even though there exists a difference of opinion about the origin and evolution of the Chagos-Laccadive Ridge complex...’tVATION OF PRECAMBRIAN FAULTS ON THE SW CON~~E~AL MARGIN OF INDIA 337 shelf break due to the steep topographic relief of shelf. Furthermore, the gradients might have played a dominant role in shaping the bathymetry when the block movement took place along the pre...

  1. Principal types of precambrian uranium-gold deposits and their metallogenetic characteristics in China

    International Nuclear Information System (INIS)

    Liang Liang; Zhong Zhiyun.

    1988-01-01

    Principal types of Precambrian uranium-gold deposits are follows: paleo-conglomerate uranium-deposit, stratified or strata-bound uranium-gold deposit, unconformity-related uranium deposit (no or seldem gold) and greenstone gold deposit. The main types of gold deposits in China is greenstone one which is characterized by later age, high grade metamorphism and a large time difference between diagenesis of host rocks and gold metallogenesis. Gold deposits are spatially distributed in the uplift area, whereas uranium deposits are distributed in the downfaulted belt. Furthermore, both uranium and gold deposits are controlled by regional fractures

  2. Geochronological correlation of the late Precambrian sequences on and around the stable zones of Equatorial Africa

    International Nuclear Information System (INIS)

    Cahen, L.

    1982-01-01

    Very few radiometric age determinations have a bearing on the late Precambrian sequences of the stable zones of Equatorial Africa. A geochronological correlation of these sequences must therefore rest upon a compilation of ages from these stable zones and the corresponding mobile zones. About 15 ages of varying precision more or less well tied up with the stratigraphical sequences, together with results of the study of stromatolite assemblages allow a provisional correlation to be made. One conclusion of this correlation is that most mixtites surrounding the Congo basin are in a 950 +- 50 Ma age bracket and are presumably to be correlated. (Auth.)

  3. Did opening of the South China Sea impact development of the Asian Monsoon? Results from Oligocene microfossils, IODP Site U1435, northern South China Sea

    Science.gov (United States)

    Kulhanek, Denise K.; Su, Xin; Li, Qianyu; Gregory, Mitch; Warny, Sophie; Clift, Peter D.

    2016-04-01

    Development of the Asian Monsoon is linked to uplift of the Himalayas and Tibetan Plateau in the Cenozoic, with good evidence for a strong monsoon system by the late Oligocene to early Miocene (e.g., Guo et al., 2002; Clift et al., 2008). However, Licht et al. (2014) suggested the presence of an Asian Monsoon in the late Eocene. Recent scientific ocean drilling in the Indian Ocean and surrounding marginal seas gives us the opportunity to test this hypothesis with newly recovered Paleogene sediment cores. International Ocean Discovery Program Expedition 349 to the South China Sea recovered a 30 m section of primarily lower Oligocene nannofossil-rich claystone at Site U1435, located near the northern continent/ocean boundary. A thick sandstone unit devoid of typical marine microfossils underlies the marine claystone. The sandstone is interpreted as a deltaic or restricted marine deposit and is dated to the Eocene based on the presence of organic-walled palynomorphs, suggesting that a hiatus of several million years likely separates the sandstone below from the Oligocene marine claystone. This hiatus is interpreted as the breakup unconformity, with paleodepths in the South China Sea increasing during the Oligocene. Thus, this claystone should record if opening of the South China Sea during the early Oligocene influenced development of the Asian Monsoon. Combined calcareous nannofossil and planktonic foraminifer biostratigraphy indicates that the 30 m section is primarily early Oligocene in age (~33.5-30 Ma) and was deposited on the middle slope, with paleodepths >500 m. Stable oxygen isotopes from planktonic foraminifers become heavier up-hole, suggestive of cooling/deepening in the region, whereas carbon isotopes record variable conditions with no distinct maxima or minima. Calcareous nannoplankton primarily live in the upper 50 m of the ocean and are sensitive to sea-surface temperature and nutrient conditions, thus making them useful recorders of paleoceanographic

  4. National Uranium Resource Evaluation. Volume 1. Summary of the geology and uranium potential of Precambrian conglomerates in southeastern Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Karlstrom, K.E.; Houston, R.S.; Flurkey, A.J.; Coolidge, C.M.; Kratochvil, A.L.; Sever, C.K.

    1981-02-01

    A series of uranium-, thorium-, and gold-bearing conglomerates in Late Archean and Early Proterozoic metasedimentary rocks have been discovered in southern Wyoming. The mineral deposits were found by applying the time and strata bound model for the origin of uranium-bearing quartz-pebble conglomerates to favorable rock types within a geologic terrane known from prior regional mapping. No mineral deposits have been discovered that are of current (1981) economic interest, but preliminary resource estimates indicate that over 3418 tons of uranium and over 1996 tons of thorium are present in the Medicine Bow Mountains and that over 440 tons of uranium and 6350 tons of thorium are present in Sierra Madre. Sampling has been inadequate to determine gold resources. High grade uranium deposits have not been detected by work to date but local beds of uranium-bearing conglomerate contain as much as 1380 ppM uranium over a thickness of 0.65 meters. This project has involved geologic mapping at scales from 1/6000 to 1/50,000 detailed sampling, and the evaluation of 48 diamond drill holes, but the area is too large to fully establish the economic potential with the present information. This first volume summarizes the geologic setting and geologic and geochemical characteristics of the uranium-bearing conglomerates. Volume 2 contains supporting geochemical data, lithologic logs from 48 drill holes in Precambrian rocks, and drill site geologic maps and cross-sections from most of the holes. Volume 3 is a geostatistical resource estimate of uranium and thorium in quartz-pebble conglomerates.

  5. National Uranium Resource Evaluation. Volume 1. Summary of the geology and uranium potential of Precambrian conglomerates in southeastern Wyoming

    International Nuclear Information System (INIS)

    Karlstrom, K.E.; Houston, R.S.; Flurkey, A.J.; Coolidge, C.M.; Kratochvil, A.L.; Sever, C.K.

    1981-02-01

    A series of uranium-, thorium-, and gold-bearing conglomerates in Late Archean and Early Proterozoic metasedimentary rocks have been discovered in southern Wyoming. The mineral deposits were found by applying the time and strata bound model for the origin of uranium-bearing quartz-pebble conglomerates to favorable rock types within a geologic terrane known from prior regional mapping. No mineral deposits have been discovered that are of current (1981) economic interest, but preliminary resource estimates indicate that over 3418 tons of uranium and over 1996 tons of thorium are present in the Medicine Bow Mountains and that over 440 tons of uranium and 6350 tons of thorium are present in Sierra Madre. Sampling has been inadequate to determine gold resources. High grade uranium deposits have not been detected by work to date but local beds of uranium-bearing conglomerate contain as much as 1380 ppM uranium over a thickness of 0.65 meters. This project has involved geologic mapping at scales from 1/6000 to 1/50,000 detailed sampling, and the evaluation of 48 diamond drill holes, but the area is too large to fully establish the economic potential with the present information. This first volume summarizes the geologic setting and geologic and geochemical characteristics of the uranium-bearing conglomerates. Volume 2 contains supporting geochemical data, lithologic logs from 48 drill holes in Precambrian rocks, and drill site geologic maps and cross-sections from most of the holes. Volume 3 is a geostatistical resource estimate of uranium and thorium in quartz-pebble conglomerates

  6. Origin and microfossils of the oil shale of the Green River Formation of Colorado and Utah

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, W.H.

    1931-01-01

    The Green River formation of Colorado and Utah is a series of lakebeds of middle Eocene age that occupy two broad, shallow, simple, structural basins, the Piceance Creek basin in northwestern Colorado and the Uinta basin in northwestern Utah. The ancient lakes apparently were shallow and had a large area, compared with depth. The abundance of organisms and the decaying organic matter produced a strongly reducing environment. Mechanical and chemical action, such as the mastication and digestion of the organic material by bottom-living organisms, caused disintegration of the original organic matter. After most of the oil shale was deposited, the lake reverted nearly to the conditions that prevailed during its early stage, when the marlstone and low-grade oil shale of the basal member were formed. Microgranular calcite and dolomite are the predominant mineral constituents of most of the oil shale. The microflora of the Green River formation consist of two forms that have been referred to as bacteria and many fungi spores. Two kinds of organic matter are seen in thin sections of the oil shale; one is massive and structureless and is the matrix of the other, which has definite form and consists of organisms or fragments of organisms. Most structureless organic matter is isotropic (there are two anisotropic varieties) and makes up the greater part of the total organic material.

  7. Four magnetite generations in the Precambrian Varena Iron Ore deposit, SE Lithuania, as a result of rock-fluid interactions

    Science.gov (United States)

    Skridlaite, Grazina; Prusinskiene, Sabina; Siliauskas, Laurynas

    2017-04-01

    Iron ores in Precambrian crystalline basement of the Varena area, SE Lithuania, were discovered during the detail geological-geophysical exploration in 1982-1992. They are covered with 210-500 m thick sediments. The Varena Iron Ore deposit (VIOD) may yield from 71 to 219.6 million tons of iron ore according to different economic evaluations (Marfin, 1996). They were assumed to be of metasomatic and hydrothermal origin, however several other hypotheses explaining the VIOZ origin, e.g. as a layered mafic or carbonatite intrusions were also suggested. Magnetites of the VIOD were thoroughly investigated by the Cameca SX100 microprobe at the Warsaw University and by the Quanta 250 Energy Dispersive Spectroscopy (EDS) at the Nature Research Centre in Vilnius, Lithuania. Four generations of magnetite were distinguished in the studied serpentine-magnetite ores (D8 drilling) and were compared with the earlier studied and reference magnetites. The earliest, spinel inclusion-rich magnetite cores (Mag-1) have the highest trace element contents (in wt%): Si (0.032), Al (0.167-0.248), Mg (0.340-0.405), Ti (0.215-0.254), V (0.090-0.138) etc. They might have formed during an early metamorphism and/or related skarn formation. Voluminous second magnetite (Mag-2) replacing olivine, pyroxenes, spinel and other skarn minerals at c. 540o C (Magnetite-Ilmenite geothermometer) has much lower trace element abundances, probably washed out by hydrothermal fluids. The latest magnetites (Mag-3 and Mag-4) overgrow the earlier ones and occur near or within the sulfide veins (Mag-4). As was observed from microtextures, the Mag-3 and Mag-4 have originated from the late thermal reworking by dissolution-reprecipitation processes. To imply an origin of the studied magnetites, they were compared to the earlier studied magmatic-metamorphic (1058 drilling), presumably skarn (982 drilling) magnetites from the studied area and plotted in the major magnetite ore type fields according to Dupuis and Beaudoin

  8. Origin and microfossils of the oil shale of the Green River formation of Colorado and Utah

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, W.H.

    1931-01-01

    The Green River formation of Colorado and Utah is a series of lakebeds of middle Eocene age that occupy two broad, shallow, simple, structural basins--the Piceance Creek basin in northwestern Colorado and the Uinta basin in northeastern Utah. The ancient lakes served as a basin for the accumulation of tremendous quantities of aquatic organisms. The predominance of microscopic fresh-water algae and protozoa over the remains of land plants, pollens and spores suggests that the greater part of the organic matter was derived from microorganisms that grew in the lakes. The pollens and spores were carried into the lakes by wind. Fish, mollusks, crustaceans, and aquatic insect larvae were also plentiful; and turtles, crocodiles, birds, small camels, and insects may have contributed to the organic matter. The ancient lakes apparently were shallow and had a large area, compared with depth. The abundance of organisms and the decaying organic matter produced a strongly reducing environment. Mechanical and chemical action, such as the mastication and digestion of the organic material by bottom-living organisms, caused disintegration of the original organic matter. When the residue was reduced to a gelatinous condition, it apparently resisted further bacterial decay, and other organisms accidently entombed in the gel were protected from disintegration. An accumulation of inorganic material occurred simultaneously with the disintegration of the organic ooze, and the entire mass became lithified. After most of the oil shale was deposited, the lake reverted nearly to the conditions that prevailed during its early stage, when the marlstone and low-grade oil shale of the basal member were formed. The streams in the vicinity of the lake were rejuvenated and carried great quantities of medium- to coarse-grained sand into the basin and formed a thick layer over the lakebeds.

  9. Rb-Sr ages of Precambrian sediments from the Ovruch mountain range, northwestern Ukraine (U.S.S.R.)

    International Nuclear Information System (INIS)

    Gorokhov, I.M.; Varshavskaya, E.S.; Kutyavin, E.P.; Clauer, N.; Drannik, A.S.

    1981-01-01

    A mineralogical and Rb-Sr geochronological study of Precambrian sediments and metasediments from the Ovruch mountain range (northwestern Ukraine) shows two distinct events: a slight metamorphism of the Belokorovichi Formation 1575 +- 30 Ma ago which precedes the deposition of the Zbranki Formation at 1389 +- 71 Ma (lambda 87 Rb = 1.42 x 10 -11 y -1 ). (Auth.)

  10. Stratigraphic and microfossil evidence for hydroclimate changes over the middle to late Holocene in the northern Bahamas from an inland saline lake

    Science.gov (United States)

    van Hengstum, P. J.; Maale, G. E.; Donnelly, J. P.; Onac, B. P.; Sullivan, R.; Winkler, T. S.; Albury, N. A.

    2016-12-01

    No Man's Land is one of the largest inland lakes on the Little Bahama Bank in the northern Bahamas, so its paleoenvironmental history may provide insight into how the regional hydroclimate developed over the Holocene. In its modern state, the site is shallow (aquatic invertebrates (e.g., ostracodes, foraminifera, aquatic mollusks) indicate that the site was a terrestrial ecosystem. However, the site transitioned into a subaqueous freshwater environment at 6400 Cal yrs BP, and the site became a palustrine-lacustrine setting thereafter until 4200 Cal yrs BP. During this time, widespread palustrine-lacustrine carbonate deposition and the appearance of freshwater to low mesohaline microfossils indicates that the lake's salinity was likely oligohaline (charophytes, ostracodes: Candona annae, Cypridopsis vidua, foraminifera: Helenina davescottensis, mollusks: Planorbis, Hydrobia). A salinity increase at 4200 Cal yrs BP is inferred from the appearance of the ostracode Cyprideis americana that typically prefers salinities exceeding 10 psu, and deposition of laminated microbial mats. Thereafter, an organic- rich, algal sapropel unit accumulated that was devoid of any microfossils or mollusks. This unit suggests that the lake hosted a stratified water column, where surface waters supported phytoplankton primary productivity and corrosive or anoxic bottom water conditions either hampered microfossil growth or precluded their preservation. The transition to the modern environment ( 20 psu) at 2600 cal yrs BP is characterized by diversification of brackish ostracodes (Aurila floridana, Dolerocypria inopinata, and Hemicyprideis setipunctata), foraminifera (Elphidium spp., Ammonia beccarii, Triloculina oblonga) and mollusks (Anomalocardia, Cerithidea). Over the middle to late Holocene, it appears that the stratigraphic development and salinity changes in No Man's Land has been driven by groundwater-level rise in response to Holocene sea-level rise, the regional delivery of fresh

  11. Precambrian evolution of the Salalah Crystalline Basement from structural analysis and 40Ar/39Ar geochronology

    Science.gov (United States)

    Al-Doukhi, Hanadi Abulateef

    The Salalah Crystalline Basement (SCB) is the largest Precambrian exposure in Oman located on the southern margin of the Arabian Plate at the Arabian Sea shore. This work used remote sensing, detailed structural analysis and the analysis of ten samples using 40Ar/39Ar age dating to establish the Precambrian evolution of the SCB by focusing on its central and southwestern parts. This work found that the SCB evolved through four deformational events that shaped its final architecture: (1) Folding and thrusting event that resulted in the emplacement of the Sadh complex atop the Juffa complex. This event resulted in the formation of possibly N-verging nappe structure; (2) Regional folding event around SE- and SW-plunging axes that deformed the regional fabric developed during the N-verging nappe structure and produced map-scale SE- and SW-plunging antiforms shaping the complexes into a semi-dome structure; (3) Strike-slip shearing event that produced a conjugate set of NE-trending sinistral and NW-trending dextral strike-slip shear zones; and (4) Localized SE-directed gravitational collapse manifested by top-to-the-southeast kinematic indicators. Deformation within the SCB might have ceased by 752.2+/-2.7 Ma as indicated by an age given by an undeformed granite. The thermochron of samples collected throughout the SCB complexes shows a single cooling event that occurred between about 800 and 760 Ma. This cooling event could be accomplished by crustal exhumation resulting in regional collapse following the prolonged period of the contractional deformation of the SCB. This makes the SCB a possible metamorphic core complex.

  12. Precambrian Field Camp at the University of Minnesota Duluth - Teaching Skills Applicable to Mapping Glaciated Terranes of the Canadian Shield

    Science.gov (United States)

    Miller, J. D.; Hudak, G. J.; Peterson, D.

    2011-12-01

    Since 2007, the central program of the Precambrian Research Center (PRC) at the University of Minnesota Duluth has been a six-week geology field camp focused on the Precambrian geology of the Canadian Shield. This field camp has two main purposes. First and foremost is to teach students specialized field skills and field mapping techniques that can be utilized to map and interpret Precambrian shield terranes characterized by sparse outcrop and abundant glacial cover. In addition to teaching basic outcrop mapping technique , students are introduced to geophysical surveying (gravity, magnetics), glacial drift prospecting, and drill core logging techniques in several of our geological mapping exercises. These mapping methodologies are particularly applicable to minerals exploration in shield terranes. The second and equally important goal of the PRC field camp is to teach students modern map-making and map production skills. During the fifth and sixth weeks of field camp, students conduct "capstone" mapping projects. These projects encompass one week of detailed bedrock mapping in remote regions of northern Minnesota that have not been mapped in detail (e.g. scales greater than 1:24,000) and a second week of map-making and map generation utilizing geographic information systems (currently ArcGIS10), graphics software packages (Adobe Illustrator CS4), and various imaging software for geophysical and topographic data. Over the past five years, PRC students and faculty have collaboratively published 21 geologic maps through the Precambrian Research Center Map Series. These maps are currently being utilized in a variety of ways by industry, academia, and government for mineral exploration programs, development of undergraduate, graduate, and faculty research projects, and for planning, archeological studies, and public education programs in Minnesota's state parks. Acquisition of specialized Precambrian geological mapping skills and geologic map-making proficiencies has

  13. Aeromagnetic signatures of Precambrian shield and suture zones of Peninsular India

    Directory of Open Access Journals (Sweden)

    Mita Rajaram

    2014-01-01

    Full Text Available In many Precambrian provinces the understanding of the tectonic history is constrained by limited exposure and aeromagnetic data provide information below the surface cover of sediments, water, etc. and help build a tectonic model of the region. The advantage of using the aeromagnetic data is that the data set has uniform coverage and is independent of the accessibility of the region. In the present study, available reconnaissance scale aeromagnetic data over Peninsular India are analyzed to understand the magnetic signatures of the Precambrian shield and suture zones thereby throwing light on the tectonics of the region. Utilizing a combination of differential reduction to pole map, analytic signal, vertical and tilt derivative and upward continuation maps we are able to identify magnetic source distribution, tectonic elements, terrane boundaries, suture zones and metamorphic history of the region. The magnetic sources in the region are mainly related to charnockites, iron ore and alkaline intrusives. Our analysis suggests that the Chitradurga boundary shear and Sileru shear are terrane boundaries while we interpret the signatures of Palghat Cauvery and Achankovil shears to represent suture zones. Processes like metamorphism leave their signatures on the magnetic data: prograde granulites (charnockites and retrograde eclogites are known to have high susceptibility. We find that charnockites intruded by alkali plutons have higher magnetization compared to the retrogressed charnockites. We interpret that the Dharwar craton to the north of isograd representing greenschist to amphibolite facies transition, has been subjected to metamorphism under low geothermal conditions. Some recent studies suggest a plate tectonic model of subduction–collision–accretion tectonics around the Palghat Cauvery shear zone (PCSZ. Our analysis is able to identify several west to east trending high amplitude magnetic anomalies with deep sources in the region from

  14. An REU Project on the Precambrian Rocks of Yellowstone National Park: Some lessons learned

    Science.gov (United States)

    Henry, D.; Mogk, D. W.; Mueller, P. A.; Foster, D. A.

    2014-12-01

    An NSF-funded REU project (2011-2013), based in Yellowstone National Park (YNP), was designed to characterize the geology, geochemistry and geochronology of Precambrian rocks in northern YNP. Over two field seasons two cadres of 12 students (12 women and 12 men) were chosen from small-to-large state universities and private colleges. REU students participated in three major activities constituting a complete research experience: Field studies involved geologic mapping and sampling of Precambrian basement; formulation of testable research questions by smaller working groups; and mapping and sampling projects to address research questions; Analytical studies, sample preparation immediately followed field work with petrographic analysis at students' home institutions and a week-long visit to analytical laboratories to conduct follow-up studies by small research groups during the academic year (Univ. Florida - geochemistry and geochronology; Univ. Minnesota - EMPA analysis); Communicating results, each working group submitted an abstract and collectively presented 13 posters at the 2011 and 2012 GSA Rocky Mountain sectional meetings. We used directed discovery to engage students in a community of practice in the field and found that a long apprenticeship (2-3 weeks) is optimal for novice-master interactions in exploring natural setting. Initial group hikes were used to normalize methods and language of the discipline. Students developed a sense of ownership of the overall project and assumed personal responsibility for directed research projects. Training was provided to: guide students in selection and appropriate use of tools; develop sampling strategies; discuss communal ethics, values, and expectations; develop efficient work habits; stimulate independent thinking; and engage decision-making. It was important to scaffold the field experience to students' level of development to lead to mastery. Analytical activities were designed from rock to analysis so that each

  15. 40Ar/39Ar dating of exceptional concentration of metals by weathering of Precambrian rocks at the Precambrian–Cambrian boundary

    DEFF Research Database (Denmark)

    Parnell, John; Mark, Darren F.; Frei, Robert

    2014-01-01

    The sub-Cambrian surface, including diverse metalliferous deposits, shows evidence of intense weathering of Precambrian rocks to form supergene-enriched ores and metalliferous placers, followed by widespread peneplanation. Much of the metal would have been flushed to the Cambrian ocean during...... with mobilization on land of redox sensitive metals by oxidative terrestrial weathering. This unprecedented flushing of metals from the weathered Precambrian surface would have contributed to the chemistry of the earliest Cambrian ocean at a time of marked faunal evolution....

  16. Coexistence and mixing of magmas in the late precambrian Itaporanga batholith, State of Paraiba, Northeastern Brazil

    International Nuclear Information System (INIS)

    Mariano, G.; Sial, A.N.

    1990-01-01

    The Precambrian Cachoeirinha-Salgueiro Fold Belt (CSF) located in the western portion of the states of Pernambuco and Paraiba is intruded, in its northern portion, by several coarsely porphyritic potassic calc-alkalic batholiths. These batholiths were syntectonically emplaced in relation to the Brasiliano cycle (=Pan-African) and are commonly associated with potassium diorites suggesting coexistence and mixing between felsic and mafic magmas. In the Itaporanga batholith three petrographic domains were mapped. A hybrid zone characterized by intense mechanical mixing of granite to granodiorite and potassium diorite magmas is located towards the border of the batholith. A commingling zone where felsic porphyritic granite to granodiorite and potassium diorite rocks are individualized at outcrop scale is located towards the center of the batholith. Finally a felsic porphyritic facies occur in the hybrid zone. Similarity among chemical analyses of amphiboles from potassium dioritic enclaves of the Itaporanga batholith and from the potassium diorite stock east of it suggest a common source for both magmas. This hypothesis is corroborated by similar REE patterns for potassium dioritic enclaves of the Itaporanga batholith and for the potassium diorite stock. The batholith shows a well developed foliation which dips towards its core suggesting that the present level of exposure represents the root zone of a diapir, where intense interaction between felsic and mafic magmas took place. (author)

  17. Geochronology and geochemistry of mafic dykes from the precambrians of Keonjhar, Orissa

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, A K; Sarkar, Amitabha [Geological Survey of India, Calcutta (India). Geochronology and Isotope Geology Division

    1994-01-01

    Two generations of mafic dolerite dykes with distinct geochemical signatures are recorded in the Champua-Keonjhargarh area of Keonjhar district in the eastern Indian precambrian craton (EIPC) on the basis of geochemical and K-Ar isotopic studies. The younger group-II dykes (ca. 1250 Ma) are mostly Fe-tholeiities, whereas the older group-I dykes (2100 +/- 100 Ma) show a wider compositional spectrum from Mg-Fe tholeiites to komatiitic basalts. The group-I dolerites show higher MgO content, Mg value. CaO/(Na){sub 2}O + K{sub 2}O and lower Fe{sub 2}O{sub 3}(T) and TiO{sub 2} contents compared to those in the group-II dykes. Consistent with their comparatively evolved nature, the group-II dolerites have lower Cr, Ni, total REE, Rb/Sr ratio and incompatible element abundances than those in the group-I dolerite rocks. Both the generations of dolerites, however, reveal enrichment in compatible elements and in this respect are similar to proterozoic dykes elsewhere in the world. Both groups of dykes reveal Fe-enrichment trend typical of tholeiitic intrusions in the FMA diagram- a feature mimicked by plots in the (Y + Zr) - 100 x TiO{sub 2} - Cr diagram. The available isotopic age data pertaining to the newer dolerite suite of Singhbhum - Keonjhar region of the EIPC are reviewed. (author). 29 refs., 15 figs., 4 tabs.

  18. Geochemistry of aquatic and terrestrial sediments, Precambrian shield of southeastern Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Hornbrook, E H.W.; Kettles, I M; Shilts, W W

    1986-12-01

    Lake water and sediment samples from approximately 2200 lakes and glacial sediment (sub-solum) samples from about 1800 sites were collected throughout a 38,000 km/sup 2/ rectangular area extending from Georgian Bay east to the Ottawa and St. Lawrence Rivers, Ontario, Canada. Lake water alkalinity and pH patterns are similar to the distribution of carbonate components in glacial drift. Carbonate-rich drift derived from the Paleozoic limestone terrain on the northeast flank of the Precambrian Frontenac Arch has been dispersed in a south-westward direction across a variety of non-calcareous metasedimentary and igneous rocks of the Canadian Shield, providing a buffering capacity to lakes situated in granitic terrain. The distribution patterns of mobile trace and minor elements are influenced by geochemical processes associated with subaerial weathering, ground and surface water transport, and the geochemical environment within the lakes themselves. Although composition of the drift is generally reflected by lake geochemistry, these post depositional processes can cause significant variations between patterns derived from the two sample types. Anions and cations such as SO/sub 4//sup 2 -/, Cl/sup -/, Na/sup +/, and F/sup -/ exhibit concentration patterns thought to reflect both anthropogenic inputs and natural variations due to differences in the geology. All regional geochemical patterns may show evidence of local enhancement caused by high concentrations of chemically distinctive minerals in drift or nearby bedrock. 4 references.

  19. The Trans-Rocky Mountain Fault System - A Fundamental Precambrian Strike-Slip System

    Science.gov (United States)

    Sims, P.K.

    2009-01-01

    Recognition of a major Precambrian continental-scale, two-stage conjugate strike-slip fault system - here designated as the Trans-Rocky Mountain fault system - provides new insights into the architecture of the North American continent. The fault system consists chiefly of steep linear to curvilinear, en echelon, braided and branching ductile-brittle shears and faults, and local coeval en echelon folds of northwest strike, that cut indiscriminately across both Proterozoic and Archean cratonic elements. The fault system formed during late stages of two distinct tectonic episodes: Neoarchean and Paleoproterozoic orogenies at about 2.70 and 1.70 billion years (Ga). In the Archean Superior province, the fault system formed (about 2.70-2.65 Ga) during a late stage of the main deformation that involved oblique shortening (dextral transpression) across the region and progressed from crystal-plastic to ductile-brittle deformation. In Paleoproterozoic terranes, the fault system formed about 1.70 Ga, shortly following amalgamation of Paleoproterozoic and Archean terranes and the main Paleoproterozoic plastic-fabric-producing events in the protocontinent, chiefly during sinistral transpression. The postulated driving force for the fault system is subcontinental mantle deformation, the bottom-driven deformation of previous investigators. This model, based on seismic anisotropy, invokes mechanical coupling and subsequent shear between the lithosphere and the asthenosphere such that a major driving force for plate motion is deep-mantle flow.

  20. The mineralogy and genesis of uranium in rhyolitic ignimbrites of Precambrian age from Duobblon, Sweden

    International Nuclear Information System (INIS)

    Smellie, J.A.T.

    1982-01-01

    The Duobblon rhyolitic ignimbrites, of middle Precambrian age are 60 m thick. They consist of at least three flows with varying degrees of welding and have undergone devitrification, producing lithophysal and spherulitic textures. They are overlain by thick fluviatile red-bed-type conglomerates and sandstones, which in turn are capped by terrestrial acid volcanics. Uranium enrichments of up to 3000 ppm U occur within two or three peneconcordant tabular horizons which are mostly lithophysae-bearing. Fission-track investigations of the ignimbrites and overlying conglomerates and sandstones, which supplement earlier mineralogical studies, show that U occurs as fine pitchblende disseminations; as complex uranotitanates associated with Fe-Ti-Mn oxides; and as coatings associated with matrix sericite. Small amounts of U are present in such primary accessory minerals as sphene, apatite, and zircon. It is suggested that oxidizing U-bearing solutions, generated partly during devitrification of the ignimbrites and partly from the overlying volcano-sedimentary pile, produced the U enrichments with later sulphide deposition, along the more permeable lithophysal horizons in the ignimbrites. (author)

  1. Aerial gamma spectrometry and aerial magnetometry of the occidental tract from Paulista Precambrian

    International Nuclear Information System (INIS)

    Ferreira, F.J.F.

    1991-01-01

    This work includes processing and interpretation of airborne spectrometric and magnetometric data of a 20.000 km 2 area between the cities of Sao Paulo and Pirassununga (Sao Paulo State, Brazil). Spectrometric maps were produced and interpreted, showing isorad curves for K, U and Th channels, U/Th, K/U and K/Th ratios, and F = K.U/Th. Main results are the following ones: a comparison between spectrometric and geological data at scale 1:50.000 Itu, Sorocaba, Sao Francisco and Morungaba granitoids showed satisfactory individualization of the bodies, discrimination of different sectors and/or mapping units and relations between facies zonality patterns and distribution of radioactivity levels of K, U and Th channels; airborne spectrometric and magnetometric data compared with geological data generally suggests classification for granitoid rocks following main current proposals of international literature; on the basis of magnetometric features of outcropping Precambrian terrains and with the help of filtered maps, it was possible to induce the tectonic framework of the basement complex covered by sediments and lavas of Parana Basin, with the help of filtered maps. Another interesting aspect was the definition of the tectonic border of this basin inside the studied area, which not only controlled the localization of Itu belt granitoids, but also may have affected the sedimentation in the basin by reactivation processes; finally it was shown that used methods are important mapping tools, which may contribute for the knowledge of the granitoids and the tectonic framework and for the study of metallogenic potential. (author)

  2. Precambrian Terranes of African affinities in the southeastern part of Brazil and Uruguay

    International Nuclear Information System (INIS)

    Preciozzi, F.; Basei, M.; Siga Junior, H.; Sato, K.; Kaufuss, G.

    2006-01-01

    The interest in correlating terranes at opposite margins of the South Atlantic Ocean reflects a natural curiosity of both researchers who work in the eastern South-America and who study southwestern Africa. On a large scale scenario the geology of this region is characterized by a central portion composed of Neoproterozoic-Cambrian belts (Dom Feliciano, Kao ko, Damara, Gariep, Saldania) having on each side old gneissic-migmatitic terrains on both continents (Luis Alves, Rio de La Plata, Kalahari and Congo). In South America the Neoproterozoic Dom Feliciano Belt (DFB) predominates in the eastern part of the region and is internally organized according to three different crustal segments characterized, from southeast to northwest, by a Granite belt (deformed I-type medium to high calc-alkaline granites and alkaline granitoid rocks; a Schist belt (volcano-sedimentary rocks metamorphosed from green schist to amphibolite facies and intrusive granitoids), and a Fore land basin (anchimetamorphic sedimentary and volcanic rocks), the latter situated between the Schist belt and the Archean-Paleoproterozoic fore land. Despite discontinuously covered by younger sediments, the NS continuity of these three crustal segments is suggested by similar lithotypes, structural characteristics, ages and isotopic signature, as well as by the gravimetric data. The Major Gercino, Cordilheira, and Sierra Ballena shear zones are part of the major NE-SW lineaments that affect all southern Brazilian and Uruguayan Precambrian terrains. They separate the Dom Feliciano Schist Belt (supra crustal rocks of the Brusque-Porongos and Lavalleja groups), to the West, from the granitoids of the Granite belt, to the East. The shear zones are characterized by a regional NE trend and a resultant oblique direction of movement where ductile-brittle structures predominate

  3. Iron isotope fractionation during pyrite formation in a sulfidic Precambrian ocean analogue

    Science.gov (United States)

    Rolison, John M.; Stirling, Claudine H.; Middag, Rob; Gault-Ringold, Melanie; George, Ejin; Rijkenberg, Micha J. A.

    2018-04-01

    The chemical response of the Precambrian oceans to rising atmospheric O2 levels remains controversial. The iron isotope signature of sedimentary pyrite is widely used to trace the microbial and redox states of the ocean, yet the iron isotope fractionation accompanying pyrite formation in nature is difficult to constrain due to the complexity of the pyrite formation process, difficulties in translating the iron isotope systematics of experimental studies to natural settings, and insufficient iron isotope datasets for natural euxinic (i.e. anoxic and sulfidic) marine basins where pyrite formation occurs. Herein we demonstrate, that a large, permil-level shift in the isotope composition of dissolved iron occurs in the Black Sea euxinic water column during syngenetic pyrite formation. Specifically, iron removal to syngenetic pyrite gives rise to an iron isotope fractionation factor between Fe(II) and FeS2 of 2.75 permil (‰), the largest yet reported for reactions under natural conditions that do not involve iron redox chemistry. These iron isotope systematics offer the potential to generate permil-level shifts in the sedimentary pyrite iron isotope record due to partial drawdown of the oceanic iron inventory. The implication is that the iron stable isotope signatures of sedimentary pyrites may record fundamental regime shifts between pyrite formation under sulfur-limited conditions and pyrite formation under iron-limited conditions. To this end, the iron isotope signatures of sedimentary pyrite may best represent the extent of euxinia in the past global ocean, rather than its oxygenation state. On this basis, the reinterpreted sedimentary pyrite Fe isotope record suggests a fundamental shift towards more sulfidic oceanic conditions coincident with the 'Great Oxidation Event' around 2.3 billion years ago. Importantly, this does not require the chemical state of the ocean to shift from mainly de-oxygenated to predominantly oxygenated in parallel with the permanent rise

  4. Outline of Upper Precambrian and Lower Paleozoic evolution of the Iberian Peninsula according to U-Pb dating of zircons

    International Nuclear Information System (INIS)

    Lancelot, J.R.; Allegret, A.; Iglesias Ponce de Leon, M.

    1985-01-01

    In the northwestern part of the Iberian Peninsula, recent geological studies have defined the following stratigraphic sequence from bottom to top: basal orthogneiss of Miranda do Douro is overlain by a complex of schist and greywacke which have been assigned to the Cambrian or late Precambrian; these are followed by the Ollo de Sapo gneisses of volcanic-sedimentary origin which in turn are overlain by the fossiliferous layers of the lower Ordovician. The schist and greywacke complex and the lower part of the Ollo de Sapo Formation are transected by granitic dikes (Viana del Bollo orthogneiss). All these rocks were folded, faulted, metamorphosed, and intruded by granite plutons during Variscan times. The emplacement of the Miranda do Douro and Viana del Bollo orthogneisses have been respectively dated at 618+-9 Ma and 465+-10 Ma by the U-Pb method on zircons. These data yield lower and upper limits for the deposition of the Ollo de Sapo Formation and demonstrate the occurrence of a Precambrian basement (''Pan-African'' or ''Cadomian'' orogeny) in the Variscan belt in the northwestern part of the Iberian Peninsula. The emplacement of Viana del Bollo orthogneiss could be genetically related to the main phase of crustal thinning (470-520 Ma) characteristic of the Prevariscan evolution of western Europe. Typology and U-Pb data of the Ollo de Sapo zircons indicate the occurrence of inherited old Precambrian zircons and yield an age of 325+-3 Ma for the Variscan main thermal event in the area considered. Four possible evolutionary models for the U-Pb system of the Ollo de Sapo zircons are discussed. (orig.)

  5. Active Deformation of Malawi Rift's North Basin Hinge Zone Modulated by Reactivation of Preexisting Precambrian Shear Zone Fabric

    Science.gov (United States)

    Kolawole, F.; Atekwana, E. A.; Laó-Dávila, D. A.; Abdelsalam, M. G.; Chindandali, P. R.; Salima, J.; Kalindekafe, L.

    2018-03-01

    We integrated temporal aeromagnetic data and recent earthquake data to address the long-standing question on the role of preexisting Precambrian structures in modulating strain accommodation and subsequent ruptures leading to seismic events within the East African Rift System. We used aeromagnetic data to elucidate the relationship between the locations of the 2009 Mw 6.0 Karonga, Malawi, earthquake surface ruptures and buried basement faults along the hinge zone of the half-graben comprising the North Basin of the Malawi Rift. Through the application of derivative filters and depth-to-magnetic-source modeling, we identified and constrained the trend of the Precambrian metamorphic fabrics and correlated them to the three-dimensional structure of buried basement faults. Our results reveal an unprecedented detail of the basement fabric dominated by high-frequency WNW to NW trending magnetic lineaments associated with the Precambrian Mughese Shear Zone fabric. The high-frequency magnetic lineaments are superimposed by lower frequency NNW trending magnetic lineaments associated with possible Cenozoic faults. Surface ruptures associated with the 2009 Mw 6.0 Karonga earthquake swarm aligned with one of the NNW-trending magnetic lineaments defining a normal fault that is characterized by right-stepping segments along its northern half and coalesced segments on its southern half. Fault geometries, regional kinematics, and spatial distribution of seismicity suggest that seismogenic faults reactivated the basement fabric found along the half-graben hinge zone. We suggest that focusing of strain accommodation and seismicity along the half-graben hinge zone is facilitated and modulated by the presence of the basement fabric.

  6. Modeling the Precambrian Topography of Columbia County, Wisconsin Using Two-Dimensional Models of Gravity and Aeromagnetic Data

    Science.gov (United States)

    Rasmussen, J.; Skalbeck, J.; Stewart, E.

    2017-12-01

    The deep sandstone and dolomite aquifer of Wisconsin is the primary source of water in the central, southern, and western portions of the state, as well as a supplier for many high-capacity wells in the eastern portion. This prominent groundwater system is highly impacted by the underlying Precambrian basement, which includes the doubly plunging Baraboo Syncline in Columbia and Sauk Counties. This project is a continuation of previous work done in Dodge and Fond du Lac Counties by the University of Wisconsin-Parkside (UW-P) and the Wisconsin Geological & Natural History Survey (WGNHS). The goal of this project was to produce of an updated Precambrian topographic map of southern Wisconsin, by adding Gravity and Aeromagnetic data to the existing map which is based mainly on sparse outcrop and well data. Gravity and Aeromagnetic data from the United States Geological Survey (USGS) was processed using GM-SYS 3D modeling software in Geosoft Oasis Montaj. Grids of subsurface layers were created from the data and constrained by well and drilling records. The Columbia County basement structure is a complex network of Precambrian granites and rhyolites which is non-conformably overlain by quartzite, slate, and a layer of iron rich sedimentary material. Results from previously collected cores as well as drilling done in neighboring Dodge County, show that the iron rich layer was draped over much of the Baraboo area before being subject to the multitude of folding and faulting events that happened in the region during the late Precambrian. This layer provides telltale signatures that aided in construction of the model due to having an average density of 3.7 g/cm3 and a magnetic susceptibility of 8000 x 10-6 cgs, compared to the average density and susceptibility of the rest of the bedrock being 2.8 g/cm3 and 1500 x 10-6 cgs, respectively. The research done on the Columbia County basement is one part of a larger project aimed at improving groundwater management efforts of the

  7. Petrochemical Characteristics and Age of Rare Metal (Ta-Nb Mineralization in Precambrian Pegmatites, Komu, Nigeria

    Directory of Open Access Journals (Sweden)

    A. OLUGBENGA

    2010-06-01

    Full Text Available The Precambrian pegmatites of Komu area intrude semi discordantly older rock types, such as biotite gneiss, amphibolites and pelitic schists. The pegmatites occur as near flat lying bodies. This study aims at elucidating the geological setting, petrography, geochemical features and age of mineralization of these pegmatite bodies, with a view to classifying them and knowing their economic potential. The petrographic analysis shows that the pegmatite samples contain mainly quartz (35%, plagioclase (15%, microcline (10% and muscovite (12% with accessories like tourmaline, tantalum, niobium and illmeno-rutiles. Geochemical analysis of the muscovites extracted from pegmatites show that these rocks are enriched in silica (>60% and Al2O3 (>12% and depleted in Fe2O3, MgO and TiO2. Trace element analysis shows that the pegmatites contain rare metals with moderately high Ta, Nb, Sn, Rb, Li and Cs values and depleted in Ti, Ba and Zr. Elemental ratios indicate low ratios of K/Cs, Th/U and K/Rb. Variation plots of Ta/(Ta+Nb versus Mn/ (Mn+Fe show that the pegmatites plot in the complex (beryl subtype field. The Na/K versus Sn, Nb, Rb variation plots show that the pegmatites of Komu area are mineralized and compare favourably with those of other mineralized pegma-tite areas like Egbe and Ijero in southwestern Nigeria. The variation plots of Ta versus K/Cs, and Ta/W versus Cs, also confirm rare metal mineralization of Komu pegmatites, which plot over the mineralized line of Beus and Gordiyenko. The K/Rb versus Rb, Cs and Sn plots indicate low K/Rb ratios indicating moderate differentiation. The Rare Earth Elements (REE show high heavy REE values and lower light REE values with prominent positive Ce anomaly and negative Eu anomaly from normalized chondrite plots. K/Ar dating of the age of mineralization of muscovites extracted from the pegmatite yielded late Pan-African ages between 502.8±13Ma and 514.5±13.2Ma. This period represents the cooling ages of the

  8. Abiogenic and Microbial Controls on Volatile Fatty Acids in Precambrian Crustal Fracture Waters

    Science.gov (United States)

    McDermott, J. M.; Heuer, V.; Tille, S.; Moran, J.; Slater, G.; Sutcliffe, C. N.; Glein, C. R.; Hinrichs, K. U.; Sherwood Lollar, B.

    2015-12-01

    Saline fracture waters within the Precambrian Shield rocks of Canada and South Africa have been sequestered underground over geologic timescales up to 1.1-1.8 Ga [1, 2]. These fluids are rich in H2 derived from radiolysis and hydration of mafic and ultramafic rocks [1, 2, 3] and host a low-biomass, low-diversity microbial ecosystem at some sites [2]. The abiogenic or biogenic nature of geochemical processes has important implications for bioavailable carbon sources and the role played by abiotic organic synthesis in sustaining a chemosynthetic deep biosphere. Volatile fatty acids (VFAs) are simple carboxylic acids that may support microbial communities in such environments, such as those found in terrestrial [4] and deep-sea [5] hot springs. We present abundance and δ13C analysis for VFAs in a spectrum of Canadian Shield fluids characterized by varying dissolved H2, CH4, and C2+ n-alkane compositions. Isotope mass balance indicates that microbially mediated fermentation of carbon-rich graphitic sulfides may produce the elevated levels of acetate (39-273 μM) found in Birchtree and Thompson mine. In contrast, thermodynamic considerations and isotopic signatures of the notably higher acetate (1.2-1.9 mM), as well as formate and propionate abundances (371-816 μM and 20-38 μM, respectively) found at Kidd Creek mine suggest a role for abiogenic production via reduction of dissolved inorganic carbon with H2 for formate, and oxidation of C2+ n-alkanes for acetate and propionate, along with possible microbial cycling. VFAs comprise the bulk of dissolved and total organic carbon in the mines surveyed, and as such represent a potential key substrate for life. [1] Holland et al. (2013) Nature 497: 367-360. [2] Lin et al. (2006) Science 314: 479-482. [3] Sherwood Lollar et al. (2014) Nature 516: 379-382. [4] Windman et al. (2007) Astrobiology 7(6): 873-890. [5] Lang et al. (2010) Geochim. Cosmochim. Acta 92: 82-99.

  9. The significance of marine microfossils for paleoenvironmental reconstruction of the Solimões Formation (Miocene), western Amazonia, Brazil

    Science.gov (United States)

    Linhares, Ana Paula; Gaia, Valber do Carmo de Souza; Ramos, Maria Inês Feijó

    2017-11-01

    Micropalaeontological studies of borehole cores 1AS-7D-AM and 1AS-8-AM, from Atalaia do Norte, Amazonas state, Brazil, support previous evidence for Miocene marine ingressions in Western Amazonia. Three marine incursion events are recorded: the first in the Early/early Middle Miocene (in both cores), the second in the late Middle/early Late Miocene (1AS-8-AM), and the third in the Late Miocene (1AS-7D-AM). The first event is characterized by exclusively mangrove taxa, and the last two present a mixture of marine, fresh, and brackish water taxa. However, at the end of the third event an increase of fluvial influence is demonstrated by the predominance of freshwater taxa. These marine incursions reached the study area through narrow and geographically limited connections, controlled by the tectonic setting, at a time between the Early/early Middle Miocene and late Middle/Late Miocene. Thereafter, fluvial conditions were reestablished before Pliocene times.

  10. Stratigraphic and microfossil evidence for a 4500-year history of Cascadia subduction zone earthquakes and tsunamis at Yaquina River estuary, Oregon, USA

    Science.gov (United States)

    Graehl, Nicholas A; Kelsey, Harvey M.; Witter, Robert C.; Hemphill-Haley, Eileen; Engelhart, Simon E.

    2015-01-01

    The Sallys Bend swamp and marsh area on the central Oregon coast onshore of the Cascadia subduction zone contains a sequence of buried coastal wetland soils that extends back ∼4500 yr B.P. The upper 10 of the 12 soils are represented in multiple cores. Each soil is abruptly overlain by a sandy deposit and then, in most cases, by greater than 10 cm of mud. For eight of the 10 buried soils, times of soil burial are constrained through radiocarbon ages on fine, delicate detritus from the top of the buried soil; for two of the buried soils, diatom and foraminifera data constrain paleoenvironment at the time of soil burial.We infer that each buried soil represents a Cascadia subduction zone earthquake because the soils are laterally extensive and abruptly overlain by sandy deposits and mud. Preservation of coseismically buried soils occurred from 4500 yr ago until ∼500–600 yr ago, after which preservation was compromised by cessation of gradual relative sea-level rise, which in turn precluded drowning of marsh soils during instances of coseismic subsidence. Based on grain-size and microfossil data, sandy deposits overlying buried soils accumulated immediately after a subduction zone earthquake, during tsunami incursion into Sallys Bend. The possibility that the sandy deposits were sourced directly from landslides triggered upstream in the Yaquina River basin by seismic shaking was discounted based on sedimentologic, microfossil, and depositional site characteristics of the sandy deposits, which were inconsistent with a fluvial origin. Biostratigraphic analyses of sediment above two buried soils—in the case of two earthquakes, one occurring shortly after 1541–1708 cal. yr B.P. and the other occurring shortly after 3227–3444 cal. yr B.P.—provide estimates that coseismic subsidence was a minimum of 0.4 m. The average recurrence interval of subduction zone earthquakes is 420–580 yr, based on an ∼3750–4050-yr-long record and seven to nine interearthquake

  11. A review of theories on the origins of saline waters and brines in the Canadian Precambrian Shield

    International Nuclear Information System (INIS)

    Bottomley, D.J.

    1996-02-01

    Groundwater at depths greater that 500 m in the Canadian Precambrian Shield is typically saline with a sodium-calcium/chloride chemical composition. Brines with dissolved solid concentrations exceeding 100 g/L have been encountered in several deep mines (>1000 m) on the Shield. Theories on the origins of these deep saline waters and brines can be grouped into two general categories: (1) autochthonous (in situ) origins attributable to silicate mineral hydrolysis over geologic time scales, leaching of fluid inclusions or radiolysis effects, and (2) allochthonous (external) sources caused by the infiltration of brine of modified seawater origins in the geologic past. Although the chemical and isotopic compositions of these waters clearly reflect the effects of reaction between the water and their silicate host rocks, it is unlikely that the high chlorinity of the brines is in an autochthonous attribute. It is proposed that the compositions of these brines are most compatible with the Paleozoic residual brine hypothesis of Spencer (1987). This theory invokes deep infiltration of a high-density residual brine, formed by the evaporation of seawater during Devonian time, into underlying Precambrian basement rocks where subsequent chemical modifications occurred. (author) 39 refs., 2 figs

  12. Diet Reconstructed From an Analysis of Plant Microfossils in Human Dental Calculus From the Bronze Age Site of Shilinggang, Southwestern China

    Science.gov (United States)

    Zhang, N.; Dong, G.; Yang, X.; Zuo, X.; Kang, L.; Ren, L.; Liu, H.; Li, H.; Min, R.; Liu, X.; Zhang, D.; Chen, F.

    2017-12-01

    The extracted microfossils from the dental calculus of ancient teeth are a new form of archaeological evidence which can provide direct information on the plant diet of a population. Here, we present the results of analyses of starch grains and phytoliths trapped in the dental calculus of humans who occupied the Bronze Age site of Shilinggang ( 2500 cal yr BP) in Yunnan Province, southwestern China. The results demonstrate that the inhabitants consumed a wide range of plants, including rice, millet, and palms, together with other food plants which have not previously been detected in Yunnan. The discovery of various underground storage organs (USOs; tubers, roots, bulbs, and rhizomes) and acorns complements the application of conventional macrofossil and isotope studies to understand the diet of the Bronze Age human population of Yunnan. The wide variety of plant foods consumed suggests that the inhabitants adopted a broad-spectrum strategy of gathering food and cultivating crops in northwest Yunnan Province in the late Bronze Age at a time when agricultural societies were developed in the central plains of China.

  13. 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

  14. Petrophysics Features of the Hydrocarbon Reservoirs in the Precambrian Crystalline Basement

    Science.gov (United States)

    Plotnikova, Irina

    2014-05-01

    A prerequisite for determining the distribution patterns of reservoir zones on the section of crystalline basement (CB) is the solution of a number of problems connected with the study of the nature and structure of empty spaces of reservoirs with crystalline basement (CB) and the impact of petrological, and tectonic factors and the intensity of the secondary transformation of rocks. We decided to choose the Novoelhovskaya well # 20009 as an object of our research because of the following factors. Firstly, the depth of the drilling of the Precambrian crystalline rocks was 4077 m ( advance heading - 5881 m) and it is a maximum for the Volga-Urals region. Secondly, petrographic cut of the well is made on core and waste water, and the latter was sampled regularly and studied macroscopically. Thirdly, a wide range of geophysical studies were performed for this well, which allowed to identify promising areas of collector with high probability. Fourth, along with geological and technical studies that were carried out continuously (including washing and bore hole redressing periods), the studies of the gaseous component of deep samples of clay wash were also carried out, which indirectly helped us estimate reservoir properties and fluid saturation permeable zones. As a result of comprehensive analysis of the stone material and the results of the geophysical studies we could confidently distinguish 5 with strata different composition and structure in the cut of the well. The dominating role in each of them is performed by rocks belonging to one of the structural-material complexes of Archean, and local variations in composition and properties are caused by later processes of granitization on different stages and high temperature diaphthoresis imposed on them. Total capacity of reservoir zones identified according to geophysical studies reached 1034.2 m, which corresponds to 25.8% of the total capacity of 5 rock masses. However, the distribution of reservoirs within the cut

  15. Lithospheric Expressions of the Precambrian Shield, Mesozoic Rifting, and Cenozoic Subduction and Mountain Building in Venezuela

    Science.gov (United States)

    Levander, A.; Masy, J.; Niu, F.

    2013-05-01

    reflecting the signatures of the Precambrian craton in the south, Mesozoic rifting in central Venezuela, and Neogene subduction and orogenesis in both the northeast and northwest. Specifically, LAB depth varies from 110-130 km beneath the Guayana Shield, in agreement with finite-frequency body wave tomography (Bezada et al., 2010b). To the north beneath the Serrania del Interior and Maturin Basin the Rayleigh waves image two high velocity features to depths of 200 km. The northernmost, beneath the Serrania, corresponds to the top of the subducting Atlantic plate, in agreement with P-wave tomography that images the Atlantic plate to transition zone depths. Another localized high velocity feature extending to ~200 km depth lies to the south. We speculate that this is a lithospheric drip caused by destabilization of the SA lithospheric caused by Atlantic subduction. Immediately to the west beneath the Cariaco basin the LAB is at ~50 km, marking the top of a pronounced low velocity zone. The thin lithosphere extends southwestward from the Cariaco Basin beneath the Mesozoic Espino Graben to the craton. To the west the LAB deepens to ~80 km beneath the Barinas Apure Basin and then to ~90 km beneath the Neogene Merida Andes and Maracaibo block.

  16. Precambrian terranes of African affinities in the southeastern part of Brazil and Uruguay

    International Nuclear Information System (INIS)

    Basei, M.A.S; Junior, Siga; Harara, O.M; Preciozzi, F; Sato, K; Kaufuss, G

    2001-01-01

    The interest in correlating terranes at opposite margins of the South Atlantic Ocean reflects a natural curiosity of both researchers who work in the eastern South-America and who study southwestern Africa. On a large scale scenario the geology of this region is characterized by a central portion composed of Neo proterozoic-Cambrian belts (Dom Feliciano, Kaoko, Damara, Gariep, Saldania) having on each side old gneissic-migmatitic terrains on both continents (Luis Alves, Rio de La Plata, Kalahari and Congo). In South America the Neoproterozoic Dom Feliciano Belt (DFB) predominates in the eastern part of the region and is internally organized according to three different crustal segments characterized, from southeast to northwest, by a Granite belt (deformed I-type medium to high calc-alkaline granites and alkaline granitoid rocks; a Schist belt (volcano-sedimentary rocks metamorphosed from greenschist to amphibolite facies and intrusive granitoids), and a Foreland basin (anchimetamorphic sedimentary and volcanic rocks), the latter situated between the Schist belt and the Archean-Paleoproterozoic foreland. Despite discontinuously covered by younger sediments, the NS continuity of these three crustal segments is suggested by similar lithotypes, structural characteristics, ages and isotopic signature, as well as by the gravimetric data. The Major Gercino, Cordilheira, and Sierra Ballena shear zones are part of the major NE-SW lineaments that affect all southern Brazilian and Uruguayan Precambrian terrains. They separate the Dom Feliciano Schist Belt (supracrustal rocks of the Brusque-Porongos and Lavalleja groups), to the West, from the granitoids of the Granite belt, to the East. The shear zones are characterized by a regional NE trend and a resultant oblique direction of movement where ductile-brittle structures predominate. It is here postulated, as discussed later on, that this lineament separates terranes that are geologically, geo chronologically and isotopically

  17. Precambrian-Cambrian provenance of Matinde Formation, Karoo Supergroup, northwestern Mozambique, constrained from detrital zircon U-Pb age and Lu-Hf isotope data

    Science.gov (United States)

    Bicca, Marcos Müller; Jelinek, Andrea Ritter; Philipp, Ruy Paulo; de Carvalho Lana, Cristiano; Alkmim, Ana Ramalho

    2018-02-01

    The Permian-Triassic time interval was a period of high sedimentation rates in the intracontinental Karoo rift basin of northwestern Mozambique, reflecting high exhumation rates in the surrounding high ground Precambrian-Cambrian basement and juxtaposed nappes. U-Pb LA-MC-ICPMS dating and Lu-Hf isotopic analysis of detrital zircons from the Late Permian-Early Triassic Matinde Formation of the Karoo Supergroup is used as a reliable proxy to map denudation patterns of source regions. Data allow discrimination of U-Pb age populations of ca. 1250-900 Ma, a secondary population between ca. 900-700 and a major contribution of ages around ca. 700-490 Ma. Zircon grains of the Mesoproterozoic age population present Mesoproterozoic (1000-1500 Ma) to Paleoproterozoic (1800-2300 Ma) Hf TDM ages, with positive (0 to +11) and negative εHf values (-3 to -15), respectively. The younger U-Pb age population also presents two different groups of zircon grains according to Lu-Hf isotopes. The first group comprise Paleoproterozoic (1800-2300 Ma) ages, with highly negative εHf values, between -10 and -22, and the second group exhibits Mesoproterozoic ages (1200-1500 Ma), with increased juvenile εHf values (ca. 0 to -5). These Hf isotopes reinforce the presence of unexposed ancient crust in this region. The oldest U-Pb age population resembles the late stages of Grenville Orogeny and the Rodinia Supercontinent geotectonic activity mostly represented by magmatic rocks, which are widely present in the basement of northern Mozambique. The juvenile Hf-isotope signature with an older age component is associated to rocks generated from subduction processes with crust assimilation by continental arcs, which we correlate to rocks of the Nampula Complex, south and east of the Moatize-Minjova Basin. The U-Pb ages between 900 and 700 Ma were correlated to the calc-alkaline magmatism registered in the Guro Suite, related to the breakup phase of Rodinia, and mark the western limit of the Moatize

  18. Metallogenesis of Precambrian gold deposits in the Wutai greenstone belt: Constrains on the tectonic evolution of the North China Craton

    Directory of Open Access Journals (Sweden)

    Ju-Quan Zhang

    2018-03-01

    Full Text Available The Wutai greenstone belt in central North China Craton (NCC hosts a number of Precambrian gold deposits and ore occurrences. Based on the host rock association, these can be divided into Banded Iron Formation (BIF, meta-volcano-sedimentary and meta-conglomerate types. The two former types formed during ∼2.5–2.3 Ga and the third one at ∼1.85 Ga. The characteristics of these Precambrian gold deposits are broadly similar with those of the orogenic gold deposits. Based on available geochronological data, here we reconstruct the major tectonic events and their relationship with gold mineralization in the Wutai-Hengshan-Fuping region during Neoarchean to Paleoproterozoic as follows. (1 ∼2.6–2.5 Ga: widespread intrusion of tonalite-trondhjemite-granodiorite (TTG magmas in the Hengshan terrane and Fuping continental arc, formation of the Wutai volcanic arc in the southern margin of Hengshan terrane with granitoids emplacement, and the Hengshan-Wutai intra-oceanic arc accretion to the Fuping arc at the end of Neoarchean. (2 ∼2.5–2.3 Ga: the subduction of Hengshan arc from north leading to persistent magmatism and orogenic gold mineralization. (3 ∼2.2–2.1 Ga: extension leading to the formation of graben structure in the Wutai and Fuping region, deposition of the Hutuo and Wanzi Group sediments, formation of placer gold through erosion of the orogenic gold deposits. (4 ∼2.2–2.0 Ga: widespread magmatism in the Wutai-Hengshan-Fuping region. (5 ∼1.95–1.8 Ga: regional metamorphism associated with collision of the Western and Eastern Blocks of the NCC and associated orogenic gold deposits. The multiple subduction-accretion-collision history and subsequent deep erosion has significantly affected most of the Precambrian gold deposits in the Wutai greenstone belt.

  19. Precambrian fluvial deposits: Enigmatic palaeohydrological data from the c. 2 1.9 Ga Waterberg Group, South Africa

    Science.gov (United States)

    Eriksson, Patrick G.; Bumby, Adam J.; Brümer, Jacobus J.; van der Neut, Markus

    2006-08-01

    Precambrian fluvial systems, lacking the influence of rooted vegetation, probably were characterised by flashy surface runoff, low bank stability, broad channels with abundant bedload, and faster rates of channel migration; consequently, a braided fluvial style is generally accepted. Pre-vegetational braided river systems, active under highly variable palaeoclimatic conditions, may have been more widespread than are modern, ephemeral dry-land braided systems. Aeolian deflation of fine fluvial detritus does not appear to have been prevalent. With the onset of large cratons by the Neoarchaean-Palaeoproterozoic, very large, perennial braided river systems became typical. The c. 2.06-1.88 Ga Waterberg Group, preserved within a Main and a smaller Middelburg basin on the Kaapvaal craton, was deposited largely by alluvial/braided-fluvial and subordinate palaeo-desert environments, within fault-bounded, possibly pull-apart type depositories. Palaeohydrological data obtained from earlier work in the Middelburg basin (Wilgerivier Formation) are compared to such data derived from the correlated Blouberg Formation, situated along the NE margin of the Main basin. Within the preserved Blouberg depository, palaeohydrological parameters estimated from clast size and cross-bed set thickness data, exhibit rational changes in their values, either in a down-palaeocurrent direction, or from inferred basin margin to palaeo-basin centre. In both the Wilgerivier and Blouberg Formations, calculated palaeoslope values (derived from two separate formulae) plot within the gap separating typical alluvial fan gradients from those which characterise rivers (cf. [Blair, T.C., McPherson, J.G., 1994. Alluvial fans and their natural distinction from rivers based on morphology, hydraulic processes, sedimentary processes, and facies assemblages. J. Sediment. Res. A64, 450-489.]). Although it may be argued that such data support possibly unique fluvial styles within the Precambrian, perhaps related to

  20. Fossil content and structural relationships of the San Luis zone and the Caborca zone of NW Sonora, Mexico, suppression of the precambrian Z of Caborca

    International Nuclear Information System (INIS)

    Radelli, Luigi; Solis Weiss, Vivianne; Dorame Navarro, Miguel; De La Cruz Ortega, Lissette del Carmen; Urrutia, Jose

    2008-01-01

    In the Caborca region of western Sonora a Precambrian Z does not cover a unique Precambrian socle as previously believed. Two tectonic zones occur there instead: the San Luis Zone and the Caborca Zone. The first is comprised of the Precambrian San Luis socle of gneiss and granite, crossed by 1.1 Ga old anorthosites, the San Luis sedimentary cover, and, above it, a Lower Jurassic volcano-sedimentary sequence. The Caborca Zone consists of the Precambrian Bamori socle of parametamorphic rocks crossed by 1.1 Ga old Aibo granite, and of the Gamuza sedimentary cover. 1.1 Ga ago the two zones were far away from each other. They have been brought together by the Nevadian orogeny. Both zones are allochthonous, and the Caborca Zone is a nappe upon the San Luis Zone. The lowermost units of the Gamuza cover furnished psammocorals and a possible Pterophyllum jageri (?). Accordingly, its geological age is either Palaeozoic or Triassic.The San Luis cover furnished Nematophites [Prototaxites (?) and Nematothallus] from its lower part; Calcispongiae, Cardaicarpus' seeds, and Artisia from its upper part Thus, it is a Devono-Carboniferous unit. The study area belongs in the Baja-Borderland block, which underwent, an Eocene northwards drifting of about 900 - 1000 km, and a 30 celsius degrade to 40 celsius degrade clockwise rotation relative to the main part of Sonora.

  1. Early-middle Eocene birds from the Lillebaelt Clay Formation of Denmark

    DEFF Research Database (Denmark)

    Lindow, Bent Erik Kramer

    2009-01-01

    The marine Lillebaelt Clay Formation of central Denmark is of early-middle Eocene age (late Ypresian - middle Lutetian; microfossil zones NP 13-NP 15). Over 20 bird fossils collected by amateur palaeontologists have been acquired through the Danish national ‘Danekrae' fossil treasure trove...... Clay Formation deposits derive from just after the Early Eocene Climate Optimum, a period of global elevated temperatures resulting from rapid greenhouse warming. Comparison between this bird assemblage and the recently revised assemblage from the older (earliest Ypresian) Fur Formation of Denmark...

  2. Uranium potential of precambrian rocks in the Raft River area of northwestern Utah and south-central Idaho. Final report

    International Nuclear Information System (INIS)

    Black, B.A.

    1980-09-01

    A total of 1214 geochemical samples were collected and analyzed. The sampling media included 334 waters, 616 stream sediments, and 264 rocks. In addition, some stratigraphic sections of Elba and Yost Quartzites and Archean metasedimentary rock were measured and sampled and numerous radiation determinations made of the various target units. Statistical evaluation of the geochemical data permitted recognition of 156 uranium anomalies, 52 in water, 79 in stream sediment, and 25 in rock. Geographically, 68 are located in the Grouse Creek Mountains, 43 in the Raft River Mountains, and 41 in the Albion Range. Interpretation of the various data leads to the conclusion that uranium anomalies relate to sparingly and moderately soluble uraniferous heavy minerals, which occur as sparse but widely distributed magmatic, detrital, and/or metamorphically segregated components in the target lithostratigraphic units. The uraniferous minerals known to occur and believed to account for the geochemical anomalies include allanite, monazite, zircon, and apatite. In some instances samarskite may be important. These heavy minerals contain uranium and geochemically related elements, such as Th, Ce, Y, and Zr, in sufficient quantities to account for both the conspicuous lithologic preference and the generally observed low amplitude of the anomalies. The various data generated in connection with this study, as well as those available in the published literature, collectively support the conclusion that the various Precambrian W and X lithostratigraphic units pre-selected for evaluation probably lack potential to host important Precambrian quartz-pebble conglomerate uranium deposits. Moreover it is also doubted that they possess any potential to host Proterozoic unconformity-type uranium deposits

  3. The Rae craton of Laurentia/Nuna: a tectonically unique entity providing critical insights into the concept of Precambrian supercontinental cyclicity

    Science.gov (United States)

    Bethune, K. M.

    2015-12-01

    Forming the nucleus of Laurentia/Nuna, the Rae craton contains rocks and structures ranging from Paleo/Mesoarchean to Mesoproterozoic in age and has long been known for a high degree of tectonic complexity. Recent work strongly supports the notion that the Rae developed independently from the Hearne; however, while the Hearne appears to have been affiliated with the Superior craton and related blocks of 'Superia', the genealogy of Rae is far less clear. A diagnostic feature of the Rae, setting it apart from both Hearne and Slave, is the high degree of late Neoarchean to early Paleoproterozoic reworking. Indeed, following a widespread 2.62-2.58 Ga granite bloom, the margins of Rae were subjected to seemingly continuous tectonism, with 2.55-2.50 Ga MacQuoid orogenesis in the east superseded by 2.50 to 2.28 Ga Arrowsmith orogenesis in the west. A recent wide-ranging survey of Hf isotopic ratios in detrital and magmatic zircons across Rae has demonstrated significant juvenile, subduction-related crustal production in this period. Following break-up at ca. 2.1 Ga, the Rae later became a tectonic aggregation point as the western and eastern margins transitioned back to convergent plate boundaries (Thelon-Taltson and Snowbird orogens) marking onset of the 2.0-1.8 Ga assembly of Nuna. The distinctive features of Rae, including orogenic imprints of MacQuoid and Arrowsmith vintage have now been identified in about two dozen cratonic blocks world-wide, substantiating the idea that the Rae cratonic family spawned from an independent earliest Paleoproterozoic landmass before its incorportation in Nuna. While critical tests remain to be made, including more reliable ground-truthing of proposed global correlations, these relationships strongly support the notion of supercontinental cyclicity in the Precambrian, including the Archean. They also challenge the idea of a globally quiescent period in the early Paleoproterozoic (2.45-2.2 Ga) in which plate tectonics slowed or shut down.

  4. Arroyo del Soldado group: paleontology, dating and Vendian to Lower Cambrian, Uruguay

    International Nuclear Information System (INIS)

    Gaucher, C.; Sprechmann, P.

    1998-01-01

    The fossil content of the Vendian to Lower Cambrian Arroyo del Soldado Group of the Nico Perez Terrane of Uruguay is analysed.Organic walled microfossils represented by acritarchs, eukariotic algae (sensu lato) and iron bacteria are recognized. An updated list of these microfossils is presented, which were are now reported in the Yerbal and Barriga Negra formations.Events of weutrphic conditions were reconstructed. The occurrence of Cloudina riemkeae, the earliest known metazoanwith a mineralized skeleton is communicated for the first time in Uruguay. The organic walled microfossils as well as Cloudina riemkeae are indicative of a Vendian age, whereas the trace fossils of the uppermost unit(Cerro Victoria) suggest the Early Cambrian. This would imply that the Group contains the Precambrian-Cambrian boundary. The Arroyo del Soldado Group is correlated with the Jacadiga and Corunba Groups (Brasil) and the Nama Group (Namibia). (author)

  5. Paleo-hydrological changes in the Chew Bahir area during the past 50 ka inferred from isotope signatures in aquatic microfossils

    Science.gov (United States)

    Junginger, Annett

    2017-04-01

    A major challenge in paleo-anthropology is to understand the impact of climatic changes on human evolution. The Hominin Sites and Paleo-lakes Drilling Project (HSPDP) is currently meeting that challenge by providing records that cover the last 3.7 Ma of paleoenvironmental change all located in close proximity to key paleo-anthropological findings in East Africa. One of the cored climatic archives comes from the Chew Bahir basin in southern Ethiopia, where duplicate sediment cores provide valuable insights about East African environmental variability during the last 550 ka. The lake basins in the eastern branch of the East African Rift System today contain mainly shallow and alkaline lakes. However, paleo-shorelines in the form of wave cut notches, shell beds, and beach ridges are common morphological evidences for deep freshwater lakes that have filled the basins up to their overflow level during pronounced humid episodes, such as the African Humid Period (15-5 ka). Unfortunately, further back in time, many of those morphological features disappear due to erosion and the estimation of paleo-water depths depend merely on qualitative proxies from core analyses. We here present a method that shows high potential to translate qualitative proxy signals from sediment core analyses to quantitative climate signals in the Ethiopian Rift. The method aims at water level reconstruction in the Chew Bahir basin using strontium isotope ratios (87Sr/86Sr, SIR) in lacustrine microfossils. SIR reflect the lithology of the drained catchment. SIR have changed pronouncedly when higher elevated paleo-lakes Abaya, Chamo and Awassa were overflowing into paleo-lake Chew Bahir. This new method may help to quantify paleo-lake levels beyond the past 20 ka and may also detect migrational barriers or routes due to the occurrence of synchronous large, connected and deep paleo-lakes.

  6. A New Morphological Phylogeny of the Ophiuroidea (Echinodermata Accords with Molecular Evidence and Renders Microfossils Accessible for Cladistics.

    Directory of Open Access Journals (Sweden)

    Ben Thuy

    Full Text Available Ophiuroid systematics is currently in a state of upheaval, with recent molecular estimates fundamentally clashing with traditional, morphology-based classifications. Here, we attempt a long overdue recast of a morphological phylogeny estimate of the Ophiuroidea taking into account latest insights on microstructural features of the arm skeleton. Our final estimate is based on a total of 45 ingroup taxa, including 41 recent species covering the full range of extant ophiuroid higher taxon diversity and 4 fossil species known from exceptionally preserved material, and the Lower Carboniferous Aganaster gregarius as the outgroup. A total of 130 characters were scored directly on specimens. The tree resulting from the Bayesian inference analysis of the full data matrix is reasonably well resolved and well supported, and refutes all previous classifications, with most traditional families discredited as poly- or paraphyletic. In contrast, our tree agrees remarkably well with the latest molecular estimate, thus paving the way towards an integrated new classification of the Ophiuroidea. Among the characters which were qualitatively found to accord best with our tree topology, we selected a list of potential synapomorphies for future formal clade definitions. Furthermore, an analysis with 13 of the ingroup taxa reduced to the lateral arm plate characters produced a tree which was essentially similar to the full dataset tree. This suggests that dissociated lateral arm plates can be analysed in combination with fully known taxa and thus effectively unlocks the extensive record of fossil lateral arm plates for phylogenetic estimates. Finally, the age and position within our tree implies that the ophiuroid crown-group had started to diversify by the Early Triassic.

  7. Provenance and tectonic setting of siliciclastic rocks associated with the Neoproterozoic Dahongliutan BIF: Implications for the Precambrian crustal evolution of the Western Kunlun orogenic belt, NW China

    Science.gov (United States)

    Hu, Jun; Wang, He; Wang, Min

    2017-10-01

    The Late Neoproterozoic Dahongliutan BIF is associated with siliciclastic rocks in the Tianshuihai terrane of the Western Kunlun orogenic belt (WKO), NW China. The sedimentary rocks have various weathering indices (e.g., CIA = 57-87, PIA = 61-96 and Th/U = 4.85-12.45), indicative of varying degrees of weathering in the source area. The rocks have trace element ratios, such as Th/Sc = 0.60-1.21 and Co/Th = 0.29-1.67, and light rare earth element (LREE) enriched chondrite-normalized REE patterns, suggesting that they were mainly sourced from intermediate and felsic rocks. Available U-Pb ages of detrital zircon from these rocks reveal that the detrital sources may have been igneous and metamorphic rocks from the WKO and the Tarim Block. Our study suggests that the Dahongliutan BIF and hosting siliciclastic rocks may have deposited in a setting transitional from a passive to active continental margin, probably related to the Late Neoproterozoic-Early Cambrian seafloor spreading and subduction of the Proto-Tethys Ocean. U-Pb dating of 163 detrital zircons defines five major age populations at 2561-2329 Ma, 2076-1644 Ma, 1164-899 Ma, 869-722 Ma and 696-593 Ma. These age groups broadly correspond to the major stages of supercontinent assembly and breakup events widely accepted for Columbia, Rodinia and Gondwana. Some zircons have TDM2 model ages of 3.9-1.8 Ga and negative εHf(t) values, suggesting that the Archean to Paleoproterozoic (as old as Eoarchean) crustal materials were episodically reworked and incorporated into the late magmatic process in the WKO. Some Neoproterozoic zircons have TDM2 model ages of 1.47-1.07 Ga and 1.81-1.53 Ga and positive εHf(t) values, indicating juvenile crustal growth during the Mesoproterozoic. Our new results, combined with published data, imply that both the Tianshuihai terrane in the WKO and the Tarim Block share the same Precambrian tectonic evolution history.

  8. Drill-hole data, drill-site geology, and geochemical data from the study of Precambrian uraniferous conglomerates of the Medicine Bow Mountains and Sierra Madre of southeastern Wyoming

    International Nuclear Information System (INIS)

    Karlstrom, K.E.; Houston, R.S.; Schmidt, T.G.; Inlow, D.; Flurkey, A.J.; Kratochvil, A.L.; Coolidge, C.M.; Sever, C.K.; Quimby, W.F.

    1981-02-01

    This volume is presented as a companion to Volume 1: The Geology and Uranium Potential of Precambrian Conglomerates in the Medicine Bow Mountains and Sierra Madre of Southeastern Wyoming; and to Volume 3: Uranium Assessment for Precambrian Pebble Conglomerates in Southeastern Wyoming. Volume 1 summarized the geologic setting and geologic and geochemical characteristics of uranium-bearing conglomerates in Precambrian metasedimentary rocks of southeastern Wyoming. Volume 3 is a geostatistical resource estimate of U and Th in quartz-pebble conglomerates. This volume contains supporting geochemical data, lithologic logs from 48 drill holes in Precambrian rocks of the Medicine Bow Mountains and Sierra Madre, and drill site geologic maps and cross-sections from most of the holes

  9. Drill-hole data, drill-site geology, and geochemical data from the study of Precambrian uraniferous conglomerates of the Medicine Bow Mountains and Sierra Madre of southeastern Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Karlstrom, K.E.; Houston, R.S.; Schmidt, T.G.; Inlow, D.; Flurkey, A.J.; Kratochvil, A.L.; Coolidge, C.M.; Sever, C.K.; Quimby, W.F.

    1981-02-01

    This volume is presented as a companion to Volume 1: The Geology and Uranium Potential of Precambrian Conglomerates in the Medicine Bow Mountains and Sierra Madre of Southeastern Wyoming; and to Volume 3: Uranium Assessment for Precambrian Pebble Conglomerates in Southeastern Wyoming. Volume 1 summarized the geologic setting and geologic and geochemical characteristics of uranium-bearing conglomerates in Precambrian metasedimentary rocks of southeastern Wyoming. Volume 3 is a geostatistical resource estimate of U and Th in quartz-pebble conglomerates. This volume contains supporting geochemical data, lithologic logs from 48 drill holes in Precambrian rocks of the Medicine Bow Mountains and Sierra Madre, and drill site geologic maps and cross-sections from most of the holes.

  10. Revision of species of Minerisporites, Azolla and associated plant microfossils from deposits of the Upper Palaeocene and Palaeocene/Eocene transition in the Netherlands, Belgium and the USA.

    Science.gov (United States)

    Batten, D J.; Collinson, M E.

    2001-05-01

    Species of the megaspore genus Minerisporites Potonié, megaspore apparatuses of species of the water fern Azolla Lamarck, and some associated organic-walled microfossils recovered from deposits of the Upper Palaeocene and Palaeocene/Eocene transition in the southern part of the Netherlands and neighbouring Belgium are redescribed on the basis of an examination of specimens under scanning and transmission electron microscopes. Originally studied about 40 years ago by S.J. Dijkstra, the re-examination has enabled emended diagnoses to be produced for six taxa: Minerisporites glossoferus (Dijkstra) Tschudy, M. mirabilis (Miner) Potonié, M. mirabilissimus (Dijkstra) Potonié, Azolla schopfii Dijkstra, A. teschiana Florschütz, and A. velus (Dijkstra) Jain and Hall. In addition, a revised description is provided for massulae of Salvinia Séguier that were originally thought to be megaspores and, hence, named by Dijkstra as Triletes? exiguus. The gross morphology and construction of the exospore of the species of Minerisporites are similar, but nevertheless sufficiently distinct for them to be maintained as separate taxa. Monolete microspores are preserved in hollows in the reticulate surface of some of the specimens of M. mirabilissimus. This is consistent with the presumed isoetalean affinity of Minerisporites. An apparent stratigraphic morphocline from M. glossoferus to M. mirabilis, suggested previously, is confirmed following our reassessment of their characteristics. The species of Azolla are all multi-floated, but they differ from each other in several ways, in particular with respect to the ultrastructure of the megaspore wall. They are also distinct from all other species that have been considered in sufficient detail for satisfactory comparisons to be made. The massulae of A. teschiana are described for the first time. The floats in A. velus are attached to the proximal part of the megaspore only by suprafilosal hairs. There are no maniculae. It is argued that

  11. Precambrian-Cambrian boundary in the Tal formation of Garhwal Lesser Himalaya : Rb-Sr age evidence from black shales underlying phosphorites

    International Nuclear Information System (INIS)

    Sharma, K.K.; Rameshwar Rao, D.; Azmi, R.J.; Gopalan, K.; Pantulu, G.V.C.

    1991-01-01

    The recently reported faunal evidence for placing the Precambrian-Cambrian boundary within the main phosphorite unit of the Chert-Phosphorite Member of the Tal Formation, Garhwal Lesser Himalaya, is supported by the present report of 626 ± 13 myr for the whole-rock Rb-Sr isochron age of the black shales directly underlying the phosphorite band. (author). 15 refs., 2 figs., 1 tab

  12. Interpreting Precambrian δ15N: lessons from a new modern analogue, the volcanic crater lake Dziani Dzaha

    Science.gov (United States)

    Ader, M.; Cadeau, P.; Jezequel, D.; Chaduteau, C.; Fouilland, E.; Bernard, C.; Leboulanger, C.

    2017-12-01

    Precambrian nitrogen biogeochemistry models rely on δ15N signatures in sedimentary rocks, but some of the underlying assumptions still need to be more robustly established. Especially when measured δ15N values are above 3‰. Several processes have been proposed to explain these values: non-quantitative reduction of nitrate to N2O/N2 (denitrification), non-quantitative oxidation of ammonium to N2O/N2, or ammonia degassing to the atmosphere. The denitrification hypothesis implies oxygenation of part the water column, allowing nitrate to accumulate. The ammonium oxidation hypothesis implies a largely anoxic water column, where ammonium can accumulates, with limited oxygenation of surface waters. This hypothesis is currently lacking modern analogues to be supported. We propose here that the volcanic crater lake Dziani Dzaha (Mayotte, Indian Ocean) might be one of them, on the basis of several analogies including: permanently anoxic conditions at depth in spite of seasonal mixing; nitrate content below detection limit in the oxic surface waters; accumulation of ammonium at depth during the stratified season; primary productivity massively dominated by cyanobacteria. One aspect may restrict the analogy: the pH value of 9-9.5. In this lake, δ15N values of primary producers and ammonium range from 6 to 9‰ and are recorded with a positive offset in the sediments (9ammonium was partly oxidized to N2O/N2.

  13. Uranium favorability of precambrian rocks in the Badger Flats - Elkhorn Thrust Area, Park and Teller Counties, Colorado

    International Nuclear Information System (INIS)

    Gallagher, G.L.

    1976-10-01

    The area is approximately 1,800 square miles and extends from Cripple Creek northward to Fairplay and Bailey. The Precambrian rocks include the metamorphic sequences of the Idaho Springs Formation and the Boulder Creek Granodiorite, Silver Plume Granite, Pikes Peak Granite, and Redskin Granite. The known uranium deposits in the area include six vein deposits, three pegmatite occurrences, and one zone of probable secondary enrichment; they have not yielded any significant production. The vein deposits are probably the result of downward percolation of ground water. The zone of secondary uranium enrichment may have formed above a volcanic pipe, vein, or tuffaceous lake bed. Favorability in the area is considered good for both vein and large, disseminated, low-grade uranium deposits. On the bases of known uranium occurrences, favorable structures and host rocks, and a water-sampling program, recommendations are given for exploration. The occurrences in the area have substantial similarities with the Rossing deposit in South-West Africa and the Wheeler Basin uranium occurrence in Grand County, Colorado. 6 figures, 9 tables

  14. 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

  15. Environmental investigations using diatom microfossils

    Science.gov (United States)

    Smith, Kathryn E.L.; Flocks, James G.

    2010-01-01

    Diatoms are unicellular phytoplankton (microscopic plant-like organisms) with cell walls made of silica (called a frustule). They live in both freshwater and saltwater and can be found in just about every place on Earth that is wet. The shape and morphology of the diatom frustule unique to each species are used for identification. Due to the microscopic size of diatoms, high-power microscopy is required for diatom identification. Diatoms are vital to life on Earth. They are photosynthetic primary producers, using sunlight to create oxygen and organic carbon from carbon dioxide and water. They are a significant source of the oxygen we breathe, have a major impact on the global carbon cycle (Smetacek, 1999), and are a food source for many aquatic organisms (Mann, 1993). Diatom abundance has even been demonstrated to have an influence on the diversity of larger marine mammals, including whales (Marx and Uhen, 2010). Data on diatom abundance and diversity are extremely useful in environmental studies.

  16. Sm-Nd study of Precambrian crustal development in the Prieska-Copperton region, Cape Province

    International Nuclear Information System (INIS)

    Cornell, D.H.; Hawkesworth, C.J.; Van Calsteren, P.; Scott, W.D.

    1986-01-01

    Samples representing the major lithological units between Copperton and Prieskapoort in the Cape Province have been analysed for Sm and Nd concentrations and Nd isotopic compositions. The ∼ 3000 Ma Marydale Group is shown to extend without major chronostratigraphic breaks from slightly metamorphosed basalt and arkose west of the Doornberg Fault at Prieskapoort to highly metamorphosed gneisses east of the Brakbos Fault at Copperton. Evidence is found of plutonic alkaline igneous activity, and possibly volcanism, which occurred during the ∼ 1 900 Ma Kheis tectogenesis. Early Proterozoic material apparently dominates the lower crustal region of the eastern Namaqua Province sampled by kimberlites. Sm-Nd data for the Copperton Formation of the Namaqua Province places an upper limit of ∼ 1 514 Ma and lower limit of ∼ 1 350 Ma on its origin. Omission of basaltic samples from the isochron regression yields the younger age, which is more easily reconciled with Pb isotope data. Volcanism is envisaged from a mantle source with a history of light rare-earth depletion relative to the chondritic earth model. By analogy with modern tectonic environments, the Copperton Formation probably formed in an active continental margin or island arc environment

  17. Morphological and ecological complexity in early eukaryotic ecosystems.

    Science.gov (United States)

    Javaux, E J; Knoll, A H; Walter, M R

    2001-07-05

    Molecular phylogeny and biogeochemistry indicate that eukaryotes differentiated early in Earth history. Sequence comparisons of small-subunit ribosomal RNA genes suggest a deep evolutionary divergence of Eukarya and Archaea; C27-C29 steranes (derived from sterols synthesized by eukaryotes) and strong depletion of 13C (a biogeochemical signature of methanogenic Archaea) in 2,700 Myr old kerogens independently place a minimum age on this split. Steranes, large spheroidal microfossils, and rare macrofossils of possible eukaryotic origin occur in Palaeoproterozoic rocks. Until now, however, evidence for morphological and taxonomic diversification within the domain has generally been restricted to very late Mesoproterozoic and Neoproterozoic successions. Here we show that the cytoskeletal and ecological prerequisites for eukaryotic diversification were already established in eukaryotic microorganisms fossilized nearly 1,500 Myr ago in shales of the early Mesoproterozoic Roper Group in northern Australia.

  18. Contemporary Rigidity of Precambrian and Paleosoic Platform on the Area of Poland on the Base of GPS Data

    Science.gov (United States)

    Kontny, B.; Grzempowski, P.; Bogusz, J.; Jarosinski, M.; Klos, A.

    2012-12-01

    Now it became obvious in the world literature that Cenozoic intraplate deformations of the Northwestern Eurasia were connected with the Alpine plate collision. However, relations of the Cenozoic intraplate deformations with the contemporary spreading in the north and transcontinental shears along the Tornquist line and Urals must be taken into account as well. On the contrary, in East Europe, periods of the activity being coincident with those in the Caucasus and the phases of the Red Sea opening. It is also evidence that the southern East European craton belongs to the Periarabian collision area. A compression axis orientation was sub latitudinal there, this allows suggestion that the deformations were originated under pressure of the adjacent Urals. According to some authors the present view of unity and rigidity of the Cenozoic Eurasian plate is correct only at the first approximation. In reality, the Eurasian plate represented a time varying kaleidoscope of sub plates that moved at different velocities from the Atlantic-Arctic spreading axis. Contemporary image of the intraplate deformation can be verified on the basis of observations of permanent stations GPS at present. Density the IGS and EPN station on the North-East Eurasian area isn't sufficient to the credible estimation of geokinematics parameters of every sub plates (platforms). But national networks of the GBAS stations, as for example a Polish network ASG-EUPOS, are ensuring the much higher density of measuring stations (average distance between stations of the c 70 km). Stations are located on both sides of the Teisseyre - Tornquist zone, both on East-European Precambrian platform (East European Craton) as well as on West-European Paleozoic platform. Three-year period of permanent GPS observation on ASG-EUPOS stations enabled the estimation of the velocities of the stations with the sufficing accuracy for the geodynamic purposes. It gave the possibility of the evaluation of contemporary rigidity of

  19. The composition of the ground water in bedrock in the precambrian shield areas of Finland and other countries

    International Nuclear Information System (INIS)

    Hyyppae, J.

    1986-11-01

    The main properties of the composition of the ground water contained in the Precambrian bedrock of Finland are presented on the basis of the results of analyses of some 1750 water samples taken from bored wells and a few mines. They show that, with a few exceptions, the waters of bored wells are bicarbonate waters, in which the average total amount of dissolved substances diminishes according to their geographical location as one moves from the coastal areas toward estern and northern Finland. The influence of the mineral composition of the bedrock appears most distinctly in the rapakivi areas, where the average fluoride content of the ground water varies between 1.5 and 2.0 mg/l and is thus ten times the corresponding content prevailing in areas characterized by other types of rocks. Ground waters containing from 439 to 18.000 mg/l of chloride have also been met with in Finnish bedrock and the location of the sampling site of 38 samples is given together with the general nature of their chemical composition as well as the results of the determinations of the stable (δ ''2H, δ ''1''8O, δ ''3''4S, δ ''1''3C) and radioactive (''3H, ''1''4C) isotopes of a number of samples. The saline waters are mostly located in the region covered 6000-7500 years ago by the Littorina Sea. On the other hand, the isotopic composition of many saline waters corresponds to that of rainwater fallen during climatic conditions colder than the present. The most saline waters have been met with deep down in mines and deep boreholes, also, for example, far from the region covered by the Littorina Sea. The saline waters contained in Finnish bedrock usually release gas, which in some cases consists mainly of nitrogen but in some places includes significant amounts of methane. In addition, helium is one of the constituents

  20. New Au-U deposit type in the weathering crust in tectonicmetasomatite zones of Pre-Cambrian shields

    International Nuclear Information System (INIS)

    Tarkhanov, A.

    2014-01-01

    Au-U mineralization is widely distributed in the tectonic-metasomatite zones of Pre-Cambrian shields (Aldan Shield, Ukraine Shield and others). The industrial ores are located only in several areas at depths of more than 150-300 m. Uranium mineralization is represented by uranotitnates and the gold mineralization by auriferous pyrite. The zone of weathering is present to the depth of 100-150 m. The feldspars are replaced by the clay minerals, carbonates are dissovled, sulfides are oxidized and the secondary minerals of uranium replace uranotitanates.The golden mineralization in the envelope of weathering is represented by the fine-grained native gold. The particle size is 40-50 nm. Uranium mineralization is in the form of relict brannerite, tuyamunite, torbernite, carnotite. The gold content is 1-2 g/t, and uranium content 0.01- 0.05% U. Ore bodies of gold and uranium are located inside the tectonic-metasomatite zones. The zones of maximum concentration of these metals may not coincide. The gold ore bodies have the length of hundreds meters and a thickness of 1-5 m. The vertical extent of the secondary Au-U mineralization is 100-150 m. 20 laboratory samples of ore from the weathered zone were tested by the method of heap leaching. The first stage is the uranium leach by diluted sulfuric acid. The second stage is the cyanation of gold and silver. The experimental data indicates leach rate of uranium 75%, gold 80-97%, silver 50-60%. Gold resources in the continous zone is estimated to be 80 t. Gold resources of the several other zones inside the area of 100 km 2 are estimated as 220 t. The heap leach process can be used for profitable development of the low-grade deposits. This method helps to increase the resources of gold and uranium. (author)

  1. Episodic reactivation of a Late Precambrian mylonite zone on the Gondwanan Margin of the Appalachians, southern Newfoundland

    Science.gov (United States)

    O'Brien, B. H.; O'Brien, S. J.; Dunning, G. R.; Tucker, R. D.

    1993-08-01

    The Grand Bruit Fault Zone of southern Newfoundland is a fundamental structure within Late Precambrian basement on the Gondwanan margin of the Appalachian orogen. Within the fault zone, a sequence of structures documents changes in the sense of ductile displacement from (1) reverse dip slip, to (2) dextral strike slip, to (3) sinistral oblique slip, and, finally, to (4) dextral lateral offsets. Fault movements along this structure were punctuated by emplacement of a variety of plutons and minor intrusions which, when precisely dated, allow these movements to be bracketed at between 571 Ma and 564 Ma, 497 Ma and 427 Ma, 424 Ma and 420 Ma, and 421 Ma and 387 Ma, respectively. The tectonic evolution of the Gondwanan inlier of southern Newfoundland is mirrored, in large part, by the record of mylonite development within the Grand Bruit Fault Zone. These tectonic events are attributable to well-constrained, regional orogenic events of both the Pan-African and Appalachian cycles. Newly formed shear zones in the fault zone reactivate parts of much older faults of similar regional orientation and are, in some cases, kinematically indistinguishable from the ancestral structures. Integration of precise geochronological data with the sequence of overprinted fault structures demonstrates that, although the role of progressive deformation in shear zone development was important, the observed disposition of structures and rock units is primarily a function of polyorogenic accretion. As a multiple-reactivated structural lineament in a Gondwanan basement inlier, the fault zone exerted fundamental control over the tectonic development of the leading edge of the convergent southeast margin of the orogen.

  2. THE PRECAMBRIAN HISTORY OF THE ORIGIN AND EVOLUTION OF THE SOLAR SYSTEM AND EARTH. PART 1

    Directory of Open Access Journals (Sweden)

    M. I. Kuz’min

    2014-01-01

    Full Text Available The paper provides a review of early stages of development the Solar System and the geological history of Earth with reference to the latest data on the origin of the Solar System and the formation of the first continental rocks and results of studies of zircon, the oldest mineral so far dated on Earth. The formation of the Solar System from a gas-and-dust nebula is estimated to have begun 4.568 billion years ago. Ice was formed 1.5 million years later; it concentrated at the periphery of the system and served as the material for the largest planets, Jupiter and Saturn. In the central areas of the system, asteroids with diameters of about 10 km were formed. Their small bodies were composed of the basic material of the solar nebula, as evidenced by carbonaceous chondrite, CI, which composition is similar to the composition of the Sun, with the exception of hydrogen, helium, and volatile components that served as the main material for peripheral planets of the Solar System. Due to collision and partial merger of such small bodies, the formation of embryos of the terrestrial planets was initiated. Gravity made such embryos to cluster into larger bodies. After 7 million years, large asteroids and planet Mars were formed. It took 11 million years to form Planet Earth with a mass of 63 %, and 30 million years to form 93 % of its mass. Almost from the beginning of the formation of the Earth, short-lived radionuclides, 26Al and 60Fe, caused warming up of the small planetary bodies which led to the formation of their cores. During the initial stages, small magma reservoirs were formed, and molten iron particles gathered in the centres of the planetary bodies. As suggested by the ratio of 182W/184W, the major part of the core was formed within 20 million years, while its full mass accumulated completely within the next 50 million years. In 30–40 million years after the creation of the Solar System, the Earth collided with a cosmic body which mass was

  3. U-Pb zircon geochronology and Sm-Nd-Pb isotopic constraint for precambrian plutonic rocks in the northeastern part of Ryeongnam massif, Korea

    International Nuclear Information System (INIS)

    Chang, Ho-Wan

    2003-01-01

    The Ryeongnam massif is composed of Precambrian gneisses, Paleozoic and Mesozoic sedimentary rocks and extensive Triassic-Jurassic plutonic rocks of felsic to mafic composition. In the northeast Ryeongnam massif, the oldest rocks belong to the Sobaegsan gneiss complex, which is composed of orthogneisses, paragneisses and mafic plutonic rocks. U-Pb zircon ages for the felsic and mafic intrusive bodies within the Sobaegsan gneiss complex are: the Icheon granite gneiss, 2357±43 and 2342±47 Ma; the Buncheon granite gneiss, 1963±5 Ma; the Pyeonghae granite gneiss, 1936±21 Ma; the Ogbang amphibolite, 1918±10 Ma; the Imwon leucogranite gneiss, 1826±20 Ma. The Hyeondong biotite schist, which is intruded by the Buncheon granite gneiss and the Ogbang amphibolite, yielded an age of 2271±44 Ma. The Nd-Sm-Pb isotopic data indicate that the felsic plutonic rocks are derived from an older Archean crust. The Nd T DM ages are Archean, and the εNd values are negative for the felsic rocks and positive for the amphibolite. Common Pb isotope compositions also indicate a crustal source for the felsic intrusives. The U-Pb ages of Precambrian rocks of the Ryeongnam massifs are similar to those in the Gyeonggi massif, and may have a similar crustal evolutionary history. The Precambrian rocks of South Korea could be related either to the North China block or to the South China block, as the isotope ages and patterns are not unique to either block. Similarly, a geologic correlation with Japan, although possible, is tenuous at present. (author)

  4. Past and future fracturing in AECL Research areas in the superior province of the Canadian Precambrian Shield, with emphasis on the Lac du Bonnet Batholith

    Energy Technology Data Exchange (ETDEWEB)

    Brown, A; Everitt, R A; Martin, C D; Davison, C C [Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Labs.

    1995-10-01

    The likelihood that future fracturing, arising from geologic causes, could occur in the vicinity of a nuclear fuel waste repository in plutonic rock of the Canadian Precambrian Shield, is examined. The report discusses the possible causes of fracturing (both past and future) in Shield rocks. The report then examines case histories of fracture formation in Precambrian plutonic rocks in AECL`s Research Areas, especially the history of the Lac du Bonnet Batholith, in the Whiteshell Area, Manitoba. Initially, fractures can be introduced into intrusive plutonic rocks during crystallization and cooling of an intrusive magma. These fractures are found at all size scales; as late residual magma dyking, hydraulic fracturing by retrograde boiling off of hydrothermal fluids, and, in some cases, through local differential cooling. Subsequent fracturing is largely caused by changes in environmental temperature and stress field, rather than by alteration of the material behaviour of the rock. Pluton emplacement during orogeny is commonly accompanied by uplift and erosional exhumation, altering both the tectonic and the lithostatic stresses, the rock temperature gradient and the pore fluid characteristics.

  5. Potassium, uranium, thorium radiogenic heat contribution to heat flow in the Precambrian and younger silicic rocks of the Zuni and Florida Mountains, New Mexico (U.S.A.)

    International Nuclear Information System (INIS)

    Brookins, D.G.

    1982-01-01

    High heat flow in the Zuni Mountains, New Mexico, U.S.A., has been explained by the possible presence of a buried felsic pluton. Alternately, high K, U, Th abundances have been proposed to account for part of the high heat flow. The mean radiogenic heat contricution for 60 samples of Precambrian core rocks is 7.23 μcal/gm-yr, which is slightly higher than the average for western U.S.A. granitic rocks and significantly higher than the average for continental 'crust'; hence, the K, U, Th radiogenic contribution from Precambrian rocks to the overall heat flow is significant. Radiogenic K, U, Th heat for 32 samples for the Florida Mountains, New Mexico, U.S.A., yields a lower mean of 5.46 μcal/gm-yr. This value is somewhat anomalous in that the predominantly syenitic rocks commonly yield higher values. Furthermore, heat flow is higher in areas distant from the Floridas and the radiogenic heat contribution is considered small. (orig.)

  6. Past and future fracturing in AECL Research areas in the superior province of the Canadian Precambrian Shield, with emphasis on the Lac du Bonnet Batholith

    International Nuclear Information System (INIS)

    Brown, A.; Everitt, R.A.; Martin, C.D.; Davison, C.C.

    1995-10-01

    The likelihood that future fracturing, arising from geologic causes, could occur in the vicinity of a nuclear fuel waste repository in plutonic rock of the Canadian Precambrian Shield, is examined. The report discusses the possible causes of fracturing (both past and future) in Shield rocks. The report then examines case histories of fracture formation in Precambrian plutonic rocks in AECL's Research Areas, especially the history of the Lac du Bonnet Batholith, in the Whiteshell Area, Manitoba. Initially, fractures can be introduced into intrusive plutonic rocks during crystallization and cooling of an intrusive magma. These fractures are found at all size scales; as late residual magma dyking, hydraulic fracturing by retrograde boiling off of hydrothermal fluids, and, in some cases, through local differential cooling. Subsequent fracturing is largely caused by changes in environmental temperature and stress field, rather than by alteration of the material behaviour of the rock. Pluton emplacement during orogeny is commonly accompanied by uplift and erosional exhumation, altering both the tectonic and the lithostatic stresses, the rock temperature gradient and the pore fluid characteristics

  7. On the possibility of life on early Mars

    Science.gov (United States)

    Oberbeck, V. R.; Fogleman, G.

    1990-01-01

    Prebiotic reactants, liquid water, and temperatures low enough for organic compounds to be stable are requirements for the origination of life as we know it. Prebiotic reactants and sufficiently low temperatures were present on Mars before liquid water vanished. Early in this time period, however, large planetesimal impacts may have periodically sterilized Mars, pyrolyzed organic compounds, and interrupted chemical origination of life. However, the calculated time interval between such impacts on Mars was larger just before liquid water vanished 3.8 Gyr (billion years) ago than it was on earth just before life originated. Therefore, there should have been sufficient time for life to originate on Mars. Ideal sites to search for microfossils are in the heavily cratered terrain of Upper Noachian age. Craters and channels in this terrain may have been the sites of ancient lakes and streams that could have provided habitats for the first microorganisms.

  8. Geochemical interpretation of the Precambrian basement and overlying Cambrian sandstone on Bornholm, Denmark: Implications for the weathering history

    Science.gov (United States)

    Zhou, Lingli; Friis, Henrik; Yang, Tian; Nielsen, Arne Thorshøj

    2017-08-01

    A geochemical study of the Precambrian basement granites from the Borggård borehole on Bornholm, Denmark, suggests that the granites were moderately weathered (Chemical Index of Alteration-CIA = 66-71) during subaerial exposure in a humid climate. The microcline is well preserved, whereas plagioclase was thoroughly altered to clay minerals (Plagioclase Index of Alteration-PIA = 93-99) which is likely due to its original Ca-rich composition. The primary Fe-Ti accessory minerals were oxidized to hematite and anatase. Evidence from REE distribution patterns and immobile element ratios, e.g. Zr/Hf and Nb/Ta, between the weathered basement granite from the Borggård borehole and regional granitoids on Bornholm, constrains the Svaneke Granite as the original basement lithology. A tau (τ) mass transport model (assuming immobile Ti) was applied to quantify the mass transfer during weathering of the basement granite. The results show a depletion of major elements in the following order: Na > Ca > Mg > Si; Al and Ti are immobile and stay constant; K shows sample dependent enrichment or depletion; Fe is slightly enriched. The Cambrian sandstone overlying the basement in the Borggård borehole, assigned to the Gadeby Member of the Nexø Formation, is feldspathic litharenite-litharenite in composition. Provenance indicators including (Gd/Yb)N, Zr/Hf and Nb/Ta ratios and petrological features indicate that source material was derived from both weathered and fresh basement granite of intermediate composition. The Gadeby Member equivalents in Germany, the basal lower Cambrian Adlergrund Konglomerat Member (AKM) in the offshore G-14 well north of Rügen, and the approximately coeval Lubmin Sandstein Formation (LSF) from the Loissin-1 borehole, mainland Germany, must have been sourced from a basement with compositions comparable to the intermediate group of the regional granitoids on Bornholm. The source materials for the AKM (CIA = 71-72, PIA = 94-96), the Gadeby Member in the

  9. SECULAR CHANGES IN RELATIONSHIPS BETWEEN PLATE-TECTONIC AND MANTLE-PLUME ENGENDERED PROCESSES DURING PRECAMBRIAN TIME

    Directory of Open Access Journals (Sweden)

    M. V. Mints

    2016-01-01

    Full Text Available Paradoxically, the lists of “proxies” of both plate- and plume-related settings are devoid of even a mention of the high-grade metamorphic rocks (granulite, amphibolite and high-temperature eclogite facies. However, the granulite-gneiss belts and areas which contain these rocks, have a regional distribution in both the Precambrian and the Phanerozoic records. The origin and evolution of the granulite-gneiss belts correspond to the activity of plumes expressed in vigorous heating of the continental crust; intraplate magmatism; formation of rift depressions filled with sediments, juvenile lavas, and pyroclastic flow deposits; and metamorphism of lower and middle crustal complexes under conditions of granulite and high-temperature amphibolite facies that spreads over the fill of rift depressions also. Granulite-gneiss complexes of the East European Craton form one of the main components of the large oval intracontinental tectonic terranes of regional or continental rank. Inclusion of the granulite-gneiss complexes from Eastern Europe, North and South America, Africa, India, China and Australia in discussion of the problem indicated in the title to this paper, suggests consideration of a significant change in existing views on the relations between the plate- and plume-tectonic processes in geological history, as well as in supercontinent assembly and decay. The East European and North American cratons are fragments of the long-lived supercontinent Lauroscandia. After its appearance at ~2.8 Ga, the crust of this supercontinent evolved under the influence of the sequence of powerful mantle plumes (superplumes up to ~0.85 Ga. During this time Lauroscandia was subjected to rifting, partial breakup and the following reconstruction of the continent. The processes of plate-tectonic type (rifting with the transition to spreading and closing of the short-lived ocean with subduction within Lauroscandia were controlled by the superplumes. Revision of the

  10. Constraining a Precambrian Wilson Cycle lifespan: An example from the ca. 1.8 Ga Nagssugtoqidian Orogen, Southeastern Greenland

    Science.gov (United States)

    Nicoli, Gautier; Thomassot, Emilie; Schannor, Mathias; Vezinet, Adrien; Jovovic, Ivan

    2018-01-01

    In the Phanerozoic, plate tectonic processes involve the fragmentation of the continental mass, extension and spreading of oceanic domains, subduction of the oceanic lithosphere and lateral shortening that culminate with continental collision (i.e. Wilson cycle). Unlike modern orogenic settings and despite the collection of evidence in the geological record, we lack information to identify such a sequence of events in the Precambrian. This is why it is particularly difficult to track plate tectonics back to 2.0 Ga and beyond. In this study, we aim to show that a multidisciplinary approach on a selected set of samples from a given orogeny can be used to place constraints on crustal evolution within a P-T-t-d-X space. We combine field geology, petrological observations, thermodynamic modelling (Theriak-Domino) and radiogenic (U-Pb, Lu-Hf) and stable isotopes (δ18O) to quantify the duration of the different steps of a Wilson cycle. For the purpose of this study, we focus on the Proterozoic Nagssugtoqidian Orogenic Belt (NOB), in the Tasiilaq area, South-East Greenland. Our study reveals that the Nagssugtoqidian Orogen was the result of a complete three stages juvenile crust production (Xjuv) - recycling/reworking sequence: (I) During the 2.60-2.95 Ga period, the Neoarchean Skjoldungen Orogen remobilised basement lithologies formed at TDM 2.91 Ga with progressive increase of the discharge of reworked material (Xjuv from 75% to 50%; δ18O: 4-8.5‰). (II) After a period of crustal stabilization (2.35-2.60 Ga), discrete juvenile material inputs (δ18O: 5-6‰) at TDM 2.35 Ga argue for the formation of an oceanic lithosphere and seafloor spreading over a period of 0.2 Ga (Xjuv from < 25% to 70%). Lateral shortening is set to have started at ca. 2.05 Ga with the accretion of volcanic/magmatic arcs (i.e. Ammassalik Intrusive Complex) and by subduction of small oceanic domains (M1: 520 ± 60 °C at 6.6 ± 1.4 kbar). (III) Continental collision between the North Atlantic

  11. Cognitive Factors that Impact Learning in the Field: Observations from an REU Project on Precambrian Rocks of Yellowstone National Park

    Science.gov (United States)

    Henry, D.; Mogk, D. W.; Goodwin, C.

    2011-12-01

    Field work requires cognitive processing on many different levels, and constitutes a powerful and important learning environment. To be effective and meaningful, the context of field work must be fully understood in terms of key research questions, earlier published work, regional geology, geologic history, and geologic processes. Scale(s) of observation and sample selection methods and strategies must be defined. Logistical decisions must be made about equipment needed, points of access, and navigation in the field. Professional skills such as field note-taking, measuring structural data, and rock descriptions must be employed, including appropriate use of field tools. Interpretations of geologic features in the field must be interpreted through recall of concepts from the geologic knowledge base (e.g. crystallization history of igneous rocks interpreted through phase diagrams). Field workers need to be able to self-monitor and self-regulate their actions (metacognitively), and make adjustments to daily plans as needed. The results of field work must be accurately and effectively communicated to other geoscientists. Personal and professional ethics and values are brought to bear as decisions are made about whether or not the work has been satisfactorily completed at a field site. And, all of this must be done against a back drop of environmental factors that affect the ability to do this work (e.g. inclement weather, bears, impassable landscapes). The simultaneous relevance of all these factors creates a challenging, but rewarding environment for learning on many different scales. During our REU project to study the Precambrian rocks in the back country of Yellowstone National Park (YNP), we considered these cognitive factors in designing our project curriculum. To reduce the "novelty space" of the project a website was developed that described the project goals and expected outcomes, introduced primary literature, and alerted students about the physical demands

  12. Criteria for the recognition and correlation of sandstone units in the Precambrian and Paleozoic-Mesozoic clastic sequence in the near east

    Science.gov (United States)

    Weissbrod, T.; Perath, I.

    A systematic study of the Precambrian and Paleozoic-Mesozoic clastic sequences (Nubian Sandstone) in Israel and Sinai, and a comparative analysis of its stratigraphy in neighbouring countries, has shown that besides the conventional criteria of subdivision (lithology, field appearance, photogeological features, fossil content), additional criteria can be applied, which singly or in mutual conjuction enable the recognition of widespread units and boundaries. These criteria show lateral constancy, and recurrence of a similar vertical sequence over great distances, and are therefore acceptable for the identification of synchronous, region-wide sedimentary units (and consequently, major unconformities). They also enable, once the units are established, to identify detached (not in situ) samples, samples from isolated or discontinous outcrops, borehole material or archive material. The following rock properties were tested and found to be usefuls in stratigraphic interpretation, throughout large distribution areas of the clastic sequence: Landscape, which is basically the response of a particular textural-chemic al aggregate to atmospheric weathering. Characteristic outcrop feature — styles of roundness or massivity, fissuring or fliatin, slope profile, bedding — express a basic uniformity of these platform-type clastics. Colors are often stratigraphically constant over hundreds of kilometers, through various climates and topographies, and express some intrinsic unity of the rock bodies. Grain size and sorting, when cross-plotted, enable to differentiate existing unit. The method requires the analysis of representative numbers of samples. Vertical trends of median grain size and sorting show reversals, typically across unconformities. Feldstar content diminishes from 15-50% in Precambrian-Paleozoic rocks to a mere 5% or less in Mesozoic sandstones — a distinctive regionwide time trend. Dominance of certain feldstar types characterizes Precambrian and Paleozoic

  13. Dominant Lid Tectonics behaviour of continental lithosphere in Precambrian times: Palaeomagnetism confirms prolonged quasi-integrity and absence of supercontinent cycles

    Directory of Open Access Journals (Sweden)

    J.D.A. Piper

    2018-01-01

    Full Text Available Although Plate Tectonics cannot be effectively tested by palaeomagnetism in the Precambrian aeon due to the paucity of high precision poles spanning such a long time period, the possibility of Lid Tectonics is eminently testable because it seeks accordance of the wider dataset over prolonged intervals of time; deficiencies and complexities in the data merely contribute to dispersion. Accordance of palaeomagnetic poles across a quasi-integral continental crust for time periods of up to thousands of millions of years, together with recognition of very long intervals characterised by minimal polar motions (∼2.6–2.0, ∼1.5–1.25 and ∼0.75–0.6 Ga has been used to demonstrate that Lid Tectonics dominated this aeon. The new PALEOMAGIA database is used to refine a model for the Precambrian lid incorporating a large quasi-integral crescentric core running from South-Central Africa through Laurentia to Siberia with peripheral cratons subject to reorganisation at ∼2.1, ∼1.6 and ∼1.1 Ga. The model explains low levels of tidal friction, reduced heat balance, unique petrologic and isotopic signatures, and the prolonged crustal stability of Earth's “Middle Age”, whilst density concentrations of the palaeomagnetic poles show that the centre of the continental lid was persistently focussed near Earth's rotation axis from ∼2.8 to 0.6 Ga. The exception was the ∼2.7–2.2 Ga interval defined by ∼90° polar movements which translated the periphery of the lid to the rotation pole for this quasi-static period, a time characterised by glaciation and low levels of magmatic activity; the ∼2.7 Ga shift correlates with key interval of mid-Archaean crustal growth to some 60–70% of the present volume and REE signatures whilst the ∼2.2 Ga shift correlates with the Lomagundi δ13 C and Great Oxygenation events. The palaeomagnetic signature of breakup of the lid at ∼0.6 Ga is recorded by the world-wide Ediacaran development of passive

  14. Palaeobotanical data for climate change during the late Miocene - early Pliocene in Western Bulgaria

    International Nuclear Information System (INIS)

    Hristova, Viktoria; Ivanov, Dimiter; Bozukov, Vladimir

    2015-01-01

    The Coexistence Approach (CA) analysis was applied to plant macro- and microfossils from the Late Miocene to Early Pliocene sites in western Bulgaria to obtain quantitative climate data and reconstruct climate dynamics. Calculated new values for the Sofia macro flora confirmed a warm-temperate and humid climate with mean annual temperature (MAT) between 12–170C, mean temperature of the warmest month (WMT) 23.6–280C, mean temperature of the coldest month (CMT) 0–50C and mean annual precipitation (MAP) 843–1179 mm. This is consistent with the climatic parameters obtained from the microflora – MAT 13.6–16, WMT 23.6–27.9, CMT 3.7–6 and MAP 803–1308mm. All presented data are in good accordance with other regional palaeoclimate reconstructions from Bulgarian and Europaean floras. Key words: Late Miocene–Early Pliocene, palaeoclimate, Sofia Basin

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-15

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

  16. Assessing the fidelity of marine vertebrate microfossil δ18O signatures and their potential for palaeo-ecological and -climatic reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Roelofs, Brett; Barham, Milo; Cliff, John; Joachimski, Michael; Martin, Laure; Trinajstic, Kate

    2017-01-01

    Conodont biogenic apatite has become a preferred analytical target for oxygen isotope studies investigating ocean temperature and palaeoclimate change in the Palaeozoic. Despite the growing application in geochemical based palaeoenvironmental reconstructions, the paucity or absence of conodont fossils in certain facies necessitates greater flexibility in selection of robust oxygen bearing compounds for analysis. Microvertebrates offer a potential substitute for conodonts from the middle Palaeozoic. Microvertebrate bioapatite is particularly advantageous given a fossil record extending to the present with representatives across freshwater to fully marine environments, thus widening the scope of oxygen isotope studies on bioapatite. However, significant tissue heterogeneity within vertebrates and differential susceptibility of these tissues to diagenetic alteration have been raised as potential problems affecting the reliability of the oxygen isotope ratios as palaeoclimate proxies. Pristine microvertebrate and co-occurring conodont fossils from the Late Devonian and Early Carboniferous of the Lennard Shelf, Canning Basin, Western Australia, were analysed using bulk (gas isotope ratio mass spectrometry) and in-situ (secondary ion mass spectrometry) methodologies, with the latter technique allowing investigation of specific tissues within vertebrate elements. The δ18Oconodont results may be interpreted in terms of palaeolatitudinally and environmentally sensible palaeotemperatures and provide a baseline standard for comparison against δ18Omicrovertebrate values. Despite an absence of obvious diagenetic influences, GIRMS of microvertebrate denticles yielded δ18O values depleted by 2-4 ‰ relative to co-occurring conodonts. SIMS analysis of hypermineralised tissues in both scales and teeth produced δ18O values comparable with those of associated conodonts. The susceptibility of porous phosphatic fossil tissues to microbial activity, fluid interaction and

  17. Extreme alkali bicarbonate- and carbonate-rich fluid inclusions in granite pegmatite from the Precambrian Rønne granite, Bornholm Island, Denmark

    Science.gov (United States)

    Thomas, Rainer; Davidson, Paul; Schmidt, Christian

    2011-02-01

    Our study of fluid and melt inclusions in quartz and feldspar from granite pegmatite from the Precambrian Rønne granite, Bornholm Island, Denmark revealed extremely alkali bicarbonate- and carbonate-rich inclusions. The solid phases (daughter crystals) are mainly nahcolite [NaHCO3], zabuyelite [Li2CO3], and in rare cases potash [K2CO3] in addition to the volatile phases CO2 and aqueous carbonate/bicarbonate solution. Rare melt inclusions contain nahcolite, dawsonite [NaAl(CO3)(OH)2], and muscovite. In addition to fluid and melt inclusions, there are primary CO2-rich vapor inclusions, which mostly contain small nahcolite crystals. The identification of potash as a naturally occurring mineral would appear to be the first recorded instance. From the appearance of high concentrations of these carbonates and bicarbonates, we suggest that the mineral-forming media were water- and alkali carbonate-rich silicate melts or highly concentrated fluids. The coexistence of silicate melt inclusions with carbonate-rich fluid and nahcolite-rich vapor inclusions indicates a melt-melt-vapor equilibrium during the crystallization of the pegmatite. These results are supported by the results of hydrothermal diamond anvil cell experiments in the pseudoternary system H2O-NaHCO3-SiO2. Additionally, we show that boundary layer effects were insignificant in the Bornholm pegmatites and are not required for the origin of primary textures in compositionally simple pegmatites at least.

  18. Post-early cretaceous landform evolution along the western margin of the banca~nnia trough, western nsw

    Science.gov (United States)

    Gibson, D.L.

    2000-01-01

    Previously undated post-Devonian sediments outcropping north of Fowlers Gap station near the western margin of the Bancannia Trough are shown by plant macro- and microfossil determinations to be of Early Cretaceous (most likely Neocomian and/or Aptian) age, and thus part of the Eromanga Basin. They are assigned to the previously defined Telephone Creek Formation. Study of the structural configuration of this unit and the unconformably underlying Devonian rocks suggests that the gross landscape architecture of the area results from post-Early Cretaceous monoclinal folding along blind faults at the western margin of the trough, combined with the effects of differential erosion. This study shows that, while landscape evolution in the area has been dynamic, the major changes that have occurred are on a geological rather than human timescale.

  19. U-Pb zircon geochronology of Late Devonian to Early Carboniferous extension-related silicic volcanism in the northern New England Fold Belt

    International Nuclear Information System (INIS)

    Bryan, S.E.; Holcombe, R.J.; Fielding, C.R.; Allen, C.M.

    2004-01-01

    Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of zircons confirm a Late Devonian to Early Carboniferous age (ca 360-350 Ma) for silicic volcanic rocks of the Campwyn Volcanics and Yarrol terrane of the northern New England Fold Belt (Queensland). These rocks are coeval with silicic volcanism recorded elsewhere in the fold belt at this time (Connors Arch, Drummond Basin). The new U-Pb zircon ages, in combination with those from previous studies, show that silicic magmatism was both widespread across the northern New England Fold Belt (>250 000 km 2 and >500 km inboard of plate margin) and protracted, occurring over a period of -15 million years. Zircon inheritance is commonplace in the Late Devonian - Early Carboniferous volcanics, reflecting anatectic melting and considerable reworking of continental crust. Inherited zircon components range from ca 370 to ca 2050 Ma, with Middle Devonian (385-370 Ma) zircons being common to almost all dated units. Precambrian zircon components record either Precambrian crystalline crust or sedimentary accumulations that were present above or within the zone of magma formation This contrasts with a lack of significant zircon inheritance in younger Permo-Carboniferous igneous rocks intruded through,and emplaced on top of, the Devonian-Carboniferous successions. The inheritance data and location of these volcanic rocks at the eastern margins of the northern New England Fold Belt, coupled with Sr-Nd, Pb isotopic data and depleted mantle model ages for Late Palaeozoic and Mesozoic magmatism, imply that Precambrian mafic and felsic crustal materials (potentially as old as 2050 Ma), or at the very least Lower Palaeozoic rocks derived from the reworking of Precambrian rocks, comprise basement to the eastern parts of the fold belt. This crustal basement architecture may be a relict from the Late Proterozoic breakup of the Rodinian supercontinent. Copyright (2004) Geological Society of Australia

  20. Origin and tectonic evolution of early Paleozoic arc terranes abutting the northern margin of North China Craton

    Science.gov (United States)

    Zhou, Hao; Pei, Fu-Ping; Zhang, Ying; Zhou, Zhong-Biao; Xu, Wen-Liang; Wang, Zhi-Wei; Cao, Hua-Hua; Yang, Chuan

    2017-12-01

    The origin and tectonic evolution of the early Paleozoic arc terranes abutting the northern margin of the North China Craton (NCC) are widely debated. This paper presents detrital zircon U-Pb and Hf isotopic data of early Paleozoic strata in the Zhangjiatun arc terrane of central Jilin Province, northeast (NE) China, and compares them with the Bainaimiao and Jiangyu arc terranes abutting the northern margin of the NCC. Detrital zircons from early Paleozoic strata in three arc terranes exhibit comparable age groupings of 539-430, 1250-577, and 2800-1600 Ma. The Paleoproterozoic to Neoarchean ages and Hf isotopic composition of the detrital zircons imply the existence of the Precambrian fragments beneath the arc terranes. Given the evidences from geology, igneous rocks, and detrital zircons, we proposed that the early Paleozoic arc terranes abutting the northern margin of the NCC are a united arc terrane including the exotic Precambrian fragments, and these fragments shared a common evolutionary history from Neoproterozoic to early-middle Paleozoic.

  1. Precambrian supercontinents, glaciations, atmospheric oxygenation, metazoan evolution and an impact that may have changed the second half of Earth history

    Directory of Open Access Journals (Sweden)

    Grant M. Young

    2013-05-01

    Full Text Available In more than 4 Ga of geological evolution, the Earth has twice gone through extreme climatic perturbations, when extensive glaciations occurred, together with alternating warm periods which were accompanied by atmospheric oxygenation. The younger of these two episodes of climatic oscillation preceded the Cambrian “explosion” of metazoan life forms, but similar extreme climatic conditions existed between about 2.4 and 2.2 Ga. Over long time periods, changing solar luminosity and mantle temperatures have played important roles in regulating Earth's climate but both periods of climatic upheaval are associated with supercontinents. Enhanced weathering on the orogenically and thermally buoyed supercontinents would have stripped CO2 from the atmosphere, initiating a cooling trend that resulted in continental glaciation. Ice cover prevented weathering so that CO2 built up once more, causing collapse of the ice sheets and ushering in a warm climatic episode. This negative feedback loop provides a plausible explanation for multiple glaciations of the Early and Late Proterozoic, and their intimate association with sedimentary rocks formed in warm climates. Between each glacial cycle nutrients were flushed into world oceans, stimulating photosynthetic activity and causing oxygenation of the atmosphere. Accommodation for many ancient glacial deposits was provided by rifting but escape from the climatic cycle was predicated on break-up of the supercontinent, when flooded continental margins had a moderating influence on weathering. The geochemistry of Neoproterozoic cap carbonates carries a strong hydrothermal signal, suggesting that they precipitated from deep sea waters, overturned and spilled onto continental shelves at the termination of glaciations. Paleoproterozoic (Huronian carbonates of the Espanola Formation were probably formed as a result of ponding and evaporation in a hydrothermally influenced, restricted rift setting. Why did metazoan

  2. ASSESSMENT OF THE INFLUENCE OF MODERN CRUSTAL MOVEMENTS AND THE RECENTLY ACTIVATED PRECAMBRIAN STRUCTURAL PLAN ON THE RELIEF OF THE LAKE LADOGA REGION (THE SOUTHEASTERN BALTIC SHIELD

    Directory of Open Access Journals (Sweden)

    A. O. Agibalov

    2017-01-01

    Full Text Available This paper describes the influence of modern crustal movements and the recently activated Precambrian structural plan on the relief of theLakeLadogaregion. It presents the results of comprehensive studies, including processing of the regional geological and geomorphological data by the modern methods, as the major novelty of our work. The solutions of earthquake focal mechanisms suggest the current subhorizontal NW compression in the study area. Based on the computer simulation by the Roxar software, we have identified areas wherein new fractures are most likely to occur, determined the dominant directions of such fractures, and revealed the areas of intense vertical movements in the given stress state. The input database included a digital model of the relief and the spatial patterns of ancient faults represented by large-size inhomogeneities influencing the stress field. Strain values were estimated from the horizontal displacements recorded by the International GPS Service for Geodynamics (IGS and the GPS networks in theRepublicofKareliaand the southeastern regions ofFinland. Using the LESSA software, we have estima­ted the relief orientation characteristics: the density of lineaments, and elongation lines, which are indicative of the changes in the dominant directions of the strike of the lineaments (‘hatches’ in the study area. By interpreting the satellite images and the topographic maps (scale 1:20000, we reveal a number of geological structures, such as gra­nite-gneiss domes and large-size faults, which are directly reflected in the relief. The study results give grounds to establish an indirect relationship between the relief and the modern field of deformation: the areas with high strain values correspond to the areas with steep slopes. The computer simulation data show a NE-trending linear zone with the increased amplitudes of vertical movements. This zone occupies the region along the NW shoreLakeLadoga. In the block

  3. Oxygen isotope exchange kinetics of mineral pairs in closed and open systems: Applications to problems of hydrothermal alteration of igneous rocks and Precambrian iron formations

    Science.gov (United States)

    Gregory, R.T.; Criss, R.E.; Taylor, H.P.

    1989-01-01

    heat-balance constraints, we can utilize the 18O 16O data on natural mineral assemblages to calculate the kinetic rate constants (k's) and the effective diffusion constants (D's) for mineral-H2O exchange: these calculated values (kqtz ??? 10-14, kfeld ??? 10-13-10-12) agree with experimental determinations of such constants. In nature, once the driving force or energy source for the external infiltrating fluid phase is removed, the disequilibrium mineral-pair arrays will either: (1) remain "frozen" in their existing state, if the temperatures are low enough, or (2) re-equilibrate along specific closed-system exchange vectors determined solely by the temperature path and the mineral modal proportions. Thus, modal mineralogical information is a particularly important parameter in both the open- and closed-system scenarios, and should in general always be reported in stable-isotopic studies of mineral assemblages. These concepts are applied to an analysis of 18O 16O systematics of gabbros (Plagioclase-clinopyroxene and plagioclase-amphibole pairs), granitic plutons (quartz-feldspar pairs), and Precambrian siliceous iron formations (quartz-magnetite pairs). In all these examples, striking regularities are observed on ??-?? and ??-?? plots, but we point out that ??-?? plots have many advantages over their equivalent ??-?? diagrams, as the latter are more susceptible to misinterpretation. Using the equations developed in this study, these regularities can be interpreted to give semiquantitative information on the exchange histories of these rocks subsequent to their formation. In particular, we present a new interpretation indicating that Precambrian cherty iron formations have in general undergone a complex fluid exchange history in which the iron oxide (magnetite precursor?) has exchanged much faster with low-temperature (< 400??C) fluids than has the relatively inert quartz. ?? 1989.

  4. Petrology, geochemistry and zirconology of impure calcite marbles from the Precambrian metamorphic basement at the southeastern margin of the North China Craton

    Science.gov (United States)

    Liu, Yi-Can; Zhang, Pin-Gang; Wang, Cheng-Cheng; Groppo, Chiara; Rolfo, Franco; Yang, Yang; Li, Yuan; Deng, Liang-Peng; Song, Biao

    2017-10-01

    Impure calcite marbles from the Precambrian metamorphic basement of the Wuhe Complex, southeastern margin of the North China Craton, provide an exceptional opportunity to understand the depositional processes during the Late Archean and the subsequent Palaeoproterozoic metamorphic evolution of one of the oldest cratons in the world. The studied marbles are characterized by the assemblage calcite + clinopyroxene + plagioclase + K-feldspar + quartz + rutile ± biotite ± white mica. Based on petrography and geochemistry, the marbles can be broadly divided into two main types. The first type (type 1) is rich in REE with a negative Eu anomaly, whereas the second type (type 2) is relatively poor in REE with a positive Eu anomaly. Notably, all marbles exhibit remarkably uniform REE patterns with moderate LREE/HREE fractionation, suggesting a close genetic relationship. Cathodoluminescence imaging, trace elements and mineral inclusions reveal that most zircons from two dated samples display distinct core-rim structures. Zircon cores show typical igneous features with oscillatory growth zoning and high Th/U ratios (mostly in the range 0.3-0.7) and give ages of 2.53 - 2.48 Ga, thus dating the maximum age of deposition of the protolith. Zircon rims overgrew during granulite-facies metamorphism, as evidenced by calcite + clinopyroxene + rutile + plagioclase + quartz inclusions, by Ti-in-zircon temperatures in the range 660-743 °C and by the low Th/U (mostly marbles are ascribed to syn-depositional felsic hydrothermal activity which occurred at 2.53 - 2.48 Ga. Our results, together with other published data and the inferred tectonic setting, suggest that the marbles' protolith is an impure limestone, rich in detrital silicates of igneous origin, deposited in a back-arc basin within an active continental margin during the late Archean and affected by synchronous high-T hydrothermalism at the southeastern margin of the North China Craton.

  5. Eocene cooling linked to early flow across the Tasmanian Gateway.

    Science.gov (United States)

    Bijl, Peter K; Bendle, James A P; Bohaty, Steven M; Pross, Jörg; Schouten, Stefan; Tauxe, Lisa; Stickley, Catherine E; McKay, Robert M; Röhl, Ursula; Olney, Matthew; Sluijs, Appy; Escutia, Carlota; Brinkhuis, Henk

    2013-06-11

    The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52-50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica from 34 Ma onward. Whereas early studies attributed the Eocene transition from greenhouse to icehouse climates to the tectonic opening of Southern Ocean gateways, more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations (e.g., CO2). However, the scarcity of field data has prevented empirical evaluation of these hypotheses. We present marine microfossil and organic geochemical records spanning the early-to-middle Eocene transition from the Wilkes Land Margin, East Antarctica. Dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound Antarctic Counter Current began ~49-50 Ma through a southern opening of the Tasmanian Gateway. This early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling (2-4 °C), evidenced by biomarker- and pollen-based paleothermometry. We interpret that the westbound flowing current flow across the Tasmanian Gateway resulted in cooling of Antarctic surface waters and coasts, which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes. Although atmospheric CO2 forcing alone would provide a more uniform middle Eocene cooling, the opening of the Tasmanian Gateway better explains Southern Ocean surface water and global deep ocean cooling in the apparent absence of (sub-) equatorial cooling.

  6. Proterozoic and early Cambrian protists: evidence for accelerating evolutionary tempo

    Science.gov (United States)

    Knoll, A. H.

    1994-01-01

    In rocks of late Paleoproterozoic and Mesoproterozoic age (ca. 1700-1000 million years ago), probable eukaryotic microfossils are widespread and well preserved, but assemblage and global diversities are low and turnover is slow. Near the Mesoproterozoic-Neoproterozoic boundary (1000 million years ago), red, green, and chromophytic algae diversified; molecular phylogenies suggest that this was part of a broader radiation of "higher" eukaryotic phyla. Observed diversity levels for protistan microfossils increased significantly at this time, as did turnover rates. Coincident with the Cambrian radiation of marine invertebrates, protistan microfossils again doubled in diversity and rates of turnover increased by an order of magnitude. Evidently, the Cambrian diversification of animals strongly influenced evolutionary rates, within clades already present in marine communities, implying an important role for ecology in fueling a Cambrian explosion that extends across kingdoms.

  7. Late Paleogene-early Neogene dinoflagellate cyst biostratigraphy of the eastern Equatorial Atlantic

    Science.gov (United States)

    Awad, Walaa K.; Oboh-Ikuenobe, Francisca E.

    2018-04-01

    Six dinoflagellate cyst biozones (zone 1-zone 5, subzones 1a and 1b) are recognized in the late Paleogene-early Neogene interval of the Ocean Drilling Program (ODP) Site 959 (Hole 959 A), Côte d'Ivoire-Ghana Transform Margin in the eastern Equatorial Atlantic. The biozones are based on palynological analysis of 30 samples covering a 273.2-m interval with generally fair preservation and good to poor recovery. We propose a new age of Late Eocene (Priabonian) for subunit IIB as opposed to the previously published mid-Early Oligocene age (middle Rupelian). This age assignment is mainly based on the presence of Late Eocene marker taxa, such as Hemiplacophora semilunifera and Schematophora speciosa in the lower part of the studied interval. We also document for the first time a hiatus event within dinoflagellate cyst zone 3, based on the last occurrences of several taxa. This interval is assigned to an Early Miocene age and is barren of other microfossils. Furthermore, we propose new last occurrences for two species. The last occurrence of Cerebrocysta bartonensis is observed in the late Aquitanian-early Burdigalian in this study vs. Priabonian-early Rupelian in mid and high latitude regions. Also, the last occurrence of Chiropteridium galea extends to the latest Early Miocene (Burdigalian) in ODP Hole 959 A; this event was previously identified in other studies as Chattian in equatorial regions, and Aquitanian in the Northern Hemisphere mid-latitudes. We suspect that these differences are due to physical (offshore vs. nearshore) and latitudinal locations of the areas studied.

  8. Early discontinuation

    DEFF Research Database (Denmark)

    Hansen, Dorte Gilså; Felde, Lina; Gichangi, Anthony

    2007-01-01

    prevalence and rate of early discontinuation of different drugs consisting of, in this study, lipid-lowering drugs, antihypertensive drugs, antidepressants, antidiabetics and drugs against osteoporosis. Material and methods This was a register study based on prescription data covering a 4-year period...... and consisting of 470,000 citizens. For each practice and group of drug, a 1-year prevalence for 2002 and the rate of early discontinuation among new users in 2002-2003 were estimated. Early discontinuation was defined as no prescriptions during the second half-year following the first prescription....... There was a positive association between the prevalence of prescribing for the specific drugs studied (antidepressants, antidiabetics, drugs against osteoporosis and lipid-lowering drugs) and early discontinuation (r = 0.29 -0.44), but not for anti-hypertensive drugs. The analysis of the association between prevalence...

  9. Early literacy

    DEFF Research Database (Denmark)

    Jensen, Anders Skriver

    2012-01-01

    This paper discusses findings from the Danish contribution to the EASE project, a European research project running from 2008 to 2010 on early literacy in relation to the transition from childcare to school. It explores a holistic, inclusive approach to early literacy that resists a narrow...... and schools. The paper also draws on Gee’s (2001, 2003, 2004, 2008) sociocultural approach to literacy, and Honneth’s (2003, 2006) concept of recognition. Emphasizing participation and recognition as key elements, it claims that stakeholders in early liter- acy must pay attention to how diverse early literacy...... opportunities empower children, especially when these opportunities are employed in a project-based learning environ- ment in which each child is able to contribute to the shared literacy events....

  10. Origin of the Early Sial Crust and U-Pb Isotope-Geochemical Heterogeneity of the Earth's Mantle

    Science.gov (United States)

    Mishkin, M. A.; Nozhkin, A. D.; Vovna, G. M.; Sakhno, V. G.; Veldemar, A. A.

    2018-02-01

    It is shown that presence of the Early Precambrian sial crust in the Indo-Atlantic segment of the Earth and its absence in the Pacific has been caused by geochemical differences in the mantle underlying these segments. These differences were examined on the basis of Nd-Hf and U-Pb isotopes in modern basalts. The U-Pb isotope system is of particular interest, since uranium is a member of a group of heat-generating radioactive elements providing heat for plumes. It is shown that in the Indo-Atlantic segment, a distribution of areas of the modern HIMU type mantle is typical, while it is almost completely absent in the Pacific segment. In the Archean, in the upper HIMU type paleo-mantle areas, plume generation and formation of the primordial basic crust occurred; this was followed by its remelting resulting in the appearance of an early sial crust forming cratons of the Indo-Atlantic segment.

  11. Isotopic investigation of the late neoproterozoic and early cambrian carbon cycle on the northern Yangtze platform, south China

    International Nuclear Information System (INIS)

    Guo Qingjun; Liu Congqiang; Harald Strauss; Tatiana Goldberg

    2003-01-01

    The Precambrian-Cambrian transition is one of the critical time intervals in Earth history. Profound geotectonic, climatic and biological changes occur during the late Neoproterozoic and its transition into the early Cambrian. This study has researched on paired carbonate and organic carbon isotope determinations from Nanjiang, Sichuan Province of the Yangtze Platform, and provided a preliminary geochemical explanation for environmental variations and bio-events observed on the northern Yangtze Platform during the Precambrian-Cambrian transitional interval and their causal relationship. Organic carbon isotopic compositions on sediments vary from -35.8 to -30.1‰ at Nanjiang section; carbonate carbon isotopic compositions change between -3.5 and +0.5‰. Various carbon and sulphur isotopic compositions, different pyrite and organic matter content reflect changing environment and burial of organic matter in the Dengying Fm., the lower and upper part of Niutitang Fm. Anoxic conditions result in widespread preservation of organic rich sediments and pyrites in the black shales on the Yangtze Platform. (authors)

  12. EARLY STAGE OF THE CENTRAL ASIAN OROGENIC BELT BUILDING: EVIDENCES FROM THE SOUTHERN SIBERIAN CRATON

    Directory of Open Access Journals (Sweden)

    D. P. Gladkochub

    2017-01-01

    Full Text Available The origin of the Central-Asian Orogenic Belt (CAOB, especially of its northern segment nearby the southern margin of the Siberian craton (SC is directly related to development and closure of the Paleo-Asian Ocean (PAO. Signatures of early stages of the PAO evolution are recorded in the Late Precambrian sedimentary successions of the Sayan-Baikal-Patom Belt (SBPB on the southern edge of SC. These successions are spread over 2000 km and can be traced along this edge from north-west (Sayan area to south-east (Baikal area and further to north-east (Patom area. Here we present the synthesis of all available and reliable LA-ICP-MS U-Pb geochronological studies of detrital zircons from these sedimentary successions.

  13. Extent and character of early tertiary penetrative deformation, Sonora, Northwest Mexico

    Science.gov (United States)

    Anderson, T. H.

    1985-01-01

    Reconnaissance field work has led to the recognition of extensive Early Tertiary gneiss and schist which are distinguished by weakly developed to highly conspicous northeast to east-trending stretching lineation commonly accompanied by low-dipping foliation. This structural fabric has been imposed on Precambrian to Paleogene rocks. Regionally, minimum ages of deformation are based upon interpreted U-Pb isotopic ages from suites of cogenetic zircon from the Paleogene orthogneiss. Locally, the interpreted ages indicate that ductile deformation continued as late as Oligocene (Anderson and others, 1980; Silver and Anderson, 1984). The consistency of the deformational style is such that, although considerable variation in intensity exists, the fabric can be recognized and correlated in rocks away from the Paleogene orthogneiss.

  14. A micropalaeontological and palynological insight into Early Carboniferous floodplain environments

    Science.gov (United States)

    Bennett, Carys; Kearsey, Timothy; Davies, Sarah; Millward, David; Marshall, John; Reeves, Emma

    2016-04-01

    Romer's Gap, the interval following the end Devonian mass extinction, is traditionally considered to be depauperate in tetrapod and fish fossils. A major research project (TW:eed -Tetrapod World: early evolution and diversification) focusing on the Tournaisian Ballagan Formation of Scotland is investigating how early Carboniferous ecosystems rebuilt following the extinction. A multi-proxy approach, combining sedimentology, micropalaeontology and palynology, is used to investigate the different floodplain environments in which tetrapods, fish, arthropods and molluscs lived. The formation is characterised by an overbank facies association of siltstone, sandstone and palaeosols, interbedded with dolostone and evaporite units, and cut by fluvial sandstone facies associations of fining-upwards conglomerate lags, cross-bedded sandstone and rippled siltstone. Macrofossils are identified from 326 horizons within a 520 metre thick Ballagan Formation field section at Burnmouth, near Berwick-upon-Tweed, Scottish Borders. Common fauna are ostracods, bivalves, arthropods, sarcopterygians, dipnoans, acanthodians, tetrapods and chondrichthyans. Quantitative microfossil picking of the three sedimentary rock types in which tetrapods occur was undertaken to gain further insight into the palaeoecology. The sediments are; 1) laminated grey siltstones, deposited in floodplain lakes; 2) sandy siltstones, grey siltstones with millimetre size clasts. 71% of these beds overlie palaeosols or desiccated surfaces and are formed in small-scale flooding events; 3) conglomerates, mostly lags at the base of thick sandstones, with centimetre sized siltstone, sandstone and dolostone clasts. Grey siltstones contain a microfauna of common plant fragments, megaspores and sparse actinopterygian and rhizodont fragments. Sandy siltstones have the highest fossil diversity and contain microfossil fragments of plants, megaspores, charcoal, ostracods, actinopterygians, rhizodonts, eurypterids and rarer non

  15. Late Precambrian Balkan-Carpathian ophiolite — a slice of the Pan-African ocean crust?: geochemical and tectonic insights from the Tcherni Vrah and Deli Jovan massifs, Bulgaria and Serbia

    Science.gov (United States)

    Savov, Ivan; Ryan, Jeff; Haydoutov, Ivan; Schijf, Johan

    2001-10-01

    The Balkan-Carpathian ophiolite (BCO), which outcrops in Bulgaria, Serbia and Romania, is a Late Precambrian (563 Ma) mafic/ultramafic complex unique in that it has not been strongly deformed or metamorphosed, as have most other basement sequences in Alpine Europe. Samples collected for study from the Tcherni Vrah and Deli Jovan segments of BCO include cumulate dunites, troctolites, wehrlites and plagioclase wehrlites; olivine and amphibole-bearing gabbros; anorthosites; diabases and microgabbros; and basalts representing massive flows, dikes, and pillow lavas, as well as hyaloclastites and umbers (preserved sedimentary cover). Relict Ol, Cpx and Hbl in cumulate peridotites indicate original orthocumulate textures. Plagioclase in troctolites and anorthosites range from An60 to An70. Cumulate gabbro textures range from ophitic to poikilitic, with an inferred crystallization order of Ol-(Plag+Cpx)-Hbl. The extrusive rocks exhibit poikilitic, ophitic and intersertal textures, with Cpx and/or Plag (Oligoclase-Andesine) phenocrysts. The major opaques are Ti-Magnetite and Ilmenite. The metamorphic paragenesis in the mafic samples is Chl-Trem-Ep, whereas the ultramafic rocks show variable degrees of serpentinization, with lizardite and antigorite as dominant phases. Our samples are compositionally and geochemically similar to modern oceanic crust. Major element, trace element and rare earth element (REE) signatures in BCO basalts are comparable to those of MORB. In terms of basalt and dike composition, the BCO is a 'high-Ti' or 'oceanic' ophiolite, based on the classification scheme of Serri [Earth Planet. Sci. Lett. 52 (1981) 203]. Our petrologic and geochemical results, combined with the tectonic position of the BCO massifs (overlain by and in contact with Late Cambrian island arc and back-arc sequences), suggest that the BCO may have formed in a mid-ocean ridge setting. If the BCO records the existence of a Precambrian ocean basin, then there may be a relationship

  16. Early Math.

    Science.gov (United States)

    Van Nuys, Ute Elisabeth

    1986-01-01

    Presents reviews of the following mathematics software designed to teach young children counting, number recognition, visual discrimination, matching, addition, and subtraction skills; Stickybear Numbers, Learning with Leeper, Getting Ready to Read and Add, Counting Parade, Early Games for Young Children, Charlie Brown's 1,2,3's, Let's Go Fishing,…

  17. Paleomagnetism of Devonian dykes in the northern Kola Peninsula and its bearing on the apparent polar wander path of Baltica in the Precambrian

    Science.gov (United States)

    Veselovskiy, Roman V.; Bazhenov, Mikhail L.; Arzamastsev, Andrey A.

    2016-04-01

    Mafic dykes and large alkaline and carbonatite intrusions of Middle-Late Devonian age are widespread on the Kola Peninsula in NE Fennoscandia. These magmatic rocks are well characterized with petrographic, geochemical and geochronological data but no paleomagnetic results have been reported yet. We studied dolerite dykes from the northern part of the Peninsula and isolated three paleomagnetic components in these rocks. A low-temperature component is aligned along the present-day field, while a major constituent of natural remanent magnetization is an intermediate-temperature component (Decl. = 79.6°, Inc. = 78.5°, α95 = 5,9°, N = 17 sites) that is present in most Devonian dykes but is found in some baked metamorphic rocks and Proterozoic dykes too. Finally, a primary Devonian component could be reliably isolated from two dykes only. Rock-magnetic studies point to presumably primary low-Ti titanomagnetite and/or pure magnetite as the main remanence carriers but also reveal alteration of the primary minerals and the formation of new magnetic phases. The directions of a major component differ from the Middle Paleozoic reference data for Baltica but closely match those for the 190 ± 10 Ma interval recalculated from the apparent polar wander path of the craton. We assume that this Early Jurassic component is a low-temperature overprint of chemical origin. The main impact of the new results is not to mid-Paleozoic or Early Mesozoic times but to much older epochs. Analysis of paleomagnetic data shows that the directionally similar remanences are present in objects with the ages ranging from 500 Ma to 2 Ga over entire Fennoscandia. Hence we argue that an Early Jurassic remagnetization is of regional extent but cannot link it to a certain process and a certain tectonic event. If true, this hypothesis necessitates a major revision of the APWP for Baltica over a wide time interval.

  18. Recognition of Cretaceous, Paleocene, and Neogene tectonic reactivation through apatite fission-track analysis in Precambrian areas of southeast Brazil: association with the opening of the south Atlantic Ocean

    Science.gov (United States)

    Tello Saenz, C. A.; Hackspacher, P. C.; Hadler Neto, J. C.; Iunes, P. J.; Guedes, S.; Ribeiro, L. F. B.; Paulo, S. R.

    2003-01-01

    Apatite fission-track analysis was used for the determination of thermal histories and ages in Precambrian areas of southeast Brazil. Together with geological and geomorphologic information, these ages enable us to quantify the thermal histories and timing of Mesozoic and Cenozoic epirogenic and tectonic processes. The collected samples are from different geomorphologic blocks: the high Mantiqueira mountain range (HMMR) with altitude above 1000 m, the low Mantiqueira mountain range (LMMR) under 1000 m, the Serra do Mar mountain range (SMMR), the Jundiaí and Atlantic Plateaus, and the coastline, all of which have distinct thermal histories. During the Aptian (˜120 Ma), there was an uplift of the HMMR, coincident with opening of the south Atlantic Ocean. Its thermal history indicates heating (from ˜60 to ˜80 °C) until the Paleocene, when rocks currently exposed in the LMMR reached temperatures of ˜100 °C. In this period, the Serra do Mar rift system and the Japi erosion surface were formed. The relief records the latter. During the Late Cretaceous, the SMMR was uplifted and probably linked to its origin; in the Tertiary, it experienced heating from ˜60 to ˜90 °C, then cooling that extends to the present. The SMMR, LMMR, and HMMR were reactivated mainly in the Paleocene, and the coastline during the Paleogene. These processes are reflected in the sedimentary sequences and discordances of the interior and continental margin basins.

  19. Preliminary integration study of Precambrian with tectonic events in Brazilian sedimentary basins (Republication); Estudo preliminar de integracao do Pre-Cambriano com os eventos tectonicos das bacias sedimentares brasileiras (Republicacao)

    Energy Technology Data Exchange (ETDEWEB)

    Cordani, Umberto G.; Neves, Benjamim B. Brito; Fuck, Reinhard A.; Porto, Roberto; Thomaz Filho, Antonio; Cunha, Francisco M. Bezerra da

    2008-11-15

    The various successive episodes of vertical cratogenic evolution modelling the geo tectonic features of the basement were correlated with the internal structure, shape, origin and geologic evolution of the sedimentary basin. A systematic petrologic and geochronological investigation of all available drill core samples was carried out, and the pertinent geophysical data regarding basement structure were taken into consideration. Specific geo tectonic analyses, were carried out along the borders of the sedimentary basins, within the adjacent basement. The main boundaries between Precambrian tectonic provinces, the main tectonic sutures with polycyclic evolution, and the ancient intracratonic rifts were identified wherever possible. Their extensions under the sedimentary basins were inferred, corroboration being sought from structural information and data obtained from the drill core samples. It was found that many of the identified basement discontinuities had a direct influence on the depositional history of each of the sedimentary basins, demonstrating the distinct tectonic inheritance. The subject was treated on a reconnaissance scale, 1:1.000.000 or smaller,owing to its complexity. (author)

  20. Early Neogene unroofing of the Sierra Nevada de Santa Marta along the Bucaramanga -Santa Marta Fault

    Science.gov (United States)

    Piraquive Bermúdez, Alejandro; Pinzón, Edna; Bernet, Matthias; Kammer, Andreas; Von Quadt, Albrecht; Sarmiento, Gustavo

    2016-04-01

    Plate interaction between Caribbean and Nazca plates with Southamerica gave rise to an intricate pattern of tectonic blocks in the Northandean realm. Among these microblocks the Sierra Nevada de Santa Marta (SNSM) represents a fault-bounded triangular massif composed of a representative crustal section of the Northandean margin, in which a Precambrian to Late Paleozoic metamorphic belt is overlain by a Triassic to Jurassic magmatic arc and collateral volcanic suites. Its western border fault belongs to the composite Bucaramanga - Santa Marta fault with a combined left lateral-normal displacement. SE of Santa Marta it exposes remnants of an Oligocene marginal basin, which attests to a first Cenoizoic activation of this crustal-scale lineament. The basin fill consists of a sequence of coarse-grained cobble-pebble conglomerates > 1000 m thick that unconformably overlay the Triassic-Jurassic magmatic arc. Its lower sequence is composed of interbedded siltstones; topwards the sequence becomes dominated by coarser fractions. These sedimentary sequences yields valuable information about exhumation and coeval sedimentation processes that affected the massif's western border since the Upper Eocene. In order to analyse uplifting processes associated with tectonics during early Neogene we performed detrital zircon U-Pb geochronology, detrital thermochronology of zircon and apatites coupled with the description of a stratigraphic section and its facies composition. We compared samples from the Aracataca basin with analog sequences found at an equivalent basin at the Oca Fault at the northern margin of the SNSM. Our results show that sediments of both basins were sourced from Precambrian gneisses, along with Mesozoic acid to intermediate plutons; sedimentation started in the Upper Eocene-Oligocene according to palynomorphs, subsequently in the Upper Oligocene a completion of Jurassic to Cretaceous sources was followed by an increase of Precambrian input that became the dominant

  1. Micropaleontology and palaeoclimate during the early Cretaceous in the Lishu depression, Songliao basin, Northeast China

    Directory of Open Access Journals (Sweden)

    Wei Yan

    2017-01-01

    Full Text Available Diverse and abundant microfossils, such as palynomorphs, algae and Ostracoda, were collected from lower Cretaceous strata of Lishu depression, located in southeastern Songliao basin, and were identified and classified in order to provide relevant, detailed records for paleoclimate research. The early Cretaceous vegetation and climate of southeastern Songliao basin have been inferred from the analysis of palynomorph genera, algae and Ostracoda of the LS1 and SW110 wells. The lower Cretaceous strata include, in ascending stratigraphic order, the Shahezi, Yingcheng and Denglouku formations. Palynological assemblages for each formation, based on biostratigraphic and statistical analyses, provide an assessment of their longitudinal variations. During deposition of the Shahezi Formation, the climate was mid-subtropical. Vegetation consisted of coniferous forest and herbage. During deposition of the Yingcheng Formation, the climate was south Asian tropical. Vegetation consisted mainly of coniferous forest and herbal shrub. In addition, fresh and saline non-marine water dominated the lacustrine setting during deposition of these formations. Deposition of the Denglouku Formation, however, occurred under a hot and dry tropical climate. The vegetation was mostly coniferous forest and lake waters became saline. Palaeoclimate variation is correlated by the lake level change and the development of sedimentary facies. Palaeoclimate contribute to the formation of hydrocarbon source rocks and reservoir.

  2. Alternative marine and fluvial models for the non-fossiliferous quartzitic sandstones of the Early Proterozoic Daspoort Formation, Transvaal Sequence of southern Africa

    Science.gov (United States)

    Eriksson, P. G.; Schreiber, U. M.; van der Neut, M.; Labuschagne, H.; Van Der Schyff, W.; Potgieter, G.

    1993-04-01

    This paper discusses some of the problems related to the palaeoenvironmental interpretation of non-fossiliferous, early Precambrian, recrystallised quartzitic sandstones, using the Early Proterozoic Daspoort Formation, Transvaal Sequence of southern Africa as a case study. These cross-bedded and planar stratified rocks have been interpreted previously as shallow marine deposits, based on limited studies of areas with well-exposed, relatively undeformed outcrops. This postulate rests largely on the apparently mature nature of the recrystallised sandstones and their thin bedding. Examination of outcrops throughout the preserved basin, including those which have been deformed and metamorphosed, reveals the presence of subordinate immature sandstones. Lateral facies relationships permit an alternative distal fan-fluvial braidplain model to be proposed. This is compatible with collected palaeocurrent data, thicknes trends and results of thin section petrography.

  3. Geochemical evidence for subduction in the early Archaean from quartz-carbonate-fuchsite mineralization, Isua Supracrustal Belt, West Greenland

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Rosing, Minik Thorleif; Bird, Dennis K.

    Quartz, carbonate and fuchsite (chromian muscovite) is a common metasomatic assemblage observed in orogenic gold systems, both in Phanerozoic convergent margin settings, and within supracrustal and greenstone belts of Precambrian rocks. Geologic and geochemical observations in younger orogenic...... systems suggest that ore-forming metasomatic fluids are derived from subduction-related devolitilization reactions, implying that orogenic Au-deposits in Archaean and Proterozoic supracrustal rock suites are related to subduction-style plate tectonics beginning early in Earth history. Justification...... with Phanerozoic orogenic deposits and that this type of metasomatism is a unique result of subduction-related processes. Fuchsite from the ISB has a δ18O and δD of 7.7 to 17.9‰ and -115 to -61‰, respectively. δ18O of quartz from the same rocks is between 10.3 and 18.6‰. Muscovite-quartz oxygen isotope thermometry...

  4. Detrital zircon ages in Buller and Takaka terranes, New Zealand : constraints on early Zealandia history

    International Nuclear Information System (INIS)

    Adams, C.J.; Mortimer, N.; Campbell, H.J.; Griffin, W.L.

    2015-01-01

    Detrital zircon ages are presented for 34 early Palaeozoic sandstones from Buller and Takaka terranes, New Zealand, and formerly adjacent parts of Australia-Antarctica. The Buller-Takaka datasets always have two major groups: Ordovician-late Neoproterozoic, 444-700 Ma (but mainly 540-700 Ma), termed 'Gondwana Assembly' (GA), and early Neoproterozoic-Mesoproterozoic, 700-1600 Ma (but mainly 900-1200 Ma), termed 'Rodinia Assembly' (RA). In both terranes, significant age components within these groups are strikingly similar and also have RA/GA ratios, 0.6-1.8. The Cambrian volcanic arc of the Takaka Terrane has contributed little to the zircon patterns. Proportions of Late Cambrian-Early Ordovician zircons, characteristic of granitoid sources in the Ross-Delamerian Orogen are low. The zircons are predominantly reworked with contemporary zircons only evident in a few Buller datasets. The zircon patterns suggest that two major sources (late Mesoproterozoic and late Neoproterozoic), enduring over 120 Ma, were widely distributed and it is postulated they form Precambrian basement beneath southern Zealandia. (author).

  5. Diversity dynamics of silurian-early carboniferous land plants in South china.

    Directory of Open Access Journals (Sweden)

    Conghui Xiong

    Full Text Available New megafossil and microfossil data indicate four episodes in the diversification of Silurian-Early Carboniferous land plants of South China, a relatively continuous regional record. Plant diversity increased throughout, but the rising curve was punctuated by three major falls. There were peaks of origination in the Ludlow-Pragian, Givetian, late Famennian and Visean and peaks of extinction in the Pragian-Emsian, Givetian and early Tournaisian. Speciation and extinction rates were highest in the Lochkovian-Pragian and became progressively lower in subsequent stages. High correlation coefficients indicate that these events are associated with the availability of land habitat contingent on eustatic variations and increasing numbers of cosmopolitan genera. Meanwhile, proportions of endemic genera declined gradually. Due to less endemism and more migrations, both speciation and species extinction rates reduced. The changes of diversity and the timing of the three extinctions of land plants in South China are similar to those known already from Laurussia. However, the largest events in the Lochkovian-Pragian and subsequent smaller ones have not been seen in the global pattern of plant evolution. These land plant events do not correspond well temporally with those affecting land vertebrates or marine invertebrates. In South China, the diversity curve of land plants is generally opposite to that of marine faunas, showing a strong effect of eustatic variations. The increasing diversity of both land vertebrates and plants was punctuated above the Devonian-Carboniferous boundary, known as Romer's Gap, implying common underlying constraints on macroevolution of land animals and plants.

  6. Geochemistry and Nd-Sr isotopic signatures of the Pensamiento Granitoid Complex, Rondonian-San Ignacio Province, eastern precambrian shield of Bolivia: petrogenetic constraints for a mesoproterozoic magmatic arc setting

    International Nuclear Information System (INIS)

    Matos, Ramiro; Teixeira, Wilson; Bettencourt, Jorge Silva; Geraldes, Mauro Cesar

    2009-01-01

    The Pensamiento Granitoid Complex (PGC), located in the northern part of the eastern Precambrian shield of Bolivia, is tectonically assigned to the Rondonian-San Ignacio Province (1.55 - 1.30 Ga) of the Amazonian Craton that is made up by Archean and Proterozoic provinces. The Proterozoic ones result from accretionary orogens that become successively younger south westwards, such as the Rondonian/San Ignacio (1.37 - 1.32 Ga) and the Sunsas orogenies (1.20 - 1.00 Ga). The PGC crops out mainly on the 'Paragua craton' bounded to the south by the Sunsas belt, and composed of granites and subvolcanic terms, and subordinately of syenites, granodiorites, tonalites, trondhjemites and diorites as orogenic representatives of the Rondonian/San Ignacio Orogeny, intrusive into the Lomas Maneches (ca. 1.68 Ga) and Chiquitania (ca. 1.7 Ga) complexes. Thirteen whole rock chemical analyses for major, trace and REE elements were performed for the La Junta, San Martin, Diamantina, Porvernir, San Cristobal, Piso Firme plutons of the PGC. The negative trends of MgO, Al 2 O 3 and CaO contents with increasing SiO 2 suggest that fractional crystallization played an important role in the petrogenesis of the investigated rocks. The data also indicate a mainly peraluminous, sub-alkaline to high-K calc-alkaline composition, and fractionated LREE/HREE patterns are consistent with a magmatic arc character for these plutons. SHRIMP U-Pb zircon ages of the La Junta and San Martin syn- to late-kinematic plutons are 1347 ± 21 Ma and 1373 ± 20 Ma respectively, and the Sm-Nd T DM model ages are between 1.9 to 2.0 Ga, while ε Nd(1330) values range from +1.8 to -4.3, respectively. In addition, the late- to post-kinematic Diamantina pluton yields SHRIMP U-Pb zircon age of 1340 ± 20 Ma, and variable Sm-Nd T DM model ages (1.6 to 1.9 Ga) and ε Nd(1330) values (+0.4 to -1.2) that are comparable with previous results found for other coeval plutons. The Porvenir, San Cristobal and Piso Firme plutons

  7. Chapter G: Tentative Correlation Between CIPW Normin pl (Total Plagioclase) and Los Angeles Wear in Precambrian Midcontinental Granites-Examples from Missouri and Oklahoma, with Applications and Limitations for Use

    Science.gov (United States)

    Davis, George H.

    2004-01-01

    The normative chemical classification of Cross, Iddings, Pirsson, and Washington (CIPW) is commonly used in igneous petrology to distinguish igneous rocks by comparing their magmatic chemistries for similar and dissimilar components. A potential use for this classification other than in petrologic studies is in the rapid assessment of aggregate sources, possibly leading to an economic advantage for an aggregate producer or user, by providing the opportunity to determine whether further physical testing of an aggregate is warranted before its use in asphalt or concrete pavement. However, the CIPW classification currently should not be substituted for the physical testing required in specifications by State departments of transportation. Demands for physical testing of aggregates have increased nationally as users seek to maximize the quality of the aggregate they purchase for their pavements. Concrete pavements are being laid with increased thicknesses to withstand increasing highway loads. New pavement mixes, most notably Superior Performance Asphalt Pavement ('Superpave'), are designed for additional service life. For both concrete and asphalt, the intent is to generate a durable pavement with a longer service life that should decrease overall life-cycle costs. Numerous aggregate producers possess chemical-composition data available for examination to answer questions from the potential user. State geological surveys also possess chemical-composition data for stone sources. Paired with the results of physical testing, chemical- composition data provide indicative information about stone durability and aggregate strength. The Missouri Department of Transportation has noted a possible relation among coarse-grained Precambrian granites of the midcontinental region, correlating the results of abrasion testing with the contents of normative minerals, also known as normins, calculated from chemical composition data. Thus, normin pl ( total plagioclase) can predict, by

  8. Deep questions about the nature of early-life signals: a commentary on Lister (1673) ‘A description of certain stones figured like plants’

    Science.gov (United States)

    Brasier, Martin

    2015-01-01

    In 1673, Martin Lister explored the preservation of ‘St Cuthbert's beads’ plus other fossil crinoid remains from approximately 350 Ma Carboniferous limestone in northern England. He used taphonomic evidence (transport, disarticulation, burial and cementation) to infer an origin as petrified plant remains, in contrast with his views expressed elsewhere that fossil mollusc shells could have formed abiogenically, by ‘plastic forces’ within rock. Lister also observed pentagonal symmetry, now seen as characteristic of living echinoderm skeletons. A postscript from John Ray supports Lister's ‘taphonomic’ observations and accepts the biogenicity of these fossil ‘vegetables’. Ray then concluded with a prophecy, predicting the discovery of comparable living fossils in remote ocean waters. These early discussions compare with current debates about the character of candidate microfossils from the early Earth and Mars. Interesting biomorphs are now tested against the abiogenic null hypotheses, making use of features such as those pioneered by Lister, including evidence for geological context, rules for growth and taphonomy. Advanced techniques now allow us to extend this list of criteria to include the nanoscale mapping of biology-like behaviour patterns plus metabolic pathways. Whereas the science of palaeobiology once began with tests for biogenicity, the same is now true for geobiology and astrobiology. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society. PMID:25750150

  9. Precambrian Surface Temperatures and Molecular Phylogeny

    Science.gov (United States)

    Schwartzman, David; Lineweaver, Charles H.

    2004-06-01

    The timing of emergence of major organismal groups is consistent with the climatic temperature being equal to their upper temperature limit of growth (T_{max}), implying a temperature constraint on the evolution of each group, with the climatic temperature inferred from the oxygen isotope record of marine cherts. Support for this constraint comes from the correlation of T_{max} with the rRNA molecular phylogenetic distance from the last common ancestor (LCA) for both thermophilic Archaea and Bacteria. In particular, this correlation for hyperthermophilic Archaea suggests a climatic temperature of about 120°C at the time of the LCA, likely in the Hadean.

  10. Early or Premature Menopause

    Science.gov (United States)

    ... email updates Enter email Submit Early or premature menopause Menopause that happens before age 40 is called ... What is the difference between early and premature menopause? Early or premature menopause happens when ovaries stop ...

  11. Occurrence of helically coiled microfossil Obruchevella in the Owk ...

    Indian Academy of Sciences (India)

    In the Owk Shale, four species of Obruchevella, viz., O. delicata, O. parva, O. minor and O. .... Asterisk indicate the level of the occurrence of carbonaceous fossils. (c) Locality ...... A B (Moscow: Nauka), English translation published in. 1990 ...

  12. Microfossils in surface sediments of brackish waters on the west ...

    African Journals Online (AJOL)

    A faunistic survey covering 25 sites in estuaries, coastal lakes and ponds along the west coast of South Africa between the Cape of Good Hope in the south and the Olifants River in the north was carried out in May 2014. The study aimed to establish a dataset with ecological and distribution data of ostracods and ...

  13. Microfacies and microfossils in Upper Jurassic limestones from Cheile Turenilor

    Directory of Open Access Journals (Sweden)

    Emanoil Săsăran

    2001-09-01

    Full Text Available In the Cheile Turenilor (Tureni Gorges area, a carbonate succession about 150 m thick developed on top of island arc magmatites. It mainly consist of gravity - induced deposits (debris flows, mass flows and grain flows. Coral, sponges and stromatoporoid bioconstructions are associated. Microbolites play an important role, as binders of the intraclastic rudstones/ grainstones facies, as well as of the incorporated corals, sponges, stromatoporoids, bryozoans, molluscs.

  14. Early hospital discharge and early puerperal complications.

    Science.gov (United States)

    Ramírez-Villalobos, Dolores; Hernández-Garduño, Adolfo; Salinas, Aarón; González, Dolores; Walker, Dilys; Rojo-Herrera, Guadalupe; Hernández-Prado, Bernardo

    2009-01-01

    To evaluate the association between time of postpartum discharge and symptoms indicative of complications during the first postpartum week. Women with vaginal delivery at a Mexico City public hospital, without complications before the hospital discharge, were interviewed seven days after delivery. Time of postpartum discharge was classified as early (25 hours). The dependent variable was defined as the occurrence and severity of puerperal complication symptoms. Out of 303 women, 208 (68%) were discharged early. However, women with early discharge and satisfactory prenatal care had lower odds of presenting symptoms in early puerperium than women without early discharge and inadequate prenatal care (OR 0.36; 95% confidence intervals = 0.17-0.76). There was no association between early discharge and symptoms of complications during the first postpartum week; the odds of complications were lower for mothers with early discharge and satisfactory prenatal care.

  15. Late Archaean-early Proterozoic source ages of zircons in rocks from the Paleozoic orogen of western Galicia, NW Spain

    Energy Technology Data Exchange (ETDEWEB)

    Kuijper, R P; Priem, H N.A. [Laboratorium voor Isotopen-Geologie, Amsterdam (Netherlands); Den Tex, E [Rijksuniversiteit Utrecht (Netherlands). Inst. voor Aardwetenschappen

    1982-08-01

    U-Pb data are reported for nine suites of zircons and three monazites from the Paleozoic orogen in western Galicia: one paragneiss and six orthogneisses from the early Paleozoic basement, and two Carboniferous (ca. 310 Ma old) intrusions of two-mica granite. New whole-rock Rb-Sr analyses, along with earlier data, indicate an age of ca. 470-440 Ma (Ordovician) for the emplacement of the granitic precursors of the orthogneisses. Monazite from the paragneiss also yields an U-Pb age of ca. 470 Ma. From the high initial /sup 87/Sr//sup 86/Sr ratios an involvement of Precambrian continental crust material is evident in the generation of the early Paleozoic suite of granites, while the zircon U-Pb data give evidence of the presence of about 3.0-2.0 Ga old (late Archaean-early Proterozoic) components in the source material. Zircons from the oldest sedimentary rocks in the area, now present as catazonal paragneisses and a likely source for the granites, likewise reveal a provenance age of 3.0-2.0 Ga.

  16. Early Childhood Systems: Transforming Early Learning

    Science.gov (United States)

    Kagan, Sharon Lynn, Ed.; Kauertz, Kristie, Ed.

    2012-01-01

    In this seminal volume, leading authorities strategize about how to create early childhood systems that transcend politics and economics to serve the needs of all young children. The authors offer different interpretations of the nature of early childhood systems, discuss the elements necessary to support their development, and examine how…

  17. Early discharge following birth

    DEFF Research Database (Denmark)

    Nilsson, Ingrid M. S.; Kronborg, Hanne; Knight, Christopher H.

    2017-01-01

    .26–0.48) and primiparous compared to multiparous had an OR of 0.22 (CI 0.17–0.29) for early discharge. Other predictors for early discharge were: no induction of labour, no epidural painkiller, bleeding less than 500 ml during delivery, higher gestational age, early expected discharge and positive breastfeeding experience...

  18. Early Palaeogene planktic foraminiferal and carbon isotope stratigraphy, ODP hole 762C, Exmouth plateau, Northwest Australian margin

    International Nuclear Information System (INIS)

    Hancock, H.J.L.; Dickens, G.R.; Henderson, R.R.; Chaproniere, G.C.

    1999-01-01

    Full text: Although the North West Shelf of Australia is an important region for petroleum exploration and palaeoceanographic investigations the stratigraphy for the Palaeogene is poorly documented, especially for foraminifera. Ocean Drilling Program (ODP) Site 762 on the Exmouth Plateau contains an expanded Palaeogene sequence with abundant, calcareous microfossils. Early Palaeogene cores from this location were examined in this study for their planktic foraminiferal assemblages and carbon isotope compositions (Subbotina spp.). The sequence from 502.96 to 307.8 mbsf was deposited between the early Paleocene and Middle Eocene, and contains all planktic foraminiferal Zones Plc through P10 of the current global scheme, except Subzone P4b. Planktic foraminifera are generally very well preserved and 75 species belonging to 17 genera were identified. Despite a relatively high latitude Palaeogene location for Site 762, planktic foraminiferal biozones are generally in phase with those of the currently used global scheme for subtropical locations (Berggren et al., 1995). However, rare, patchy or non-occurrences of the zonal marker species Globanomalina pseudomenardii, Morozovella velascoensis, M formosa, Planorotalites palmerae and Hanfkenina nuttalli, make some correlations difficult. Planktic foraminiferal assemblages show three increasing diversity trends: at the P3a P3b boundary with the first appearance of muricate Acarinina species; in the middle of P4a b with the first appearances of many warm water Morozovella and Acarinina species and at the P8/P9 zonal boundary with the arrival of late early Eocene Acarinina species. Overall, trends in 13 C of planktic foraminifera are similar in shape to global isotope curves spanning the early Palaeogene, although the prominent short term negative excursion across the latest Paleocene thermal maximum (LPTM) is partly missing, probably because of a gap in core recovery. Combined with nannofossil biostratigraphy and a

  19. Early and late cretaceous magmatism from Sao Sebastiao island (SE-Brazil): geochemistry and petrology

    International Nuclear Information System (INIS)

    Bellieni, G.; Cavazzini, G.; Montes-Lauar, C.R.; Melfi, A.J.; Pacca, I.G.; De Min, A.; Piccirillo, E.M.

    1990-01-01

    The Sao Sebastiao island (236 km 2 ), located along the coast of the Sao Paulo State (Southern Brazil), is characterized by precambrian granitic affected by the Brasiliano tectonic-metamorphic cycle. This crystalline basement is intruded by Early Cretaceous (EC) sub alkaline basic and acid dykes, as well as by Late Cretaceous (LC) alkaline stocks (syenites) and dykes (basanite to phonolite). Geochemical, Sr-isotopic and mineral chemistry data point out that: EC-dykes reveal a basic-acid bimodal character, similar to that of the 'coeval' Parana basin flood volcanics; the acid dykes correspond, in composition, to the acid volcanics of the northern Parana basin: the EC-dykes can represent the eastern extension of the inland Santos-Rio de Janeiro dyke swarm, and LC alkaline stocks and dykes constitute distinct groups, characterized by different Sr-isotope initial ratios (syenites: av. 0.7052 and basanites + tephrites = av. 0.7045), which indicate that they are related to different time-integrated mantle source materials. (author)

  20. Chuaria circularis from the early Mesoproterozoic Suket Shale ...

    Indian Academy of Sciences (India)

    The origin and nature of Chuaria circularis has long been a topic of debate in Precambrian paleo- ... inorganic remains in various studies (see Hofmann. 1992). Ford and Breed (1973) concluded that. Chuaria was a plant, ..... and may be diagnostic criterion and argued that the marginal flange described by Ford and Breed.

  1. Early Transcendental Analysis

    OpenAIRE

    Cowell, Simon; Poulin, Philippe

    2015-01-01

    In Early Transcendentals (The American Mathematical Monthly, Vol. 104, No 7) Steven Weintraub presents a rigorous justifcation of the "early transcendental" calculus textbook approach to the exponential and logarithmic functions. However, he uses tools such as term-by-term differentiation of infinite series. We present a rigorous treatment of the early transcendental approach suitable for a first course in analysis, using mainly the supremum property of the real numbers.

  2. Paleogeographic significance of Clavohamulus hintzei Miller (Conodonta) and other Ibexian conodonts in an early Paleozoic carbonate platform facies of the Argentine Precordillera

    Science.gov (United States)

    Lehnert, O.; Miller, J.F.; Repetski, J.E.

    1997-01-01

    Pre-Tremadocian conodonts and trilobites and Tremadocian conodonts are reported from the Cambrian and Ordovician La Silla Formation in the Cerro La Silla section in east-southeast Ja??chal, San Juan Province, Argentina. A shallow marine conodont fauna contains elements of Clavohamulus hintzei Miller, a common species in North America, but reported for the first time from the early Paleozoic platform carbonates of the western Argentine Precordillera. The presence of this species suggests a correlation with the Clavohamulus hintzei conodont subbiozone of the Cordylodus intermedius conodont biozone in North America, considered Early Ordovician (Skullrockian Stage, Ibexian Series) in North America, but by South American and European standards, this biozone would be of latest Cambrian age. C. hintzei and associated conodonts of the La Silla Formation are typical of the tropical faunas of the North American Midcontinent Faunal Province; Late Cambrian trilobites from lower in the formation also are typical North American taxa. The presence of these faunas in the platform carbonates is consistent with plate reconstructions suggesting that the Precordillera was in a tropical or subtropical position close to Laurentia during the late Precambrian and early Paleozoic. These new paleontological data provide one more argument for recent models of the Precordillera as a displaced terrane derived from the Ouachita Embayment at the southern margin of Laurentia.

  3. Early Retirement Payoff

    Science.gov (United States)

    Fitzpatrick, Maria D.; Lovenheim, Michael F.

    2014-01-01

    As public budgets have grown tighter over the past decade, states and school districts have sought ways to control the growth of spending. One increasingly common strategy employed to rein in costs is to offer experienced teachers with high salaries financial incentives to retire early. Although early retirement incentive (ERI) programs have been…

  4. Early Modern Philosophical Systems

    NARCIS (Netherlands)

    L. van Bunge (Wiep)

    2014-01-01

    textabstractThe occurrence of an entry on early modern philosophical systems in an encyclopaedia of Neo-Latin studies is fraught with complications, if only on account of the gradual disappearance during the early modern period of Latin as the main vehicle of philosophical communication. What

  5. Early Intervention in Budapest.

    Science.gov (United States)

    Gallai, Maria; Katona, Ferenc; Balogh, Erzsebet; Schultheisz, Judit; Deveny, Anna; Borbely, Sjoukje

    2000-01-01

    This article presents five models of early intervention used in Budapest. Diagnostic and treatment methods used by the Pediatric Institute and the Conductive Education System are described, along with the Deveny Special Manual Technique and Gymnastic Method, the Gezenguz method and techniques used in the Early Developmental Center. (CR)

  6. The early universe

    International Nuclear Information System (INIS)

    Steigman, G.

    1989-01-01

    The author discusses the physics of the early universe: the production and survival of relics from the big bang. The author comments on relic WIMPs as the dark matter in the universe. The remainder of this discussion is devoted to a review of the status of the only predictions from the early evolution of the universe that are accessible to astronomical observation: primordial nucleosynthesis

  7. Early College High Schools

    Science.gov (United States)

    Dessoff, Alan

    2011-01-01

    For at-risk students who stand little chance of going to college, or even finishing high school, a growing number of districts have found a solution: Give them an early start in college while they still are in high school. The early college high school (ECHS) movement that began with funding from the Bill and Melinda Gates Foundation 10 years ago…

  8. Early Option Exercise

    DEFF Research Database (Denmark)

    Heje Pedersen, Lasse; Jensen, Mads Vestergaard

    A classic result by Merton (1973) is that, except just before expiration or dividend payments, one should never exercise a call option and never convert a convertible bond. We show theoretically that this result is overturned when investors face frictions. Early option exercise can be optimal when...... it reduces short-sale costs, transaction costs, or funding costs. We provide consistent empirical evidence, documenting billions of dollars of early exercise for options and convertible bonds using unique data on actual exercise decisions and frictions. Our model can explain as much as 98% of early exercises...

  9. Early Option Exercise

    DEFF Research Database (Denmark)

    Jensen, Mads Vestergaard; Heje Pedersen, Lasse

    2016-01-01

    A classic result by Merton (1973) is that, except just before expiration or dividend payments, one should never exercise a call option and never convert a convertible bond. We show theoretically that this result is overturned when investors face frictions. Early option exercise can be optimal when...... it reduces short-sale costs, transaction costs, or funding costs. We provide consistent empirical evidence, documenting billions of dollars of early exercise for options and convertible bonds using unique data on actual exercise decisions and frictions. Our model can explain as much as 98% of early exercises...

  10. Early detection of psychosis

    DEFF Research Database (Denmark)

    Larsen, Tor Ketil; Melle, Ingrid; Auestad, B.

    2011-01-01

    Background During the last decades we have seen a new focus on early treatment of psychosis. Several reviews have shown that duration of untreated psychosis (DUP) is correlated to better outcome. However, it is still unknown whether early treatment will lead to a better long-term outcome....... This study reports the effects of reducing DUP on 5-year course and outcome. Method During 1997–2000 a total of 281 consecutive patients aged >17 years with first episode non-affective psychosis were recruited, of which 192 participated in the 5-year follow-up. A comprehensive early detection (ED) programme...... and cognitive factors and for global assessment of functioning for social functioning at 5-year follow-up. The ED group also had more contacts with friends. Regression analysis did not find that these differences could be explained by confounders. Conclusions Early treatment had positive effects on clinical...

  11. Early Head Start Evaluation

    Data.gov (United States)

    U.S. Department of Health & Human Services — Longitudinal information from an evaluation where children were randomly assigned to Early Head Start or community services as usual;direct assessments and...

  12. Guideline for Early Interventions

    National Research Council Canada - National Science Library

    Vries, de, Maaike

    2006-01-01

    .... During the last years, the demand for early interventions has been increasing. International literature has shown that the psychosocial effects of disaster and military deployment may last for years...

  13. Early Life Stages

    Science.gov (United States)

    Childhood should be viewed as a sequence of lifestages, from birth through infancy and adolescence. When assessing early life risks, consideration is given to risks resulting from fetal exposure via the pregnant mother, as well as postnatal exposures.

  14. Cancer treatment - early menopause

    Science.gov (United States)

    Premature menopause; Ovarian insufficiency - cancer ... Cancer treatments that can cause early menopause include: Surgery. Having both ovaries removed causes menopause to happen right away. If you are age 50 or younger, your provider may ...

  15. Early intervention in psychosis

    DEFF Research Database (Denmark)

    Csillag, Claudio; Nordentoft, Merete; Mizuno, Masafumi

    2017-01-01

    AIM: Early intervention in psychosis (EIP) is a well-established approach with the intention of early detection and treatment of psychotic disorders. Its clinical and economic benefits are well documented. This paper presents basic aspects of EIP services, discusses challenges to their implementa......AIM: Early intervention in psychosis (EIP) is a well-established approach with the intention of early detection and treatment of psychotic disorders. Its clinical and economic benefits are well documented. This paper presents basic aspects of EIP services, discusses challenges...... benefits alone is not enough to promote implementation, as economic arguments and political and social pressure have shown to be important elements in efforts to achieve implementation. CONCLUSIONS: Users' narratives, close collaboration with community organizations and support from policy-makers and known...

  16. Earth's early biosphere

    Science.gov (United States)

    Des Marais, D. J.

    1998-01-01

    Understanding our own early biosphere is essential to our search for life elsewhere, because life arose on Earth very early and rocky planets shared similar early histories. The biosphere arose before 3.8 Ga ago, was exclusively unicellular and was dominated by hyperthermophiles that utilized chemical sources of energy and employed a range of metabolic pathways for CO2 assimilation. Photosynthesis also arose very early. Oxygenic photosynthesis arose later but still prior to 2.7 Ga. The transition toward the modern global environment was paced by a decline in volcanic and hydrothermal activity. These developments allowed atmospheric O2 levels to increase. The O2 increase created new niches for aerobic life, most notably the more advanced Eukarya that eventually spawned the megascopic fauna and flora of our modern biosphere.

  17. Mercury's Early Geologic History

    Science.gov (United States)

    Denevi, B. W.; Ernst, C. M.; Klima, R. L.; Robinson, M. S.

    2018-05-01

    A combination of geologic mapping, compositional information, and geochemical models are providing a better understanding of Mercury's early geologic history, and allow us to place it in the context of the Moon and the terrestrial planets.

  18. Embracing early literacy indicators

    DEFF Research Database (Denmark)

    Broström, Stig; Hansen, Ole Henrik; Jensen, Anders Skriver

    2010-01-01

    Abstract til paper om early literacy indikatorer. Det paper abstractet er knyttet til var en del af et inviteret, selvorganiseret symposium som afrapporterede EASE-projektet (www.ease-eu.com) på OMEP's 26. verdenskongres.......Abstract til paper om early literacy indikatorer. Det paper abstractet er knyttet til var en del af et inviteret, selvorganiseret symposium som afrapporterede EASE-projektet (www.ease-eu.com) på OMEP's 26. verdenskongres....

  19. Who Gets Early Tracheostomy?

    Science.gov (United States)

    Shaw, Joshua J.

    2015-01-01

    BACKGROUND: Although the benefits of early tracheostomy in patients dependent on ventilators are well established, the reasons for variation in time from intubation to tracheostomy remain unclear. We identified clinical and demographic disparities in time to tracheostomy. METHODS: We performed a level 3 retrospective prognostic study by querying the University HealthSystem Consortium (2007-2010) for adult patients receiving a tracheostomy after initial intubation. Time to tracheostomy was designated early ( 10 days). Cohorts were stratified by time to tracheostomy and compared using univariate tests of association and multivariable adjusted models. RESULTS: A total of 49,191 patients underwent tracheostomy after initial intubation: 42% early (n = 21,029) and 58% late (n = 28,162). On both univariate and multivariable analyses, women, blacks, Hispanics, and patients receiving Medicaid were less likely to receive an early tracheostomy. Patients in the early group also experienced lower rates of mortality (OR, 0.84; 95% CI, 0.79-0.88). CONCLUSIONS: Early tracheostomy was associated with increased survival. Yet, there were still significant disparities in time to tracheostomy according to sex, race, and type of insurance. Application of evidence-based algorithms for tracheostomy may reduce unequal treatment and improve overall mortality rates. Additional research into this apparent bias in referral/rendering of tracheostomy is needed. PMID:26313324

  20. Early Jurassic extensional inheritance in the Lurestan region of the Zagros fold-and-thrust belt, Iran.

    Science.gov (United States)

    Tavani, Stefano; Parente, Mariano; Vitale, Stefano; Puzone, Francesco; Erba, Elisabetta; Bottini, Cinzia; Morsalnejad, Davoud; Mazzoli, Stefano

    2017-04-01

    It has long been recognized that the tectonic architecture of the Zagros mountain belt was strongly controlled by inherited structures previously formed within the Arabian plate. These preexisting features span in age from the pre-Cambrian to the Mesozoic, showing different trends and deformation styles. Yet, these structures are currently not fully understood. This uncertainty is partly related with the paucity of exposures, which rarely allows a direct observation of these important deformation features. The Lurestan Province of Iran provides a remarkable exception, since it is one of the few places of the Zagros mountain belt where exposures of Triassic and Jurassic rocks are widespread. In this area we carried out structural observations on Mesozoic extensional structures developed at the southern margin of the Neo-Tethyan basin. Syn-sedimentary extensional faults are hosted within the Triassic-Cretaceous succession, being particularly abundant in the Jurassic portion of the stratigraphy. Early to Middle Jurassic syn-sedimentary faults are observed in different paleogeographic domains of the area, and their occurrence is coherent with the subsequent transition from shallow-water to deep-sea basin environments, observed in a wide portion of the area. Most of the thrusts exposed in the area may indeed be interpreted as reactivated Jurassic extensional faults, or as reverse faults whose nucleation was controlled by the location of preexisting normal faults, as a result of positive inversion during crustal shortening and mountain building.

  1. The effects of heavy meteorite bombardment on the early evolution — The emergence of the three Domains of life

    Science.gov (United States)

    Gogarten-Boekels, Maria; Hilario, Elena; Gogarten, J. Peter

    1995-06-01

    A characteristic of many molecular phylogenies is that the three domains of life (Bacteria, Archaea, Eucarya) are clearly separated from each other. The analyses of ancient duplicated genes suggest that the last common ancestor of all presently known life forms already had been a sophisticated cellular prokaryote. These findings are in conflict with theories that have been proposed to explain the absence of deep branching lineages. In this paper we propose an alternative scenario, namely, a large meteorite impact that wiped out almost all life forms present on the early Earth. Following this nearly complete frustation of life on Earth, two surviving extreme thermophilic species gave rise to the now existing major groups of living organisms, the Bacteria and Archaea. [The latter also contributed the major portion to the nucleo-cytoplasmic component of the Eucarya]. An exact calibration of the molecular record with regard to time is not yet possible. The emergence of Eucarya in fossil and molecular records suggests that the proposed late impact should have occurred before 2100 million years before present (BP). If the 3500 million year old microfossils [Schopf, J. W. 1993: Science 260: 640 646] are interpreted as representatives of present day existing groups of bacteria (i.e., as cyanobacteria), then the impact is dated to around 3700 million years BP. The analysis of molecular sequences suggests that the separation between the Eucarya and the two prokaryotic domains is less deep then the separation between Bacteria and Archaea. The fundamental cell biological differences between Archaea and Eucarya were obtained over a comparatively short evolutionary distance (as measured in number of substitution events in biological macromolecules). Our interpretation of the molecular record suggests that life emerged early in Earth's history even before the time of the heavy bombardment was over. Early life forms already had colonized extreme habitats which allowed at least two

  2. Redefining early gastric cancer.

    Science.gov (United States)

    Barreto, Savio G; Windsor, John A

    2016-01-01

    The problem is that current definitions of early gastric cancer allow the inclusion of regional lymph node metastases. The increasing use of endoscopic submucosal dissection to treat early gastric cancer is a concern because regional lymph nodes are not addressed. The aim of the study was thus to critically evaluate current evidence with regard to tumour-specific factors associated with lymph node metastases in "early gastric cancer" to develop a more precise definition and improve clinical management. A systematic and comprehensive search of major reference databases (MEDLINE, EMBASE, PubMed and the Cochrane Library) was undertaken using a combination of text words "early gastric cancer", "lymph node metastasis", "factors", "endoscopy", "surgery", "lymphadenectomy" "mucosa", "submucosa", "lymphovascular invasion", "differentiated", "undifferentiated" and "ulcer". All available publications that described tumour-related factors associated with lymph node metastases in early gastric cancer were included. The initial search yielded 1494 studies, of which 42 studies were included in the final analysis. Over time, the definition of early gastric cancer has broadened and the indications for endoscopic treatment have widened. The mean frequency of lymph node metastases increased on the basis of depth of infiltration (mucosa 6% vs. submucosa 28%), presence of lymphovascular invasion (absence 9% vs. presence 53%), tumour differentiation (differentiated 13% vs. undifferentiated 34%) and macroscopic type (elevated 13% vs. flat 26%) and tumour diameter (≤2 cm 8% vs. >2 cm 25%). There is a need to re-examine the diagnosis and staging of early gastric cancer to ensure that patients with one or more identifiable risk factor for lymph node metastases are not denied appropriate chemotherapy and surgical resection.

  3. Early Dementia Screening

    Directory of Open Access Journals (Sweden)

    Peter K. Panegyres

    2016-01-01

    Full Text Available As the population of the world increases, there will be larger numbers of people with dementia and an emerging need for prompt diagnosis and treatment. Early dementia screening is the process by which a patient who might be in the prodromal phases of a dementing illness is determined as having, or not having, the hallmarks of a neurodegenerative condition. The concepts of mild cognitive impairment, or mild neurocognitive disorder, are useful in analyzing the patient in the prodromal phase of a dementing disease; however, the transformation to dementia may be as low as 10% per annum. The search for early dementia requires a comprehensive clinical evaluation, cognitive assessment, determination of functional status, corroborative history and imaging (including MRI, FDG-PET and maybe amyloid PET, cerebrospinal fluid (CSF examination assaying Aβ1–42, T-τ and P-τ might also be helpful. Primary care physicians are fundamental in the screening process and are vital in initiating specialist investigation and treatment. Early dementia screening is especially important in an age where there is a search for disease modifying therapies, where there is mounting evidence that treatment, if given early, might influence the natural history—hence the need for cost-effective screening measures for early dementia.

  4. Early cosmology constrained

    Energy Technology Data Exchange (ETDEWEB)

    Verde, Licia; Jimenez, Raul [Institute of Cosmos Sciences, University of Barcelona, IEEC-UB, Martí Franquès, 1, E08028 Barcelona (Spain); Bellini, Emilio [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Pigozzo, Cassio [Instituto de Física, Universidade Federal da Bahia, Salvador, BA (Brazil); Heavens, Alan F., E-mail: liciaverde@icc.ub.edu, E-mail: emilio.bellini@physics.ox.ac.uk, E-mail: cpigozzo@ufba.br, E-mail: a.heavens@imperial.ac.uk, E-mail: raul.jimenez@icc.ub.edu [Imperial Centre for Inference and Cosmology (ICIC), Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2017-04-01

    We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter Ω{sub MR} < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < N {sub eff} < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is r {sub s} = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to r {sub s} = 150 ± 5 Mpc.

  5. Early maize agriculture and interzonal interaction in southern Peru.

    Science.gov (United States)

    Perry, Linda; Sandweiss, Daniel H; Piperno, Dolores R; Rademaker, Kurt; Malpass, Michael A; Umire, Adán; de la Vera, Pablo

    2006-03-02

    Over the past decade, increasing attention to the recovery and identification of plant microfossil remains from archaeological sites located in lowland South America has significantly increased knowledge of pre-Columbian plant domestication and crop plant dispersals in tropical forests and other regions. Along the Andean mountain chain, however, the chronology and trajectory of plant domestication are still poorly understood for both important indigenous staple crops such as the potato (Solanum sp.) and others exogenous to the region, for example, maize (Zea mays). Here we report the analyses of plant microremains from a late preceramic house (3,431 +/- 45 to 3,745 +/- 65 14C bp or approximately 3,600 to 4,000 calibrated years bp) in the highland southern Peruvian site of Waynuna. Our results extend the record of maize by at least a millennium in the southern Andes, show on-site processing of maize into flour, provide direct evidence for the deliberate movement of plant foods by humans from the tropical forest to the highlands, and confirm the potential of plant microfossil analysis in understanding ancient plant use and migration in this region.

  6. Early Islamic Syria

    DEFF Research Database (Denmark)

    Walmsley, Alan

    After more than a century of neglect, a profound revolution is occurring in the way archaeology addresses and interprets developments in the social history of early Islamic Syria-Palestine. This concise book offers an innovative assessment of social and economic developments in Syria-Palestine sh......After more than a century of neglect, a profound revolution is occurring in the way archaeology addresses and interprets developments in the social history of early Islamic Syria-Palestine. This concise book offers an innovative assessment of social and economic developments in Syria......-Palestine shortly before, and in the two centuries after, the Islamic expansion (the later sixth to the early ninth century AD), drawing on a wide range of new evidence from recent archaeological work. Alan Walmsley challenges conventional explanations for social change with the arrival of Islam, arguing...

  7. Early breastfeeding problems

    DEFF Research Database (Denmark)

    Feenstra, Maria Monberg; Kirkeby, Mette Jørgine; Thygesen, Marianne

    2018-01-01

    Objectives Breastfeeding problems are common and associated with early cessation. Stilllength of postpartum hospital stay has been reduced. This leaves new mothers to establish breastfeeding at home with less support from health care professionals. The objective was to explore mothers’ perspectives...... on when breastfeeding problems were the most challenging and prominent early postnatal. The aim was also toidentify possible factors associated with the breastfeeding problems. Methods In a cross-sectional study, a mixed method approach was used to analyse postal survey data from 1437 mothers with full...... term singleton infants. Content analysis was used to analyse mothers’ open text descriptions of their most challenging breastfeeding problem. Multiple logistic regression was used to calculate odds ratios for early breastfeeding problems according to sociodemographic- and psychosocial factors. Results...

  8. Early Intervention in Psychosis

    Science.gov (United States)

    McGorry, Patrick D.

    2015-01-01

    Abstract Early intervention for potentially serious disorder is a fundamental feature of healthcare across the spectrum of physical illness. It has been a major factor in the reductions in morbidity and mortality that have been achieved in some of the non-communicable diseases, notably cancer and cardiovascular disease. Over the past two decades, an international collaborative effort has been mounted to build the evidence and the capacity for early intervention in the psychotic disorders, notably schizophrenia, where for so long deep pessimism had reigned. The origins and rapid development of early intervention in psychosis are described from a personal and Australian perspective. This uniquely evidence-informed, evidence-building and cost-effective reform provides a blueprint and launch pad to radically change the wider landscape of mental health care and dissolve many of the barriers that have constrained progress for so long. PMID:25919380

  9. Early life vaccination

    DEFF Research Database (Denmark)

    Nazerai, Loulieta; Bassi, Maria Rosaria; Uddbäck, Ida Elin Maria

    2016-01-01

    Intracellular pathogens represent a serious threat during early life. Importantly, even though the immune system of newborns may be characterized as developmentally immature, with a propensity to develop Th2 immunity, significant CD8+ T-cell responses may still be elicited in the context of optimal...... the first period of life and provide a pertinent alternative in infant vaccinology. To address this, infant mice were vaccinated with three different adenoviral vectors and the CD8+ T-cell response after early life vaccination was explored. We assessed the frequency, polyfunctionality and in vivo...... cytotoxicity of the elicited memory CD8+ T cells, as well as the potential of these cells to respond to secondary infections and confer protection. We further tested the impact of maternal immunity against our replication-deficient adenoviral vector during early life vaccination. Overall, our results indicate...

  10. Early anaerobic metabolisms

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene; Rosing, Minik T; Bjerrum, Christian

    2006-01-01

    probably driven by the cycling of H2 and Fe2+ through primary production conducted by anoxygenic phototrophs. Interesting and dynamic ecosystems would have also been driven by the microbial cycling of sulphur and nitrogen species, but their activity levels were probably not so great. Despite the diversity......Before the advent of oxygenic photosynthesis, the biosphere was driven by anaerobic metabolisms. We catalogue and quantify the source strengths of the most probable electron donors and electron acceptors that would have been available to fuel early-Earth ecosystems. The most active ecosystems were...... of potential early ecosystems, rates of primary production in the early-Earth anaerobic biosphere were probably well below those rates observed in the marine environment. We shift our attention to the Earth environment at 3.8Gyr ago, where the earliest marine sediments are preserved. We calculate, consistent...

  11. 75 FR 20830 - Early Learning

    Science.gov (United States)

    2010-04-21

    ... DEPARTMENT OF EDUCATION Early Learning AGENCY: Office of the Secretary, Department of Education... meetings and written submissions, is seeking input from State agencies responsible for early learning and... assistance providers, researchers of early learning, stakeholders who work with early learning and...

  12. Cognitive Development in Early Readers.

    Science.gov (United States)

    Briggs, Chari; Elkind, David

    Some studies of early readers are discussed. It is pointed out that study of early readers has relevance for practical and theoretical issues in psychology and education. Of interest in this document are the following questions: (1) Are there any special talents or traits distinguishing early from non-early readers? (2) Do children who read early…

  13. Introduction to "Early psychosis

    DEFF Research Database (Denmark)

    McGorry, Patrick; Nordentoft, Merete; Simonsen, Erik

    2005-01-01

    warrants careful analysis. The Third International Early Psychosis Conference proved to be a watershed and was the largest and most vibrant meeting to that point. This preface aims to set the scene for a selection of contributions, derived from the array of new evidence reported in Copenhagen, and recently...

  14. Early Functional Abilities

    DEFF Research Database (Denmark)

    Lorentzen, Jakob; Poulsen, Ingrid

    2005-01-01

    Early Functional Abilities (EFA), - en skala til evaluering af behandlingsforløb af svært hjerneskadede patienter i forbindelse med tidlig rehabilitering. Formål At monitorere og dokumentere rehabiliteringsforløbet for svært hjerneskadede patienter, hvor funktionsniveauet endnu ikke kan registreres...

  15. Early Islamic Syria

    DEFF Research Database (Denmark)

    Walmsley, Alan George

    This book presents a new interpretation of social and economic developments in Syria-Palestine in the decades before and during the two centuries after the Islamic expansion into the region (roughly the later 6th to the early 9th century AD). Drawing on a wide range of evidence from recent...

  16. Teaching polymorphism early

    DEFF Research Database (Denmark)

    2005-01-01

    Is it possible to teach dynamic polymorphism early? What techniques could facilitate teaching it in Java. This panel will bring together people who have considered this question and attempted to implement it in various ways, some more completely than others. It will also give participants...

  17. Early childhood aggression

    NARCIS (Netherlands)

    Alink, Lenneke Rosalie Agnes

    2006-01-01

    In this thesis the development, stability, and correlates of early childhood aggression were investigated. The normative development was examined in a general population sample using questionnaires completed by the parents of 12-, 24-, and 36-month-old children and again one year later. Results

  18. Characteristics of early psychosis

    NARCIS (Netherlands)

    Schothorst, P.F.; Emck, C.; van Engeland, H.

    2006-01-01

    There is little research on characteristics related to course and prognosis of early-onset psychosis. The present article aims to advance our knowledge of this disorder for the purpose of proper diagnosis and treatment. It focuses on premorbid and prodromal characteristics, treatment history,

  19. Early practice: neurotology.

    Science.gov (United States)

    Breen, Joseph T; Vrabec, Jeffrey T

    2015-04-01

    Besides technical and surgical proficiency, some of the most important skills for a young Neurotologist to refine include communication and critical thinking abilities. This Early Practice article provides perspectives on common challenges and career development from a current Neurotology fellow and his mentor. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Early Building Design

    DEFF Research Database (Denmark)

    Østergård, Torben; Jensen, Rasmus Lund; Maagaard, Steffen

    2017-01-01

    Highlights •Development of a design methodology that can handle the vast design space in early building design. •A global design space is modelled from extensive Monte Carlo simulations. •Sensitivity analysis methods applied to guide decision-makers. •Interactive visualizations help the multi-act...

  1. Early Childhood Trauma

    Science.gov (United States)

    National Child Traumatic Stress Network, 2010

    2010-01-01

    Early childhood trauma generally refers to the traumatic experiences that occur to children aged 0-6. Because infants' and young children's reactions may be different from older children's, and because they may not be able to verbalize their reactions to threatening or dangerous events, many people assume that young age protects children from the…

  2. Microbial Communities: Tracing Growth Processes from Antarctic Lakes to Early Earth to Other Planets

    Science.gov (United States)

    Sumner, D. Y.

    2014-12-01

    Life in the Universe is dominated by microbes: they are numerically the most abundant cells in our bodies and in Earth's biosphere, and they are the only life that might be present elsewhere in our solar system. Life beyond our solar system could include macroscopic organisms, but everything we understand about the origin of life suggests it must start with microbes. Thus, understanding microbial ecosystems, in the absence of macroscopic organisms, is critical to understanding early life on Earth and life elsewhere in the Universe - if it exists. But what are the general principles of microbial ecology in the absence of predation? What happens when each cell is a chemical factory that can swap among metabolic processes in response to environmental and emergent cues? Geobiologists and astrobiologists are addressing these questions in diverse ways using both Earth's modern biosphere and its fossil record. Modern microbial communities in shallow, ice-covered lakes, Antarctica (Fig.), provide a model for high productivity microbial ecosystems with no to low predation. In these lakes, photosynthetic communities create macroscopic pinnacles and domes, sometime lithified into stromatolites. They provide an ecological, geochemical and morphological model for Precambrian microbial communities in low sedimentation, low current environments. Insights from these communities include new growth processes for ancient mats, especially some that grew prior to the oxidation of Earth's atmosphere. The diversity of biosignatures created in these communities also provides context for models of life under ice elsewhere in our solar system such as paleolakes on Mars and on icy moons. Results from the Mars Science Laboratory (MSL) team document formerly habitable fluvial and lacustrine environments. Lacustrine environments, in particular, are favorable for preserving biosignatures, and continued investigations by MSL will provide a deeper understanding of the duration of habitable

  3. Tracing Biosignature Preservation of Geothermally Silicified Microbial Textures into the Geological Record.

    Science.gov (United States)

    Campbell, Kathleen A; Lynne, Bridget Y; Handley, Kim M; Jordan, Sacha; Farmer, Jack D; Guido, Diego M; Foucher, Frédéric; Turner, Susan; Perry, Randall S

    2015-10-01

    New Zealand and Argentine (Late Jurassic-Recent) siliceous hot-spring deposits (sinter) reveal preservation pathways of environmentally controlled, microbe-dominated sedimentary facies over geological time scales. Texturally distinctive, laminated to thinly layered, dense and vertically oriented, microtubular "palisade" fabric is common in low-temperature (geological events. A systematic approach was used to characterize palisade fabric in sinters of different ages to refine tools for recognizing biosignatures in extreme environments and to track their long-term preservation pathways into the geological record. Molecular techniques, scanning electron microscopy, Raman spectrometry, X-ray powder diffraction, petrography, and lipid biomarker analyses were applied. Results indicate that microbial communities vary at the micron scale and that early and rapid silicification is paramount to long-term preservation, especially where minimal postdepositional disturbance follows fossilization. Overall, it appears that the most robust biomarkers of fossil microbial activity in hot-spring deposits are their characteristic macro- and microtextures and laser micro-Raman identified carbon. Studies of Phanerozoic geothermal deposits with mineralized microbial components are relevant analogs for Precambrian geobiology because early life is commonly preserved as microbial microfossils and biofilms in silica, some of it hydrothermal in origin. Yet the diagenetic "movie" has already been run. Hence, studying younger sinters of a range of ages provides an opportunity to "play it again" and follow the varied influences on biosignatures into the deep-time geological record.

  4. Vertebrate assemblages from the early Late Cretaceous of southeastern Morocco: An overview

    Science.gov (United States)

    Cavin, L.; Tong, H.; Boudad, L.; Meister, C.; Piuz, A.; Tabouelle, J.; Aarab, M.; Amiot, R.; Buffetaut, E.; Dyke, G.; Hua, S.; Le Loeuff, J.

    2010-07-01

    OT1 assemblage, possibly corresponds to a specific, localised ecosystem within the Kem Kem beds compound assemblage. Microfossils and facies from the Aoufous Formation, corresponding to the top of the compound assemblage, provide evidence of extremely abiotic conditions (hypersalinity), and thus of great environmental instability. At the base of the Akrabou Formation the first ammonite bioevent, Neolobites, corresponds to the onset of the marine transgression in the early Late Cenomanian while the Agoult assemblage (Late Cenomanian?) contains a variety of small fish species that have Central Tethyan affinities. Finally, the youngest Mammites bioevent in the late Early Turonian corresponds to a deepening of the marine environment: this sequence is isochronous with the Goulmima assemblage, a diverse collection of fish and other marine taxa, and shows affinities with taxa from the South Atlantic, the Central Tethys and the Western Interior seaway of North America, and further highlights the biogeographical importance of these North African Late Cretaceous assemblages.

  5. Early prenatal syphilis

    Directory of Open Access Journals (Sweden)

    Santosh Rathod

    2010-01-01

    Full Text Available Syphilis in pregnancy still remains a challenge despite the availability of adequate diagnostic tests for serological screening and penicillin therapy. We report a case of 2 month old female infant who presented with runny nose, papulosquamous lesions over both palms and soles and perianal erosions since 1 month after birth. Cutaneous examination revealed moist eroded areas in the perianal region and fine scaly lesions over palms and soles. Radiograph of both upper limbs and limbs revealed early periosteal changes in lower end of humerus and lower end of tibia. Diagnosis of early pre-natal syphilis was confirmed by Child′s Serum Rapid Plasma Reagin Antibody test [S.RPR] being positive with 1:64 dilution while that of mother was 1:8.

  6. Early Childhood Caries

    Directory of Open Access Journals (Sweden)

    Yumiko Kawashita

    2011-01-01

    Full Text Available Dental caries is one of the most common childhood diseases, and people continue to be susceptible to it throughout their lives. Although dental caries can be arrested and potentially even reversed in its early stages, it is often not self-limiting and progresses without proper care until the tooth is destroyed. Early childhood caries (ECC is often complicated by inappropriate feeding practices and heavy infection with mutans streptococci. Such children should be targeted with a professional preventive program that includes oral hygiene instructions for mothers or caregivers, along with fluoride and diet counseling. However, these strategies alone are not sufficient to prevent dental caries in high-risk children; prevention of ECC also requires addressing the socioeconomic factors that face many families in which ECC is endemic. The aim of this paper is to systematically review information about ECC and to describe why many children are suffering from dental caries.

  7. Mapping the early Universe

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    From its unique vantage point 900 kilometres above the earth's surface, NASA's Cosmic Background Explorer (COBE) satellite has a privileged view of cosmic background radiation - the remnants of the early (radiation-dominated) Universe which followed the Big Bang some ten Gigayears ago, and possibly some subsequent history. In this way astroparticle physicists get a first peek at the quantum cosmology which moulded the infant Universe

  8. Earthquake Early Warning Systems

    OpenAIRE

    Pei-Yang Lin

    2011-01-01

    Because of Taiwan’s unique geographical environment, earthquake disasters occur frequently in Taiwan. The Central Weather Bureau collated earthquake data from between 1901 and 2006 (Central Weather Bureau, 2007) and found that 97 earthquakes had occurred, of which, 52 resulted in casualties. The 921 Chichi Earthquake had the most profound impact. Because earthquakes have instant destructive power and current scientific technologies cannot provide precise early warnings in advance, earthquake ...

  9. Coaching in Early Mathematics.

    Science.gov (United States)

    Germeroth, Carrie; Sarama, Julie

    2017-01-01

    Falling scores in math have prompted a renewed interest in math instruction at early ages. By their own admission, early childhood educators are generally underprepared and not always comfortable teaching math. Professional development (PD) in early mathematics is widely considered a main way to increase teachers' skills and efficacy (e.g., Guskey, 2000; Hyson & Woods, 2014; Munby, Russell, & Martin, 2001; Piasta, Logan, Pelatti, Capps, & Petrill, 2015; Richardson & Placier, 2001; Sarama, Clements, Wolfe, & Spitler, 2016; Sarama & DiBiase, 2004; Zaslow, 2014). However, it has been documented that stand-alone PD is not as effective in changing practice (e.g., Biancarosa & Bryk, 2011; Garet et al., 2008; Guskey, 2000; Hyson & Woods, 2014; Institute of Medicine and National Research Council, 2015; Joyce & Showers, 2002; Zaslow, 2014). Site-embedded ongoing support in the form of coaching or mentoring has been shown to be critical for successful implementation (Neuman & Cunningham, 2009; Powell, Diamond, Burchinal, & Koehler, 2010). In this chapter, we describe coaching models and abstract characteristics of effective coaching from the research. With this background, we provide an in-depth view of the coaching aspect of two large empirical studies in early mathematics. We introduce the theoretical framework from which the coaching models for these projects were developed and describe the research on which they were based. We then summarize how the planned models were instantiated and challenges to their implementation within each project. In the final section, we summarize what we have learned and described implications and challenges for the field. © 2017 Elsevier Inc. All rights reserved.

  10. Early prevention of obesity

    OpenAIRE

    Claudio Maffeis

    2014-01-01

    Childhood obesity is the metabolic disorder with the highest prevalence in both children and adults. Urgency to treat and prevent childhood obesity is based on the clear evidence that obesity tends to track from childhood to adulthood, is associated to morbidity also in childhood and to long-term mortality. Early life, i.e., intrauterine life and the first two years, is a sensitive window for prevention. Anatomical and functional maturation of the hypothalamic structures devoted to regulating...

  11. Hands of early primates.

    Science.gov (United States)

    Boyer, Doug M; Yapuncich, Gabriel S; Chester, Stephen G B; Bloch, Jonathan I; Godinot, Marc

    2013-12-01

    Questions surrounding the origin and early evolution of primates continue to be the subject of debate. Though anatomy of the skull and inferred dietary shifts are often the focus, detailed studies of postcrania and inferred locomotor capabilities can also provide crucial data that advance understanding of transitions in early primate evolution. In particular, the hand skeleton includes characteristics thought to reflect foraging, locomotion, and posture. Here we review what is known about the early evolution of primate hands from a comparative perspective that incorporates data from the fossil record. Additionally, we provide new comparative data and documentation of skeletal morphology for Paleogene plesiadapiforms, notharctines, cercamoniines, adapines, and omomyiforms. Finally, we discuss implications of these data for understanding locomotor transitions during the origin and early evolutionary history of primates. Known plesiadapiform species cannot be differentiated from extant primates based on either intrinsic hand proportions or hand-to-body size proportions. Nonetheless, the presence of claws and a different metacarpophalangeal [corrected] joint form in plesiadapiforms indicate different grasping mechanics. Notharctines and cercamoniines have intrinsic hand proportions with extremely elongated proximal phalanges and digit rays relative to metacarpals, resembling tarsiers and galagos. But their hand-to-body size proportions are typical of many extant primates (unlike those of tarsiers, and possibly Teilhardina, which have extremely large hands). Non-adapine adapiforms and omomyids exhibit additional carpal features suggesting more limited dorsiflexion, greater ulnar deviation, and a more habitually divergent pollex than observed plesiadapiforms. Together, features differentiating adapiforms and omomyiforms from plesiadapiforms indicate increased reliance on vertical prehensile-clinging and grasp-leaping, possibly in combination with predatory behaviors in

  12. Early Detection Of Cancer

    Directory of Open Access Journals (Sweden)

    V B Bhatnagar

    1987-04-01

    Full Text Available Farly detection of cancer is based upon three fundamental assumptions, firstly that the trea'ment of benign and precancerous lesions reduces the incidence of cancer, secondly, that the treatment of in situ cancers is conducive to total cure and thirdly that early diagnosis and management of invasive cancer ensures be.ter survival. When patient seeks medical advice for vague symptoms, which could however be due to a possible malignant tumour at a particular site, the alert clinician should investigate the patient immediately to exclude cancer. At this stage cancer is usually not significantly advanced. Currently the U. I. C. C. (International Union for Cancer Control} is studying the epidemiology of cancers in various countries The importance of this is two folds : Firstly by focussing attention on a section of population vulnerable to a particular cancer an early detection is facilitated Secondly by changing the causative factors responsible to a particular cancer, the incidence of that cancer can be reduced e. g. reduction in lung cancer following campaigns against ciguette smoking and reductioi in breast cancer after campaigns for advocating breast feeding of infants, lowering fat consumption and encouraging self palpation of breast regularly. Indeed early diagnosis of cancer implies diagnosis of cancer in almost a symptomatic stage It involves motiva’ion of the population towards acquisitio : of knowledge, attitude and practice.. Epidemiologies and clinicians should be able to recognise high risk cases exposed to particular neoplasia and knowledge of alarming symptoms should be pro- pogated for wide publicity through common available media and means. Probable cases should have regular clhrcal examination periodically and relevant investigations including radiological, imaging techniques and Bio-Chemical examination should be undertaken as and when desired Suspicious lesions should be investigated by specific tests including smear cytology

  13. PHOBOS, the Early Years

    Science.gov (United States)

    Stephans, George S. F.; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michalowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A. H.; Wyslouch, B.

    2002-06-01

    The PHOBOS detector, one of the two small experiments at RHIC, focuses on measurements of charged particle multiplicity over almost the full phase space and identified particles near mid-rapidity. Results will be presented from the early RHIC gold--gold runs at nucleon--nucleon center of mass energies of 56 and 130 GeV as well as the recently concluded run at the full RHIC energy of 200 GeV.

  14. Mapping the early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1991-06-15

    From its unique vantage point 900 kilometres above the earth's surface, NASA's Cosmic Background Explorer (COBE) satellite has a privileged view of cosmic background radiation - the remnants of the early (radiation-dominated) Universe which followed the Big Bang some ten Gigayears ago, and possibly some subsequent history. In this way astroparticle physicists get a first peek at the quantum cosmology which moulded the infant Universe.

  15. Early breast cancer

    International Nuclear Information System (INIS)

    Dongen, J.A. van

    1989-01-01

    The therapy of early breast cancer has been changing during the last decennium. It requires a multi-disciplinary approach and in each of these disciplines improvements have been implemented. The result is that treatment schedules can now be adapted to specific subgroups. In this review early breast cancer is defined as operable disease, using the criteria set out by Haagensen. Emphasis is given to describing the new developments in prognostic criteria, since these form the basis for creating subgroups for specific treatment schedules. Distinction is made between the factors relating to growth rate and those relating to metastatic potential. Data on screening promises a beneficial effect of the implementation of screening in national health care programs. Important shifts are seen in treatment schedules; the place of postoperative radiotherapy after classic ablative treatment is being challenged, whereas it plays a major role in the new breast conserving therapy schedules. The data mentioned in the review suggest that a large proportion of 'operable' cases can be treated with breast conservation but details in the technique of breast conserving therapy are still under investigation. They form a major part of the coming prospective studies in breast cancer. Improvements in reconstruction techniques, creating better cosmetic results, make reconstruction more competitive with breast conserving therapy. The use of chemotherapy and endocrine manipulation in early breast cancer has now been clearly confirmed by the overview technique by the Peto-group, thanks to all efforts of individual trialists together. (orig.)

  16. Sedimentary mechanisms of a modern banded iron formation on Milos Island, Greece

    Directory of Open Access Journals (Sweden)

    E. Chi Fru

    2018-05-01

    Full Text Available An early Quaternary shallow submarine hydrothermal iron formation (IF in the Cape Vani sedimentary basin (CVSB on Milos Island, Greece, displays banded rhythmicity similar to Precambrian banded iron formation (BIF. Field-wide stratigraphic and biogeochemical reconstructions show two temporal and spatially isolated iron deposits in the CVSB with distinct sedimentological character. Petrographic screening suggests the presence of a photoferrotrophic-like microfossil-rich IF (MFIF, accumulated on a basement consisting of andesites in a ∼ 150 m wide basin in the SW margin of the basin. A banded nonfossiliferous IF (NFIF sits on top of the Mn-rich sandstones at the transition to the renowned Mn-rich formation, capping the NFIF unit. Geochemical data relate the origin of the NFIF to periodic submarine volcanism and water column oxidation of released Fe(II in conditions predominated by anoxia, similar to the MFIF. Raman spectroscopy pairs hematite-rich grains in the NFIF with relics of a carbonaceous material carrying an average δ13Corg signature of ∼ −25‰. A similar δ13Corg signature in the MFIF could not be directly coupled to hematite by mineralogy. The NFIF, which postdates large-scale Mn deposition in the CVSB, is composed primarily of amorphous Si (opal-SiO2 ⋅ nH2O while crystalline quartz (SiO2 predominates the MFIF. An intricate interaction between tectonic processes, changing redox, biological activity, and abiotic Si precipitation are proposed to have collectively formed the unmetamorphosed BIF-type deposits in a shallow submarine volcanic center. Despite the differences in Precambrian ocean–atmosphere chemistry and the present geologic time, these formation mechanisms coincide with those believed to have formed Algoma-type BIFs proximal to active seafloor volcanic centers.

  17. Early intervention as a catalyst for effective early childhood ...

    African Journals Online (AJOL)

    ... of positive attitudes towards children with disabilities in a country like Ghana. ... As Ghana strides towards mainstreaming early childhood education in the quest ... an integrated, inclusive and effective early intervention programme becomes ...

  18. Les séries du carbonifère inférieur de la région d'Adarouch, NE du Maroc central: lithologie et biostratigraphieEarly carboniferous series of the Adarouch area, northeast central Morocco: lithology and biostratigraphy

    Science.gov (United States)

    Berkhli, M.; Vachard, D.; Paicheler, J.-C.

    2001-05-01

    The early Carboniferous series of the Adarouch area (northeast central Morocco) are subdivided into three sedimentological and biostratigraphical units. The first unit, which belongs to the Late Visean zones V3bβ and V3bγ, was deposited on shallow carbonate platforms. The second unit belongs to the Late Visean zone, V3c, and incudes terrigenous deposits, such as turbidites, shales and olistostromes. The third unit belongs to the Serpukhovian stage and consists of sandstones and limestones. A new biostratigraphical analysis, which is based on foraminiferal, algae and pseudoalgae, allows an accurate dating of the units. The deposits of the zones V3bβ and V3bγ contain characteristic calcareous microfossils, such as Stacheoides sp., Pseudoendothyra sp. and Ungdarella uralica. The V3c zone (300-400 m) is shown in two oolitic beds of the Mouarhaz and Akerchi Formations, respectively, with Janischewskina sp. and Asteroarchaediscus sp. The Serpukhovian stage is characterised by the disappearance of the algae Koninckopora and the appearance of the brachiopod Titanaria. The new data from the Adarouch area confirm the Moroccan biostratigraphical scale of the Moroccan meseta.

  19. Late Cambrian - Early Ordovician turbidites of Gorny Altai (Russia): Compositions, sources, deposition settings, and tectonic implications

    Science.gov (United States)

    Kruk, Nikolai N.; Kuibida, Yana V.; Shokalsky, Sergey P.; Kiselev, Vladimir I.; Gusev, Nikolay I.

    2018-06-01

    The Cambrian-Ordovician transition was the time of several key events in the history of Central Asia. They were the accretion of Mariana-type island arc systems to the Siberian continent, the related large-scale orogeny and intrusions of basaltic and granitic magma and the formation of a huge turbidite basin commensurate with the Bengal Gulf basin in the western part of the Central Asian orogenic belt (CAOB). The structure of the basin, as well as the sources and environments of deposition remain open to discussion. This paper presents new major- and trace-element data on Late-Cambrian-Early Ordovician turbidites from different parts of the Russian Altai and a synthesis of Nd isotope composition and ages of detrital zircons. The turbidites share chemical similarity with material shed from weathered continental arcs. Broad variations of CIA (39-73) and ICV (0.63-1.66) signatures in sandstones suggest origin from diverse sources and absence of significant sorting. Trace elements vary considerably and have generally similar patterns in rocks from different terranes. On the other hand, there are at least two provinces according to Nd isotope composition and age of detrital zircons. Samples from eastern Russian Altai contain only Phanerozoic zircons and have Nd isotope ratios similar to those in Early Cambrian island arcs (εNdt + 4.4… + 5.4; TNd(DM)-2-st = 0.8-0.9 Ga). Samples from central, western, and southern parts of Russian Altai contain Precambrian zircons (some as old as Late Archean) and have a less radiogenic Nd composition (εNdt up to -3.6; TNd(DM)-2-st up to 1.5 Ga). The chemical signatures of Late Cambrian to Early Ordovician turbidites indicate a provenance chemically more mature than the island arc rocks, and the presence of zircons with 510-490 Ma ages disproves their genetic relation with island arcs. The turbidite basin formed simultaneously with peaks of granitic and alkali-basaltic magmatism in the western Central Asian orogen and resulted from

  20. Basement control in the development of the early cretaceous West and Central African rift system

    Science.gov (United States)

    Maurin, Jean-Christophe; Guiraud, René

    1993-12-01

    The structural framework of the Precambrian basement of the West and Central African Rift System (WCARS) is described in order to examine the role of ancient structures in the development of this Early Cretaceous rift system. Basement structures are represented in the region by large Pan-African mobile belts (built at ca. 600 Ma) surrounding the > 2 Ga West African, Congo and Sao Francisco cratons. Except for the small Gao trough (eastern Mali) located near the contact nappe of the Pan-African Iforas suture zone along the edge of the West African craton, the entire WCARS is located within the internal domains of the Pan-African mobile belts. Within these domains, two main structural features occur as the main basement control of the WCARS: (1) an extensive network of near vertical shear zones which trend north-south through the Congo, Brazil, Nigeria, Niger and Algeria, and roughly east-west through northeastern Brazil and Central Africa. The shear zones correspond to intra-continental strike-slip faults which accompanied the oblique collision between the West African, Congo, and Sao Francisco cratons during the Late Proterozoic; (2) a steep metamorphic NW-SE-trending belt which corresponds to a pre-Pan-African (ca. 730 Ma) ophiolitic suture zone along the eastern edge of the Trans-Saharian mobile belt. The post-Pan-African magmatic and tectonic evolution of the basement is also described in order to examine the state of the lithosphere prior to the break-up which occurred in the earliest Cretaceous. After the Pan-African thermo-tectonic event, the basement of the WCARS experienced a long period of intra-plate magmatic activity. This widespread magmatism in part relates to the activity of intra-plate hotspots which have controlled relative uplift, subsidence and occasionally block faulting. During the Paleozoic and the early Mesozoic, this tectonic activity was restricted to west of the Hoggar, west of Aïr and northern Cameroon. During the Late Jurassic-Early

  1. Infusing Early Childhood Mental Health into Early Intervention Services

    Science.gov (United States)

    Grabert, John C.

    2009-01-01

    This article describes the process of enhancing early childhood mental health awareness and skills in non-mental health staff. The author describes a pilot training model, conducted the U.S. Army's Early Intervention Services, that involved: (a) increasing early childhood mental health knowledge through reflective readings, (b) enhancing…

  2. Early Life Exposures and Cancer

    Science.gov (United States)

    Early-life events and exposures have important consequences for cancer development later in life, however, epidemiological studies of early-life factors and cancer development later in life have had significant methodological challenges.

  3. History of early atomic clocks

    International Nuclear Information System (INIS)

    Ramsey, N.F.

    2005-01-01

    This review of the history of early atomic clocks includes early atomic beam magnetic resonance, methods of separated and successive oscillatory fields, microwave absorption, optical pumping and atomic masers. (author)

  4. Early prevention of obesity

    Directory of Open Access Journals (Sweden)

    Claudio Maffeis

    2014-06-01

    Full Text Available Childhood obesity is the metabolic disorder with the highest prevalence in both children and adults. Urgency to treat and prevent childhood obesity is based on the clear evidence that obesity tends to track from childhood to adulthood, is associated to morbidity also in childhood and to long-term mortality. Early life, i.e., intrauterine life and the first two years, is a sensitive window for prevention. Anatomical and functional maturation of the hypothalamic structures devoted to regulating energy intake and expenditure and body size mainly occurs in the first 1,000 days of life. Therefore, factors affecting the foetal exposition to maternal metabolic environment and early postnatal nutrition are crucial in modulating the definition of the metabolic programming processes in the brain. Maternal diseases, mainly malnutrition for defect or excess, obesity and diabetes, placental disorders and dysfunctions, maternal use of alcohol and drugs, smoking, affect long term metabolic programming of the foetus with lifelong consequences. Similarly, early nutrition contributes to complete the long-term metabolic regulating framework initiated in the uterus. Breastfeeding, adequate weaning, attention to portion size and diet composition are potential tools for reducing the obesity risk later in childhood. Longitudinal randomized controlled studies are needed for exploring the efficacy of obesity prevention strategies initiated after conception.Proceedings of the 10th International Workshop on Neonatology · Cagliari (Italy · October 22nd-25th, 2014 · The last ten years, the next ten years in Neonatology Guest Editors: Vassilios Fanos, Michele Mussap, Gavino Faa, Apostolos Papageorgiou

  5. Crowdsourced earthquake early warning

    Science.gov (United States)

    Minson, Sarah E.; Brooks, Benjamin A.; Glennie, Craig L.; Murray, Jessica R.; Langbein, John O.; Owen, Susan E.; Heaton, Thomas H.; Iannucci, Robert A.; Hauser, Darren L.

    2015-01-01

    Earthquake early warning (EEW) can reduce harm to people and infrastructure from earthquakes and tsunamis, but it has not been implemented in most high earthquake-risk regions because of prohibitive cost. Common consumer devices such as smartphones contain low-cost versions of the sensors used in EEW. Although less accurate than scientific-grade instruments, these sensors are globally ubiquitous. Through controlled tests of consumer devices, simulation of an Mw (moment magnitude) 7 earthquake on California’s Hayward fault, and real data from the Mw 9 Tohoku-oki earthquake, we demonstrate that EEW could be achieved via crowdsourcing.

  6. Why Recruits Separate Early

    Science.gov (United States)

    1991-01-01

    our sample were reportedly unable to adjust to the military environment due to social or emotional immaturity. This problem was especially prevalent...Table 9. Table 9 REASONS FOR EARLY SEPARATION 1. Mental health. Phobias , suicide threats and attempts, emotional immaturity, and personality and...hliurfl’lutf t’ htrtiuug tht .’ plinittol piioL’m.9 evIn’ thfll I b’ r i’lli. vre’.Ilv ifao~ , ýI ll.tv ill it](- rv ’: 111nil tln1 (i~..󈧏 4 P A W4.11

  7. Early modern mathematical instruments.

    Science.gov (United States)

    Bennett, Jim

    2011-12-01

    In considering the appropriate use of the terms "science" and "scientific instrument," tracing the history of "mathematical instruments" in the early modern period is offered as an illuminating alternative to the historian's natural instinct to follow the guiding lights of originality and innovation, even if the trail transgresses contemporary boundaries. The mathematical instrument was a well-defined category, shared across the academic, artisanal, and commercial aspects of instrumentation, and its narrative from the sixteenth to the eighteenth century was largely independent from other classes of device, in a period when a "scientific" instrument was unheard of.

  8. Early solar physics

    CERN Document Server

    Meadows, A J

    1970-01-01

    Early Solar Physics reviews developments in solar physics, particularly the advent of solar spectroscopy and the discovery of relationships between the various layers of the solar atmosphere and between the different forms of solar activity. Topics covered include solar observations during 1843; chemical analysis of the solar atmosphere; the spectrum of a solar prominence; and the solar eclipse of December 12, 1871. Spectroscopic observations of the sun are also presented. This book is comprised of 30 chapters and begins with an overview of ideas about the sun in the mid-nineteenth century, fo

  9. Early and late motherhood

    DEFF Research Database (Denmark)

    Christoffersen, Mogens; Lausten, Mette

    2009-01-01

    The study investigates parental child rearing methods, structural factors relating to the family during adolescence geographic segregation, individual resource deficits and social background of first time late live births among 32 to 37 years old women and compare to teenagers before becoming...... economic and social gradient for first-time teenage mothers. Teenagers who had experienced family separation or who were formerly in out-of-home care in particular had an increased risk of early childbearing. Results showed that teenage mothers were in every respect in a more disadvantaged position than...

  10. Early Reading and Concrete Operations.

    Science.gov (United States)

    Polk, Cindy L. Howes; Goldstein, David

    1980-01-01

    Indicated that early readers are more likely to be advanced in cognitive development than are nonearly-reading peers. After one year of formal reading instruction, early readers maintained their advantage in reading achievement. Measures of concrete operations were found to predict reading achievement for early and nonearly readers. (Author/DB)

  11. Early Childhood Workforce Index, 2016

    Science.gov (United States)

    Whitebook, Marcy; McLean, Caitlin; Austin, Lea J. E.

    2016-01-01

    The State of the Early Childhood Workforce (SECW) Initiative is a groundbreaking multi-year project to shine a steady spotlight on the nation's early childhood workforce. The SECW Initiative is designed to challenge entrenched ideas and policies that maintain an inequitable and inadequate status quo for early educators and for the children and…

  12. Radiation early warning system

    International Nuclear Information System (INIS)

    Schmitzer, C.; Kloesch, W.; Stadtmann, H.

    1993-01-01

    A prototype station for a Radiation Early Warning Network has been designed and set up at the Austrian Research Centre Seibersdorf. This unit was developed to measure all relevant parameters necessary to detect and track radioactive contamination at an early stage. The station consists of the following components: Radiation measuring channel for ambient gamma dose rate. Meteorological measurement channels for air temperature and humidity, wind direction and wind speed, and precipitation. Data processing and storage unit. The system is capable of unattended operation and data acquisition even under adverse environmental conditions. Connection to a central processing platform may be achieved via leased line, dial up over public switched telephone network (PSTN), or radio-frequency transmission. The remote station will continue acquiring and storing data for at least a month, even if the communications link is broken. Multiple stations can be combined to form a network, providing detailed information about radiological and meteorological data at each site. Thus increased ambient radiation levels may be discovered, tracked, and forecasted based on calculations using current and local weather data

  13. Sonority and early words

    DEFF Research Database (Denmark)

    Kjærbæk, Laila; Boeg Thomsen, Ditte; Lambertsen, Claus

    2015-01-01

    Syllables play an important role in children’s early language acquisition, and children appear to rely on clear syllabic structures as a key to word acquisition (Vihman 1996; Oller 2000). However, not all languages present children with equally clear cues to syllabic structure, and since the spec......Syllables play an important role in children’s early language acquisition, and children appear to rely on clear syllabic structures as a key to word acquisition (Vihman 1996; Oller 2000). However, not all languages present children with equally clear cues to syllabic structure, and since...... acquisition therefore presents us with the opportunity to examine how children respond to the task of word learning when the input language offers less clear cues to syllabic structure than usually seen. To investigate the sound structure in Danish children’s lexical development, we need a model of syllable......-29 months. For the two children, the phonetic structure of the first ten words to occur is compared with that of the last ten words to occur before 30 months of age, and with that of ten words in between. Measures related to the sonority envelope, viz. sonority types and in particular sonority rises...

  14. Planetary biology and microbial ecology. Biochemistry of carbon and early life

    Science.gov (United States)

    Margulis, L. (Editor); Nealson, K. H. (Editor); Taylor, I. (Editor)

    1983-01-01

    Experiments made with cyanobacteria, phototrophic bacteria, and methanogenic bacteria are detailed. Significant carbon isotope fractionation data is included. Taken from well documented extant microbial communities, this data provides a basis of comparison for isotope fractionation values measured in Archean and Proterozoic (preCambrian) rocks. Media, methods, and techniques used to acquire data are also described.

  15. Early-Onset Dementia

    DEFF Research Database (Denmark)

    Konijnenberg, Elles; Fereshtehnejad, Seyed-Mohammad; Kate, Mara Ten

    2017-01-01

    BACKGROUND: Early-onset dementia (EOD) is a rare condition, with an often atypical clinical presentation, and it may therefore be challenging to diagnose. Specialized memory clinics vary in the type of patients seen, diagnostic procedures applied, and the pharmacological treatment given. The aim...... of this study was to investigate quality-of-care indicators in subjects with EOD from 3 tertiary memory clinics in 3 European countries. METHODS: We included 1325 newly diagnosed EOD patients, ages 65 years or younger, between January 1, 2007 and December 31, 2013, from the Danish Dementia Registry...... (Rigshospitalet, Copenhagen), the Swedish Dementia Registry ("SveDem", Karolinska University Hospital, Stockholm), and the Amsterdam Dementia Cohort (VU University Medical Center). RESULTS: The frequency of EOD among all dementia patients was significantly lower in Copenhagen (410, 20%) and Stockholm (284, 21...

  16. Early Tertiary Exhumation, Erosion, and Sedimentation in the Central Andes, NW Argentina

    Science.gov (United States)

    Carrapa, B.; Decelles, P. G.; Gerhels, G.; Mortimer, E.; Strecker, M. R.

    2006-12-01

    Timing of deformation and resulting sedimentation patterns in the Altiplano-Puna Plateau-Eastern Cordillera of the southern Central Andes are the subject of ongoing controversial debate. In the Bolivian Altiplano, sedimentation into a foreland basin system commenced during the Paleocene. Farther south in the Puna and Eastern Cordillera of NW Argentina, a lack of data has precluded a similar interpretation. Early Tertiary non-marine sedimentary rocks are preserved within the present day Puna Plateau and Eastern Cordillera of NW Argentina. The Salar de Pastos Grandes basin in the Puna Plateau contains more than 2 km of Eocene alluvial and fluvial strata in the Geste Formation, deposited in close proximity to orogenic source terrains. Sandstone and conglomerate petrographic data document Ordovician quartzites and minor phyllites and schists as the main source rocks. Detrital zircon U-Pb ages from both the Geste Formation and from underlying Ordovician quartzite cluster in the 900-1200 Ma (Grenville) and late Precambrian-Cambrian (Panafrican) ranges. Sparse late Eocene (~37-34 Ma) grains are also present; their large size, euhedral shape, and decreasing mean ages upsection suggest that these grains are volcanogenic (i.e. ash fall contamination), derived from an inferred magmatic arc to the west. The Eocene ages corroborate mammalian paleontological dates, defining the approximate begin of deposition of the Geste Formation. Alternatively, these young zircons could be of plutonic origin; however, no Eocene plutons are present in the surrounding source rocks and this interpretation is not likely. From W to E, fluvial rocks of the Quebrada de los Colorados Formation show similar sedimentological features as those observed for the Geste Formation, suggesting a genetic link between the two. Detrital zircon U-Pb data show mainly Panafrican ages, with sparse ages in the 860-935 Ma range and a few mid-Proterozoic ages. More importantly, a significant number of late Eocene

  17. Analysis of lineament swarms in a Precambrian metamorphic rocks ...

    Indian Academy of Sciences (India)

    The application of domain-based filtering techniques identifies a ... ation of lineaments from dominant joint/fractures. (Lattman and .... Georient software has been used for quantitative ..... Blanchet P H 1957 Development of fracture analysis as.

  18. Hydrogen isotopes as a tracer of the Precambrian hydrosphere

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Rosing, Minik Thorleif; Bird, Dennis K.

    the formation of Isua serpentines would require that either continental growth must have happened primarily before 3.8 Ga, and/or methane was not a significant atmospheric gas in the Eoarchean. Developing a more robust geological record of δDSEAWATER using other well-preserved vestiges of hydrated ocean crust...

  19. Geological site selection studies in Precambrian crystalline rocks in Finland

    International Nuclear Information System (INIS)

    Vuorela, P.

    1988-01-01

    In general geological investigations made since 1977 the Finnish crystalline bedrock has been determined to be suitable for the final disposal of the spent nuclear fuel. Regional investigations have been mainly based on already existing geological studies. Special attention has been paid on the international geological Finland as the Baltic Shield is stiff and stable and situated far outside the zones of volcanic and seismic activity. The present day crustal movements in Finland are related to landuplift process. Movements and possible faults in the bedrock follow fracture zones which devide the bedrock into mosaiclike blocks. As compared to small scale geological maps the bedrock blocks are often indicated as large granite rock formations which are less broken than the surrounding rocks, though the age of granite formations is at least 1500 millions of years. The large bedrock blocks (20-300 km 2 ) are divided to smaller units by different magnitudes of fractures and these smaller bedrock units (5-20 km 2 ) have been selected for further site selection investigations. At the first stage of investigations 327 suitable regional bedrock blocks have been identified on the basis of Landsat-1 winter and summer mosaics of Finland. After two years of investigations 134 investigation areas were selected inside 61 bedrock blocks and classified to four priority classes, the three first of which were redommended for further investigations. Geological criteries used in classification indicated clear differences between the classes one and three, however all classified areas are situated in large rather homogenous bedrock blocks and more exact three dimensional suitability errors may not be observed until deep bore holes have been made

  20. Technetium behaviour in soils of the Canadian precambrian shield

    International Nuclear Information System (INIS)

    Sheppard, M.I.; Sheppard, S.C.

    1986-01-01

    The first experiment clearly showed that Tc mobility is lower in soil under reducing conditions, but that the water-table interface itself is not a barrier to the upward migration of Tc. The second experiment showed that, despite the very low Ksub(d) values (< 0.05 ml/g) measured in the laboratory, an undisturbed sandy soil profile retained 71% of its original Tc spike, placed just below the litter, after one year. In the third experiment, no Tc has reached the surface after three months, from placement 40 cm deep in either a natural sphagnum or a reed/sedge peat core. Under anoxic conditions, Ksub(d) values for Tc varied from about 3 ml/g in the sphagnum to 100 and 340 ml/g for the reed/sedge peat, indicating that the floristic composition of organic soils may strongly affect the migration of Tc in a swamp or bog. (author)

  1. The South India Precambrian crust and shallow lithospheric mantle ...

    Indian Academy of Sciences (India)

    Regional geothermal-barometry in the granulite facies terrane of South India; Contrib. Mineral. Petrol. 73. 221–244. Raith M, Karmakar S and Brown M 1997 Ultra high temparature metamorphism and multi-stage decom- pressional of saphirrine granulite from the Palni-. Hill ranges, southern India; J. Metamorph. Geol. 15.

  2. A petrographic study of Precambrian quartzites from Goa coast

    Digital Repository Service at National Institute of Oceanography (India)

    Wagle, B.G.; Rajamanickam, G.V.

    tourmaline, topaz, zircon, rutile, fluorite, apatite and hornblende lead to a source of acidic composition. The introduction of tourmaline and fluorite in the wacke, the grade of metamorphism and the source of the wacke have been discussed...

  3. Evaluation of mineral resource potential of the Finnish precambrian

    International Nuclear Information System (INIS)

    Peltonen, K.

    1993-05-01

    In the report the undiscovered mineral resource potential of metallogenic regions in Finland is evaluated. The evaluation is based on known deposits. The criteria of the evaluation were: ore and mineral deposit density, regional distribution of valuable metals, and the amount and the nature of prospecting methods used. The information for the study has been collected from the data base for ore minerals maintained by the Geological Survey of Finland. Regions with mineral resource potential conclusively under national average are Presvecokarelidic and Svecokarelidic granitoids and rapakivi Massif. The mineral resource potential of basic rocks in relation to their surface area is multiple compared to non-basic rocks

  4. Fault distribution in the Precambrian basement of South Norway

    Science.gov (United States)

    Gabrielsen, Roy H.; Nystuen, Johan Petter; Olesen, Odleiv

    2018-03-01

    Mapping of the structural pattern by remote sensing methods (Landsat, SPOT, aerial photography, potential field data) and field study of selected structural elements shows that the cratonic basement of South Norway is strongly affected by a regular lineament pattern that encompasses fault swarms of different orientation, age, style, attitude and frequency. Albeit counting numerous fault and fracture populations, the faults are not evenly distributed and N-S to NNE-SSW/NNW-SSE and NE-SE/ENE-WSW-systems are spatially dominant. N-S to NNW-SSE structures can be traced underneath the Caledonian nappes to the Western Gneiss Region in western and central South Norway, emphasizing their ancient roots. Dyke swarms of different ages are found within most of these zones. Also, the Østfold, Oslo-Trondheim and the Mandal-Molde lineament zones coincide with trends of Sveconorwegian post-collision granites. We conclude that the N-S-trend includes the most ancient structural elements, and that the trend can be traced back to the Proterozoic (Svecofennian and Sveconorwegian) orogenic events. Some of the faults may have been active in Neoproterozoic times as marginal faults of rift basins at the western margin of Baltica. Remnants of such fault activity have survived in the cores of many of the faults belonging to this system. The ancient systems of lineaments were passively overridden by the Caledonian fold-and-thrust system and remained mostly, but note entirely inactive throughout the Sub-Cambrian peneplanation and the Caledonian orogenic collapse in the Silurian-Devonian. The system was reactivated in extension from Carboniferous times, particularly in the Permian with the formation of the Oslo Rift and parts of it remain active to the Present, albeit by decreasing extension and fault activity.

  5. A lithospheric perspective on structure and evolution of Precambrian cratons

    DEFF Research Database (Denmark)

    Artemieva, Irina

    2012-01-01

    The purpose of this chapter is to provide a summary of geophysical data on the structure of the stable continental lithosphere and its evolution since the Archean. Here, the term lithosphere is used to define the outer layer of the Earth which includes the crust and uppermost mantle, forms the ro...

  6. Manipulating early pig embryos.

    Science.gov (United States)

    Niemann, H; Reichelt, B

    1993-01-01

    On the basis of established surgical procedures for embryo recovery and transfer, the early pig embryo can be subjected to various manipulations aimed at a long-term preservation of genetic material, the generation of identical multiplets, the early determination of sex or the alteration of the genetic make-up. Most of these procedures are still at an experimental stage and despite recent considerable progress are far from practical application. Normal piglets have been obtained after cryopreservation of pig blastocysts hatched in vitro, whereas all attempts to freeze embryos with intact zona pellucida have been unsuccessful. Pig embryos at the morula and blastocyst stage can be bisected microsurgically and the resulting demi-embryos possess a high developmental potential in vitro, whereas their development in vivo is impaired. Pregnancy rates are similar (80%) but litter size is reduced compared with intact embryos and twinning rate is approximately 2%. Pig blastomeres isolated from embryos up to the 16-cell stage can be grown in culture and result in normal blastocysts. Normal piglets have been born upon transfer of blastocysts derived from isolated eight-cell blastomeres, clearly underlining the totipotency of this developmental stage. Upon nuclear transfer the developmental capacity of reconstituted pig embryos is low and culture. Sex determination can be achieved either by separation of X and Y chromosome bearing spermatozoa by flow cytometry or by analysing the expression of the HY antigen in pig embryos from the eight-cell to morula stage. Microinjection of foreign DNA has been successfully used to alter growth and development of transgenic pigs, and to produce foreign proteins in the mammary gland or in the bloodstream, indicating that pigs can be used as donors for valuable human pharmaceutical proteins. Another promising area of gene transfer is the increase of disease resistance in transgenic lines of pigs. Approximately 30% of pig spermatozoa bind

  7. EARLY ENTRANCE COPRODUCTION PLANT

    Energy Technology Data Exchange (ETDEWEB)

    John S. Abughazaleh; Mushtaq Ahmed; Ashok Anand; John H. Anderson; Charles Benham; Fred D. Brent; Thomas E. Chance; William K. Davis; Raymond F. Drnevich; Larry Hall; Ming He; Stephen A. Lang; David Mintner; Wendy Moore; Jimmy O. Ong; George Potoczniak; Adela G. Sanchez; Charles H. Schrader; Lalit S. Shah; Kalapi D. Sheth; Phil J. Shires; Rae Song

    2001-05-17

    The overall objective of this project is the three-phase development of an Early Entrance Coproduction Plant (EECP) that produces at least one product from at least two of the following three categories: Electric power (or heat); Fuels; and Chemicals. The objective is to have these products produced by technologies capable of using synthesis gas derived from coal and/or some other carbonaceous feedstock, such as petroleum coke. The objective of Phase I was to determine the feasibility and define the concept for the EECP located at a specific site and to develop a Research, Development, and Testing (RD and T) Plan for implementation in Phase II. This objective has now been accomplished. A specific site, Motiva Refinery in Port Arthur, Texas, has been selected as the location best suited for the EECP. The accomplishments of Phase I are discussed in detail in this Phase I Concept Report. A RD and T Plan and a preliminary project financing plan have been developed and are submitted separately from this report.

  8. The Early Experiments

    Science.gov (United States)

    Garvey, Gerald

    2013-04-01

    Stuart Freedman obtained his PhD at Berkley with an experimental thesis providing very strong evidence against theories requiring local hidden variables. He then came to Princeton in 1972 and began collaboration on a search for second-class currents. These measurements are quite difficult as the effects are the order of 1%, demonstrating Freedman's drive to take on hard but important experiments. After carrying out some relatively standard nuclear physics measurements he moved on to Stanford in 1976. There, Freedman was involved in identifying measurements sensitive to the existence of light axions. He also carried out searches for various exotica that might be produced from cosmic rays or the SLAC beam stop. During this time he was collaborating with us at Argonne investigating nuclear parity violation and time-like axial beta decay. In 1982 Freedman came to Argonne where he worked on fundamental issues in neutron beta decay. He also initiated what was to become one of his trademarks, demonstrating that surprising peaks in the e^+-e^- spectrum observed in very heavy ion collisions were spurious. He further launched his first neutrino oscillation experiment. This period of early research was marked by a remarkable diversity of subject matter and approach.

  9. Early diagnosis of leptospirosis

    Directory of Open Access Journals (Sweden)

    Andrea Babic-Erceg

    2014-06-01

    Full Text Available A 25-years old man from Zagreb, Croatia, was admitted to the University Hospital for Infectious Diseases four days after the onset of symptoms such as fever, intense pain in the calves and anuria. The patient owned a rabbit and, before the onset of the disease, repaired some rubber pipes damaged by rodents. At admission, he had a severe clinical picture with fever, hypotension, jaundice, immobility, and pain in leg muscles. Treatment with ceftriaxone was initiated in combination with volume restitution. Renal failure soon ensued. Consequently continuous venovenous hemodiaphiltration therapy was performed. Due to acute respiratory distress syndrome, the patient was mechanically ventilated. The patient’s condition gradually improved and he recovered fully from multi-organ failure. Diagnosis was confirmed by a microscopic agglutination test (MAT covering 15 leptospira serovars and real-time polymerase-chain reaction (PCR. The first serum sample taken on day 6 tested negative for leptospira, while PCR showed positive results for leptospiral DNA. The second serum sample taken on day 13 tested positive for serovar Canicola serogroup Canicola, serovar Patoc, serovar Grippotyphosa serogroup Grippotyphosa and serovar Tarassovi serogroup Tarassovi (titre 4000, 4000, 1000 and 2000, respectively, while PCR was negative. This report highlights the benefits of combining MAT and PCR methods in early diagnosis of leptospirosis.

  10. EARLY ENTRANCE COPRODUCTION PLANT

    International Nuclear Information System (INIS)

    William K. Davis

    2001-01-01

    The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which produces at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals. The objective is to have these products produced by technologies capable of using synthesis gas derived from coal and/or other carbonaceous feedstocks. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site; develop a Research, Development, and Testing (RD and T) Plan for implementation in Phase II; and prepare a Preliminary Project Financing Plan. The objective of Phase II is to implement the work as outlined in the Phase I RD and T Plan to enhance the development and commercial acceptance of coproduction technology that produces high-value products, particularly those that are critical to our domestic fuel and power requirements. The project will resolve critical knowledge and technology gaps on the integration of gasification and downstream processing to coproduce some combination of power, fuels, and chemicals from coal and/or other carbonaceous feedstocks. The objective of Phase III is to develop an engineering design package and a financing plan for an EECP located at a specific site. The project's intended result is to provide the necessary technical, economic, and environmental information needed by industry to move the EECP forward to detailed design, construction, and operation

  11. Is credit for early action credible early action?

    International Nuclear Information System (INIS)

    Rolfe, C.; Michaelowa, A.; Dutschke, M.

    1999-12-01

    Credit for early action as a tool for greenhouse gas emissions reduction is compared with various market instruments as a means of narrowing the gap between projected emissions and those of the Kyoto Protocol. Market instruments work by creating a market price for emissions and use the market to encourage reductions at the lowest price, which is done by placing limits on greenhouse gas emissions and allowing the market to decide where reductions occur, or by imposing a carbon tax or emissions charge. While they can be applied within a sector, they are usually used to encourage reductions throughout the economy or across large sectors. Credit for early action also creates an incentive for emissions reductions throughout the economy or at least across many sectors. Credit for early action tools do not work by either imposing a carbon tax or emissions charge or placing limits on emissions, rather they promise that entities that take action against greenhouse gases prior to the imposition of a carbon tax or emissions limits will receive a credit against future taxes or limits. An overview is provided of the Kyoto Protocol and the rationale for taking early action, and a review is included of the theory and specific proposals for market instruments and credit for early action. A comparative analysis is provided of these approaches by examining their relative efficiency, environmental effectiveness, and impacts on the redistribution of wealth. Credit for early action is viewed as problematic on a number of counts and is seen as an interim strategy for imposition while political support for market instruments develop. The environmental effectiveness of credit for early action is very difficult to predict, and credit for early action programs do not yield the lowest cost emissions reductions. Credit for early action programs will not achieve compliance with the Kyoto Protocol at the lowest cost, and credits for early action will increase the compliance costs for those who

  12. 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

  13. Early tetrapod relationships revisited.

    Science.gov (United States)

    Ruta, Marcello; Coates, Michael I; Quicke, Donald L J

    2003-05-01

    In an attempt to investigate differences between the most widely discussed hypotheses of early tetrapod relationships, we assembled a new data matrix including 90 taxa coded for 319 cranial and postcranial characters. We have incorporated, where possible, original observations of numerous taxa spread throughout the major tetrapod clades. A stem-based (total-group) definition of Tetrapoda is preferred over apomorphy- and node-based (crown-group) definitions. This definition is operational, since it is based on a formal character analysis. A PAUP* search using a recently implemented version of the parsimony ratchet method yields 64 shortest trees. Differences between these trees concern: (1) the internal relationships of aïstopods, the three selected species of which form a trichotomy; (2) the internal relationships of embolomeres, with Archeria crassidisca and Pholiderpeton scut collapsed in a trichotomy with a clade formed by Anthracosaurus russelli and Pholiderpeton attheyi; (3) the internal relationships of derived dissorophoids, with four amphibamid species forming an unresolved node with a clade consisting of micromelerpetontids and branchiosaurids and a clade consisting of albanerpetontids plus basal crown-group lissamphibians; (4) the position of albenerpetontids and Eocaecilia micropoda, which form an unresolved node with a trichotomy subtending Karaurus sharovi, Valdotriton gracilis and Triadobatrachus massinoti; (5) the branching pattern of derived diplocaulid nectrideans, with Batrachiderpeton reticulatum and Diceratosaurus brevirostris collapsed in a trichotomy with a clade formed by Diplocaulus magnicornis and Diploceraspis burkei. The results of the original parsimony run--as well as those retrieved from several other treatments of the data set (e.g. exclusion of postcranial and lower jaw data; character reweighting; reverse weighting)--indicate a deep split of early tetrapods between lissamphibian- and amniote-related taxa. Colosteids, Crassigyrinus

  14. Early onset sebaceous carcinoma

    Directory of Open Access Journals (Sweden)

    Kaltreider Sara A

    2011-09-01

    Full Text Available Abstract Background Ocular sebaceous carcinoma can masquerade as benign lesions resulting in delay of diagnosis. Early recognition is even more difficult in young patients where the disease rarely occurs. Here, we provide a clinicopathological correlation of ocular sebaceous carcinoma in a young individual lacking history of hereditary cancer or immunosuppression. Findings A detailed histopathological study including p53 DNA sequencing was performed on an aggressive sebaceous carcinoma presenting in a healthy 32 year-old Caucasian woman. She had no history of retinoblastoma, evidence for a hereditary cancer syndrome, or radiation therapy. However, she potentially was at risk for excessive UV light exposure. A detailed review of the literature is also provided. A moderately well differentiated sebaceous carcinoma was established histopathologically arising from the meibomian gland of the upper eyelid. In most areas, the cytoplasm contained small but distinct Oil-red-O positive vacuoles. Direct sequencing of p53 identified a G:C→A:T mutation at a dipyrimidine site. The mutation results in substitution of arginine for the highly conserved glycine at residue 199 located at the p53 dimer-dimer interface. Energy minimization structural modeling predicts that G199R will neutralize negative charges contributed by nearby inter- and intramonomeric glutamate residues. Discussion This study points to the importance of recognizing that sebaceous carcinoma can occur in young patients with no evidence for hereditary cancer risk or radiation therapy. The G199R substitution is anticipated to alter the stability of the p53 tetrameric complex. The role of UV light in the etiology of sebaceous carcinoma deserves further study. Our findings, taken together with those of others, suggest that different environmental factors could lead to the development of sebaceous carcinoma in different patients.

  15. Early determinants of mental health

    NARCIS (Netherlands)

    Räikkönen, Katri; Pesonen, Anu-Katriina; Roseboom, Tessa J.; Eriksson, Johan G.

    2012-01-01

    Environmental adversities in pre- and early postnatal life may have life-long consequences. Based upon a series of epidemiological and clinical studies and natural experiments, this review describes how the early life environment may affect psychological functions and mental disorders later in life.

  16. Early Childhood Education in Taiwan.

    Science.gov (United States)

    Barclay, Lisa K.

    1989-01-01

    Describes early childhood education in Taiwan, focusing on living patterns and child care arrangements, the position of the individual within the family and community, and the application of cultural norms to early childhood education. Compares the behavior of Chinese preschool children to that of American preschool children. (RJC)

  17. Cell Analysis and Early Diagnostics

    NARCIS (Netherlands)

    Subramaniam, Vinod; Jones, Val

    2006-01-01

    In an era of aging populations and rising health-care costs, the shift of medical paradigms towards rapid, accurate, early diagnoses of diseases is inevitable. In addition to further development of ultrasensitive in vitro tests, the focus of attention in both diagnostics and the early drug discovery

  18. Early Childhood Inclusion in Spain

    Science.gov (United States)

    Giné, Climent; Balcells-Balcells, Anna; Cañadas, Margarita; Paniagua, Gema

    2016-01-01

    This article describes early childhood inclusion in educational settings in Spain. First, we address the legislative framework of preschool education in Spain and offer a brief analysis of some relevant issues, including the current situation of early childhood education and inclusion at this stage. Second, current policies and practices relating…

  19. Early diagnosis and early intervention in cerebral palsy

    Directory of Open Access Journals (Sweden)

    Mijna eHadders-Algra

    2014-09-01

    Full Text Available This paper reviews the opportunities and challenges for early diagnosis and early intervention in cerebral palsy (CP. CP describes a group of disorders of the development of movement and posture, causing activity limitation, that are attributed to disturbances that occurred in the fetal or infant brain. Therefore the paper starts with a summary of relevant information from developmental neuroscience. Most lesions underlying CP occur in the second half of gestation, when developmental activity in the brain reaches its summit. Variations in timing of the damage not only result in different lesions, but also in different neuroplastic reactions and different associated neuropathologies. This turns CP into a heterogeneous entity. This may mean that the best early diagnostics and the best intervention methods may differ for various subgroups of children with CP. Next, the paper addresses possibilities for early diagnosis. It discusses the predictive value of neuromotor and neurological exams, neuro-imaging techniques and neurophysiological assessments. Prediction is best when complementary techniques are used in longitudinal series. Possibilities for early prediction of CP differ for infants admitted to neonatal intensive care and other infants. In the former group best prediction is achieved with the combination of neuro-imaging and the assessment of general movements, in the latter group best prediction is based on carefully documented milestones and neurological assessment. The last part reviews early intervention in infants developing CP. Most knowledge on early intervention is based on studies in high risk infants without CP. In these infants early intervention programs promote cognitive development until preschool age; motor development profits less. The few studies on early intervention in infants developing CP suggest that programs that stimulate all aspects of infant development by means of family coaching are most promising. More research is

  20. A comparative analysis of two Early Palaeozoic marine impact structures in Estonia, Baltic Sea: Neugrund and Kärdla

    Directory of Open Access Journals (Sweden)

    Sten Suuroja

    2013-07-01

    Full Text Available Kärdla and Neugrund are two Early Palaeozoic offshore impact structures located some 50 km apart along the Estonian coast of the Baltic Sea. They share many similarities but differing features are also found. The Kärdla impact structure is located at the NE coastof Hiiumaa Island (58°58’N, 22°46’E. The inner crater has a 4 km rim-to-rim diameter and a c. 130 m high central uplift, surrounded by a ring fault, c. 12 km in diameter. The well-preserved buried inner crater is outlined in the landscape by a circular ridge of upliftedbedrock. The perimeter of the outer crater is outlined on the seafloor by a semicircular ridge of narrow shoals. The variable height of the rim wall (50–240 m above the crystalline basement level and the asymmetric location of the inner crater is obviously a result of an oblique impact in a layered target and partial collapse of the rim wall. Shortly after the impact in a shallow epicontinental sea during Late Ordovician time (c. 455 My, calcareous biodetritic muds were deposited and the crater was buried. The Neugrund impact structure is located in the seabed at the entrance of the Gulf of Finland (59°20’N, 23°31’E. The inner crater has a 7 km rim-to-rim diameter and the outer limit of the structure passes through the Osmussaar Island to the southwest of the impact centre. The crater wasburied in a shallow epicontinental sea with siliciclastic deposition shortly after the impact at Early Cambrian time, c. 535 My. It was partially re-exposed by erosion during Pliocene. The target had a three-layered composition: Precambrian metamorphic rocks covered byEdiacaran and Early Cambrian siliciclastic rocks (c. 150 m and water (c. 100 m. The structure has been studied with seismoacoustic and sidescan sonar profiling, and by diving and sampling of submarine outcrops. Several hundred samples of impact breccias have been collected and investigated from erratic boulders distributed by glacial action in the west

  1. Early Maternal Time Investment and Early Child Outcomes

    OpenAIRE

    Del Bono, Emilia; Francesconi, Marco; Kelly, Yvonne; Sacker, Amanda

    2014-01-01

    Using large longitudinal survey data from the UK Millennium Cohort Study, this paper estimates the relationship between maternal time inputs and early child development. We find that maternal time is a quantitatively important determinant of skill formation and that its effect declines with child age. There is evidence of long-term effects of early maternal time inputs on later outcomes, especially in the case of cognitive skill development. In the case of non-cognitive development, the evide...

  2. EARLY ENTRANCE COPRODUCTION PLANT

    Energy Technology Data Exchange (ETDEWEB)

    Fred D. Brent; Lalit Shah; Earl Berry; Charles H. Schrader; John Anderson; Ming He; James F. Stevens; Centha A. Davis; Michael Henley; Jerome Mayer; Harry Tsang; Jimell Erwin; Jennifer Adams; Michael Tillman; Chris Taylor; Marjan J. Roos; Robert F. Earhart

    2004-01-27

    The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which uses petroleum coke to produce at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals using ChevronTexaco's proprietary gasification technology. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site; develop a Research, Development, and Testing (RD&T) Plan to mitigate technical risks and barriers; and prepare a Preliminary Project Financing Plan. The objective of Phase II is to implement the work as outlined in the Phase I RD&T Plan to enhance the development and commercial acceptance of coproduction technology. The objective of Phase III is to develop an engineering design package and a financing and testing plan for an EECP located at a specific site. The project's intended result is to provide the necessary technical, economic, and environmental information needed by industry to move the EECP forward to detailed design, construction, and operation. The partners in this project are Texaco Energy Systems LLC or TES (a subsidiary of ChevronTexaco), General Electric (GE), Praxair, and Kellogg Brown & Root (KBR) in addition to the U.S. Department of Energy (DOE). TES is providing gasification technology and Fischer-Tropsch (F-T) technology developed by Rentech, GE is providing combustion turbine technology, Praxair is providing air separation technology, and KBR is providing engineering. Each of the EECP subsystems was assessed for technical risks and barriers. A plan was developed to mitigate the identified risks (Phase II RD&T Plan, October 2000). The potential technical and economic risks to the EECP from Task 2.5 can be mitigated by demonstrating that the end-use products derived from the upgrading of the F-T synthesis total liquid product can meet or exceed current specifications for the

  3. Early vision and visual attention

    Directory of Open Access Journals (Sweden)

    Gvozdenović Vasilije P.

    2003-01-01

    Full Text Available The question whether visual perception is spontaneous, sudden or is running through several phases, mediated by higher cognitive processes, was raised ever since the early work of Gestalt psychologists. In the early 1980s, Treisman proposed the feature integration theory of attention (FIT, based on the findings of neuroscience. Soon after publishing her theory a new scientific approach appeared investigating several visual perception phenomena. The most widely researched were the key constructs of FIT, like types of visual search and the role of the attention. The following review describes the main studies of early vision and visual attention.

  4. Geochemistry and Nd-Sr isotopic signatures of the Pensamiento Granitoid Complex, Rondonian-San Ignacio Province, eastern precambrian shield of Bolivia: petrogenetic constraints for a mesoproterozoic magmatic arc setting;Geoquimica e assinaturas Nd-Sr do Complexo Granitoide Pensamiento, provincia Rondoniana-San Ignacio, pre-cambriano de Bolivia Oriental: caracterizacao petrogenetica de um arco magmatico no mesoproterozoico

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Ramiro, E-mail: rmatoss@igc.usp.b [Universidad Mayor de San Andre (UMSA), La Paz (Bolivia, Plurinational State of). Inst. de Investigaciones Geologicas y del Medio Ambiente; Teixeira, Wilson; Bettencourt, Jorge Silva, E-mail: wteixeir@usp.b, E-mail: jsbetten@usp.b [Universidade de Sao Paulo (IGC/USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica; Geraldes, Mauro Cesar, E-mail: geraldes@uerj.b [Universidade do Estado do Rio de Janeiro (FG/UERJ), RJ (Brazil). Faculdade de Geologia

    2009-07-01

    The Pensamiento Granitoid Complex (PGC), located in the northern part of the eastern Precambrian shield of Bolivia, is tectonically assigned to the Rondonian-San Ignacio Province (1.55 - 1.30 Ga) of the Amazonian Craton that is made up by Archean and Proterozoic provinces. The Proterozoic ones result from accretionary orogens that become successively younger south westwards, such as the Rondonian/San Ignacio (1.37 - 1.32 Ga) and the Sunsas orogenies (1.20 - 1.00 Ga). The PGC crops out mainly on the 'Paragua craton' bounded to the south by the Sunsas belt, and composed of granites and subvolcanic terms, and subordinately of syenites, granodiorites, tonalites, trondhjemites and diorites as orogenic representatives of the Rondonian/San Ignacio Orogeny, intrusive into the Lomas Maneches (ca. 1.68 Ga) and Chiquitania (ca. 1.7 Ga) complexes. Thirteen whole rock chemical analyses for major, trace and REE elements were performed for the La Junta, San Martin, Diamantina, Porvernir, San Cristobal, Piso Firme plutons of the PGC. The negative trends of MgO, Al{sub 2}O{sub 3} and CaO contents with increasing SiO{sub 2} suggest that fractional crystallization played an important role in the petrogenesis of the investigated rocks. The data also indicate a mainly peraluminous, sub-alkaline to high-K calc-alkaline composition, and fractionated LREE/HREE patterns are consistent with a magmatic arc character for these plutons. SHRIMP U-Pb zircon ages of the La Junta and San Martin syn- to late-kinematic plutons are 1347 {+-} 21 Ma and 1373 {+-} 20 Ma respectively, and the Sm-Nd T{sub DM} model ages are between 1.9 to 2.0 Ga, while {epsilon}{sub Nd(1330)} values range from +1.8 to -4.3, respectively. In addition, the late- to post-kinematic Diamantina pluton yields SHRIMP U-Pb zircon age of 1340 {+-} 20 Ma, and variable Sm-Nd T{sub DM} model ages (1.6 to 1.9 Ga) and {epsilon}{sub Nd(1330)} values (+0.4 to -1.2) that are comparable with previous results found for other coeval

  5. FAA Loran early implementation project

    Science.gov (United States)

    1990-03-01

    The Early Implementation Project (EIP), established by FAA Administrator Admiral : Donald C. Engen, was the initial step in the process of Loran integration into the : National Airsace System (NAS). The EIP was designed to give the FAA and the Loran ...

  6. Hypertension presenting early in pregnancy

    OpenAIRE

    Melvin, Audrey; Kinsley, Brendan

    2015-01-01

    Key Clinical Message Paraganglioma in pregnancy is an exceedingly rare and potentially life?threatening diagnosis. It is important that the clinicians consider secondary causes when women present with hypertension in early pregnancy.

  7. Early onset type 2 diabetes

    DEFF Research Database (Denmark)

    Bo, A; Thomsen, R W; Nielsen, J S

    2018-01-01

    was more frequent and meeting physical activity recommendations less likely in persons with early-onset type 2 DM. CONCLUSIONS: We found a clear age-gradient, with increasing prevalence of clinical and behavioural risk factors the younger the onset age of type 2 DM. Younger persons with early-onset type 2......AIM: To examine the association between early onset of type 2 diabetes (DM) and clinical and behavioural risk factors for later diabetes complications. METHODS: We conducted a cross-sectional study of 5115 persons with incident type 2 DM enrolled during 2010-2015 in the Danish Centre for Strategic...... Research in Type 2 Diabetes-cohort. We compared risk factors at time of diagnosis among those diagnosed at ≤45 years (early-onset) with diagnosis age 46-55, 56-65 (average-onset = reference), 66-75, and >75 years (late-onset). Prevalence ratios (PRs) were computed using Poisson regression. RESULTS: Poor...

  8. [Early management of cerebrovascular accidents].

    Science.gov (United States)

    Libot, Jérômie; Guillon, Benoit

    2013-01-01

    A cerebrovascular accident requires urgent diagnosis and treatment.The management of a stroke must be early and adapted in order to improve the overall clinical outcome and lower the risk of mortality.

  9. Early Identification of Reading Difficulties

    DEFF Research Database (Denmark)

    Poulsen, Mads; Nielsen, Anne-Mette Veber; Juul, Holger

    2017-01-01

    Early screening for reading difficulties before the onset of instruction is desirable because it allows intervention that is targeted at prevention rather than remediation of reading difficulties. However, early screening may be too inaccurate to effectively allocate resources to those who need...... them. The present study compared the accuracy of early screening before the onset of formal reading instruction with late screening six months into the first year of instruction. The study followed 164 Danish students from the end of Grade 0 to the end of Grade 2. Early screening included measures...... of phonemic awareness, rapid naming, letter knowledge, paired associate learning, and reading. Late screening included only reading. Results indicated that reading measures improved substantially as predictors over the first six months of Grade 1, to the point where late reading measures alone provided...

  10. Early Retiree Reinsurance Program Reports

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Early Retiree Reinsurance Program (ERRP) was established by section 1102 of the Patient Protection and Affordable Care Act (the Affordable Care Act) enacted on...

  11. EARLY ENTRANCE COPRODUCTION PLANT

    Energy Technology Data Exchange (ETDEWEB)

    Fred D. Brent; Lalit Shah; Earl Berry; Charles H. Schrader; John Anderson; J. Erwin; Matthew G. Banks; Terry L. Ullman

    2004-01-12

    The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which uses petroleum coke to produce at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals using ChevronTexaco's proprietary gasification technology. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site; develop a Research, Development, and Testing (RD&T) Plan to mitigate technical risks and barriers; and prepare a Preliminary Project Financing Plan. The objective of Phase II is to implement the work as outlined in the Phase I RD&T Plan to enhance the development and commercial acceptance of coproduction technology. The objective of Phase III is to develop an engineering design package and a financing and testing plan for an EECP located at a specific site. The project's intended result is to provide the necessary technical, economic, and environmental information needed by industry to move the EECP forward to detailed design, construction, and operation. The partners in this project are Texaco Energy Systems LLC or TES (a subsidiary of ChevronTexaco), General Electric (GE), Praxair, and Kellogg Brown & Root (KBR) in addition to the U.S. Department of Energy (DOE). TES is providing gasification technology and Fischer-Tropsch (F-T) technology developed by Rentech, GE is providing combustion turbine technology, Praxair is providing air separation technology, and KBR is providing engineering. Each of the EECP subsystems was assessed for technical risks and barriers. A plan was developed to mitigate the identified risks (Phase II RD&T Plan, October 2000). Phase II RD&T Task 2.6 identified as potential technical risks to the EECP the fuel/engine performance and emissions of the F-T diesel fuel products. Hydrotreating the neat F-T diesel product reduces potentially reactive olefins, oxygenates, and acids

  12. Early Intervention in Bipolar Disorder.

    Science.gov (United States)

    Vieta, Eduard; Salagre, Estela; Grande, Iria; Carvalho, André F; Fernandes, Brisa S; Berk, Michael; Birmaher, Boris; Tohen, Mauricio; Suppes, Trisha

    2018-05-01

    Bipolar disorder is a recurrent disorder that affects more than 1% of the world population and usually has its onset during youth. Its chronic course is associated with high rates of morbidity and mortality, making bipolar disorder one of the main causes of disability among young and working-age people. The implementation of early intervention strategies may help to change the outcome of the illness and avert potentially irreversible harm to patients with bipolar disorder, as early phases may be more responsive to treatment and may need less aggressive therapies. Early intervention in bipolar disorder is gaining momentum. Current evidence emerging from longitudinal studies indicates that parental early-onset bipolar disorder is the most consistent risk factor for bipolar disorder. Longitudinal studies also indicate that a full-blown manic episode is often preceded by a variety of prodromal symptoms, particularly subsyndromal manic symptoms, therefore supporting the existence of an at-risk state in bipolar disorder that could be targeted through early intervention. There are also identifiable risk factors that influence the course of bipolar disorder, some of them potentially modifiable. Valid biomarkers or diagnosis tools to help clinicians identify individuals at high risk of conversion to bipolar disorder are still lacking, although there are some promising early results. Pending more solid evidence on the best treatment strategy in early phases of bipolar disorder, physicians should carefully weigh the risks and benefits of each intervention. Further studies will provide the evidence needed to finish shaping the concept of early intervention. AJP AT 175 Remembering Our Past As We Envision Our Future April 1925: Interpretations of Manic-Depressive Phases Earl Bond and G.E. Partridge reviewed a number of patients with manic-depressive illness in search of a unifying endo-psychic conflict. They concluded that understanding either phase of illness was "elusive" and

  13. Early vision and visual attention

    OpenAIRE

    Gvozdenović Vasilije P.

    2003-01-01

    The question whether visual perception is spontaneous, sudden or is running through several phases, mediated by higher cognitive processes, was raised ever since the early work of Gestalt psychologists. In the early 1980s, Treisman proposed the feature integration theory of attention (FIT), based on the findings of neuroscience. Soon after publishing her theory a new scientific approach appeared investigating several visual perception phenomena. The most widely researched were the key constru...

  14. Early diagnosis of breast cancer

    International Nuclear Information System (INIS)

    Semiglazov, V.F.

    1989-01-01

    Modern data are presentd on epidemology etiopathogensis and statistics of breast cancer. Home and international clinical and histological classifications is given. Much attention is paid to the methods for early diagnosis of pretumor diseases and breast cancer: clinical roentgenomammography, thrmography and computerized tomomammography. The role of self-examination in cancer early detection has been analyzed. Special attention is paid to system of detection of minimal and unpalpable form of breast cancer, screening of these tumors. 113 refs.; 60 figs.; 6 tabs

  15. Early presentation of primary glioblastoma.

    Science.gov (United States)

    Faguer, R; Tanguy, J-Y; Rousseau, A; Clavreul, A; Menei, P

    2014-08-01

    Clinical and neuroimaging findings of glioblastomas (GBM) at an early stage have rarely been described and those tumors are most probably under-diagnosed. Furthermore, their genetic alterations, to our knowledge, have never been previously reported. We report the clinical as well as neuroimaging findings of four early cases of patients with GBM. In our series, early stage GBM occurred at a mean age of 57 years. All patients had seizures as their first symptom. In all early stages, MRI showed a hyperintense signal on T2-weighted sequences and an enhancement on GdE-T1WI sequences. A hyperintense signal on diffusion sequences with a low ADC value was also found. These early observed occurrences of GBM developed rapidly and presented the MRI characteristics of classic GBM within a few weeks. The GBM size was multiplied by 32 in one month. Immunohistochemical analysis indicated the de novo nature of these tumors, i.e. absence of mutant IDH1 R132H protein expression, which is a diagnostic marker of low-grade diffuse glioma and secondary GBM. A better knowledge of early GBM presentation would allow a more suitable management of the patients and may improve their prognosis. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  16. [Autism: An early neurodevelopmental disorder].

    Science.gov (United States)

    Bonnet-Brilhault, F

    2017-04-01

    With approximately 67 million individuals affected worldwide, autism spectrum disorder (ASD) is the fastest growing neurodevelopmental disorder (United Nations, 2011), with a prevalence estimated to be 1/100. In France ASD affects approximately 600,000 individuals (from childhood to adulthood, half of whom are also mentally retarded), who thus have a major handicap in communication and in adapting to daily life, which leads autism to be recognized as a national public health priority. ASD is a neurodevelopmental disorder that affects several domains (i.e., socio-emotional, language, sensori-motor, executive functioning). These disorders are expressed early in life with an age of onset around 18 months. Despite evidence suggesting a strong genetic link with ASD, the genetic determinant remains unclear. The clinical picture is characterized by impairments in social interaction and communication and the presence of restrictive and repetitive behaviors (DSM-5, ICD-10). However, in addition to these two main dimensions there is significant comorbidity between ASD and other neurodevelopmental disorders such as attention deficit hyperactivity disorder or with genetic and medical conditions. One of the diagnostic features of ASD is its early emergence: symptoms must begin in early childhood for a diagnosis to be given. Due to brain plasticity, early interventions are essential to facilitate clinical improvement. Therefore, general practitioners and pediatricians are on the front line to detect early signs of ASD and to guide both medical explorations and early rehabilitation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. Early Learner Engagement in the Clinical Workplace

    NARCIS (Netherlands)

    Chen, H.C.

    2015-01-01

    Introduction Recent calls for medical education reform advocate for the integration of knowledge with clinical experience through early clinical immersion. Yet, early learners rarely are invited to participate in workplace activities and early clinical experiences remain largely observational.

  18. Foraminifera [Marine Microfossil] as an additional tool for archaeologists - Examples from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    or- ganisms, their presence and absence could be a deci- GLIMPSES OF MARINE ARCHAEOLOGY IN INDIA sive factor in interpreting whether any ancient water body was filled with fresh or marine (brackish) water. With this intention, the author has..., a conceptual model (Figure 4) was provided and techniques were developed for use of foraminifera as a proxy to determine the paleomonsoons. Studies on core samples off Karwar (Figure 5), west coast of India showed the clear signals of marked...

  19. Microfossil sequences in Ilponlampi, a small lake in northern Russian Karelia

    Directory of Open Access Journals (Sweden)

    Huttunen, A.

    1994-12-01

    Full Text Available The Holocene history of Ilponlampi, a small lake situated in northwestern Russian Karelia, is presented based on pollen, diatom, charred particle and botanical macroremain analyses. Four 14-C dates for the sequence show that it reaches back almost to the beginning of the Holocene. The immigration of the various tree species took place somewhat earlier than further west. A natural acidification process is characteristic of the lake, which seems to have remained practically unaffected by any human influence.

  20. Remarkable preservation of microfossils and biofilms in mesoproterozoic silicified bitumen concretions from Northern China

    DEFF Research Database (Denmark)

    Wang, Xiaomei; Zhang, Shuichang; Wang, Huajian

    2017-01-01

    Prokaryotes, often generally referred to as “bacteria,” are the original and thus oldest life on Earth. They have shaped the chemical environment of the Earth, but they are difficult to find as ancient fossils due to their subtle structure. Here we report well-preserved fossilized microbial...

  1. A neogene seawater sulfur isotope age curve from calcareous pelagic microfossils

    International Nuclear Information System (INIS)

    Burdett, J.W.; Arthur, M.A.; Richardson, M.

    1989-01-01

    Until now, our knowledge of the sulfur isotopic composition of seawater through geologic time has depended on stable isotopic analysis of sulfate from evaporites. Owing to the sporadic occurrence of evaporites through time, the secular sulfur isotope age curve contains many gaps with little or no data. In order to fill in some of these gaps, particularly the Neogene, we have analyzed the sulfur isotopic composition of carbonate-associated sulfate in carbonate tests of planktonic foraminifera. Other investigators have shown that sulfate may occur in biogenic calcites either lattice-bound, as micro-fluid inclusions, in adsorbed phases, or as protein polysaccharides. Whatever the origin, the sulfur isotopic composition of this sulfate appears to be representative of that of the water in which the organism lived, as shown by results on recent calcareous foraminifera and macrofossils. Using this approach for study of Miocene to Recent pelagic marine sediments supplemented by new data for Miocene marine evaporites from the Gulf of Suez, we have found that the δ 34 S of seawater has decreased about 2.5per mille over the past 25 m.y. and that most of the decrease has occurred over the past 5 m.y., paralleling a decrease in the δ 13 C of dissolved oceanic bicarbonate from the same interval. Sedimentary redox models based on isotope records suggest that organic carbon and sulfide burial have both decreased over the past 5 m.y. Alternatively, an increase in weathering rates over the past 5 m.y. would not require a decrease in organic carbon or sulfide burial as long as the isotopic effect of the increased river input exceeds the isotopic effect of the burial of the reduced species. In either case, the net result would be a decrease in atmospheric p O2 . (orig.)

  2. Gypsum-permineralized microfossils and their relevance to the search for life on Mars.

    Science.gov (United States)

    Schopf, J William; Farmer, Jack D; Foster, Ian S; Kudryavtsev, Anatoliy B; Gallardo, Victor A; Espinoza, Carola

    2012-07-01

    Orbital and in situ analyses establish that aerially extensive deposits of evaporitic sulfates, including gypsum, are present on the surface of Mars. Although comparable gypsiferous sediments on Earth have been largely ignored by paleontologists, we here report the finding of diverse fossil microscopic organisms permineralized in bottom-nucleated gypsums of seven deposits: two from the Permian (∼260 Ma) of New Mexico, USA; one from the Miocene (∼6 Ma) of Italy; and four from Recent lacustrine and saltern deposits of Australia, Mexico, and Peru. In addition to presenting the first report of the widespread occurrence of microscopic fossils in bottom-nucleated primary gypsum, we show the striking morphological similarity of the majority of the benthic filamentous fossils of these units to the microorganisms of a modern sulfuretum biocoenose. Based on such similarity, in morphology as well as habitat, these findings suggest that anaerobic sulfur-metabolizing microbial assemblages have changed relatively little over hundreds of millions of years. Their discovery as fossilized components of the seven gypsiferous units reported suggests that primary bottom-nucleated gypsum represents a promising target in the search for evidence of past life on Mars. Key Words: Confocal laser scanning microscopy-Gypsum fossils-Mars sample return missions-Raman spectroscopy-Sample Analysis at Mars (SAM) instrument-Sulfuretum.

  3. Search for supernova-produced {sup 60}Fe in the microfossil record

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Peter; Bishop, Shawn; Chernenko, Valentyna; Faestermann, Thomas; Famulok, Nicolai; Fimiani, Leticia; Gomez, Jose; Hain, Karin; Korschinek, Gunther [TU Muenchen, Physik Department (Germany); Egli, Ramon [ZAMG, Wien (Austria); Frederichs, Thomas [Universitaet Bremen, Geowissenschaften (Germany); Hanzlik, Marianne [TU Muenchen, Fakultaet fuer Chemie (Germany); Merchel, Silke; Rugel, Georg [HZDR, Dresden (Germany)

    2014-07-01

    Material distributed into the interstellar medium by supernova explosions can be incorporated into terrestrial archives. After the discovery of live {sup 60}Fe atoms in 2-3 Myr old layers of a Pacific Ocean ferromanganese crust, a confirmation of this signal, as well as a mapping of the signal with high time-resolution is desirable. Another reservoir in which the {sup 60}Fe signature should have been incorporated are the fossils of magnetotactic bacteria in ocean sediment. To this end, two sediment cores from the Eastern Equatorial Pacific were obtained, iron was chemically extracted with high selectivity towards biogenic magnetite, and the extraction procedure was characterized using novel magnetic measurements. The {sup 60}Fe/Fe concentration in the samples was then measured with accelerator mass spectrometry at the GAMS setup in Garching. Preliminary results for both sediment cores are reported.

  4. Neoproterozoic-Early Paleozoic Peri-Pacific Accretionary Evolution of the Mongolian Collage System: Insights From Geochemical and U-Pb Zircon Data From the Ordovician Sedimentary Wedge in the Mongolian Altai

    Science.gov (United States)

    Jiang, Y. D.; Schulmann, K.; Kröner, A.; Sun, M.; Lexa, O.; Janoušek, V.; Buriánek, D.; Yuan, C.; Hanžl, P.

    2017-11-01

    Neoproterozoic to early Paleozoic accretionary processes of the Central Asian Orogenic Belt have been evaluated so far mainly using the geology of ophiolites and/or magmatic arcs. Thus, the knowledge of the nature and evolution of associated sedimentary prisms remains fragmentary. We carried out an integrated geological, geochemical, and zircon U-Pb geochronological study on a giant Ordovician metasedimentary succession of the Mongolian Altai Mountains. This succession is characterized by dominant terrigenous components mixed with volcanogenic material. It is chemically immature, compositionally analogous to graywacke, and marked by significant input of felsic to intermediate arc components, pointing to an active continental margin depositional setting. Detrital zircon U-Pb ages suggest a source dominated by products of early Paleozoic magmatism prevailing during the Cambrian-Ordovician and culminating at circa 500 Ma. We propose that the Ordovician succession forms an "Altai sedimentary wedge," the evolution of which can be linked to the geodynamics of the margins of the Mongolian Precambrian Zavhan-Baydrag blocks. This involved subduction reversal from southward subduction of a passive continental margin (Early Cambrian) to the development of the "Ikh-Mongol Magmatic Arc System" and the giant Altai sedimentary wedge above a north dipping subduction zone (Late Cambrian-Ordovician). Such a dynamic process resembles the tectonic evolution of the peri-Pacific accretionary Terra Australis Orogen. A new model reconciling the Baikalian metamorphic belt along the southern Siberian Craton with peri-Pacific Altai accretionary systems fringing the Mongolian microcontinents is proposed to explain the Cambro-Ordovician geodynamic evolution of the Mongolian collage system.

  5. An unusual early Holocene diatom event north of the Getz Ice Shelf (Amundsen Sea): Implications for West Antarctic Ice Sheet development

    Science.gov (United States)

    Esper, O.; Gersonde, R.; Hillenbrand, C.; Kuhn, G.; Smith, J.

    2011-12-01

    Modern global change affects not only the polar north but also, and to increasing extent, the southern high latitudes, especially the Antarctic regions covered by the West Antarctic Ice Sheet (WAIS). Consequently, knowledge of the mechanisms controlling past WAIS dynamics and WAIS behaviour at the last deglaciation is critical to predict its development in a future warming world. Geological and palaeobiological information from major drainage areas of the WAIS, like the Amundsen Sea Embayment, shed light on the history of the WAIS glaciers. Sediment records obtained from a deep inner shelf basin north of Getz Ice Shelf document a deglacial warming in three phases. Above a glacial diamicton and a sediment package barren of microfossils that document sediment deposition by grounded ice and below an ice shelf or perennial sea ice cover (possibly fast ice), respectively, a sediment section with diatom assemblages dominated by sea ice taxa indicates ice shelf retreat and seasonal ice-free conditions. This conclusion is supported by diatom-based summer temperature reconstructions. The early retreat was followed by a phase, when exceptional diatom ooze was deposited around 12,500 cal. years B.P. [1]. Microscopical inspection of this ooze revealed excellent preservation of diatom frustules of the species Corethron pennatum together with vegetative Chaetoceros, thus an assemblage usually not preserved in the sedimentary record. Sediments succeeding this section contain diatom assemblages indicating rather constant Holocene cold water conditions with seasonal sea ice. The deposition of the diatom ooze can be related to changes in hydrographic conditions including strong advection of nutrients. However, sediment focussing in the partly steep inner shelf basins cannot be excluded as a factor enhancing the thickness of the ooze deposits. It is not only the presence of the diatom ooze but also the exceptional preservation and the species composition of the diatom assemblage

  6. Telomere lengthening early in development.

    Science.gov (United States)

    Liu, Lin; Bailey, Susan M; Okuka, Maja; Muñoz, Purificación; Li, Chao; Zhou, Lingjun; Wu, Chao; Czerwiec, Eva; Sandler, Laurel; Seyfang, Andreas; Blasco, Maria A; Keefe, David L

    2007-12-01

    Stem cells and cancer cells maintain telomere length mostly through telomerase. Telomerase activity is high in male germ line and stem cells, but is low or absent in mature oocytes and cleavage stage embryos, and then high again in blastocysts. How early embryos reset telomere length remains poorly understood. Here, we show that oocytes actually have shorter telomeres than somatic cells, but their telomeres lengthen remarkably during early cleavage development. Moreover, parthenogenetically activated oocytes also lengthen their telomeres, thus the capacity to elongate telomeres must reside within oocytes themselves. Notably, telomeres also elongate in the early cleavage embryos of telomerase-null mice, demonstrating that telomerase is unlikely to be responsible for the abrupt lengthening of telomeres in these cells. Coincident with telomere lengthening, extensive telomere sister-chromatid exchange (T-SCE) and colocalization of the DNA recombination proteins Rad50 and TRF1 were observed in early cleavage embryos. Both T-SCE and DNA recombination proteins decrease in blastocyst stage embryos, whereas telomerase activity increases and telomeres elongate only slowly. We suggest that telomeres lengthen during the early cleavage cycles following fertilization through a recombination-based mechanism, and that from the blastocyst stage onwards, telomerase only maintains the telomere length established by this alternative mechanism.

  7. Evaluation of early Archean volcaniclastic and volcanic flow rocks as possible sites for carbonaceous fossil microbes.

    Science.gov (United States)

    Walsh, Maud M

    2004-01-01

    Sedimentary rocks have traditionally been the focus of the search for Archean microfossils; the Earth's oldest fossil bacteria are associated with carbonaceous matter in sedimentary cherts in greenstone belts in the eastern Pilbara block of Western Australia and Barberton greenstone belt of South Africa. Reports of possible fossils in a martian meteorite composed of igneous rock and the discovery of modern bacteria associated with basalts have stimulated a new look at Archean volcanic rocks as possible sites for fossil microbes. This study examines silicified volcaniclastic rocks, near-surface altered volcanic flow rocks, and associated stromatolite- like structures from the Archean Barberton greenstone belt to evaluate their potential for the preservation of carbonaceous fossils. Detrital carbonaceous particles are widely admixed with current-deposited debris. Carbonaceous matter is also present in altered volcanic flow rocks as sparse particles in silica veins that appear to be fed by overlying carbonaceous chert layers. Neither microfossils nor mat-like material was identified in the altered volcanic rocks or adjacent stromatolite-like structures. Ancient volcanic flow and volcaniclastic rocks are not promising sites for carbonaceous fossil preservation.

  8. Routine Early Angioplasty after Fibrinolysis

    DEFF Research Database (Denmark)

    Wang, Zhipeng; Liang, Bo; Mei, Qibing

    2009-01-01

    patients in the group that underwent routine early PCI than in the group that received standard treatment received clopidogrel (Ppatients who undergo PCI, as well as in those who do not, is well established,1...... with early beta-blocker therapy is taken into consideration.3 The overall benefit of clopidogrel and beta-blocker therapy could have influenced the outcome in patients who underwent early PCI. These facts leave the conclusion of the TRANSFER-AMI trial still highly uncertain.......To the Editor: Cantor et al. report that there is a significantly reduced rate of ischemic complications among patients with myocardial infarction with ST-segment elevation who are transferred for PCI within 6 hours after fibrinolysis. However, Table 2 of the article shows that significantly more...

  9. Brachytherapy in early prostate cancer--early experience.

    Science.gov (United States)

    Jose, B O; Bailen, J L; Albrink, F H; Steinbock, G S; Cornett, M S; Benson, D C; Schmied, W K; Medley, R N; Spanos, W J; Paris, K J; Koerner, P D; Gatenby, R A; Wilson, D L; Meyer, R

    1999-01-01

    Use of brachytherapy with radioactive seeds in the management of early prostate cancer is commonly used in the United States. The early experience has been reported from the prostate treatment centers in Seattle for the last 10 years. In this manuscript we are reporting our early experience of 150 radioactive seed implantations in early stage prostate cancer using either Iodine 125 or Palladium 103 seeds. The average age of the patient is 66 years and the median Gleason score is 5.4 with a median PSA of 6. A brief description of the evolution of the treatment of prostate cancer as well as the preparation for the seed implantation using the volume study with ultrasound of the prostate, pubic arch study using CT scan of the pelvis and the complete planning using the treatment planning computers are discussed. We also have described the current technique which is used in our experience based on the Seattle guidelines. We plan a follow-up report with the results of the studies with longer follow-up.

  10. Early diagnosis of lung cancer

    International Nuclear Information System (INIS)

    Scherrer, M.

    1982-01-01

    Unanimity does not exist about the utility and organisation of screening procedures for early diagnosis of lung cancer. We describe a low cost structue of screening, requiring only a minimum of compliance from the elderly smoker and ex-smoker. At 4 months interval, radiographs, sputum cytologies and eventual fiberbronchoscopies are realized in all that elderly smokers and ex-smokers which begin to present one of the first early lung cancer signs or symptoms (loss of weight, hemoptoe, thoracic pain and others). (orig.) [de

  11. Shocks in the Early Universe.

    Science.gov (United States)

    Pen, Ue-Li; Turok, Neil

    2016-09-23

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVUniverse as early as 10^{-30}  sec after the big bang.

  12. Paleo-environment in the upper amazon basin during early to middle Miocene times

    Science.gov (United States)

    van Soelen, Els; Hoorn, Carina; Santos, Roberto V.; Dantas, Elton L.; Sinninghe Damsté, Jaap S.; Kim, Jung-Hyun

    2014-05-01

    The Amazon River has the largest catchment in the world and is responsible for the largest water discharge from land to the ocean. The river system that flows from the Andes to the Atlantic Equatorial Margin exists since the late Miocene, and results from Andean uplift which strongly affected erosion/deposition and major flow patterns in northern South-America. Two outcrop sites from the Solimões basin, Mariñame (17.7-16.1 Ma) and Los Chorros (14.2-12.7 Ma), may shed light on the inland paleo-environmental conditions during a period of active Andean uplift in the early to middle Miocene. Earlier works revealed the Mariñame outcrops to represent a river born in Amazonia. Instead the Los Chorros outcrops are relics of the Amazon River system, characterized by extensive wetlands consisting of swamps, shallow lakes, crevasse splays channels and crevasse-delta lakes (e.g. Hoorn et al., 2010). The freshwater ecosystems alternate with some intervals that are rich in marine palynomorphs (such as dinocysts), mangrove pollen, brackish tolerant molluscs and ostracods, which indicate brackish conditions and a marine influence. It is thought that these marine incursion are related to phases of global sea-level rise and rapid subsidence in the Andean foreland (Marshall & Lundberg, 1996). Still, much remains unknown about the Miocene river systems, like the extent and diversity of the wetland system and the nature of the marine incursions. To get a better understanding of the sources of the (in)organic material, geochemical methods were used. Strontium (Sr) and Neodymium (Nd) isotopes were analyzed on bulk sediments, and used for a paleo-provenance study. The Sr and Nd isotopic signature in the older section (Mariñame) is in general more radiogenic compared to the Los Chorros section. The most radiogenic values are comparable to those found nowadays in the the Precambrian Guyana shield. A Guyana sediment source would suggest a distinctly different flow direction of the major

  13. Early-delayed radiation rhombencephalopathy

    International Nuclear Information System (INIS)

    Nightingale, S.; Dawes, P.J.D.K.; Cartlidge, N.E.F.; Newcastle upon Tyne Univ.

    1982-01-01

    A 37-year-old woman developed an early-delayed rhombencephalopathy 7 weeks after completing a course of radiotherapy to a glomus jugulare tumour. The clinical features, comprising nystagmus, skew strabismus, unilateral facial weakness, dysarthria and ataxia, are compared with four previously reported patients with this syndrome. (author)

  14. Early stage fuel cell funding

    International Nuclear Information System (INIS)

    Bergeron, C.

    2004-01-01

    'Full text:' Early stage venture funding requires an in depth understanding of both current and future markets as well as the key technical hurdles that need to be overcome for new technology to commercialize into successful products for mass markets. As the leading fuel cell and hydrogen investor, Chrysalix continuously reviews global trends and new technologies, evaluates them with industry leaders worldwide and tries to match them up with the best possible management teams when selecting its early stage investments. Chrysalix Energy Limited Partnership is an early-stage venture capital firm focusing on fuel cell and related fueling technology companies and is a private equity joint venture between Ballard Power Systems, BASF Venture Capital, The BOC Group, The Boeing Company, Duke Energy, Mitsubishi Corporation and Shell Hydrogen. Operating independently, Chrysalix offers a unique value proposition to its clients throughout the business planning, start-up and operations phases of development. Chrysalix provides early-stage funding to new companies as well as management assistance, technological knowledge, organized networking with industry players and experience in the management of intellectual property. (author)

  15. Early Childhood Intervention in China

    Science.gov (United States)

    Zheng, Yuzhu; Maude, Susan P.; Brotherson, Mary Jane

    2015-01-01

    With rapid economic development and increasing awareness of the importance of early childhood intervention (ECI), China is re-examining its social and educational practices for young children with disabilities. This re-examination may have a significant impact on young children with disabilities in China. It may also set an example for other…

  16. Uganda Early Generation Seed Study

    NARCIS (Netherlands)

    Mastenbroek, A.; Ntare, Bonny

    2016-01-01

    One of the major bottlenecks limiting farmers’ access to good quality seed for food crops in Uganda is the shortage of early generation seed (EGS - breeder and foundation) to produce sufficient quantities of certified and/or quality declared) to satisfy the needs of farmers. A national study was

  17. Early and Late Retirement Exits

    Science.gov (United States)

    Brougham, Ruby R.; Walsh, David A.

    2009-01-01

    The current study proposes that personal need fulfillment (relatedness, generativity, identity, growth, and finances) predicts early and late retirement intentions. The personal needs of 160 full-time older employees were measured by personal goals, job satisfactions, job characteristics, and intrinsic motivation. Results suggest that the personal…

  18. Defeating cancer with early detection

    CERN Document Server

    2003-01-01

    A meeting of scientists and industry experts will hold an open review of the Three Dimension Complete Body Screening System (3D-CBS) on the 1st of July 2003. This new imaging technlogy is potentially powerful and safe enough to offer routine screening of healthy patients for early signs of cancer (1 page).

  19. Boys' Bodies in Early Childhood

    Science.gov (United States)

    Drummond, Murray

    2012-01-01

    This paper is based on qualitative research data from a project investigating early childhood boys' constructions of masculinities in relation to sport, health and the body. The focus group data, with 33 boys, has been collected in each of the boys' first three years at school. It is part of the data that will be collected over eight years with…

  20. Early Childhood Inclusion in Croatia

    Science.gov (United States)

    Ljubešic, Marta; Šimleša, Sanja

    2016-01-01

    This article explains early childhood inclusion in Croatia from its beginnings up to challenges in current policy and practice. The first preschool education for children with disabilities dates back to the 1980s and was provided in special institutions. In the last 10 years, mainstream kindergartens have been enrolling children with disabilities…

  1. Early Childhood Education in Scandinavia.

    Science.gov (United States)

    Austin, Gilbert R.; Dittman, Laura

    This article discusses the move toward greater equality of educational opportunity in Scandinavia with particular emphasis on early childhood education. The increasing demand for preschool education in Denmark, Finland, Norway and Sweden is related to low birth rates together with increased employment of women and the general demand for equality…

  2. Galaxies in the Early Universe

    DEFF Research Database (Denmark)

    Krogager, Jens-Kristian

    Understanding how galaxies evolved from the early Universe through cosmic time is a fundamental part of modern astrophysics. In order to study this evolution it is important to sample the galaxies at various times in a consistent way through time. In regular luminosity selected samples, our...

  3. Glucocorticoids in early rheumatoid arthritis

    NARCIS (Netherlands)

    Everdingen, Amalia A. van

    2002-01-01

    For 50 years, glucocorticoids (GC) are used for symptomatic treatment of rheumatoid arthritis (RA). In the last decade, results from clinical studies of treatment with GC as additional therapy to long-acting antirheumatic drugs in patients with early RA suggested also disease-modifying properties of

  4. Internationalism in Early Adult Education.

    Science.gov (United States)

    Keane, Patrick

    1985-01-01

    Explores the nature and scope of internationalism in early 19th century adult education, using as a context the lyceums and mechanics' institutes of Britain and North America. The contacts involved newspaper and journal accounts, the personal advocacy of former members, written advice from promoters and administrators, and the contributions of…

  5. Management of early pregnancy loss

    NARCIS (Netherlands)

    Graziosi, G. C. M.; Mol, B. W.; Ankum, W. M.; Bruinse, H. W.

    2004-01-01

    Objectives: In order to assess the available evidence on the management of early pregnancy loss, we performed a meta-analysis on the subject. Methods: MEDLINE and EMBASE were searched for randomized studies reporting on the effectiveness of expectant management, misoprostol treatment or curettage.

  6. Physics of the early universe

    International Nuclear Information System (INIS)

    Klinkhamer, F.R.

    1983-01-01

    In this thesis, the author has assembled his papers on elementary particle physics which are of importance for studying cosmology viz. the physics of the early universe. A rather detailed introduction reviewing basic principles and current trends in the relation particle physics/cosmology precedes the papers. (Auth.)

  7. Electromigration early resistance increase measurements

    NARCIS (Netherlands)

    Niehof, J.; Flinn, P.A.; Maloney, T.J.

    1993-01-01

    An early resistance change measurement set-up, using an AC bridge technique, has been developed, and measurements have been performed. Large sample-to-sample variations occur. The characteristic time for the resistance change curve is shorter for resistance increase (under current stress) than for

  8. Early Learning Theories Made Visible

    Science.gov (United States)

    Beloglovsky, Miriam; Daly, Lisa

    2015-01-01

    Go beyond reading about early learning theories and see what they look like in action in modern programs and teacher practices. With classroom vignettes and colorful photographs, this book makes the works of Jean Piaget, Erik Erikson, Lev Vygotsky, Abraham Maslow, John Dewey, Howard Gardner, and Louise Derman-Sparks visible, accessible, and easier…

  9. Early Diagnosis of Breast Cancer.

    Science.gov (United States)

    Wang, Lulu

    2017-07-05

    Early-stage cancer detection could reduce breast cancer death rates significantly in the long-term. The most critical point for best prognosis is to identify early-stage cancer cells. Investigators have studied many breast diagnostic approaches, including mammography, magnetic resonance imaging, ultrasound, computerized tomography, positron emission tomography and biopsy. However, these techniques have some limitations such as being expensive, time consuming and not suitable for young women. Developing a high-sensitive and rapid early-stage breast cancer diagnostic method is urgent. In recent years, investigators have paid their attention in the development of biosensors to detect breast cancer using different biomarkers. Apart from biosensors and biomarkers, microwave imaging techniques have also been intensely studied as a promising diagnostic tool for rapid and cost-effective early-stage breast cancer detection. This paper aims to provide an overview on recent important achievements in breast screening methods (particularly on microwave imaging) and breast biomarkers along with biosensors for rapidly diagnosing breast cancer.

  10. Early Signs of Entrepreneurial Giftedness

    Science.gov (United States)

    Shavinina, Larisa V.

    2008-01-01

    Although successful entrepreneurship is important for the economic prosperity of any society, one should acknowledge that entrepreneurial giftedness is terra incognita from a research viewpoint. This article analyzes early manifestations of entrepreneurial giftedness in the cases of Richard Branson, Michael Dell, and Bill Gates and thus opens a…

  11. FUNdamental Movement in Early Childhood.

    Science.gov (United States)

    Campbell, Linley

    2001-01-01

    Noting that the development of fundamental movement skills is basic to children's motor development, this booklet provides a guide for early childhood educators in planning movement experiences for children between 4 and 8 years. The booklet introduces a wide variety of appropriate practices to promote movement skill acquisition and increased…

  12. IDEA and Early Childhood Inclusion.

    Science.gov (United States)

    Smith, Barbara J.; Rapport, Mary Jane K.

    This paper discusses 1997 amendments to the Individuals with Disabilities Education Act (IDEA) that promote the inclusion of children with disabilities in general early childhood education settings. The evolution of inclusion policy is explored and changes in disability terminology are described. Amended provisions are then explained and include:…

  13. Melanoma early detection and awareness

    DEFF Research Database (Denmark)

    Wainstein, Alberto; Algarra, Salvador Martin; Bastholt, Lars

    2014-01-01

    to increase public awareness and favor early diagnosis. Awareness campaigns, doctor education, and screening of high-risk subjects have all contributed to improve disease outcome in developed countries. The role of primary care physicians is particularly relevant in this regard. Developing countries...

  14. Early Childhood Inclusion in Israel

    Science.gov (United States)

    Al-Yagon, Michal; Aram, Dorit; Margalit, Malka

    2016-01-01

    This article describes conceptual aspects, current policies and practices, and research representing the Israeli perspective regarding early childhood inclusion (ECI) at preschool ages (3-6 years). We review legislative, historical, attitudinal, philosophical, practical, empirical, and cultural issues regarding ECI in Israel. Finally, we focus on…

  15. Reduplication Facilitates Early Word Segmentation

    Science.gov (United States)

    Ota, Mitsuhiko; Skarabela, Barbora

    2018-01-01

    This study explores the possibility that early word segmentation is aided by infants' tendency to segment words with repeated syllables ("reduplication"). Twenty-four nine-month-olds were familiarized with passages containing one novel reduplicated word and one novel non-reduplicated word. Their central fixation times in response to…

  16. Early Childhood Inclusion in Australia

    Science.gov (United States)

    Kemp, Coral R.

    2016-01-01

    From the introduction of early intervention services in Australian in the mid-1970s, the families of children with intellectual and multiple disabilities have been encouraged to enroll their children in local preschools and childcare centers. Children with disabilities have also accessed a range of alternatives to full inclusion, such as reverse…

  17. HPLC: Early and Recent Perspectives.

    Science.gov (United States)

    Karger, Barry L.

    1997-01-01

    Provides a perspective on what it was like in the early days of high-performance liquid chromatography (HPLC) and several of the key developments. Focuses on the advances in HPLC generally, and more specifically for the biological sciences, that were necessary for the method to reach the preeminent stage of today. Contains 20 references. (JRH)

  18. Early Children's Literature and Aging

    Science.gov (United States)

    McGuire, Sandra L.

    2016-01-01

    Increased longevity is a worldwide phenomenon placing emphasis on the need for preparation for life's later years. Today's children will be the older adults of tomorrow. A resource that can help to educate them about aging and prepare them for the long life ahead is early children's literature (Preschool-Primary). This literature can provide…

  19. Vantage point - Early warning flaws.

    Science.gov (United States)

    Swinden, Donna

    2014-08-28

    USING AN EARLY warning score (EWS) system should improve the detection of acutely deteriorating patients. Under such a system, a score is allocated to each of six physiological measurements including respiratory rate and oxygen saturations, which are aggregated to produce an overall score. An aggregated score of seven or higher prompts nursing staff to refer a patient for emergency assessment.

  20. The Integrated Early Childhood Curriculum.

    Science.gov (United States)

    Krogh, Suzanne

    This textbook provides an outline of an integrated curriculum for early childhood education. Part 1 discusses the human element in school: the child and the teacher and child development. Part 2 contains the curriculum itself and covers the subjects of language, mathematics, science, social studies, art, music, and movement. Guidelines provide…

  1. Natural course of early COPD

    Directory of Open Access Journals (Sweden)

    Rhee CK

    2017-02-01

    Full Text Available Chin Kook Rhee,1 Kyungjoo Kim,1 Hyoung Kyu Yoon,2 Jee-Ae Kim,3 Sang Hyun Kim,4 Sang Haak Lee,5 Yong Bum Park,6 Ki-Suck Jung,7 Kwang Ha Yoo,8 Yong Il Hwang7 1Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Seoul St Mary’s Hospital, 2Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Yeouido St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, 3Pharmaceutical Policy Evaluation Research Team, Research Institution, 4Big Data Division, Health Insurance Review and Assessment Service, Wonju, 5Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, St Paul’s Hospital, College of Medicine, The Catholic University of Korea, 6Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, 7Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, 8Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Republic of Korea Background and objective: Few studies have examined the natural course of early COPD. The aim of this study was to observe the natural course of early COPD patients. We also aimed to analyze medical utilization and costs for early COPD during a 6-year period. Methods: Patients with early COPD were selected from Korean National Health and Nutrition Examination Survey (KNHANES data. We linked the KNHANES data of patients with early COPD to National Health Insurance data. Results: A total of 2,397 patients were enrolled between 2007 and 2012. The mean forced expiratory volume in 1 second (FEV1 was 78.6%, and the EuroQol five dimensions questionnaire (EQ-5D index value was 0.9. In total, 110 patients utilized health

  2. Blueschist facies fault tectonites from the western margin of the Siberian Craton: Implications for subduction and exhumation associated with early stages of the Paleo-Asian Ocean

    Science.gov (United States)

    Likhanov, Igor I.; Régnier, Jean-Luc; Santosh, M.

    2018-04-01

    The tectonic evolution of the Siberian Cratonic margins offers important clues for global paleogeographic reconstructions, particularly with regard to the complex geological history of Central Asia. The Yenisey Ridge fold-and-thrust belt at the western margin of the Siberian Craton forms part of the Central Asian Orogenic Belt (CAOB) and is a key to understand the Precambrian tectonic evolution of the Siberian Craton and crustal growth in the CAOB, the world's largest Phanerozoic accretionary orogenic belt. Here we report for the first time, the occurrence of glaucophane schist relics in tectonites within the Yenisey shear zone which provides insights on Chilean-type convergent boundary. We present results from isotope geochronology (SHRIMP zircon analysis and mica 40Ar/39Ar dating), coupled with P-T calculations derived from conventional geothermobarometry and pseudosections in the system NCKFMASH that suggest two superimposed metamorphic events. During the first stage, glaucophane schists formed at around 640-620 Ma at P-T conditions of 8-10 kbar and 400-450 °C. In the second stage, the rocks experienced dynamic metamorphism (c. 600 Ma) at 11-15 kbar/550-640 °C. The differences in P-T parameters between weakly deformed rocks and intensely deformed tectonites and P-T paths suggest distinct tectonic processes. Geochemical features of the mafic tectonites suggest N-MORB and E-MORB affinity, and the zircon U-Pb ages suggest formation of the protoliths at 701.6 ± 8.4. The sequence of spreading, subduction and shear deformation identified in our study correlate with the early stages of development of the Paleo-Asian Ocean at the western margin of the Siberian Craton and supports the spatial proximity of Siberia and Laurentia at 700-600 Ma, as proposed for the Late Neoproterozoic paleogeographic reconstructions and as robustly constrained from large igneous province (LIP) record.

  3. Evidence of early Archean crust in northwest Gondwana, from U-Pb and Hf isotope analysis of detrital zircon, in Ediacaran surpacrustal rocks of northern Spain

    Science.gov (United States)

    Naidoo, Thanusha; Zimmermann, Udo; Vervoort, Jeff; Tait, Jenny

    2018-03-01

    The Mora Formation (Narcea Group) is one of the oldest Precambrian supracrustal successions in northern Spain. Here, we use U-Pb and in situ Hf isotope analysis on detrital zircon to determine its age and provenance. The youngest U-Pb dates constrain the maximum depositional age of the Mora Formation at 565 ± 11 Ma. Results indicate: (1) a dominant Ediacaran zircon population (33%; 565-633 Ma, Cadomian) within a spectrum of Neoproterozoic ages (40%; 636-996 Ma); and (2) smaller Mesoproterozoic (5%; 1004-1240 Ma), Palaeoproterozoic (11%; 1890-2476 Ma) and Archean (11%; 2519-3550 Ma) populations. Results here do not point to one specific cratonic source area; instead, detritus may have been derived from the West African craton and Amazonia, or even the concealed Iberian basement. The lack of 1.3-1.8 Ga grains suggests exclusion of the Sahara Craton as a major source, but this is not certain. This mixed composition favours a complex source history with reworking of detritus across terrane/craton boundaries. Hafnium isotope compositions indicate a range of crustal and juvenile sources, with initial ɛHf values between -15.8 and 11.1, and Hf model ages from 0.8 to 3.7 Ga. For Neoproterozoic zircons (80%), juvenile components (ɛHf(i) +10) may be related to Rodinia fragmentation and the onset of an active margin setting leading to the Cadomian orogeny. Palaeoproterozoic to Paleoarchean grains (20%) all have negative ɛHf values and Meso- to Eoarchean Hf model ages. This indicates an early (Archean) sialic crustal component for northwestern Gondwana.

  4. The Skeleton Forming Proteome of an Early Branching Metazoan: A Molecular Survey of the Biomineralization Components Employed by the Coralline Sponge Vaceletia Sp.

    Directory of Open Access Journals (Sweden)

    Juliane Germer

    Full Text Available The ability to construct a mineralized skeleton was a major innovation for the Metazoa during their evolution in the late Precambrian/early Cambrian. Porifera (sponges hold an informative position for efforts aimed at unraveling the origins of this ability because they are widely regarded to be the earliest branching metazoans, and are among the first multi-cellular animals to display the ability to biomineralize in the fossil record. Very few biomineralization associated proteins have been identified in sponges so far, with no transcriptome or proteome scale surveys yet available. In order to understand what genetic repertoire may have been present in the last common ancestor of the Metazoa (LCAM, and that may have contributed to the evolution of the ability to biocalcify, we have studied the skeletal proteome of the coralline demosponge Vaceletia sp. and compare this to other metazoan biomineralizing proteomes. We bring some spatial resolution to this analysis by dividing Vaceletia's aragonitic calcium carbonate skeleton into "head" and "stalk" regions. With our approach we were able to identify 40 proteins from both the head and stalk regions, with many of these sharing some similarity to previously identified gene products from other organisms. Among these proteins are known biomineralization compounds, such as carbonic anhydrase, spherulin, extracellular matrix proteins and very acidic proteins. This report provides the first proteome scale analysis of a calcified poriferan skeletal proteome, and its composition clearly demonstrates that the LCAM contributed several key enzymes and matrix proteins to its descendants that supported the metazoan ability to biocalcify. However, lineage specific evolution is also likely to have contributed significantly to the ability of disparate metazoan lineages to biocalcify.

  5. Famines in Africa: is early warning early enough?

    Directory of Open Access Journals (Sweden)

    Jeeyon Janet Kim

    2012-06-01

    Full Text Available Following the second Sahelian famine in 1984–1985, major investments were made to establish Early Warning Systems. These systems help to ensure that timely warnings and vulnerability information are available to decision makers to anticipate and avert food crises. In the recent crisis in the Horn of Africa, alarming levels of acute malnutrition were documented from March 2010, and by August 2010, an impending food crisis was forecast. Despite these measures, the situation remained unrecognised, and further deteriorated causing malnutrition levels to grow in severity and scope. By the time the United Nations officially declared famine on 20 July 2011, and the humanitarian community sluggishly went into response mode, levels of malnutrition and mortality exceeded catastrophic levels. At this time, an estimated 11 million people were in desperate and immediate need for food. With warnings of food crises in the Sahel, South Sudan, and forecast of the drought returning to the Horn, there is an immediate need to institutionalize change in the health response during humanitarian emergencies. Early warning systems are only effective if they trigger an early response.

  6. Pompe Disease: Early Diagnosis and Early Treatment Make a Difference

    Directory of Open Access Journals (Sweden)

    Yin-Hsiu Chien

    2013-08-01

    Full Text Available Pompe disease (glycogen storage disease type II or acid maltase deficiency is a lysosomal disorder in which acid α-glucosidase (GAA deficiencies lead to intralysosomal accumulation of glycogen in all tissues; most notably in skeletal muscles. Both the patient's age at the onset of Pompe disease symptoms and the rate of deterioration caused by the disease can vary considerably. In classical infant-onset Pompe disease (IOPD, symptoms start very early in life, and death occurs soon afterward if the disease remains untreated. In later-onset Pompe disease, symptoms are slower to appear, and patients often progress to wheelchair confinement and eventual respiratory failure. A diagnosis can be made by screening for GAA in dried blood samples, followed either by GAA assessment in lymphocytes or in fibroblasts or by the genetic analysis of mutations. Treatment by enzyme replacement therapy (ERT with alglucosidase alfa was approved for human use in 2006. In classical IOPD, treatment significantly lengthens survival and improves motor development and cardiac function. The sooner ERT begins, the better are the results. Newborn screening aims to take advantage of different technologies for diagnosing and treating newborns early on and it yields better outcomes. However, newborns diagnosed early and other long-term survivors may encounter fresh problems, making up a new phenotype of IOPD patients. Further modifications of the treatment, such as a decrease in immune responses to ERT, a higher dosage, a better uptake formulation, and gene therapy delivered locally or systemically are being explored.

  7. Abnormal early cleavage events predict early embryo demise: sperm oxidative stress and early abnormal cleavage.

    Science.gov (United States)

    Burruel, Victoria; Klooster, Katie; Barker, Christopher M; Pera, Renee Reijo; Meyers, Stuart

    2014-10-13

    Human embryos resulting from abnormal early cleavage can result in aneuploidy and failure to develop normally to the blastocyst stage. The nature of paternal influence on early embryo development has not been directly demonstrated although many studies have suggested effects from spermatozoal chromatin packaging, DNA damage, centriolar and mitotic spindle integrity, and plasma membrane integrity. The goal of this study was to determine whether early developmental events were affected by oxidative damage to the fertilizing sperm. Survival analysis was used to compare patterns of blastocyst formation based on P2 duration. Kaplan-Meier survival curves demonstrate that relatively few embryos with short (P2 times reached blastocysts, and the two curves diverged beginning on day 4, with nearly all of the embryos with longer P2 times reaching blastocysts by day 6 (p < .01). We determined that duration of the 2nd to 3rd mitoses were sensitive periods in the presence of spermatozoal oxidative stress. Embryos that displayed either too long or too short cytokineses demonstrated an increased failure to reach blastocyst stage and therefore survive for further development. Although paternal-derived gene expression occurs later in development, this study suggests a specific role in early mitosis that is highly influenced by paternal factors.

  8. Giving the early fossil record of sponges a squeeze.

    Science.gov (United States)

    Antcliffe, Jonathan B; Callow, Richard H T; Brasier, Martin D

    2014-11-01

    Twenty candidate fossils with claim to be the oldest representative of the Phylum Porifera have been re-analysed. Three criteria are used to assess each candidate: (i) the diagnostic criteria needed to categorize sponges in the fossil record; (ii) the presence, or absence, of such diagnostic features in the putative poriferan fossils; and (iii) the age constraints for the candidate fossils. All three criteria are critical to the correct interpretation of any fossil and its placement within an evolutionary context. Our analysis shows that no Precambrian fossil candidate yet satisfies all three of these criteria to be a reliable sponge fossil. The oldest widely accepted candidate, Mongolian silica hexacts from c. 545 million years ago (Ma), are here shown to be cruciform arsenopyrite crystals. The oldest reliable sponge remains are siliceous spicules from the basal Cambrian (Protohertzina anabarica Zone) Soltanieh Formation, Iran, which are described and analysed here in detail for the first time. Extensive archaeocyathan sponge reefs emerge and radiate as late as the middle of the Fortunian Stage of the Cambrian and demonstrate a gradual assembly of their skeletal structure through this time coincident with the evolution of other metazoan groups. Since the Porifera are basal in the Metazoa, their presence within the late Proterozoic has been widely anticipated. Molecular clock calibration for the earliest Porifera and Metazoa should now be based on the Iranian hexactinellid material dated to c. 535 Ma. The earliest convincing fossil sponge remains appeared at around the time of the Precambrian-Cambrian boundary, associated with the great radiation events of that interval. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  9. Do schizophrenia patients age early?

    Science.gov (United States)

    Shivakumar, Venkataram; Kalmady, Sunil V; Venkatasubramanian, Ganesan; Ravi, Vasanthapuram; Gangadhar, Bangalore N

    2014-08-01

    The etiopathogenesis of schizophrenia is poorly understood. Within the proposed "neurodegeneration paradigm", observations have been put forth for "accelerated aging" in this disorder. This proposition is largely based on the neuroscience research that demonstrates progressive changes in brain as well as other systemic abnormalities supportive of faster aging process in patients with this disorder. In this review, we have summarized the literature related to the concept of early aging in schizophrenia. These studies include P300 abnormalities & visual motion discrimination, neuroimaging findings, telomere dynamics as well as neuropathology of related brain regions. We also propose a role of vitamin D, neuroimmunological changes and elevated oxidative stress as well as mitochondrial dysfunction in addition to the above factors with 'vitamin-D deficiency' as the central paradox. Put together, the evidence supporting early aging in schizophrenia is compelling and this requires further systematic studies. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Nanotechnology for Early Cancer Detection

    Directory of Open Access Journals (Sweden)

    Joon Won Park

    2010-01-01

    Full Text Available Vast numbers of studies and developments in the nanotechnology area have been conducted and many nanomaterials have been utilized to detect cancers at early stages. Nanomaterials have unique physical, optical and electrical properties that have proven to be very useful in sensing. Quantum dots, gold nanoparticles, magnetic nanoparticles, carbon nanotubes, gold nanowires and many other materials have been developed over the years, alongside the discovery of a wide range of biomarkers to lower the detection limit of cancer biomarkers. Proteins, antibody fragments, DNA fragments, and RNA fragments are the base of cancer biomarkers and have been used as targets in cancer detection and monitoring. It is highly anticipated that in the near future, we might be able to detect cancer at a very early stage, providing a much higher chance of treatment.

  11. Early intervention services in psychosis

    DEFF Research Database (Denmark)

    Csillag, Claudio; Nordentoft, Merete; Mizuno, Masafumi

    2016-01-01

    AIM: Early intervention (EI) in psychosis is a comprehensive and evidence-based approach aimed at detection and treatment of psychotic symptoms in their early stages. This paper presents core features and noteworthy aspects of the evidence basis and limitations of EI, the importance of programme ....... Wider dissemination of EI services will probably benefit from better integration of potential funders, promotion of joint targets and shared financial or budgetary incentives....... overcome these difficulties. CONCLUSIONS: Funding for mental health in general and for EI services appears low relative to need. One key argument for better funding for EI can be found in its favourable cost-effectiveness, but not all stakeholders beyond mental health administrators are aware of this...

  12. Cosmology and the early universe

    CERN Document Server

    Di Bari, Pasquale

    2018-01-01

    This book discusses cosmology from both an observational and a strong theoretical perspective. The first part focuses on gravitation, notably the expansion of the universe and determination of cosmological parameters, before moving onto the main emphasis of the book, the physics of the early universe, and the connections between cosmological models and particle physics. Readers will gain a comprehensive account of cosmology and the latest observational results, without requiring prior knowledge of relativistic theories, making the text ideal for students.

  13. Early laparotomy after lung transplantation

    DEFF Research Database (Denmark)

    Bredahl, Pia; Zemtsovski, Mikhail; Perch, Michael

    2014-01-01

    BACKGROUND: Gastrointestinal complications after lung transplantation have been reported with incidence rates ranging from 3% to 51%, but the reasons are poorly understood. We aimed to investigate the correlations between pulmonary diseases leading to lung transplantation and early gastrointestinal...... for time on mechanical ventilation. Among pulmonary diseases and demographics of the patients, no other risk factors were identified for laparotomy. CONCLUSIONS: A1AD was the only significant risk factor identified for gastrointestinal complications that required laparotomy within 3 months after lung...

  14. The early days of incineration

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, M.

    1995-05-01

    Landfills reaching capacity, beaches fouled with trash, neighborhood residents protesting waste disposal sites in their backyards, and municipalities forced to recycle. Sound familiar? These issues might have been taken from today`s headlines, but they were also problems facing mechanical engineers a century ago. Conditions such as these were what led engineers to design the first incinerators for reducing the volume of municipal garbage, as well as for producing heat and electricity. The paper discusses these early days.

  15. Interpersonal relationships in early adulthood

    OpenAIRE

    Kočevar, Zala

    2014-01-01

    Interpersonal relationships in early adulthood, in people aged 25 to 30 vary considerably among individuals. Some place emphasis on partnership, and others on relations with friends. Even the relationship with parents and siblings are experienced by young adults in a variety of ways. Some have frequent and regular contact with their parents while some no longer have any relationship with their parents. These are two frequent situations hiding much more in between. Relationships are complex an...

  16. Supporting Families through Early Intervention

    Directory of Open Access Journals (Sweden)

    Roy McConkey

    2003-09-01

    Full Text Available Internationally early intervention programmes for infants and preschoolers with disabilities have proved to be remarkably successful. In many countries, they began with teachers for visually impaired or hearing impaired children visiting the family home to teach parents how they could overcome the child's impairments. The logic of early intervention was inequitable. For example, the sooner children with visual impairments learnt to be independently mobile, then the greater their potential to learn and to kad an ordinary life. In time, this philosophy was extended to children with neurological and developmental delays, such as mental retardation, although success could be variable. In part, many different factors contributed to this variability: the form the interventions took, the extent of family involvement in the intervention and the lack of sensitivity of the measures used to assess a child's progress, to name but three. Perhaps the most extensive and intensive Early intervention schemes have been in the United States with their Head Start programmes. They were aimed at promoting the educational potential of preschoolers from deprived socio - economic backgrounds. Although the first phase of programmes had varying success, those in the second phase yielded impressive results which were mainly attributed to a greater focus on parental participation and links forged with the school system. Recently in developing countries, priority has been given to establishing early intervention as a means of creating new styles of family-based and community-based service in these countries in contrast to the hospital or institutional-services that were a legacy from a previous generation. Although formal evaluations are largely lacking, informal reports have been broadly enthusiastic. In sum, early intervention is no longer a new approach to developmental disabilities. It is an approach of proven effectiveness with children who have different impairments

  17. Early detection of first-episode psychosis

    DEFF Research Database (Denmark)

    Larsen, Tor K; Melle, Ingrid; Auestad, Bjørn

    2006-01-01

    Early intervention is assumed to improve outcome in first-episode psychosis, but this has not been proven.......Early intervention is assumed to improve outcome in first-episode psychosis, but this has not been proven....

  18. Early Identification of Psychosis: A Primer

    OpenAIRE

    Early Psychosis Initiative of British Columbia

    2000-01-01

    This document is an educational resource concerning the early identification of psychosis. Primary topics addressed include: an outline of the importance of early intervention; signs and symptoms of psychosis; and strategies for recognizing psychosis.  

  19. Two possibilities for New Siberian Islands terrane tectonic history during the Early Paleozoic based on paleomagnetic data

    Science.gov (United States)

    Metelkin, Dmitry V.; Chernova, Anna I.; Vernikovsky, Valery A.; Matushkin, Nikolay Yu.

    2017-04-01

    The New Siberian Islands (NSI), located in the East Siberian Sea in the junction region of various structural elements, are a key target for deciphering the tectonic evolution of the Eastern Arctic. In recent years, we went on several expeditions and gathered an extensive geological material for this territory. Among other things, we could prove that the basement of the De Long and Anjou archipelagos structures is Precambrian and the overlying Paleozoic sections formed within the same terrane. The form of the boundaries of the NSI terrane are actively debated and are probably continued from the Lyakhovsky islands in the south-west to the southern parts of the submerged Mendeleev Ridge, for which there is increasing evidence of continental crust. Today there are several models that interpret the Paleozoic-Mesozoic tectonic history and structural affiliation of the NSI terrane. Some propose that the Paleozoic sedimentary section formed in a passive margin setting of the Siberian paleocontinent. Others compare its history with marginal basins of the Baltica and Laurentia continents or consider the NSI terrane as an element of the Chukotka-Alaska microplate. These models are mainly based on results of paleobiogeographical and lithological-facies analyses, including explanations of probable sources for detrital zircons. Our paleomagnetic research on sedimentary, volcanogenic-sedimentary and igneous rocks of the Anjou (Kotelny and Bel'kovsky islands) and De Long (Bennett, Jeannette and Henrietta islands) archipelagos let us calculate an apparent polar wander path for the early Paleozoic interval of geological history, which allows us to conclude that the NSI terrane could not have been a part of the continental plates listed above, but rather had active tectonic boundaries with them. Our paleomagnetic data indicate that the NSI terrane drifted slowly and steadily in the tropical and subtropical regions no higher than 40 degrees. However, the main uncertainty for the

  20. Peering Into an Early Galaxy

    Science.gov (United States)

    Kohler, Susanna

    2018-04-01

    Thirteen billion years ago, early galaxies ionized the gas around them, producing some of the first light that brought our universe out of its dark ages. Now the Atacama Large Millimeter/submillimeter Array (ALMA) has provided one of the first detailed looks into the interior of one of these early, distant galaxies.Sources of LightArtists illustration of the reionization of the universe (time progresses left to right), in which ionized bubbles that form around the first sources of light eventually overlap to form the fully ionized universe we observe today. [Avi Loeb/Scientific American]For the first roughly hundred million years of its existence, our universe expanded in relative darkness there were no sources of light at that time besides the cosmic microwave background. But as mass started to condense to form the first objects, these objects eventually shone as the earliest luminous sources, contributing to the reionization of the universe.To learn about the early production of light in the universe, our best bet is to study in detail the earliest luminous sources stars, galaxies, or quasars that we can hunt down. One ideal target is the galaxy COSMOS Redshift 7, known as CR7 for short.Targeting CR7CR7 is one of the oldest, most distant galaxies known, lying at a redshift of z 6.6. Its discovery in 2015 and subsequent observations of bright, ultraviolet-emitting clumps within it have led to broad speculation about the source of its emission. Does this galaxy host an active nucleus? Or could it perhaps contain the long-theorized first generation of stars, metal-free Population III stars?To determine the nature of CR7 and the other early galaxies that contributed to reionization, we need to explore their gas and dust in detail a daunting task for such distant sources! Conveniently, this is a challenge that is now made possible by ALMAs incredible capabilities. In a new publication led by Jorryt Matthee (Leiden University, the Netherlands), a team of scientists now

  1. THE IMPORTANCE OF INVESTMENTS IN EARLY EDUCATION

    OpenAIRE

    DUMITRESCU Alexandra; CONSTANTINESCU Adrian; TACHE Ileana

    2012-01-01

    The early education is analyzed as being the most profitable investment in education (R. Cuhna). early education supports later learning opportunities. The economic dimension of early education takes into account the fact that the necessary investment for a child to benefit from early education services is rather low when looking at the cost (both economic and social) generated by a child who misses this education level, not necessarily because of the late education start but because of the l...

  2. Early diagnosis of the Spondyloarthropathies

    International Nuclear Information System (INIS)

    Gonzalez Naranjo, Luis Alonso; Londono, John D; Valle, Rafael Raul

    2005-01-01

    Spondyloarthropathies are a cluster of chronic inflammatory diseases that primarily include ankylosing spondylitis, reactive arthritis, psoriatic arthritis; arthritis associated with inflammatory bowel diseases and undifferentiated spondyloarthropathies. The most common subgroups of spondyloarthropathies are ankylosing spondylitis and undifferentiated spondyloarthropathy. The diagnosis of ankylosing spondylitis is mainly based on unequivocal radiographic sacroiliitis of at least grade 2 bilaterally or grade 3 unilaterally. How ever, in the early phase of disease, conventional radiographs are often too insensitive to show sacroiliitis and it usually takes several years for definite radiographic sacroiliitis to evolve. Thus, the diagnosis of ankylosing spondylitis is a commonly delayed by 8 to 11 years after the onset of symptoms. As a result, diagnosing axial spondyloarthropathy in the absence of radiographic sacroiliitis is very difficult to rheumatologists. In the early phase of disease, HLA B27 test and magnetic resonance imaging of sacroiliac joints may be helpful to the early diagnosis. In the presence of chronic low back pain the probability of axial spondyloarthropathy is about 5% and is about 14% if the back pain is inflammatory. The presence of = 3 features of spondyloarthropathy (heel pain, uveitis, dactylitis, positive family history, alternating buttock pain, psoriasis, inflammatory bowel disease, asymmetrical arthritis, positive response to anti-inflammatory drugs) increase the probability of axial spondyloarthropathy to 90%. Both, the positive HLA B27 and magnetic resonance imaging with signs of sacroiliitis increase the probability of spondyloarthropathy, particularly in patients without spondyloarthropathies features or with only 1 or 2 features. Since ankylosing spondylitis in association with psoriasis and inflammatory bowel disease is often HLA B27 negative, this test is of limited value under theses circumstances. Is important to consider that

  3. Observations of Early Optical Afterglows

    OpenAIRE

    Roming, Peter W. A.; Mason, Keith O.

    2006-01-01

    The Swift Ultra-Violet/Optical Telescope (UVOT) has performed extensive follow-up on 71 Swift Burst Alert Telescope triggered gamma-ray bursts (GRBs) in its first ten months of operations. In this paper, we discuss some of the UV and optical properties of UVOT detected afterglows such as XRF 050406, the bright GRB 050525A, the high redshift GRB 050730, the early flaring GRB 050801, and others. We also discuss some of the implications of why 75% of GRB afterglows observed by UVOT in less than ...

  4. Early discharge hospital at home.

    Science.gov (United States)

    Gonçalves-Bradley, Daniela C; Iliffe, Steve; Doll, Helen A; Broad, Joanna; Gladman, John; Langhorne, Peter; Richards, Suzanne H; Shepperd, Sasha

    2017-06-26

    Early discharge hospital at home is a service that provides active treatment by healthcare professionals in the patient's home for a condition that otherwise would require acute hospital inpatient care. This is an update of a Cochrane review. To determine the effectiveness and cost of managing patients with early discharge hospital at home compared with inpatient hospital care. We searched the following databases to 9 January 2017: the Cochrane Effective Practice and Organisation of Care Group (EPOC) register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, and EconLit. We searched clinical trials registries. Randomised trials comparing early discharge hospital at home with acute hospital inpatient care for adults. We excluded obstetric, paediatric and mental health hospital at home schemes.   DATA COLLECTION AND ANALYSIS: We followed the standard methodological procedures expected by Cochrane and EPOC. We used the GRADE approach to assess the certainty of the body of evidence for the most important outcomes. We included 32 trials (N = 4746), six of them new for this update, mainly conducted in high-income countries. We judged most of the studies to have a low or unclear risk of bias. The intervention was delivered by hospital outreach services (17 trials), community-based services (11 trials), and was co-ordinated by a hospital-based stroke team or physician in conjunction with community-based services in four trials.Studies recruiting people recovering from strokeEarly discharge hospital at home probably makes little or no difference to mortality at three to six months (risk ratio (RR) 0.92, 95% confidence interval (CI) 0.57 to 1.48, N = 1114, 11 trials, moderate-certainty evidence) and may make little or no difference to the risk of hospital readmission (RR 1.09, 95% CI 0.71 to 1.66, N = 345, 5 trials, low-certainty evidence). Hospital at home may lower the risk of living in institutional setting at six months (RR 0.63, 96% CI

  5. Early detection of congenital syphilis

    Directory of Open Access Journals (Sweden)

    Nagalakshmi Chowdhary

    2014-01-01

    Full Text Available Late congenital syphilis is a very rare clinical entity, and its early diagnosis and treatment is essential. Dental findings often provide valuable evidence for the diagnosis of late congenital syphilis. It occurs due to the transmission of the disease from an infected mother to her fetus through placenta. This long forgotten disease continues to effect pregnant women resulting in perinatal morbidity and mortality. Congenital syphilis is a preventable disease, and its presence reflects a failure of prenatal care delivery system, as well as syphilis control programs. We are reporting a case of late congenital syphilis with only Hutchinson′s teeth.

  6. Early history of military radiology

    International Nuclear Information System (INIS)

    Eisenberg, R.L.

    1991-01-01

    This paper reports that soon after Roentgen's discovery, physicians in the armed services of the major powers grasped the importance of x-ray sin military surgery. By May of 1896, radiographic examinations were being performed on Italian soldiers returning from the ill-fated Ethiopian campaign. Initially, radiographs were used for foreign body localization and the detection of fractures; later, a full range of diagnostic services was offered. The early challenges of obtaining x-ray examinations in the field - fragility of tubes and plates, mobility of machines and patients, and unpredictability of radiation dosage - became the basis for innovations that would fundamentally alter the daily practice of radiology in civilian life

  7. Examining Text Complexity in the Early Grades

    Science.gov (United States)

    Fitzgerald, Jill; Elmore, Jeff; Hiebert, Elfrieda H.; Koons, Heather H.; Bowen, Kimberly; Sanford-Moore, Eleanor E.; Stenner, A. Jackson

    2016-01-01

    The Common Core raises the stature of texts to new heights, creating a hubbub. The fuss is especially messy at the early grades, where children are expected to read more complex texts than in the past. But early-grades teachers have been given little actionable guidance about text complexity. The authors recently examined early-grades texts to…

  8. Ethics dilemmas of early detection of obesity

    DEFF Research Database (Denmark)

    Vallgårda, Signild

    2016-01-01

    Aim: To discuss the ethics dilemmas of the early detection of overweight and obesity. Methods: Analysis of the ethical aspects of early detection. Results: The early detection of overweight and obesity entails a number of ethical dilemmas because it may both be helpful and harmful. It may help...

  9. Early identification and intervention in cerebral palsy

    DEFF Research Database (Denmark)

    Herskind, Anna; Greisen, Gorm; Nielsen, Jens Bo

    2015-01-01

    Infants with possible cerebral palsy (CP) are commonly assumed to benefit from early diagnosis and early intervention, but substantial evidence for this is lacking. There is no consensus in the literature on a definition of 'early', but this review focuses on interventions initiated within...

  10. Early Childhood Inclusion in the United Kingdom

    Science.gov (United States)

    Blackburn, Carolyn

    2016-01-01

    A policy-to-practice paper is presented of early childhood inclusion in England. The article aims to report the benefits of early intervention services and early childhood inclusion for children with special educational needs and disabilities (SEND), document the chronology of policy development, and discuss research evidence about…

  11. Early Learning and Educational Technology Policy Brief

    Science.gov (United States)

    Lee, Joan

    2016-01-01

    Recognizing the growth of technology use in early learning settings, the U.S. Department of Education and U.S. Department of Health and Human Services collaborated in the development of the "Early Learning and Educational Technology Policy Brief" to promote developmentally appropriate use of technology in homes and early learning…

  12. Early infection and prognosis after acute stroke

    DEFF Research Database (Denmark)

    Kammersgaard, L P; Jørgensen, H S; Reith, J

    2001-01-01

    Infection is a frequent complication in the early course of acute stroke and may adversely affect stroke outcome. In the present study, we investigate early infection developing in patients within 3 days of admission to the hospital and its independent relation to recovery and stroke outcome....... In addition, we identify predictors for early infections, infection subtypes, and their relation to initial stroke severity....

  13. Early Smoking, Education, and Labor Market Performance

    NARCIS (Netherlands)

    Palali, Ali

    2015-01-01

    This study investigates the effects of early smoking on educational attainment and labor market performance. The results show that early smoking adversely affects educational attainment and initial labor market performance, but only for males. The effect of early smoking on initial labor market

  14. Early Archaean collapse basins, a habitat for early bacterial life.

    Science.gov (United States)

    Nijman, W.

    For a better definition of the sedimentary environment in which early life may have flourished during the early Archaean, understanding of the basin geometry in terms of shape, depth, and fill is a prerequisite. The basin fill is the easiest to approach, namely from the well exposed, low-grade metamorphic 3.4 - 3.5 Ga rock successions in the greenstone belts of the east Pilbara (Coppin Gap Greenstone Belt and North Pole Dome) in West Australia and of the Barberton Greenstone Belt (Buck Ridge volcano-sedimentary complex) in South Africa. They consist of mafic to ultramafic volcanic rocks, largely pillow basalts, with distinct intercalations of intermediate to felsic intrusive and volcanic rocks and of silicious sediments. The, partly volcaniclastic, silicious sediments of the Buck Ridge and North Pole volcano-sedimentary complexes form a regressive-transgressive sequence. They were deposited close to base level, and experienced occasional emersion. Both North Pole Chert and the chert of the Kittys Gap volcano-sedimentary complex in the Coppin Gap Greenstone Belt preserve the flat-and-channel architecture of a shallow tidal environment. Thickness and facies distribution appear to be genetically linked to systems, i.e. arrays, of syn-depositionally active, extensional faults. Structures at the rear, front and bottoms of these fault arrays, and the fault vergence from the basin margin towards the centre characterize the basins as due to surficial crustal collapse. Observations in the Pilbara craton point to a non-linear plan view and persistence for the basin-defining fault patterns over up to 50 Ma, during which several of these fault arrays became superposed. The faults linked high-crustal level felsic intrusions within the overall mafic rock suite via porphyry pipes, black chert veins and inferred hydrothermal circulations with the overlying felsic lavas, and more importantly, with the cherty sediments. Where such veins surfaced, high-energy breccias, and in the

  15. Early occurring and continuing effects

    International Nuclear Information System (INIS)

    Scott, B.R.; Hahn, F.F.

    1985-01-01

    This chapter deals with health-risk estimates for early and continuing effects of exposure to ionizing radiations that could be associated with light water nuclear power plants accidents. Early and continuing effects considered are nonneoplastic diseases and symptoms that normally occur soon after radiation exposure, but may also occur after years have passed. They are generally associated with relatively high (greater than 1 Gy) doses. For most of the effects considered, there is a practical dose threshold. Organs of primary interest, because of their high sensitivity or the likelihood of receiving a large radiation dose, are bone marrow, gastrointestinal tract, thyroid glands, lungs, skin, gonads, and eyes. In utero exposure of the fetus is also considered. New data and modeling techniques available since publication of the Reactor Safety Study (WASH 1400, 1975) were used along with data cited in the Study to develop improved health-risk models for morbidity and mortality. The new models are applicable to a broader range of accident scenarios, provide a more detailed treatment of dose protraction effects, and include morbidity effects not considered in the Reactor Safety Study. 115 references, 20 figures, 19 tables

  16. Cerebrovascular Diseases and Early Seizure

    Directory of Open Access Journals (Sweden)

    Ayşegül Gündüz

    2006-08-01

    Full Text Available OBJECTIVE: Cerebrovascular disease is one of the important causes of seizures and epilepsy among the advanced age group. Seziures are found to be associated with lesion localization and size in previous studies. METHODS: Here, we aimed to detect prevelance of seizure, relation of seizure and lesion localization, and observed seizure types. RESULTS: Three hundred seventy eight patients with ischemic cerebrovascular disease or intraparenchymal hemorrhage who were followed in Cerrahpasa IVIedical School clinic were studied retrospectively and probability of seizure occurence within 1 month after stroke was evaluated. CONCLUSION: Among 378 patients hospitalized by acute stroke, 339 were diagnosed as ischemic cerebrovascular disease and 39 (10.3% had primary intraparenchymal hematoma. Seizures were observed in 16 patients (4.2%, 2 (%5.1 in intraparenchymal hematoma group and 14 (%4.1 in ischemic cerebrovascular disease. Early seizures were detected in 33% of patients with anterior cerebral artery, in 6.8% of posterior cerebral artery and in 3.3% of middle cerebral artery infarcts and in three patients out of 12 who were known to have epilepsy. Seizure types were secondarily generalised tonic-clonic seizure in nine cases (57%. Among whole group status epilepticus was observed in four patients (1.1%. Conclusion: Early seizure rates are found to be high among patients with anterior cerebral artery infarct and known epilepsy

  17. EGU's Early Career Scientists Network

    Science.gov (United States)

    Roberts Artal, L.; Rietbroek, R.

    2017-12-01

    The EGU encourages early career scientists (ECS) to become involved in interdisciplinary research in the Earth, planetary and space sciences, through sessions, social events and short courses at the annual General Assembly in April and throughout the year. Through division-level representatives, all ECS members can have direct input into matters of the division. A Union-wide representative, who sits on the EGU Council, ensures that ECS are heard at a higher level in the Union too. After a brief introduction as to how the network is organised and structured, this presentation will discuss how EGU ECS activities have been tailored to the needs of ECS members and how those needs have been identified. Reaching and communicating opportunities to ECS remains an ongoing challenge; they will be discussed in this presentation too, as well as some thoughts on how to make them more effective. Finally, the service offered to EGU ECS members would certainly benefit from building links and collaboration with other early career networks in the geosciences. This presentation will outline some of our efforts in that direction and the challenges that remain.

  18. Evidence for an Early-Middle Miocene age of the Navidad Formation (central Chile: Paleontological, paleoclimatic and tectonic implications Evidencias de una edad miocena temprana-media de la Formación Navidad: Implicancias paleontológicas, paleoclimáticas y tectónicas

    Directory of Open Access Journals (Sweden)

    Néstor M Gutiérrez

    2013-01-01

    Full Text Available The age of the Navidad Formation in central Chile has always been controversial, mainly due to the conflicting age ranges indicated by its macro- and microfossils. Macrofossils are generally interpreted as having been reworked from older, Early to Middle Miocene strata, whereas a Late Miocene-Pliocene age has been accepted on the basis of planktonic foraminifer index species. The results of this study, however, indicate that the macrofossils occur in situ, which necessitates a complete revision of the geochronological data. It is concluded that the evidence for an Early to Middle Miocene age is overwhelming, and that the planktonic foraminifer index species must have appeared in the SE Pacific earlier than elsewhere. These include Globoturborotalia apertura, Globorotalia puncticulata (Deshayes, Globorotalia spheriomizea (Walters, Neogloboquadrina pachyderma (Ehrenberg, and Neogloboquadrina acostaensis (Blow. An Early to Middle Miocene age for the Navidad Formation correlates well with a reinterpretation of its depo-sitional environment as a continental shelf instead of a deepwater continental slope, global and regional paleoclimatic events, and the tectonic development of the Andes Range.La edad de la Formación Navidad en Chile central siempre ha sido controversial, debido a los distintos rangos de edad indicados por los macro- y microfósiles. En general, se considera que los macro-fósiles han sido retrabajados de estratos del Mioceno Temprano a Medio, y se aceptó una edad miocena tardía para esta unidad sobre la base de especies indicadoras de foraminíferos planctónicos. Sin embargo, los resultados de este estudio indican que los macrofósiles ocurren in situ, lo cual hace necesario una revisión completa de los datos geocronológicos. Se concluye que la evidencia por una edad miocena temprana a media es contundente, y que los foraminíferos planctónicos que indicarían una edad miocena tardía aparecieron más temprano en el SE del oc

  19. Overview of Play: Its Uses and Importance in Early Intervention/Early Childhood Special Education

    Science.gov (United States)

    Lifter, Karin; Foster-Sanda, Suzanne; Arzamarski, Caley; Briesch, Jacquelyn; McClure, Ellen

    2011-01-01

    Play is a natural activity of early childhood, which has great relevance to the fields of early intervention, early childhood special education, and early childhood education. Within these fields, ongoing tensions persist in how play is described and used. These tensions compromise activities of assessment, intervention, and curriculum development…

  20. Recent Coverage of Early Childhood Education Approaches in Open Access Early Childhood Journals

    Science.gov (United States)

    Keskin, Burhanettin

    2016-01-01

    A content analysis of the coverage of the major approaches to early childhood education in the early childhood research journals, published between 2010 and 2014, that are early childhood research oriented and have free online access were investigated. Among 21 journals in early childhood education, two journals were selected for the content…

  1. Ultrasonographic findings of early abortion: suggested predictors

    International Nuclear Information System (INIS)

    Jun, Soon Ae; Ahn, Myoung Ock; Cha, Kwang Yul; Lee, Young Doo

    1992-01-01

    To investigate predictable ultrasonographic findings of early abortion. To investigate objective rules for the screening of abortion. Ultrasonographic examination of 111 early pregnancies between the sixth and ninth week in women who had regular 28 day menstrual cycles was performed. Ultrasonographic measurements of the gestational sac, crown rump length and fetal heart rate were performed using a linear array real time transducer with doppler ultrasonogram. All measurements of 17 early abortions were compared to those of 94 normal pregnancies. Most of early aborted pregnancies were classified correctly by discriminant analysis with G-SAC and CRL (G-SAC=0.5 CRL + 15, sensitivity 76.5%, specificity 96.8%). With the addition of FHR, 94.1% of early abortions could be predicted. In conclusion, ultrasonographic findings of early intrauterine growth retardation, small gestational sac and bradycardia can be predictable signs suggestive of poor prognosis of early pregnancies

  2. determination of origin and channel sediments of o on of origin and ...

    African Journals Online (AJOL)

    user pc

    2017-12-02

    Dec 2, 2017 ... south-western Nigeria, is part of Nigerian complex which belongs to the. Precambrian to Early Paleozoic orogeny, comprises. Precambrian crystalline rocks with associated infold. Schist belts. The South-western Nigeria that hosts the study area (Osi) is gener represented by series of older metasediments a.

  3. Palaeoecology and depositional environments of the Tendaguru Beds (Late Jurassic to Early Cretaceous, Tanzania

    Directory of Open Access Journals (Sweden)

    M. Aberhan

    2002-01-01

    Full Text Available The Late Jurassic to Early Cretaceous Tendaguru Beds (Tanzania, East Africa have been well known for nearly a century for their diverse dinosaur assemblages. Here, we present sedimentological and palaeontological data collected by the German-Tanzanian Tendaguru Expedition 2000 in an attempt to reconstruct the palaeo-ecosystems of the Tendaguru Beds at their type locality. Our reconstructions are based on sedimentological data and on a palaeoecological analysis of macroinvertebrates, microvertebrates, plant fossils and microfossils (ostracods, foraminifera, charophytes, palynomorphs. In addition, we included data from previous expeditions, particularly those on the dinosaur assemblages. The environmental model of the Tendaguru Beds presented herein comprises three broad palaeoenvironmental units in a marginal marine setting: (1 Lagoon-like, shallow marine environments above fair weather wave base and with evidence of tides and storms. These formed behind barriers such as ooid bar and siliciclastic sand bar complexes and were generally subject to minor salinity fluctuations. (2 Extended tidal flats and low-relief coastal plains. These include low-energy, brackish coastal lakes and ponds as well as pools and small fluvial channels of coastal plains in which the large dinosaurs were buried. Since these environments apparently were, at best, poorly vegetated, the main feeding grounds of giant sauropods must have been elsewhere. Presumably, tidal flats and coastal plains were visited by dinosaurs primarily during periods of drought. (3 Vegetated hinterland. Vegetation of this environment can only be inferred indirectly from plant material transported into the other depositional environments. Vegetation was dominated by a diverse conifer flora, which apparently formed part of the food source of large herbivorous sauropods. Evidence from various sources suggests a subtropical to tropical palaeoclimate, characterised by seasonal rainfall alternating with

  4. Early School Leaving in Scandinavia

    DEFF Research Database (Denmark)

    Jakobsen, Vibeke; Bäckman, Olof; Lorentzen, Thomas

    2015-01-01

    countries and find the highest vocational track dropout rates in Norway and the lowest in Finland. The results indicate that the relative labour market effect of dropping out from a vocational track is most detrimental in Norway. It is also in Norway that we find the greatest gender differences......The article explores the extent to which the organization of vocational tracks in upper secondary school affects the labour market risks associated with early school exit. The Nordic countries share many features, but the upper secondary school systems differ significantly in how their vocational...... tracks are organized. Denmark and Norway have dual vocational tracks, that is, they combine school-based education and workplace apprenticeships, whereas in Finland and Sweden they are primarily school based. We analyse administrative longitudinal data from the mid-1990s to the mid-2000s in the four...

  5. Excess Early Mortality in Schizophrenia

    DEFF Research Database (Denmark)

    Laursen, Thomas Munk; Nordentoft, Merete; Mortensen, Preben Bo

    2014-01-01

    Schizophrenia is often referred to as one of the most severe mental disorders, primarily because of the very high mortality rates of those with the disorder. This article reviews the literature on excess early mortality in persons with schizophrenia and suggests reasons for the high mortality...... as well as possible ways to reduce it. Persons with schizophrenia have an exceptionally short life expectancy. High mortality is found in all age groups, resulting in a life expectancy of approximately 20 years below that of the general population. Evidence suggests that persons with schizophrenia may...... not have seen the same improvement in life expectancy as the general population during the past decades. Thus, the mortality gap not only persists but may actually have increased. The most urgent research agenda concerns primary candidates for modifiable risk factors contributing to this excess mortality...

  6. LEP vacuum chamber, early prototype

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The structure of LEP, with long bending magnets and little access to the vacuum chamber between them, required distributed pumping. This is an early prototype for the LEP vacuum chamber, made from extruded aluminium. The main opening is for the beam. The small channel to the right is for cooling water, to carry away the heat deposited by the synchroton radiation from the beam. The 4 slots in the channel to the left house the strip-shaped ion-getter pumps (see 7810255). The ion-getter pumps depended on the magnetic field of the bending magnets, too low at injection energy for the pumps to function well. Also, a different design was required outside the bending magnets. This design was therefore abandoned, in favour of a thermal getter pump (see 8301153 and 8305170).

  7. How early and how long?

    Directory of Open Access Journals (Sweden)

    Mette Løvgren

    2012-01-01

    Full Text Available Abstract: Day care centres have become a normal part of Norwegian childhood, even among quite small children. In 1970 less than 3 per cent of Norwegian children of pre-school were enrolled. At the end of 2009 as much as 70 per cent of children aged 12 to 24 months were enrolled and for 90 per cent of them a full day stay had been arranged. Norwegian children with small children opt for an early start at a day care centre. However, the day care centre employees do not share the same views as the users of the services they provide. Only one third of them express the opinion that children may start at the age of one and have a full day stay at this age. The article discusses this discrepancy between the users and providers of public financed day care.

  8. LHCb Early Career Scientist Awards

    CERN Multimedia

    Patrick Koppenburg for the LHCb Collaboration

    2016-01-01

    On 15 September 2016, the LHCb collaboration awarded the first set of prizes for outstanding contributions of early career scientists.   From left to right: Guy Wilkinson (LHCb spokesperson), Sascha Stahl, Kevin Dungs, Tim Head, Roel Aaij, Conor Fitzpatrick, Claire Prouvé, Patrick Koppenburg (chair of committee) and Sean Benson. Twenty-five nominations were submitted and considered by the committee, and 5 prizes were awarded to teams or individuals for works that had a significant impact within the last year. The awardees are: Roel Aaij, Sean Benson, Conor Fitzpatrick, Rosen Matev and Sascha Stahl for having implemented and commissioned the revolutionary changes to the LHC Run-2 high-level-trigger, including the first widespread deployment of real-time analysis techniques in High Energy Physics;   Kevin Dungs and Tim Head for having launched the Starterkit initiative, a new style of software tutorials based on modern programming methods. “Starterkit is a group of ph...

  9. Chandra Early Type Galaxy Atals

    Science.gov (United States)

    Kim, Dong-Woo; Anderson, Craig; Burke, Douglas J.; Fabbiano, Giuseppina; Fruscione, Antonella; Lauer, Jennifer; McCollough, Michael; Morgan, Douglas; Mossman, Amy; O'Sullivan, Ewan; Paggi, Alessandro; Vrtilek, Saeqa Dil; Trinchieri, Ginevra

    2017-08-01

    The hot gas in early type galaxies (ETGs) plays a crucial role in understanding their formation and evolution. As the hot gas is often extended to the outskirts beyond the optical size, the large scale structural features identified by Chandra (including jets, cavities, cold fronts, filaments and tails) point to key evolutionary mechanisms, e.g., AGN feedback, merging history, accretion, stripping and star formation and its quenching. We have systematically analyzed the archival Chandra data of ~100 ETGs to study the hot ISM. We produce the uniformly derived data products with spatially resolved spectral information and will make them accessible via a public web site. With 2D spectral infomation, we further discuss gas morphology, scaling relations, X-ray based mass profiles and their implications related to various physical mechanisms (e.g., stellar and AGN feedback).

  10. Atypical manifestations of early syphilis

    Directory of Open Access Journals (Sweden)

    R V Koranne

    1990-01-01

    Full Text Available A study of 36 untreated patients with early syphilis revealed atypical variations namely; long incubation period of 101 days in I patient, more than 3 chancres in 1, undermined margin of the chancre along with tenderness in 1 and moderate to severe tenderness of the ulcers in 2 cases. In 3 patients there was no indurations of the ulcers. Three patients with primary syphilis had unilateral lymphadenitis, and in I case the lymph nodes were not only tender but showed tendency towardsmatingawell. Insecondarysyphilis, 11 out of 16 patients having condylomata lata had no other muco-cutaneous lesions. Concomitant presence of other venereal disease to account for the atypical manifestations was discounted- by appropriate laboratory tests, response to therapeutic agents and follow up.

  11. Women, motherhood and early childhood

    DEFF Research Database (Denmark)

    Ravnbøl, Camilla Ida

    This paper explores the question of how Roma women’s situation influences Roma children’s survival, growth and development in the early years. It focuses specifically on the barriers and opportunities for action that Roma women experience and how these influence their possibilities to engage...... in efforts for their young children. The paper adopts the perspective that in poor and socially excluded Roma communities, young children’s survival, growth and development cannot be addressed effectively if the rights of women are overlooked. Roma women navigate in contexts where they, as women, experience...... an assessment of the mothers’ capacity to internalize and act upon advice. It is argued that supporting Roma women’s access to human rights is likely to have positive outcomes for the women and their families, especially the young children...

  12. Physics of the early universe

    International Nuclear Information System (INIS)

    Brandenberger, R.H.

    1987-01-01

    When studying the evolution of the very early universe it is necessary to use a description of matter which is appropriate at very high energies, namely in terms of quantum fields. In such models there may be a period during which the ratio of pressure and energy density is - 1, an equation of state which leads to an exponential expansion of the universe (inflation). There may also arise stable topological defects similar to vortex lines in condensed matter physics. These defects (cosmic strings) form seeds about which gas can accrete to form galaxies and clusters of galaxies. The author reviews inflation and cosmic strings, emphasizing their role in generating the energy density perturbations which are required in order to explain the existence of structures in the universe

  13. Acute leukemia in early childhood

    Directory of Open Access Journals (Sweden)

    M. Emerenciano

    2007-06-01

    Full Text Available Acute leukemia in early childhood is biologically and clinically distinct. The particular characteristics of this malignancy diagnosed during the first months of life have provided remarkable insights into the etiology of the disease. The pro-B, CD10 negative immunophenotype is typically found in infant acute leukemia, and the most common genetic alterations are the rearrangements of the MLL gene. In addition, the TEL/AML1 fusion gene is most frequently found in children older than 24 months. A molecular study on a Brazilian cohort (age range 0-23 months has detected TEL/AML1+ve (N = 9, E2A/PBX1+ve (N = 4, PML/RARA+ve (N = 4, and AML1/ETO+ve (N = 2 cases. Undoubtedly, the great majority of genetic events occurring in these patients arise prenatally. The environmental exposure to damaging agents that give rise to genetic changes prenatally may be accurately determined in infants since the window of exposure is limited and known. Several studies have shown maternal exposures that may give rise to leukemogenic changes. The Brazilian Collaborative Study Group of Infant Acute Leukemia has found that mothers exposed to dipyrone, pesticides and hormones had an increased chance to give birth to babies with infant acute leukemia [OR = 1.48 (95%CI = 1.05-2.07, OR = 2.27 (95%CI = 1.56-3.31 and OR = 9.08 (95%CI = 2.95-27.96], respectively. This review aims to summarize recent clues that have facilitated the elucidation of the biology of early childhood leukemias, with emphasis on infant acute leukemia in the Brazilian population.

  14. The early Earth atmosphere and early life catalysts.

    Science.gov (United States)

    Ramírez Jiménez, Sandra Ignacia

    2014-01-01

    Homochirality is a property of living systems on Earth. The time, the place, and the way in which it appeared are uncertain. In a prebiotic scenario two situations are of interest: either an initial small bias for handedness of some biomolecules arouse and progressed with life, or an initial slight excess led to the actual complete dominance of the known chiral molecules. A definitive answer can probably never be given, neither from the fields of physics and chemistry nor biology. Some arguments can be advanced to understand if homochirality is necessary for the initiation of a prebiotic homochiral polymer chemistry, if this homochirality is suggesting a unique origin of life, or if a chiral template such as a mineral surface is always required to result in an enantiomeric excess. A general description of the early Earth scenario will be presented in this chapter, followed by a general description of some clays, and their role as substrates to allow the concentration and amplification of some of the building blocks of life.

  15. Biosignatures observed by Raman mapping in silicified materials

    Science.gov (United States)

    Foucher, F.; Westall, F.; Knoll, A.

    2012-04-01

    Establishing the biogenicity of ancient microbial remains is relatively difficult due to their simple shape and small size (micrometric-submicrometric). Potential biosignatures that remain in the rocks are related to morphological aspects of the potential microfossils, their chemical composition (carbon and associated elements), and evidence for metabolic activity (elemental isotopic signature, biominerals, corrosion/leaching features). Detection of biosignatures related to each of these microbial characteristics will increase the confidence with which biogenicity can be assigned to an unknown structure. However, given the small size of the microfossils and the consequent faint organic/geochemical traces, sophisticated instrumentation, such as mass spectrometers, electron microscopes, proton probes, nano-SIMS or even synchrotrons is generally required. In this study, we demonstrate the usefulness of Raman spectroscopy, and in particular Raman mapping, as a very powerful tool for the study of both organic and minerals biosignatures. Our investigations concern silicified, carbonaceous-walled microfossils from the Precambrian (700-800 Ma) Draken Formation, Spitsbergen (Svalbard). The microfossils consist of filamentous cyanobacterial mats containing trapped coccoidal planktonic microorganisms. The filaments are generally ~5 µm in width and the coccoidal structures are ~10µm in diameter. The Raman spectrometer used (WITec Alpha500 RA) allows compositional 2D/3D mapping at a sub-micrometric resolution of fossilised microorganisms, whose biogenicity had been previously established on the basis of their morphological characteristics and carbonaceous composition [1]. Complementary features were revealed by the micro-Raman mapping that may aid interpretation of biogenicity in an unknown structure. They included detection of opaline silica, titanium dioxide (anatase), pyrite and hydroxyapatite associated with the microfossils. Opaline silica is metastable and normally

  16. EARLY POSTOPERATIVE COMPLICATIONS AFTER RADICAL CYSTECTOMY

    Directory of Open Access Journals (Sweden)

    V. O. Mager

    2014-08-01

    Full Text Available Radical cystectomy (RCE is associated with a considerable number of early postoperative complications as before. Based on 10 years’ experience, this paper demonstrates the frequency (33.9 % and types of early complications following RCE, as well as postoperative mortality (5.5 % and its resulting causes. Although postoperative mortality is relatively low today, the frequency of early postoperative complications remains high as before.

  17. Early rehabilitation and participation in focus

    DEFF Research Database (Denmark)

    Pallesen, Hanne; Buhl, Inge; Roenn-Smidt, Helle

    2016-01-01

    Early neurorehabilitation is an interdisciplinary field. Thus, in order to eliminate unnecessary barriers for individuals with severe acquired brain injury in early rehabilitation, we need rehabilitation science that supports both quantitative and qualitative research methods. Participation can...... be studied directly and indirectly. This commentary proposes that active participation and the ‘‘lived body’’ are essential terms in early rehabilitation of severe ABI patients, and a description of how these terms are interpreted and handled in the practice is needed....

  18. The Pindiro Group (Triassic to Early Jurassic Mandawa Basin, southern coastal Tanzania): Definition, palaeoenvironment, and stratigraphy

    Science.gov (United States)

    Hudson, W. E.; Nicholas, C. J.

    2014-04-01

    This paper defines the Pindiro Group of the Mandawa Basin, southern coastal Tanzania based on studies conducted between 2006 and 2009 with the objective of understanding the evolution of this basin. This work draws upon field data, hydrocarbon exploration data, unconventional literature, and the scant published materials available. The paper focuses on the evolution, depositional environments, and definition of the lowermost sedimentary package, which overlies unconformably the metamorphic basement of Precambrian age. The package is described here as the Pindiro Group and it forms the basal group of the Mandawa Basin stratigraphy.

  19. Genetics of Severe Early Onset Epilepsies

    Science.gov (United States)

    2017-08-24

    Epilepsy; Epileptic Encephalopathy; Ohtahara Syndrome; Infantile Spasms; Dravet Syndrome; Malignant Migrating Partial Epilepsy of Infancy; Early Myoclonic Epileptic Encephalopathy; PCDH19-related Epilepsy and Related Conditions

  20. Positioning and early mobilisation in stroke.

    Science.gov (United States)

    Keating, Moira; Penney, Maree; Russell, Petra; Bailey, Emma

    Stroke unit care, providing early rehabilitation, improves long-term outcomes for patients following a stroke. Early mobilisation and good positioning are recognised as key aspects of care in stroke units. Nurses working on stroke units have an important role because they are able to implement positioning and early mobilisation strategies 24 hours a day, reducing the risk of complications and improving functional recovery. Patients benefit if nurses work effectively with the therapy team in positioning and early mobilisation. Nurses also need appropriate training and expertise to make best use of specialist equipment.

  1. Scientific spirit in early childhood

    Directory of Open Access Journals (Sweden)

    Isabel Samacá Bohórquez

    2016-01-01

    Full Text Available Play and fun are key elements in the pedagogical work with five-year school children, since the teacher is required to carry out a hermeneutical and phenomenological exercise coming from the interaction among the different languages used by children to communicate their thoughts, emotions and ideas. In order to reflect about the scientific spirit in early childhood, it is necessary firstly to think about how its logic develops and operates and about the need to recognize in the sociocultural environment the possibilities to stimulate talents or the limitations demarcating their development, secondly, teaching practice must be thought in order to establish dialogue forums with students to know their needs and interests and guide their searches. To meet other is possible for children to the extent that the dialogical principle of knowledge interaction is recognized and the discovery of tensions and meeting points around the educational praxis, as an approach to infant’s rationality and his/her ways of learning, towards the social construction of boy and girl gender identity in our society.

  2. Early vision and focal attention

    Science.gov (United States)

    Julesz, Bela

    1991-07-01

    At the thirty-year anniversary of the introduction of the technique of computer-generated random-dot stereograms and random-dot cinematograms into psychology, the impact of the technique on brain research and on the study of artificial intelligence is reviewed. The main finding-that stereoscopic depth perception (stereopsis), motion perception, and preattentive texture discrimination are basically bottom-up processes, which occur without the help of the top-down processes of cognition and semantic memory-greatly simplifies the study of these processes of early vision and permits the linking of human perception with monkey neurophysiology. Particularly interesting are the unexpected findings that stereopsis (assumed to be local) is a global process, while texture discrimination (assumed to be a global process, governed by statistics) is local, based on some conspicuous local features (textons). It is shown that the top-down process of "shape (depth) from shading" does not affect stereopsis, and some of the models of machine vision are evaluated. The asymmetry effect of human texture discrimination is discussed, together with recent nonlinear spatial filter models and a novel extension of the texton theory that can cope with the asymmetry problem. This didactic review attempts to introduce the physicist to the field of psychobiology and its problems-including metascientific problems of brain research, problems of scientific creativity, the state of artificial intelligence research (including connectionist neural networks) aimed at modeling brain activity, and the fundamental role of focal attention in mental events.

  3. Early detection of materials degradation

    Science.gov (United States)

    Meyendorf, Norbert

    2017-02-01

    Lightweight components for transportation and aerospace applications are designed for an estimated lifecycle, taking expected mechanical and environmental loads into account. The main reason for catastrophic failure of components within the expected lifecycle are material inhomogeneities, like pores and inclusions as origin for fatigue cracks, that have not been detected by NDE. However, material degradation by designed or unexpected loading conditions or environmental impacts can accelerate the crack initiation or growth. Conventional NDE methods are usually able to detect cracks that are formed at the end of the degradation process, but methods for early detection of fatigue, creep, and corrosion are still a matter of research. For conventional materials ultrasonic, electromagnetic, or thermographic methods have been demonstrated as promising. Other approaches are focused to surface damage by using optical methods or characterization of the residual surface stresses that can significantly affect the creation of fatigue cracks. For conventional metallic materials, material models for nucleation and propagation of damage have been successfully applied for several years. Material microstructure/property relations are well established and the effect of loading conditions on the component life can be simulated. For advanced materials, for example carbon matrix composites or ceramic matrix composites, the processes of nucleation and propagation of damage is still not fully understood. For these materials NDE methods can not only be used for the periodic inspections, but can significantly contribute to the material scientific knowledge to understand and model the behavior of composite materials.

  4. Casebooks in Early Modern England:

    Science.gov (United States)

    Kassell, Lauren

    2014-01-01

    summary Casebooks are the richest sources that we have for encounters between early modern medical practitioners and their patients. This article compares astrological and medical records across two centuries, focused on England, and charts developments in the ways in which practitioners kept records and reflected on their practices. Astrologers had a long history of working from particular moments, stellar configurations, and events to general rules. These practices required systematic notation. Physicians increasingly modeled themselves on Hippocrates, recording details of cases as the basis for reasoned expositions of the histories of disease. Medical records, as other scholars have demonstrated, shaped the production of medical knowledge. Instead, this article focuses on the nature of casebooks as artifacts of the medical encounter. It establishes that casebooks were serial records of practice, akin to diaries, testimonials, and registers; identifies extant English casebooks and the practices that led to their production and preservation; and concludes that the processes of writing, ordering, and preserving medical records are as important for understanding the medical encounter as the records themselves. PMID:25557513

  5. Cosmology and the early universe

    Science.gov (United States)

    Joshi, Abhigna

    2017-01-01

    In the beginning the universe was in a hot dense state nearly 13.8 billion years ago. The thermal history of the universe was traced back to an era when the temperature was about 1012K. At this early time, the universe was filled with particles-mostly photons and leptons- whose interactions are hopefully weak enough to allow this medium to be treated as a more or less ideal gas. However, if we look back a little further, into the first 0.0001 second of cosmic history when the temperature was above 1012K. At such temperatures, there will be present in thermal equilibrium copious numbers of strongly interacting particles-mostly masons and baryons-with a mean interparticle distance less than a Compton wavelength. These particles will be in a state of continual mutual interaction, and cannot reasonably be expected to obey any simple equation of state. The inflationary epoch lasted from 10-36seconds after the Big Bang to sometime between 10-33and 10-32seconds. Matter and energy created in this time. Right after that space expanded exponentially with enormous rate of 74.3 +/-2.1Km per second per Mpc. Undergraduate student and researcher of the string theory, quantum gravity, cosmology and quantum biology.

  6. Cerebellar ataxia of early onset

    International Nuclear Information System (INIS)

    Yamashita, Sumimasa; Miyake, Shota; Yamada, Michiko; Iwamoto, Hiroko; Yamada, Kazuhiko.

    1989-01-01

    Eight cases of childhood cerebellar ataxia were reported. All these cases showed chronic cerebellar ataxia with early onset, and the other diseases of cerebellum such as infections, neoplasms and storage diseases were excluded by clinical symptoms and laboratory findings including blood counts, blood chemistry, lactate, pyruvate, ceruloplasmine, urinalysis, serum immunoglobulins, amino acid analysis in blood and urine, CSF analysis, leukocyte lysosomal enzymes, MCV, EMG, EEG and brain X-CT. Two pairs of siblings were included in this study. The clinical diagnosis were cerebellar type (5), spinocerebellar type (1), one Marinesco-Sjoegren syndrome and undetermined type (1). The age of onset was 1 to 5 years. The chief complaint was motor developmental delay in 6 cases; among them 5 patients could walk alone at the ages of 2 to 3 years'. Mental retardation was observed in 7 cases and epilepsy in 2. TRH was effective in 5 cases. The MRI study revealed that the area of medial sagittal slice of the cerebellum was reduced significantly in all cases and also that of pons was reduced in 5 cases. Different from typical adult onset spinocerebellar degenerations, most of the present cases have achieved slow developmental milestones and the clinical course was not progressive. Genetic factors are suspected in the pathogenesis of this disease in some cases. (author)

  7. Early Byzantine steelyard from Belgrade

    Directory of Open Access Journals (Sweden)

    Vujović Miroslav

    2014-01-01

    Full Text Available The initial aim of this paper was to present scholarly circles with a detailed report about the insufficiently known Early Byzantine steelyard beam (Figs. 2-5; Pl. I/1 treasured in Belgrade City Museum (further in the text BCM together with a small counterweight (Fig. 6; Pl. I/2 which, judging by its dimensions and weight, does not belong to it. However, after inspecting the documentation of BCM and the National Museum in Belgrade (further in the text NMB, the supposition that the steelyard beam from BCM represents a part of the same hoard with the well known counterweight (Fig. 7 in the form of a bust of a Byzantine empress, and the unpublished chain system with hooks for hanging loads (Fig. 8; Pl. IV, which are kept in NMB, was confirmed. The detailed examination of the museum inventory records shed light on the set of circumstances which led to the separation of the parts of the Belgrade steelyard. [Projekat Ministarstva nauke Republike Srbije, br. 177007: Romanizacija, urbanizacija i transformacija urbanih centara civilnog,vojnog i rezidencijalnog karaktera u rimskim provincijama na tlu Srbije

  8. On a chaotic early universe

    International Nuclear Information System (INIS)

    Tomita, Kenji.

    1974-11-01

    The theories regarding the origin of galaxies and elements are reviewed in this paper, and the assumptions made for these theories are discussed. It has been assumed that the universe has always been isotropic and homogeneous from the beginning of cosmic expansion. At the stage of very high density that any local irregularities such as galaxies cannot exist, the admissible deviation in this case from the mean value is only the statistical or quantum fluctuation of matter density, spatial curvature or their growth. It should be considered that the chemical composition of matters at the earliest stage consisted of most fundamental particles. However, if the fluctuation of matter density is statistical, the present values are too small. As for the origin of elements, it depends strongly on the period when cosmic radiation appeared. The final mass ratios of elements are given from the present baryon mass density, and are in agreement with observed values. The assumption of hot universe seems good. However, the time-independent ratio of photon number to baryon number is hardly understood. It is reasonable to assume for the early universe an inhomogeneous model whose space-time curvature is of turbulent character, according to weak cosmological principle. The inhomogeneous models to be considered are weakly non-linear perturbation theory, anti-Newtonian approximation and post anti-Newtonian approximation. Smoothing-out process, the origin of cosmic microwave radiation, the origin of galaxies and the origin of chemical elements are discussed. (Kato, T.)

  9. Timing of Early Aptian demise of northern Tethyan carbonate platforms - chemostratigraphic versus biostratigraphic evidence

    Science.gov (United States)

    Huck, Stefan; Immenhauser, Adrian; Heimhofer, Ulrich; Rameil, Niels

    2010-05-01

    platform related to the unfolding oceanic anoxic event 1a (« Selli event »). Revue de Paléobiologie, 27, 461-468. Gradstein, F.M., Ogg, J.G., Smith, A.G., Bleeker, W. and Lourens, L.J. (2004) A new Geologic Time Scale, with special reference to Precambrian and Neogene. Episodes, 27, 83-100. Huck, S., Rameil, N., Korbar, T., Heimhofer, U., Wieczorek, T.D. and Immenhauser, A. (2010) Latitudinally different responses of Tethyan shoal-water carbonate systems to the Early Aptian oceanic anoxic event (OAE 1a). Sedimentology (pending acceptance of revised version). Moreno-Bedmar, J.A., Company, M., Bover-Arnal, T., Salas, R., Delanoy, G., Martinez, R. and Grauges, A. (2009) Biostratigraphic characterization by means of ammonoids of the lower Aptian Oceanic Anoxic Event (OAE 1a) in the eastern Iberian Chain (Maestrat Basin, eastern Spain). Cretaceous Research, 30, 864-872. Rameil, N., Immenhauser, A., Warrlich, G.M.D., Vahrenkamp, V.C., Hillgärtner, H., Droste, H.J., Al-Mahruqi, I., Buhl, D., Schulte, U. and Kunkel, C. (2009) Chemostratigraphy-based correlation of Lower Shu'aiba Formation platform sections (Early Aptian, Sultanate of Oman). In: Aptian Stratigraphy and Petroleum Habitat of the Eastern Arabian Plate (Eds F.S.P. van Buchem, M.I. Al-Husseini, F. Maurer and H.J. Droste), 4. GeoArabia Special Publication (in press), Gulf PetroLink, Bahrain. Weissert, H., Lini, A., Föllmi, K.B. and Kuhn, O. (1998) Correlation of Early Cretaceous carbon isotope stratigraphy and platform drowning events: a possible link? Palaeogeography, Palaeoclimatology, Palaeoecology, 137, 189-203.

  10. Multiplicity in Early Stellar Evolution

    Science.gov (United States)

    Reipurth, B.; Clarke, C. J.; Boss, A. P.; Goodwin, S. P.; Rodríguez, L. F.; Stassun, K. G.; Tokovinin, A.; Zinnecker, H.

    Observations from optical to centimeter wavelengths have demonstrated that multiple systems of two or more bodies is the norm at all stellar evolutionary stages. Multiple systems are widely agreed to result from the collapse and fragmentation of cloud cores, despite the inhibiting influence of magnetic fields. Surveys of class 0 protostars with millimeter interferometers have revealed a very high multiplicity frequency of about 2/3, even though there are observational difficulties in resolving close protobinaries, thus supporting the possibility that all stars could be born in multiple systems. Near-infrared adaptive optics observations of class I protostars show a lower binary frequency relative to the class 0 phase, a declining trend that continues through the class II/III stages to the field population. This loss of companions is a natural consequence of dynamical interplay in small multiple systems, leading to ejection of members. We discuss observational consequences of this dynamical evolution, and its influence on circumstellar disks, and we review the evolution of circumbinary disks and their role in defining binary mass ratios. Special attention is paid to eclipsing PMS binaries, which allow for observational tests of evolutionary models of early stellar evolution. Many stars are born in clusters and small groups, and we discuss how interactions in dense stellar environments can significantly alter the distribution of binary separations through dissolution of wider binaries. The binaries and multiples we find in the field are the survivors of these internal and external destructive processes, and we provide a detailed overview of the multiplicity statistics of the field, which form a boundary condition for all models of binary evolution. Finally, we discuss various formation mechanisms for massive binaries, and the properties of massive trapezia.

  11. Near Heterophoria in Early Childhood

    Science.gov (United States)

    Babinsky, Erin; Sreenivasan, Vidhyapriya; Candy, T. Rowan

    2015-01-01

    Purpose. The purpose of this study was to measure near heterophoria in young children to determine the impact of early growth and development on the alignment of the eyes. Methods. Fifty young children (≥2 and accommodation responses, in the absence of optical correction, were measured using simultaneous Purkinje image tracking and photorefraction technology (MCS PowerRefractor, PR). The resulting heterophorias, and both accommodative convergence/accommodation (AC/A) and convergence accommodation/convergence (CA/C) ratios were then computed as a function of age, refractive error, and an alternating cover test. Results. The mean heterophoria after approximately 60 seconds of dissociation at a 33-cm viewing distance was 5.0 prism diopters (pd) of exophoria (SD ± 3.7) in the children (78% of children > 2 pd exophoric) and 5.6 pd of exophoria (SD ± 4.7) in adults (69% of adults > 2pd exophoric; a nonsignificant difference), with no effect of age between 2 and 6 years. In these children, heterophoria was not significantly correlated with AC/A (r = 0.25), CA/C (r = 0.12), or refractive error (r = 0.21). The mean difference between heterophoria measurements from the PR and the clinical cover test was −2.4 pd (SD = ±3.4), with an exophoric bias in the PR measurements. Conclusions. Despite developmental maturation of interpupillary distance, refractive error, and AC/A, in a typical sample of young children the predominant dissociated position is one of exophoria. PMID:25634983

  12. From early wireless to Everest.

    Science.gov (United States)

    Allen, A

    1998-01-01

    Medical information has been transmitted using wireless technologies for almost 80 years. A "wired wireless" electronic stethoscope was developed by the U.S. Army Signal Corps in the early 1920's, for potential use in ship-to-shore transmission of cardiac sounds. [Winters SR. Diagnosis by wireless. Scientific American June 11, 1921, p. 465] Today, wireless is used in a wide range of medical applications and at sites from transoceanic air flights to offshore oil platforms to Mt. Everest. 'Wireless LANs' are often used in medical environments. Typically, nurses and physicians in a hospital or clinic use hand-held "wireless thin client" pen computers that exchange patient information and images with the hospital server. Numerous companies, such as Fujitsu (article below) and Cruise Technologies (www.cruisetech.com) manufacture handheld pen-entry computers. One company, LXE, integrates radio-frequency (RF) enhanced hand-held computers specifically designed for production use within a wireless LAN (www.lxe.com). Other companies (Proxim, Symbol, and others) supply the wireless RF LAN infrastructure for the enterprise. Unfortunately, there have been problems with widespread deployment of wireless LANs. Perhaps the biggest impediment has been the lack of standards. Although an international standard (IEEE 802.11) was adopted in 1997, most wireless LAN products still are not compatible with the equipment of competing companies. A problem with the current standard for LAN adapters is that throughput is limited to 3 Mbps--compared to at least 10 Mbps, and often 100 Mbps, in a hard-wired Ethernet LAN. An II Mbps standard is due out in the next year or so, but it will be at least 2 years before standards-compliant products are available. This story profiles some of the ways that wireless is being used to overcome gaps in terrestrial and within-enterprise communication.

  13. The Early History of Life

    Science.gov (United States)

    Nisbet, E. G.; Fowler, C. M. R.

    2003-12-01

    The youth of the Earth is strange to us. Many of the most fundamental constraints on life may have been different, especially the oxidation state of the surface. Should we suddenly land on its Hadean or early Archean surface by some sci-fi accident, we would not recognize our home. Above, the sky may have been green or some other unworldly color, and above that the weak young Sun might have been unrecognizable to someone trying to identify it from its spectrum. Below, seismology would show a hot, comparatively low-viscosity interior, possibly with a magma ocean in the deeper part of the upper mantle (Drake and Righter, 2002; Nisbet and Walker, 1982), and a core that, though present, was perhaps rather smaller than today. The continents may have been small islands in an icy sea, mostly frozen with some leads of open water, ( Sleep et al., 2001). Into these icy oceans, huge protruding Hawaii-like volcanoes would have poured out vast far-spreading floods of komatiite lavas in immense eruptions that may have created sudden local hypercane storms to disrupt the nearby icebergs. And meteorites would rain down.Or perhaps it was not so strange, nor so violent. The child is father to the man; young Earth was mother to Old Earth. Earth had hydrogen, silicate rock below and on the surface abundant carbon, which her ancient self retains today. Moreover, Earth was oxygen-rich, as today. Today, a tiny part of the oxygen is free, as air; then the oxygen would have been in the mantle while the surface oxygen was used to handcuff the hydrogen as dihydrogen monoxide. Oxygen dihydride is dense, unlikely to fly off to space, and at the poles, rock-forming. Of all the geochemical features that make Earth unique, the initial degassing (Genesis 2 : b) and then the sustained presence of liquid water is the defining oddity of this planet. Early Earth probably also kept much of its carbon, nitrogen, and sulfur as oxide or hydride. And, after the most cataclysmic events had passed, ˜4.5 Ga

  14. REVIEW ARTICLE Conjugated Hyperbilirubinaemia in Early Infancy ...

    African Journals Online (AJOL)

    REVIEW ARTICLE Conjugated Hyperbilirubinaemia in Early Infancy. AOK Johnson. Abstract. Conjugated hyperbilirubinaemia exists when the conjugated serum bilirubin level is more than 2 mg/dl or more than 20 per cent of the total serum bilirubin. It is always pathological in early infancy. The causes are many and diverse ...

  15. Early detection of COPD in general practice

    DEFF Research Database (Denmark)

    Dahl, Ronald; Ulrik, Charlotte Suppli; Løkke, Anders

    2011-01-01

    Early detection enables the possibility for interventions to reduce the future burden of COPD. The Danish National Board of Health recommends that individuals >35 years with tobacco/occupational exposure, and at least 1 respiratory symptom should be offered a spirometry to facilitate early detect...

  16. Problem Solving in the Early Years

    Science.gov (United States)

    Diamond, Lindsay Lile

    2018-01-01

    Problem solving is recognized as a critical component to becoming a self-determined individual. The development of this skill should be fostered in the early years through the use of age-appropriate direct and embedded activities. However, many early childhood teachers may not be providing adequate instruction in this area. This column provides a…

  17. Early Adolescent Sexual Activity: A Developmental Study.

    Science.gov (United States)

    Whitbeck, Les B.; Yoder, Kevin A.; Hoyt, Dan R.; Conger, Rand D.

    1999-01-01

    Examines predictors of early sexual intercourse for a sample of 457 adolescents in grades 8 through 10, from two-parent and single-mother families. Significant decreases were noted in the effect of mother monitoring by 10th grade. The primary predictors of early intercourse were age, opportunity (steady relationship), sexually permissive attitude,…

  18. Early Stuttering, Temperament and Anxiety: Two Hypotheses

    Science.gov (United States)

    Kefalianos, Elaina; Onslow, Mark; Block, Susan; Menzies, Ross; Reilly, Sheena

    2012-01-01

    Purpose: The topic of temperament and early stuttering and the extent to which it involves anxiety is theoretically and clinically relevant. The topic can contribute to theory development and clinical practices with early stuttering. Method: We present a review of the empirical literature for this area with a view to determining which of two…

  19. 37 CFR 1.219 - Early publication.

    Science.gov (United States)

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Early publication. 1.219... COMMERCE GENERAL RULES OF PRACTICE IN PATENT CASES National Processing Provisions Publication of Applications § 1.219 Early publication. Applications that will be published under § 1.211 may be published...

  20. Early Parental Depression and Child Language Development

    Science.gov (United States)

    Paulson, James F.; Keefe, Heather A.; Leiferman, Jenn A.

    2009-01-01

    Objective: To examine the effects of early maternal and paternal depression on child expressive language at age 24 months and the role that parent-to-child reading may play in this pathway. Participants and methods: The 9-month and 24-month waves from a national prospective study of children and their families, the Early Childhood Longitudinal…

  1. The transcriptome landscape of early maize meiosis

    Science.gov (United States)

    Meiosis, particularly meiotic recombination, is a major factor affecting yield and breeding of plants. To gain insight into the transcriptome landscape during early initiation steps of meiotic recombination, we profiled early prophase I meiocytes from maize using RNA-seq. Our analyses of genes prefe...

  2. Early Care in Children with Neurodevelopmental Disorders

    Science.gov (United States)

    Ponce-Meza, Jacqueline

    2017-01-01

    The article analyzes the importance of early care in child development, guiding a neuropsychological perspective of development. The early care model seeks to refer to the set of interventions aimed at children and their work in conjunction with a multidisciplinary team. It presents recommendations for the implementation of programs that allow…

  3. Gender and Boys' Singing in Early Childhood

    Science.gov (United States)

    Hall, Clare

    2005-01-01

    This article derives from a research project investigating the singing behaviour of a group of Australian boys in their first year of school. The project showed that the genesis of the "missing male" trend in singing at school may be occurring in early childhood. The impact of hegemonic masculinity in early childhood is explored here by…

  4. Pretend Play in the Early Childhood Classroom

    Science.gov (United States)

    McEntire, Nancy

    2009-01-01

    This article presents and summarizes recent resources related to pretend play in the early childhood classroom. These include "Contemporary Perspectives on Play in Early Childhood Education" by Olivia N. Sarachoe and Bernard Spodek; "Dramatic Play: Bring It Back" by Tammy Benson; and "The Importance of Being Playful" by Elena Bodrova and Deborah…

  5. Transforming early childhood education for sustainable development

    African Journals Online (AJOL)

    This paper examined the ways in which early childhood education needs to be transformed for sustainable development. These ways include teaching children environmental security through play, personal hygiene, appropriate waste use and disposal, and nature awareness. It was recommended that early childhood ...

  6. Early detection of ecosystem regime shifts

    DEFF Research Database (Denmark)

    Lindegren, Martin; Dakos, Vasilis; Groeger, Joachim P.

    2012-01-01

    methods may have limited utility in ecosystem-based management as they show no or weak potential for early-warning. We therefore propose a multiple method approach for early detection of ecosystem regime shifts in monitoring data that may be useful in informing timely management actions in the face...

  7. Legitimacy and the Value of Early Customers

    NARCIS (Netherlands)

    Wang, Tang; Song, Michael; Zhao, Y. Lisa

    2014-01-01

    To overcome resource constraints and achieve exponential growth, a new venture must rely on early customers of its products to communicate value and commitment to others. For this reason, founders of new ventures focus more on early customers as a key element of their founding strategy than on other

  8. Early-stage mantle cell lymphoma

    DEFF Research Database (Denmark)

    Dabaja, B S; Zelenetz, A D; Ng, A K

    2017-01-01

    Background: Mantle cell lymphoma (MCL) rarely presents as early-stage disease, but clinical observations suggest that patients who present with early-stage disease may have better outcomes than those with advanced-stage disease. Patients and methods: In this 13-institution study, we examined...

  9. Early Childhood Math: Make It Manipulative!

    Science.gov (United States)

    Stone, Janet I.

    1987-01-01

    Maintains that early childhood teachers should provide young children with creative, stimulating, and manipulative (hands-on) experiences rather than workbook pages in early mathematics programs. Presents reasons and corresponding counterpositions for using workbooks and suggests sample activities which teachers can use to make mathematics more…

  10. Early Years Students' Relationships with Mathematics

    Science.gov (United States)

    Takeuchi, Miwa Aoki; Towers, Jo; Plosz, Jennifer

    2016-01-01

    Early years mathematics experiences have been shown to be a significant predictor for students' school readiness and future mathematics achievement. Previous research also indicates an important connection between emotion and mathematics learning. How do students in early years education in Alberta describe their emotional relationship with…

  11. New treatment of early fetal chylothorax

    DEFF Research Database (Denmark)

    Nygaard, Ulrikka; Sundberg, Karin; Nielsen, Henriette Svarre

    2007-01-01

    OBJECTIVE: To evaluate OK-432, a preparation of Streptococcus pyogenes, in the treatment of early fetal chylothorax. METHODS: A prospective study of all fetuses (n=7) with persistent early chylothorax (gestational ages 16-21 weeks) referred to the tertiary center of fetal medicine in Denmark in 2...

  12. Radical surgery for early stage cervical cancer

    NARCIS (Netherlands)

    Derks, M.

    2017-01-01

    Cervical cancer is one of the most common malignancies in women worldwide. Due to an effective screening programme, in the Netherlands cervical cancer is often detected in early stages of disease. For early stage (International Federation of Gynaecology and Obstetrics (FIGO) stage IB/IIA) cervical

  13. Early adolescent music preferences and minor delinquency

    NARCIS (Netherlands)

    ter Bogt, T.F.M.; Keijsers, L.G.M.T.; Meeus, W.H.J.

    2013-01-01

    Objectives: To test Music Marker Theory (MMT) positing that early adolescents’ preferences for nonmainstream types of popular music indicate concurrent and later minor delinquency. Methods: MMT was tested in a 4-year longitudinal study (n = 309). Results: The results showed that early fans of

  14. The EHDI and Early Intervention Connection

    Science.gov (United States)

    Nelson, Lauri; Bradham, Tamala S.; Houston, K. Todd

    2011-01-01

    State coordinators of early hearing detection and intervention (EHDI) programs completed a strengths, weaknesses, opportunities, and threats, or SWOT, analysis that examined 12 areas within state EHDI programs. For the early intervention focus question, 48 coordinators listed 273 items, and themes were identified within each SWOT category. A…

  15. Challenges and limitations in early intervention

    NARCIS (Netherlands)

    Hadders-Algra, Mijna

    Research over the past three decades has shown that early intervention in infants biologically at risk of developmental disorders, irrespective of the presence of a brain lesion, is associated with improved cognitive development in early childhood without affecting motor development. However, at

  16. Early Childhood Education: History, Theory, and Practice

    Science.gov (United States)

    Morgan, Harry

    2006-01-01

    In this book, the author covers the history, theory, and practices that influence early childhood education along with an emphasis on infant and toddler care and education. He also presents a comparison of the conflict between education planners who support early childhood studies and state school systems whose cost-saving measures are dismantling…

  17. Transforming the Early Care and Education Workforce

    Science.gov (United States)

    Vecchiotti, Sara

    2018-01-01

    There is ample opportunity for state boards to improve outcomes for children by strengthening the early care and education workforce and thereby improving the quality of early care and education. Ensuring that ECE professionals have the knowledge, supports, and resources they need to support children's learning is one avenue to improving the…

  18. Early Sport Specialization: A Psychological Perspective

    Science.gov (United States)

    Gould, Daniel

    2010-01-01

    Specializing too early in life can lead to emotional stress, loss of motivation, and burnout, but the research is inadequate to resolve the question of whether early specialization or diversification is more beneficial from a psychological perspective. Nevertheless, some best practices are recommended based on the known benefits and detriments.…

  19. Gene expression in early stage cervical cancer

    NARCIS (Netherlands)

    Biewenga, Petra; Buist, Marrije R.; Moerland, Perry D.; van Thernaat, Emiel Ver Loren; van Kampen, Antoine H. C.; ten Kate, Fiebo J. W.; Baas, Frank

    2008-01-01

    Objective. Pelvic lymph node metastases are the main prognostic factor for survival in early stage cervical cancer, yet accurate detection methods before surgery are lacking. In this study, we examined whether gene expression profiling can predict the presence of lymph node metastasis in early stage

  20. Understanding the Early Years (UEY) Initiative

    Science.gov (United States)

    Human Resources and Social Development Canada, 2007

    2007-01-01

    Internal Audit Services conducted an Early Implementation Review of the Understanding the Early Years (UEY) Initiative in 2006-07. This review is intended to provide assurance to senior management that program delivery has been established appropriately in order to meet its objectives and highlight any areas that require focused management…

  1. The Messinian/Early Pliocene transition in Eastern Mediterranean: New palaeoenvironmental data from the Kalamaki section (Zakynthos Island, Greece)

    Science.gov (United States)

    Drinia, Hara; Antonarakou, Assimina; Tsourou, Theodora; Tzortzaki, Evi; Filippidi, Amalia; Nikolaou, Konstantinos

    2010-05-01

    The purpose of this study is to describe the Miocene-Pliocene microfaunal development, and to discuss its palaeoenvironmental and palaeogeographical significance. The studied section (Kalamaki section) is located in the eastern part of Zakynthos Island (western Greece). Details on lithology and stratigraphy of the section are given in Dermitzakis (1978) and Nikolaou (1986). Planktonic species indicate that sediments span the interval which corresponds to MPL1 Zone (Zanclean, early Pliocene) which is in accordance with the biostratigraphic configuration of Rouchy et al. (1992) and Pierre et al. (2006). The studied interval is characterized by the Sphaeroidinellopsis Acme Zone and the presence of Globorotalia margaritae. The recognized succession of microfossil assemblages serves to interpret the evolution of some palaeoenvironmental factors (waterdepth, salinity and oxygen content), whereas the planktonic foraminiferal zonation allows an age assignment to the events. During the Late Messinian brackish conditions became dominant. The early Pliocene is characterized by a sudden return to well oxygenated, open marine, outer shelf conditions. At the basal part of the record, the high abundance of the 'shallow water component' of the benthic foraminiferal fauna indicates a well-vegetated environment with either normal marine salinity or a tendency to hyposalinity (e.g. Murray, 2006). Open marine conditions are indicated by the diversity of benthic and planktonic foraminifera. The abundance of Lenticulina spp., Cibicidoides pseudoungerianus, Planulina ariminensis, Pullenia, Gyroidina, and the virtual absence of Cibicidoides dutemplei and other typical shelf-taxa, suggest an upper bathyal waterdepth of 300-400 m (cf. Pujos, 1976; Jorissen, 1988). Partly, the abundance of Cibicidoides pseudoungerianus, Bulimina costata and Uvigerina peregrina reflect fluctuations in oxygen content of the bottom waters. However, extreme conditions were never reached during deposition. The

  2. Early dissemination seeds metastasis in breast cancer

    Science.gov (United States)

    Hosseini, Hedayatollah; Obradović, Milan M.S.; Hoffmann, Martin; Harper, Kathryn; Sosa, Maria Soledad; Werner-Klein, Melanie; Nanduri, Lahiri Kanth; Werno, Christian; Ehrl, Carolin; Maneck, Matthias; Patwary, Nina; Haunschild, Gundula; Gužvić, Miodrag; Reimelt, Christian; Grauvogl, Michael; Eichner, Norbert; Weber, Florian; Hartkopf, Andreas; Taran, Florin-Andrei; Brucker, Sara Y.; Fehm, Tanja; Rack, Brigitte; Buchholz, Stefan; Spang, Rainer; Meister, Gunter; Aguirre-Ghiso, Julio A.; Klein, Christoph A.

    2016-01-01

    Accumulating data suggest that metastatic dissemination often occurs early during tumour formation but the mechanisms of early metastatic spread have not yet been addressed. Here, we studied metastasis in a HER2-driven mouse breast cancer model and found that progesterone-induced signalling triggered migration of cancer cells from early lesions shortly after HER2 activation, but promoted proliferation in advanced primary tumour cells. The switch from migration to proliferation was regulated by elevated HER2 expression and increased tumour cell density involving miRNA-mediated progesterone receptor (PGR) down-regulation and was reversible. Cells from early, low-density lesions displayed more stemness features than cells from dense, advanced tumours, migrated more and founded more metastases. Strikingly, we found that at least 80% of metastases were derived from early disseminated cancer cells (DCC). Karyotypic and phenotypic analysis of human disseminated cancer cells and primary tumours corroborated the relevance of these findings for human metastatic dissemination. PMID:27974799

  3. Validation of the Early Functional Abilities scale

    DEFF Research Database (Denmark)

    Poulsen, Ingrid; Kreiner, Svend; Engberg, Aase W

    2018-01-01

    model item analysis. A secondary objective was to examine the relationship between the Early Functional Abilities scale and the Functional Independence Measurement™, in order to establish the criterion validity of the Early Functional Abilities scale and to compare the sensitivity of measurements using......), facio-oral, sensorimotor and communicative/cognitive functions. Removal of one item from the sensorimotor scale confirmed unidimensionality for each of the 4 subscales, but not for the entire scale. The Early Functional Abilities subscales are sensitive to differences between patients in ranges in which......OBJECTIVE: The Early Functional Abilities scale assesses the restoration of brain function after brain injury, based on 4 dimensions. The primary objective of this study was to evaluate the validity, objectivity, reliability and measurement precision of the Early Functional Abilities scale by Rasch...

  4. Bolatu's pharmacy theriac in early modern China.

    Science.gov (United States)

    Nappi, Carla

    2009-01-01

    In early modem China, natural history and medicine were shifting along with the boundaries of the empire. Naturalists struggled to cope with a pharmacy's worth of new and unfamiliar substances, texts, and terms, as plants, animals, and the drugs made from them travelled into China across land and sea. One crucial aspect of this phenomenon was the early modern exchange between Islamic and Chinese medicine. The history of theriac illustrates the importance of the recipe for the naturalization of foreign objects in early modem Chinese medicine. Theriac was a widely sought-after and hotly debated product in early modern European pharmacology and arrived into the Chinese medical canon via Arabic and Persian texts. The dialogue between language and material objects was critical to the Silk Road drug trade, and transliteration was ultimately a crucial technology used to translate drugs and texts about them in the early modern world.

  5. Screening of colorectal early cancer by radiology

    International Nuclear Information System (INIS)

    Matsukawa, M.; Usui, Y.; Kobayashi, S.

    1988-01-01

    The incidence of colorectal cancer has been gradually increasing in Japan, and if the present rate of increase is maintained it has been estimated that it will become the most common of all malignant neoplasms by the year 2000. It has been proved that colorectal cancer can be completely cured, if it is treated in its early phase. Early cancer of the large bowel is defined as a cancer which is limited to the mucosal membrane or submucosal layer, regardless of lymph node and distant metastases. Detection of early cancer improves the overall curability of colorectal cancer. The greatest number of early cancers of the large bowel are polypoid lesions in their macroscopic form, and depressed lesions are rarely encountered. Accordingly, the first step in the detection of early cancer starts with the screening of polypoid lesion by radiology and endoscopy. This paper is concerned with diagnostic accuracy of radiology in the screening of colorectal cancer with endoscopic correlation

  6. Sophisticated digestive systems in early arthropods.

    Science.gov (United States)

    Vannier, Jean; Liu, Jianni; Lerosey-Aubril, Rudy; Vinther, Jakob; Daley, Allison C

    2014-05-02

    Understanding the way in which animals diversified and radiated during their early evolutionary history remains one of the most captivating of scientific challenges. Integral to this is the 'Cambrian explosion', which records the rapid emergence of most animal phyla, and for which the triggering and accelerating factors, whether environmental or biological, are still unclear. Here we describe exceptionally well-preserved complex digestive organs in early arthropods from the early Cambrian of China and Greenland with functional similarities to certain modern crustaceans and trace these structures through the early evolutionary lineage of fossil arthropods. These digestive structures are assumed to have allowed for more efficient digestion and metabolism, promoting carnivory and macrophagy in early arthropods via predation or scavenging. This key innovation may have been of critical importance in the radiation and ecological success of Arthropoda, which has been the most diverse and abundant invertebrate phylum since the Cambrian.

  7. Long-term Consequences of Early Parenthood

    DEFF Research Database (Denmark)

    Johansen, Eva Rye; Nielsen, Helena Skyt; Verner, Mette

    (and to lesser extent employment), as fathers appear to support the family, especially when early parenthood is combined with cohabitation with the mother and the child. Heterogeneous effects reveal that individuals with a more favorable socioeconomic background are affected more severely than......Having children at an early age is known to be associated with unfavorable economic outcomes, such as lower education, employment and earnings. In this paper, we study the long-term consequences of early parenthood for mothers and fathers. Our study is based on rich register-based data that......, importantly, merges all childbirths to the children’s mothers and fathers, allowing us to study the consequences of early parenthood for both parents. We perform a sibling fixed effects analysis in order to account for unobserved family attributes that are possibly correlated with early parenthood...

  8. Diastolic and autonomic dysfunction in early cirrhosis

    DEFF Research Database (Denmark)

    Dahl, Emilie Kristine; Møller, Søren; Kjær, Andreas

    2014-01-01

    OBJECTIVE. Presence of cardiac dysfunction in patients with advanced cirrhosis is widely accepted, but data in early stages of cirrhosis are limited. Systolic and diastolic functions, dynamics of QT-interval, and pro-atrial natriuretic peptide (pro-ANP) are investigated in patients with early stage...... cirrhosis during maximal β-adrenergic drive. MATERIAL AND METHODS. Nineteen patients with Child A (n = 12) and Child B cirrhosis (n = 7) and seven matched controls were studied during cardiac stress induced by increasing dosages of dobutamine and atropine. RESULTS. Pharmacological responsiveness was similar...... indicate that patients with early stage cirrhosis exhibit early diastolic and autonomic dysfunction as well as elevated pro-ANP. However, the cardiac chronotropic and inotropic responses to dobutamine stress were normal. The dynamics of ventricular repolarization appears normal in patients with early stage...

  9. The Association between Early Conduct Problems and Early Marijuana Use in College Students

    Science.gov (United States)

    Falls, Benjamin J.; Wish, Eric D.; Garnier, Laura M.; Caldeira, Kimberly M.; O'Grady, Kevin E.; Vincent, Kathryn B.; Arria, Amelia M.

    2011-01-01

    Early conduct problems have been linked to early marijuana use in adolescence. The present study examines this association in a sample of 1,076 college students that was divided into three groups: (1) early marijuana users (began marijuana use prior to age 15; N = 126), (2) late marijuana users (began marijuana use at or after age 15; N = 607),…

  10. Early Childhood Educators' Perceived and Actual Metalinguistic Knowledge, Beliefs and Enacted Practice about Teaching Early Reading

    Science.gov (United States)

    Hammond, Lorraine

    2015-01-01

    Results of influential reports on early literacy have drawn attention to the need for early childhood educators to take up a more explicit, teacher-directed approach to beginning reading. Positive classroom results however are in part dependent upon teacher knowledge and this study investigated the relationship between early childhood educators'…

  11. Climate, vegetation and lake development at Sokli (northern Finland) during early MIS 3 at approx50 kyr: Revising earlier concepts on climate, glacial and vegetation dynamics in Fennoscandia during the Weichselian

    Energy Technology Data Exchange (ETDEWEB)

    Helmens, Karin F. (Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden))

    2009-08-15

    Long sediment records that register environmental changes in formerly glaciated regions such as Fennoscandia in the period preceding the Last Glacial Maximum (LGM) at approx 20 kyr are rare. The Weichselian history of Fennoscandia is based on the long-distance correlation of poorly dated stratigraphic fragmentary evidence and studies on glacial geomorphology. Environmental conditions during ice-free intervals have been mostly reconstructed based on low resolution palynological analysis only. Here we present the results of a detailed study of a for Fennoscandia unusually long and continuous sediment sequence that has been recovered from the Sokli basin in northern Finland. The Sokli sequence consists of tills, glacio-fluvial beds, and fluvial beds, interlayered with fossil-rich lacustrine sediments that according to multiple accelerator mass spectrometer (AMS) 14C and optically stimulated luminescence (OSL) datings extend from the present into the Penultimate Glacial representing the last approx130 kyr. This report focuses on the youngest Weichselian interstadial interval with ice-free conditions at Sokli dated to approx50 kyr in the early part of Marine Isotope Stage (MIS) 3. A comprehensive environmental reconstruction is made based on multi-proxy analysis on a two meter thick laminated, lacustrine clay-silt sequence, including lithological characteristics; organic content (loss-on-ignition, LOI); plant microfossils (pollen, spores, algal and fungal remains); macrofossils of plants (e.g. seeds, moss remains) and of aquatic animals (e.g. statoblasts of Bryozoa); head-capsules of chironomids (i.e. aquatic insects); and diatoms and other siliceous microfossils (e.g. phytolits, chrysophyte stomatocysts). Additionally, geomorphic evidence and analysis of Digital Elevation Model (DEM) data are employed in the environmental reconstruction. Mean July temperatures are reconstructed by applying transfer functions to the pollen, chironomid and diatom records. The results

  12. Climate, vegetation and lake development at Sokli (northern Finland) during early MIS 3 at ∼50 kyr: Revising earlier concepts on climate, glacial and vegetation dynamics in Fennoscandia during the Weichselian

    International Nuclear Information System (INIS)

    Helmens, Karin F.

    2009-08-01

    Long sediment records that register environmental changes in formerly glaciated regions such as Fennoscandia in the period preceding the Last Glacial Maximum (LGM) at ∼ 20 kyr are rare. The Weichselian history of Fennoscandia is based on the long-distance correlation of poorly dated stratigraphic fragmentary evidence and studies on glacial geomorphology. Environmental conditions during ice-free intervals have been mostly reconstructed based on low resolution palynological analysis only. Here we present the results of a detailed study of a for Fennoscandia unusually long and continuous sediment sequence that has been recovered from the Sokli basin in northern Finland. The Sokli sequence consists of tills, glacio-fluvial beds, and fluvial beds, interlayered with fossil-rich lacustrine sediments that according to multiple accelerator mass spectrometer (AMS) 14 C and optically stimulated luminescence (OSL) datings extend from the present into the Penultimate Glacial representing the last ∼130 kyr. This report focuses on the youngest Weichselian interstadial interval with ice-free conditions at Sokli dated to ∼50 kyr in the early part of Marine Isotope Stage (MIS) 3. A comprehensive environmental reconstruction is made based on multi-proxy analysis on a two meter thick laminated, lacustrine clay-silt sequence, including lithological characteristics; organic content (loss-on-ignition, LOI); plant microfossils (pollen, spores, algal and fungal remains); macrofossils of plants (e.g. seeds, moss remains) and of aquatic animals (e.g. statoblasts of Bryozoa); head-capsules of chironomids (i.e. aquatic insects); and diatoms and other siliceous microfossils (e.g. phytolits, chrysophyte stomatocysts). Additionally, geomorphic evidence and analysis of Digital Elevation Model (DEM) data are employed in the environmental reconstruction. Mean July temperatures are reconstructed by applying transfer functions to the pollen, chironomid and diatom records. The results have been

  13. Early onset depression: the relevance of anxiety.

    Science.gov (United States)

    Parker, G; Wilhelm, K; Asghari, A

    1997-01-01

    The aim of this study was to determine risk factors that may differentiate early onset from late onset depression. A non-clinical cohort that had been assessed from 1978 to 1993 at 5 yearly intervals and that had a high prevalence rate of lifetime depression took part in the study. We established an appropriate age cut-off to distinguish early onset (i.e. before 26 years) of major and of minor depression, and examined the relevance of a number of possible determinants of early onset depression assessed over the life of the study. Despite several dimensional measures of depression, self-esteem and personality being considered, they generally failed (when assessed early in the study) to discriminate subsequent early onset depression, with the exception of low masculinity scores being a weak predictor of major and/or minor depression. Early onset depression was strongly predicted, however, by a lifetime episode of a major anxiety disorder, with generalised anxiety being a somewhat stronger and more consistent predictor than panic disorder, agoraphobia and minor anxiety disorders (ie social phobia, simple phobia). The possibility that anxiety may act as a key predispositional factor to early onset depression and to a greater number of depressive episodes is important in that clinical assessment and treatment of any existing anxiety disorder may be a more efficient and useful strategy than focussing primarily on the depressive disorder.

  14. Penetrative trace fossils from the late Ediacaran of Mongolia: early onset of the agronomic revolution

    Science.gov (United States)

    Oji, Tatsuo; Dornbos, Stephen Q.; Yada, Keigo; Hasegawa, Hitoshi; Gonchigdorj, Sersmaa; Mochizuki, Takafumi; Takayanagi, Hideko; Iryu, Yasufumi

    2018-02-01

    The Cambrian radiation of complex animals includes a dramatic increase in the depth and intensity of bioturbation in seafloor sediment known as the `agronomic revolution'. This bioturbation transition was coupled with a shift in dominant trace fossil style from horizontal surficial traces in the late Precambrian to vertically penetrative trace fossils in the Cambrian. Here we show the existence of the first vertically penetrative trace fossils from the latest Ediacaran: dense occurrences of the U-shaped trace fossil Arenicolites from late Precambrian marine carbonates of Western Mongolia. Their Ediacaran age is established through stable carbon isotope chemostratigraphy and their occurrence stratigraphically below the first appearance of the trace fossil Treptichnus pedum. These Arenicolites are large in diameter, penetrate down to at least 4 cm into the sediment, and were presumably formed by the activity of bilaterian animals. They are preserved commonly as paired circular openings on bedding planes with maximum diameters ranging up to almost 1 cm, and as U- and J-shaped tubes in vertical sections of beds. Discovery of these complex penetrative trace fossils demonstrates that the agronomic revolution started earlier than previously considered.

  15. [Treatment of early stage Hodgkin disease

    DEFF Research Database (Denmark)

    Specht, Lena; Carde, P.; Mauch, P.

    1993-01-01

    indicate that we still do not definitively know whether or not the early addition of prophylactic chemotherapy improves survival. Arguments in favour of early chemotherapy are: that laparotomy may be avoided, that radiation fields and doses may perhaps be reduced, and that the stress of experiencing...... a relapse is avoided in many patients. The major argument against early chemotherapy is: that by careful staging and selection of patients and by careful radiotherapy techniques the number of patients exposed to potentially toxic chemotherapy may be kept at a minimum. Recently, trials have been carried out...

  16. The determinants of early retirement in Switzerland

    OpenAIRE

    Dorn, David; Sousa-Poza, Alfonso

    2005-01-01

    In the past decade, Switzerland has experienced a large increase in the number of individuals going into early retirement. This paper examines the determinants of such early retirement using data from the newly implemented social-security module of the 2002 Swiss Labor Force Survey. In the sixteen-month period from January 2001 to April 2002, more than 36,000 older individuals, representing 8% of all workers within nine years of legal retirement age, became early retirees. One of the most imp...

  17. Diagnosis of early stomach cancer (Lecture)

    International Nuclear Information System (INIS)

    Vinner, M.G.

    1989-01-01

    Problems concerning diagnosis of early stomach cancer using X-ray and endoscopic investigation techniques are stated. Classification of early stomach cancer suggested by the Japan Endoscopy Society and division system of early stomach cancer into two main foms: depth (erosive-ulcerous) one and elevated (polypoid) one-is presented X-ray and endoscopic investigation techniques are shown to be high efficiency concerning revealingation of stomach mucous variations using biopsy, which allow to determine for certain whother the process is benign or malignant one

  18. Selective phosphorylation during early macrophage differentiation

    KAUST Repository

    Zhang, Huoming; Qian, Pei-Yuan; Ravasi, Timothy

    2015-01-01

    -regulated phosphoproteins in the early stages of differentiation. Further analysis of the PMA-regulated phosphoproteins revealed that transcriptional suppression, cytoskeletal reorganization and cell adhesion were among the most significantly activated pathways. Some key

  19. Subcortical functional reorganization due to early blindness.

    Science.gov (United States)

    Coullon, Gaelle S L; Jiang, Fang; Fine, Ione; Watkins, Kate E; Bridge, Holly

    2015-04-01

    Lack of visual input early in life results in occipital cortical responses to auditory and tactile stimuli. However, it remains unclear whether cross-modal plasticity also occurs in subcortical pathways. With the use of functional magnetic resonance imaging, auditory responses were compared across individuals with congenital anophthalmia (absence of eyes), those with early onset (in the first few years of life) blindness, and normally sighted individuals. We find that the superior colliculus, a "visual" subcortical structure, is recruited by the auditory system in congenital and early onset blindness. Additionally, auditory subcortical responses to monaural stimuli were altered as a result of blindness. Specifically, responses in the auditory thalamus were equally strong to contralateral and ipsilateral stimulation in both groups of blind subjects, whereas sighted controls showed stronger responses to contralateral stimulation. These findings suggest that early blindness results in substantial reorganization of subcortical auditory responses. Copyright © 2015 the American Physiological Society.

  20. Early ontogeny of Labeo capensis (pisces: Cyprinidae)

    African Journals Online (AJOL)

    the early development of Indian Labeo species (e.g. Khan. 1925; Ahmad 1944 ...... ber, size or intensity, was helpful in grouping North American cyprinid larvae. .... impregnated eggs of common freshwater fishes of Bengal. Curro Sci. 26: 125 ...