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Sample records for late ordovician rugose

  1. NEW INFORMATION ON LATE ORDOVICIAN AND EARLY SILURIAN RUGOSE CORALS IN NORTHERN GUIZHOU PROVINCE%黔北晚奥陶世和早志留世四射珊瑚新资料

    Institute of Scientific and Technical Information of China (English)

    何心一; 陈建强

    2003-01-01

    报道黔北早志留世中期(Middle Llandovery)地层中新发现的四射珊瑚7属--Cantrillia,Neocantrillia,Prototryplasma,Pycnostylus, Dalmanophyllum?,Rhegmaphyllum, Schlotheimophyllum,并描述产自黔东北石阡奥陶纪末期(Late Ashgill)观音桥层四射珊瑚2种--Grewingkia cf. bilateralis Neuman, Brachyelasma cf. medioseptatum(Neuman)及晚奥陶世(Early Ashgill期)涧草沟组中首次发现的四射珊瑚Crassilasma sp..全文共描述四射珊瑚13属18种,其中6新种,它们是 Crassilasma fenggangense sp. nov., C. crebrumseptatum sp. nov., Dinophyllum insolitum sp. nov., Neocantrillia silurica sp. nov., Prototryplasma guizhouense sp. nov., Schlotheimophyllum regeneranum sp. nov..%7 genera of rugose corals are reported from the middle Llandovery in northern Guizhou Province of China for the first time. They are Cantrillia,Neocantrillia,Prototryplasma,Pycnostylus,Dalmanophyllum?, Rhegmaphyllum and Schlotheimophyllum. In addition, two species(Grewingkia cf. bilateralis(Neuman) and Brachyelasma cf. medioseptatum(Neuman) ) collected from the late Ashgill Guanyinqiao Beds in the Shiqian County of northern Guizhou Province, and one species(Crassilasma sp.)from the early Ashgill Jiancaogou (Jiantsaohou) Formation in the same area are described. These data enrich further the content of the Late Ordovician and Early Silurian rugose coral fauna in Yangtze region, and are considerably significant for study on origin, evolution and disperse of some Early Paleozoic rugose corals. Altogether 18 species assigned to 13 genera are described. Among them 6 species are new. They are Crassilasma fenggangense sp. nov., C. crebrumseptatum sp. nov., Dinophyllum insolitum sp. nov., Neocantrillia silurica sp. nov., Prototryplasma guizhouense sp. nov., and Schlotheimophyllum regeneranum sp. nov.

  2. ORIGIN,DISPERSAL AND BIOGEOGRAPHIC AFFINITY OF THE MIDDLE-LATE ORDOVICIAN AND THE LLANDOVERY RUGOSE CORALS IN THE YANGTZE REGION%扬子区中、晚奥陶世和兰多维利世四射珊瑚起源、扩散及生物古地理关系

    Institute of Scientific and Technical Information of China (English)

    何心一; 陈建强

    2004-01-01

    The Middle Ordovician Llandovery rugose corals are abundant in the Yangtze region, especially in the Early Silurian. Altogether 123 genera of Rugosa,which contain 4 genera of Middle Ordovician,25 genera of Late Ordovician,and 94 genera of Llandovery respectively,have been reported from this region, of which 30 genera first appeared in the Yangtze region and then dispersed to Europe and North America and other adjacent regions. The following may represent the earliest occurrence age of the referred genera. Calostylis in the Middle Ordovician(Llandeilo)of southern Sichuan; Aphyllum and Cantrillia in the middle Ashgill of western Zhejiang; the streptelasmatids Briantelasma, Pycnactis and Tunguselasma in the late Ruddanian of northeastern Guizhou; the columnariids Ceriaster, Stauria, Amplexoides and Synamplexoides , and the cystiphyllids Maikottia, Rhizophyllum among others in the Middle Llandovery of northeastern Guizhou, South China. Based on these data, We may regard that the Yangtze region may have been one of the origin centers for the Ordovician and Silurian rugose corals. This paper deals with the Middle Ordovician to Llandovery rugose coral faunas in the Yangtze region, especially with their palaeobiogeographic affinities. The Middle Ordovician Rugosa of this region is characterized by the calostylids Calostylis and Yohophyllum . The Late Ordovician (mid Ashgill) rugosan fauna from the Sanjushan Formation of western Zhejiang Province contains some Australian elements (Hillophyllum, Bowanophyllum) , while the late Ashgill rugose fauna from the Guanyinqiao Bed in the Upper Yangtze region shows a high degree of similarity to that of North Europe, indicating that Yangtze and Europe have a close pala eobiogeographic affinity with each other. The Llandovery rugose fauna in the Yangtze region is much closer with that of Siberia, Kazakhstan and Australia.%扬子区中奥陶世-志留纪兰多维利世四射珊瑚产出丰富,尤以兰多维利世

  3. Phylogenetic paleobiogeography of Late Ordovician Laurentian brachiopods

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    Jennifer E. Bauer

    2014-12-01

    Full Text Available Phylogenetic biogeographic analysis of four brachiopod genera was used to uncover large-scale geologic drivers of Late Ordovician biogeographic differentiation in Laurentia. Previously generated phylogenetic hypotheses were converted into area cladograms, ancestral geographic ranges were optimized and speciation events characterized as via dispersal or vicariance, when possible. Area relationships were reconstructed using Lieberman-modified Brooks Parsimony Analysis. The resulting area cladograms indicate tectonic and oceanographic changes were the primary geologic drivers of biogeographic patterns within the focal taxa. The Taconic tectophase contributed to the separation of the Appalachian and Central basins as well as the two midcontinent basins, whereas sea level rise following the Boda Event promoted interbasinal dispersal. Three migration pathways into the Cincinnati Basin were recognized, which supports the multiple pathway hypothesis for the Richmondian Invasion.

  4. Did intense volcanism trigger the first Late Ordovician icehouse?

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    Buggisch, Werner; Joachimski, Michael M.; Lehnert, Oliver; Bergström, Stig M.; Repetski, John E.; Webers, Gerald F.

    2010-01-01

    Oxygen isotopes measured on Late Ordovician conodonts from Minnesota and Kentucky (United States) were studied to reconstruct the paleotemperature history during late Sandbian to Katian (Mohawkian–Cincinnatian) time. This time interval was characterized by intense volcanism, as shown by the prominent Deicke, Millbrig, and other K-bentonite beds. A prominent carbon isotope excursion (Guttenberg δ13C excursion, GICE) postdates the Millbrig volcanic eruptions, and has been interpreted to reflect a drawdown of atmospheric carbon dioxide and climatic cooling. The oxygen isotope record in conodont apatite contradicts this earlier interpretation. An increase in δ18O of 1.5‰ (Vienna standard mean ocean water) just above the Deicke K-bentonite suggests an abrupt and short-lived cooling that possibly initiated a first short-term glacial episode well before the major Hirnantian glaciation. The decrease in δ18O immediately after the mega-eruptions indicates warming before the GICE, and no cooling is shown in the GICE interval. The coincidence of the Deicke mega-eruption with a cooling event suggests that this major volcanic event had a profound effect on Late Ordovician (late Mohawkian) climate.

  5. The Late Ordovician deglaciation sequence of the SW Murzuq Basin (Libya)

    DEFF Research Database (Denmark)

    Moreau, Julien

    2011-01-01

    Rocks of Late Ordovician to Silurian age are well exposed on the western rim of theMurzuq Basin (Ghat-Tikiumit area,Libya)where seismic-scale exposures allow spectacular insights into the growth and decay of the LateOrdovician (Hirnantian) ice sheet.The ¢nal deglaciation left a complex topography...

  6. The onset of the 'Ordovician Plankton Revolution' in the late Cambrian

    DEFF Research Database (Denmark)

    Servais, Thomas; Perrier, Vincent; Danelian, Taniel

    2016-01-01

    The 'Great Ordovician Biodiversification Event' comprises the rapid diversification of marine organisms during the Ordovician Period. It is now clear that this adaptive radiation started for some organisms already in the Cambrian and continued for others beyond the end of the Ordovician, making...... during the late Cambrian and Early Ordovician, in particular in relation to the SPICE event. Our analyses include the changing diversities of the phytoplankton (acritarchs), diverse groups of zooplankton (e.g., radiolarians, graptolites, chitinozoans) and the switch to a planktonic mode of life of fossil...

  7. High potential for weathering and climate effects of non-vascular vegetation in the Late Ordovician

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    Porada, P.; Lenton, T. M.; Pohl, A.; Weber, B.; Mander, L.; Donnadieu, Y.; Beer, C.; Pöschl, U.; Kleidon, A.

    2016-07-01

    It has been hypothesized that predecessors of today's bryophytes significantly increased global chemical weathering in the Late Ordovician, thus reducing atmospheric CO2 concentration and contributing to climate cooling and an interval of glaciations. Studies that try to quantify the enhancement of weathering by non-vascular vegetation, however, are usually limited to small areas and low numbers of species, which hampers extrapolating to the global scale and to past climatic conditions. Here we present a spatially explicit modelling approach to simulate global weathering by non-vascular vegetation in the Late Ordovician. We estimate a potential global weathering flux of 2.8 (km3 rock) yr-1, defined here as volume of primary minerals affected by chemical transformation. This is around three times larger than today's global chemical weathering flux. Moreover, we find that simulated weathering is highly sensitive to atmospheric CO2 concentration. This implies a strong negative feedback between weathering by non-vascular vegetation and Ordovician climate.

  8. Phylogenetic Clustering of Origination and Extinction across the Late Ordovician Mass Extinction.

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    Andrew Z Krug

    Full Text Available Mass extinctions can have dramatic effects on the trajectory of life, but in some cases the effects can be relatively small even when extinction rates are high. For example, the Late Ordovician mass extinction is the second most severe in terms of the proportion of genera eliminated, yet is noted for the lack of ecological consequences and shifts in clade dominance. By comparison, the end-Cretaceous mass extinction was less severe but eliminated several major clades while some rare surviving clades diversified in the Paleogene. This disconnect may be better understood by incorporating the phylogenetic relatedness of taxa into studies of mass extinctions, as the factors driving extinction and recovery are thought to be phylogenetically conserved and should therefore promote both origination and extinction of closely related taxa. Here, we test whether there was phylogenetic selectivity in extinction and origination using brachiopod genera from the Middle Ordovician through the Devonian. Using an index of taxonomic clustering (RCL as a proxy for phylogenetic clustering, we find that A both extinctions and originations shift from taxonomically random or weakly clustered within families in the Ordovician to strongly clustered in the Silurian and Devonian, beginning with the recovery following the Late Ordovician mass extinction, and B the Late Ordovician mass extinction was itself only weakly clustered. Both results stand in stark contrast to Cretaceous-Cenozoic bivalves, which showed significant levels of taxonomic clustering of extinctions in the Cretaceous, including strong clustering in the mass extinction, but taxonomically random extinctions in the Cenozoic. The contrasting patterns between the Late Ordovician and end-Cretaceous events suggest a complex relationship between the phylogenetic selectivity of mass extinctions and the long-term phylogenetic signal in origination and extinction patterns.

  9. High potential for weathering and climate effects of non-vascular vegetation in the Late Ordovician

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    Porada, Philipp; Lenton, Tim; Pohl, Alexandre; Weber, Bettina; Mander, Luke; Donnadieu, Yannick; Beer, Christian; Pöschl, Ulrich; Kleidon, Axel

    2017-04-01

    Early non-vascular vegetation in the Late Ordovician may have strongly increased chemical weathering rates of surface rocks at the global scale. This could have led to a drawdown of atmospheric CO2 and, consequently, a decrease in global temperature and an interval of glaciations. Under current climatic conditions, usually field or laboratory experiments are used to quantify enhancement of chemical weathering rates by non-vascular vegetation. However, these experiments are constrained to a small spatial scale and a limited number of species. This complicates the extrapolation to the global scale, even more so for the geological past, where physiological properties of non-vascular vegetation may have differed from current species. Here we present a spatially explicit modelling approach to simulate large-scale chemical weathering by non-vascular vegetation in the Late Ordovician. For this purpose, we use a process-based model of lichens and bryophytes, since these organisms are probably the closest living analogue to Late Ordovician vegetation. The model explicitly represents multiple physiological strategies, which enables the simulated vegetation to adapt to Ordovician climatic conditions. We estimate productivity of Ordovician vegetation with the model, and relate it to chemical weathering by assuming that the organisms dissolve rocks to extract phosphorus for the production of new biomass. Thereby we account for limits on weathering due to reduced supply of unweathered rock material in shallow regions, as well as decreased transport capacity of runoff for dissolved weathered material in dry areas. We simulate a potential global weathering flux of 2.8 km3 (rock) per year, which we define as volume of primary minerals affected by chemical transformation. Our estimate is around 3 times larger than today's global chemical weathering flux. Furthermore, chemical weathering rates simulated by our model are highly sensitive to atmospheric CO2 concentration, which implies

  10. Crouching shells, hidden sponges: Unusual Late Ordovician cavities containing sponges

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    Park, Jino; Lee, Jeong-Hyun; Hong, Jongsun; Choh, Suk-Joo; Lee, Dong-Chan; Lee, Dong-Jin

    2017-01-01

    Marine cavities harbouring cryptic organisms have been ubiquitous throughout the Phanerozoic. However, our knowledge of early cryptic communities is as yet insufficient, and how metazoans began to utilize such habitats remains unknown. In this study, we document demosponge remains within intraskeletal cavities embedded in the micritic succession of a shallow carbonate platform in the Upper Ordovician (Katian) Xiazhen Formation of South China. Molluscs (gastropods, bivalves, and nautiloids) and corals (the solitary rugosan Tryplasma and colonial agetolitids) within the succession commonly contain patches of "spicular" demosponge remains (11%; n = 45/415), mainly occupying intraskeletal spaces with areas of 1-30 mm2 in thin-section. Sponge occurrence varies according to sedimentary facies: within lime mudstone facies, sponges commonly occur both inside and outside intraskeletal cavities, suggesting that sponges would have inhabited and become preserved within any available space in this environment. In contrast, when other sessile organisms co-occur in wackestone to packstone facies, there are fewer sponge occurrences both inside and outside cavities, possibly due to competition in open habitats and/or their poorer preservation in such environments. Overall, this result suggests that sponges would have exploited cryptic habitats by normal expansion of the open-surface biota. In addition, compared with coeval reef and hardground crypts, the Xiazhen intraskeletal cryptic biota is monotonous in composition, suggesting "decoupled" occupation of cryptic habitats in different environments.

  11. Biogeographic and bathymetric determinants of brachiopod extinction and survival during the Late Ordovician mass extinction

    DEFF Research Database (Denmark)

    Finnegan, Seth; Mac Ørum Rasmussen, Christian; Harper, David A. T.

    2016-01-01

    The Late Ordovician mass extinction (LOME) coincided with dramatic climate changes, but there are numerous ways in which these changes could have driven marine extinctions. We use a palaeobiogeographic database of rhynchonelliform brachiopods to examine the selectivity of Late Ordovician......–Early Silurian genus extinctions and evaluate which extinction drivers are best supported by the data. The first (latest Katian) pulse of the LOME preferentially affected genera restricted to deeper waters or to relatively narrow (less than 35°) palaeolatitudinal ranges. This pattern is only observed...... in the latest Katian, suggesting that it reflects drivers unique to this interval. Extinction of exclusively deeper-water genera implies that changes in water mass properties such as dissolved oxygen content played an important role. Extinction of genera with narrow latitudinal ranges suggests that interactions...

  12. Late Ordovician-Early Silurian chitinozoans from north-eastern and western Illinois, USA

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    Butcher, A.; Mikulic, Donald G.; Kluessendorf, Joanne

    2010-01-01

    Samples of uppermost Ordovician and Silurian strata from two cores from north-eastern and western Illinois were processed for chitinozoans. Due to apparent sea-floor oxidation or palaeoenvironmental constraints, very few samples yielded specimens, but those that did allow tentative correlation with established biostratigraphical zonations for the Chitinozoa. Samples from the Wilhelmi Formation of core DH76-21 in north-eastern Illinois yielded Spinachitina fragilis, a typically earliest Silurian taxon. A sample from the Maquoketa Group strata of core Principia #4, western Illinois, yielded a monospecific assemblage of Conochitina elegans, which is suggestive of a late Ordovician age. Higher in this core, a sample from the upper strata of the Bowling Green Dolomite yielded an assemblage indicating a late Rhuddanian to Aeronian age, including Angochitina hansonica, previously only described from strata in Nevada, and one new species, Fungochitina illinoisensis. ?? 2009 Elsevier B.V. All rights reserved.

  13. Complexity in benthic-pelagic marine ecosystems in the late Ordovician (central New York)

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, S.M.

    1985-01-01

    Cisne and Chandlee (1982) outlined a paleogeographic model for marine invertebrates collected from Middle Ordovician strata in central New York. Subsequent interpretations of their stratigraphic and geographic distributions were based on control by levels of oxygen. Especially critical were the presumed distribution of the trilobite Triarthus and three graptolites, Orthograptus, Climacograptus, and Corynoides, which were supposed to have occupied vertically stratified habitats in the water column. In order to test this general thesis 42 stratigraphically discrete samples were collected from continuously exposed Late Ordovician mudstones in central New York, which contained taxa virtually identically to those employed by Cisne. The sampling interval spanned about 1.5 million years and over 1/4 of the samples contained relatively large numbers of graptolites. Over 3000 graptolite rhabdosomes were identified. The later Ordovician Orthograptus are preserved both with and without Climacograptus and with various benthic taxa. However neither Orthograptus nor Climacograptus display a consistent stratigraphic pattern, and Triarthus co-occurred with both graptolites, introducing a discordant note into any attempt at a simple modeling of early Paleozoic benthic/pelagic ecosystems.

  14. Marine ostracod provinciality in the Late Ordovician of palaeocontinental Laurentia and its environmental and geographical expression.

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    Mohibullah Mohibullah

    Full Text Available BACKGROUND: We examine the environmental, climatic and geographical controls on tropical ostracod distribution in the marine Ordovician of North America. METHODOLOGY/PRINCIPAL FINDINGS: Analysis of the inter-regional distribution patterns of Ordovician Laurentian ostracods, focussing particularly on the diverse Late Ordovician Sandbian (ca 461 to 456 Ma faunas, demonstrates strong endemicity at the species-level. Local endemism is very pronounced, ranging from 25% (e.g. Foxe basin to 75% (e.g. Michigan basin in each basin, a pattern that is also reflected in other benthic faunas such as brachiopods. Multivariate (ordination analyses of the ostracod faunas allow demarcation of a Midcontinent Province and a southern Marginal Province in Laurentia. While these are most clearly differentiated at the stratigraphical level of the bicornis graptolite biozone, analyses of the entire dataset suggest that these provinces remain distinct throughout the Sandbian interval. Differences in species composition between the provinces appear to have been controlled by changes in physical parameters (e.g. temperature and salinity related to water depth and latitude and a possible regional geographic barrier, and these differences persist into the Katian and possibly the Hirnantian. Local environmental parameters, perhaps operating at the microhabitat scale, may have been significant in driving local speciation events from ancestor species in each region. CONCLUSIONS/SIGNIFICANCE: Our work establishes a refined methodology for assessing marine benthic arthropod micro-benthos provinciality for the Early Palaeozoic.

  15. A new age model for the Late Ordovician bentonites in Oslo, Norway

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    Gottschalk Ballo, Eirik; Eivind Augland, Lars; Hammer, Øyvind; Svensen, Henrik

    2017-04-01

    During the Late Ordovician, explosive volcanic eruptions led to the deposition of worldwide bentonites. Some of the largest of these eruptions took place in the Sandbian and produced the Milbrig and Deicke K-bentonites of North America and the Kinnekulle K-bentonite of Scandinavia. We have studied the classic locality of Hagemann and Spjeldnæs (1955) - one of the most complete sections of Ordovician bentonites in Europe. The bentonites are present in the Arnestad Formation comprising dark shale with carbonate nodule beds grading into an increasingly more carbonate rich environment. Through a 50-meter interval we have identified 33 bentonites of which 10 have not previously been reported from this locality. The bentonites have an average thickness of 4.9 cm with a few exceptions such as the Kinnekulle K-bentonite (35 cm) and the Grimstorp B (13 cm). We have measured magnetic susceptibility of two 2-3 meter intervals with a sampling distance of 5 cm, using a handheld magnetic susceptibility meter in the field. These data show significant periodicity peaks that correlate well with Milankovitch cycles and are suggested to represent astronomically forced changes in sediment supply. This study further presents high-precision U-Pb zircon ages of five bentonites from the section, including the Kinnekulle K-bentonite and Grimstorp B. These two beds were previously dated by Svensen et al. (2015) from a locality south of Oslo. Our new data improves the precision of the ages of these two key beds, and constrain the duration of the entire interval and thus the onset and termination of the late Ordovician volcanic system that deposited these tephras. We conclude that the Oslo section provides a high-resolution age model to understand one of the most intense volcanic periods of the Paleozoic by combining radiometric and cyclostratigraphic data. BIBLIOGRAPHY Hagemann, F. and Spjeldnæs, N. (1955). "The Middle Ordovician of the Oslo region, Norway. 6. Notes on bentonites (K

  16. The Late Ordovician crisis: the Large Igneous Province hypothesis tested by global carbon cycle modeling.

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    Lefebvre, Vincent; Servais, Thomas; François, Louis; Averbuch, Olivier

    2010-05-01

    The causes of the well-known Late Ordovician-Hirnantian glaciation remain largely debated. This global cooling event is generally attributed to a severe decrease of atmospheric pCO2 during a time of general greenhouse climate but its duration is not fully determined. The climate perturbation is synchronous with one of the biggest biotic crisis of the Earth history. Some authors have shown that, considering the Ashgillian paleogeography, a drop in pCO2 below a threshold of 8x to 10x PAL (Present Atmospheric Level) may induce a decrease in temperature in high latitudes so that the installation of an ice-sheet on Gondwana could be possible. Such a process requires an intensification of silicate weathering and/or organic carbon burial that are the two major processes potentially driving a decrease in atmospheric pCO2 at the geologic time scale. The Late Ordovician is known to be a period of high mantellic activity marked by a lack of reversal magnetic field and high volcanic activity. Barnes (2004) and Courtillot and Olson (2007) link this process to a superplume event that may give rise to continental basalt flooding. In the present study, we tested this hypothesis with a global carbon cycle numerical box-model coupled with an Energy Balance Climate Model. The Model is an upgrade of that used by Grard et al. (2005) to simulate the environmental impact of the Siberian traps at the P/T boundary. The configuration of the box-model has been set using the Late Ordovician paleogeography. In each oceanic box, the model calculates the evolution of carbon, phosphorus and oxygen concentrations and alkalinity. It also calculates atmospheric pCO2, atmospheric and oceanic δ13C. We tested different scenarios of Large Igneous Province (LIP) emplacements and organic carbon cycle interactions simulating atmospheric pCO2 drops of amplitude large enough to produce the Hirnantian glaciation. We show that the hypothesis of low latitude LIP well accounts for the Late Ordovician climate

  17. The cephalopods of the Boda Limestone, Late Ordovician, of Dalarna, Sweden

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    Björn Kröger

    2013-03-01

    Full Text Available The late Katian, Late Ordovician Boda Limestone of Dalarna, Sweden contains a rich cephalopod assemblage. The assemblage consists of 61 species, of 31 genera, comprising almost all major Ordovician cephalopod orders. Most common and diverse are the Orthocerida. The Ascocerida are also remarkably comman and diverse. The new ascocerid species, Redpathoceras bullatum sp. nov., R. depressum sp. nov., R. magnum sp. nov., and Probillingsites scandinavicum sp. nov., give reason to revise current hypotheses on the origin an evolution of this group. An ascocerid origin from barrandeoceratids or aspidoceratids is hypothesised. The absence of actinocerids in the Boda Limestone is notable, and is interpreted as an indication of relatively cool or/and deep depositional environments. The dominance of orthocerids is provisionally interpreted as evidence for nutrient-rich waters during the time of the deposition of the Boda Limestone. Additionally, the assemblage contains the new barrandeocerids >em>Schuchertoceras fryi sp. nov., Siljanoceras varians gen. et sp. nov., Warburgoceras gen. nov. (for Cyrtoceras longitudinale Angelin in Angelin & Lindström, 1880, the new endocerid Cameroceras turrisoides sp. nov., the new oncocerid Cyrtorizoceras thorslundi sp. nov., and the new orthocerids Dawsonoceras stumburi sp. nov., Isorthoceras angelini sp. nov., I. curvilineatum sp. nov., Nathorstoceras adnatum gen. et sp. nov., N. kallholnense gen. et sp. nov., Palaeodawsonocerina? nicolletoides sp. nov., Pleurorthoceras osmundsbergense sp. nov., and Striatocycloceras isbergi sp. nov.

  18. Sea Level and Paleoenvironment Control on Late Ordovician Source Rocks, Hudson Bay Basin, Canada

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    Zhang, S.; Hefter, J.

    2009-05-01

    Hudson Bay Basin is one of the largest Paleozoic sedimentary basins in North America, with Southampton Island on its north margin. The lower part of the basin succession comprises approximately 180 to 300 m of Upper Ordovician strata including Bad Cache Rapids and Churchill River groups and Red Head Rapids Formation. These units mainly comprise carbonate rocks consisting of alternating fossiliferous limestone, evaporitic and reefal dolostone, and minor shale. Shale units containing extremely high TOC, and interpreted to have potential as petroleum source rocks, were found at three levels in the lower Red Head Rapids Formation on Southampton Island, and were also recognized in exploration wells from the Hudson Bay offshore area. A study of conodonts from 390 conodont-bearing samples from continuous cores and well cuttings from six exploration wells in the Hudson Bay Lowlands and offshore area (Comeault Province No. 1, Kaskattama Province No. 1, Pen Island No. 1, Walrus A-71, Polar Bear C-11 and Narwhal South O-58), and about 250 conodont-bearing samples collected from outcrops on Southampton Island allows recognition of three conodont zones in the Upper Ordovician sequence, namely (in ascendant sequence) Belodina confluens, Amorphognathus ordovicicus, and Rhipidognathus symmetricus zones. The three conodont zones suggest a cycle of sea level changes of rising, reaching the highest level, and then falling during the Late Ordovician. Three intervals of petroleum potential source rock are within the Rhipidognathus symmetricus Zone in Red Head Rapids Formation, and formed in a restricted anoxic and hypersaline condition during a period of sea level falling. This is supported by the following data: 1) The conodont Rhipidognathus symmetricus represents the shallowest Late Ordovician conodont biofacies and very shallow subtidal to intertidal and hypersaline condition. This species has the greatest richness within the three oil shale intervals to compare other parts of Red

  19. Late Ordovician glaciogenic reservoir heterogeneity: An example from the Murzuq Basin, Libya

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    Le Heron, Daniel Paul [CASP, Department of Earth Sciences, University of Cambridge, West Building, 181A Huntingdon Road, CB30DH Cambridge (United Kingdom); Craig, Jonathan [ENI E and P, V. Emilia, 1, San Donato Milanese, MI 20097 (Italy); Sutcliffe, Owen E. [Neftex Petroleum Consultants Ltd., 80A Corinthian Court, Milton Park, Abingdon, Oxfordshire OX14 4RY (United Kingdom); Whittington, Robert [IGES, University of Wales, Aberystwyth, Ceredigion SY23 3DB (United Kingdom)

    2006-07-15

    In North Africa, Late Ordovician glaciogenic reservoirs contain large volume of recoverable hydrocarbon reserves, but their heterogeneity and internal complexity means they are poorly understood. To improve this understanding, this paper presents the case study of the Murzuq Basin, SW Libya, and a synthesis of the stratigraphic architecture of Upper Ordovician glaciogenic reservoirs (the Mamuniyat Formation) within it. Particular attention is paid to regionally extensive stratigraphic boundaries and the geometry of sandstone units of potential reservoir quality. Four disconformity-bound units are recognised, the bounding surfaces of which are flat or of high relief. Unit 1 (the oldest) and Unit 3 are mud-dominated and tend towards non-reservoir. In contrast, Units 2 and 4 (the youngest) are sand-dominated, have poor to excellent reservoir quality but distinctly different sedimentological architectures across the basin. Unit 2 comprises transitions from glaciofluvial/intertidal sandstones to offshore turbidites and formed exclusively during glacial retreat. The occurrence of a significant palaeotopography affected sandbody geometry with glaciofluvial/intertidal deposits concentrating in the lee of these palaeohighs or infilling the bottom of tunnel valleys. Unit 4 is a compound stratigraphic unit recording the effects of glacial retreat and isostatic rebound. In deep marine settings, turbidite fans were deposited during retreat but in shallow water settings, structural reactivation and sediment reworking had a more profound effect on sedimentation. Sedimentological architectures are variable at this level and include prograding coarse clastic wedges (away from a palaeohigh) or the infill of half-graben basins during isostatic rebound. (author)

  20. Late Ordovician brachiopod distribution and ecospace partitioning in the Tvären crater system, Sweden

    DEFF Research Database (Denmark)

    Frisk, Asa M.; Harper, David A. T.

    2013-01-01

    Patterns of distribution and ecospace utilization of Late Ordovician brachiopods in a recently formed, contemporary meteorite crater are described and analyzed. Rhynchonelliformean brachiopod communities, dominated by a wide range of orthides and strophomenides, colonized the newly formed crater....... At the crater rim communities were established early on, although the crater depression was not inhabited until deposition of the upper third of the remaining crater fill. The crater formed a protected but restricted microenvironment where sediments four times the thickness of the nearby basinal succession...... of the guild structure of the fauna permits explanation of a local biodiversity hotspot in otherwise low-diversity strata elsewhere in the Scandinavian region. The Tvaren impact event had an important palaeobiologic effect upon the fossil record as it served as a local pump and reservoir for biodiversity...

  1. Did a gamma-ray burst initiate the late Ordovician mass extinction?

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    Melott, A; Laird, C M; Martin, L; Medvedev, M; Thomas, B; Cannizzo, J K; Gehrels, N; Jackman, C H

    2003-01-01

    At least five times in the history of life, the Earth experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and gamma-ray bursts (GRB) may also have contributed. GRB produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere. Rate estimates suggest that a number of such GRB may lie within the fossil record. The late Ordovician mass extinction shows a water-depth dependent extinction pattern that is a natural result of the attenuation of the strong ultraviolet radiation expected to result from a nearby GRB. In addition, a GRB would trigger global cooling which is associated with this mass extinction.

  2. Allogenic succession in Late Ordovician reefs from southeast China: a response to the Cathaysian orogeny

    Directory of Open Access Journals (Sweden)

    Qijian Li

    2015-02-01

    Full Text Available Several Late Ordovician (late Katian reef complexes are known from the border area of Jiangxi and Zhejiang provinces in southeast China. We studied two coral–stromatoporoid reefs exposed in the Xiazhen Formation at Zhuzhai (Yushan, Jiangxi. The reefs have a combined thickness of 7.4 m and are metazoan-dominated with most reef-builders in growth position. Stromatoporoids and tabulate corals constitute the framework of the reefs. Stromatoporoids (mostly Clathrodictyon dominate the first unit and show a vertical increase in proportion and dominance from the middle part to the top of the unit, whereas tabulate corals (dominated by Catenipora and Agetolites are the main reef-builders in the second unit where stromatoporoids are rare. We attribute this change to a greater tolerance of tabulate corals to turbidity, allowing them to thrive in the muddy facies of the upper unit. This facies change is probably related to the increasing terrestrial input from the northwestward expansion of the Cathaysian Land during the late Katian. The Cathaysian orogeny also led to a short-term exposure of the sea floor in the study area, which terminated the reef growth.

  3. Middle to Late Ordovician faunal studies from central Australia and Tasmania during the Great Ordovician Biodiversification Event

    DEFF Research Database (Denmark)

    Jakobsen, Kristian Grube

    , but the preservation and low number of specimens prevent formal definition of additional new taxa. Although highly endemic at species level, the investigated brachiopod, trilobite and mollusc faunas display a high degree of overall similarity at generic level with Middle Ordovician faunas from North China. Other...... from the Stairway Sandstone, whereas nine brachiopod and five mollusc taxa have been documented from the Cashions Creek Limestone. The new trilobite species Basilicus (Parabasilicus) brumbyensis sp. nov. is described along with the new brachiopod species Amadeuphyla joanae gen. et sp. nov....... and Paralenorthis luritjaorum sp. nov. As well as the new bivalve species Modiolopsis pojetai sp. nov. and Sthenodonta paenesymmetrica sp. nov. All new species derive from the Stairway Sandstone. Several other trilobites, brachiopods and bivalves, described in open nomenclature, probably represent new species...

  4. Depositional Architecture of Late Cambrian-Early Ordovician Siliciclastic Barik Formation; Al Huqf Area, Oman

    Science.gov (United States)

    Abbasi, Iftikhar Ahmed

    2017-04-01

    Early Paleozoic siliciclastics sediments of the Haima Supergroup are subdivided into a number of formations and members based on lithological characteristics of various rock sequences. One of the distinct sandstone sequence, the Barik Formation (Late Cambrian-Early Ordovician) of the Andam Group is a major deep gas reservoir in central Oman. The sandstone bodies are prospective reservoir rocks while thick shale and clay interbeds act as effective seal. Part of the Barik Formation (lower and middle part) is exposed in isolated outcrops in Al Huqf area as interbedded multistoried sandstone, and green and red shale. The sandstone bodies are up to 2 meters thick and can be traced laterally for 300 m to over 1 km. Most of sandstone bodies show both lateral and vertical stacking. Two types of sandstone lithofacies are identified on the basis of field characteristics; a plane-bedded sandstone lithofacies capping thick red and green color shale beds, and a cross-bedded sandstone lithofacies overlying the plane-bedded sandstone defining coarsening upward sequences. The plane-bedded sandstone at places contains Cruziana ichnofacies and bivalve fragments indicating deposition by shoreface processes. Thick cross-bedded sandstone is interpreted to be deposited by the fluvial dominated deltaic processes. Load-casts, climbing ripples and flaser-bedding in siltstone and red shale indicate influence of tidal processes at times during the deposition of the formation. This paper summarizes results of a study carried out in Al Huqf area outcrops to analyze the characteristics of the sandstone-body geometry, internal architecture, provenance and diagenetic changes in the lower and middle part of the formation. The study shows build-up of a delta complex and its progradation over a broad, low-angle shelf where fluvial processes operate beside shoreface processes in a vegetation free setting. Keywords: Andam Group, Barik Formation, Ordovician sandstone, Al Huqf, Central Oman,

  5. Organic geochemical evidence for nitrogen-limited oligotrophic seas in the Late Ordovician

    Science.gov (United States)

    Rohrssen, M.; Love, G. D.

    2011-12-01

    The Late Ordovician (~450-44 Ma) was a period of drastic environmental change, beginning in a hothouse climate with epeiric seaways near a Phanerozoic high and concluding with the Hirnantian glaciation, large positive carbon isotope excursion(s) (Hirnantian isotopic carbon excursion, HICE) and one of the Big Five mass extinctions. Warm sea temperatures and low oxidant concentrations relative to modern likely made intervals of the Late Ordovician particularly suited to the development of extensive denitrification in oxygen minimum zones (OMZs), contributing to nitrogen limitation of marine ecosystems. Mixed carbonate/siliciclastic deposits on Anticosti Island, Canada, provide an excellent opportunity to assemble stratigraphic lipid biomarker records of microbial community structure and response to environmental change associated with the Hirnantian glaciation in a tropical epeiric seaway. Lipid biomarkers extracted from Anticosti rocks yield low thermal maturities, consistent with the shallow burial history of the island and lack molecules likely derived from contamination (e.g. zero oleanane from angiosperms). In addition, Anticosti bitumens bear the C29 sterane predominance and low C28/C29 sterane ratio expected from Lower Paleozoic rocks. Anticosti biomarkers reveal unusual environmenal conditions throughout the Hirnantian at Anticosti. Despite the presence of unequivocally marine fossils, Anticosti bitumens contain no detectable 24-n-propylcholestane, usually a robust marker of marine environmental conditions. Anticosti bitumen have high abundances of 3β-methylhopanes (4-11% of C30 αβ-hopane), molecules which are commonly associated with Type I methanotrophic bacteria. Moderate abundances of 2α-methylhopane (2-4% C30 αβ-hopane) with only trace quantities of gammacerane are found. Hopane/sterane ratios, reflecting a highercontribution of bacteria relative to eukaryotes, range from 1.8 to 11.2 (average 4.8), higher than the Phanerozoic marine average of 0

  6. Ripple marks as indicators of Late Ordovician sedimentary environments in Northwest Estonia

    Directory of Open Access Journals (Sweden)

    Hints, Linda

    2008-03-01

    Full Text Available Late Ordovician sedimentary environments promoting the development of ripple marks in shallow shelf carbonate deposits of northern Estonia are analysed. Ripple marks are described using different parameters (wavelength, height, and wave and asymmetry indexes. Rippled bedding is exposed in a large area in the uppermost Keila Stage, on the upper boundary of micritic-peloidal limestones (Pääsküla Member of the Kahula Formation. Beds with ripples are overlain by organodetrital lime­stones (Saue Member of the Kahula Formation transitional to grainstones or mud mounds of the Vasalemma Formation. The content of peloids in the Pääsküla Member is relatively high and their size (0.04–0.06 mm corresponds to the grain size of sediments capable of forming ripple marks. Weakly asymmetrical sinusoidal ripple marks are oriented in a north–south direction and have likely been formed in the shallow-water zone of the shoal at some distance from the shore. The wave-current origin of the studied ripples can be inferred from ripple indexes. Ripples were subjected to some erosion and in the shallowing-upwards conditions a rocky bottom with the Trypanites ichnofacies evolved. The rippled surface terminates a small-scale cycle (parasequence of the depositional sequence.

  7. Late Ordovician geographic patterns of extinction compared with simulations of astrophysical ionizing radiation damage

    CERN Document Server

    Melott, Adrian L

    2008-01-01

    Based on the intensity and rates of various kinds of intense ionizing radiation events such as supernovae and gamma-ray bursts, it is likely that the Earth has been subjected to one or more events of potential mass extinction level intensity during the Phanerozoic. These induce changes in atmospheric chemistry so that the level of Solar ultraviolet-B radiation reaching surface and near-surface waters may be approximately doubled for up to one decade. This UVB level is known from experiment to be more than enough to kill off many kinds of organisms, particularly phytoplankton. It could easily induce a crash of the photosynthetic-based food chain in the oceans. Certain regularities in the latitudinal distribution of damage are apparent in computational simulations of the atmospheric changes. It was previously proposed that the late Ordovician extinction is a candidate for a contribution from an ionizing radiation event, based on environmental selectivity in trilobites. We confront this hypothesis with data from...

  8. Graptolite community responses to global climate change and the Late Ordovician mass extinction.

    Science.gov (United States)

    Sheets, H David; Mitchell, Charles E; Melchin, Michael J; Loxton, Jason; Štorch, Petr; Carlucci, Kristi L; Hawkins, Andrew D

    2016-07-26

    Mass extinctions disrupt ecological communities. Although climate changes produce stress in ecological communities, few paleobiological studies have systematically addressed the impact of global climate changes on the fine details of community structure with a view to understanding how changes in community structure presage, or even cause, biodiversity decline during mass extinctions. Based on a novel Bayesian approach to biotope assessment, we present a study of changes in species abundance distribution patterns of macroplanktonic graptolite faunas (∼447-444 Ma) leading into the Late Ordovician mass extinction. Communities at two contrasting sites exhibit significant decreases in complexity and evenness as a consequence of the preferential decline in abundance of dysaerobic zone specialist species. The observed changes in community complexity and evenness commenced well before the dramatic population depletions that mark the tipping point of the extinction event. Initially, community changes tracked changes in the oceanic water masses, but these relations broke down during the onset of mass extinction. Environmental isotope and biomarker data suggest that sea surface temperature and nutrient cycling in the paleotropical oceans changed sharply during the latest Katian time, with consequent changes in the extent of the oxygen minimum zone and phytoplankton community composition. Although many impacted species persisted in ephemeral populations, increased extinction risk selectively depleted the diversity of paleotropical graptolite species during the latest Katian and early Hirnantian. The effects of long-term climate change on habitats can thus degrade populations in ways that cascade through communities, with effects that culminate in mass extinction.

  9. A Lipid Biomarker Stratigraphic Record through the Late Ordovician Mass Extinction

    Science.gov (United States)

    Rohrssen, M.; Love, G. D.; Fike, D. A.; Finnegan, S.; Fischer, W. W.; Jones, D. S.

    2010-12-01

    The Late Ordovician (~450-440 Ma) was a period of major environmental change, as indicated by evidence for short-duration (history of strata on the island, lack signs of petroleum-derived contamination (e.g. zero oleanane signal from angiosperms and other self-checks), and yield the C29 sterane predominance and low C28/C29 sterane ratios typical of the Early Paleozoic. These sediments, which bear marine fossils, lack the marine marker 24-n-propylcholestane, and have high 3β-methylhopane (4-11% of C30 αβ-hopane) and moderate 2α-methylhopane (2-4% C30 αβ-hopane) indices, most commonly associated with methanotrophs and cyanobacteria, respectively. Gammacerane is present only in trace amounts. Hopane/sterane ratios range from 1.8 to 11.2 (average = 4.7), with most values significantly above the Phanerozoic marine average values of 0.5-2.0, indicating a high contribution of bacterial input to sedimentary organic matter. Lower hopane/sterane values (average = 2.2) are generally found coincident with the carbon isotope excursion. Taken together, the lipid biomarker data suggest a stressed oligotrophic marine ecosystem in which N2-fixing bacterial communities dominate over eukaryotic algae, possibly as a response to nitrate-limitation in the low-sulfate Paleozoic ocean.

  10. The Species-Area Relationship in the Late Ordovician: A Test Using Neutral Theory

    Directory of Open Access Journals (Sweden)

    Steven M. Holland

    2013-04-01

    Full Text Available The fundamental biodiversity number, θ, as proposed by Hubbell, should be positively correlated with province area. Because θ can be calculated from preserved relative abundance distributions, this correlation can be tested in the fossil record for regions with known provinces. Late Ordovician (443–458 Ma strata of Laurentia are divided into four geochemically and biologically distinct regions that reflect provinces in the epicontinental sea. We use existing and newly obtained bed-level census data to test whether Hubbell’s θ is positively correlated with the area of these four regions, corresponding roughly to the Appalachian Basin, Cincinnati Arch, Upper Mississippi Valley, and western United States and Canada. Results indicate a positive relationship between province area and θ that suggests the influence of provincial area, among other factors, on diversity. This correlation highlights the inherent link between diversity and abundance structure at local and regional scales, such that changes at one scale will necessarily affect the other. Since diversity at these smaller spatial scales is an important component of global biodiversity, determining the nature of this relationship in the fossil record has implications for understanding how diversity is assembled globally throughout the Phanerozoic.

  11. Graptolite community responses to global climate change and the Late Ordovician mass extinction

    Science.gov (United States)

    Sheets, H. David; Mitchell, Charles E.; Melchin, Michael J.; Loxton, Jason; Štorch, Petr; Carlucci, Kristi L.; Hawkins, Andrew D.

    2016-07-01

    Mass extinctions disrupt ecological communities. Although climate changes produce stress in ecological communities, few paleobiological studies have systematically addressed the impact of global climate changes on the fine details of community structure with a view to understanding how changes in community structure presage, or even cause, biodiversity decline during mass extinctions. Based on a novel Bayesian approach to biotope assessment, we present a study of changes in species abundance distribution patterns of macroplanktonic graptolite faunas (˜447-444 Ma) leading into the Late Ordovician mass extinction. Communities at two contrasting sites exhibit significant decreases in complexity and evenness as a consequence of the preferential decline in abundance of dysaerobic zone specialist species. The observed changes in community complexity and evenness commenced well before the dramatic population depletions that mark the tipping point of the extinction event. Initially, community changes tracked changes in the oceanic water masses, but these relations broke down during the onset of mass extinction. Environmental isotope and biomarker data suggest that sea surface temperature and nutrient cycling in the paleotropical oceans changed sharply during the latest Katian time, with consequent changes in the extent of the oxygen minimum zone and phytoplankton community composition. Although many impacted species persisted in ephemeral populations, increased extinction risk selectively depleted the diversity of paleotropical graptolite species during the latest Katian and early Hirnantian. The effects of long-term climate change on habitats can thus degrade populations in ways that cascade through communities, with effects that culminate in mass extinction.

  12. Organic geochemistry of Mid-Continent middle and Late Ordovician oils

    Energy Technology Data Exchange (ETDEWEB)

    Longman, M.W.; Palmer, S.E.

    1987-08-01

    Ordovician oils in Mohawkian and Cincinnatian reservoirs of the US Mid-Continent retain the biochemical imprint of Middle and Upper Ordovician oceanic life before the evolution of land plants and most vertebrates. Thus, these oils have some geochemical features that distinguish them from younger oils. These features include (1) a predominance of n-C/sub 15/, n-C/sub 17/, and n-C/sub 19/ alkanes in the saturated hydrocarbon fraction, (2) relatively low amounts of longer chain n-alkanes, (3) low amounts of chlorophyll-derived isoprenoids, such as pristane and phytane, and (4) abundant C/sub 29/ sterane relative to C/sub 27/ with rearranged forms (diasteranes) predominant over normal steranes. Ordovician oils also generally contain little sulfur and have a somewhat variable light stable carbon isotopic composition with delta/sup 13/C/sub sat/ and delta/sup 13/C/sub aro/ values of -28 to -31 per thousand (PDB), but these features are typical of many marine oils. The unusual chemistry of these Ordovician oils supports the interpretation of Reed, Illich, and Horsfield (1986) that prokaryotic organisms provided the organic matter for most Ordovician oils. Although their claim for Gloeocapsamorpha (a problematic unicellular prokaryote, possibly a blue-green alga or an unusually large bacterium) cannot be proven from oil chemistry alone, knowing that indigenous Mid-Continent Ordovician oils were derived from prokaryotic organisms may aid in future exploration for these reservoirs. 7 figures, 3 tables.

  13. The Uniform Rugosity Effect

    Science.gov (United States)

    Bonnivard, Matthieu; Bucur, Dorin

    2012-06-01

    Relying on the effect of microscopic asperities, one can mathematically justify that viscous fluids adhere completely on the boundary of an impermeable domain. The rugosity effect accounts asymptotically for the transformation of complete slip boundary conditions on a rough surface in total adherence boundary conditions, as the amplitude of the rugosities vanishes. The decreasing rate (average velocity divided by the amplitude of the rugosities) computed on close flat layers is definitely influenced by the geometry. Recent results prove that this ratio has a uniform upper bound for certain geometries, like periodical and "almost Lipschitz" boundaries. The purpose of this paper is to prove that such a result holds for arbitrary (non-periodical) crystalline boundaries and general (non-smooth) periodical boundaries.

  14. High potential for chemical weathering and climate effects of early lichens and bryophytes in the Late Ordovician

    Science.gov (United States)

    Porada, Philipp; Lenton, Tim; Pohl, Alexandre; Weber, Bettina; Mander, Luke; Donnadieu, Yannick; Beer, Christian; Pöschl, Ulrich; Kleidon, Axel

    2016-04-01

    Non-vascular vegetation in the Late Ordovician may have considerably increased global chemical weathering, thereby reducing atmospheric CO2 concentration and contributing to a decrease in global temperature and the onset of glaciations. Usually, enhancement of weathering by non-vascular vegetation is estimated using field experiments which are limited to small areas and a low number of species. This makes it difficult to extrapolate to the global scale and to climatic conditions of the past, which differ markedly from the recent climate. Here we present a global, spatially explicit modelling approach to estimate chemical weathering by non-vascular vegetation in the Late Ordovician. During this period, vegetation probably consisted of early forms of today's lichens and bryophytes. We simulate these organisms with a process-based model, which takes into account their physiological diversity by representing multiple species. The productivity of lichens and bryophytes is then related to chemical weathering of surface rocks. The rationale is that the organisms dissolve rocks to extract phosphorus for the production of new biomass. To account for the limited supply of unweathered rock material in shallow regions, we cap biotic weathering at the erosion rate. We estimate a potential global weathering flux of 10.2 km3 yr-1 of rock, which is around 12 times larger than today's global chemical weathering. The high weathering potential implies a considerable impact of lichens and bryophytes on atmospheric CO2 concentration in the Ordovician. Moreover, we find that biotic weathering is highly sensitive to atmospheric CO2, which suggests a strong feedback between chemical weathering by lichens and bryophytes and climate.

  15. Late Ordovician (post-Sardic) rifting branches in the North Gondwanan Montagne Noire and Mouthoumet massifs of southern France

    DEFF Research Database (Denmark)

    Javier Álvaro, J.; Colmenar Lallena, Jorge; Monceret, Eric

    2016-01-01

    Upper Ordovician-Lower Devonian rocks of the Cabrières klippes (southern Montagne Noire) and the Mouthoumet massif in southern France rest paraconformably or with angular discordance on Cambrian-Lower Ordovician strata. Neither Middle-Ordovician volcanism nor associated metamorphism is recorded...

  16. The Peerless structure, Daniels County, northeastern Montana: A probable late Ordovician impact structure

    Science.gov (United States)

    Comstock, J. M.; Dietz, R. D.; Morrow, J. R.

    2004-05-01

    The Peerless structure is an ~6 km-diameter sub-surface anomaly located in Daniels County, northeastern Montana. The disruption of sedimentary rock in the structure lies between 2624 to 2818 m below the topographic surface. Seismic mapping shows a typical complex crater composed of a central uplift ~2 km across, which shows structural uplift of up to 90 m, an annular ring ~4 km across, and an outer rim ~6 km in diameter. The youngest disrupted rock unit is the upper Ordovician Red River formation, which indicates that the structure was formed about 430-450 Ma ago.

  17. Early Paleozoic (Late Cambrian-Early Ordovician) acritarchs from the metasedimentary Baden-Baden-Gaggenau zone (Schwarzwald, SW Germany).

    Science.gov (United States)

    Montenari, M; Servais, T

    2000-12-01

    The metasediments of the low-grade metamorphosed Baden-Baden-Gaggenau zone of the northern Schwarzwald (southwestern Germany) have been analyzed palynologically. From 133 samples representing different metasedimentary units, only three samples of the upper part of the Traischbach Serie provide extremely poorly-preserved palynomorphs. The assemblage consists of the galeate acritarch genera Caldariola, Cymatiogaleaand Stelliferidium, as well as specimens of diacromorph and polygonomorph acritarchs. Although determinations are difficult at the generic level and essentially impossible at the specific level, the assemblage can be attributed to an interval between the Late Cambrian and Early Ordovician. This is the first biostratigraphical age assignment for the metasediments of the Baden-Baden-Gaggenau zone, which can possibly be correlated with the Villé Unit of the northern Vosges Mountains (eastern France).

  18. Tropical shoreline ice in the late Cambrian: Implications for earth's climate between the Cambrian Explosion and the Great Ordovician Biodiversification Event

    Science.gov (United States)

    Runkel, Anthony C.; MacKey, T.J.; Cowan, Clinton A.; Fox, David L.

    2010-01-01

    Middle to late Cambrian time (ca. 513 to 488 Ma) is characterized by an unstable plateau in biodiversity, when depauperate shelf faunas suffered repeated extinctions. This poorly understood interval separates the Cambrian Explosion from the Great Ordovician Biodiversification Event and is generally regarded as a time of sustained greenhouse conditions. We present evidence that suggests a drastically different climate during this enigmatic interval: Features indicative of meteoric ice are well preserved in late Cambrian equatorial beach deposits that correspond to one of the shelf extinction events. Thus, the middle to late Cambrian Earth was at least episodically cold and might best be considered a muted analogue to the environmental extremes that characterized the Proterozoic, even though cooling in the two periods may have occurred in response to different triggers. Such later Cambrian conditions may have significantly impacted evolution preceding the Ordovician radiation.

  19. Deposition in anoxic Taconic foreland basin, late Middle Ordovician, New York

    Energy Technology Data Exchange (ETDEWEB)

    Hay, B.J.; Cisne, J.L.

    1984-12-01

    The Taconic foreland basin resulted from a collision between the North American craton and the Ammonoosuc arc. The basin is positioned between a broad carbonate shelf on the west and the clastic arc terrane. In the downslope direction, basin deposits changed from distal shelf carbonates (Trenton Limestone), to coeval interbedded hemipelagic black shales and calcilutites on the slope (Dolgeville Formation and Utica Shale), to silty shales, siltstones, and sandstones laid down by turbidites on the basin floor (Snake Hill Shale). From the distribution of organic carbon and the concentration of benthic epifauna and infauna, it can be inferred that conditions were aerobic on the shelf (>1 ml/L O/sub 2/), anaerobic on the slope (<0.4 ml/L O/sub 2/), and dysaerobic on the basin floor (<1 ml/L O/sub 2/). Through time, four long-term anaerobic and dysaerobic cycles are revealed, lasting between 500,000 and 1,000,000 yr. Anaerobic cycles are characterized by over 50% higher organic carbon values, lack of infaunal burrowing traces, and a highly impoverished benthic epifauna. Dysaerobic cycles are marked by lower organic carbon contents, sporadic burrowing traces, and a slightly more diverse and abundant benthic epifauna. The longest anaerobic cycle occurred during the transgressive phase that led to widespread deposition of black shale over the carbonate platform. Anoxic conditions in the Taconic foreland basin may have been influenced by the prevailing global oceanographic conditions during the Middle Ordovician.

  20. The effects of the final stages of the Late Ordovician glaciation on marine palynomorphs (chitinozoans, acritarchs, leiospheres) in well Nl-2 (NE Algerian Sahara).

    Science.gov (United States)

    Paris, F; Bourahrouh, A; Hérissé, A L.

    2000-12-01

    Palynomorph assemblages, especially chitinozoans and acritarchs, from the Upper Ordovician of well Nl-2 (north-east of the Algerian Sahara) are studied in order to precisely date the ultimate effects of the Late Ordovician glaciation and to document the impact of this major climatic stress on the diversity of the palynoplankton. References are made to stable isotope excursions and to global eustatic sea level variations in order to improve the local age determination. The Hassi el Hadjar Formation, i.e. glacio-marine diamictites, is interpreted as a transgressive event resulting from the melting of the northern Gondwana ice cap. It yields poorly preserved and moderately diverse chitinozoans of late Hirnantian age. Acritarchs are more abundant in the lower part of these "microconglomeratic clays", but display a low diversity and are badly preserved throughout the whole formation. Reworked individuals are recorded in both groups. The marine sediments of the M'Kratta Formation of latest Hirnantian age contain better preserved, more abundant and more diverse palynomorph assemblages, especially in the Upper Member. The composition of this palynoplankton indicates a fairly good faunal and phytoplankton recovery after the early Hirnantian climatic stress.The extinction of the Ordovician forms, and the appearance of Silurian type taxa occur only in the uppermost Hirnantian, i.e. following with a slight delay the glacial event. The overlying black shales of Wenlock age (lower part of the Oued Mehaiguène Formation) are indicative of marine anoxic environments. They yield a virtually exclusive, but enormous number of Tasmanacea. The very peculiar composition of this palynoplankton seems to be independent of the Late Ordovician glaciation and is most likely related to the factors that, later, generated and maintained anoxic conditions in this area.A new species of chitinozoan, Spinachitina oulebsiri sp. nov. from the latest Hirnantian M'Kratta Formation, is described and

  1. Review and palaeoecological analysis of the late Tremadocian – early Floian (Early Ordovician cephalopod fauna of the Montagne Noire, France

    Directory of Open Access Journals (Sweden)

    B. Kröger

    2011-02-01

    Full Text Available The Early Ordovician successions of the southern Montagne Noire consist of a thick sequence of predominantly siliciclastic sediments of which the late Tremadocian St. Chinian Formation and the earliest Floian La Maurerie Formation contain a comparatively rich and abundant cephalopod association. The cephalopods of the St. Chinian and La Maurerie Formation are interpreted as generally authochthonous, representing a fauna which originally lived in the open water above the sediments or related to the sea bottom. The cephalopod associations of the St. Chinian and La Maurerie formations are similar to other contemporaneous assemblages known from higher palaeolatitudes and associated with deeper depositional settings. They are composed almost exclusively of longiconic orthocones, in this case predominantly of eothinoceratids and baltocerids. The occurrences of Annbactrocera, and Bactroceras in the St. Chinian Formation are at present the earliest unambiguous reports of the Orthocerida. The available data suggest an initial expansion of orthoceroid cephalopod faunas from open water habitats of high paleo-latitudes, and a subsequent expansion on the carbonate platforms during the Floian. The presence of the eothinoceratid Saloceras in abundance demonstrates the Gondwanan affinity of the assemblage whilst adding further support for the presence of a "Saloceras realm" that may have extended along the margins of East and West Gondwana at least into intermediate latitudes. The following new taxa are proposed: Annbactroceras n. gen., Annbactroceras felinense n. sp., Cyclostomiceras thorali n. sp., Felinoceras n. gen., Felinoceras constrictum n. sp., Lobendoceras undulatum n. sp., Rioceratidae n. fam., Saloceras murvielense n. sp., Thoraloceras n. gen., Thoraloceras bactroceroides n. sp. doi:10.1002/mmng.201000013

  2. Late Ordovician (post-Sardic) rifting branches in the North Gondwanan Montagne Noire and Mouthoumet massifs of southern France

    Science.gov (United States)

    Javier Álvaro, J.; Colmenar, Jorge; Monceret, Eric; Pouclet, André; Vizcaïno, Daniel

    2016-06-01

    Upper Ordovician-Lower Devonian rocks of the Cabrières klippes (southern Montagne Noire) and the Mouthoumet massif in southern France rest paraconformably or with angular discordance on Cambrian-Lower Ordovician strata. Neither Middle-Ordovician volcanism nor associated metamorphism is recorded, and the subsequent Middle-Ordovician stratigraphic gap is related to the Sardic phase. Upper Ordovician sedimentation started in the rifting branches of Cabrières and Mouthoumet with deposition of basaltic lava flows and lahar deposits (Roque de Bandies and Villerouge formations) of continental tholeiite signature (CT), indicative of continental fracturing. The infill of both rifting branches followed with the onset of (1) Katian (Ka1-Ka2) conglomerates and sandstones (Glauzy and Gascagne formations), which have yielded a new brachiopod assemblage representative of the Svobodaina havliceki Community; (2) Katian (Ka2-Ka4) limestones, marlstones, and shales with carbonate nodules, reflecting development of bryozoan-echinoderm meadows with elements of the Nicolella Community (Gabian and Montjoi formations); and (3) the Hirnantian Marmairane Formation in the Mouthoumet massif that has yielded a rich and diverse fossil association representative of the pandemic Hirnantia Fauna. The sealing of the subaerial palaeorelief generated during the Sardic phase is related to Silurian and Early Devonian transgressions leading to onlapping patterns and the record of high-angle discordances.

  3. Lipid Biomarkers of the Maquoketa Formation, Iowa: Transect of a Paleobathymetry Gradient in the Lead-Up to the Late Ordovician Mass Extinction

    Science.gov (United States)

    Rohrssen, M.; Love, G. D.

    2012-12-01

    The Late Ordovician (~450-44 Ma) was a period of drastic environmental change, beginning in a hothouse climate with epeiric seaways near a Phanerozoic high and concluding with the Hirnantian glaciation, large positive carbon isotope excursion(s) (Hirnantian isotopic carbon excursion, HICE) and one of the Big Five mass extinctions. The two-phased expression of the Late Ordovician mass extinction has been attributed to regression-driven habitat loss and the consequences of cooling climate, followed by transgression of oxygen-deficient bottom water onto previously oxygenated shelves. Lipid biomarker records indicate substantial changes in microbial communities during the glacial maximum and mass extinction (Rohrssen et al., in press); to fully uncouple the effects of sea level-driven facies change from more regional or global factors we have analyzed lipid biomarkers along a shallow to deep water paleobathymetry gradient in central Laurentia across a transgressive-regressive cycle. We compare results from the Maquoketa Formation to previous work on Hirnantian- and Katian-age rocks to develop a better understanding of the association of microbial communities with Late Ordovician-age epeiric sea and upwelling environments. During deposition of the Katian-age Maquoketa Formation, Iowa was bounded to the north by exposed highlands of the Transcontinental Arch and separated from the southeastern half of the Laurentian epeiric seaway by a northeast-southwest trending shelf-break into the deeper waters of the Seebree Trough, a depression thought to have connected central and eastern Laurentia to the open ocean. As a result of this paleotopography, samples of the Maquoketa Formation collected from drill cores BS5 (Clayton County), SS-15 (Jackson County), and H33 (Des Moines County) in a transect from northeastern to southeastern Iowa capture the change in facies from carbonate-rich platform to shale with phosphatic intervals at the shelf-break in contemporaneous deposits

  4. Geochronology and Geochemistry of Middle-Late Ordovician Granites and Gabbros in the Erguna Region, NE China:Implications for the Tectonic Evolution of the Erguna Massif

    Institute of Scientific and Technical Information of China (English)

    Shuo Zhao; Wenliang Xu; Wei Wang; Jie Tang; Yihan Zhang

    2014-01-01

    Zircon U-Pb ages, Hf isotope data and whole-rock major and trace element data for the Middle to Late Ordovician gabbros and granites in the Erguna Massif, NE China were presented in this paper. The petrogenesis of these rocks and the Early Paleozoic tectonic evolution of the massif were discussed. Zircons from the granites and gabbros are of magmatic origin based on their cathodolumi-nescence (CL) images. The206Pb/238U ages obtained from 20 spots on zircons from the granites range from 446±9 to 464±10 Ma, yielding a weighted mean age of 455±10 Ma; and 16 spots on zircons from the gabbros range from 465±10 to 466±7 Ma, yielding a weighted mean age of 465±2 Ma. Chemically, the Late Ordovician granites in the Erguna Massif are weakly peraluminous and similar to A-type granites. The granites and gabbros are all enriched in light rare earth elements and large ion lithophile elements (e.g., Rb, K), and depleted in heavy rare earth elements and high field strength elements (e.g., Nb, Ta, and Ti); they all exhibit marked negative Eu anomalies. Their zirconεHf(t) values range mainly from +1.86 to +6.21 (for the granites) and +1.39 to +3.89 (for the gabbros), except for one spot with a value of -0.27 (for a gabbro). TheTDM1 ages for the gabbros andTDM2 ages for the granites vary from 928 to 1 091 Ma and from 1 287 to 1 675 Ma, respectively. It is concluded that the primary magma of the granites could have been derived by partial melting of Mesoproterozoic newly accreted crustal ma-terial, whereas the primary magma of the gabbros originated by partial melting of a depleted mantle wedge that had been metasomatized by fluids derived from a subducted slab. These Middle-Late Or-dovician granites and gabbros constitute a typical bimodal igneous rock association, implying an exten-sional environment that was probably related to the post-collisional development of the Erguna and Xing’an massifs in the early Early Paleozoic.

  5. Chitinozoan zonation of the Late Ordovician and the Early Silurian of the island of Anticosti, Québec, Canada.

    Science.gov (United States)

    Soufiane; Achab

    2000-04-01

    A reappraisal of chitinozoan distribution across the Ordovician-Silurian boundary on the Island of Anticosti has led to the recognition of a new zone, the Ancyrochitina ellisbayensis biozone, in the uppermost part of the Ellis Bay Formation. This biozone lies between the well defined Upper Ordovician Spinachitina taugourdeaui biozone and the lowest Silurian (Rhuddanian) Plectochitina nodifera biozone of the Becscie Formation. The occurrence of such diagnostic species as P. nodifera, Belonechitina postrobusta, Conochitina electa and Ancyrochitina ramosaspina in the Lower Silurian of Anticosti points to a close similarity to faunas in Estonia and north Latvia and indicates an age ranging from the Parakidograptus acuminatus to the Coronograptus cyphus in terms of graptolite zones. The chitinozoan biozonation harmonizes with that based on conodonts and, to a lesser extent, with the known graptolite faunal succession. Five new species: Ancyrochitina ellisbayensis sp. nov., Clathrochitina postconcinna sp. nov., Conochitina gunriveris sp. nov., Clathrochitina perexilis sp. nov., Bursachitina basiconcava sp. nov. and three species in open nomenclature are described.

  6. Early Silurian(Telychian)rugose coral fauna of Daguan area, northeast Yunnan Province,China

    Institute of Scientific and Technical Information of China (English)

    CHEN Jianqiang; HE Xinyi; TANG Lan

    2006-01-01

    Study on rugose coral fauna of the Sifengya Formation(early Telyehian)and Daluzhai Formation (mid-late Telychian)in Daguan area,northeast Yunnan Province,China was carded out.Rugose coral fauna of the Sifengya Formation included 18 genera and 34 species,while Daluzhai Formation with nine genera,ten species.We described rugose coral fauna(12 genera,19 species)including one new genus and five new species,i.e.Protoketophyllum daguanense gen.et sp.nov..Crassilasma huanggexiense sp.nov.,Pseudophaulactis heae sp.nov.,P.convolutus sp.nov.,and Shensiphyllum minor sp.nov..The characteristics and geological significance of rugose coral fauna of Sifengya Formation and Daluzhai Formation were analyzed.Particularly,mgose coral fauna of the Sifengya Formation represent early Telychian rugosan fauna in the Upper Yangtze region and improve the sequences of early Silurian(Llandovery)mgose coral assemblages in Yangtze region.It is therefore very meaningful to further analyze radiation period of rugose coral fauna in such epoch.

  7. Integrating bio-, chemo- and sequence stratigraphy of the Late Ordovician, Early Katian: A connection between onshore and offshore facies using carbon isotope analysis: Kentucky, Ohio, USA

    Science.gov (United States)

    Young, Allison; Brett, Carlton; McLaughlin, Patrick

    2017-04-01

    A common problem in stratigraphic correlation is the difficulty of bridging shallow water shelf carbonates and down ramp shale-rich facies. This issue is well exemplified by the Upper Ordovician (lower Katian) Lexington Limestone of Kentucky, USA and adjacent dark shale facies in the deeper water Sebree Trough, an elongate, narrow bathymetric low abruptly north of the outcrop belt in the Ohio subsurface. Chronostratigraphic schemes for this interval have been proposed on the basis of conodont and graptolite biostratigraphy, mapping of event beds, and sequence stratigraphy through facies analysis. The relation of the siliciclastic rich offshore records of the "Point Pleasant-Utica" interval, well known to drillers because of its oil and gas potential, with the up-ramp shallow water carbonate dominated equivalents of the Lexington Formation is complicated by convoluted nomenclature, a major, abrupt change in facies, and disparity in the availability and completeness of records. Current genetic models of organic rich shale intervals, such as the Point Pleasant-Utica interval, are still lacking in detail, and will greatly benefit from detailed correlation with shallow water settings where more is understood about paleoclimatic conditions. In order to understand the development and evolution of this Late Ordovician Laurentian basin, it is important to understand the age relationships of depositional processes occurring at a range of depths, particularly in the less well studied epeiric sea setting of the "Point Pleasant-Utica" interval of Ohio and partial lateral equivalent, Lexington Formation of central Kentucky. The outcrop area of central Kentucky, exposed by the later uplift of the Cincinnati Arch, hosts numerous world-class exposures of the Lexington Formation, nearly all of which are representative of the highly fossiliferous, shallow-water marine platform carbonates. These successions display well differentiated depositional sequences, with sharp facies offsets

  8. Ordovician paleomagnetism of eastern Yunnan, China

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Wu; Van der Voo, R. (Univ. of Michigan, Ann Arbor (USA)); Liang, Qizhong (Yunnan Institute of Geological Sciences, Kunming (China))

    1990-06-01

    Three magnetic components have been isolated in Ordovician formations of the Yangtze Paraplatform (South China Block). Two of these (Daqing A and Hongshiya B components) yield paleopoles that conform to the Carboniferous to Triassic segment of the apparent polar wander path for South China, and are therefore interpreted as remagnetizations. The third component (declination/inclination = 301{degree}/+66{degree}, N = 5 sites, k = 21.4, {alpha}{sub 95} = 17{degree}) passes the fold test and is interpreted as primary (late Early Ordovician). The paleopole, at 39{degree}S, 236{degree}E, and the paleolatitude of 48{degree}S support an Ordovician position of South China adjacent to Gondwana.

  9. 内蒙古西部额济纳旗晚奥陶世生物地理和奥陶-志留系分界%LATE ORDOVICIAN BIOGEOGRAPHY AND ORDOVICIAN-SILURIAN BOUNDARY IN THE ZHUSILENHAIERHAN AREA, EJIN, WESTERN INNER MONGOLIA

    Institute of Scientific and Technical Information of China (English)

    戎嘉余; 陈旭; 詹仁斌; 周志强; 郑昭昌; 王怿

    2003-01-01

    Upper Ordovician-lowest Silurian strata crop out near Danmianshan, about 10 km west of Zhusilenghaierhan Mt., about 55 km south of Yagan, 135 km east of Ejin Banner town, western Inner Mongolia (Alxa block). The strata along with their related major fossil groups (such as graptolites, corals and trilobites) have been studied by Zheng et al. (1982), Zhu et al. (1987), and Ge et al. (1990). Recent field examination in this area was carried out by the authors in the summer of 2002. Our subsequent investigation on collections has led to the discovery Holorhynchus (virgianids, Brachiopoda) from the Late Ordovician rocks, to make sure that there occur no latest Ordovician Hirnantia fauna, and to define the Ordovician-Silurian boundary on the basis of the occurrence of Normalograptus lubricus. The Ashgill brachiopod biogeography is discussed.Holorhynchus giganteus Kiaer, 1902 has been found from the Badanjilin Fomation (mid Ashgill) at the No. 3 section of Zheng et al. (1987) in this area for the first time. This is also the first record of the genus Holorhynchus in Late Ordovician of China. Holorhynchus has been known to be characterized by the total absence of a ventral median septum, together with smooth shell exterior and short, separated outer brachial plates (e.g. St. Joseph, 1938; Cocks, 1982). Through sectioning, however, the discovery of an apical median setum in ventral valve of immature specimens (less than 8mm wide) of H. giganteus led to a revised generic diagnosis for the genus (see Rong et al. in preparation). Actually, this structure is also known from an internal mold material and a transverse section of the identical species in South Norway (Cocks, 1982) and Zeravshano-Gissar Mountains, Tadzhikistan (Nikiforova and Sapel'nikov, 1973) respectively. Holorhynchus from the Badanjilin Formation at the No.3 section of Zheng et al. (1987) is associated with the brachiopods Altaethyrella, Ovalospira, Leptellina, Sowerbyella, Pectenospira, and the Agetolites

  10. Ordovician and Late Paleozoic Early Mesozoic tectonothermal history of the La Noria area, northern Acatlán Complex, southern Mexico: Record of convergence in the Rheic and paleo-Pacific Oceans

    Science.gov (United States)

    Hinojosa-Prieto, H. R.; Nance, R. D.; Keppie, J. D.; Dostal, J. V.; Ortega-Rivera, A.; Lee, J. K. W.

    2008-12-01

    The La Noria area lies in the northern part of the polydeformed Acatlán Complex, (southern Mexican Mixteca terrane), and the rocks record the following sequence of events: (i) Early-Middle Ordovician deposition of the volcaniclastic El Epazote and Las Calaveras units; (ii) late Middle Ordovician intrusion of the 467 ± 16 Ma megacrystic, peraluminous, rift-related granitoids; (iii) late Devonian, D 1, greenschist facies deformation; (iv) intrusion of the Los Malpasos leucogranite and associated minor intrusions; (v) Middle Mississippian, D 2, dextral N-S deformation also under greenschist facies metamorphic conditions; and (vi) undated D 3 kink band development. U-Pb LA-ICPMS detrital zircon ages: (a) the El Epazote unit yielded: a mean 206Pb/ 238U age from the youngest five concordant 206Pb/ 238Pb age of 488 ± 10 Ma, with other age peaks at ca. 506, ca. 1077, and ca. 1779 Ma and a few concordant Neoproterozoic ages: and (b) the Las Calaveras unit yielded a mean 206Pb/ 238U age from the sixteen youngest detrital zircons of 466 ± 10 Ma with other population age peaks ca. 1111, and ca. 1753 Ma. These data imply that granitoid intrusion was roughly synchronous with deposition of some of the host rocks. Whereas sources for most of the detrital zircons may be found in either the Acatlán and Oaxacan complexes, Laurentia or Gondwana, a Neoproterozoic source is most likely in Amazonia. The rocks record three low-grade deformational episodes: (i) D 1 produced a weak compositional banding and/or schistosity (S 1) under greenschist facies conditions; (ii) D 2, also occurred under greenschist facies conditions, and developed tight to isoclinal folds (F 2) in S 1 and an axial planar spaced-cleavage (S 2) that is co-planar with S 1; and (iii) D 3 produced reverse and conjugate kink bands (F 3) that deform the S 1/S 2 composite foliation. The leucogranite and related dikes that intrude the complex record only the latter two deformational events. Ca. 330 Ma 40Ar/ 39Ar

  11. Rugosity grid derived from gridded bathymetry of Apra Harbor, Guam U.S. Territory

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (1 m cell size) multibeam bathymetry, collected aboard the Survey Vessel Swamp Fox using the Terrain Modeler with rugosity methods...

  12. Rugosity Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity was calculated from the bathymetry surface for each cell using the "Rugosity" function in the Benthic Terrain Modeler toolbox (Jenness 2002, 2004; Wright et...

  13. Ordovician faunas of Burgess Shale type.

    Science.gov (United States)

    Van Roy, Peter; Orr, Patrick J; Botting, Joseph P; Muir, Lucy A; Vinther, Jakob; Lefebvre, Bertrand; el Hariri, Khadija; Briggs, Derek E G

    2010-05-13

    The renowned soft-bodied faunas of the Cambrian period, which include the Burgess Shale, disappear from the fossil record in the late Middle Cambrian, after which the Palaeozoic fauna dominates. The disappearance of faunas of Burgess Shale type curtails the stratigraphic record of a number of iconic Cambrian taxa. One possible explanation for this loss is a major extinction, but more probably it reflects the absence of preservation of similar soft-bodied faunas in later periods. Here we report the discovery of numerous diverse soft-bodied assemblages in the Lower and Upper Fezouata Formations (Lower Ordovician) of Morocco, which include a range of remarkable stem-group morphologies normally considered characteristic of the Cambrian. It is clear that biotas of Burgess Shale type persisted after the Cambrian and are preserved where suitable facies occur. The Fezouata biota provides a link between the Burgess Shale communities and the early stages of the Great Ordovician Biodiversification Event.

  14. High-resolution conodont oxygen isotope record of Ordovician climate change

    Science.gov (United States)

    Chen, J.; Chen, Z.; Algeo, T. J.

    2013-12-01

    The Ordovician Period was characterized by several major events, including a prolonged 'super greenhouse' during the Early Ordovician, the 'Great Ordovician Biodiversification Event (GOBE)' of the Middle and early Late Ordovician, and the Hirnantian ice age and mass extinction of the latest Ordovician (Webby et al., 2004, The Great Ordovician Biodiversification Event, Columbia University Press). The cause of the rapid diversification of marine invertebrates during the GOBE is not clear, however, and several scenarios have been proposed including widespread development of shallow cratonic seas, strong magmatic and tectonic activity, and climate moderation. In order to investigate relationships between climate change and marine ecosystem evolution during the Ordovician, we measured the oxygen isotopic composition of single coniform conodonts using a Cameca secondary ion mass spectrometer. Our δ18O profile shows a shift at the Early/Middle Ordovician transition that is indicative of a rapid 6 to 8 °C cooling. This cooling event marks the termination of the Early Ordovician 'super greenhouse' and may have established cooler tropical seawater temperatures that were more favorable for invertebrate animals, setting the stage for the GOBE. Additional cooling episodes occurred during the early Sandbian, early Katian, and Hirnantian, the last culminating in a short-lived (extinction. Our results differ from those of Trotter et al. (2008, 'Did cooling oceans trigger Ordovician biodiversification? Evidence from conodont thermometry,' Science 321:550-554). Instead of a slow, protracted cooling through the Early and Middle Ordovician, our high-resolution record shows that cooling occurred in several discrete steps, with the largest step being at the Early/Middle Ordovician transition.

  15. Precisely locating the Ordovician equator in Laurentia

    DEFF Research Database (Denmark)

    Jin, Jisuo; Harper, David A.T.; Cocks, L. Robin M.

    2013-01-01

    The Late Ordovician equatorial zone, like the zone today, had few hurricane-grade storms within 100 of the equator, as emphasized by the preservation of massive-bedded Thalassinoides ichnofacies in a trans-Laurentian belt more than 6000 km long, from the southwestern United States to North...... Greenland. That belt also includes nonamalgamated shell beds dominated by the brachiopod Proconchidium, which would not have been preserved after hurricane-grade storms. The belt lacks such storm-related sedimentary features as rip-up clasts, hummocky cross-stratification, or large channels. In contrast...

  16. SHRIMP U-Pb dating of recurrent Cryogenian and Late Cambrian-Early Ordovician alkalic magmatism in central Idaho: Implications for Rodinian rift tectonics

    Science.gov (United States)

    Lund, K.; Aleinikoff, J.N.; Evans, K.V.; duBray, E.A.; deWitt, E.H.; Unruh, D.M.

    2010-01-01

    margin subsidence, (3) late Ediacaran-Cambrain rifting, and (4) welldeveloped late Ediacaran-Devonian passive margin subsidence and deposition. Timing and geometries support synchronous but opposing divergence along Cordilleran and Atlantic rifts with a junction in Southern California-Sonora. ?? 2010 Geological Society of America.

  17. DEVONIAN RUGOSE CORALS FROM THE KARAKORUM MOUNTAINS (NORTHERN PAKISTAN

    Directory of Open Access Journals (Sweden)

    STEFAN SCHRÖDER

    2004-11-01

    Full Text Available The Karakorum Block is regarded as a microplate of "Gondwanan" origin and was part of the Cimmerian continent ("Mega Lhasa" which rifted away from the northern margin of Gondwana during the Late Palaeozoic/Early Mesozoic. From the Northern Karakorum Range (Yarkhun and Karambar River Valleys: structurally belonging to the Northern Sedimentary Belt an Upper Givetian to Lower Frasnian rugose coral fauna of the Shogram Formation is described. The fauna is dominated by cosmopolitan genera such as Hexagonaria, Disphyllum, Macgeea and the Temnophyllum/Spinophyllum group, generally showing a geographically wide distribution, although being absent from the Eastern Americas Realm in the Upper Givetian/Lower Frasnian. Therefore its components are of little use for biogeographical deductions at sub-realm level, and in explaining the relation between the Karakorum Range and other Cimmerian crustal blocks. A remarkable exception is the first record of the genus Pseudopexiphyllum outside of Turkey, indicating a connection to the western part of the Cimmerides. On species level, the coral fauna of the Shogram Formation is characterized by the development of a diverse and rather unique fauna including about 35 taxa, that differs from the faunas known from neighbouring crustal blocks. So far, faunistic links to the Central Iranian Microcontinent (Yazd-, and Tabas-Block, the northwest Iranian Plate (Elburz, Central Pamir, the Lhasa Block and Western Qiangtang are not clear, and although each of these fragments are believed to be closely connected they were apparently not in direct contact during the Devonian. However, the Karakorum fauna is remarkably close to one known from the Helmand Block in Afghanistan, showing a very similar generic composition that includes numerous morphologically closely related, although not identical species. Accordingly, the restricted faunal exchange led to the development of new taxa. Distribution of the new species of Spinophyllum

  18. High-frequency rugose exopolysaccharide production by Vibrio cholerae strains isolated in Haiti.

    Directory of Open Access Journals (Sweden)

    Mustafizur Rahman

    Full Text Available In October, 2010, epidemic cholera was reported for the first time in Haiti in over 100 years. Establishment of cholera endemicity in Haiti will be dependent in large part on the continued presence of toxigenic V. cholerae O1 in aquatic reservoirs. The rugose phenotype of V. cholerae, characterized by exopolysaccharide production that confers resistance to environmental stress, is a potential contributor to environmental persistence. Using a microbiologic medium promoting high-frequency conversion of smooth to rugose (S-R phenotype, 80 (46.5% of 172 V. cholerae strains isolated from clinical and environmental sources in Haiti were able to convert to a rugose phenotype. Toxigenic V. cholerae O1 strains isolated at the beginning of the epidemic (2010 were significantly less likely to shift to a rugose phenotype than clinical strains isolated in 2012/2013, or environmental strains. Frequency of rugose conversion was influenced by incubation temperature and time. Appearance of the biofilm produced by a Haitian clinical rugose strain (altered biotype El Tor HC16R differed from that of a typical El Tor rugose strain (N16961R by confocal microscopy. On whole-genome SNP analysis, there was no phylogenetic clustering of strains showing an ability to shift to a rugose phenotype. Our data confirm the ability of Haitian clinical (and environmental strains to shift to a protective rugose phenotype, and suggest that factors such as temperature influence the frequency of transition to this phenotype.

  19. The adaptive significance of sexually dimorphic scale rugosity in sea snakes.

    Science.gov (United States)

    Avolio, Carla; Shine, Richard; Pile, Adele J

    2006-05-01

    In terrestrial snakes, rugose scales are uncommon and (if they occur) generally are found on both sexes. In contrast, rugose scales are seen in most sea snakes, especially in males. Why has marine life favored this sex-specific elaboration of scale rugosity? We pose and test alternative hypotheses about the function of rugose scales in males of the turtle-headed sea snake (Emydocephalus annulatus) and conclude that multiple selective forces have been involved. First, rugosities may aid male positioning during courtship, because histology shows that tubercles are more highly innervated than adjacent flat areas of each scale and hence are presumably more sensitive to tactile cues, and because biomechanical tests show that rugosities enhance friction between the bodies of males and females. Second, the occurrence of rugosities over the entire body of males and (albeit less well developed) in females as well suggests that rugosities also play a hydrodynamic role by modifying water flow across the snake's surface. Flow tank tests show that rugosities reduce the thickness of the boundary layer by almost 50% and create turbulent flow that should massively enhance rates of cutaneous oxygen uptake and hence prolong maximal courtship duration by males.

  20. High-frequency rugose exopolysaccharide production by Vibrio cholerae strains isolated in Haiti.

    Science.gov (United States)

    Rahman, Mustafizur; Jubair, Mohammad; Alam, Meer T; Weppelmann, Thomas A; Azarian, Taj; Salemi, Marco; Sakharuk, Ilya A; Rashid, Mohammed H; Johnson, Judith A; Yasmin, Mahmuda; Morris, J Glenn; Ali, Afsar

    2014-01-01

    In October, 2010, epidemic cholera was reported for the first time in Haiti in over 100 years. Establishment of cholera endemicity in Haiti will be dependent in large part on the continued presence of toxigenic V. cholerae O1 in aquatic reservoirs. The rugose phenotype of V. cholerae, characterized by exopolysaccharide production that confers resistance to environmental stress, is a potential contributor to environmental persistence. Using a microbiologic medium promoting high-frequency conversion of smooth to rugose (S-R) phenotype, 80 (46.5%) of 172 V. cholerae strains isolated from clinical and environmental sources in Haiti were able to convert to a rugose phenotype. Toxigenic V. cholerae O1 strains isolated at the beginning of the epidemic (2010) were significantly less likely to shift to a rugose phenotype than clinical strains isolated in 2012/2013, or environmental strains. Frequency of rugose conversion was influenced by incubation temperature and time. Appearance of the biofilm produced by a Haitian clinical rugose strain (altered biotype El Tor HC16R) differed from that of a typical El Tor rugose strain (N16961R) by confocal microscopy. On whole-genome SNP analysis, there was no phylogenetic clustering of strains showing an ability to shift to a rugose phenotype. Our data confirm the ability of Haitian clinical (and environmental) strains to shift to a protective rugose phenotype, and suggest that factors such as temperature influence the frequency of transition to this phenotype.

  1. Ordovician Graptolite Rhabdosome Complication and Its Implications on Sea Level Changes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A total of four times of rhabdosome complication events, i.e., the lateral branching of graptolite stipes during the Late Middle Ordovician, the secondary branching of graptolite stipes at the earliest Upper Ordovician, the early Qiantangjiangian of Upper Ordovician and the middle Qiantangjiangian, respectively, is discussed in this paper. These events and other adaptation events demonstrate close relationships between a diverse graptolite fauna and sea level changes, and consequently can be employed to study sea level fluctuations. It is safe to conclude that the complication of rhabdosome started at the maximum flooding surface (MFS) and terminated at the beginning of regression.

  2. A giant Ordovician anomalocaridid.

    Science.gov (United States)

    Van Roy, Peter; Briggs, Derek E G

    2011-05-26

    Anomalocaridids, giant lightly sclerotized invertebrate predators, occur in a number of exceptionally preserved early and middle Cambrian (542-501 million years ago) biotas and have come to symbolize the unfamiliar morphologies displayed by stem organisms in faunas of the Burgess Shale type. They are characterized by a pair of anterior, segmented appendages, a circlet of plates around the mouth, and an elongate segmented trunk lacking true tergites with a pair of flexible lateral lobes per segment. Disarticulated body parts, such as the anterior appendages and oral circlet, had been assigned to a range of taxonomic groups--but the discovery of complete specimens from the middle Cambrian Burgess Shale showed that these disparate elements all belong to a single kind of animal. Phylogenetic analyses support a position of anomalocaridids in the arthropod stem, as a sister group to the euarthropods. The anomalocaridids were the largest animals in Cambrian communities. The youngest unequivocal examples occur in the middle Cambrian Marjum Formation of Utah but an arthropod retaining some anomalocaridid characteristics is present in the Devonian of Germany. Here we report the post-Cambrian occurrence of anomalocaridids, from the Early Ordovician (488-472 million years ago) Fezouata Biota in southeastern Morocco, including specimens larger than any in Cambrian biotas. These giant animals were an important element of some marine communities for about 30 million years longer than previously realized. The Moroccan specimens confirm the presence of a dorsal array of flexible blades attached to a transverse rachis on the trunk segments; these blades probably functioned as gills.

  3. Digital reef rugosity estimates coral reef habitat complexity.

    Science.gov (United States)

    Dustan, Phillip; Doherty, Orla; Pardede, Shinta

    2013-01-01

    Ecological habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity.

  4. Diversity history of Ordovician graptolites and its relationship with environmental change

    Institute of Scientific and Technical Information of China (English)

    ZHANG YuanDong; CHEN Xu

    2008-01-01

    innovation of graptolites: planktonic forms were derived from their benthic ancestors. This derivation resulted in the great guild expansion of graptolites. In late Early Ordovician (Floian), the global expansion of graptolites commenced. From the Floian to the end of Middle Ordovician, the graptolites diversity increased remarkably and displayed three peaks for all the regions. However, the peaks are somewhat distinct in magnitude and timing among regions. The Darriwilian peak is prominent in both South China and Baltic region, but inconspicuous in Australasia. No close relationship between the graptolite diversification and the palaeolatitudes are supported herein. Instead, the graptolite diversification seems to coincide with the global sea-level rises, suggesting a possible intrinsic relationship between them.

  5. Diversity history of Ordovician graptolites and its relationship with environmental change

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    ecological innovation of graptolites: planktonic forms were derived from their benthic ancestors. This derivation resulted in the great guild expansion of graptolites. In late Early Ordovician (Floian), the global expansion of graptolites commenced. From the Floian to the end of Middle Ordovician, the graptolites diversity increased remarkably and displayed three peaks for all the regions. However, the peaks are somewhat distinct in magnitude and timing among regions. The Darriwilian peak is prominent in both South China and Baltic region, but inconspicuous in Australasia. No close relationship between the graptolite diversification and the palaeolatitudes are supported herein. Instead, the graptolite diversification seems to coincide with the global sea-level rises, suggesting a possible intrinsic relationship between them.

  6. Relationships between reef fish communities and remotely sensed rugosity measurements in Biscayne National Park, Florida, USA

    Science.gov (United States)

    Kuffner, Ilsa B.; Brock, John C.; Grober-Dunsmore, Rikki; Bonito, Victor E.; Hickey, T. Donald; Wright, C. Wayne

    2007-01-01

    The realization that coral reef ecosystem management must occur across multiple spatial scales and habitat types has led scientists and resource managers to seek variables that are easily measured over large areas and correlate well with reef resources. Here we investigate the utility of new technology in airborne laser surveying (NASA Experimental Advanced Airborne Research Lidar (EAARL)) in assessing topographical complexity (rugosity) to predict reef fish community structure on shallow (n = 10–13 per reef). Rugosity at each station was assessed in situ by divers using the traditional chain-transect method (10-m scale), and remotely using the EAARL submarine topography data at multiple spatial scales (2, 5, and 10 m). The rugosity and biological datasets were analyzed together to elucidate the predictive power of EAARL rugosity in describing the variance in reef fish community variables and to assess the correlation between chain-transect and EAARL rugosity. EAARL rugosity was not well correlated with chain-transect rugosity, or with species richness of fishes (although statistically significant, the amount of variance explained by the model was very low). Variance in reef fish community attributes was better explained in reef-by-reef variability than by physical variables. However, once the reef-by-reef variability was taken into account in a two-way analysis of variance, the importance of rugosity could be seen on individual reefs. Fish species richness and abundance were statistically higher at high rugosity stations compared to medium and low rugosity stations, as predicted by prior ecological research. The EAARL shows promise as an important mapping tool for reef resource managers as they strive to inventory and protect coral reef resources.

  7. 中上扬子晚奥陶世赫南特期岩相古地理%Lithofacies palaeogeography of the Late Ordovician Hirnantian in the middle-upper Yangtze region of China

    Institute of Scientific and Technical Information of China (English)

    刘伟; 许效松; 余谦; 闫剑飞; 门玉澎; 张海全

    2012-01-01

    The beginning of Hirnantian in Late Ordovician was followed by a global episode of Gondwana glaciation. Typical deposits were Guanyinqiao Formation deposits in the middle-upper Yangtze region of China during the period of the global sea-level fall caused by the ice-sheet growth. There, the worldwide spread Hirnantia-Dalmanitina fauna was abundant. According to lithologic characters, sedimentary structures, and biological assemblages and their preserved states, Hirnantian can be mainly classified as tidal flat facies and neritic shelf facies. There are several subfacies and microfacies in this study area. In the tidal flat facies, the Guanyinqiao Formation is mainly composed of carbon-argillaceous limestone and calcareous mudstone, including benthos of brachiopodas and trilobites of Hirnantia-Dalmanitina fauna. In the neritic shelf facies, however, the Hirnantian stage is composed of black siliceous shale and radiolarian chert in Normalograptus extraordinarius zone in the upper part of the Wufeng Formation and the Guanyinqiao Formation is absent. The results show that the Hirnantian, in succession of the paleogeographic framework in the late Katian stage, also has the characteristics of the semi-restricted shallow sea. Regionally, it succeeds the environment of the neritic shelf facies in the late Katian stage in the north of the upper Yangtze and the most part of the middle Yangtze region, as well as the tidal flat facies among the middle Sichuan uplift, middle Guizhou uplift and Kangdian old land. In the neritic shelf facies, the Guanyinqiao Formation shelly facies limestone deposited only in the Huangling anticline-Shenlongjia in the middle Hubei, Chengkou in Chongqing and Songxi in the southeast of Hubei as sea level was falling. In the tidal flat facies, the intraclast beach deposits distributed mainly over the north margin of the middle Guizhou uplift, but those deposits were absent in some lower areas. Within the process of sea-level falling to the lowest, in

  8. Early Silurian (Aeronian East Point Coral Patch Reefs of Anticosti Island, Eastern Canada: First Reef Recovery from the Ordovician/Silurian Mass Extinction in Eastern Laurentia

    Directory of Open Access Journals (Sweden)

    Jisuo Jin

    2012-05-01

    Full Text Available An extensive late Aeronian patch reef swarm outcrops for 60–70 km on Anticosti Island, eastern Canada, located in the inner to mid-shelf area of a prominent tropical carbonate platform of southeastern Laurentia, at 20°–25° S paleolatitude of the southern typhoon belt. This complex, described here for the first time, includes more than 100 patch reefs, up to 60–80 m in diameter and 10 m high. Reefs are exposed three-dimensionally on present-day tidal flats, as well as inland along roads and rivers. Down the gentle 1°–2° paleoslope, the reefs grade into coral-sponge biostromes, and westerly they grade into inter-reef or deeper ‘crinoidal meadow’ facies. The reef builders were dominantly tabulate and rugose corals, with lesser stromatoporoids. Other components include crinoids, brachiopods, green algae (especially paleoporellids, and encrusting cyanobacteria: reefs display some of the earliest known symbiotic intergrowths of corals and stromatoporoids. Reefs were variably built on a base of crinoidal grainstones, meadows of baffling tabulate corals, brachiopod shells, or chlorophytes. These reefs mark an early phase of reef recovery after a prominent reef gap of 5–6 million years following the Ordovician/Silurian mass extinction events. The reefs feature a maximal diversity of calcifying cyanobacteria, corals and stromatoporoids, but low diversity of brachiopods, nautiloids and crinoids. Following the North American Stratigraphic Code, we define herein the Menier Formation, encompassing the lower two members of the existing Jupiter Formation.

  9. Hydrocarbon charging histories of the Ordovician reservoir in the Tahe oil field, Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    李纯泉; 陈红汉; 李思田; 张希明; 陈汉林

    2004-01-01

    The Ordovician reservoir of the Tahe oil field went through many tectonic reconstructions, and was characterized by multiple hydrocarbon chargings. The aim of this study was to unravel the complex charging histories. Systematic analysis of fluid inclusions was employed to complete the investigation. Fluorescence observation of oil inclusions under UV light, and microthermometry of both oil and aqueous inclusions in 105 core samples taken from the Ordovician reservoir indicated that the Ordovician reservoir underwent four oil chargings and a gas charging. The hydrocarbon chargings occurred at the late Hercynian, the Indo-Sinian and Yanshan, the early Himalaya, the middle Himalaya, and the late Himalaya,respectively. The critical hydrocarbon charging time was at the late Hercynian.

  10. Hydrocarbon charging histories of the Ordovician reservoir in the Tahe oil field, Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    李纯泉; 陈红汉; 李思田; 张希明; 陈汉林

    2004-01-01

    The Ordovician reservoir of the Tahe oil field went through many tectonic reconstructions, and was charac-terized by multiple hydrocarbon chargings. The aim of this study was to unravel the complex charging histories. Systematicanalysis of fluid inclusions was employed to complete the investigation. Fluorescence observation of oil inclusions underUV light, and microthermometry of both oil and aqueous inclusions in 105 core samples taken from the Ordovician reservoirindicated that the Ordovician reservoir underwent four oil chargings and a gas charging. The hydrocarbon chargings oc-curred at the late Hercynian, the Indo-Sinian and Yanshan, the early Himalaya, the middle Himalaya, and the late Himalaya,respectively. The critical hydrocarbon charging time was at the late Hercynian.

  11. Rugosity grid (5 m) derived from gridded bathymetry of Saipan Island, Commonwealth of the Northern Marianas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) bathymetry from two sources: Multibeam bathymetry collected by Coral Reef Ecosystem Division aboard NOAA R/V AHI,...

  12. 60 m Rugosity grid derived from gridded bathymetry of Wake Island, West Central Pacific.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (60 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

  13. Rugosity 5m grid derived from gridded bathymetry of Brooks Banks, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

  14. Rugosity grid derived from gridded bathymetry of French Frigate Shoals, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

  15. Rugosity grid (5 m) derived from gridded bathymetry of the US Territory of Guam

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) bathymetry from four sources: Multibeam bathymetry collected by Coral Reef Ecosystem Division aboard NOAA R/V AHI,...

  16. 10 m Rugosity grid derived from gridded bathymetry of Wake Island, West Central Pacific.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

  17. Rugosity grid derived from gridded bathymetry of Rose Atoll, Territory of American Samoa, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard R/V AHI, and bathymetry derived from multispectral IKONOS satellite imagery....

  18. Rugosity grid derived from gridded bathymetry of Swains Island, Territory of American Samoa, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (40 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. Cell values reflect the (surface area) /...

  19. Rugosity 20m grid derived from gridded bathymetry of Brooks Banks, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (20 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

  20. Rugosity grid derived from gridded bathymetry of of Baker Island, Pacific Remote Island Areas, Central Pacific.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (20 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. Cell values reflect the (surface area) /...

  1. Rugosity grid derived from gridded bathymetry of Kure Atoll, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, and IKONOS derived depths using the Benthic...

  2. CRED Rugosity grid derived from gridded bathymetry of Tutuila Island, American Samoa, South Pacific

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

  3. Rugosity grid derived from gridded bathymetry of Ni'ihau Island, Hawaii, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

  4. Rugosity grid derived from gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (40 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. Cell values reflect the (surface area) /...

  5. Obsidianus lapis rugosity and hardness determination: fibre laser craftsmanship

    Science.gov (United States)

    Aguilar-Morales, A. I.; Velazquez-Gonzalez, J. S.; Marrujo-García, S.; Reyes-Sanchez, J. I.; Alvarez-Chávez, J. A.

    2014-05-01

    Obsidianus lapis is a volcanic rock that has been worked into tools for cutting or weaponry by Teotihuacan people for hundreds of years. Currently it is used in jewelry or for house decorative items such as elaborated sculptures. From the physico-chemical properties point of view, obsidianus lapis is considered a glass as its composition is 80% silicon dioxide. In México there are different kinds of obsidianus lapis according to its colour: rainbow, black, brown, red, silver, golden and snowflake. The traditional grinding process for working with obsidianus lapis includes fixed grinders and sandpaper for the polishing process, where the craftsman grinds the rock manually obtaining a variety of shapes. Laser processing of natural stones is a relatively new topic. We propose the use of an Yb3+-doped fibre laser for cutting and ablating obsidianus lapis into spherical, rectangular and oval shapes. By means of a theoretical analysis of roughness and hardness, which affect the different surfaces and final shapes, and considering the changes in material temperature during laser interaction, this work will focus on parameter determination such as: laser fluence, incidence angle, laser average power and peak pulse energy, from the proposed Q-switched fibre laser design. Full optical, hardness and rugosity, initial and final, characterization will be included in the presentation.

  6. Ordovician rafinesquinine brachiopods from peri-Gondwana

    Directory of Open Access Journals (Sweden)

    Jorge Colmenar

    2016-06-01

    Full Text Available The study of the strophomenide brachiopods of the subfamily Rafinesquininae present in the main Upper Ordovician sections, representing the Mediterranean margin of Gondwana, has revealed an increase in diversity of the group at the region during that time. The studied collections are from the Moroccan Anti-Atlas, the Iberian and the Armorican massifs, the Iberian Chains, Pyrenees, Montagne Noire, Sardinia, and Bohemia. Two genera of the subfamily Rafinesquininae have been recorded. Of them, the cosmopolitan Rafinesquina is the only one previously reported from the region and Kjaerina is found for the first time outside Avalonia, Baltica, and Laurentia. Additionally, two new subgenera have been described, Kjaerina (Villasina and Rafinesquina (Mesogeina. Furthermore, the new species Rafinesquina (Mesogeina gabianensis, Rafinesquina (Mesogeina loredensis, Kjaerina (Kjaerina gondwanensis, Kjaerina (Villasina pedronaensis, Kjaerina (Villasina pyrenaica, and Kjaerina (Villasina meloui have been described. In addition, other species of these genera previously known from isolated localities in the region, such as Rafinesquina pseudoloricata, Rafinesquina pomoides, and Hedstroemina almadenensis are revised and their geographic range expanded. The adaptive radiation experienced by the rafinesquinines at the Mediterranean region during middle to late Katian, was probably related to changes in the regime of sedimentation and water temperature caused by the global warming Boda event.

  7. Ordovician chitinozoan diversification events in China

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaofeng; CHEN; Xiaohong

    2004-01-01

    Correlative study of the Ordovician chitinozoan biostratigraphy in China with graptolite and conodont biozones, and comprehensive analysis of the sequence- and event-stratigraphic indicated that 17 chitinozoan zones and 5 main chitinozoan diversification events subsequently occurring could be recognized in the Ordovician System of China. The 5 events comprise: event 1-appearance of the earliest Ordovician chitinozoans, event 2-appearance of C. symmetrica, event 3-juvenile radiation of chitinozoans, event 4-appearance of chitinozoans with high diversity, and event 5-development of chitinozoans of deep-water facies. The age and feature of each event and its relation with the sea-level change and other geological event are discussed.

  8. Nacre in Molluscs from the Ordovician of the Midwestern United States

    Directory of Open Access Journals (Sweden)

    Steven D.J. Baumann

    2013-01-01

    Full Text Available Nacre was previously thought to be primitive in the Mollusca, but no convincing Cambrian examples are known. This aragonitic microstructure with crystal tablets that grow within an organic framework is thought to be the strongest, most fracture-resistant type of shell microstructure. Fossils described herein from the Ordovician of Iowa, Indiana, and Ohio provide supporting evidence for the hypothesis that sometime between the middle Cambrian and late Ordovician, nacre originated in cephalopod, bivalve, and possibly gastropod lineages. The correlation of independent origins of fracture-resistant nacre with increasing shell-crushing abilities of predators during the Cambrian-Ordovician suggests an early pulse in the evolutionary arms race between predators and molluscan prey.

  9. Hydrocarbon Accumulation Conditions of Ordovician Carbonate in Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    LI Qiming; WU Guanghui; PANG Xiongqi; PAN Wenqin; LUO Chunshu; WANG Chenglin; LI Xinsheng; ZHOU Bo

    2010-01-01

    Based on comprehensive analysis of reservoir-forming conditions,the diversity of reservoir and the difference of multistage hydrocarbon charge are the key factors for the carbonate hydrocarbon accumulation of the Ordovician in the Tarim Basin.Undergone four major deposition-tectonic cycles,the Ordovician carbonate formed a stable structural framework with huge uplifts,in which are developed reservoirs of the reef-bank type and unconformity type,and resulted in multistage hydrocarbon charge and accumulation during the Caledonian,Late Hercynian and Late Himalayan.With low matrix porosity and permeability of the Ordovician carbonate,the secondary solution pores and caverns serve as the main reservoir space.The polyphase tectonic movements formed unconformity reservoirs widely distributed around the paleo-uplifts; and the reef-bank reservoir is controlled by two kinds of sedimentary facies belts,namely the steep slope and gentle slope.The unconventional carbonate pool is characterized by extensive distribution,no obvious edge water or bottom water,complicated oil/gas/water relations and severe heterogeneity controlled by reservoirs.The low porosity and low permeability reservoir together with multi-period hydrocarbon accumulation resulted in the difference and complex of the distribution and production of oil/gas/water.The distribution of hydrocarbon is controlled by the temporal-spatial relation between revolution of source rocks and paleo-uplifts.The heterogenetic carbonate reservoir and late-stage gas charge are the main factors making the oil/gas phase complicated.The slope areas of the paleo-uplifts formed in the Paleozoic are the main carbonate exploration directions based on comprehensive evaluation.The Ordovician of the northern slope of the Tazhong uplift,Lunnan and its periphery areas are practical exploration fields.The Yengimahalla-Hanikatam and Markit slopes are the important replacement targets for carbonate exploration.Gucheng,Tadong,the deep layers of

  10. Bioerosion of Inorganic Hard Substrates in the Ordovician of Estonia (Baltica.

    Directory of Open Access Journals (Sweden)

    Olev Vinn

    Full Text Available The earliest bioeroded inorganic hard substrates in the Ordovician of Estonia appear in the Dapingian. Hardgrounds are also known from the Sandbian and Katian. Most of the bioerosion of inorganic hard substrates occurs as the boring Trypanites Mägdefrau, 1932 along with some possible Gastrochaenolites borings. North American hardground borings are more diverse than those in Baltica. In contrast to a worldwide trend of increasing boring intensity, the Estonian record seems to show no increase in boring intensities during the Middle and Late Ordovician. Hardgrounds seem to be more common during the temperate climate interval of the Ordovician calcite sea in Estonia (seven hardgrounds during 15 my than in the part with a tropical climate (four hardgrounds during 12 my. Bioerosion is mostly associated with carbonate hardgrounds, but cobbles and pebbles broken from the hardgrounds are also often penetrated by Trypanites borings. The general diversity of boring ichnotaxa in Baltica increased from one ichnospecies in the Cambrian to seven by the end of Ordovician, showing the effect of the GOBE on bioeroding ichnotaxa. The diversity of inorganic hard substrate borers increased by only two times. This difference can be explained by the wider environmental distribution of organic as compared to inorganic substrates in the Ordovician seas of Baltica, and their more continuous temporal availability, which may have caused increased specialization of several borers. The inorganic substrates may have been bioreroded only by the generalists among boring organisms.

  11. Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

    Institute of Scientific and Technical Information of China (English)

    QING Hai-ruo

    2004-01-01

    The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.

  12. Principal aspects of the Ordovician biotic radiation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Ordovician radiation is among the major bioevents in earth history that have drawn great attention from geologists all over the world, and there have been hundreds of publications treating various aspects of this radiation. The study of the event involves a broad spectrum of research fields and concerns many scientific questions. Many opinions and hypotheses have been proposed on the triggering and controlling factors of the radiation. Herein the authors critically review the study of the Ordovician radiation and dissect four principal aspects by synthesizing the studies over the past years: (1) relationships of the radiation to fossil clades, ecotypes, and environments, such as water depth, latitude, and climate; (2) the ecological structure and food webs of Ordovician marine organisms; (3) fossil records and true biodiversities; and (4) likely triggering and controlling factors of the Ordovician radiation. The authors also recommend approaches to furthering studies of these aspects.

  13. Rock-dwelling lizards exhibit less sensitivity of sprint speed to increases in substrate rugosity.

    Science.gov (United States)

    Collins, Clint E; Self, Jessica D; Anderson, Roger A; McBrayer, Lance D

    2013-06-01

    Effectively moving across variable substrates is important to all terrestrial animals. The effects of substrates on lizard performance have ecological ramifications including the partitioning of habitat according to sprinting ability on different surfaces. This phenomenon is known as sprint sensitivity, or the decrease in sprint speed due to change in substrate. However, sprint sensitivity has been characterized only in arboreal Anolis lizards. Our study measured sensitivity to substrate rugosity among six lizard species that occupy rocky, sandy, and/or arboreal habitats. Lizards that use rocky habitats are less sensitive to changes in substrate rugosity, followed by arboreal lizards, and then by lizards that use sandy habitats. We infer from comparative phylogenetic analysis that forelimb, chest, and tail dimensions are important external morphological features related to sensitivity to changes in substrate rugosity.

  14. Seawater fluid inclusions preserved within Cambrian-Ordovician marine cements indicate Cambrian-Ordovician seawater precipitated low-magnesium calcite

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.J.; Goldstein, R.H. (Univ. of Kansas, Lawrence, KS (United States). Dept. of Geology)

    1992-01-01

    The San Saba Member of the Wilberns Formation (Llano Uplift, Texas) contains a series of Late Cambrian-Early Ordovician hardgrounds. Bladed low-Mg calcite cements are truncated at hardground surfaces and overlain by shallow marine limestones, indicating a syndepositional shallow marine origin. Primary one-phase fluid inclusions within bladed cements have marine salinities, suggesting that these low-Mg calcite cements formed as a precipitate from Late Cambrian and Early Ordovician seawater and have not undergone recrystallization. Stable isotope analysis of the bladed cement yields delta O-18 values that cluster between [minus]5.6--[minus]6.0 ([per thousand] PDB) which is comparable to those previously reported for Early Ordovician marine calcite. The delta C-13 values are more positive than those reported for this time interval (0.6--1.3 [per thousand] PDB). Trace element analysis indicates that strontium content ranges from 200 to 2,200 ppm. Iron ranges from below detection by electron microprobe to 800 ppm. Mg is generally below detection, however, cements in one hardground display Mg contents that increase progressively toward pore centers. Trace element data lack covariance that would suggest recrystallization. In addition, closed system recrystallization cannot be supported here due to a lack of microdolomite inclusions. Stable isotope, trace element, and fluid inclusion data are consistent with submarine cementation at or below the sediment-water interface. These cements have not undergone significant recrystallization and preserve a primary low Mg calcite mineralogy. These data suggest that early Paleozoic seawater differed chemically from modern seawater. Moreover, preservation of ancient seawater, within fluid inclusions, may provide a direct means of determining those differences.

  15. Autografted vines of cultivar ‘Refošk’ (Vitis vinifera L. reveal symptoms of the rugose wood disease

    Directory of Open Access Journals (Sweden)

    Matjaž HLADNIK

    2015-12-01

    Full Text Available Rugose wood disease complex is one of the most important graft-transmissible grapevine diseases and it is considered to be a viral disease. With the aim to obtain more information about appearance of rugose wood disease observed on cultivar ‘Refošk’, ‘Refošk’ vines from collection vineyard in Komen were used for green grafting on SO4 rootstock and autografts for control were made as well. Rugose wood symptoms were observed on grafts of two ‘Refošk’ biotypes, which confirmed graft transmissibility. Appearance of rugose wood symptoms on autografts excluded the impact of incompatibility in rugose wood disease, but at the same time it could be proposed that stress caused by grafting has an important role.

  16. Ordovician Intrusive-related Gold-Copper Mineralization in West-Central New South Wales, Australia

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Three major types of Ordovician intrusive-related gold-copper deposits are recognized in central-west New South Wales,, Australia: porphyry, skam and high sulphidation epithermal deposits.These deposits are mainly distributed within two Ordovician volcano-intrusive belts of the Lachlan Fold Be1t: the Orange-Wellington Belt and the Parkes-Narromine Belt. Available isotopic age data suggest that mineralization of the three types of deposits is essentially coeval with the Ordovician intrusive rocks (480-430 Ma). Porphyry gold-copper deposits can be further divided into two groups. The first group is associated with monzoniteshowing shoshonitic features represented by Cadia and Goonumbla. The second group is associated with diorite and dacite, including the Copper Hill and Cargo gold-copper deposits. Gold skarn is associated with Late Ordovician (430-439 Ma) monzonitic intrusive complexes in the Junction Reefs area (Sheahan-Grants, Frenchmans, and Cornishmens), Endeavour 6, 7 and 44, Big and Little Cadia. The epithermal gold deposits with high sulphidation including Gidginbung (Temora) and Peak Hill mainly occur within Ordovician andesite and volcaniclastic rocks, and are associated with advanced argillic alteration. Available isotopic age data indicate that both alteration and mineralization of the porphyry, skam and epithermal gold-copper deposits are broadly coeval with the Late Ordovician hoshonitic mangmatism, which is thought to result from the melting of sub-continental lithosphere caused by Palaeozoic subduction events. The Ordovician intrusive-related gold-copper deposits are restricted to two longitudinal parallel volcano-intrusive belts, rarely extending outside them. Diagonal intra-belt trends of mineralization are common, particularly at the intersections of longitudinal and transverse (oblique) fault/fracture zones basedon the authors'review of available geological data. The locations of these gold-copper deposits are obviously influenced by transverse

  17. Upper Ordovician and Lower Silurian chitinozoans from central Nevada and Arctic Canada.

    Science.gov (United States)

    Soufiane, A; Achab, A

    2000-12-01

    Late Ordovician and Early Silurian chitinozoans from the uppermost Vinini Formation, and the Hanson Creek Formation in central Nevada and the lower Cape Phillips Formation, Cape Manning section, in Arctic Canada have been re-investigated and a new chitinozoan biozonation is proposed. The Upper Ordovician of central Nevada can easily be correlated to that of Arctic Canada through the common occurrence of the Ordochitina nevadensis biozone in both regions. No such correlation, however, is possible with the Late Ordovician of Anticosti Island in eastern Canada because of the absence of the index Upper Ordovician chitinozoan zonal species of central Nevada such as Belonechitina tenuispinata sp. nov, Ordochitina nevadensis sp. nov. and Nevadachitina vininica gen. nov., sp. nov. in the former area.One new genus, Nevadachitina, and nine new species, Eisenackitina ripae, Belonechitina martinica, Nevadachitina vininica, Nevadachitina praevininica, Ordochitina nevadensis, Belonechitina tenuispinata, Belonechitina parvispinata, Tanuchitina laurentiana, Angochitina hansonica are described and illustrated in this paper and four species are left in open nomenclature.

  18. Ordovician and Silurian acritarch assemblages from the west Leinster and Slievenamon areas of southeast Ireland.

    Science.gov (United States)

    Maziane-Serraj, N; Brück, P M.; Higgs, K T.; Vanguestaine, M

    2000-12-01

    The Lower Palaeozoic sequences west of the Leinster Granite and in the Slievenamon Inlier of southeast Ireland have been palynologically re-investigated. Most of the productive samples yielded sufficient identifiable acritarchs for positive stratigraphical age determinations for several of the formations. The samples also include rare cryptospores, scolecodonts and tubular structures. Previous work in the area west of the Leinster Granite proposed an unbroken succession from Early Ordovician Ribband Group turbidites and volcanics passing up conformably to Early Ordovician to Late Silurian Kilcullen Group. The new palynological data clearly show that the Kilcullen Group in this area is entirely Silurian (Llandovery-early Wenlock) in age, also results obtained from the same group at Slievenamon confirm the previously reported Silurian age. Ordovician acritarchs found in the Kilcullen Group of both study areas are reworked and range in age from late Tremadoc to Llanvirn. The new data reveal a major stratigraphic break between the Ribband Group dated as Early and Middle Ordovician and the Silurian Kilcullen Group. This major break extends some hundreds of kms southwest to the Dingle Peninsula and possibly equates with a similar discontinuity in the Isle of Man to the northeast. This break would thus appear to be a major feature within the northwestern Avalonian margin sequence.

  19. Feeding and development of Nephaspis Oculata (Coleoptera: Coccinellidae) on rugose spiraling whitefly

    Science.gov (United States)

    Nephaspis oculata (Blatchley, 1917) is a whitefly predatory lady beetle which has been studied for its biological control effect on different whiteflies. Here, we studied the feeding rate and development of this beetle on rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin 2004, an i...

  20. Effect of buprofezin and Isaria fumosorosea against rugose spiraling whitefly, 2015

    Science.gov (United States)

    The objective of this study was to evaluate the efficacy of selected insecticides alone or in combination against Aleurodicus rugioperculatus Martin, the rugose spiraling whitefly (RSW), a new invasive pest of ornamentals in Florida. The trial was conducted on an ornamental host, white bird of parad...

  1. Multi-scale measures of rugosity, slope and aspect from benthic stereo image reconstructions.

    Directory of Open Access Journals (Sweden)

    Ariell Friedman

    Full Text Available This paper demonstrates how multi-scale measures of rugosity, slope and aspect can be derived from fine-scale bathymetric reconstructions created from geo-referenced stereo imagery. We generate three-dimensional reconstructions over large spatial scales using data collected by Autonomous Underwater Vehicles (AUVs, Remotely Operated Vehicles (ROVs, manned submersibles and diver-held imaging systems. We propose a new method for calculating rugosity in a Delaunay triangulated surface mesh by projecting areas onto the plane of best fit using Principal Component Analysis (PCA. Slope and aspect can be calculated with very little extra effort, and fitting a plane serves to decouple rugosity from slope. We compare the results of the virtual terrain complexity calculations with experimental results using conventional in-situ measurement methods. We show that performing calculations over a digital terrain reconstruction is more flexible, robust and easily repeatable. In addition, the method is non-contact and provides much less environmental impact compared to traditional survey techniques. For diver-based surveys, the time underwater needed to collect rugosity data is significantly reduced and, being a technique based on images, it is possible to use robotic platforms that can operate beyond diver depths. Measurements can be calculated exhaustively at multiple scales for surveys with tens of thousands of images covering thousands of square metres. The technique is demonstrated on data gathered by a diver-rig and an AUV, on small single-transect surveys and on a larger, dense survey that covers over [Formula: see text]. Stereo images provide 3D structure as well as visual appearance, which could potentially feed into automated classification techniques. Our multi-scale rugosity, slope and aspect measures have already been adopted in a number of marine science studies. This paper presents a detailed description of the method and thoroughly validates it

  2. ToxR of Vibrio cholerae affects biofilm, rugosity and survival with Acanthamoeba castellanii

    Directory of Open Access Journals (Sweden)

    Valeru Soni P

    2012-01-01

    Full Text Available Abstract Background Vibrio cholerae causes the diarrheal disease cholera and utilizes different survival strategies in aquatic environments. V. cholerae can survive as free-living or in association with zooplankton and can build biofilm and rugose colonies. The bacterium expresses cholera toxin (CT and toxin-coregulated pilus (TCP as the main virulence factors. These factors are co-regulated by a transcriptional regulator ToxR, which modulates expression of outer membrane proteins (OmpU and (OmpT. The aims of this study were to disclose the role of ToxR in expression of OmpU and OmpT, biofilm and rugose colony formation as well as in association with the free-living amoeba Acanthamoeba castellanii at different temperatures. Results The toxR mutant V. cholerae produced OmpT, significant biofilm and rugose colonies compared to the wild type that produced OmpU, decreased biofilm and did not form rugoes colonies at 30°C. Interestingly, neither the wild type nor toxR mutant strain could form rugose colonies in association with the amoebae. However, during the association with the amoebae it was observed that A. castellanii enhanced survival of V. cholerae wild type compared to toxR mutant strain at 37°C. Conclusions ToxR does seem to play some regulatory role in the OmpT/OmpU expression shift, the changes in biofilm, rugosity and survival with A. castellanii, suggesting a new role for this regulatory protein in the environments.

  3. Ordovician Basement Hydrocarbon Reservoirs in the Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    YAN Xiangbin; LI Tiejun; ZHANG Tao

    2004-01-01

    Ordovician marine carbonate basement traps are widely developed in the paleo-highs and paleo-slopes in the Tarim Basin. Reservoirs are mainly altered pore-cavity-fissure reservoirs. Oil sources are marine carbonate rocks of the Lower Paleozoic. Thus, the paleo-highs and paleo-slopes have good reservoiring conditions and they are the main areas to explore giant and large-scale oil reservoirs. The main factors for their reservoiring are: (1) Effective combination of fenestral pore-cavity-fracture reservoirs, resulting from multi-stage, multi-cyclic karstification (paleo-hypergene and deep buried) and fracturing, with effective overlying seals, especially mudstone and gypsum mudstone in the Carboniferous Bachu Formation, is essential to hydrocarbon reservoiring and high and stable production; (2) Long-term inherited large rises and multi-stage fracture systems confine the development range of karst reservoirs and control hydrocarbon migration, accumulation and reservoiring; (3) Long-term multi-source hydrocarbon supply, early reservoiring alteration and late charging adjustment are important reservoiring mechanisms and determine the resource structure and oil and gas properties. Favorable areas for exploration of Ordovician carbonate basement hydrocarbon reservoirs in the Tarim Basin are the Akekule rise, Katahe uplift, Hetianhe paleo-high and Yakela faulted rise.

  4. Brachiopod faunas after the end Ordovician mass extinction from South China: Testing ecological change through a major taxonomic crisis

    Science.gov (United States)

    Huang, Bing; Harper, David A. T.; Rong, Jiayu; Zhan, Renbin

    2017-05-01

    Classification of extinction events and their severity is generally based on taxonomic counts. The ecological impacts of such events have been categorized and prioritized but rarely tested with empirical data. The ecology of the end Ordovician extinction and subsequent biotic recovery is tracked through abundant and diverse brachiopod faunas in South China. The spatial and temporal ranges of some 6500 identified specimens, from 10 collections derived from six localities were investigated by network and cluster analyses, nonmetric multidimensional scaling and a species abundance model. Depth zonations and structure of brachiopod assemblages along an onshore-offshore gradient in the late Katian were similar to those in the latest Ordovician-earliest Silurian (post-extinction fauna). Within this ecological framework, deeper-water faunas are partly replaced by new taxa; siliciclastic substrates continued to be dominated by the more 'Ordovician' orthides and strophomenides, shallow-water carbonate environments hosted atrypides, athyridides and pentamerides, with the more typical Ordovician brachiopod fauna continuing to dominate until the late Rhuddanian. The end Ordovician extinctions tested the resilience of the brachiopod fauna without damage to its overall ecological structure; that commenced later at the end of the Rhuddanian.

  5. Redox fluctuations in the Early Ordovician oceans

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary; Gilleaudeau, Geoffrey Jon; Peralta, Silvio

    2017-01-01

    are a potential sink for dissolved Cr in the ocean and could effectively capture the Cr isotope composition of ambient seawater. Thus, the Cr isotopic composition (δ53Cr) of carbonates has the potential to record changes in the oxygenation state of ancient oceans. To test the potential of this system, we measured...... δ53Cr values of limestones and dolostones from an Early Ordovician marine carbonate platform (Cerro La Silla section of the Precordillera, San Juan, Argentina). An increasing number of studies support the hypothesis that the Early Ordovician oceans were stratified with respect to oxygen......, accompanied by exceptionally low Cr concentrations (

  6. Ordovician eunicid polychaetes of Estonia and surrounding areas: review of their distribution and diversification.

    Science.gov (United States)

    Hints, O

    2000-12-01

    Scolecodonts, the jaws of polychaete worms, are common and diverse palynomorphs in the Ordovician rocks of Estonia and surrounding areas. Some 120 apparatus-based species representing about 40 genera have been recorded thus far. Relatively long stratigraphical ranges of the majority of species reflect a low rate of evolution of jawed polychaetes. However, some individual species, as well as structural changes in the assemblages, appear to be useful for stratigraphical purposes. Environmental events like those in the middle Caradoc and late Ashgill had some impact on polychaete faunas, but less than on several other groups. In order to study the spatial distribution of eunicids, faunas of particular intervals of the Ordovician were investigated. Quantitative analysis revealed that polychaete assemblages with a very consistent qualitative and quantitative composition were widespread over long distances within the belts of similar facies conditions in the Baltoscandian Palaeobasin. On the other hand, it appears that species of Ordovician jawed polychaetes were strongly influenced by particular facies, and accordingly well differentiated along the palaeobasin gradient. The decrease in diversity and abundance towards the deeper-water part of the palaeobasin indicates that the majority of Ordovician eunicids preferred relatively shallow-water conditions. The increase in differentiation of environments is accompanied by an increase in differentiation of polychaete assemblages.

  7. The chromium isotopic composition of an Early to Middle Ordovician marine carbonate platform, eastern Precordillera, San Juan, Argentina

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary; Frei, Robert; Gilleaudeau, Geoffrey Jon;

    A broad suite of redox proxy data suggest that despite ocean and atmosphere oxygenation in the late Neoproterozoic, euxinic conditions persisted in the global deep oceans until the at least Ordovician [1,2,3]. Major changes in the sulphur isotopic composition of carbonate associated sulphate and ...

  8. Rugosity grid derived from gridded bathymetry of Tinian Island, Aguijan Island and Tatsumi Bank, Commonwealth of the Northern Marianas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) bathymetry, from three sources: Multibeam bathymetry collected by Coral Reef Ecosystem Division aboard NOAA R/V AHI,...

  9. NOAA TIFF Image - 3m Bathymetric Rugosity, Florida Deep Coral Areas - Lost Coast Explorer - (2011), UTM 17N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 3x3 meter cell size representing the rugosity of several deep coral priority areas off the Atlantic Coast of Florida,...

  10. Rugosity derived from gridded bathymetry of Farallon de Medinilla (FDM), Commonwealth of the Northern Mariana (CNMI), USA.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, aboard NOAA Ship Oscar Elton Sette. Cell values reflect the (surface area) / (planimetric...

  11. Rugosity 10 m grid derived from gridded bathymetry of Maug Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

  12. Rugosity 10 m grid derived from gridded bathymetry of Asuncion Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

  13. Rugosity grid derived from gridded bathymetry Ofu and Olosega Islands of the Manu'a Island group, American Samoa

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard R/V AHI, and bathymetry derived from multispectral IKONOS satellite imagery...

  14. Rugosity 10 m grid derived from gridded bathymetry of Sarigan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hi'ialakai and R/V AHI, using the Benthic Terrain Modeler with...

  15. Rugosity 10 m grid derived from gridded bathymetry of Guguan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

  16. NOAA TIFF Image - 4m Bathymetric Rugosity of Red Snapper Research Areas in the South Atlantic Bight, 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains unified Bathymetric Rugosity GeoTiffs with 4x4 meter cell resolution describing the topography of 15 areas along the shelf edge off the South...

  17. Trace fossils and sedimentary facies from a Late Cambrian-Early Ordovician tide-dominated shelf (Santa Rosita Formation, northwest Argentina): Implications for ichnofacies models of shallow marine successions

    Science.gov (United States)

    Mangano, M.G.; Buatois, L.A.; Acenolaza, G.F.

    1996-01-01

    The Santa Rosita Formation is one the most widely distributed lower Paleozoic units of northwest Argentina. At the Quebrada del Salto Alto section, east of Purmamarca, Jujuy Province, it is represented by four sedimentary facies: thick-bedded planar cross-stratified quartzose sandstones (A), thin-bedded planar cross-stratified quartzose sandstones and mudstones (B), wave-rippled sandstones and bioturbated mudstones (C), and black and greenish gray shales (D). Paleocurrent data, sandstone architecture, and sedimentary structures from facies A and B indicate bipolar/bimodal paleoflows, suggesting the action of tidal currents. The succession is interpreted as that of a tide-dominated shelf, with only secondary influence of wave processes. Trace fossils are restricted to facies B and C. The Cruziana ichnocoenosis is preserved on the soles of thin-bedded planar cross-stratified quartzose sandstones (facies B). This ichnocoenosis consists of Conostichus isp., Cruziana omanica, C. semiplicata, C. cf. tortworthi, Cruziana isp. Helminthopsis abeli, Monomorphichnus bilinearis, M. multilineatus, Palaeophycus tubularis, Rusophycus carbonarius, R. latus, and R. isp. The occurrence of Cruziana semiplicata, C. omanica, C. cf. tortworthi, and Rusophycus latus supports a Late Cambrian-Tremadoc age. Slabbing of Cruziana shows complex interactions between biologic and sedimentologic processes, and suggests a predominance of exhumed traces, washed out and recast by tractive sand deposition. Sandstone soles are densely packed with biogenic structures and exhibit distinctive clusters of Rusophycus isp. that most likely represent trilobite nesting burrows. The Cruziana ichnocoenosis records the resident fauna of a protected, lower intertidal to subtidal interbar setting. The Skolithos ichnocoenosis is represented by high to low density vertical burrows of Skolithos linearis, which extend downwards to the quartzose sandstone soles of facies B and cross the Cruziana ichnocoenosis. The

  18. Rugose atypical Vibrio cholerae O1 El Tor responsible for 2009 cholera outbreak in India.

    Science.gov (United States)

    Chowdhury, Goutam; Bhadra, Rupak K; Bag, Satyabrata; Pazhani, Gururaja P; Das, Bhabatosh; Basu, Pallabi; Nagamani, K; Nandy, Ranjan K; Mukhopadhyay, Asish K; Ramamurthy, Thandavarayan

    2016-10-01

    Vibrio cholerae causes cholera outbreaks in endemic regions where the water quality and sanitation facilities remain poor. Apart from biotype and serotype changes, V. cholerae undergoes phase variation, which results in the generation of two morphologically different variants termed smooth and rugose. In this study, 12 rugose (R-VC) and 6 smooth (S-VC) V. cholerae O1 Ogawa isolates were identified in a cholera outbreak that occurred in Hyderabad, India. Antimicrobial susceptibility results showed that all the isolates were resistant to ampicillin, furazolidone and nalidixic acid. In addition, R-VC isolates were resistant to ciprofloxacin (92 %), streptomycin (92 %), erythromycin (83 %), trimethoprim-sulfamethoxazole (75 %) and tetracycline (75 %). Based on the ctxB gene analysis, all the isolates were identified as El Tor variant with mutation in two positions of ctxB, similar to the classical biotype. The R-VC isolates specifically showed excessive biofilm formation and were comparatively less motile. In addition, the majority of these isolates (~83 %) displayed random mutations in the hapR gene, which encodes haemagglutinin protease regulatory protein. In the PFGE analysis, R-VC and S-VC were placed in distinct clusters but remained clonally related. In the ribotyping analysis, all the R-VC isolates exhibited R-III pattern, which is a prevailing type among the current El Tor isolates. A hapR deletion mutant generated using an S-VC isolate expressed rugose phenotype. To our knowledge, this is the first report on the association of rugose V. cholerae O1 in a large cholera outbreak with extended antimicrobial resistance and random mutations in the haemagglutinin protease regulatory protein encoding gene (hapR).

  19. Cartographic Production for the FLaSH Map Study: Generation of Rugosity Grids, 2008

    Science.gov (United States)

    Robbins, Lisa L.; Knorr, Paul O.; Hansen, Mark

    2010-01-01

    Project Summary This series of raster data is a U.S. Geological Survey (USGS) Data Series release from the Florida Shelf Habitat Project (FLaSH). This disc contains two raster images in Environmental Systems Research Institute, Inc. (ESRI) raster grid format, jpeg image format, and Geo-referenced Tagged Image File Format (GeoTIFF). Data is also provided in non-image ASCII format. Rugosity grids at two resolutions (250 m and 1000 m) were generated for West Florida shelf waters to 250 m using a custom algorithm that follows the methods of Valentine and others (2004). The Methods portion of this document describes the specific steps used to generate the raster images. Rugosity, also referred to as roughness, ruggedness, or the surface-area ratio (Riley and others, 1999; Wilson and others, 2007), is a visual and quantitative measurement of terrain complexity, a common variable in ecological habitat studies. The rugosity of an area can affect biota by influencing habitat, providing shelter from elements, determining the quantity and type of living space, influencing the type and quantity of flora, affecting predator-prey relationships by providing cover and concealment, and, as an expression of vertical relief, can influence local environmental conditions such as temperature and moisture. In the marine environment rugosity can furthermore influence current flow rate and direction, increase the residence time of water in an area through eddying and current deflection, influence local water conditions such as chemistry, turbidity, and temperature, and influence the rate and nature of sedimentary deposition. State-of-the-art computer-mapping techniques and data-processing tools were used to develop shelf-wide raster and vector data layers. Florida Shelf Habitat (FLaSH) Mapping Project (http://coastal.er.usgs.gov/flash) endeavors to locate available data, identify data gaps, synthesize existing information, and expand our understanding of geologic processes in our dynamic

  20. Accumulation process and model for the Ordovician buried hill reservoir in the western Lunnan area, the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Ordovician buried hill reservoir in the western Lunnan area, a type of dissolved fracture and cavernous reservoir, is mainly composed of heavy oil. The oil is the mixture sourcing from the Middle-Lower Cambrian and Middle-Lower Ordovician, with three stages of pool forming process: (1) the destruction and parallel migration/accumulation during the late Caledonian to early Hercynian; (2) the oil and gas accumulation during the late Hercynian characterized by adjustment upward along faults and parallel migration/accumulation; (3) the formation of heavy oil during the latest Hercynian. The Ordovician buried hill reservoir is affected by the diffusion of light oil and gas but had no hydrocarbon charging during the late Yanshan period to Himalayan period, but in this period, formed the association of heavy oil and dissolved gas cracked from crude oil with dry coefficient of 0.91-0.96. The study on accumulation process of the Ordovician buried hill reservoir has important implications for the exploration potential of early oil and gas accumulation in the cratonic area of the Tarim Basin.

  1. Cambrian to Lower Ordovician complexes of the Kokchetav Massif and its fringing (Northern Kazakhstan): Structure, age, and tectonic settings

    Science.gov (United States)

    Degtyarev, K. E.; Tolmacheva, T. Yu.; Tretyakov, A. A.; Kotov, A. B.; Shatagin, K. N.

    2016-01-01

    A comprehensive study of the Lower Palaeozoic complexes of the Kokchetav Massif and its fringing has been carried out. It has allowed for the first time to discover and investigate in detail the stratified and intrusive complexes of the Cambrian-Early Ordovician. Fossil findings and isotope geochronology permitted the determination of their ages. The tectonic position and internal structures of those complexes have also been defined and their chemical features have been analyzed as well. The obtained data allowed us to put forward a model of the geodynamic evolution of Northern Kazakhstan in the Late Ediacaran-Earliest Ordovician. The accumulation of the oldest Ediacaran to Earliest Cambrian siliciclastics and carbonates confined to the Kokchetav Massif and its fringing occurred in a shallow shelf environment prior to its collision with the Neoproterozoic Daut island arc: complexes of the latter have been found in the northeast of the studied area. The Early Cambrian subduction of the Kokchetav Massif under the Daut island arc, their following collision and exhumation of HP complexes led to the formation of rugged ground topography, promoting deposition of siliceous-clastic and coarse clastic units during the Middle to early Late Cambrian. Those sediments were mainly sourced from eroded metamorphic complexes of the Kokchetav Massif basement. At the end of the Late Cambrian to the Early Ordovician within the boundaries of the massif with the Precambrian crust, volcanogenic and volcano-sedimentary units along with gabbros and granites with intraplate affinities were formed. Simultaneously in the surrounding zones, which represent relics of basins with oceanic crust, N-MORB- and E-MORB-type ophiolites were developed. These complexes originated under extensional settings occurred in the majority of the Caledonides of Kazakhstan and Northern Tian Shan. In the Early Floian Stage (Early Ordovician) older heterogeneous complexes were overlain by relatively monotonous

  2. Carboniferous-Permian rugose coral Cyathaxonia faunas in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Cyathaxonia faunas are widely distributed in the Carboniferous and Permian strata in China.The fauna in China contains 12 families and 40 genera,and can be recognized as three episodes from Early Carboniferous to the end-Permian in terms of their occurrence and composition:1) Mississippian;2) Pennsylvanian-Early Permian;3) Middle Permian-Late Permian.They were relatively abundant in episodes 1 and 2.A decrease of family Antiphyllidae and an increase of family Hapsiphyllidae can be observed from Early Carboniferous to the end-Permian.Two case studies are given to illustrate the bio-facies of the Cyathaxonia faunas,which are from the Mississippian of Baoshan,West Yunnan and the Mississippian of Chaohu,South Anhui.In both areas,Cyathaxonia faunas occur just below the large dissepimented solitary and compound coral assemblages in a continuous sequence in a single section,which implies that the occurrence of these small,non-dissepimented solitary corals is not strictly related with Gondwanan or Peri-gondwanan cold water environment,but might be controlled by such benthic conditions as deeper,mud-rich,quieter,and darker sedimentary environments.

  3. Early Paleozoic paleogeography of the northern Gondwana margin: new evidence for Ordovician-Silurian glaciation

    Science.gov (United States)

    Semtner, A.-K.; Klitzsch, E.

    1994-12-01

    During the Early Paleozoic, transgressions and the distribution of sedimentary facies on the northern Gondwana margin were controlled by a regional NNW-SSE to almost north-south striking structural relief. In Early Silurian times, a eustatic highstand enabled the sea to reach its maximum southward extent. The counterclockwise rotation of Gondwana during the Cambrian and Early Ordovician caused the northern Gondwana margin to shift from intertropical to southern polar latitudes in Ordovician times. Glacial and periglacial deposits are reported from many localities in Morocco, Algeria, Niger, Libya, Chad, Sudan, Jordan and Saudi Arabia. The Late Ordovician glaciation phase was followed by a period of a major glacioeustatic sea-level rise in the Early Silurian due to the retreat of the ice-cap. As a consequence of the decreasing water circulation in the basin centers (Central Arabia, Murzuk- and Ghadames basins), highly bituminous euxinic shales were deposited. These shales are considered to be the main source rock of Paleozoic oil and gas deposits in parts of Saudi Arabia, Libya and Algeria. The following regression in the southern parts of the Early Silurian sea was probably caused by a second glacial advance, which was mainly restricted to areas in Chad, Sudan and Niger. Evidence for glacial activity and fluvioglacial sedimentation is available from rocks overlying the basal Silurian shale in north-east Chad and north-west Sudan. The Early Silurian ice advance is considered to be responsible for the termination of euxinic shale deposition in the basin centers.

  4. Revision of annulated orthoceridan cephalopods of the Baltoscandic Ordovician

    Directory of Open Access Journals (Sweden)

    B. Kröger

    2006-02-01

    Full Text Available The annulated orthoceridans of the Middle and Late Ordovician of Baltoscandia are described and their systematic frame is revised. The revision of these nautiloids, which are part of the Orthocerida and Pseudorthocerida, is based on the investigation of characters of the septal neck, the siphuncular tube, and the apex. An unequivocal terminology of these characters is suggested and applied. The shape of the septal neck and the siphuncular tube are described for the first time in Palaeodawsonoceras n. gen., Striatocycloceras n. gen., Dawsonoceras fenestratum Eichwald, 1860, and Gorbyoceras textumaraneum (Roemer, 1861. Ctenoceras sweeti n. sp. is erected. The apex of Dawsonoceras barrandei Horný, 1956 is figured and described for the first time. The distribution of the character states of the apex and the septal neck support the emendation of the families Orthoceratidae, Dawsonoceratidae, and Proteoceratidae. The analysis shows also that the families Kionoceratidae, and Leuroceratidae must be refused because they represent not natural groups. However, it is also shown that the present knowledge is not sufficient to establish an unequivocal classification of the Middle, and Late Ordovician annulate cephalopods. Die orthoceriden Cephalopoden des Mittleren bis Späten Ordoviziums im Baltoskandium werden beschrieben und revidiert. Die Revision dieser Cephalopoden, welche zu den Orthocerida und Pseudorthocerida gehören, stützt sich auf die Untersuchung der Apikalenden, der Septalduten und der Form der Siphonalröhre. Eine eindeutige Terminologie für diese Merkmale wird vorgeschlagen und angewandt. Die Form der Septalduten und der Siphonalröhre von Palaeodawsonoceras n. gen., Striatocycloceras n. gen., Dawsonoceras fenestratum, Eichwald, 1860 und Gorbyoceras textumaraneum (Roemer, 1861 wird erstmals beschrieben. Die Art Ctenoceras sweeti n. sp. wird aufgestellt. Der Apex von Dawsonoceras barrandei Horný, 1956 wird erstmals beschrieben und

  5. Appalachian Blue Ridge cover sequence ranges at least into the Ordovician

    Science.gov (United States)

    Tull, James F.; Ausich, William I.; Groszos, Mark S.; Thompson, Troy W.

    1993-03-01

    The first direct evidence that stratified rocks of the central core of the southern Appalachian Blue Ridge range in age into the Paleozoic comes from a pelmatozoan echinoderm column discovered within a unit directly above the Murphy Marble in North Carolina. Before this discovery most geologists had considered all stratified rocks of the Blue Ridge east of the frontal imbricate thrust blocks to be Late Proterozoic or Early Cambrian(?). The echinoderm fragment is in a lower amphibolite facies interbedded mica schist-impure marble zone that lies directly above the Murphy Marble. Rocks above the Murphy Marble are dominantly turbiditic metaclastic rocks with minor carbonate and metavolcanic rocks, interpreted as having formed within a successor basin unconformably above upper Precambrian rift facies and lower Paleozoic drift facies rocks of the Laurentian passive margin. An upper bound for the age of the successor basin in the Murphy belt has not been established; similar sequences in the Talladega belt to the southwest, and possibly the Foothills belt to the west, range at least into the Devonian. Most Appalachian tectonic models assert that during the Taconic orogeny a Middle Ordovician synorogenic clastic wedge, now located in the easternmost Tennessee foreland salient, was derived by erosion from the metamorphosed pre-Ordovician Blue Ridge basement and cover sequence to the east, which was uplifted as part of an advancing Taconic crystalline thrust wedge. The presence of Ordovician or younger rocks described here, which were deposited east of the proposed Taconic orogenic front, suggests the need to modify models for Taconic clastic wedge formation in the southern Appalachians. The results presented here also suggest that peak metamorphism in the region was post-Ordovician, and thus was probably not contemporaneous with the Taconic orogeny, as previously thought.

  6. Sedimentary facies and palaeogeography during the middle and late Darriwilian to the early Katian (Ordovician) and hydrocarbon exploration in central and southern Hunan%湘中湘南地区奥陶纪达瑞威尔中晚期-凯迪早期岩相古地理及其油气地质意义

    Institute of Scientific and Technical Information of China (English)

    葛祥英; 牟传龙; 周恳恳; 梁薇

    2011-01-01

    湘中湘南地区在早古生代时期,由于受海平面变化以及全球古气候的影响,形成了有利于烃源岩形成的沉积环境.笔者通过对湘中湘南地区的奥陶纪达瑞威尔中晚期-凯迪早期开展沉积相、岩相古地理和油气地质等研究,结合前人所取得的相关研究成果,将该区划分为陆架相、盆地相和陆架边缘相.陆架相主要由砂质板岩、砂岩、黑色页岩和硅质岩组成;陆架边缘相为粉砂-细粒石英砂岩、长石石英砂岩夹条带状板岩、炭质板岩和硅质岩等组成;而盆地相为一套炭质页岩和硅质岩组成的黑色岩系,代表了一种平静还原的滞流缺氧环境.该套岩性有机质含量高,具较高的生烃潜力,且分布范围广,是湘中湘南地区达瑞威尔-凯迪阶的富烃沉积区,也是下一步油气地质调查和勘探的重要层位.%The areas of central and southern Hunan sandwiched between the Yangtze and Cathaysian landmasses are believed to be the favourable sedimentary environments for the formation of source rocks due to the sea-level changes and global palaeoclimatic changes during the Early Palaeozoic. The middle and late Darriwilian to the early Katian ( Ordovician) sedimentary strata dominantly consist of the Yanxi and Modaoxi Formations in central Hunan, and Baimachong and Shuangjiakou Formations in southern Hunan, and may be divided, on the basis of sedimentary facies and palaeogeography and petroleum geology, into continental shelf facies, basin facies and continental shelf-margin facies. The continental shelf facies is made up of sandy slate, sandstone, black shale and siliceous rocks. The continental shelf-margin facies is built up of silty to fine-grained quartz sandstone and feldspathic quartz sandstone, intercalated with banded slate, carbonaceous slate and siliceous rocks. The basin facies is assembled by a succession of black rock series including carbonaceous shale and siliceous rocks, representing

  7. Migration, filling history and geochemical characteristics of Ordovician natural gases in the Tahe Oilfield, Tarim Basin, Northwest China

    Institute of Scientific and Technical Information of China (English)

    WANG Jie; LIU Wenhui; QIN Jianzhong; LIU Keyu; GU Yi

    2009-01-01

    Ordovician natural gases in the Tahe Oilfield are composed predominantly of hydrocarbon gases dominated by methane with a significant amount of heavy hydrocarbon gas component. The non-hydrocarbon gases include N2, CO2 and minor H2S. The Ordovician natural gases are believed to have originated from the same source rocks, and are composite of gases differing in thermal maturity. Carbon dioxide was derived from thermal metamorphism of Ordovician carbonate rocks. The generation of natural gases involves multiple stages from mature normal oil and condensate-associated gas to thermally cracked gas at the maturity to over-maturity stages. In the main part of the Tahe Oilfield, the Ordovician natural gases appear to be filled in two major phases with a typical petroleum-associated gas from southeast to northwest and from east to west in the early stage; and a thermally cracked gas from east to west in the late stage. At the same time, the oil/gas filling boundary has been primarily established between the two stages.

  8. The entomopathogenic fungus Isaria fumosorosea and its compatibility with buprofezin: effects on the rugose spiraling whitefly Aleurodicus rugioperculatus

    Science.gov (United States)

    The gumbo limbo or rugose spiraling whitefly is a new invasive pest of palms, woody ornamentals, and fruits in Florida. The pathogenicity of a naturally occurring entomopathogenic fungus, Isaria fumosorosea (PFR 97) is well known for its activity against commonly found whiteflies species in the regi...

  9. The ages and tectonic setting of the Faja Eruptiva de la Puna Oriental, Ordovician, NW Argentina

    Science.gov (United States)

    Bahlburg, Heinrich; Berndt, Jasper; Gerdes, Axel

    2016-07-01

    linked to the Oclóyic orogeny in the Late Ordovician. The plutons intruded very likely in a sinistral strike-slip regime after the main folding phase of the Oclóyic orogeny had deformed the Ordovician sedimentary country rocks.

  10. From northern Gondwana passive margin to arc dismantling: a geochemical discrimination of Ordovician volcanisms (Sardinia, Italy)

    Science.gov (United States)

    Gaggero, L.; Oggiano, G.; Buzzi, L.; Funedda, A.

    2009-04-01

    palaeontological constraints, as it post-dates the Sarrabese (i.e. Sardic) unconformity and pre-dates the Upper Ordovician transgression. It consists of basaltic - andesites and abundant andesites and rhyolites. The negative Ta-, Nb-, Sr-, P-, Yb- and Ti-anomalies in mantle-normalized spiderdiagrams and Th/Ta compare with volcanic rocks from active continental margins. Andesite and dacite samples reveal Sr and Nd isotopic compositions consistent with a less depleted mantle source than rhyolites (epsilon Nd 465 Ma = -3.03 to -5.75; 87Sr/86Sr 465 Ma = 0.70931-0.71071). The positive epsilon Nd 465 Ma values of rhyolites (+1.15 to +2.42) suggest that their precursors, with a crustal residence age of ~1 Ga (TDM), were derived from a long-term depleted mantle source. On the whole, the isotopic data for Mid Ordovician volcanites suggest partial melting of an isotopically heterogeneous mantle. The bimodal suite has been unanimously interpreted as a marker of the Rheic ocean subduction. An Upper Ordovician transitional to alkalic volcanic activity is documented both in the foreland, and in the external and internal nappes (Di Pisa et al. 1992). The Late Ordovician alkalic mafic suite (440 ± 1.7 Ma) i.e. the Ordovician-Silurian boundary, occurs as sills, epiclastites and lava flows within the post-Caradocian transgressive sequence. The volcanic rocks are characterized by fractionation of REEs (LaCN/YbCN ~ 4.4-13), variable LILE abundances and significant Ta, Nb and LREE enrichments. Th/Ta in the range 1-2 and La/Nb Morena Zone (Évora-Aracena metamorphic belt, SW Iberian Massif): Sm-Nd isotopes and SHRIMP zircon U-Th-Pb geochronology. Tectonophysics, 461, 91-113. Etxebarria M., Chalot-Prat F., Apraiz A., Ehuiluz L. (2006) Birth of a volcanic passive margin in Cambrian time: rift paleogeography of the Ossa - Morena Zone, SW Spain. Precambrian Research, 147, 366-386. Leone F., Hamman W., Laske R., Serpagli E., Villas E. (1991) Lithostratigraphic units and biostratigraphy of the post

  11. Inclusion bodies induced by bean rugose mosaic virus seen under light microscopy

    Directory of Open Access Journals (Sweden)

    Carmen Rivera

    2000-12-01

    Full Text Available Two types of inclusion bodies were consistently observed under light microscopy in bean (Phaseolus vulgaris leaf tissue infected with bean rugose mosaic virus (BRMV, a species of the genus Comovirus, family Comoviridae. One type consisted of vacuolated inclusions found mainly in the cytoplasm of epidermal cells. The other type consisted of abundant crystalloid inclusions of different sizes and shapes found consistently in glandular hairs, guard cells, phloem tissue, xylem elements and occasionally in epidermal and mesophyll tissues. The two types of inclusion bodies stained with Azure A and Luxol Brilliant Green Bl-Calcomine Orange 2RS (O-G, and were similar to those seen to be caused by other species of comoviruses.Se observaron dos tipos de inclusiones virales, mediante microscopia de luz, en hojas de plantas de frijol (Phaseolus vulgaris previamente infectadas con el virus del mosaico rugoso del frijol ("bean rugose mosaic comovirus", BRMV, especie del género Comovirus, familia Comoviridae. Se hallaron inclusiones vesiculadas, principalmente en el citoplasma de células de la epidermis, y abundantes inclusiones cristalinas de diferentes formas y tamaños siempre en células guarda, tricomas glandulares, floema, elementos del xilema y ocasionalmente en células epidérmicas y del mesófilo. Ambos tipos de inclusiones tiñeron con Azure A y con la tinción, verde naranja (Luxol Brilliant Green BL-Calcomine Orange 2 RS conocida como OG, y son similares a las inclusiones inducidas por otras especies del género Comovirus.

  12. Rugose corals across the Devonian-Carboniferous boundary in NW Turkey

    Directory of Open Access Journals (Sweden)

    Julien Denayer

    2016-02-01

    Full Text Available An uppermost Famennian (Strunian coral assemblage has been recovered in the middle part of the Yılanlı Formation of the Istanbul Zone (Zonguldak and Bartın areas, NW Turkey. In the Bartın area, the studied fossiliferous interval corresponds to a c. 30 m-thick unit of bioclastic to peloidal wackestone to packstone grading to grainstone and including two stromatoporoid biostromes. In the Zonguldak area, 60 km westward, the bioclastic facies is dominant. The rugose corals are mainly solitary taxa belonging to the genera Campophyllum, Bounophyllum, Amplexocarinia, and ?Metriophyllum, and only one colonial genus occurs: Pseudoendophyllum. This fauna is similar to that documented in Europe. The campophyllids and dibunophyllids are the main component of the uppermost Famennian assemblages in S Belgium, N France, W Germany, NW and S Poland. The endophyllids occur in S Poland, Novaya Zemlya, and in the Ural Mountains. The Istanbul Zone is supposed to be situated in the central part of the Palaeotethys Ocean, along the southern margin of Laurussia during the uppermost Devonian and Carboniferous. The rugose corals indicate some relationship with the eastern part of Laurussia, or that both areas were under a common marine influence at this time. The global Hangenberg event was not recognized in the Turkish localities, except for the disappearance of the corals, occurring less than 19 m below the Devonian–Carboniferous boundary based on the foraminifers. There is no major facies change through the boundary and the first Carboniferous corals (small Uralinia and Caninophyllum appear 6 m above the D–C boundary. The new species Caninophyllum charli sp. nov. is described from the upper part of the lower Tournaisian.

  13. The cabABC Operon Essential for Biofilm and Rugose Colony Development in Vibrio vulnificus

    Science.gov (United States)

    Park, Jin Hwan; Jo, Youmi; Jang, Song Yee; Kwon, Haenaem; Irie, Yasuhiko; Parsek, Matthew R.; Kim, Myung Hee; Choi, Sang Ho

    2015-01-01

    A transcriptome analysis identified Vibrio vulnificus cabABC genes which were preferentially expressed in biofilms. The cabABC genes were transcribed as a single operon. The cabA gene was induced by elevated 3′,5′-cyclic diguanylic acid (c-di-GMP) and encoded a calcium-binding protein CabA. Comparison of the biofilms produced by the cabA mutant and its parent strain JN111 in microtiter plates using crystal-violet staining demonstrated that CabA contributed to biofilm formation in a calcium-dependent manner under elevated c-di-GMP conditions. Genetic and biochemical analyses revealed that CabA was secreted to the cell exterior through functional CabB and CabC, distributed throughout the biofilm matrix, and produced as the biofilm matured. These results, together with the observation that CabA also contributes to the development of rugose colony morphology, indicated that CabA is a matrix-associated protein required for maturation, rather than adhesion involved in the initial attachment, of biofilms. Microscopic comparison of the structure of biofilms produced by JN111 and the cabA mutant demonstrated that CabA is an extracellular matrix component essential for the development of the mature biofilm structures in flow cells and on oyster shells. Exogenously providing purified CabA restored the biofilm- and rugose colony-forming abilities of the cabA mutant when calcium was available. Circular dichroism and size exclusion analyses revealed that calcium binding induces CabA conformational changes which may lead to multimerization. Extracellular complementation experiments revealed that CabA can assemble a functional matrix only when exopolysaccharides coexist. Consequently, the combined results suggested that CabA is a structural protein of the extracellular matrix and multimerizes to a conformation functional in building robust biofilms, which may render V. vulnificus to survive in hostile environments and reach a concentrated infective dose. PMID:26406498

  14. The cabABC Operon Essential for Biofilm and Rugose Colony Development in Vibrio vulnificus.

    Science.gov (United States)

    Park, Jin Hwan; Jo, Youmi; Jang, Song Yee; Kwon, Haenaem; Irie, Yasuhiko; Parsek, Matthew R; Kim, Myung Hee; Choi, Sang Ho

    2015-09-01

    A transcriptome analysis identified Vibrio vulnificus cabABC genes which were preferentially expressed in biofilms. The cabABC genes were transcribed as a single operon. The cabA gene was induced by elevated 3',5'-cyclic diguanylic acid (c-di-GMP) and encoded a calcium-binding protein CabA. Comparison of the biofilms produced by the cabA mutant and its parent strain JN111 in microtiter plates using crystal-violet staining demonstrated that CabA contributed to biofilm formation in a calcium-dependent manner under elevated c-di-GMP conditions. Genetic and biochemical analyses revealed that CabA was secreted to the cell exterior through functional CabB and CabC, distributed throughout the biofilm matrix, and produced as the biofilm matured. These results, together with the observation that CabA also contributes to the development of rugose colony morphology, indicated that CabA is a matrix-associated protein required for maturation, rather than adhesion involved in the initial attachment, of biofilms. Microscopic comparison of the structure of biofilms produced by JN111 and the cabA mutant demonstrated that CabA is an extracellular matrix component essential for the development of the mature biofilm structures in flow cells and on oyster shells. Exogenously providing purified CabA restored the biofilm- and rugose colony-forming abilities of the cabA mutant when calcium was available. Circular dichroism and size exclusion analyses revealed that calcium binding induces CabA conformational changes which may lead to multimerization. Extracellular complementation experiments revealed that CabA can assemble a functional matrix only when exopolysaccharides coexist. Consequently, the combined results suggested that CabA is a structural protein of the extracellular matrix and multimerizes to a conformation functional in building robust biofilms, which may render V. vulnificus to survive in hostile environments and reach a concentrated infective dose.

  15. The cabABC Operon Essential for Biofilm and Rugose Colony Development in Vibrio vulnificus.

    Directory of Open Access Journals (Sweden)

    Jin Hwan Park

    2015-09-01

    Full Text Available A transcriptome analysis identified Vibrio vulnificus cabABC genes which were preferentially expressed in biofilms. The cabABC genes were transcribed as a single operon. The cabA gene was induced by elevated 3',5'-cyclic diguanylic acid (c-di-GMP and encoded a calcium-binding protein CabA. Comparison of the biofilms produced by the cabA mutant and its parent strain JN111 in microtiter plates using crystal-violet staining demonstrated that CabA contributed to biofilm formation in a calcium-dependent manner under elevated c-di-GMP conditions. Genetic and biochemical analyses revealed that CabA was secreted to the cell exterior through functional CabB and CabC, distributed throughout the biofilm matrix, and produced as the biofilm matured. These results, together with the observation that CabA also contributes to the development of rugose colony morphology, indicated that CabA is a matrix-associated protein required for maturation, rather than adhesion involved in the initial attachment, of biofilms. Microscopic comparison of the structure of biofilms produced by JN111 and the cabA mutant demonstrated that CabA is an extracellular matrix component essential for the development of the mature biofilm structures in flow cells and on oyster shells. Exogenously providing purified CabA restored the biofilm- and rugose colony-forming abilities of the cabA mutant when calcium was available. Circular dichroism and size exclusion analyses revealed that calcium binding induces CabA conformational changes which may lead to multimerization. Extracellular complementation experiments revealed that CabA can assemble a functional matrix only when exopolysaccharides coexist. Consequently, the combined results suggested that CabA is a structural protein of the extracellular matrix and multimerizes to a conformation functional in building robust biofilms, which may render V. vulnificus to survive in hostile environments and reach a concentrated infective dose.

  16. NOAA TIFF Image - 3m Bathymetric Rugosity, Florida Deep Coral Areas (Jacksonville) - Lost Coast Explorer - (2011), UTM 17N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 3x3 meter cell size representing the rugosity of several deep coral priority areas off the Atlantic Coast of Florida,...

  17. NOAA TIFF Image - 10m Bathymetric Rugosity, South Atlantic Bight - Deep Coral Priority Areas - NOAA Ship Nancy Foster - (2007), UTM 17N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 10x10 meter cell size representing the rugosity of several deep coral priority areas off the South Atlantic Bight,...

  18. Rugosity 10 m grid derived from gridded bathymetry of Farallon de Pajaros (Uracas) Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

  19. Rugosity grid derived from gridded bathymetry of of Galvez Bank, South Galvez Bank, and 11-Mile Reef, Territory of Guam, USA.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, aboard NOAA Ship Oscar Elton Sette. Cell values reflect the (surface area) / (planimetric...

  20. NOAA TIFF Image - 10m Bathymetric Rugosity, South Atlantic Bight - Deep Coral Priority Areas - NOAA Ship Nancy Foster - (2009), UTM 17N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 10x10 meter cell size representing the rugosity of several deep coral priority areas off the South Atlantic Bight,...

  1. NOAA TIFF Image - 10m Bathymetric Rugosity, South Atlantic Bight - Deep Coral Priority Areas - NOAA Ron Brown - (2010), UTM 17N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 10x10 meter cell size representing the rugosity of several deep coral priority areas off the South Atlantic Bight,...

  2. Ordovician sponges (Porifera and other silicifications from Baltica in Neogene and Pleistocene fluvial deposits of the Netherlands and northern Germany

    Directory of Open Access Journals (Sweden)

    Rhebergen, Freek

    2009-03-01

    Full Text Available Fluvial deposits of Miocene to Early Pleistocene age in Germany and the Netherlands were laid down in the delta of the Eridanos River System, but the exact provenance of this material continues to be a subject of discussion. The aim of the present study is twofold. Firstly, a comparison of Ordovician sponges in these deposits with those from northern Estonia and the St Petersburg region (Russia demonstrates that these erratics originated from the drainage area of the Pra Neva, a tributary of the Eridanos. Secondly, the importance of Late Ordovician silicified boulders, which yield forms of preservation that are unknown in comparable fossils, preserved in situ, is outlined. Some recommendations for future studies are made.

  3. Effect of the Ordovician paleogeography on the (instability of the climate

    Directory of Open Access Journals (Sweden)

    A. Pohl

    2014-11-01

    Full Text Available The Ordovician Period (485–443 Ma is characterized by abundant evidence for continental-sized ice sheets. Modeling studies published so far require a sharp CO2 drawdown to initiate this glaciation. They mostly used non-dynamic slab mixed-layer ocean models. Here, we use a general circulation model with coupled components for ocean, atmosphere, and sea ice to examine the response of Ordovician climate to changes in CO2 and paleogeography. We conduct experiments for a wide range of CO2 (from 16 to 2 times the preindustrial atmospheric CO2 level (PAL and for two continental configurations (at 470 and at 450 Ma mimicking the Middle and the Late Ordovician conditions. We find that the temperature-CO2 relationship is highly non-linear when ocean dynamics are taken into account. Two climatic modes are simulated as radiative forcing decreases. For high CO2 concentrations (≥ 12 PAL at 470 Ma and ≥ 8 PAL at 450 Ma, a relative hot climate with no sea ice characterizes the warm mode. When CO2 is decreased to 8 PAL and 6 PAL at 470 and 450 Ma, a tipping point is crossed and climate abruptly enters a runaway icehouse leading to a cold mode marked by the extension of the sea ice cover down to the mid-latitudes. At 450 Ma, the transition from the warm to the cold mode is reached for a decrease in atmospheric CO2 from 8 to 6 PAL and induces a ~9 °C global cooling. We show that the tipping point is due to the existence of a 95% oceanic Northern Hemisphere, which in turn induces a minimum in oceanic heat transport located around 40° N. The latter allows sea ice to stabilize at these latitudes, explaining the potential existence of the warm and of the cold climatic modes. This major climatic instability potentially brings a new explanation to the sudden Late Ordovician Hirnantian glacial pulse that does not require any large CO2 drawdown.

  4. An Ordovician variation on Burgess Shale-type biotas.

    Science.gov (United States)

    Botting, Joseph P; Muir, Lucy A; Jordan, Naomi; Upton, Christopher

    2015-04-24

    The Cambrian Burgess Shale-type biotas form a globally consistent ecosystem, usually dominated by arthropods. Elements of these communities continued into the Early Ordovician at high latitude, but our understanding of ecological changes during the Great Ordovician Biodiversification Event (GOBE) is currently limited by the paucity of Ordovician exceptionally preserved open-marine faunas. Here we clarify the early stages of the GOBE by describing a new open-marine Konservat-Lagerstätte from the Early Ordovician of Wales. The Afon Gam Biota includes many lineages typical of the Cambrian Burgess Shale-type biotas, but the most abundant groups were sponges, algae and worms, with non-trilobite arthropods being unexpectedly rare. Labile tissues occur abundantly in the sponges and are also present in other groups, including brachiopods and hyoliths. Taphonomic biases are considered and rejected as explanations for arthropod rarity; the preserved biota is considered to be an approximation to the original community composition. We note that other exceptionally preserved communities in the Welsh Ordovician are also sponge-dominated, suggesting a regional change in benthic ecology during the early stages of the GOBE.

  5. Redox conditions and marine microbial community changes during the end-Ordovician mass extinction event

    Science.gov (United States)

    Smolarek, Justyna; Marynowski, Leszek; Trela, Wiesław; Kujawski, Piotr; Simoneit, Bernd R. T.

    2017-02-01

    The end-Ordovician (Hirnantian) crisis is the first globally distinct extinction during the Phanerozoic, but its causes are still not fully known. Here, we present an integrated geochemical and petrographic analysis to understand the sedimentary conditions taking place before, during and after the Late Ordovician ice age. New data from the Zbrza (Holy Cross Mountains) and Gołdap (Baltic Depression) boreholes shows that, like in other worldwide sections, the total organic carbon (TOC) content is elevated in the upper Katian and uppermost Hirnantian to Rhudannian black shales, but depleted (below 1%) during most of the Hirnantian. Euxinic conditions occurred in the photic zone in both TOC-rich intervals. This is based on the maleimide distribution, occurrence of aryl isoprenoids and isorenieratane, as well as a dominance of tiny pyrite framboids. Euxinic conditions were interrupted by the Hirnantian regression caused by glaciation. Sedimentation on the deep shelf changed to aerobic probably due to intense thermohaline circulation. Euxinia in the water column occurred directly during the time associated with the second pulse of the mass extinction with a termination of the end-Ordovician glaciation and sea level rise just at the Ordovician/Silurian (O/S) boundary. In contrast, we suggest based on inorganic proxies that bottom water conditions were generally oxic to dysoxic due to upwelling in the Rheic Ocean. The only episode of seafloor anoxia in the Zbrza basin was found at the O/S boundary, where all inorganic indicators showed elevated values typical for anoxia (U/Th > 1.25; V/Cr > 4.25; V/(V + Ni): 0.54-0.82 and Mo > 10-25 ppm). Significant differences in hopanes to steranes ratio and in C27-C29 sterane distribution between the Katian, Rhudannian and Hirnantian deposits indicate changes in marine microbial communities triggered by sharp climate change and Gondwana glaciation. The increase from biomarkers of cyanobacteria (2α-methylhopanes) after the O

  6. Sm-Nd isotopic compositions of Cambrian-Ordovician strata at the Jinggangshan area in Jiangxi Province:Tectonic implications

    Institute of Scientific and Technical Information of China (English)

    SHEN WeiZhou; LING HongFei; SHU LiangShu; ZHANG FangRong; XIANG Lei

    2009-01-01

    Whole-rock Sm-Nd Isotopes were investigated for Cambrian-Ordovician strata from the Jinggangshan area beTween the Yangtze Block and Cathysla Block in South China. These strata were deposited as a greatly thick unit of muddy-sandy laminas with intercalated carbonate and organic carbon-bearing layers. They have low ε(t) values of -13.9 to -7.9 and old Nd model ages of 1842 to 2375 Ma. In t-tdiagram, they are far away from the concordant line but fall within the evolution zone of the Proterozoic crust of South China. This indicates that the Cambrian-Ordovician strata are mainly composed of mat-ters eroded from ancient Paleoproterozoic crust that may mainly consist of continental-derived detrital sediments with high maturity in the Cathyaia Block. However, the Ordovician Jueshangou Formation and Dui'erehi Formation have ε(t) values of -10.5 and -7.9 at the higher end of the above range and Nd model ages of 1842 to 2059 Ma at the lower end of the above range. This suggests involvement of more detritus that were eroded from the relatively juvenile crust from Late Paleoproterozoic to the Early Neoproterozoic. All the Nd model ages for the Cambrian-Ordovlcian sedimentary rocks in the Cathysia Block and the southeastern margin of the Yangtze Block are older than 1800 Ma, suggesting that no material from the Early Paleozoic depleted mantle-derived magmas was involved in these regions.

  7. A sulfidic driver for the end-Ordovician mass extinction

    DEFF Research Database (Denmark)

    Hammarlund, Emma; Dahl, Tais Wittchen; Harper, David Alexander Taylor

    2012-01-01

    The end-Ordovician extinction consisted of two discrete pulses, both linked, in various ways, to glaciation at the South Pole. The first phase, starting just below the Normalograptus extraordinarius Zone, particularly affected nektonic and planktonic species, while the second pulse, associated...... with the Normalograptus persculptus Zone, was less selective. Glacially induced cooling and oxygenation are two of many suggested kill mechanisms for the end-Ordovician extinction, but a general consensus is lacking. We have used geochemical redox indicators, such as iron speciation, molybdenum concentrations, pyrite...... framboid size distribution and sulfur isotopes to analyze the geochemistry in three key Hirnantian sections. These indicators reveal that reducing conditions were occasionally present at all three sites before the first pulse of the end-Ordovician extinction, and that these conditions expanded towards...

  8. Organic geochemistry of mid-continent Ordovician oils

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, S.E.

    1985-01-01

    Early Paleozoic oils retain the biochemical imprint of oceanic life prior to evolution of land plants and vertebrates. Thus, these oils have geochemical features which make them unique with respect to younger oils, but also share some common properties with the latter. Characteristic mid-continent Ordovician oil features include predominance of n-C/sub 14/ to n-C/sub 19/ over n-C/sub 20/+ alkanes in the C/sub 15/+ saturate hydrocarbon fraction, low amounts of isoprenoids and abundant C/sub 27/ and C/sub 29/ diasteranes relative to normal steranes. Properties common to both Ordovician and younger oils are: nearly equal amounts of C/sub 15/+ n-alkanes, cycloalkanes, and aromatics and pristane/phytane ratios of 0.7 to 1.6. Collectively, these Ordovician oils have a relatively negative stable carbon isotopic composition but are not unique with respect to other marine oils. Although terpane distributions are generally similar to geologically-younger oils, the Ordovician oils contain significant amounts of C/sub 19/, C/sub 20/, and C/sub 21/ tricyclic diterpanes relative to the C/sub 23/ homolog as well as large contributions by C/sub 31/+ pentacyclic triterpanes. Presence of long-chained n-alkanes, C/sub 29/ steranes, and C/sub 24/ tetracyclic terpanes, which are generally accepted as input from land plants in, e.g., Tertiary deposits, are also present in Ordovician oils. The characteristics listed above describe oils from the Williston and Michigan basins as well as Ordovician oils from Kansas and Oklahoma.

  9. Middle-Upper Ordovician (Darriwilian-Early Katian) Positive Carbon Isotope Excursions in the Northern Tarim Basin, Northwest China:Implications for Stratigraphic Correlation and Paleoclimate

    Institute of Scientific and Technical Information of China (English)

    Cunge Liu; Guorong Li; Dawei Wang; Yongli Liu; Mingxia Luo; Xiaoming Shao

    2016-01-01

    ABSTRACT:Three positive carbon isotope excursions are reported from Middle–Upper Ordovician in Tahe oil-gas field, northern Tarim Basin. Based on conodont biostratigraphy, the Middle Darriwilian Isotope Carbon Excursion (MDICE) and the Guttenberg Carbon Isotope Excursion (GICE) are identified from Darriwilian to Early Katian by the aid of whole-rock carbon isotope data from two well cores. Positive excursion within conodont Pygodus anserinus zone is developed in Early Sandbian, and the fluctuation range is no less than MDICE. Because the range of this excursion in the generalized global carbon isotope curve is short, previous studies paid little attention to it, and named Early Sandbian Isotope Carbon Excursion (ESICE) in this paper. Furthermore, these positive excursions are not directly related to sea level fluctuations and the MDICE and GICE identified in northern Tarim can be globally correlated to that in southern China, North America, South America, and Europe. The Saergan Fm. source rocks of Middle-Upper Ordovician in Kalpin Dawangou outcrop are in accord with the geologic time of MDICE and ESICE, and GICE have strong ties to the source rock of Lianglitag Fm. in basin. Abundant organic carbon burial is an important factor in genesis of positive isotope carbon excursions. Positive oxygen isotope excursion, conodont fauna turnover, decreased conodont total diversity, and the change of sedimentary facies indicated that dramatic changes of paleoceanographic environment of Early-Middle Ordovician in Tarim Basin started from the end of Darriwillian, and an obvious icehouse climate of Late Ordovician occurred in ESICE.

  10. New zircon ages on the Cambrian-Ordovician volcanism of the Southern Gemericum basement (Western Carpathians, Slovakia): SHRIMP dating, geochemistry and provenance

    Science.gov (United States)

    Vozárová, Anna; Rodionov, Nickolay; Šarinová, Katarína; Presnyakov, Sergey

    2017-09-01

    The Southern Gemericum basement in the Inner Western Carpathians, composed of low-grade volcano-sedimentary rock complexes, constitutes a record of the polyphase Cambrian-Ordovician continental volcanic arc volcanism. These metavolcanic rocks are characterized by the enrichment in K, Rb, Ba, Th and Ce and Sm relative to Ta, Nb, Hf, Zr, Y and Yb that are the characteristic features for volcanic arc magmatites. The new SHRIMP U-Pb zircon data and compilation of previously published and re-evaluated zircon ages, contribute to a new constrain of the timing of the Cambrian-Ordovician volcanism that occurred between 496 and 447 Ma. The following peaks of the volcanic activity of the Southern Gemericum basement have been recognized: (a) mid-late Furongian at 492 Ma; (b) Tremadocian at 481 Ma; (c) Darriwilian at 464 Ma prolonged to 453 Ma within the early Upper Ordovician. The metavolcanic rocks are characterized by a high zircon inheritance, composed of Ediacaran (650-550 Ma), Tonian-Stenian (1.1-0.9 Ma), and, to a lesser extent, Mesoproterozoic (1.3 Ga), Paleoproterozoic (1.9 Ga) and Archaean assemblages (2.6 Ga). Based on the acquired zircon populations, it could be deduced that Cambrian-Ordovician arc crust was generated by a partial melting of Ediacaran basement in the subduction-related setting, into which old crustal fragments were incorporated. The ascertained zircon inheritances with Meso-, Paleoproterozoic and Archaean cores indicate the similarities with the Saharan Metacraton provenance.

  11. Hydrogeology of the Cambrian-Ordovician aquifer system in the northern Midwest: B in Regional aquifer-system analysis

    Science.gov (United States)

    Young, H.L.; Siegel, D.I.

    1992-01-01

    The Cambrian-Ordovician aquifer system contains the most extensive and continuous aquifers in the northern Midwest of the United States. It is the source of water for many municipalities, industries, and rural water users. Since the beginning of ground-water development from the aquifer system in the late 1800's, hydraulic heads have declined hundreds of feet in the heavily pumped Chicago-Milwaukee area and somewhat less in other metropolitan areas. The U.S. Geological Survey has completed a regional assessment of this aquifer system within a 161,000-square-mile area encompassing northern Illinois, northwestern Indiana, Iowa, southeastern Minnesota, northern Missouri, and Wisconsin.

  12. Discovery of the messaoudensis–trifidum acritarch assemblage (upper Tremadocian–lower Floian, Lower Ordovician in the subsurface of Morocco

    Directory of Open Access Journals (Sweden)

    Hendrik Nowak

    2015-02-01

    Full Text Available The upper Tremadocian to lower Floian messaoudensis–trifidum acritarch assemblage was first described from the Skiddaw Group of England and subsequently from several localities on the Gondwanan margin that were positioned in high southern latitudes during the Early Ordovician. It is here reported for the first time from North Africa, from the Fezouata formations (Tremadocian to Floian in the AZ-1 borehole, southeastern Morocco. The assemblage is comparable with that from the Skiddaw Group, with Cymatiogalea deunffii, C. messaoudensis, C. velifera, Caldariola glabra glabra, Stelliferidium trifidum and Veryhachium lairdii s.l. The Moroccan assemblage indicates a late Tremadocian age.

  13. Asteroid breakup linked to the Great Ordovician Biodiversification Event

    Science.gov (United States)

    Schmitz, Birger; Harper, David A. T.; Peucker-Ehrenbrink, Bernhard; Stouge, Svend; Alwmark, Carl; Cronholm, Anders; Bergström, Stig M.; Tassinari, Mario; Xiaofeng, Wang

    2008-01-01

    The rise and diversification of shelled invertebrate life in the early Phanerozoic eon occurred in two major stages. During the first stage (termed as the Cambrian explosion), a large number of new phyla appeared over a short time interval ~540Myrago. Biodiversity at the family, genus and species level, however, remained low until the second stage marked by the Great Ordovician Biodiversification Event in the Middle Ordovician period. Although this event represents the most intense phase of species radiation during the Palaeozoic era and led to irreversible changes in the biological make-up of Earth's seafloors, the causes of this event remain elusive. Here, we show that the onset of the major phase of biodiversification ~470Myrago coincides with the disruption in the asteroid belt of the L-chondrite parent body-the largest documented asteroid breakup event during the past few billion years. The precise coincidence between these two events is established by bed-by-bed records of extraterrestrial chromite, osmium isotopes and invertebrate fossils in Middle Ordovician strata in Baltoscandia and China. We argue that frequent impacts on Earth of kilometre-sized asteroids-supported by abundant Middle Ordovician fossil meteorites and impact craters-accelerated the biodiversification process.

  14. Early-Mid Ordovician brachiopod diversification in South China

    Institute of Scientific and Technical Information of China (English)

    ZHAN Renbin; RONG Jiayu; CHENG Jinhui; CHEN Pengfei

    2005-01-01

    Affected by paleogeographic position, paleoclimatic condition and depositional environments, the increase of the Early-Mid Ordovician brachiopod diversity of South China commenced at the beginning of the Ordovician (early Tremadoc), accelerated from the Tetragraptus approximatus Biozone (base of Arenig), and reached its first acme in the Didymograptus eobifidus Biozone (mid early Arenig) when the number of brachiopod genera was over 7 times as great as that at the start of the Ordovician. This was the first radiation in the history of brachiopod macroevolution in South China, which occurred nearly 5 graptolitic biozones earlier than the global trend of the great Ordovician biodiversification (in the lower part of the Undulograptus austrodentatus Biozone). It is also characterized by (1) the origination or first occurrences of some major groups, such as the punctate dalmanelloids and the pseudopunctate strophomenoids including Plectambonitoidea (cardinal process simple or absent) and Strophomenoidea (cardinal process bilobed) in South China; (2) niche expansion, particularly in the first occupation of deeper water benthic regimes by the Euorthisina-Nocturnellia Association developed at Houping, Chengkou, northern Chongqing; and (3) the differentiation of brachiopod faunas under different environmental conditions. The gradual and increasing separation from Gondwana may have been one of the factors responsible for the radiation in South China.

  15. Ordovician palynology: balance and future prospects at the beginning of the third millennium.

    Science.gov (United States)

    Servais, T; Paris, F

    2000-12-01

    Ordovician palynologic studies started in the 1930s when Eisenack first described Palaeozoic "hystrichospheres" (later named acritarchs), and defined the chitinozoans and melanosclerites. During the ensuing two decades, Ordovician palynologic investigations were mostly descriptive. It was the rise of the oil industry in the 1950s and 1960s, which accelerated palynologic research, particularly with the recognition that acritarchs and chitinozoans were biostratigraphically important groups for Ordovician stratigraphy. Today, more than 700 publications deal with Ordovician acritarchs, and about 400 papers concern Ordovician chitinozoans. In addition to these two palynomorph groups, other less important organic-walled microorganisms have been studied. These include plant remains (spores, cuticles), scolecodonts and such enigmatic groups as the melanosclerites and the mazuelloids. This paper summarises the research on Ordovician palynomorphs during the 20th century and looks ahead to the types of research that may be important and most fruitful for Ordovician palynology at the beginning of the new millenium. Particular attention is paid to the C.I.M.P./I.G.C.P. no. 410 joint meeting "Ordovician Palynology and Palaeobotany," held in Prague during the 8th International Symposium on the Ordovician System. A brief account is given concerning the global Ordovician chronostratigraphy and the correlation of the main regional series and stages.

  16. A sulfidic driver for the end-Ordovician mass extinction

    DEFF Research Database (Denmark)

    Hammarlund, Emma U.; Dahl, Tais Wittchen; Harper, David A.T.

    2012-01-01

    with the Normalograptus persculptus Zone, was less selective. Glacially induced cooling and oxygenation are two of many suggested kill mechanisms for the end-Ordovician extinction, but a general consensus is lacking. We have used geochemical redox indicators, such as iron speciation, molybdenum concentrations, pyrite...... to an increase in pyrite burial during the early Hirnantian. The S-isotope excursion coincides with a major positive carbon isotope excursion indicating elevated rates of organic carbon burial as well. We argue that euxinic conditions prevailed and intensified in the early Hirnantian oceans...... shelves. In our model, the expansion of euxinic conditions during the N. extraordinarius Zone was generated by a reorganization of nutrient cycling during sea level fall, and we argue, overall, that these dynamics in ocean chemistry played an important role for the end-Ordovician mass extinction. During...

  17. Inferred paleotectonic settings and paleogeography at 500-450 Ma based on geochemical evaluation of Ordovician volcanics and gabbros of the Upper Allochthon, Mid Norway

    Science.gov (United States)

    Hollocher, K.; Roberts, D.; Robinson, P.; Walsh, E.

    2012-04-01

    Evaluation of major- and trace-element analyses of Ordovician volcanics and gabbros from the Støren Nappe of the Upper Allochthon, Mid Norway, including 87 new analyses, covers the Late Cambrian-earliest Ordovician ophiolite complexes and overlying Ordovician volcanics. The older rocks have mainly MORB-like compositions likely formed in a back-arc basin, plus less abundant oceanic-arc basalts and andesites. Compositions characteristic of fore-arc environments are absent. The Upper Allochthon has three elements: A) The Gula Nappe of probable Cambrian and Tremadocian, epicontinental sedimentary rocks, B) The Støren and Meråker nappes with their basal suprasubduction-zone ophiolitic volcanics and intrusions plus younger Ordovician successions, C) In northwestern parts of the Støren Nappe, a complex of predominantly calc-alkaline arc intrusive rocks 482 to 441 Ma. The structural and stratigraphic history indicates obduction of ophiolites occurred at 480-475 Ma soon after formation, followed by uplift, erosion, and deposition of conglomerates incorporating ophiolite debris. The overlying sequence includes shelly Toquima-Table Head faunas of Laurentian affinity and younger strata into Upper Ordovician. Field relations suggest that the ophiolites were obducted onto rocks of the Gula Complex. A Tremadocian, graptolite-bearing black shale/phyllite in the eastern part of the Gula has close geochemical affinities with the reducing V- and U-enriched Alum shale of the Baltoscandian margin, black shales in the lower Köli nappes of the Upper Allochthon in Sweden, and similar shales in the Gander and Avalon zones of Maritime Canada. Such shales originated in high-latitude (40-50° south) cool-water environments, as existed in Late Cambrian-earliest Ordovician Baltica, Avalonia, and Ganderia, and have not been recorded in equatorial paleolatitudes, such as the earliest Ordovician margin of Laurentia. Our paleotectonic account for these features is in three time slices: 1) A

  18. Echinoderms from Middle and Upper Ordovician rocks of Kentucky

    Science.gov (United States)

    Parsley, R.L.

    1981-01-01

    The Middle and Upper Ordovician limestones of Kentucky, especially the Lexington Limestone, have yielded a diverse silicified echinoderm fauna, including: Stylophora-Enoploura cf. E. punctata; Paracrinoidea-A mygdalocystites; Crinoidea, Inadunata-Hybocrir/us tumidus, Hybocystites problem,aticus, Carabocrinus sp., Cupulocrinus sp., Heterocrinus sp.; Cyclocystoidea-Cyclocystoides sp. A rhombiferan cystoid, A mecystis laevis, from the Edinburg Formation, Virginia, is also discussed. No new taxa are introduced.

  19. Glacial Ordovician new evidence in the Pakhuis Formation, South Africa : sedimentological investigation and palaeo-environnemental reconstruction

    Science.gov (United States)

    Portier, E.; Buoncristiani, Jf.; Deronzier, Jf.

    2009-04-01

    During the Late Ordovician (Hirnantian) an ice sheet covered a great part of the Gondwana. In Africa, several studies present the stratigraphy and the complexity of these glacial records. The different glacial landsystems correspond to several glacial cycles, related to rapid ice front oscillations and are grouped into two major ice-sheet advances, separated by a major ice sheet recession. The study was performed on three well outcropping Late Ordovician sections in South Africa. The Ordovician IV is described as the Pakhuis Rm, and is divided into three different lithological members (known as Sneekop, Oskop and Sternbras Mb) that could be related to two major glacial cycles. In the first cycle (pool the two first Mb), facies association indicate continental environment, with : massive sandy tillites with facetted and striated erratics, subaerial outwash plain to glaciolacustrine cross bedded sands and laminated silts. Near Clanwilliam, the outcrops exhibit a high lateral variability in facies and thickness, ranging from a few meters to several tens of meters. The second cycle is dominated by clear marine sedimentation and may be interpreted as a transgressive sequence, quite different from what occurred in North Gondwana. Typical facies define shoreface environment, and periglacial evidence such as dropstones at base are encountered, passing progressively to a clear offshore environment at top of the series, likely Silurian aged, and known as Cederberg fm. Two glacial pavements were also described. The most spectacular one was firstly described by Visser et al. 1974 and should be interpreted as an intra-formational glacial pavement, with striae indicating a flow from East to West. This pavement is overlying a newly discovered glacial floor which exhibits grooves, crescents marks, en echelon fractures, with the same E-W general orientation, and shaped as ‘roches moutonnées', which are typical evidences of glacial erosion on indurated substratum. Reconstructing

  20. Anatomy of the middle ordovician sevier shale basin, eastern Tennessee

    Science.gov (United States)

    Shanmugam, Ganapathy; Walker, Kenneth R.

    1983-04-01

    The Sevier Shale basin in eastern Tennessee comprises one of the thickest clastic sequences (nearly 2500 m) of Middle Ordovician age in North America. The lower one-half of the sequence is composed of Lenoir, Whitesburg, Blockhouse and Sevier Formations, in ascending order. The sequence ranges in age from Whiterockian to lower Wilderness in North American stages. The Middle Ordovician sequence exhibits tidal flat (Mosheim Member of Lenoir Fm.), subtidal (main body of Lenoir Fm.), slope (Whitesburg Fm.), anoxic basin (Blockhouse Fm), turbidite and contourite (Sevier Fm.) facies. The Sevier basin evolved in five stages: First, a widespread marine transgression initiated carbonate-shelf deposition in the study area. Second, a major tectonic downwarping event caused the stable shelf to break and subside rapidly at a rate of 60-65 cm 1000 yrs -1, and areas of shelf facies became areas of slope and basin facies. Third, global transgressions maintained the deep anoxic conditions for nearly 10 Ma. Fourth, turbidites began to fill the basin from a westward-prograding submarine fan system. Fifth, contour currents reworked the turbidites and progressively ventilated the Sevier basin. The basin-filling process terminated with shallow-water/subaerial clastics at the end of Middle Ordovician.

  1. Conodont Biostratigraphy of the Middle Cambrian through Lowermost Ordovician in Hunan, South China

    Institute of Scientific and Technical Information of China (English)

    DONG Xiping; John E. REPETSKI; Stig M. BERGSTR(O)M

    2004-01-01

    Since 1985, samples with a total weight of more than 14,000 kg, mainly from three key sections in western and northwestern Hunan, South China, have been processed for conodonts. In strata older than the late Late Cambrian paraconodonts have proved useful for stratigraphic subdivision and correlation. Thirteen conodont zones are proposed in the Middle Cambrian through lowermost Ordovician. The correlation between these zones and those of North China, western U.S.A., western Newfoundland, Canada, and Iran is discussed. In ascending order, these 13 zones are as follows: The Gapparodus bisulcatus-Westergaardodina brevidens Zone, Shandongodus priscus-Hunanognathus tricuspidatus Zone,Westergaardodina quadrata Zone, Westergaardodina matsushitai-W. grandidens Zone, Westergaardodina lui-W. ani Zone,Westergaardodina cf. calix-Prooneotodus rotundatus Zone, Proconodontus tenuiserratus Zone, Proconodontus Zone,Eoconodontus Zone, Cordylodus proavus Zone, Cordylodus intermedius Zone, Cordylodus lindstromi Zone, and Cordylodus angulatus Zone (lower part). The Westergaardodina lui-W. ani and Westergaardodina cf. calix-Prooneotodus rotundatus Zones replace the Westergaardodina proligula and Westergaardodina cf. behrae-Prooneotodus rotundatus Zones, respectively, in the lowermost Upper Cambrian. Two new species (Westergaardodina lui and Westergaardodina ani)and one conditionally identified species (Westergaardodina cf. calix) are described.

  2. Large-scale Tazhong Ordovician Reef-fiat Oil-Gas Field in the Tarim Basin of China

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xinyuan; WANG Zhaoming; YANG Haijun; ZHANG Lijuan; HAN Jianfa; WANG Zhenyu

    2009-01-01

    The Tazhong reef-flat oil-gas field is the first large-scale Ordovician organic reef type oil-gas field found in China.Its organic reefs were developed in the early Late Ordovician Lianglitag Formation, and are the first large reefs of the coral-stromatoporoid hermatypic community found in China.The organic reefs and platform-margin grain banks constitute a reef-fiat complex, mainly consisting of biolithites and grainstones.The biolithites can be classified into the framestone, bafflestone.bindstone etc.The main body of the complex lies around the wells from Tazhong-24 to Tazhong-82, trending northwest, with the thickness from 100 to 300 m, length about 220 km and width 5-10 km.It is a reef-flat lithologic hydrocarbon reservoir, with a very complex hydrocarbon distribution:being a gas condensate reservoir as a whole with local oil reservoirs.The hydrocarbon distribution is controlled by the reef complex.generally located in the upper 100-200 m part of the complex,and largely in a banded shape along the complex.On the profile,the reservoir shows a stratified feature.with an altitude difierence of almost 2200 m from southeast to northwest.The petroleum accumulation is controlled by karst reservoir beds and the northeast strike-slip fault belt. The total geologic reserves had reached 297.667 Mt by 2007.

  3. Geodynamic setting and geochemical signatures of Cambrian?Ordovician rift-related igneous rocks (Ossa-Morena Zone, SW Iberia)

    Science.gov (United States)

    Sánchez-García, T.; Bellido, F.; Quesada, C.

    2003-04-01

    An important rifting event, accompanied by massive igneous activity, is recorded in the Ossa-Morena Zone of the SW Iberian Massif (European Variscan Orogen). It likely culminated in the formation of a new oceanic basin (Rheic ocean?), remnants of which appear presently accreted at the southern margin of the Ossa-Morena Zone. Rifting propagated diachronously across the zone from the Early Cambrian to the Late Ordovician, but by Early Ordovician time, the existence of a significant tract of new ocean is evidenced by a breakup unconformity. Although early stages of rifting were not accompanied by mantle-derived igneous activity, a pronounced increase of the geothermal gradient is indicated by partial melting of metasedimentary protoliths in the upper and middle crust, and by coeval core-complex formation. Geochemistry of the main volume of igneous rocks, emplaced some million years later during more mature stages of rifting, suggests an origin in a variably enriched asthenospheric source, similar to that of many OIB, from which subsequent petrogenetic processes produced a wide range of compositions, from basalt to rhyolite. A tectonic model involving collision with, and subsequent overriding of, a MOR is proposed to account for the overall evolution, a present-day analogue for which lies in the overriding of the East Pacific Rise by North America and the rifting of Baja California.

  4. Ordovician Cephalopod Biofacies of South China and Its Provincialization

    Institute of Scientific and Technical Information of China (English)

    Xiao Chuantao; Chen Zhiyong; Liu Li; He Youbin

    2006-01-01

    The research on biofacies and its provincialization is of important significance not only for the increasing of precision of stratigraphic subdivision and correlation in South China, the reconstruction of ancient environment and paleogeography and even the guiding of oil and gas exploration, but also for the study of paleobiogeogrphy and sea level changes of southern China in Ordovician. On the basis of the studies of the ecological characteristics of Ordovician cephalopods from South China, eighteen cephalopod biofacies are recognized and described:(1)Open platform Proterocameroceras biofacies;(2) Restricted platform Pseudoectenolites-Xiadongoceras biofacies;(3)Open platform Retroclitend oceras Pararetroclitendoceras biofacies;(4) Open platform Pronajaceras-Mamagouceras biofacies; (5) Shelf slope-basin Cyclostomiceras biofacies; (6) Open platform Cameroceras-Cyrtovaginoceras biofacies;(7) Open platform Coreanoceras-Manchuroceras biofacies; (8) Shelf slope-basin KaipingocerasKyminoceras biofacies; (9) Inner shelf Bathmoceras-Protocycloceras biofacies; (10) Middle shelf Dideroceras-Ancistroceras biofacies; ( 11 ) Deep-water shelf Lituites-Cyclolituites biofacies; (12) Stagnant basin Lituites-Trilacinoceras biofacies; (13) Deep-water basin Paraendoceras-Sactorthoceras biofacies; (14) Deep-water shelf Sinoceras-Michelinoceras-Disoceras biofacies; (15) Deep-water shelf Beloitoceras-Jiangshanoceras biofacies; (16) Deep-water shelf-basin Eurasiaticoceras biofacies; (17)Shelf-slope Jiangxiceras-Yushanoceras biofacies; (18) Deep-water basin Michelinoceras biofacies. The cephalopods of these biofacies, their ecological characteristics, and living conditions are elucidated in this article. The association law of cephalopod biofacies in time and space shows that there were three cephalopod biofacies provinces in South China during the Ordovician, I.e. , Yangtze biofacies province, East Guizhou (贵州)-West Hunan (湖南) biofacies province (mixed-type biofacies province

  5. Ordovician ash geochemistry and the establishment of land plants

    Directory of Open Access Journals (Sweden)

    Parnell John

    2012-08-01

    Full Text Available Abstract The colonization of the terrestrial environment by land plants transformed the planetary surface and its biota, and shifted the balance of Earth’s biomass from the subsurface towards the surface. However there was a long delay between the formation of palaeosols (soils on the land surface and the key stage of plant colonization. The record of palaeosols, and their colonization by fungi and lichens extends well back into the Precambrian. While these early soils provided a potential substrate, they were generally leached of nutrients as part of the weathering process. In contrast, volcanic ash falls provide a geochemically favourable substrate that is both nutrient-rich and has high water retention, making them good hosts to land plants. An anomalously extensive system of volcanic arcs generated unprecedented volumes of lava and volcanic ash (tuff during the Ordovician. The earliest, mid-Ordovician, records of plant spores coincide with these widespread volcanic deposits, suggesting the possibility of a genetic relationship. The ash constituted a global environment of nutrient-laden, water-saturated soil that could be exploited to maximum advantage by the evolving anchoring systems of land plants. The rapid and pervasive inoculation of modern volcanic ash by plant spores, and symbiotic nitrogen-fixing fungi, suggests that the Ordovician ash must have received a substantial load of the earliest spores and their chemistry favoured plant development. In particular, high phosphorus levels in ash were favourable to plant growth. This may have allowed photosynthesizers to diversify and enlarge, and transform the surface of the planet.

  6. Disentangling the record of diagenesis, local redox conditions, and global seawater chemistry during the latest Ordovician glaciation

    Science.gov (United States)

    Ahm, Anne-Sofie C.; Bjerrum, Christian J.; Hammarlund, Emma U.

    2017-02-01

    The Late Ordovician stratigraphic record integrates glacio-eustatic processes, water-column redox conditions and carbon cycle dynamics. This complex stratigraphic record, however, is dominated by deposits from epeiric seas that are susceptible to local physical and chemical processes decoupled from the open ocean. This study contributes a unique deep water basinal perspective to the Late Ordovician (Hirnantian) glacial record and the perturbations in seawater chemistry that may have contributed to the Hirnantian mass extinction event. We analyze recently drilled cores and outcrop samples from the upper Vinini Formation in central Nevada and report combined trace- and major element geochemistry, Fe speciation (FePy /FeHR and FeHR /FeT), and stable isotope chemostratigraphy (δ13COrg and δ34SPy). Measurements of paired samples from outcrop and core reveal that reactive Fe is preserved mainly as pyrite in core samples, while outcrop samples have been significantly altered as pyrite has been oxidized and remobilized by modern weathering processes. Fe speciation in the more pristine core samples indicates persistent deep water anoxia, at least locally through the Late Ordovician, in contrast to the prevailing interpretation of increased Hirnantian water column oxygenation in shallower environments. Deep water redox conditions were likely decoupled from shallower environments by a basinal shift in organic matter export driven by decreasing rates of organic matter degradation and decreasing shelf areas. The variable magnitude in the record of the Hirnantian carbon isotope excursion may be explained by this increased storage of isotopically light carbon in the deep ocean which, in combination with increased glacio-eustatic restriction, would strengthen lateral- and vertical gradients in seawater chemistry. We adopt multivariate statistical methods to deconstruct the spatial and temporal re-organization of seawater chemistry during the Hirnantian glaciation and attempt to

  7. The Middle Ordovician Knox unconformity in the Black Warrior Basin

    Science.gov (United States)

    Dwyer, Gary S.; Repetski, John E.

    2012-01-01

    Analysis of well core and cuttings from the Black Warrior Basin in Mississippi reveals the presence of a Middle Ordovician (Whiterockian) erosional unconformity interpreted to be equivalent to the well-known Knox-Beekmantown unconformity in eastern North America. The unconformity occurs at the top of a peritidal dolostone unit known informally as the upper dolostone, whose stratigraphic placement has been the subject of a long-standing controversy. The unconformity, which represents the Sauk-Tippecanoe megasequence boundary on the North American craton, was previously thought to be short-lived or altogether absent in the Black Warrior Basin.

  8. Ordovician chitinozoan biozonation of the Brabant Massif, Belgium.

    Science.gov (United States)

    Samuelsson, J; Verniers, J

    2000-12-01

    Chitinozoans from seven Ordovician units (Abbaye de Villers, Tribotte, Rigenée, Ittre, Bornival, and Brutia formations and a new unnamed unit, here provisionally called the Asquempont unit) belonging to the mainly concealed Brabant Massif, Belgium are described herein. Fifty-six samples were taken from rocks cropping out at the south-eastern rim of the massif in the Orneau, Dyle-Thyle and Senne-Sennette valleys. Microfossil preservation is moderate to poor, and the chitinozoans occur in low numbers. Taxonomically, the recovered chitinozoans are distributed into 29 taxa, some placed under open nomenclature. Together with earlier published graptolite and acritarch data, the analysis of the chitinozoan assemblages resulted in an improved chronostratigraphy of the investigated formations. We propose a local chitinozoan biozonation with 11 zones for the Brabant Massif. The oldest investigated units yielded chitinozoans typical for North Gondwana, and younger units (starting in the middle Caradoc), yielded some taxa also common in Baltica. As the Brabant Massif formed part of the microcontinent Avalonia, the chitinozoan assemblages recovered from the massif support the inferred drifting of Avalonia from high latitudes towards middle latitudes in the Ordovician as was suggested earlier.

  9. Fontes de resistência em tomateiro aos begomovírus bissegmentados Tomato yellow spot virus e Tomato severe rugose virus Sources of resistance in tomato to bipartite begomoviruses Tomato yellow spot virus and Tomato severe rugose virus

    Directory of Open Access Journals (Sweden)

    Francisco D Hurtado

    2012-12-01

    Full Text Available Os begomovírus causam doenças de grande importância econômica em diversas culturas, principalmente em regiões tropicais e subtropicais. Juntamente com outras famílias de vírus, os begomovírus têm causado grande prejuízo para os produtores de tomate in natura e para processamento industrial. O objetivo deste trabalho foi avaliar o comportamento de 11 genótipos resistentes ao Tomato yellow leaf curl virus (TYLCV frente à infecção pelos begomovírus Tomato yellow spot virus (ToYSV e Tomato severe rugose virus (ToSRV em condições de casa-vegetação. A inoculação das plantas foi realizada via biobalística no estádio de duas folhas verdadeiras. A infecção viral confirmou-se pelo desenvolvimento dos sintomas e pela técnica de hibridização dot blot. Selecionaram-se como promissores os genótipos STY2, STY5, STY6 e L7, por não apresentarem sintomas e por terem concentrações virais muito baixas para os dois vírus. O espectro de resistência dos genes Ty-1 e Ty-2 não resultaram efetivos ante as espécies virais empregadas no estudo. As linhagens TY52, H24 e CLN2116B, portadoras destes genes, foram suscetíveis aos vírus ToYSV e ToSRV.Begomoviruses cause diseases of major economic importance in many crops, especially in tropical and subtropical regions. Together with other families of viruses, the begomoviruses cause great damage for producers of fresh and processed tomatoes. The objective of this study was to evaluate the behavior of 11 resistant genotypes to Tomato yellow leaf curl virus (TYLCV when infected by the begomoviruses Tomato severe rugose virus (ToSRV and Tomato yellow spot virus (ToYSV under greenhouse conditions. Tomato plants were inoculated by biobalistic method when displaying two true leaves. Viral infection was confirmed by visual observation of symptoms and by dot blot hybridization. Genotypes STY2, STY5, STY6 and L7 were selected as promising due to the absence of symptoms and very low viral

  10. Reassignment to the Middle Devonian of some rugose corals investigated by LE MAÎTRE (1934) in the Chalonnes Formation from the Southeastern Armorican Massif (France)

    OpenAIRE

    2011-01-01

    Nine taxa of rugose corals collected by LEMAÎTRE (1934) and coming from the Chalonnes Formation of the Southeastern Armorican Massif in France have been revised. They belong to the genera Stringophyllum WEDEKIND, 1922, Sociophyllum BIRENHEIDE, 1962, Acanthophyllum DYBOWSKI, 1873, Beugniesastraea COEN-AUBERT, 1989 and Fasciphyllum SCHLÜTER, 1885. Among this material, Stringophyllum acanthicum (FRECH, 1885), Sociophyllum elongatum (SCHLÜTER, 1881), Acanthophyllum vermiculare (GOLDFUSS, 1826) an...

  11. Ordovician magmatism in the Lévézou massif (French Massif Central): tectonic and geodynamic implications

    Science.gov (United States)

    Lotout, Caroline; Pitra, Pavel; Poujol, Marc; Van Den Driessche, Jean

    2017-03-01

    New U-Pb dating on zircon yielded ca. 470 Ma ages for the granitoids from the Lévézou massif in the southern French Massif Central. These new ages do not support the previous interpretation of these granitoids as syn-tectonic intrusions emplaced during the Late Devonian-Early Carboniferous thrusting. The geochemical and isotopic nature of this magmatism is linked to a major magmatic Ordovician event recorded throughout the European Variscan belt and related to extreme thinning of continental margins during a rifting event or a back-arc extension. The comparable isotopic signatures of these granitoids on each side of the eclogite-bearing leptyno-amphibolitic complex in the Lévézou massif, together with the fact that they were emplaced at the same time, strongly suggest that these granitoids were originally part of a single unit, tectonically duplicated by either isoclinal folding or thrusting during the Variscan tectonics.

  12. End of the chain? Rugosity and fine-scale bathymetry from existing underwater digital imagery using structure-from-motion (SfM) technology

    Science.gov (United States)

    Storlazzi, Curt D.; Dartnell, Peter; Hatcher, Gerald A.; Gibbs, Ann E.

    2016-09-01

    The rugosity or complexity of the seafloor has been shown to be an important ecological parameter for fish, algae, and corals. Historically, rugosity has been measured either using simple and subjective manual methods such as `chain-and-tape' or complicated and expensive geophysical methods. Here, we demonstrate the application of structure-from-motion (SfM) photogrammetry to generate high-resolution, three-dimensional bathymetric models of a fringing reef from existing underwater video collected to characterize the seafloor. SfM techniques are capable of achieving spatial resolution that can be orders of magnitude greater than large-scale lidar and sonar mapping of coral reef ecosystems. The resulting data provide finer-scale measurements of bathymetry and rugosity that are more applicable to ecological studies of coral reefs than provided by the more expensive and time-consuming geophysical methods. Utilizing SfM techniques for characterizing the benthic habitat proved to be more effective and quantitatively powerful than conventional methods and thus might portend the end of the `chain-and-tape' method for measuring benthic complexity.

  13. End of the chain? Rugosity and fine-scale bathymetry from existing underwater digital imagery using structure-from-motion (SfM) technology

    Science.gov (United States)

    Storlazzi, Curt; Dartnell, Peter; Hatcher, Gerry; Gibbs, Ann E.

    2016-01-01

    The rugosity or complexity of the seafloor has been shown to be an important ecological parameter for fish, algae, and corals. Historically, rugosity has been measured either using simple and subjective manual methods such as ‘chain-and-tape’ or complicated and expensive geophysical methods. Here, we demonstrate the application of structure-from-motion (SfM) photogrammetry to generate high-resolution, three-dimensional bathymetric models of a fringing reef from existing underwater video collected to characterize the seafloor. SfM techniques are capable of achieving spatial resolution that can be orders of magnitude greater than large-scale lidar and sonar mapping of coral reef ecosystems. The resulting data provide finer-scale measurements of bathymetry and rugosity that are more applicable to ecological studies of coral reefs than provided by the more expensive and time-consuming geophysical methods. Utilizing SfM techniques for characterizing the benthic habitat proved to be more effective and quantitatively powerful than conventional methods and thus might portend the end of the ‘chain-and-tape’ method for measuring benthic complexity.

  14. Advances in the Ordovician graptolite biostratigraphy of the St Petersburg area, Russia

    Directory of Open Access Journals (Sweden)

    Suyarkova, Anna A.

    2009-03-01

    Full Text Available The Ordovician shallow-water shelf deposits rich in benthic fauna are exposed along the Russian part of the Baltic–Ladoga Klint. Graptolites occur only at some stratigraphic levels, being comparatively numerous in marls and clays and very rare in carbonate layers. Since the 19th century graptolites have been collected from exposures of the Pakerort, Hunneberg, Billingen, and Volkhov regional stages (Tremadocian–Dapingian, while in the Uhaku–Idavere stratigraphic interval (Darriwilian–lower Sandbian rare graptolites have been found in boreholes. Up to now, only some collections have been systematically studied. On the basis of new graptolite finds, recently the Pterograptus elegans Biozone was established in the upper Aseri Stage and the Nemagraptus gracilis Biozone in the lower Kukruse Stage. Detailed sampling of the Shundorovo Formation (upper Idavere Stage resulted in the discovery of numerous diplograptids at five stratigraphic levels, in association with various dendroids. These diplograptids were provisionally assigned to ?Archiclimacograptus antiquus lineatus Elles & Wood. A systematic description of the late Darriwilian and early Sandbian diplograptids is under preparation.

  15. Volcanism and Tectonic Evolution in the North Qilian Mountains during Ordovician Period

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The Ordovician marine volcanic rocks in the north Qilian mountains are discussed in this paper. According to geology, petrotectonic assemblage and geochemistry, a new model about plate tectonic evolution of the north Qilian mountains is set up. The Ordovician marine volcanic rocks in the north Qilian mountains which characterized by the geological features of tectonic melange of continent to continent collision underwent complicated tectonic movement, and can be classified into three main kinds of petrotectonic assemblages. During Ordovician period, north Qilian area was a polyisland ocean which consisted of three ocean basins separated by the middle microcontinental blocks.

  16. Rugosity and hardness determination in obsidianus lapis for the design of an Yb3+-doped fiber laser

    Science.gov (United States)

    Alvarez-Chavez, J. A.; Aguilar-Morales, A. I.; Perez-Sanchez, G. G.; Morales-Ramirez, A. J.

    2015-01-01

    Obsidianus lapis is a volcanic rock that has been worked into tools for cutting or weaponry by Teotihuacan people for hundreds of years. Currently, it is used in jewelry or for house decorative items such as elaborated sculptures. From the physico-chemical properties point of view, obsidianus lapis is considered a glass as its composition is 80% silicon dioxide. In México, there are different kinds of obsidianus lapis which are classified according to its colour: rainbow, black, brown, red, silver, golden and snowflake. The traditional grinding process for working with obsidianus lapis includes fixed grinders and sandpaper for the polishing process, where the craftsman grinds the rock manually for obtaining a variety of shapes. Laser processing of natural stones is a relatively new area. We propose the use of an Yb3+-doped fibre laser for cutting and ablating obsidianus lapis into spherical, rectangular and oval shapes. By means of a theoretical analysis of roughness and hardness, which affect the different surfaces and final shapes, and by considering the changes in material temperature during laser interaction, this work will focus on parameter determination such as: laser fluence, incidence angle, laser average power and peak pulse energy, from the proposed Q-switched fibre laser design. Full optical, hardness and rugosity, initial and final characterization will be included in the presentation.

  17. Accretion Rates of Meteorites and Cosmic Dust in the Early Ordovician

    National Research Council Canada - National Science Library

    Birger Schmitz; Bernhard Peucker-Ehrenbrink; Maurits Lindström; Mario Tassinari

    1997-01-01

    ... an interval of the Early Ordovician than at present. Osmium isotope and iridium analyses of whole-rock limestone indicate a coeval enhancement of one order of magnitude in the influx rate of cosmic dust...

  18. Trilobites from the Middle Ordovician Stairway Sandstone, Amadeus Basin, central Australia

    DEFF Research Database (Denmark)

    Jakobsen, Kristian Grube; Nielsen, Arne Thorshøj; Harper, David Alexander Taylor;

    2014-01-01

    During the Middle Ordovician (Darriwilian) sandstones and siltstones were deposited in the epicontinental Larapintine Sea, which covered large parts of central Australia. The Darriwilian Stairway Sandstone has, for the first time, been sampled stratigraphically for macrofossils to track marine be...

  19. Global Stratotype Section and Point for base of the Ordovician System

    Institute of Scientific and Technical Information of China (English)

    R. A. Cooper; G. S. Nowlan; S. H. Williams

    2001-01-01

    @@ The Global Stratotype Section and Point for base of the Ordovician System and base of the lowest Ordovician stage (Tremadocian) is exposed in the coastal platform at Green Point, western Newfoundland, at the 101.8 m level, within Bed 23, in the measured section (Lower Broom Point Member, Green Point Formation), coinciding with the first appearance of the conodont Iapetognathus fluctivagus Nicoll, Miller, Nowlan,Repetski and Ethington, 1999, and 4.8 m below the earliest planktic graptolites.

  20. Late Ordovician (Turinian-Chatfieldian) carbon isotope excursions and their stratigraphic and paleoceanographic significance

    Science.gov (United States)

    Ludvigson, Greg A.; Witzke, B.J.; Gonzalez, Luis A.; Carpenter, S.J.; Schneider, C.L.; Hasiuk, F.

    2004-01-01

    Five positive carbon isotope excursions are reported from Platteville-Decorah strata in the Upper Mississippi Valley. All occur in subtidal carbonate strata, and are recognized in the Mifflin, Grand Detour, Quimbys Mill, Spechts Ferry, and Guttenberg intervals. The positive carbon isotope excursions are developed in a Platteville-Decorah succession in which background ??13C values increase upward from about -2??? at the base to about 0??? Vienna Pee Dee belemnite (VPDB) at the top. A regional north-south ??13C gradient, with lighter values to the north and heavier values to the south is also noted. Peak excursion ??13C values of up to +2.75 are reported from the Quimbys Mill excursion, and up to +2.6 from the Guttenberg excursion, although there are considerable local changes in the magnitudes of these events. The Quimbys Mill, Spechts Ferry, and Guttenberg carbon isotope excursions occur in units that are bounded by submarine disconformities, and completely starve out in deeper, more offshore areas. Closely spaced chemostratigraphic profiles of these sculpted, pyrite-impregnated hardground surfaces show that they are associated with very abrupt centimeter-scale negative ??13C shifts of up to several per mil, possibly resulting from the local diagenetic effects of incursions of euxinic bottom waters during marine flooding events. ?? 2004 Elsevier B.V. All rights reserved.

  1. Lithostratigraphy of Upper Ordovician strata exposed in Kentucky

    Science.gov (United States)

    Weir, Gordon Whitney; Peterson, Warren Lee; Swadley, W.C.

    1984-01-01

    Ordovician formations above the Lexington Limestone crop out in the Blue Grass region of Kentucky and along the Cumberland River and its tributaries. The formations are all conformable and in places intertongue and intergrade. The major Ordovician units above the Lexington Limestone in the Blue Grass region are: The Clays Ferry Formation, the Kope Formation, the Garrard Siltstone, the Fairview Formation, the Calloway Creek Limestone, the Grant Lake Limestone, the Ashlock Formation, the Bull Fork Formation, and the Drakes Formation. The Clays Ferry Formation is made up of subequal amounts of fossiliferous limestone and shale and minor siltstone; the Clays Ferry is as much as 300 ft thick and intertongues with the Lexington Limestone and the Kope Formation. The Kope Formation resembles the partly equivalent Clays Ferry but has a higher shale content (60-80 percent) and thicker layers of shale; the Kope, as much as 275 ft thick, is mostly restricted to the northern part of the State. The Garrard Siltstone, which consists of very calcitic siltstone and minor shale, overlies the Clays Ferry Formation in the southeastern part of the Blue Grass region; the Garrard, as much as 100 ft thick, feathers out into the upper part of the Clays Ferry in southern central and northern east-central Kentucky. The Fairview Formation is characterized by even-bedded limestone interlayered with nearly equal amounts of shale and minor siltstone. The Fairview crops out in the northern part of the Blue Grass region, where it generally overlies the Kope Formation or the Garrard Siltstone; it grades southward into the Calloway Creek Limestone. The Calloway Creek contains more limestone (generally at least 70 percent) and is more irregularly and thinner bedded than the Fairview. The Grant Lake Limestone is composed of nodular-bedded limestone (70-90 percent), interlayered and intermixed with shale; it overlies the Fairview Formation in the northern part of the Blue Grass region and the Calloway

  2. Temporal Distribution of Diagnostic Biofabrics in the Lower and Middle Ordovician in North China:Clues to the Geobiology of the Great Ordovician Biodiversification Event

    Institute of Scientific and Technical Information of China (English)

    LIU Jianbo; ZHAN Renbin

    2009-01-01

    The temporal distribution of the diagnostic biofabrics In the Lower and Middle Ordovician in North China distinctly illustrates that the sedimentary systems on the paleoplate have been changed markedly as consequences of the Great Ordovician Biodiversification Event (GOBE).The pre-GOBE sedimentary systems deposited in Tremadoc display widespread microbialite and flat-pebble conglomerates,and a less extent of bioturbation.Through the transitional period of early Floian,the sedimentary systems in the rest of the Early and Mid-Ordovician change to GOBE type and are characterized by intensive bioturbation and vanishing flat-pebble conIglomerates and subtidal microbial sediments.The irreversible changes in sedimentary systems in North China are Iinked to the GOBE,which conduced the increase in infaunal tiering,the expansion of infaunal ecospace,and the appearance of new burrowers related to the development of the Paleozoic Evolutionary Fauna during the Ordovician biodiversification.Thus,changes in sedimentary systems during the pivotal period of the GOBE were consequences of a steep diversification of benthic faunas rather than the GOBE's environmental background.

  3. Shale gas reservoir characteristics of Ordovician-Silurian formations in the central Yangtze area, China

    Science.gov (United States)

    Shan, Chang'an; Zhang, Tingshan; Wei, Yong; Zhang, Zhao

    2016-07-01

    The characteristics of a shale gas reservoir and the potential of a shale gas resource of Ordovician-Silurian age in the north of the central Yangtze area were determined. Core samples from three wells in the study area were subjected to thin-section examination, scanning electron microscopy, nuclear magnetic resonance testing, X-ray diffraction mineral analysis, total organic carbon (TOC) testing, maturity testing, gas-bearing analysis, and gas component and isothermal adsorption experiments. A favorable segment of the gas shale reservoir was found in both the Wufeng Formation and the lower part of the Longmaxi Formation; these formations were formed from the late Katian to early Rhuddanian. The high-quality shale layers in wells J1, J2, and J3 featured thicknesses of 54.88 m, 48.49 m, and 52.00 m, respectively, and mainly comprised carbonaceous and siliceous shales. Clay and brittle minerals showed average contents of 37.5% and 62.5% (48.9% quartz), respectively. The shale exhibited type II1 kerogens with a vitrinite reflectance ranging from 1.94% to 3.51%. TOC contents of 0.22%-6.05% (average, 2.39%) were also observed. The reservoir spaces mainly included micropores and microfractures and were characterized by low porosity and permeability. Well J3 showed generally high gas contents, i.e., 1.12-3.16 m3/t (average 2.15 m3/t), and its gas was primarily methane. The relatively thick black shale reservoir featured high TOC content, high organic material maturity, high brittle mineral content, high gas content, low porosity, and low permeability. Shale gas adsorption was positively correlated with TOC content and organic maturity, weakly positive correlated with quartz content, and weakly negatively correlated with clay content. Therefore, the Wufeng and Longmaxi formations in the north of the central Yangtze area have a good potential for shale gas exploration.

  4. Shale gas reservoir characteristics of Ordovician-Silurian formations in the central Yangtze area, China

    Science.gov (United States)

    Shan, Chang'an; Zhang, Tingshan; Wei, Yong; Zhang, Zhao

    2017-03-01

    The characteristics of a shale gas reservoir and the potential of a shale gas resource of Ordovician-Silurian age in the north of the central Yangtze area were determined. Core samples from three wells in the study area were subjected to thin-section examination, scanning electron microscopy, nuclear magnetic resonance testing, X-ray diffraction mineral analysis, total organic carbon (TOC) testing, maturity testing, gas-bearing analysis, and gas component and isothermal adsorption experiments. A favorable segment of the gas shale reservoir was found in both the Wufeng Formation and the lower part of the Longmaxi Formation; these formations were formed from the late Katian to early Rhuddanian. The high-quality shale layers in wells J1, J2, and J3 featured thicknesses of 54.88 m, 48.49 m, and 52.00 m, respectively, and mainly comprised carbonaceous and siliceous shales. Clay and brittle minerals showed average contents of 37.5% and 62.5% (48.9% quartz), respectively. The shale exhibited type II1 kerogens with a vitrinite reflectance ranging from 1.94% to 3.51%. TOC contents of 0.22%-6.05% (average, 2.39%) were also observed. The reservoir spaces mainly included micropores and microfractures and were characterized by low porosity and permeability. Well J3 showed generally high gas contents, i.e., 1.12-3.16 m3/t (average 2.15 m3/t), and its gas was primarily methane. The relatively thick black shale reservoir featured high TOC content, high organic material maturity, high brittle mineral content, high gas content, low porosity, and low permeability. Shale gas adsorption was positively correlated with TOC content and organic maturity, weakly positive correlated with quartz content, and weakly negatively correlated with clay content. Therefore, the Wufeng and Longmaxi formations in the north of the central Yangtze area have a good potential for shale gas exploration.

  5. Discovery and its geological significance of the mantle-derived helium in the inclusions of the Ordovician oil-bearing reservoir rocks in the Huanghua depression, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaobao; XU Yongchang; SUN Mingliang; CHENG Keming; LIU Wenhui; LI Xiufen; MA Liyuan

    2004-01-01

    The values of the helium isotopes in the inclusions of the Ordovician reservoir rocks in the Kongxi buried hill belt in the Huanghua depression were first measured and the source of helium and its geological significance were investigated in comparison with those of the helium isotopes in the conclusions in the Ordovician rocks in the Ordos basin and the Tarim basin. The input of the mantle-derived helium into the inclusions in the carbonate reservoir rocks was found from the Konggu 3 well, the Konggu 4 well, and the Konggu 7 well in the Kongxi buried hill belt. The 3He/4He and R/Ra in the conclusions in the Ordovician oil-bearing reservoir rocks in the Konggu 7 well average 2.54×10-6(3) (sample quantity, the same below) and 1.82(3), respectively. The percent of the mantle-derived helium in the inclusions of the reservoir rocks in the Konggu 7 well reaches up to an average of 23.0%(3). The age of the contribution of the mantle-derived helium to the inclusions in the Kongxi buried hill belt is in the Late Triassic or the Early Tertiary. The finding of the mantle-derived helium shows that the interaction of the deep crust with mantle and the activity of deep faults occurred, the terrestrial heat flow value was high, and mantle-derived inorganic gas pools might be formed in the Kongxi buried hill belt. The finding of the mantle-derived helium in the inclusions of oil-bearing reservoir rocks also provides a new way for researching the activity of mantle-derived matter and its associated geological problems.

  6. An acercostracan marrellomorph (Euarthropoda) from the Lower Ordovician of Morocco

    Science.gov (United States)

    Legg, David A.

    2016-04-01

    Enosiaspis hrungnir gen. et sp. nov., a new species of marrellomorph arthropod from the Lower Ordovician (Tremadocian) Fezouata biota of Morocco, is described. This taxon is characterised by the possession of a cordiform dorsal carapace with an anterior notch and a doublure-like structure formed from fused marginal spines, covering the entire body. The head comprises at least five segments which bear an anterior pair of antenna, followed by three pairs of potentially biramous, geniculate appendages. The trunk possesses around 25 pairs of delicate, almost filamentous appendages, which decrease in size posteriorly. Similar features are also found in Xylokorys chledophilia from the Silurian of England, and Vachonisia rogeri from the Devonian of Germany, indicating acercostracan affinities for E. hrungnir. This was tested using a phylogenetic analysis which resolved this taxon as sister taxon to a group composed of the formerly mentioned taxa. The similarities between the ventral spinose carapace doublure of E. hrungnir and the mediolateral spines of marrellid marrellomorphs further support claims that the dorsal shield of acercostracans evolved from the fusion of spinose anlagen, akin to the formation of the carapace of crustaceans.

  7. Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification.

    Science.gov (United States)

    Lindskog, A; Costa, M M; Rasmussen, C M Ø; Connelly, J N; Eriksson, M E

    2017-01-24

    The catastrophic disruption of the L chondrite parent body in the asteroid belt c. 470 Ma initiated a prolonged meteorite bombardment of Earth that started in the Ordovician and continues today. Abundant L chondrite meteorites in Middle Ordovician strata have been interpreted to be the consequence of the asteroid breakup event. Here we report a zircon U-Pb date of 467.50±0.28 Ma from a distinct bed within the meteorite-bearing interval of southern Sweden that, combined with published cosmic-ray exposure ages of co-occurring meteoritic material, provides a precise age for the L chondrite breakup at 468.0±0.3 Ma. The new zircon date requires significant revision of the Ordovician timescale that has implications for the understanding of the astrogeobiologic development during this period. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated.

  8. Resposta à mosca-branca (Bemisia tabaci e ao Tomato severe rugose virus de acessos de Solanum subgênero Leptostemonum Reaction to whitefly (Bemisia tabaci and Tomato severe rugose virus of Solanum subgenus Leptostemonum accessions

    Directory of Open Access Journals (Sweden)

    Miguel Michereff-Filho

    2012-09-01

    Full Text Available A mosca-branca (Bemisia tabaci e a infecção por espécies de Begomovirus são dois graves problemas fitossanitários que afetam a produção e qualidade do tomateiro (Solanum lycopersicum e de outras solanáceas de importância econômica. O presente trabalho foi conduzido sob condições controladas, em casa de vegetação, visando avaliar a resposta ao Tomato severe rugose virus (ToSRV e à mosca-branca (B. tabaci biótipo B de 36 acessos de espécies relacionadas ao gênero Solanum subgênero Leptostemonum (= grupo das solanáceas providas de espinhos. A inoculação de ToSRV foi realizada em mudas (43 dias após o semeio utilizando-se um colônia virulífera de B. tabaci biótipo B. Duas cultivares de tomateiro foram incluídas como testemunhas suscetíveis. A avaliação ao ToSRV foi feita de acordo com uma escala de severidade de sintomas e a presença de infecção sistêmica foi verificada via reação em cadeia da polimerase (PCR com 'primers' universais para espécies de Begomovirus. A maioria dos acessos apresentou uma resposta do tipo resistência ou quase imunidade ao ToSRV, não apresentando sintomas evidentes e nenhum indício de infecção sistêmica ou acumulação viral. Um grupo reduzido de acessos de S. stramonifolium, S. asperolanatum e S. jamaiscense apresentou uma resposta do tipo tolerância, caracterizada por baixa acumulação viral e sintomas suaves. O acesso S. mammosum 'CNPH 035', embora tolerante, foi o único que apresentou sintomas mais evidentes de infecção viral e acumulação de ToSRV. O mesmo grupo de 36 acessos foi avaliado em relação à colonização por B. tabaci em testes de livre escolha. Diferenças significativas foram observadas entre acessos para oviposição e o número de ninfas no quarto instar, indicando a presença de fatores de resistência ao inseto. Dez acessos de S. asperolanatum, S. stramonifolium, S. paniculatum e S. syssimbriifolium se mostraram completamente livres de oviposi

  9. Early Permian extensional shearing of an Ordovician granite: The Saint-Eutrope "C/S-like" orthogneiss (Montagne Noire, French Massif Central)

    Science.gov (United States)

    Pitra, Pavel; Poujol, Marc; Van Den Driessche, Jean; Poilvet, Jean-Charles; Paquette, Jean-Louis

    2012-08-01

    Dating the magmatic events in the Montagne Noire gneiss dome is a key point to arbitrate between the different interpretations of the Late Carboniferous-Early Permian tectonics in this southern part of the Variscan belt. The Saint-Eutrope orthogneiss crops out along the northern flank of the dome. We show that the protolith of this orthogneiss is an Ordovician granite dated at 455 ± 2 Ma (LA-ICP-MS U-Pb dating on zircon). This age is identical to that previously obtained on the augen orthogneiss of the southern flank, strongly suggesting that both orthogneiss occurrences have the same Ordovician protolith. The Saint-Eutrope orthogneiss experienced intense shearing along the Espinouse extensional detachment at ca. 295 Ma (LA-ICP-MS U-Pb-Th on monazite), an age close to that determined previously on mica by the 39Ar-40Ar method and contemporaneous with the emplacement age of the syntectonic Montalet granite farther to the west. This normal sense shearing reworked previous fabrics related to Variscan thrusting that can be still observed in the augen orthogneiss of the southern flank, and is responsible for the spectacular "C/S-like" pattern of the Saint-Eutrope orthogneiss. This work also shows that care is needed when dealing with C/S-type structures, since they can develop not only in syntectonic intrusions, but also in orthogneisses affected by an intense secondary deformation, at decreasing temperature.

  10. Composition and significance of the Katian (Upper Ordovician conodont fauna of the Vaux Limestone (‘Calcaire des Vaux’ in Normandy, France

    Directory of Open Access Journals (Sweden)

    Annalisa Ferretti

    2014-12-01

    Full Text Available Study of new conodont collections from the Vaux Limestone exposed at its classical locality at Saint-Hilaire-la-Gérard in the Sées syncline, the conodont fauna of which was previously described in a preliminary way by Weyant et al. (1977, Un épisode calcaire ashgillien dans l’est du Massif armoricain; incidence sur l’âge des dépôts glacio-marins fini-ordoviciens. Comptes Rendus de l'Académie des Sciences, Paris, 284, Série D, 1147–1149, has provided significant new information about Late Ordovician conodonts from Normandy. A more precise age of this formation has been established based on an unexpectedly abundant conodont fauna of low diversity. Representatives of Amorphognathus, Hamarodus, Sagittodontina, Scabbardella and Eocarniodus are present and the fauna is referable to the middle Katian–lower Hirnantian A. ordovicicus Zone. Our study, the first illustrating Ordovician conodonts from Normandy, shows that the fauna is closely similar to middle Katian faunas from other parts of continental Europe and represents the Sagittodontina robusta–Scabbardella altipes biofacies of the Mediterranean Province.

  11. Palaeomagnetic evidence from the Ordovician and Silurian of northwest Peninsular Malaysia

    Science.gov (United States)

    Haile, N. S.

    1980-06-01

    The Ordovician and Silurian Setul Limestone of the Langkawi Islands, northwest Peninsular Malaysia, has a mean magnetic vector of D = 338°, I = 62° after cleaning and correction for tilt. This is equivalent to a palaeolatitude of 43°, and a palaeomagnetic pole at 46°N, 76°E. The Silurian part of the Setul limestone also shows a similar direction. The Ordovician results are equivalent to a palaeolatitude of 43°, N or S. Recent reconstructions, based on palaeontology, place Indochina and China in the northern hemisphere in the Ordovician; if this is correct, a palaeolatitide of 43° for Langkawi would imply that Malaya-Indochina was the most northerly continental fragment at that time.

  12. Paleoredoc and pyritization of soft-bodied fossils in the Ordovician Frankfort Shale of New York

    DEFF Research Database (Denmark)

    Farrell, Una C.; Briggs, Derek E. G.; Hammarlund, Emma U.

    2013-01-01

    Multiple beds in the Frankfort Shale (Upper Ordovician, New York State), including the original "Beecher's Trilobite Bed," yield fossils with pyritized soft-tissues. A bed-by-bed geochemical and sedimentological analysis was carried out to test previous models of soft-tissue pyritization by inves......Multiple beds in the Frankfort Shale (Upper Ordovician, New York State), including the original "Beecher's Trilobite Bed," yield fossils with pyritized soft-tissues. A bed-by-bed geochemical and sedimentological analysis was carried out to test previous models of soft-tissue pyritization...

  13. Accretion rates of meteorites and cosmic dust in the Early Ordovician.

    Science.gov (United States)

    Schmitz, B; Peucker-Ehrenbrink, B; Lindstrom, M; Tassinari, M

    1997-10-03

    Abundant fossil meteorites in marine, condensed Lower Ordovician limestones from Kinnekulle, Sweden, indicate that accretion rates of meteorites were one to two orders of magnitude higher during an interval of the Early Ordovician than at present. Osmium isotope and iridium analyses of whole-rock limestone indicate a coeval enhancement of one order of magnitude in the influx rate of cosmic dust. Enhanced accretion of cosmic matter may be related to the disruption of the L chondrite parent body around 500 million years ago.

  14. Chief sources of brachiopod recovery from the end Ordovician mass extinction with special references to progenitors

    Institute of Scientific and Technical Information of China (English)

    戎嘉余; 詹仁斌

    1999-01-01

    Survivor, Lazarus and progenitor taxa are sources of biotic recovery following mass extinction. Investigations of the benthic brachiopods through the latest Ordovician mass extinction shows that progenitors developed many evolutionary novelties and successful surviving mechanisms. They are superior to survivors and Lazarus taxa in their ability to adapt to environmental changes. They are the primary source of macroevolution and the ancestors of a number of new taxa. Three kinds of progenitors are recognized based on the Ordovician-Silurian brachiopods from South China: survivor-progenitors, crisis-progenitors and Lazarus-progenitors; the last has the strongest ability to resist adverse environments, and is the most diverse and abundant.

  15. Carbon isotope stratigraphy of an ancient (Ordovician) Bahamian-type carbonate platform: Implications for preservation of global seawater trends

    Science.gov (United States)

    Saltzman, M.; Leslie, S. A.; Edwards, C. T.; Diamond, C. W.; Trigg, C. R.; Sedlacek, A. R.

    2013-12-01

    . Few studies of ancient carbonates have attempted to explicitly compare C-isotope trends in both restricted platform settings and open marine settings (e.g., Immenhauser et al. 2002). We studied a restricted Bahamian-type carbonate platform of Middle-Late Ordovician (Darriwilian-early Sandbian) age included in the St. Paul Group of Maryland, notable for sedimentologic evidence of severe restriction and a general lack of open marine macrofauna. We are able to correlate the C-isotope curve from the St. Paul Group to other sections globally by using a combination of conodont microfossils and measurement of Sr isotopes on conodont apatite. Coeval C-isotope trends from open marine settings in the western United States and Estonia are comparable to the restricted platform in Maryland. In our Ordovician example, local factors appear to have modified the magnitude of the global trends, but not the timing and direction. A remaining question is whether magnitude differences are a function of sedimentation rate and completeness. We continue to test hypotheses of global correlations of C-isotope trends in the Middle-Late Ordovician by utilizing the rapidly changing Sr isotope curve at that time.

  16. Ordovician palaeogeography with new palaeomagnetic data from the Montagne Noire (Southern France)

    Science.gov (United States)

    Nysæther, E.; Torsvik, T. H.; Feist, R.; Walderhaug, H. J.; Eide, E. A.

    2002-10-01

    A joint palaeomagnetic and 40Ar/ 39Ar study has been performed on two olistolithic blocks from the Cabrières Wildflysch in the Montagne Noire region of the Massif Central in France. There, andesitic volcanic and volcaniclastic rocks of Llanvirn-Early Caradoc age (ca 470-458 Ma) occur. Despite extensive secondary alteration, destruction of the dominant magnetic mineral phase and 40Ar/ 39Ar whole rock experiments that demonstrate that the volcanic rocks suffered significant argon loss, a positive fold test and the presence of dual polarities suggest that a primary, Ordovician magnetisation has mostly survived. This is one of the few documented cases where the argon system was substantially reset whilst a subordinate set of small, relatively unaltered magnetite grains, probably hosted in silicates, still carry the original, in this case Ordovician, remanence. The new data show that the Montagne Noire region was located at high southerly latitudes (68° +17/ -15) during the Mid-Ordovician. This latitude represents the location for NW Gondwana of which the Massif Central was a part. Palaeomagnetic data from all the Central European massifs and terranes demonstrate a close link to the Gondwana Margin during the Lower and Middle Ordovician.

  17. A primitive cladid crinoid from the Jiacun Group, Tibet (Darriwilian, Middle Ordovician)

    DEFF Research Database (Denmark)

    Donovan, Stephen K.; Harper, David A.T.; Renbin, Zhan;

    2012-01-01

    A collection of numerous crinoid pluricolumnals from the uppermost Darriwilian (Middle Ordovician) of Tibet were derived from one biological species of crinoid. The specimens were collected from well-lithified, bioclastic shelf limestones of the upper part of the Lower Chiatsun Group, Pygodus serra...

  18. A world-wide reunion of Ordovician & Silurian geologists in Nanjing

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Hosted by the CAS Nanjing Institute of Geology and Paleontology(NIGPAS), the 10th International Symposium on the Ordovician System, the 3rd International Symposium on the Silurian System and the 4th Annual Meeting of the IGCP 503 Project were jointly held from 27 to 30 June in Nanjing, capital of East China's Jiangsu Province.

  19. Brachiopod associations from the Middle Ordovician of the Oslo Region, Norway

    DEFF Research Database (Denmark)

    Candela, Yves; Hansen, Thomas

    2010-01-01

    The marine upper Darriwilian (Middle Ordovician) Elnes Formation of southern Norway contains very rich and diverse invertebrate faunas. Stratigraphically detailed recent collections of these well-preserved faunas have permitted a more thorough description of the various faunal groups and their pr...

  20. Hanadirella: A new problematic arthropod(?) from the Lower Ordovician (Llanvirn) Tabuk Formation, central Saudi Arabia

    NARCIS (Netherlands)

    El-Khayal, A.A.

    1985-01-01

    The new genus Hanadirella - with the type species H. bramkampi - from the Lower Ordovician (Llanvirn) of central Saudi Arabia represents a segmented organism which appears to have an arthropod affinity. The problematic genus is oval hat-shaped, less than 1 mm in diameter. Its affinity and palaeoecol

  1. Middle Ordovician brachiopods from the Stairway Sandstone, Amadeus Basin, central Australia

    DEFF Research Database (Denmark)

    Jakobsen, Kristian Grube; Brock, Glenn A.; Nielsen, Arne Thorshøj

    2014-01-01

    Middle Ordovician brachiopod faunas from the Amadeus Basin, central Australia are poorly known. The Darriwilian Stairway Sandstone was sampled stratigraphically for macrofossils in order to provide new information on marine benthic diversity in this clastic-dominated, shallow-water palaeoenvironm...

  2. Reinterpretation of the Ordovician rotations in NW Argentina and Northern Chile: a consequence of the Precordillera collision?

    Science.gov (United States)

    Spagnuolo, Cecilia M.; Rapalini, Augusto E.; Astini, Ricardo A.

    2011-04-01

    Early Paleozoic paleomagnetic data from NW Argentina and Northern Chile have shown large systematic rotations within two domains: one composed of the Western Puna that yields very large (up to 80°) counter-clockwise rotations, and the other formed by the Famatina Ranges and the Eastern Puna that shows (~40°) clockwise rotations around vertical axes. In several locations, lack of significant rotations in younger rocks constrains this kinematic pattern to have occurred during the Paleozoic. Previous tectonic models have explained these rotations as indicative of rigid-body rotations of large para-autochthonous crustal blocks or terranes. A different but simple tectonic model that accounts for this pattern is presented in which rotations are associated to crustal shortening and tectonic escape due to the collision of the allochthonous terrane of Precordillera in the Late Ordovician. This collision should have generated dextral shear zones in the back arc region of the convergent SW Gondwana margin, where systematic domino-like clockwise rotations of small crustal blocks accommodate crustal shortening. The Western Puna block, bordering the Precordillera terrane to the north, might have rotated counterclockwise as an independent microplate due to tectonic escape processes, in a fashion similar to the present-day relationship between the Anatolia block and the Arabian microplate.

  3. Fracture system influence on the reservoirs rock formation of Ordovician-Devonian carbonates in West Siberia tectonic depression

    Science.gov (United States)

    Koveshnikov, A. E.; Nesterova, A. C.; Dolgaya, T. F.

    2016-09-01

    During the Paleozoic period from the beginning of the Cambrian to the end of the Carboniferous in the boundaries of the West Siberia tectonic depression there occurred the sea, where the carbonate platforms were formed by the limestones accumulation. All the area at the end of the Carboniferous period was turned to land. Resulting from Gertsynskaya folding in the times of Permian - Triassic the formed deposits were folded and denudated to a considerable extent. Besides, the reservoir rocks of the crust of weathering including redeposited one, were formed as a result of hypergenesis, during the continental stand of the area in the near-surface zone. A new geological prospecting unit has been suggested which underlies these crusts of weathering and formed during fracture tectonic processes with hydrothermal-metasomatic limestones reworking and the processes of hydrothermal leaching and dolomitization. So, in the carbonate platforms the system of fissure zones related to tectonic disturbance was formed. This has a dendrite profile where the series of tangential, more thinned fractures deviate from the stem and finish in pores and caverns. The carbonate platforms formation in the West Siberia tectonic depression has been analyzed, their dynamics and gradual increasing from the minimal in Ordovician and Silurian to maximal at the end of the Late Devonian has been shown.

  4. The mafic rocks of Shao La (Kharta, S. Tibet): Ordovician basaltic magmatism in the greater himalayan crystallines of central-eastern Himalaya

    Science.gov (United States)

    Visonà, Dario; Rubatto, Daniela; Villa, Igor M.

    2010-04-01

    evidence that the Bhimphedian Orogeny was still active as late as the Late Ordovician

  5. Distribution and significance of crystalline, perlitic and vesicular textures in the Ordovician Garth Tuff (Wales)

    Science.gov (United States)

    McArthur, A. N.; Cas, R. A. F.; Orton, G. J.

    Diverse spherulitic and granular crystalline fabrics, perlitic textures and fabrics related to the growth and migration of vesicles occur in the Garth Tuff, a largely welded Ordovician ignimbrite. Defining the distribution of such textures helps to constrain the ignimbrite's cooling and degassing history. Suites of spherulitic and perlitic textures closely reflect variation in cooling rates. Seven facies are defined based on the style and intensity of crystallisation: (1) a medium to coarsely crystalline, equigranular facies; (2) an intensely spherulitic facies; (3) a sparsely spherulitic facies; (4) a pectinate facies; (5) a microcrystalline to cryptocrystalline, equigranular facies; (6) a lithophysal facies; and (7) a transitional perlite-pectinate facies. Textural changes from facies 1 to 5 reflect progressively higher cooling rates. Facies 1 occurs in proximal settings in the ignimbrite's core. Facies 2 to 5 successively envelop facies 1, with facies 2 becoming the dominant fabric in the ignimbrite's core in medial settings. Facies 5 is typically developed in the originally glassy perlitic zones at the ignimbrite's welded margins. Crystallisation under hydrous conditions is reflected by second-boiling textures in the sporadically developed lithophysal facies. The seventh facies reflects a subtle interplay between cooling, hydration and crystallisation which locally prevented perlitic fracturing. The distribution of amygdales reflects patterns of volatile migration and entrapment. In the lower levels of the ignimbrite, amygdales occur in irregular concentrations or rare subvertical pipe-like structures. Pipe-like structures attest to fumarolic activity while the ignimbrite was in a rheomorphic state. Amygdales are widespread and evenly distributed in the upper levels of the ignimbrite. However, the top of the welding profile is characterised by a thin, poorly vesiculated, originally vitrophyric horizon that abruptly caps an intense concentration of amygdales

  6. A single gene controls leaf background color in caladium (Araceae) and is tightly linked to genes for leaf main vein color, spotting and rugosity

    Science.gov (United States)

    Cao, Zhe; Sui, Shunzhao; Yang, Qian; Deng, Zhanao

    2017-01-01

    Modern cultivated caladiums (Caladium×hortulanum) are grown for their long-lasting and colorful leaves. Understanding the mode of inheritance for caladium leaf characteristics is critical for plant breeders to select appropriate parents, predict progeny performance, estimate breeding population sizes needed, and increase breeding efficiencies. This study was conducted to determine the mode of inheritance of two leaf background colors (lemon and green) in caladium and to understand their relationships with four other important leaf characteristics including leaf shape, main vein color, spotting, and rugosity. Seven caladium cultivars and three breeding lines were used as parents in 19 crosses, and their progeny were phenotyped for segregation of leaf traits. Results showed that the two leaf background colors are controlled by a single nuclear locus, with two alleles, LEM and lem, which control the dominant lemon and the recessive green leaf background color, respectively. The lemon-colored cultivar ‘Miss Muffet’ and breeding lines UF-52 and UF-53 have a heterozygous genotype LEMlem. Chi-square tests showed that the leaf background color locus LEM is independent from the leaf shape locus F, but is tightly linked to three loci (S, V and RLF) controlling leaf spotting, main vein color, and rugosity in caladium. A linkage map that consists of four loci controlling major caladium leaf characteristics and extends ~15 cM was developed based on the observed recombination frequencies. This is the first report on the mode of inheritance of leaf background colors in caladium and in the Araceae family. The information gained in this study will be very useful for caladium breeding and study of the inheritance of leaf colors in other ornamental aroids, an important group of ornamental plants in the world. PMID:28101369

  7. The origin and initial rise of pelagic cephalopods in the Ordovician.

    Directory of Open Access Journals (Sweden)

    Björn Kröger

    Full Text Available BACKGROUND: During the Ordovician the global diversity increased dramatically at family, genus and species levels. Partially the diversification is explained by an increased nutrient, and phytoplankton availability in the open water. Cephalopods are among the top predators of today's open oceans. Their Ordovician occurrences, diversity evolution and abundance pattern potentially provides information on the evolution of the pelagic food chain. METHODOLOGY/PRINCIPAL FINDINGS: We reconstructed the cephalopod departure from originally exclusively neritic habitats into the pelagic zone by the compilation of occurrence data in offshore paleoenvironments from the Paleobiology Database, and from own data, by evidence of the functional morphology, and the taphonomy of selected cephalopod faunas. The occurrence data show, that cephalopod associations in offshore depositional settings and black shales are characterized by a specific composition, often dominated by orthocerids and lituitids. The siphuncle and conch form of these cephalopods indicate a dominant lifestyle as pelagic, vertical migrants. The frequency distribution of conch sizes and the pattern of epibionts indicate an autochthonous origin of the majority of orthocerid and lituitid shells. The consistent concentration of these cephalopods in deep subtidal sediments, starting from the middle Tremadocian indicates the occupation of the pelagic zone early in the Early Ordovician and a subsequent diversification which peaked during the Darriwilian. CONCLUSIONS/SIGNIFICANCE: The exploitation of the pelagic realm started synchronously in several independent invertebrate clades during the latest Cambrian to Middle Ordovician. The initial rise and diversification of pelagic cephalopods during the Early and Middle Ordovician indicates the establishment of a pelagic food chain sustainable enough for the development of a diverse fauna of large predators. The earliest pelagic cephalopods were slowly

  8. A Laurentian margin back-arc: the Ordovician Wedowee-Emuckfaw-Dahlonega basin

    Science.gov (United States)

    Barineau, Clinton I.; Tull, James F.; Holm-Denoma, Christopher S.

    2015-01-01

    Independent researchers working in the Talladega belt, Ashland-Wedowee-Emuckfaw belt, and Opelika Complex of Alabama, as well as the Dahlonega gold belt and western Inner Piedmont of Alabama, Georgia, and the Carolinas, have mapped stratigraphic sequences unique to each region. Although historically considered distinct terranes of disparate origin, a synthesis of data suggests that each includes lithologic units that formed in an Ordovician back-arc basin (Wedowee-Emuckfaw-Dahlonega basin—WEDB). Rocks in these terranes include varying proportions of metamorphosed mafic and bimodal volcanic rock suites interlayered with deep-water metasedimentary rock sequences. Metavolcanic rocks yield ages that are Early–Middle Ordovician (480–460 Ma) and interlayered metasedimentary units are populated with both Grenville and Early–Middle Ordovician detrital zircons. Metamafic rocks display geochemical trends ranging from mid-oceanic-ridge basalt to arc affinity, similar to modern back-arc basalts. The collective data set limits formation of the WEDB to a suprasubduction system built on and adjacent to upper Neoproterozoic–lower Paleozoic rocks of the passive Laurentian margin at the trailing edge of Iapetus, specifically in a continental margin back-arc setting. Overwhelmingly, the geologic history of the southern Appalachians, including rocks of the WEDB described here, indicates that the Ordovician Taconic orogeny in the southern Appalachians developed in an accretionary orogenic setting instead of the traditional collisional orogenic setting attributed to subduction of the Laurentian margin beneath an exotic or peri-Laurentian arc. Well-studied Cenozoic accretionary orogens provide excellent analogs for Taconic orogenesis, and an accretionary orogenic model for the southern Appalachian Taconic orogeny can account for aspects of Ordovician tectonics not easily explained through collisional orogenesis.

  9. The Cambrian-Ordovician rocks of Sonora, Mexico, and southern Arizona, southwestern margin of North America (Laurentia): chapter 35

    Science.gov (United States)

    Page, William R.; Harris, Alta C.; Repetski, John E.; Derby, James R.; Fritz, R.D.; Longacre, S.A.; Morgan, W.A.; Sternbach, C.A.

    2013-01-01

    Cambrian and Ordovician shelf, platform, and basin rocks are present in Sonora, Mexico, and southern Arizona and were deposited on the southwestern continental margin of North America (Laurentia). Cambrian and Ordovician rocks in Sonora, Mexico, are mostly exposed in scattered outcrops in the northern half of the state. Their discontinuous nature results from extensive Quaternary and Tertiary surficial cover, from Tertiary and Mesozoic granitic batholiths in western Sonora, and from widespread Tertiary volcanic deposits in the Sierra Madre Occidental in eastern Sonora. Cambrian and Ordovician shelf rocks were deposited as part of the the southern miogeocline on the southwestern continental margin of North America.

  10. 滇东北昭通箐门的泥盆纪珊瑚(一)——早泥盆世和中泥盆世早期的四射珊瑚%DEVONIAN RUGOSE CORALS FROM ZHAOTONG, NE YUNNAN (1)——SOME EMSIAN AND EIFELIAN RUGOSE CORALS

    Institute of Scientific and Technical Information of China (English)

    廖卫华; 马学平

    2016-01-01

    云南省昭通市东北郊箐门出露了一条比较完整的泥盆纪浅海相地层剖面,下、中、上三个统均有出露,浅海底栖生物化石丰富,研究基础也相对较好,是研究滇东北地区泥盆纪地层的一条理想剖面.由于地层剖面比较长,沉积厚度比较大,文中仅描述该剖面早泥盆世和中泥盆世早期的四射珊瑚,并讨论有关地层划分和珊瑚群古生物地理亲缘关系.%The rugose corals described in the present paper were collected by one of the authors (Liao Weihua) from the Qingmen section of Zhaotong,NE Yunnan in 1972.These corals,occuring in association with brachiopods (Rostrospirifer ardenensis,Rostrospiri fer tonkinensis,Acrospiri fer orthogonalis,Acrospiri fer lungmenshanensis,Atrypa sp.,Cyrtina sp.,“Delthyris” sp.,Dicoelostrophia beblistriata,Dicoelostrophia punctata,El yta sp.,Eosophragmophora sp.,Howittia sp.,Howellella sp.,Kwangsia cf.yohi,Mesodouvillina orientalis,Nadiastrophia pattei,Parachonetes nasutus,Parathyrisina tangnae,Schuchertella sp.),Stromatoporoids (Clathrodictyon sp.,Anostylostroma sp.,Atelodictyon sp.,Ferestromatopora sp.),and bivalves (Leptodesma ? sp.,Mytilarea sp.),were found in a series of sandstones,mudstones intercalated with marls or argillaceous limestones.The rugose corals described and illustrated comprise 11 species within 8 genera.They include two rugose coral Assemblages in ascending order:The first rugose coral Assemblage (Early Devonian Emsian):Acanthophyllum cf.guitangense Yu et Liao Australoph yllum cyathoph ylloides Hill Calceola intermediata intermediata Yoh Calceola sandalina nanningensis Yoh Cystiphylloides cf.fongi (Yoh) Cystiphylloides mirabile Wedekind et Vollbrecht Edaphophyllum zhaotongense sp.nov.Tryplasma cf.guangxiensis Yu et Liao Xystriphyllum el.devonicum Bulvanker The second rugose coral Assemblage (Middle Devonian Eifelian):Utaratuia yunnanensis sp.nov.X ystri ph yllum h yperbolicum Crickmay Among the first rugose coral Assemblage

  11. A Stranger in the Midst: Searching for Relict Grains from Rare Meteorite Types in Mid-Ordovician Limestone Strata

    Science.gov (United States)

    Martin, E.; Schmitz, B.

    2016-08-01

    A layer of Mid-Ordovician limestone harbors exceptional amounts of L-chondritic chromite grains. The layer also contains grains from potentially rarer types of meteorites, following the discovery of the fossil meteorite Österplana 065.

  12. Periodic anoxic shelf in the Early-Middle Ordovician transition: ichnosedimentologic evidence from west-central Utah, USA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ichnosedimentologic evidence of periodic anoxic shelf in the Early-Middle Ordovician transition includes lower ichnodiversity, shallower bioturbation and burrowing depth (<4 cm ), rare domichnia, tiny Chondrites occupying shallower or shallowest tiering, widely distributed nodules of limonite pseudomorphs after pyrite, occurrence of trace fossils being closely associated with the storm event layers, and stratigraphic successions with orbital cyclostratigraphic architecture. It is suggested that lower atmospheric oxygen level during the Early Paleozoic, the Ordovician radiation, dramatic transgression and warmer temperatures would result in the periodic anoxia in the Early-Middle Ordovician transition. This episode began at the later Early Ordovician and lasted about 3.4 Ma on the basis of orbital cyclostratigraphy.

  13. Evidence For Diffusion Dominant Solute Transport In The Ordovician Sediments Of The Michigan Basin

    Science.gov (United States)

    Sykes, J. F.; Normani, S. D.; Yin, Y.

    2011-12-01

    A Deep Geologic Repository (DGR) for Low and Intermediate Level Radioactive Waste has been proposed by Ontario Power Generation for the Bruce site near Tiverton, Ontario, 225 km northwest of Toronto. The DGR concept envisions a repository excavated at a depth of 680 m within the low permeability (less than 10e-14 m/s) limestone Cobourg Formation beneath 200 m of Ordovician age shale. The attributes of the hydrogeologic environment for the DGR, and the potential for solute transport from a repository, were assessed using numerical models for hypothesis testing and numerical experiments. Data for the analyses included Westbay pressure measurements from the DGR site investigation boreholes. These data indicate that the Cambrian sandstone and the Niagaran Group in the Silurian are over-pressured relative to density corrected hydrostatic levels while the Ordovician limestone and shale are significantly under-pressured. The abnormal pressures provide evidence that solute transport in the low permeable Ordovician sediments is diffusion dominant. Sedimentary basins, when at hydrological equilibrium, normally show a near-hydrostatic pressure distribution. Under certain conditions, some excess pressure or pressure greater than hydrostatic can develop in low-permeability layers or other hydraulically isolated parts of systems. The processes commonly invoked to explain these over-pressures are compaction, hydrocarbon migration, diagenesis, tectonic stress or more simply topographic effects. Explanations of abnormal under-pressures include osmosis, exhumation, glaciation unloading, crustal flexure and the presence of a non-wetting gas phase in pores. A requirement of both abnormal over-pressures and under-pressures is low hydraulic conductivity in either the formation in which the abnormal pressures are observed, or in the overlying and underlying formations. Hydraulic conductivity estimates from straddle packer tests in the DGR boreholes confirm that the hydraulic

  14. Unusual Deep Water sponge assemblage in South China-Witness of the end-Ordovician mass extinction.

    Science.gov (United States)

    Li, Lixia; Feng, Hongzhen; Janussen, Dorte; Reitner, Joachim

    2015-11-05

    There are few sponges known from the end-Ordovician to early-Silurian strata all over the world, and no records of sponge fossils have been found yet in China during this interval. Here we report a unique sponge assemblage spanning the interval of the end-Ordovician mass extinction from the Kaochiapien Formation (Upper Ordovician-Lower Silurian) in South China. This assemblage contains a variety of well-preserved siliceous sponges, including both Burgess Shale-type and modern type taxa. It is clear that this assemblage developed in deep water, low energy ecosystem with less competitors and more vacant niches. Its explosion may be related to the euxinic and anoxic condition as well as the noticeable transgression during the end-Ordovician mass extinction. The excellent preservation of this assemblage is probably due to the rapid burial by mud turbidites. This unusual sponge assemblage provides a link between the Burgess Shale-type deep water sponges and the modern forms. It gives an excellent insight into the deep sea palaeoecology and the macroevolution of Phanerozoic sponges, and opens a new window to investigate the marine ecosystem before and after the end-Ordovician mass extinction. It also offers potential to search for exceptional fossil biota across the Ordovician-Silurian boundary interval in China.

  15. Unusual Deep Water sponge assemblage in South China—Witness of the end-Ordovician mass extinction

    Science.gov (United States)

    Li, Lixia; Feng, Hongzhen; Janussen, Dorte; Reitner, Joachim

    2015-11-01

    There are few sponges known from the end-Ordovician to early-Silurian strata all over the world, and no records of sponge fossils have been found yet in China during this interval. Here we report a unique sponge assemblage spanning the interval of the end-Ordovician mass extinction from the Kaochiapien Formation (Upper Ordovician-Lower Silurian) in South China. This assemblage contains a variety of well-preserved siliceous sponges, including both Burgess Shale-type and modern type taxa. It is clear that this assemblage developed in deep water, low energy ecosystem with less competitors and more vacant niches. Its explosion may be related to the euxinic and anoxic condition as well as the noticeable transgression during the end-Ordovician mass extinction. The excellent preservation of this assemblage is probably due to the rapid burial by mud turbidites. This unusual sponge assemblage provides a link between the Burgess Shale-type deep water sponges and the modern forms. It gives an excellent insight into the deep sea palaeoecology and the macroevolution of Phanerozoic sponges, and opens a new window to investigate the marine ecosystem before and after the end-Ordovician mass extinction. It also offers potential to search for exceptional fossil biota across the Ordovician-Silurian boundary interval in China.

  16. Did the amalgamation of continents drive the end Ordovician mass extinctions?

    DEFF Research Database (Denmark)

    Mac Ørum Rasmussen, Christian; Harper, David Alexander Taylor

    2011-01-01

    Global biodiversity has been punctuated throughout the Phanerozoic by extinction events that vary in their degree of intensity and devastation. The mass extinction event that occurred at the end of the Ordovician Period rapidly removed a wide range of species. Because taxonomic loss occurred during...... – was not the sole reason for the crisis. Based on a large, bibliographic database of rhynchonelliform brachiopods that specifically operates within very narrow time-slices where every locality has been precisely georeferenced for the Upper Ordovician–Lower Silurian interval, we show that the extinctions were...... the extent of the extinctions and the subsequent diversity rebound, demonstrates that a reduction in ¿-diversity was perhaps the most important manifestation of the end Ordovician crisis and further raises the question whether this could be applied to other large Phanerozoic perturbations in biodiversity...

  17. Remains of early Ordovician mantle-derived magmatism in the Santander Massif (Colombian Eastern Cordillera)

    Science.gov (United States)

    Mantilla Figueroa, Luis C.; Bissig, Thomas; Cottle, John M.; Hart, Craig J. R.

    2012-10-01

    An Early Ordovician magmatic event has been documented in the Santander Massif (north-Eastern Cordillera, Colombia). Three U/Pb laser ablation ages of 477 ± 2 Ma (Arenig), were obtained from metamorphosed and foliated calc-alkaline diorites. The 176Hf/177Hf values in zircons from these meta-diorites, yielded epsilon Hf values (ɛHft) > 0 (Mean = 2 ± 1, at 477 Ma). These data allow interpretation of the origin of these zircons from a radiogenic initial Hf isotope source, which is characteristic of the Earth's mantle. This, together with the fact that the rocks have been affected subsequently by tectonometamorphic processes, suggests that the early Ordovician diorites have been emplaced in a supra-subduction tectonic setting, related to onset of the Iapetus Ocean closure.

  18. A new glyptorthid species (Brachiopoda: Orthida from the Upper Ordovician of Estonia

    Directory of Open Access Journals (Sweden)

    Linda Hints

    2010-09-01

    Full Text Available A new glyptorthid brachiopod species Bassettella alata with surface pits and lamellose frills is described from the Upper Ordovician Haljala and Keila stages of northern Estonia. The new species appears in the Jõhvi Substage of theHaljala Stage (mid-Sandbian and is somewhat younger than the type species B. ;gracilis appearing in the lower Idavere Substage of the same stage in NW Russia. In the uppermost Keila Stage (lowermost Katian, B. ;alata belongs to a mixed faunal association of the marginal facies of the Vasalemma Formation comprising the oldest Ordovician reefs in Estonia. The distribution pattern of brachiopods of the genus Bassettella shows a westward shift in time and changes in shell morphology from subrectangular to subtriangular with alate cardinal extremities.

  19. First record of the Ordovician fauna in Mila-Kuh, eastern Alborz, northern Iran

    Directory of Open Access Journals (Sweden)

    Mohammad-Reza Kebria-ee Zadeh

    2015-05-01

    Full Text Available Restudy of the Cambrian–Ordovician boundary beds, traditionally assigned to the Mila Formation Member 5 in Mila-Kuh, northern Iran, for the first time provides convincing evidence of the Early Ordovician (Tremadocian age of the uppermost part of the Mila Formation. Two succeeding trilobite assemblages typifying the Asaphellus inflatus–Dactylocephalus and Psilocephalina lubrica associations have been recognized in the uppermost part of the unit. The Tremadocian trilobite fauna of Mila-Kuh shows close similarity to contemporaneous trilobite faunas of South China down to the species level, while affinity to the Tremadocian fauna of Central Iran is low. The trilobite species Dactylocephalus levificatus and brachiopod species Tritoechia tenuis from the Tremadocian of Mila-Kuh are new to science.

  20. The conodont Iapetognathus and its value for defining the base of the Ordovician System

    Science.gov (United States)

    Miller, J. E.; Repetski, John E.; Nicoll, R. S.; Nowlan, G. S.; Ethington, R. L.

    2014-01-01

    Nicoll et al. (1999, Brigham Young University Geology Studies 44, 27–101) published the taxonomy of species of the ramiform conodont Iapetognathus Landing in Fortey et al. (1982, The Cambrian–Ordovician boundary: sections, fossil distributions, and correlations, National Museum of Wales, Geological Series No. 3, Cardiff, 95–129) and its ancestorIapetonudus Nicoll et al., 1999. Cooper et al. (2001, Episodes 24, 19–28) used the First Appearance Datum of Iapetognathus fluctivagus Nicoll et al., 1999 to mark the base of the Ordovician System at Green Point, Newfoundland. Terfelt et al. (2012, Lethaia 45, 227–237) re-evaluated Iapetognathus at Green Point and made several taxonomic and stratigraphic conclusions, nearly all of which we refute herein.

  1. Conodont biostratigraphy in the Middle–Upper Ordovician boundary beds of Estonia

    Directory of Open Access Journals (Sweden)

    Viira, Viive

    2008-03-01

    Full Text Available Conodonts of the uppermost Uhaku, the Kukruse, and the lower Haljala stages (uppermost Darriwilian and lower Sandbian of Estonia are discussed. The distribution of conodonts within the Pygodus serra, P. anserinus, and Amorphognathus tvaerensis zones is considered on the basis of 2 outcrop and 15 drill core sections. Judging by the Global Stratotype Section, Fågelsång, Sweden, the base of the Upper Ordovician Series should be lower than the first appearance of A. tvaerensis. The Estonian material shows that elements of A. tvaerensis from the lowermost range of the species are of a morphotype similar to A. inaequalis. It is proposed that the A. inaequalis Subzone be upgraded to the A. inaequalis Zone. The best level for the Middle–Upper Ordovician boundary in Estonia is at the lower boundary of the Kukruse Stage below the appearance of A. tvaerensis and/or A. inaequalis.

  2. Possible impact event in the Late Cambrian

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The repeated investigation of the Batyrbay section has been done by the authors. Today we see increasing of interest to revising of volumes and boundaries of Stages and Series in the Cambrian and Ordovician,as well as to the events of this time. In this work the description of iron spherules and particles, found in the deep-water limestone layer of the conodont Cordylodus primitivus Zone in the middle Upper Cambrian of the Batyrbay section, Malyi Karatau of South Kazakhstan, and formed during the time of global sea-level changes known as a world-wide Lange Ranch Eustatic event, have been done. From our point of view, finds of iron spherules and particles may evidence about new unknown yet Event of cosmic origin, i.e. falling of a meteorite on Earth in the middle Late Cambrian.

  3. A new glyptorthid species (Brachiopoda: Orthida) from the Upper Ordovician of Estonia

    OpenAIRE

    Linda Hints

    2010-01-01

    A new glyptorthid brachiopod species Bassettella alata with surface pits and lamellose frills is described from the Upper Ordovician Haljala and Keila stages of northern Estonia. The new species appears in the Jõhvi Substage of theHaljala Stage (mid-Sandbian) and is somewhat younger than the type species B. ;gracilis appearing in the lower Idavere Substage of the same stage in NW Russia. In the uppermost Keila Stage (lowermost Katian), B. ;alata belongs to a mixed faunal association of the ma...

  4. New biostratigraphically important chitinozoans from the Kukruse Regional Stage, Upper Ordovician of Baltoscandia

    Directory of Open Access Journals (Sweden)

    Jaak Nõlvak

    2015-08-01

    Full Text Available Three new chitinozoan species, Conochitina savalaensis, Conochitina viruana and Belonechitina intonsa, are described. All these species are stratigraphically restricted to the Kukruse age (lowermost Sandbian, Laufeldochitina stentor chitinozoan Zone and have been recorded in numerous East Baltic sections as well as from NE Poland and NW Ukraine and Sweden. Their short temporal range and relative abundance point to a great biostratigraphical value for regional correlations near the base of the Upper Ordovician.

  5. Basic Ordovician magmatism of the Spanish Central System: Constraints on the source and geodynamic setting

    Science.gov (United States)

    Orejana, D.; Villaseca, C.; Merino Martínez, E.

    2017-07-01

    New geochemical and geochronological data obtained from metabasites intrusive into pre-Floian metasedimentary and metaigneous rocks of the Spanish Central System (Revenga and El Caloco sectors) represent a complex pre-Variscan magmatic event. Analysed samples exhibit tholeiitic affinity but relatively high incompatible element contents. These rocks can be distinguished from similar tholeiitic SCS metabasites because they represent more primitive liquids with higher metal (Cr, Ni) and LILE contents and display a slightly enriched isotopic (Sr, Nd) composition. These data point to the involvement of several mantle sources including lithospheric sections with a crustal imprint. Two samples yield Ordovician U-Pb zircon intrusion ages of 473.1 (+ 3.8/- 6.8) and 453.3 ± 4.6 Ma. This episode of basic magmatism is not coetaneous with the abundant Cambrian-Ordovician felsic orthogneisses of the Central Iberian Zone and likely represents a rifting context (Rheic Ocean opening) which started about 477 Ma. A comparison with Lower to Middle Paleozoic magmatic rocks from other west European terranes implies a heterogeneous evolution from the Ediacaran to Middle Paleozoic in the northern margin of Gondwana. While western terranes (e.g., Armorican Massif, Saxo-Thuringian Zone, Ossa-Morena Zone) display monotonous shelf sedimentation and magmatic quiescence from the Upper Ordovician to Variscan collision, eastern terranes (e.g., Central Iberian Zone, Corsica-Sardinia, Alps, Pyrenees) exhibit magmatism of contrasting geochemical affinity, including basic alkaline and tholeiitic series, indicative of a more complex tectonic evolution.

  6. Ordovician graptolite-bearing strata in southern Jiangxi with a special reference to the Kwangsian Orogeny

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Ordovician graptolite sequence of the Yongxin-Chongyi area in southern Jiangxi was suggested as a standard for the correlation of Ordovician in the Zhujiang region of South China. Based on a restudy of the Upper Ordovician graptolites, the Shikou and Huamianlong formations are recognized herein as a part of the Hanjiang Formation, corresponding only to the Dipla-canthograptus caudatus-Diplacanthograptus spiniferus Zone. Two graptolite zones in the Longxi Formation of Yongxin and Chongyi, the Nemagraptus gracilis Zone and Climacograptus bicornis Zone, are redefined here. A rapid replacement of facies from the typical deep-water graptolitic black shale of Longxi Formation to the rapidly-accumulated, shallow-water clastic deposits of Hanjiang Formation indicates the tectonic initiation of the Kwangsian Orogeny. The thick clastic deposits of the Han-jiang Formation are proposed to come from a nearby source area that rose during the Kwangsian Orogeny. The D. caudatus-D. spiniferus graptolite Zone of the Hanjiang Formation indicates the initiation time of this tectonic event.

  7. Contact metamorphism in Middle Ordovician arc rocks (SW Sardinia, Italy): New paleogeographic constraints

    Science.gov (United States)

    Costamagna, Luca Giacomo; Elter, Franco Marco; Gaggero, Laura; Mantovani, Federico

    2016-11-01

    In the early Cambrian Bithia Formation in the Variscan foreland of Sardinia, a Middle Ordovician granitic intrusion (478-457 Ma) is hosted by marly metasedimentary rocks that were affected by high-temperature (HT) metamorphism. A detailed structural-petrographical transect was conducted through the granitic intrusion and its host rocks. Field data and relationships between HT/low-pressure (LP) mineral assemblages in the metasedimentary rocks (Grt + Wo + Ves in carbonate lenses and And in pelite) demonstrate that the study area was affected by a polyphase HT overprint (I: T = 520-620 °C at XCO2 = 0.1, P: 0.2-0.4 GPa; and II: T = 600-670 °C at XCO2 = 0.1, P = 0.2-0.4 GPa) that pre-dates the Variscan tectonic, metamorphic, and igneous phases. In the Canigò or Canigou Massif (Eastern Pyrenees), the Somail Massif (Montagne Noire), and the Ruitor Massif (Internal Massifs, NW Alps), Middle Ordovician orthogneiss with relict igneous textures are deciphered despite being overprinted by Variscan amphibolite-to-granulite-facies metamorphism and subsequent Alpine low-grade metamorphism. Comparisons of associated igneous and metasedimentary rocks in the Sardinia foreland with the High-Grade Metamorphic Complex in the Variscan Axial Zone and the Canigou Massif indicate a convergent Middle Ordovician evolution that was overprinted by HT Variscan metamorphism.

  8. Palaeomagnetism of Middle Ordovician Carbonate Sequence, Vaivara Sinimäed Area, Northeast Estonia, Baltica

    Science.gov (United States)

    Plado, Jüri; Preeden, Ulla; JÕeleht, Argo; Pesonen, Lauri J.; Mertanen, Satu

    2016-10-01

    The hill range of Vaivara Sinimäed in northeast Estonia consists of several narrow east- to northeast-trending glaciotectonic fold structures. The folds include tilted (dips 4-75°) Middle Ordovician (early Darriwilian) layered carbonate strata that were studied by mineralogical, palaeomagnetic, and rock magnetic methods in order to specify the postsedimentational history of the area and to obtain a better control over the palaeogeographic position of Baltica during the Ordovician. Mineralogical studies revealed that (titano)magnetite, hematite, and goethite are carriers of magnetization. Based on data from 5 sites that positively passed a DC tilt test, a south-easterly downward directed component A ( D ref = 154.6°± 15.3°, I ref = 60.9°± 9.7°) was identified. The component is carried by (titano)magnetite, dates to the Middle Ordovician ( Plat = 17.9°, Plon = 47.3°, K = 46.7, A95 = 11.3°), and places Baltica at mid-southerly latitudes. Observations suggest that in sites that do not pass the tilt test, the glaciotectonic event has caused some rotation of blocks around their vertical axis.

  9. Quantitative evaluation of microplankton palaeobiogeography in the Ordovician-Early Silurian of the northern Trans European Suture Zone: implications for the timing of the Avalonia-Baltica collision.

    Science.gov (United States)

    Vecoli, M; Samuelsson, J

    2001-05-01

    Quantitative analysis of assemblage similarity among chitinozoan and acritarch associations recovered from various sedimentary sequences across the Trans European Suture Zone (TESZ; southern Baltic Sea and northern Germany region), permits evaluation of changes in microplankton palaeobiogeography during the Ordovician in the study area. The present data confirm strong palaeobiogeographic differences between the lower Ordovician of the Rügen area, and the coeval domains of the East European Platform (EEP), corroborating the idea that the subsurface of Rügen should be considered palaeogeographically as the eastern extension of Avalonia.Cluster analysis of chitinozoan assemblages from numerous wells in the Rügen area, and one well from the southern margin of the EEP indicates that chitinozoan bioprovincialism reached its maximum during the Llanvirn; during this period, the Rügen microplankton communities were clearly Gondwanan in character. Calculations using the coefficient of similarity support the conclusion of a high similarity between Llanvirn acritarch assemblages from the Rügen subsurface and from coeval Perigondwana localities (e.g. Tunisia). Since the early Caradoc, this Gondwanan affinity of the Rügen microfossils starts to lessen, and becomes negligible during the late Caradoc. During latest Caradoc-early Ashgill through Llandovery times the chitinozoan assemblages from either side of the TESZ are undistinguishable. If palaeobiogeographical differentiation is primarily related to palaeolatitudinal distance, then the present data support closure of the Tornquist Ocean during late Caradoc-Ashgill times. The presence of reworked Llanvirn acritarchs of Perigondwanan affinity in middle Ashgill sedimentary sequences at the southern margin of the EEP, clearly shows that by this time erosion of an uplifted area was taking place. Accordingly, the closure of the Tornquist Ocean, and consequent Avalonia-Baltica collision must have taken place during the time

  10. South East Asia as a part of an Ordovician Gondwanaland—a palaeobiogeographic test of a tectonic hypothesis

    Science.gov (United States)

    Burrett, Clive; Stait, Bryan

    1985-10-01

    The hypothesis that Thailand and Malaysia (the Sibumasu block) were adjacent to Australia in the Early Palaeozoic has been tested by an examination of the Ordovician sequences and faunas of Sibumasu and Australia. The relatively stenogeographic nautiloids of the two areas are remarkably similar and have a Simpson Index of 0.92 at the generic level. Two new genera of discosorids are restricted to the two blocks and Georgina and Mesaktoceras are found elsewhere only in Tibet. Very close affinities are also evident between the gastropod, polyplacophoran and rostroconch molluscs. The Ordovician brachiopod faunas are also very close including the genus Spanodonta. Other very close similarities are found between the Upper Cambrian trilobite faunas and the Ordovician conodonts and stromatoporoids. No Ordovician faunas younger than Upper Whiterockian were found during this study in either northern Australia or Sibumasu and a stratigraphic gap probably exists from the Upper Whiterockian to the Upper Ordovician over most of the two blocks. These remarkably close faunal similarities are good evidence in favour of the hypothesis that Sibumasu was adjacent to Australia during the Early Palaeozoic. Similarly close faunal relationships between North China, South East Asia, Tibet and Australia may also suggest close proximity of those blocks during the Early Palaeozoic.

  11. Late Budgets

    DEFF Research Database (Denmark)

    Andersen, Asger Lau; Lassen, David Dreyer; Nielsen, Lasse Holbøll Westh

    The budget forms the legal basis of government spending. If a budget is not in place at the beginning of the fiscal year, planning as well as current spending are jeopardized and government shutdown may result. This paper develops a continuous-time war-of-attrition model of budgeting...... in a presidential style-democracy to explain the duration of budget negotiations. We build our model around budget baselines as reference points for loss averse negotiators. We derive three testable hypotheses: there are more late budgets, and they are more late, when fiscal circumstances change; when such changes...... are negative rather than positive; and when there is divided government. We test the hypotheses of the model using a unique data set of late budgets for US state governments, based on dates of budget approval collected from news reports and a survey of state budget o¢ cers for the period 1988...

  12. Late Budgets

    DEFF Research Database (Denmark)

    Andersen, Asger Lau; Lassen, David Dreyer; Nielsen, Lasse Holbøll Westh

    are negative rather than positive; and when there is divided government. We test the hypotheses of the model using a unique data set of late budgets for US state governments, based on dates of budget approval collected from news reports and a survey of state budget o¢ cers for the period 1988......The budget forms the legal basis of government spending. If a budget is not in place at the beginning of the fiscal year, planning as well as current spending are jeopardized and government shutdown may result. This paper develops a continuous-time war-of-attrition model of budgeting...... in a presidential style-democracy to explain the duration of budget negotiations. We build our model around budget baselines as reference points for loss averse negotiators. We derive three testable hypotheses: there are more late budgets, and they are more late, when fiscal circumstances change; when such changes...

  13. Carbon isotope composition and correlation across the Cambrian-Ordovician boundary in Kalpin Region of the Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    JING XiuChun; DENG ShengHui; ZHAO ZongJu; LU YuanZheng; ZHANG ShiBen

    2008-01-01

    Biostratigraphically constrained sequences at the Wushi Yingshan and Kalpin Cement Plant sections (Kalpin Region; Tarim Basin) were densely sampled for geochemical studies.Carbonates across the Cambrian-Ordovician boundary of both sections mainly record negative carbon isotope values.Stable isotope curves show four negative and four positive excursions appearing alternately at the Wushi Yingshan section and five negative alternating with five positive excursions at the Kalpin Cement Plant section.The carbon isotope logs of these two sections are correlated with the international Cambrian-Ordovician boundary key sections: (1) Dayangcha section in China, (2) Green Point section in Canada, (3) Black mountain section in Australia and (4) Lowson Cove section in USA.These correlations suggest that the Cambrian-Ordovician boundary of the Wushi Yingshan section and the Kalpin Cement Plant section can be placed within a particular horizon that also corresponds to the observed biostratigraphic units.

  14. Carbon isotope composition and correlation across the Cambrian-Ordovician boundary in Kalpin Region of the Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Biostratigraphically constrained sequences at the Wushi Yingshan and Kalpin Cement Plant sections (Kalpin Region; Tarim Basin) were densely sampled for geochemical studies. Carbonates across the Cambrian-Ordovician boundary of both sections mainly record negative carbon isotope values. Stable isotope curves show four negative and four positive excursions appearing alternately at the Wushi Yingshan section and five negative alternating with five positive excursions at the Kalpin Cement Plant section. The carbon isotope logs of these two sections are correlated with the international Cambrian-Ordovician boundary key sections: (1) Dayangcha section in China, (2) Green Point section in Canada, (3) Black mountain section in Australia and (4) Lowson Cove section in USA. These correlations suggest that the Cambrian-Ordovician boundary of the Wushi Yingshan section and the Kalpin Cement Plant section can be placed within a particular horizon that also corresponds to the observed biostratigraphic units.

  15. δ13C chemostratigraphy in the upper Tremadocian through lower Katian (Ordovician carbonate succession of the Siljan district, central Sweden

    Directory of Open Access Journals (Sweden)

    Oliver Lehnert

    2014-12-01

    Full Text Available Based on δ13C data from two drillcores recovered from the Siljan district, we present a first continuous carbon isotope record of the upper Tremadocian–lower Katian limestone succession of central Sweden. New names for some isotopic carbon excursions from the Cambrian–Ordovician boundary through the basal Darriwilian are introduced. The Mora 001 core from the western part of the Siljan impact structure ranges through the Lower–Middle Ordovician, whereas the Solberga 1 core from its eastern part ranges through the Middle–lower Upper Ordovician. Upper Tremadocian and Floian units are extremely condensed and include extensive stratigraphic gaps. Multiple hardgrounds, sometimes with minor karstic overprint, imply recurrent periods of erosion and/or non-deposition. Like in other parts of Sweden, the Dapingian and Darriwilian succession is characterized by a relatively complete sedimentary record and low sedimentation rates.

  16. Dolomitization and sedimentary cyclicity of the Ordovician, Silurian, and Devonian rocks in South Estonia

    Directory of Open Access Journals (Sweden)

    Kallaste, Toivo

    2006-03-01

    Full Text Available The distribution and composition of dolomitized rocks and stoichiometry of dolomite in southern Estonia in the Ordovician, Silurian, and Devonian were studied on the background of the facies, sedimentary cyclicity (nine shallowing-up cycles, and evolution of the palaeobasins. The composition of rocks and lattice parameters of dolomite were investigated using the X-ray diffraction, X-ray fluorescence, titration and gravimetric analyses, and porosity measurements. The formation of dolostones is directly determined by the cyclic evolution of palaeobasins. Dolomitized rocks belong to the shallow-water inner shelf or tidal/lagoonal facies belt of regressive phases of sedimentary cycles. Sediments of the deep shelf/transitional environment and transgressive phases are not dolomitized. The most stoichiometric is secondary replacive dolomite of Silurian and upper Ordovician dolostones, formed during the early diagenesis of normal-marine (saline shallow-shelf calcitic sediments. The content of insoluble residue does not affect the stoichiometry. The changes in lattice parameters are induced by the Ca/Mg ratio in the dolomite lattice. The dolomite of the dolostones contacting limestone or containing calcite has an expanded lattice. The primary (syngenetic dolostone of the lagoonal or tidal flat belt has also an expanded lattice. No dolomitizing effect of the waters of the Devonian palaeobasin on the underlying rocks was revealed. The whole data set of the studied dolostones is consistent with the marine water environment in the palaeobasin at the corresponding time and shows no sign of the inflow of external fluids. It suggests that the microbial model of dolomite formation may characterize the Ordovician, Silurian, and Devonian in southern Estonia. The occurrence of dolostones between undolomitized rocks limits the time of dolomitization to the early diagenetic stage.

  17. Geochemical changes across the Ordovician-Silurian transition on the Yangtze Platform,South China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The trace element and rare earth element(REE) variations across the Ordovician-Silurian succession are presented from two outcrop sections on the Yangtze Platform:the Nanbazi section,Guizhou Province,deposited in a shallow platform interior setting,and the Wangjiawan section,Hubei Province,deposited in a deeper basinal environment.Geochemical analysis of closely spaced samples through three intervals,the Wufeng,Guanyinqiao and Longmaxi,revealed vast palaeoceanographic changes.Some geochemical proxies,including Th/U,Ni/Co,V/Cr,and V/(V+Ni) ratios,together with sedimentary facies and biotic data,indicate that an anoxic condition on the most of the Yangtze Platform during the Wufeng and Longmaxi intervals,but an oxic condition during the Guanyinqiao time.The shift of the anoxic to the oxic environment during the Guanyinqiao time coincided with a global sea-level lowstand,in parallel with the global glaciation.The Longmaxian anoxic environment was a result of a global sea-level rise,which may be synchronized with a mainly catastrophic event in the latest Ordovician.Although the two sections generally show similar variation patterns of trace and REE concentrations and some element ratios,a minor difference occurs between the Wangjiawan and Nanbazi sections,likely reflecting a difference in depositional setting during the accumulation.Such an oceanic oxygen-level variation may add a useful constraint to the current arguments on the cause and consequence of the latest Ordovician mass extinction.

  18. Digestive structures in Ordovician trilobites Colpocoryphe and Flexicalymene from the Barrandian area of Czech Republic

    Directory of Open Access Journals (Sweden)

    Oldřich Fatka

    2015-11-01

    Full Text Available Two recently discovered specimens of the abundant calymenoid trilobite Colpocoryphe Novák in Perner, 1918 from the Middle Ordovician Šárka Formation and one specimen of Flexicalymene (Flexicalymene pragensis Vaněk & Vokáč, 1997 from the Upper Ordovician Bohdalec Formation, all from the Prague Basin, display remains of the digestive system. In Colpocoryphe, an internal mould of an articulated exoskeleton contains a post-stomach part of the alimentary canal preserved through the narrow axial region of the occipital ring, all thoracic segments as well as in the axial part of the pygidial shield. The anterior part of the digestive system is poorly known as the specimen shows the hypostome preserved in situ and the space between the glabella and the hypostome is represented by an empty cavity associated with probable remains of gut diverticulae on both sides of the cephalon. The second, incomplete specimen consists of five posterior thoracic segments articulated with the pygidium. The axial region of this specimen is preserved with a clearly discernible segmented intestine which terminates at the axial tip and then bends ventrally. In an enrolled specimen of Flexicalymene pragensis, supposed remains of the alimentary tract are comparatively poorly preserved but discernible in the middle and posterior parts of the thoracic axis and in the anterior part of the pygidial axis. Digestive structures within the family Calymenidae have not been described previously. Earlier discoveries of the digestive system in Ordovician trilobites of the Barrandian area are briefly reviewed.

  19. New Data on Ordovician Eocrinoids and Paracrinoids of the Baltic Region

    Science.gov (United States)

    Rozhnov, S.

    2009-04-01

    Eocrinoids are widespread in the Ordovician beds of the Baltic Region, often dominating in benthic communities of the Middle Ordovician. They are represented by 12 genera. New records allow the improvement of their morphology, stratigraphic and geographical distribution. Rhipidocystis was one of the first to appear in the Baltic basin (Upper Billingen of the eastern Baltic Basin); it reached its acme in the Volkhov and became scarce rare in subsequent strata, although survived up to the Uhaku. In the Azeri or Lasnamyagi, it gave rise to the close related genus Neorhipidocystis, which rarely occurs in the Lasnamyagi, Uhaku and Kukruze Regional Stages. New data on the arrangement of pores, morphology variability in the brachiols strongly suggest that Rhipidocystis is close to Volkhovian Paracryptocrinites and Cryptocrinites, which evolved from the last genus in the Azeri. Bockia, which occurs in the Azeri, Lasnamyagi, Uhaku and Kukruze, is closely related to Cryptocrinites and differs from it in the considerably larger size, greater number of plates, extended apertural part, and branching brachiolas. These five genera belong to the same lineage of closely related Ordovician eocrinoids, which is named the cryptocrinid-rhipidocystid lineage. In North America, a similar eocrinoid lineage developed in parallel. The two lineages probably evolved from a common ancestor, which inhabited eastern Gondwana in the Early Ordovician. Plates of Rhopalocystidae are abundant in the Volkhovian Regional stage; they show distinctive sutural pores, which are characteristic of the other branch of Ordovician eocrinoids, widespread in the northern marginal area of Gondwana. The thecal fragments, which are scarce in the Baltic Region, allow the reconstruction of only the distal part; however, it is evident that the Baltic genus differs sharply in shape from Gondwanian rhopalocystids. A unique eocrinoid specimen, with a spherical theca composed of many plates and a column similar in

  20. 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.

  1. Graphic correlation of Argentine Precordillera and North American Lower/Middle Ordovician sections

    Institute of Scientific and Technical Information of China (English)

    Walter C.Sweet; Guillermo L.Albanesi

    2006-01-01

    @@ Present work demonstrates that a level equivalent to the proposed Whiterockian basal GSSP can be located graphically in a composite section anchored by the Niquivil section of the Argentine Precordillera. The FAD of Cooperignathus aranda in the Niquivil composite section, a candidate for GSSP of the Lower/Middle Ordovician boundary, projects to a level very close to the FAD of Tripodus laevis in the Whiterockian reference section. The conodont-based framework reported here includes the potential for recognition of the proposed Whiterock Canyon-based GSSP, the Cooperignathus aranda-based GSSP, and, possibly, the Baltoniodus triangularisbased GSSP, recently proposed.

  2. Hydraulic testing of low-permeability Silurian and Ordovician strata, Michigan Basin, southwestern Ontario

    Science.gov (United States)

    Beauheim, Richard L.; Roberts, Randall M.; Avis, John D.

    2014-02-01

    Straddle-packer hydraulic testing was performed in 31 Silurian intervals and 66 Ordovician intervals in six deep boreholes at the Bruce nuclear site, located near Tiverton, Ontario, as part of site-characterization activities for a proposed deep geologic repository (DGR) for low- and intermediate-level radioactive waste. The straddle-packer assembly incorporated a hydraulic piston to initiate in situ pulse tests within low hydraulic conductivity (condition and relative to the overlying Silurian strata and underlying Black River Group and Cambrian strata. These underpressures could not persist if hydraulic conductivities were not as low as those measured.

  3. Cambrian-lower Middle Ordovician passive carbonate margin, southern Appalachians: Chapter 14

    Science.gov (United States)

    Read, J. Fred; Repetski, John E.

    2012-01-01

    The southern Appalachian part of the Cambrian–Ordovician passive margin succession of the great American carbonate bank extends from the Lower Cambrian to the lower Middle Ordovician, is as much as 3.5 km (2.2 mi) thick, and has long-term subsidence rates exceeding 5 cm (2 in.)/k.y. Subsiding depocenters separated by arches controlled sediment thickness. The succession consists of five supersequences, each of which contains several third-order sequences, and numerous meter-scale parasequences. Siliciclastic-prone supersequence 1 (Lower Cambrian Chilhowee Group fluvial rift clastics grading up into shelf siliciclastics) underlies the passive margin carbonates. Supersequence 2 consists of the Lower Cambrian Shady Dolomite–Rome-Waynesboro Formations. This is a shallowing-upward ramp succession of thinly bedded to nodular lime mudstones up into carbonate mud-mound facies, overlain by lowstand quartzose carbonates, and then a rimmed shelf succession capped by highly cyclic regressive carbonates and red beds (Rome-Waynesboro Formations). Foreslope facies include megabreccias, grainstone, and thin-bedded carbonate turbidites and deep-water rhythmites. Supersequence 3 rests on a major unconformity and consists of a Middle Cambrian differentiated rimmed shelf carbonate with highly cyclic facies (Elbrook Formation) extending in from the rim and passing via an oolitic ramp into a large structurally controlled intrashelf basin (Conasauga Shale). Filling of the intrashelf basin caused widespread deposition of thin quartz sandstones at the base of supersequence 4, overlain by widespread cyclic carbonates (Upper Cambrian lower Knox Group Copper Ridge Dolomite in the south; Conococheague Formation in the north). Supersequence 5 (Lower Ordovician upper Knox in the south; Lower to Middle Ordovician Beekmantown Group in the north) has a basal quartz sandstone-prone unit, overlain by cyclic ramp carbonates, that grade downdip into thrombolite grainstone and then storm

  4. 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......-organisms. Due to strong morphological and ecological similarities between galeate fossils and dasycladalean cysts, and the antiquity of this algal order, galeates may be positioned within green algae, more specifically Dasycladales. The unique morphology of the operculum-bearing microbiota would have required...

  5. Rugose corals at the Tournaisian-Viséan transition in the Central Taurides (S Turkey) - Palaeobiogeography and palaeoceanography of the Asian Gondwana margin

    Science.gov (United States)

    Denayer, Julien

    2015-02-01

    This paper gives the first taxonomic description of the Upper Tournaisian-Lower Viséan rugose coral fauna of the Yaricak Formation (Aladag Unit, Central Taurides, South Turkey). Fifteen species belonging to twelve genera were identified, one species is newly described: Eokoninckocarinia gemmina. The corals are stratigraphically distributed in four assemblages. The two typical assemblages of the Upper Tournaisian are composed of widely distributed taxa (Uralinia, Caninia, Proheterelasma, Zaphrentites). The assemblage crossing the Tournaisian-Viséan boundary is characterized by Eurasian and cosmopolitan and widely distributed taxa (Calmiussiphyllum, Siphonophyllia, Bifossularia Amygdalophyllum, Caninophyllum, Keyserlingophyllum) and Asian taxa (Kueichouphyllum). The youngest assemblage, dominated by Eokoninckocarinia gemmina sp. nov., has yielded foraminifers Moliniacian (Lower Viséan) in age. These assemblages form a low diversity level-bottom community which is typical of the South Palaeotethys 'Kueichouphyllum Zone' extending along the Asian margin of Gondwana (Cimmerian Terrane) during Lower Carboniferous times. As in the other Cimmerian blocks, all the corals are solitary and colonial taxa are virtually absent. This absence is tentatively explained by the high palaeolatitude (c. 50°S) position of the Cimmerian Terrane in the southern part of the Palaeotethys Ocean for this time slice. A cold-water palaeo-current running eastward along the Gondwana margin might also be considered as it possibly could explain the wide distribution of the Kueichouphyllum fauna, restricted east of Africa in the southern coast of the Palaeotethys. Palaeoceanography, palaeoclimate and facies issues are discussed as possible causes of the diversity gradient observed between the eastern (Australia, Malaya) and the western (North Africa) margin of the Gondwana.

  6. Hydrogeochemical characterization of groundwaters and porewaters beneath the Bruce nuclear site: evidence for diffusion-dominated transport in the Ordovician

    Energy Technology Data Exchange (ETDEWEB)

    Clark, I. [Univ. of Ottawa, Ottawa, ON (Canada); Al, T. [Univ. of New Brunswick, Fredericton, NB (Canada); Jensen, M.; Kennell, L. [Nuclear Waste Management Organization, Toronto, ON (Canada); Raven, K. [Geofirma Engineering Limited, Ottawa, ON (Canada)

    2011-07-01

    Investigations of the controls on solute transport in porewater and groundwater below the Bruce nuclear site involved laboratory-scale diffusion measurements, as well as measurements of natural tracer (δ{sup 18}O, δ{sup 2}H, {sup 87}Sr/{sup 86}Sr, Cl and Br) distributions and isotopic compositions of CH{sub 4}, CO{sub 2} and helium ({sup 3}He/{sup 4}He) in the porewaters and groundwaters. The analyses were performed on samples collected from drilled boreholes, DGR-1 through DGR-6, during site characterization activities and the results are summarized below. With the exception of just a few samples from the Upper Silurian, the effective diffusion coefficient (D {sub e}) values measured from DGR cores are all less than 10{sup -11} m{sup 2}/s, which is approximately one order of magnitude lower than measured De values from international programs in sedimentary rock. The majority of the data are in the range 10{sup -13} < D{sub e} < 10{sup -11} m{sup 2}/s, with Lower Silurian and Upper Ordovician shale samples representing the higher end of this range because of their relatively high porosity (7 to 9%). The low porosity of the Middle Ordovician limestone (< 2%) results in low D{sub e} values, clustering in the range 10{sup -13} < D{sub e} < 10{sup -12} m{sup 2}/s. The δ{sup 18}O, Cl, and Br profiles in the Middle Ordovician carbonates define trends of decreasing δ{sup 18}O values and tracer concentrations with depth, and are interpreted to result from an extremely long period of diffusion-dominated transport (~300 Ma). Near the base of the Middle Ordovician carbonates the δ{sup 2}H data display a slight enrichment, which could represent upward diffusion of deuterium-enriched water originating in the underlying Precambrian shield. A Precambrian shield influence on the Ordovician porewater chemistry is inferred from the measured {sup 87}Sr/{sup 86}Sr ratios in the Middle Ordovician carbonates, which are elevated above values expected for porewater in equilibrium

  7. Middle Ordovician Bioturbation Structures from Southeastern Margin of Ordos Basin and Their Environmentary Interpretation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Trace fossils were discovered in the Middle Ordovician Badou Member of Fengfeng Formation and the Member 1 of Jinsushan Formation in Mt. Jinsu of the Fuping region which lies at the southeastern margin of the Ordos basin. The rocks of the fore-mentioned parts contain a considerable amount of bioturbation structures, in which ichnogenus and ichnospecies can not be identified, and abundant stromatolites.The distributions and characteristics of the bioturbation structures are analyzed and summarized in this paper. The paleoenvironments of related formations and members were interpreted in the method of semiquantitative analysis of bioturbation structures with researches on stromatolites and sedimentology. It is suggested that Fuping zone, located in the southeastern margin of the Ordos basin, was a carbonate platform where stromatolite-developing tidal flat and low-energy subtidal open platform environments dominated. Also that this zone experienced three paleogeographic evolutions from tidal flat to low-energy subtidal open platform environments, that is, three larger-scale eustatisms occurred during the sedimentary period of Middle Ordovician Badou Member of Fengfeng Formation to the Member 1 of Jinsushan Formation.

  8. Platystrophia (Orthida and new related Ordovician and Early Silurian brachiopod genera

    Directory of Open Access Journals (Sweden)

    Harper, David A. T.

    2007-03-01

    Full Text Available More than 150 Ordovician and Early Silurian brachiopod species have been assigned to the genus Platystrophia King, 1850 mainly on the basis of their Spirifer-like shell exteriors. King’s concept of the genus was based on Platystrophia biforata King, which is not conspecific with Terebratulites biforatus Schlotheim, traditionally regarded as the type species of Platystrophia. Porambonites costatus Pander, 1830 is formally proposed as the type species of the genus to replace P. biforata; the latter is considered to be a nomen dubium. In our revised diagnosis, Platystrophia is restricted to a group of Arenig to upper Caradoc species from Baltica and Avalonia, whereas the Ashgill and lower Silurian taxa of these regions, hitherto assigned to Platystrophia, are placed in the new genus Neoplatystrophia. Platystrophia ponderosa Foerste, 1909 from the Upper Ordovician of North America is proposed as the type species of a new genus Vinlandostrophia. Two new species, Platystrophia baltica and Platystrophia pogrebovi from the Llanvirn–Caradoc of the East Baltic are also described.

  9. Influence of Ordovician carbonate reservoir beds in Tarim Basin by faulting

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The quality of the Ordovician carbonate reservoir beds in the Tarim Basin is closely related to the development of secondary pores,fractures and cavities. Karstification is important in improving the properties of reservoir beds,and karstification related to unconformity has caught wide attention. Compared with the recent research on the unconformity karst reservoir bed improvement,this paper shows a new way of carbonate reservoir bed transformation. Based on field survey,core and slices observation,transformation of Ordovician carbonate reservoir beds by faulting can be classified into three types: (1) Secondary faults and fracturs generated by faulting improved carbonate reservoir bed properties,which were named the Lunnan or Tazhong82 model; (2) upflow of deep geothermal fluids caused by faulting,with some components metasomatizing with carbonate and forming some secon-dary deposit,such as fluorite. It can improve carbonate reservoir bed properties obviously and is named the Tazhong 82 model; and (3) the faulting extending up to the surface increased the depth of supergene karstification and the thickness of reservoir bed. It is named the Hetianhe model. Trans-formation effect of carbonate reservoir beds by faulting was very significant,mainly distributed on the slopes or on the edge or plunging end of the uplift.

  10. The significance of 24-norcholestanes, triaromatic steroids and dinosteroids in oils and Cambrian-Ordovician source rocks from the cratonic region of the Tarim Basin, NW China

    Science.gov (United States)

    Li, Meijun; Wang, T.-G.; Lillis, Paul G.; Wang, Chunjiang; Shi, Shengbao

    2012-01-01

    Two oil families in Ordovician reservoirs from the cratonic region of the Tarim Basin are distinguished by the distribution of regular steranes, triaromatic steroids, norcholestanes and dinosteroids. Oils with relatively lower contents of C28 regular steranes, C26 20S, C26 20R + C27 20S and C27 20R regular triaromatic steroids, dinosteranes, 24-norcholestanes and triaromatic dinosteroids originated from Middle–Upper Ordovician source rocks. In contrast, oils with abnormally high abundances of the above compounds are derived from Cambrian and Lower Ordovician source rocks. Only a few oils have previously been reported to be of Cambrian and Lower Ordovician origin, especially in the east region of the Tarim Basin. This study further reports the discovery of oil accumulations of Cambrian and Lower Ordovician origin in the Tabei and Tazhong Uplifts, which indicates a potential for further discoveries involving Cambrian and Lower Ordovician sourced oils in the Tarim Basin. Dinosteroids in petroleum and ancient sediments are generally thought to be biomarkers for dinoflagellates and 24-norcholestanes for dinoflagellates and diatoms. Therefore, the abnormally high abundance of these compounds in extracts from the organic-rich sediments in the Cambrian and Lower Ordovician and related oils in the cratonic region of the Tarim Basin suggests that phytoplankton algae related to dinoflagellates have appeared and might have flourished in the Tarim Basin during the Cambrian Period. Steroids with less common structural configurations are underutilized and can expand understanding of the early development history of organisms, as well as define petroleum systems.

  11. The Environmental Context of Gastropods on Western Laurentia (Basin and Range Province) during the Great Ordovician Biodiversification Event

    Science.gov (United States)

    Dahl, Robyn Mieko

    2015-01-01

    Gastropods are a major component of modern marine ecosystems and can be found in nearly every type of marine ecosystem. They experienced their first notable radiation during the Great Ordovician Biodiversification Event (~470 Ma), during which their diversity tripled. This study examines the gastropod assemblage preserved in the Basin and Range…

  12. Rare finds of the coiled cephalopod Discoceras from the Upper Ordovician of Bornholm, Denmark

    DEFF Research Database (Denmark)

    Rasmussen, Jan Audun; Surlyk, Finn

    2012-01-01

    n. sp. and D. vasegaardense n. sp., occur in shales of the Upper Ordovician Lindegård Formation. The nautiloids are preserved as external molds in laminated siliciclastic mudstones. The very rare occurrence of cephalopods, combined with the apparently endemic nature of the Discoceras fauna, may...

  13. The roles of Lazarus taxa and refugia through the Ordovician-Silurian transition: data from the Brachiopoda

    Science.gov (United States)

    Rong, J.-Y.; Boucot, A. J.; Harper, D. A.; Zhan, R.-B.; Neuman, R. B.

    2003-04-01

    Global analyses of nearly 90 families and 275 genera of brachiopods from the middle Ashgill through the Hirnantian (Ordovician) to the lower-middle Rhuddanian (Silurian) suggest that about 60% and 40% of the total number of genera were eliminated at the first and second phases of the end Ordovician extinction event, respectively. Among the 85 surviving genera, about 50 with declining and 10 with proliferating abundances are known from the Hirnantian together with about 20 provisional Lazarus taxa. The Lazarus taxa are essentially survivors and form the extremity of the declining genera. The distributions of declining genera and relicts during the crisis interval shows a random and sporadic pattern, suggesting there was no single, common refugium for end Ordovician brachiopods. In addition to their biological attributes, a markedly decreased population size together with taphonomic failure and poor preservation, and collecting bias have contributed towards the distributional trends apparent during the event. The development of declining genera during the extinction may be linked to their palaeogeographical setting, the phylogenetic history of the taxa, and the ambient environmental conditions. This new global database has significantly reduced the number of Lazarus taxa and minimizes the number of possible locations for collective refugia during the end Ordovician crisis. Nevertheless, the atrypids, athyridids, pentamerids, and spiriferids had more limited distributions during the crisis interval but formed the locus for a Silurian diversification of the phylum into carbonate environments possibly around the Rhuddanian-Aeronian boundary.

  14. The anatomy, taphonomy, taxonomy and systematic affinity of Markuelia: Early Cambrian to Early Ordovician scalidophorans

    Science.gov (United States)

    Dong, X.-P.; Bengtson, S.; Gostling, N.J.; Cunningham, J.A.; Harvey, T.H.P.; Kouchinsky, A.; Val'Kov, A.K.; Repetski, J.E.; Stampanoni, M.; Marone, F.; Donoghue, P.C.J.

    2010-01-01

    Markuelia is a vermiform, annulated introvertan animal known as embryonic fossils from the Lower Cambrian to Lower Ordovician. Analysis of an expanded and revised dataset for Introverta shows that the precise position of Markuelia within this clade is dependent on the taxa included. As a result, Markuelia is assigned to the scalidophoran total group to reflect uncertainty as to whether it is a stem-scalidophoran or a stem-priapulid. The taxonomy of the genus is revised to provide an improved taxonomic framework for material assigned to Markuelia. Five species are recognized: M. secunda Val'kov, M. hunanensis Dong and Donoghue, M. lauriei Haug et al., M. spinulifera sp. nov. and M. waloszeki sp. nov. Finally, the preservation of Markuelia is evaluated in the light of both the taphonomy of the fossil embryos themselves and the experimental taphonomy of the priapulid Priapulus caudatus, which has been proposed as both a close relative and an anatomical analogue of Markuelia. ?? The Palaeontological Association.

  15. Tectonic overprint on magnetic fabric of the Ordovician Thetford Mines Ophiolite (Canada)

    Science.gov (United States)

    Di Chiara, Anita; Morris, Antony; Anderson, Mark W.; Menegon, Luca

    2017-04-01

    Studies in modern oceanic settings suggest locally along low-spreading ridges both lower crust and upper mantle peridotites may be exhumed to the seafloor in features known as oceanic core complexes (OCC). Examples of OCC on geological record can be preserved in ophiolites, relict of oceanic crust obducted onto continental margins, as for example the Jurassic Mirdita Ophiolite (Albania), suggesting that this spreading mode was active in the past. In order to understand such dynamics further, we investigated the OCC preserved in the Thetford Mines Ophiolite (TMO). TMO is part of the Southern Quebec ophiolites in the Canadian Appalachians (Quebec region), divided into three lithotectonic assemblages: The Humber Zone, a remnant of the Laurentian continental margin; The Cambrian-Ordovician Dunnage Zone, a remnant of the Iapetus Ocean and including the TMO and other ophiolites; and Silurian-Devonian Gaspé Belt, the sedimentary cover sequence. These were subjected to polyphase deformation, experiencing two Paleozoic orogenies: The Ordovician Taconian Orogeny (the Humber and Dunnage zones were amalgamated) and the Devonian Acadian orogeny which deformed and metamorphosed both the Dunnage Zone and the overlying Gaspe Belt. Here we present results from 12 paleomagnetic sites sampled on Humber zone on pillow lavas, dykes, layered gabbros and serpentinized dunites. Our results from AMS experiments show that these rocks, formed by fundamentally different magmatic processes, share a common magnetic fabric, with a kmin axis NW-SE orientated and the kmax steeply plunging to the NE. Additional processing of acquired BSE images and chemical mapping analyses at the SEM show that the kmax of the magnetic fabric is parallel to the elongation of magnetic particles (Iron rich minerals). This remarkably consistent fabric has a tectonic origin and is consistent with shortening perpendicular to the regional trend of fold axes.

  16. The Lawn Hill annulus: An Ordovician meteorite impact into water-saturated dolomite

    Science.gov (United States)

    Darlington, Vicki; Blenkinsop, Tom; Dirks, Paul; Salisbury, Jess; Tomkins, Andrew

    2016-12-01

    The Lawn Hill Impact Structure (LHIS) is located 250 km N of Mt Isa in NW Queensland, Australia, and is marked by a highly deformed dolomite annulus with an outer diameter of 18 km, overlying low metamorphic grade siltstone, sandstone, and shale, along the NE margin of the Georgina Basin. This study provides detailed field observations from sections of the Lawn Hill annulus and adjacent areas that demonstrate a clear link between the deformation of the dolomite and the Lawn Hill impact. 40Ar-39Ar dating of impact-related melt particles provides a time of impact in the Ordovician (472 ± 8 Ma) when the Georgina Basin was an active depocenter. The timing and stratigraphic thickness of the dolomite sequence in the annulus suggest that there was possibly up to 300 m of additional sedimentary rocks on top of the currently exposed Thorntonia Limestone at the time of impact. The exposed annulus is remarkably well preserved, with preservation attributed to postimpact sedimentation. The LHIS has an atypical crater morphology with no central uplift. The heterogeneous target materials at Lawn Hill were probably low-strength, porous, and water-saturated, with all three properties affecting the crater morphology. The water-saturated nature of the carbonate unit at the time of impact is thought to have influenced the highly brecciated nature of the annulus, and restricted melt production. The impact timing raises the possibility that the Lawn Hill structure may be a member of a group of impacts resulting from an asteroid breakup that occurred in the mid-Ordovician (470 ± 6 Ma).

  17. Ordovician gas exploration breakthrough in the Gucheng lower uplift of the Tarim Basin and its enlightenment

    Directory of Open Access Journals (Sweden)

    Wang Zhaoming

    2014-10-01

    Full Text Available A steady high yield natural gas flow was tapped in the Ordovician strata of Well Gucheng 6 drilled in the Gucheng lower uplift in the Tarim Basin in 2012, marking the discovery of another carbonate gas exploration field after the other two fields in the middle and northern Tarim Basin (the so called Tazhong and Tabei in the industry. The exploration in the Gucheng lower uplift has experienced three stages: the first stage, marine facies clastic exploration from 1995 to 2003, focusing on the Devonian Donghe sandstone lithologic traps, the Silurian overlapping lithologic traps, and the Upper Ordovician shelf slope turbidites; the second stage focusing on the reef shoal carbonate reservoirs from 2003 to 2006, during which oil and gas were first discovered in Well Gucheng 4; the third stage can be divided into two periods, in the first period, deeper insight into interbed karstification reservoir exploration, intense research on tricky seismic issues, selection of favorable zones, and 3D seismic deployment in advance laid a robust foundation for breakthroughs in oil and gas exploration; and during 2009–2012, through an in-depth investigation, Well Gucheng 6 was drilled, bringing about the major breakthrough in oil and gas exploration in this study area. This success proves that the Lower Paleozoic carbonate rocks in the Gucheng area have good geological conditions and broad prospect for oil and gas exploration, which give us enlightenment in three aspects: a. new insight into geologic understanding is the prerequisite of exploration breakthrough; b. addressing bottleneck technologies, and acquiring 3D seismic data are the guarantees of exploration breakthrough; and c. emancipation of mind and persistent exploration are key to the findings in new domains.

  18. Biostratigraphy and chronostratigraphy of the Cambrian-Ordovician great American carbonate bank

    Science.gov (United States)

    Taylor, John F.; Repetski, John E.; Loch, James D.; Leslie, Stephen A.

    2012-01-01

    The carbonate strata of the great American carbonate bank (GACB) have been subdivided and correlated with ever-increasing precision and accuracy during the past half century through use of the dominant organisms that evolved on the Laurentian platform through the Cambrian and the Ordovician. Trilobites and conodonts remain the primary groups used for this purpose, although brachiopods, both calcareous and phosphatic, and graptolites are very important in certain facies and intervals. A series of charts show the chronostratigraphic units (series and stages) currently in use for deposits of the GACB and the biostratigraphic units (zones, subzones, and biomeres) whose boundaries delineate them. Older and, in some cases obsolete, stages and faunal units are included in the figures to allow users to relate information from previous publications and/or industry databases to modern units. This chapter also provides a brief discussion on the use of biostratigraphy in the recognition and interregional correlation of supersequence boundaries within the Sauk and Tippecanoe megasequences, and the varied perspectives on the nature of biostratigraphic units and their defining taxa during the past half century. Also included are a concise update on the biomere concept, and an explanation of the biostratigraphic consequences of a profound change in the dynamics of extinction and replacement that occurred on the GACB in the Early Ordovician when the factors responsible for platformwide biomere-type extinctions faded and ultimately disappeared. A final section addresses recent and pending refinements in the genus and species taxonomy of biostratigraphically significant fossil groups, the potential they hold for greatly improved correlation, and the obstacles to be overcome for that potential to be realized.

  19. Strontium Isotope Composition and Characteristic Analysis of Cambrian-Ordovician Carbonate in the Region of Tazhong, Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    Huang Wenhui; Yang Min; Yu Bingsong; Fan Tailiang; Chu Guangzhen; Wan Huan; Zhu Jingquan; Wang Xu; Wu Shiqiang

    2006-01-01

    The research on the trace elements of Ordovician carbonates plays an important part in the whole work on reservoir in Tazhong ( 塔中 ) area. This paper systematically studies the characteristics and sedimentary settings of Ordovician dolomites in Tazhong area, Tarim basin, and debates their enrichment of mechanisms and different element existing patterns. The study makes use of ICP-MS analysis technology to test the strontium and manganese content of 109 samples from four wells in the Tazhong area, Tarim basin and strontium isotope composition tests have also been done on 25 samples from wells Zhong-1 and Zhong-4 on VG354 solid isotope mass spectrograph. By means of analyzing contents of strontium andmanganese elements, doing research on the strontium isotope composition characteristics from wells Zhong-1 and Zhong-4 and comparing the results of strontium analysis to the global Ordovician marine carbonate and its evolution trend, in the combination of sedimentary facies characteristics of isolated wells in this area, we can come to the following cognitions: (1) The marine carbonate strontium isotope curve in the Tazhong area of Tarim basin is consistent to the global evolution trend which is overall descending with time, the direct reason of which is the evolution of paleogeographic environment.The Ordovician paleogeographic environment goes through restricted platform to open platform and then shallow marine shelf in Tazhong area, Tarim basin. Dolomitization is another subordinate reason and the inversion of fluid with high manganese can lead to heavy strontium; (2) The fact that the 87 Sr/86 Sr ratios of the Upper Ordovician in Tazhong area have an apparent mono-decline trend with the time going by,which is similar to the global strontium isotope ratio, is suggesting that the variation of the Upper Ordovician sea level is starting, the overall trend of which is the rising of the sea level; (3) Compared to the global seawater strontium ratios, the 87 Sr/86 Sr

  20. Geodatabase of the datasets used to represent the four aquifer subunits of the Cambrian-Ordovician aquifer system, Illinois, Iowa, Michigan, Minnesota, and Wisconsin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This geodatabase includes spatial datasets that represent the Cambrian-Ordovician aquifer system in the States of Wisconsin, Michigan, Minnesota, Iowa, and Illinois....

  1. Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA

    Directory of Open Access Journals (Sweden)

    Carlton E. Brett

    2015-02-01

    Full Text Available Limestone and shale facies of the Upper Ordovician Grant Lake Formation (Katian: Cincinnatian, Maysvillian are well exposed in the Cincinnati Arch region of southern Ohio and north-central Kentucky, USA. These rocks record a gradual change in lithofacies and biofacies along a gently northward-sloping ramp. This gradient spans very shallow, olive-gray, platy, laminated dolostones with sparse ostracodes in the south to offshore, nodular, phosphatic, brachiopod-rich limestones and marls in the north. This study uses facies analysis in outcrop to determine paleoenvironmental parameters, particularly those related to water depth (e.g., position of the photic zone and shoreline, relative degree of environmental energy. Within a tightly correlated stratigraphic interval (the Mount Auburn and Straight Creek members of the Grant Lake Formation and the Terrill Member of the Ashlock Formation, we document the occurrence of paleoenvironmental indicators, including desiccation cracks and light-depth indicators, such as red and green algal fossils and oncolites. This permitted recognition of a ramp with an average gradient of 10–20 cm water depth per horizontal kilometer. Thus, shallow subtidal (“lagoonal” deposits in the upramp portion fall within the 1.5–6 m depth range, cross-bedded grainstones representing shoal-type environments fall within the 6–18 m depth range and subtidal, shell-rich deposits in the downramp portion fall within the 20–30 m depth range. These estimates match interpretations of depth independently derived from faunal and sedimentologic evidence that previously suggested a gentle ramp gradient and contribute to ongoing and future high-resolution paleontologic and stratigraphic studies of the Cincinnati Arch region.

  2. Latest Cambrian-Early Ordovician rift-related magmatic activity in the Kouřim Unit, Bohemian Massif

    Science.gov (United States)

    Soejono, Igor; Machek, Matej; Sláma, Jiří; Janoušek, Vojtěch

    2017-04-01

    inherited from the source, represented most likely by recycled immature arc-related material (?metagraywackes). The real tectonic setting of this Late Cambrian magmatic activity seems rather indicated by the within-plate geochemistry of the metadiorite. These results bring further evidence for the presence of the Late Cambrian-Early Ordovician extensional event documented throughout the basement of the European Variscan Belt. Together with other occurrences of bimodal magmatism, as well as metamorphic and sedimentary record, indicate an important period of lithospheric thinning. This overall Early Palaeozoic rift-related architecture is often considered as a consequence of the Rheic Ocean opening.

  3. Carbon and strontium isotope variations and responses tosea-level fluctuations in the Ordovician of the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Abstract In the Ordovician, a carbonate platform system grading from the platformal interioreastwards to basin was developed in the Tazhong area of the Tarim Basin, and the study column islocated in the place where the paleoslope occurred. The isotope compositions of the carbonatesthere are thus considered as having reflected those of simultaneous sea waters in view of its goodconnection with the open seas. The carbon and strontium isotope compositions of the Ordoviciancarbonates in the Tazhong area are analyzed, and their relationships to the sea-level fluctuationsare discussed as well. Studies have revealed that the carbon isotope composition is related posi-tively with the sea-level fluctuations, whereas an opposing situation occurs to the strontium isotopevariation. Similar responses of carbon and strontium isotope compositions to the sea-level fluctua-tions are reported elsewhere in the world, suggesting that the Ordovician sea-level fluctuations ofthe Tarim Basin were of eustatic implication.

  4. A Darriwilian (Middle Ordovician bivalve-dominated molluscan fauna from the Stairway Sandstone, Amadeus Basin, central Australia

    Directory of Open Access Journals (Sweden)

    Kristian G. Jakobsen

    2016-12-01

    Full Text Available A bivalve-dominated molluscan fauna is described from the Darriwilian (Middle Ordovician Stairway Sandstone, Amadeus Basin, central Australia. The fauna comprises 16 species of bivalves and rostroconchs plus six gastropod species which are treated under open nomenclature. Two new bivalves, Sthenodonta paenesymmetrica sp. nov. and Modiolopsis pojetai sp. nov., are described. The relatively low-diverse molluscan fauna constitutes around 62% of the total benthic macrofauna. Approximately 75% of the molluscs comprise bivalves, especially nuculoids, which were biogeographically restricted to low latitudes during the Ordovician. The molluscan assemblage displays a very high degree of endemism at species level, though the bivalve Sthenodonta eastii also occurs in the Georgina Basin farther to the northeast. This indicates a possible marine connective seaway between the Georgina and Amadeus basins during the Darriwilian. Nuculites, Cyrtodonta, and Modiolopsis are cosmopolitan and previously reported from North China, Avalonia, and Southern Gondwana.

  5. Proposed Auxiliary Boundary Stratigraphic Section and Point (ASSP) for the base of the Ordovician System at Lawson Cove, Utah, USA

    Science.gov (United States)

    Miller, James F.; Evans, Kevin R.; Ethington, Raymond L.; Freeman, Rebecca; Loch, James D.; Repetski, John E.; Ripperdan, Robert; Taylor, John F.

    2016-01-01

    The Global boundary Stratotype Section and Point (GSSP) for the base of the Ordovician System is at the First Appearance Datum (FAD) of the conodont Iapetognathus fluctivagus at Green Point in Newfoundland, Canada. Strata there are typical graptolitic facies that were deposited near the base of the continental slope.We propose establishing an Auxiliary boundary Stratotype Section and Point (ASSP) at the FAD of I. fluctivagus at the Lawson Cove section in the Ibex area of Millard County, Utah, USA. There, strata consist of typical shelly facies limestones that were deposited on a tropical carbonate platform and contain abundant conodonts, trilobites, brachiopods, and other fossil groups. Cambrian and Ordovician strata in this area are ~5300m thick, with the Lawson Cove section spanning 243m in three overlapping segments. Six other measured and studied sections in the area show stratigraphic relationships similar to those at Lawson Cove. Faunas have been used to divide these strata into 14 conodont and 7 trilobite zonal units. The widespread olenid trilobite Jujuyaspis occurs ~90cm above the proposed boundary at Lawson Cove; this genus is generally regarded as earliest Ordovician. Rhynchonelliform and linguliform brachiopods are common to abundant and are useful for correlation. The FAD of Iapetognathus fluctivagus and occurrences of Jujuyaspis and the Lower Ordovician planktonic graptolite Anisograptus matanensis all occur within a 2.4m interval of strata at a nearby section. Non-biological correlation tools include a detailed sequence stratigraphic classification and a detailed carbon-isotope profile. Especially useful for correlation is a positive 13C excursion peak ~15cm below the proposed boundary horizon. All of these correlation tools form an integrated framework that makes the Lawson Cove section especially useful as an ASSP for global correlation of strata with faunas typical of shallow, warm-water, shelly facies.

  6. Early to Middle Ordovician back-arc basin in the southern Appalachian Blue Ridge: characteristics, extent, and tectonic significance

    Science.gov (United States)

    Tull, James; Holm-Denoma, Christopher S.; Barineau, Clinton I.

    2014-01-01

    Fault-dismembered segments of a distinctive, extensive, highly allochthonous, and tectonically significant Ordovician (ca. 480–460 Ma) basin, which contains suites of bimodal metavolcanic rocks, associated base metal deposits, and thick immature deep-water (turbiditic) metasediments, occur in parts of the southern Appalachian Talladega belt, eastern Blue Ridge, and Inner Piedmont of Alabama, Georgia, and North and South Carolina. The basin's predominantly metasedimentary strata display geochemical and isotopic evidence of a mixed provenance, including an adjacent active volcanic arc and a provenance of mica (clay)-rich sedimentary and felsic plutonic rocks consistent with Laurentian (Grenvillian) upper-crustal continental rocks and their passive-margin cover sequences. Geochemical characteristics of the subordinate intercalated bimodal metavolcanic rocks indicate formation in a suprasubduction environment, most likely a back-arc basin, whereas characteristics of metasedimentary units suggest deposition above Neoproterozoic rift and outer-margin lower Paleozoic slope and rise sediments within a marginal basin along Ordovician Laurentia's Iapetus margin. This tectonic setting indicates that southernmost Appalachian Ordovician orogenesis (Taconic orogeny) began as an extensional accretionary orogen along the outer margin of Laurentia, rather than in an exotic (non-Laurentian) arc collisional setting. B-type subduction polarity requires that the associated arc-trench system formed southeast of the palinspastic position of the back-arc basin. This scenario can explain several unique features of the southern Appalachian Taconic orogen, including: the palinspastic geographic ordering of key tectonic elements (i.e., back-arc, arc, etc.), and a lack of (1) an obducted arc sensu stricto on the Laurentian margin, (2) widespread Ordovician regional metamorphism, and (3) Taconic klippen to supply detritus to the Taconic foreland basin.

  7. Chronostratigraphy of the Trenton Group and Utica Shale, Pt. II: Stratigraphic correlations using Ordovician glasses in K-bentonites

    Energy Technology Data Exchange (ETDEWEB)

    Delano, J.W.; Tice, S. (State Univ. of New York, Albany, NY (United States). Dept. of Geological Sciences); Mitchell, C.E.; Goldman, D. (State Univ. of New York, Buffalo, NY (United States). Dept. of Geology); Samson, S.D. (Syracuse Univ., NY (United States). Dept. of Geology)

    1992-01-01

    Rhyolitic glasses in the form of pristine melt inclusions that occur within quartz phenocrysts are being used for the geochemical fingerprinting of Ordovician K-bentonites in the northern Appalachian Basin. These melt inclusions are samples of pre-eruptive magma that became trapped during phenocryst growth in the deep crustal magma chambers. Plinian eruptions led to quenching of the enclosed rhyolitic magma to form glass when the quartz phenocrysts were blasted into the atmosphere. Preservation of this Ordovician glass is due to its being hermetically sealed within a mineral (quartz) that is resistant to weathering and diagenetic alteration. Chemical compositions of glasses in four Ordovician K-bentonites from the Mohawk Valley of New York State have been acquired using high-precision, electron microprobe analyses. The elements Mg, Cl, Ca, Ti, and Fe are often diagnostic. The accompanying figure illustrates one combination of elements that is effective in distinguishing K-bentonites, which are not stratigraphically equivalent. These K-bentonites were selected to test competing chronostratigraphies of the northern Appalachian Basin and indicate problems with the model by Cisne et al.

  8. Effect of Faulting on Ordovician Carbonate Buried-Hill Reservoir Beds in Hetianhe Gas Field,Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    Lü Xiuxiang; Bai Zhongkai; Li Jianjiao; Wang Weiguang; Fu Hui; Wang Qinghua

    2008-01-01

    Ordovician carbonate buried-hill reservoir beds in the Hetianhe (和田河) gas field,located in the Mazhatage (玛扎塔格) structural belt on the southern margin of the Bachu (巴楚) faulted uplift,southwestern Tarim basin,were studied.Based on field survey,core and slice observation,the general characteristics of carbonate buried-hill reservoir beds and specifically Ordovician carbonate buried-hill reservoir beds in the Hetianhe gas field were discussed.The karst zone of the reservoir beds in Hetianhe gas field was divided into superficial karst zone,vertical infiltration karst zone,lower subsurface flow karst zone,and deep sluggish flow zone from top to bottom.The effects of faulting on Ordovician carbonate buried-hill reservoir beds in the Hetianhe gas field were obvious.The faulting intensified the karstification and increased the depth of denudation.Faulting and subsequent fracture growth modified the reservoir beds and improved the physical property and quality of the reservoir beds.Moreover,faulting enhanced the development of the dissolution holes and fractures and increased the thickness of the effective reservoir beds.Meanwhile,faulting made the high porosity-permeability carbonate belts,which created conditions for the hydrocarbon accumulation,develop near the fault zone.

  9. Comparison of iron isotope variations in modern and Ordovician siliceous Fe oxyhydroxide deposits

    Science.gov (United States)

    Moeller, Kirsten; Schoenberg, Ronny; Grenne, Tor; Thorseth, Ingunn H.; Drost, Kerstin; Pedersen, Rolf B.

    2014-02-01

    Formation pathways of ancient siliceous iron formations and related Fe isotopic fractionation are still not completely understood. Investigating these processes, however, is difficult as good modern analogues to ancient iron formations are scarce. Modern siliceous Fe oxyhydroxide deposits are found at marine hydrothermal vent sites, where they precipitate from diffuse, low temperature fluids along faults and fissures on the seafloor. These deposits exhibit textural and chemical features that are similar to some Phanerozoic iron formations, raising the question as to whether the latter could have precipitated from diffuse hydrothermal fluids rather than from hydrothermal plumes. In this study, we present the first data on modern Fe oxyhydroxide deposits from the Jan Mayen hydrothermal vent fields, Norwegian-Greenland Sea. The samples we investigated exhibited very low δ56Fe values between -2.09‰ and -0.66‰. Due to various degrees of partial oxidation, the Fe oxyhydroxides are with one exception either indistinguishable from low-temperature hydrothermal fluids from which they precipitated (-1.84‰ and -1.53‰ in δ56Fe) or are enriched in the heavy Fe isotopes. In addition, we investigated Fe isotope variations in Ordovician jasper beds from the Løkken ophiolite complex, Norway, which have been interpreted to represent diagenetic products of siliceous ferrihydrite precursors that precipitated in a hydrothermal plume, in order to compare different formation pathways of Fe oxyhydroxide deposits. Iron isotopes in the jasper samples have higher δ56Fe values (-0.38‰ to +0.89‰) relative to modern, high-temperature hydrothermal vent fluids (ca. -0.40‰ on average), supporting the fallout model. However, formation of the Ordovician jaspers by diffuse venting cannot be excluded, due to lithological differences of the subsurface of the two investigated vent systems. Our study shows that reliable interpretation of Fe isotope variations in modern and ancient marine

  10. Tectonic and regional metamorphic implications of the discovery of Middle Ordovician conodonts in cover rocks east of the Green Mountain massif, Vermont

    Science.gov (United States)

    Ratcliffe, N.M.; Harris, A.G.; Walsh, G.J.

    1999-01-01

    Middle Ordovician (late Arenigian - early Caradocian) conodonts were recovered from a dolostone lens in carbonaceous schist 30 m below the base of the Pinney Hollow Formation in the Eastern Cover sequence near West Bridgewater, Vermont. These are the first reported fossils from the metamorphic cover sequence rocks east of the Green Mountain, Berkshire, and Housatonic massifs of western New England. The conodonts are recrystallized, coated with graphitic matter, thermally altered to a color alteration index (CAI) of at least 5, and tectonically deformed. The faunule is nearly monospecific, consisting of abundant Periodon aculeatus Hadding? and rare Protopanderodus. The preponderance of Periodon and the absence of warm, shallow-water species characteristic of the North American Midcontinent Conodont Province suggest a slope or basin depositional setting. The conodont-bearing carbonaceous schist is traceable 3 km southeast to the Plymouth area, where it had been designated the uppermost member of the Plymouth Formation, previously regarded as Early Cambrian in age. The age and structural position of the carbonaceous schist above dolostones of the Plymouth Formation but below the Pinney Hollow Formation (upper Proterozoic and Lower Cambrian?) suggest that this unit may be correlative or time transgressive with the Ira Formation, which underlies the Taconic allochthons in the Vermont Valley. Such a correlation supports the concept of placing the western limit of the root zone of the Taconic allochthons beneath the Pinney Hollow Formation. An approximate absolute age assignment for the conodont-bearing rock is between 470 and 454 Ma. This suggests that dynamothermal metamorphism during the Taconian orogeny on the east flank of the Green Mountains was younger than early Caradocian, which is in accord with the middle Caradocian age of the Ira Formation west of the Green Mountain massif.

  11. Petroleum source rock evaluation of the Alum and Dictyonema Shales (Upper Cambrian-Lower Ordovician) in the Baltic Basin and Podlasie Depression (eastern Poland)

    Science.gov (United States)

    Kosakowski, Paweł; Kotarba, Maciej J.; Piestrzyński, Adam; Shogenova, Alla; Więcław, Dariusz

    2017-03-01

    We present geochemical characteristics of the Lower Palaeozoic shales deposited in the Baltic Basin and Podlasie Depression. In the study area, this strata are represented by the Upper Cambrian-Lower Ordovician Alum Shale recognized in southern Scandinavia and Polish offshore and a equivalent the Lower Tremadocian Dictyonema Shale from the northern Estonia and the Podlasie Depression in Poland. Geochemical analyses reveal that the Alum Shale and Dictyonema Shale present high contents of organic carbon. These deposits have the best source quality among the Lower Palaeozoic strata, and they are the best source rocks in the Baltic region. The bituminous shales complex has TOC contents up to ca. 22 wt%. The analysed rocks contain low-sulphur, oil-prone Type-II kerogen deposited in anoxic or sub-oxic conditions. The maturity of the Alum and Dictyonema Shales changes gradually, from the east and north-east to the west and south-west, i.e. in the direction of the Tornquist-Teisseyre Zone. Samples, located in the seashore of Estonia and in the Podlasie region, are immature and in the initial phase of "oil window". The mature shales were found in the central offshore part of the Polish Baltic Basin, and the late mature and overmature are located in the western part of the Baltic Basin. The Alum and Dictyonema Shales are characterized by a high grade of radioactive elements, especially uranium. The enrichment has a syngenetic or early diagenetic origin. The measured content of uranium reached up to 750 ppm and thorium up to 37 ppm.

  12. Petroleum source rock evaluation of the Alum and Dictyonema Shales (Upper Cambrian-Lower Ordovician) in the Baltic Basin and Podlasie Depression (eastern Poland)

    Science.gov (United States)

    Kosakowski, Paweł; Kotarba, Maciej J.; Piestrzyński, Adam; Shogenova, Alla; Więcław, Dariusz

    2016-05-01

    We present geochemical characteristics of the Lower Palaeozoic shales deposited in the Baltic Basin and Podlasie Depression. In the study area, this strata are represented by the Upper Cambrian-Lower Ordovician Alum Shale recognized in southern Scandinavia and Polish offshore and a equivalent the Lower Tremadocian Dictyonema Shale from the northern Estonia and the Podlasie Depression in Poland. Geochemical analyses reveal that the Alum Shale and Dictyonema Shale present high contents of organic carbon. These deposits have the best source quality among the Lower Palaeozoic strata, and they are the best source rocks in the Baltic region. The bituminous shales complex has TOC contents up to ca. 22 wt%. The analysed rocks contain low-sulphur, oil-prone Type-II kerogen deposited in anoxic or sub-oxic conditions. The maturity of the Alum and Dictyonema Shales changes gradually, from the east and north-east to the west and south-west, i.e. in the direction of the Tornquist-Teisseyre Zone. Samples, located in the seashore of Estonia and in the Podlasie region, are immature and in the initial phase of "oil window". The mature shales were found in the central offshore part of the Polish Baltic Basin, and the late mature and overmature are located in the western part of the Baltic Basin. The Alum and Dictyonema Shales are characterized by a high grade of radioactive elements, especially uranium. The enrichment has a syngenetic or early diagenetic origin. The measured content of uranium reached up to 750 ppm and thorium up to 37 ppm.

  13. Exploring Late Globalization

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    2016-01-01

    The purpose of this viewpoint paper is to motivate a program of research on late globalization, a program that could eventually lead to one or more significant theories of late globalization. The paper explores the phenomenon of late globalization as well as the idea of “late” by drawing on sparse...... literature on late globalization from sociocultural and economic perspectives. It illustrates in a vignette the character and features of late globalization observable in the withdrawal from foreign locations or deinternationalization of universities, as late globalizing entitis. The paper discusses...... the range of constructs around the core idea of late globalization, generating questions for future work in a late globalization research program....

  14. Proto-Pacific-margin source for the Ordovician turbidite submarine fan, Lachlan Orogen, southeast Australia: Geochemical constraints

    Science.gov (United States)

    Offler, R.; Fergusson, C. L.

    2016-04-01

    The Early Palaeozoic proto-Pacific Pacific margin of Gondwana was characterised by a huge turbidite submarine fan with abundant clastic detritus derived from unknown sources within Gondwana. These deposits are widespread in the Lachlan Orogen of southeast Australia and include the Ordovician Adaminaby Group. Here we show that the mudstones and sandstones of the Adaminaby Group have chemical compositions that indicate the detritus in them was derived from a felsic, continental source similar in composition to Post Archean Australian Shales (PAAS). Chondrite normalised REE patterns showing LREE enrichment, flat PAAS normalised patterns and elemental ratios La/Sc, Cr/Th, Cr/V, Th/Sc and Th/U, have been used to support this interpretation. The dominance of quartz, and to a lesser degree plagioclase and biotite in the sandstones, suggests that the source was mainly granodioritic to tonalitic in composition. Th/Yb and Ta/Yb ratios indicate that the source was probably calc-alkaline, continental and shoshonitic. In addition, the presence of detrital muscovite, low-grade metamorphic and felsic volcanic clasts, demonstrates that a low-grade metamorphic terrane and volcanic arc contributed to the detritus observed in the samples. The presence of well-rounded zircons and tourmalines, very high Zr contents, high Zr/Sc and higher Cr/V ratios in some samples particularly in the Shoalhaven River area, indicate that some of the detritus was recycled. SiO2 versus (Al2O3 + K2O + Na2O) plots suggest the source areas experienced conditions varying from humid/semi-humid to semi-arid. Textural features and weathering trends of samples from all locations follow a curved pathway on Al2O3 - (CaO* + Na2O) - K2O (ACNK) diagrams, and indicate that the clays formed from weathering had been K-metasomatised prior to penetrative deformation. Chemical indices of alteration (CIA) reveal that even the freshest sandstones are altered and others are moderately to strongly altered. Discrimination

  15. Origin and evolution of palaeokarst within the Lower Ordovician (Ibexian) Goodwin Formation (Pogonip Group)

    Institute of Scientific and Technical Information of China (English)

    Robert; J.; Kervin; Adam; D.; Woods

    2012-01-01

    Palaeokarst within the Lower to Middle Ordovician Goodwin Formation, Pogonip Group (upper Ibexian-lower Whiterockian) was examined in detail at Meiklejohn Peak, Nevada USA in order to determine its origin, evolution, and relationship to sea level change. Detailed outcrop and petrographic examination of dolostone breccias and host rock reveals that palaeokarst was formed and affected by two distinct cycles of sea level change. A relative transgression resulted in deposition of lagoonal, ooid shoal, and shallow subtidal facies as sea level rose. Exposure of the carbonate platform led to the formation of multiple phreatic caves below the water table, as well as the development of numerous vadose conduits from the downward percolation of meteoric waters. Vadose water flow through early cave-wall and cave-roof collapse breccias resulted in rounding of smaller breccias clasts via physical transport and corrosion, while subsidence of subsurface karst led to the formation of a palaeodoline at the exposure surface. A second relative transgression deposited lagoonal sediments over the older karst; subsequent re-exposure of the carbonate platform resulted in the development of small breccia pockets as well as grikes within the youngest lagoonal sediments, and may have led to further corrosion of the older, deeper subsurface karst. The distal location of the study area within the carbonate platform suggests karst formation was the result of a substantial drop in relative sea level; the presence of multiple generations of palaeokarst imply that at least two higher-frequency cycles of sea-level change overprint the larger regression.

  16. Statistically significant faunal differences among Middle Ordovician age, Chickamauga Group bryozoan bioherms, central Alabama

    Energy Technology Data Exchange (ETDEWEB)

    Crow, C.J.

    1985-01-01

    Middle Ordovician age Chickamauga Group carbonates crop out along the Birmingham and Murphrees Valley anticlines in central Alabama. The macrofossil contents on exposed surfaces of seven bioherms have been counted to determine their various paleontologic characteristics. Twelve groups of organisms are present in these bioherms. Dominant organisms include bryozoans, algae, brachiopods, sponges, pelmatozoans, stromatoporoids and corals. Minor accessory fauna include predators, scavengers and grazers such as gastropods, ostracods, trilobites, cephalopods and pelecypods. Vertical and horizontal niche zonation has been detected for some of the bioherm dwelling fauna. No one bioherm of those studied exhibits all 12 groups of organisms; rather, individual bioherms display various subsets of the total diversity. Statistical treatment (G-test) of the diversity data indicates a lack of statistical homogeneity of the bioherms, both within and between localities. Between-locality population heterogeneity can be ascribed to differences in biologic responses to such gross environmental factors as water depth and clarity, and energy levels. At any one locality, gross aspects of the paleoenvironments are assumed to have been more uniform. Significant differences among bioherms at any one locality may have resulted from patchy distribution of species populations, differential preservation and other factors.

  17. Regional hydrogeology of the Silurian and Ordovician sedimentary rock underlying Niagara Falls, Ontario, Canada

    Science.gov (United States)

    Novakowski, Kentner S.; Lapcevic, Patricia A.

    1988-12-01

    Due to concern over the potential for widespread groundwater contamination in the sedimentary rock underlying the Niagara Falls area, this study was done to investigate the hydrogeology of the Silurian and Ordovician stratigraphy underlying the Upper Niagara River and the Eastern Niagara Peninsula. Seven boreholes (up to 150 m deep) were drilled, instrumented with multiple packer casing, tested for permeability, sampled for inorganic and organic solutes and monitored for hydraulic head to provide data for a conceptual model of regional groundwater flow. Results show that there are at least three distinct groundwater flow regimes in the bedrock. The uppermost regime consists of fracture zones in the Guelph and Lockport Formations, within which hydraulic conductivity, hydraulic head measurements and geochemical analyses indicate active groundwater circulation primarily discharging towards the Niagara Gorge and Escarpment. Underlying the Lockport Formation are an overpressured (high hydraulic head) regime in the Clinton-Upper Cataract-Lower Queenston Formation and an underpressured (low hydraulic head) regime in the Lower Cataract-Upper Queenston Formation. In both regimes, geochemical analyses and permeability measurements indicate very old and saline groundwater which probably has undergone minimal migration since pre-Pleistocene time. The implication based on the study so far, is that potential groundwater contamination below the bottom of the Lockport Formation is probably not significant in the Niagara Falls area except adjacent to the Niagara Gorge where vertical permeability in the lower flow regimes may be enhanced.

  18. Cyclic sedimentation patterns in Middle Ordovician Trenton group in central Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    Gardiner, M.A.

    1984-12-01

    The carbonate facies of the Middle Ordovician Trenton Group show repetitive sequences of micrite, bioclastic limestone, and siliciclastic shale. Five repetitive patterns based on sedimentologic and paleontologic data are present (in ascending order): 1) biosparite, 2) intrabiosparite, 3) pelsparite, 4) micrite, 5) alternating micrite and shale. The biosparite is of peritidal origin and is overlain by a stromatolitic cap. The average sequence thickness is 30-40 cm (12-16 in.). The intrabiosparite is a fining-upward sequence that grades to pelsparite with a micrite cap (total thickness averages 16 cm or 6 in.). This sequence is indicative of intershoal or shoaling conditions. Overlying the intrabiosparite sequence in pelsparite grading into a micrite cap. The pelsparite averages 8 cm (3 in.) in thickness, and is of shallow sublittoral origin. Highly burrowed micrite (2-6 cm or 0.8-2.4 in. thick), with a hardground cap, indicates periodic exposure. The upper unit is a deeper, sublittoral sequence of alternating kerogenic micrite and siliciclastic shale, ranging in thickness from 20 to 90 cm (7.9 to 35.4 in.). This pattern indicates a deepening of the carbonate shelf into a deeper, anoxic basin below wave base. These sequences are a result of storm deposition as indicated by shell and intraclast lags, by fining-upward trends, and by abrupt contacts between individual sequences. The series of sequences is a result of the decreasing effects of these storms in the deeper water facies.

  19. The Ordovician acritarch genera Tranvikium and Ampullula: their relationship and taxonomy.

    Science.gov (United States)

    Uutela; Sarjeant

    2000-10-01

    A restudy of the Ordovician (Arenig-Llanvirn) acritarch taxa Tranvikium polygonale Tynni, 1982, and Ampullula suetica Righi, 1991, indicates that they represent extremes in a single morphological plexus. At one extreme are forms with a polar 'excystment' aperture (closed by an operculum or two opercular pieces) and a smaller opening (plugged or open) at the opposite pole; at the other are forms lacking a polar aperture but having, at the opposite pole, a tube open distally and plugged or open basally. New morphological terms for these structures are proposed. The genera and species are treated as synonyms and an emended diagnosis is given for Tranvikium polygonale, incorporating this whole morphological plexus. The possible purposes of the structures exhibited and the likely affinity of T. polygonale to various groups of algae are discussed. The emendation of Ampullula by Brocke (1997) is rejected and the genus Stelomorpha Yin, 1994 retained, with an emended diagnosis. The new combination Stelomorpha princeps (Brocke, 1997) Uutela and Sarjeant is proposed.

  20. 中国新疆北部奥陶—志留系岩石组合的古构造、古地理意义%Significance of Paleostructure and Paleogeography of Ordovician-Silurian Rock Associations in Northern Xinjiang,China

    Institute of Scientific and Technical Information of China (English)

    何国琦; 李茂松

    2001-01-01

    Traditional tectonic ideas are that the orogenic belts in the northern Xinjiang were formed mainly in the late Paleozoic.However,new data show that there is almost continuous early Paleozoic orogenic belt surrounding the Junggar Basin.The facts will change the traditional idea which only emphasizes the late Paleozoic orogenesis.According to the new data,authors reconstructed the early Paleozoic geologic evolution of the Northern Xinjiang.The Junggar and adjacent old lands began to breakup in the Sinian period.The ancient ocean between those old lands came up to the biggest size at early Ordovician.The inferential Junggar old land often situated below sea level in the period of cracking and spreading of the old land.The ancient ocean of the Northern Xinjiang began to shrink and the old continental margin became active margin in the late Ordovician.Then,convergence,collision and orogenesis were took place among the Junggar,Yili and Siberia old lands.The late Ordovician and early-middle Silurian forearc or back-arc foreland basins might develop on the side of earn Junggar old land of the early Paleozoic orogenic belts.%近年的研究结果表明,在准噶尔盆地周边地区存在有几乎连续分布的早古生代造山带,这个事实有可能改变历来只强调北疆晚古生代造山作用的传统认识。震旦纪是准噶尔及其相邻古陆裂解的开始阶段,经寒武纪至早奥陶世,古洋已发展到最大规模。在区域性古陆裂解和伸展的背景下,推测准噶尔古陆经常位于海平面以下。晚奥陶世北疆的古洋开始收缩,古陆缘区转化成活动陆缘,准噶尔古陆先后与伊犁古陆和西伯利亚古陆汇聚和碰撞造山,在这两条早古生代造山带的近准噶尔古陆一侧,可能发育晚奥陶世至早、中志留世的弧前或弧后盆地和前陆拗陷。

  1. 塔里木盆地和田河气田下奥陶统白云岩成因%Dolomite Origin of Lower Ordovician in Hetian River Gas Field, Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    杨威; 王清华

    2000-01-01

    塔里木盆地和田河气田是最近探明的大型碳酸盐岩气田,下奥陶统主要发育两类白云岩。下部为层状白云岩,以细晶为主,阴极发光呈紫红色和蓝紫色,有序度为0.57~0.68,Sr、Na含量低,碳氧同位素偏负,成岩深度约1500m;上部斑状灰质白云岩与层状白云岩相比,晶形较粗、以中晶为主,有序度较高、为0.85~0.90,Sr偏高、Na偏低,碳氧同位素更偏负,成岩深度约2000m。通过对上述特征综合研究,认为层状白云岩形成于早期浅埋藏海水-淡水混合环境,提出斑状灰质白云岩形成于晚期深埋藏压实流-淡水混合环境,总结了两种成因机理,建立了相关的白云石化模式。%The Hetian river gas field is a new and large gas field inMazatage fault belt of Tarim basin. Ordovician carbonate rock is principal production formation. Lower Ordovician is characterized by developed dolomitization which can greatly improve reservoir property. There are two types of dolomite in Lower Ordovician. The bedded dolomite is in lower part. Their features is fine-crystal, cathodolaminescence of violet-red and blue-violet, degree of order 0. 57~0.68, low Sr and Na content, and negative carbon oxygen isotope value, implying that the bedded dolomite was formed in environment of early shallow-buffed fresh water and seawater mixing. On the contrary the upper part patch calcareous dolomite is medium-crystal, degree of order 0.85~0.90, high-Sr content , low-Na content, and more negative value carbon oxygen isotope indicating that the patch dolomites was formed in environment of late deep-buried compaction flow and fresh water mixing. The bedded dolomite was formed in an environment of restricted platform, where water was confined and salinity was high. There was porous water of high salinity with high Mg/Ca in intergranular pore of orginal sediment. It has much higher carbon oxygen isotope value and trace element

  2. SHRIMP zircon U-Pb dating from K-bentonite in the top of Ordovician of Wangjiawan Section, Yichang, Hubei,China

    Institute of Scientific and Technical Information of China (English)

    HU YanHua; ZHOU JiBin; SONG Biao; LI Wei; SUN WeiDong

    2008-01-01

    The Global boundary Stratotype Section and Point (GSSP) for the base of the Hirnantian Stage (the latest stage of the Ordovician System) is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangjiawan North Section, which is the upper most "golden spike" of the Ordovician.However, this "golden spike" is lack of reliable geochronology data. This article gives a sensitive high resolution ion microprobe (SHRIMPII) zircon U-Pb dating for a K-bentonite sample from the Kuanyinchiao Bed in the Wangjiawan North Section. The age of the K-bentonite sample is 443.2+1.6 Ma, that is to say, the isotopic age of the uppermost of Hirnantian Stage, the point of Ordovician-Silurian boundary,should be near to, but slightly younger than 443.2±1.6 Ma. This age is identical to the Ordovician-Silurian boundary age 443.7±1.5 Ma as declared by International Commission on Stratigraphy (ICS). So, this research provides some good geochronlogical data for the Hirnantian Stage and the Ordovician-Silurian boundary as well as the global correlation.

  3. Relations between spatial distribution and sequence types of the Cambrian-Ordovician marine source rocks in Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Marine source rocks are considered to be mainly composed of the Cambrian-Ordovician deposit in Tarlm Basin. Based on the previous studies made by other researchers, the authors calculated the thickness and distribution scale of these Cambrian-Ordovician source rocks by integrating sequence stratigraphy with investigations on sedimentary environments, well-shooting demarcating and calibrating the thickness of unknown source rocks with the thickness of the known ones according to characteristics of the source rocks that have "double track" seismic lineup reflectance. The results showed that the distribution area of the Lower-Cambrian Yuertusi Fm. source rock in platform inner depressions, slopes and deep basins is much bigger than that of the Middle Cambrian evaporite-lagoon source rock. Moreover, the former is superior to the latter In terms of the source rock quality. Likewise,the Middle-Ordovician Heituao Fm. source rock in the slopes and deep basins has a much wider distribution and better quality than the Upper Ordovician, and its quality is also better than those of the Shaergan and Yinggan Fms. source rock within platforms as well as the lime-mud-mound source rock along the fringe of the Upper-Ordovician platform. Most good Lower-Cambrian source rocks of the Kalpin outcrop lie on the initial ingression surface or in the condensed member of the Type Ⅰ sequence.In this section, the source rock in Type Ⅱ is inferior to that in Type Ⅰ, even being far from an effective one (TOC: <0.5%). Likewise, the good Middle-Ordovician Heituao source rock also lies on the initial ingression surface or in the condensed member of the Type Ⅰ sequence, while the poor Yinggan source rock and the lime-mud-mound along the fringe of the platform develop all in the Type Ⅱ sequence. Under the condition of the same sea-level rising altitude and time, the Ingression displacement (S1) at the base border in Type lis larger than S2 in Type Ⅱ. Thus, the distribution of the source

  4. Reconstructing Cambro-Ordovician Seawater Composition using Clumped Isotope Paleothermometry on Calcitic and Phosphatic Brachiopods

    Science.gov (United States)

    Bergmann, K.; Robles, M.; Finnegan, S.; Hughes, N. C.; Eiler, J. M.; Fischer, W. W.

    2012-12-01

    A secular increase in δ18O values of marine fossils through early Phanerozoic time raises questions about the evolution of climate and the water cycle. This pattern suggests two end-member hypotheses 1) surface temperatures during early Paleozoic time were very warm, in excess of 40°C (tropical MAT), or 2) the isotopic composition of seawater increased by up to 7-8‰. It has been difficult to evaluate these hypotheses because the δ18O composition of fossils depends on both temperature and the δ18O of water. Furthermore, primary isotopic signatures can be overprinted by diagenetic processes that modify geological materials. This too could explain the decrease in δ18O values of marine fossils with age. Carbonate clumped isotope thermometry can constrain this problem by providing an independent measure of crystallization temperature and, when paired with classical δ18O paleothermometry, can determine the isotopic composition of the fluid the mineral last equilibrated with. Combined with traditional tools, this method has the potential to untangle primary isotopic signatures from diagenetic signals. We measured the isotopic ordering of CO3 groups (Δ47) substituted into the phosphate lattice of phosphatic brachiopods in Cambrian strata. Phosphatic fossils are generally less soluble than carbonates in surface and diagenetic environments, and so are hypothesized to provide a more robust record of primary growth conditions. They also provide an archive prior to the rise of thick shelled calcitic fossils during the Ordovician Radiation. Additionally, measurements of the δ18O of the CO3 groups can be compared with the δ18O of PO4 groups to test whether their mutual fractionation is consistent with primary growth and the apparent temperature recorded by carbonate clumped isotope measurements. We are constructing a phosphatic brachiopod calibration for carbonate clumped isotope thermometry, and Δ47 values of CO2 extracted from modern phosphatic brachiopods suggest

  5. Geochemistry of the Cambrian-Ordovician aquifer system in the northern Midwest, United States: D in Regional aquifer-system analysis

    Science.gov (United States)

    Siegel, D.I.

    1989-01-01

    Distributions of solutes in aquifers of Cambrian and Ordovician age were studied in Minnesota, Wisconsin, Iowa, Illinois, northwestern Indiana, and northern Missouri to determine the sources of solutes and the probable chemical mechanisms that control regional variations in water quality. This work is part of the Northern Midwest Regional Aquifer-System Analysis project, whose objective is to describe and model the regional hydrogeology of the Cambrian- Ordovician aquifer system in the study region. The data base used included more than 3,000 ground-water-quality analyses from all major aquifers, but especially from the St. Peter, Jordan, and Mount Simon Sandstones and their equivalents. Regional variations in the water chemistry of glacial drift and other sedimentary units that overlie the Cambrian-Ordovician aquifer system in recharge areas in Minnesota, Iowa, Wisconsin, and Illinois were also studied, but to a lesser degree.

  6. Hirnantian (latest Ordovician bio- and chemostratigraphy of the Stirnas-18 core, western Latvia

    Directory of Open Access Journals (Sweden)

    Hints, Linda

    2010-03-01

    Full Text Available Integrated study of the uppermost Ordovician Porkuni Stage in the Stirnas-18 core, western Latvia, has revealed one of the most complete Hirnantian successions in the eastern Baltic region. The interval is characterized by two shallowing upwards depositional sequences that correspond to the Kuldiga and Saldus formations. The whole-rock carbon stable isotope curve indicates a long rising segment of the Hirnantian carbon isotope excursion, with the highest peak in the upper part of the Kuldiga Formation. The bioclast carbon and oxygen curves fit well with the whole-rock carbon data. Micro- and macrofossil data enabled seven combined associations to be distinguished within the Hirnantian strata. The early Porkuni fauna of the Spinachitina taugourdeaui Biozone, with pre-Hirnantian affinities, is succeeded by an interval with a Hindella–Cliftonia brachiopod association, a specific polychaete fauna, the chitinozoan Conochitina scabra, and the conodont Noixodontus girardeauensis. The middle part of the Kuldiga Formation is characterized by a low-diversity Dalmanella testudinaria brachiopod association, high diversity of scolecodonts, and the occurrence of the chitinozoan Lagenochitina prussica. From the middle part of the Kuldiga Formation the youngest occurrence yet known of the conodont Amorphognathus ordovicicus is reported. Also typical of the Kuldiga Formation is the occurrence of the trilobite Mucronaspis mucronata. The uppermost Hirnantian Saldus Formation contains no shelly fauna, but yields redeposited conodonts and at least partly indigenous chitinozoans and scolecodonts. Palaeontological criteria and stable isotope data enable correlation of the Stirnas section with other Hirnantian successions in the Baltic region and elsewhere.

  7. Logging Evaluation of the Ordovician Carbonate Reservoir Beds in the Lungudong Region,Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    YANG Wenjing; XIAO Chengwen; LIU Luofu; QI Guangzhong; JIANG Zhenxue; YUAN Yunchun; WANG Weili; YANG Song

    2010-01-01

    In recent years,great progress has been made constantly in oil and gas exploration in the Lungudong region of the Tarim Basin.However,progress has been slow in the evaluation of its main oil-producing horizons-the Ordovician carbonate reservoir beds.Based on previous researches and on the various data such as drilling,geology and oil test,in combination with the interpretation of each single-well imaging and conventional logging data,and through analysis and comparison,the identification methods in imaging and conventional logging for four types of carbonate reservoir beds in this region are summarized in this paper.Calculation formulas for four reservoir bed parameters,i.e.shale content,porosity,permeability and oil saturation in this region are proposed;and reservoir beds in this region are divided into three levels (Ⅰ,Ⅱ and Ⅲ) by combining oil test data and logging data,The lower limits of the effective porosity of reservoir beds and the fracture porosity of effective reservoir beds are determined as 1.8% and 0.04%,respectively.The physical property parameters are calculated by conventional logging curves,and the most advantageous areas for reservoir development are predicted comprehensively.On the plane,the high-value zones of reservoir bed parameters are mainly concentrated in the N-S-trending strike-slip fault,the Sangtamu fault horst zone and near the LG38 well area;vertically,the reservoir bed parameters of the Yijianfang Formation are better than those of the Yingshan and Lianglitage formations.

  8. Conodont dating of the Middle Ordovician breccia cap-rock limestone on Osmussaar Island, northwestern Estonia

    Directory of Open Access Journals (Sweden)

    Johanna I. S. Mellgren

    2012-08-01

    Full Text Available Various mechanisms have hitherto been suggested to explain the formation of the Kundan (Middle Ordovician Osmussaar Breccia in northwestern Estonia. Following the recent discovery of L-chondritic chromite in these peculiar, sand-penetrated strata, it seems plausible that the breccia is impact-related. Herein, the conodont faunas of three thin limestone intervals overlying the breccia at Osmussaar Island have been investigated, with the aim of establishing the age of the event in terms of the Baltoscandian conodont-based biostratigraphical scheme. Based on the presence of Microzarkodina ozarkodella, the limestone directly overlying the breccia is assigned to the M. ozarkodella Subzone of the Lenodus (Eoplacognathus? pseudoplanus Zone. This is reinforced by means of a faunal shift between this sample interval and the subsequent one, which is directly comparable with a faunal shift in the Mäekalda section, mainland Estonia. The middle, orthoceratite-yielding interval is assigned to the uppermost L. (E.? pseudoplanus Zone (or, alternatively, the lowermost Eoplacognathus suecicus Zone, whereas the uppermost interval, an oolitic limestone, is referable to the E. foliaceus Subzone, corresponding to the lower part of the Lasnamägi Stage. These results support a connection between the Osmussaar event and the stratigraphic interval yielding abundant meteorites and/or high levels of L-type chromite in Sweden, as they both can be referred to the lower and/or middle part of the Kunda Stage. The minor difference in age between the first limestones deposited after the brecciation and the meteorite and L-chromite-yielding interval in Baltoscandia can be explained as caused by a period of non-deposition, seen as numerous hiatuses of various extent in the Kunda Stage in northwestern Estonia.

  9. Storm deposits (tempestites) in Ordovician cratonic carbonates (Arbuckle Group, south-central Oklahoma)

    Energy Technology Data Exchange (ETDEWEB)

    Goldhammer, R.K.; Elmore, R.D.

    1983-03-01

    The Early Ordovician Kindblade Formation (Arbuckle Group), exposed in the Arbuckle Mountains of south-central Oklahoma, is a shallow marine epicontinental carbonate sequence that contains numerous storm deposits. The storm deposits (tempestites) are of two types, proximal and distal; the latter dominates in terms of both number and aggregate thickness. Distal tempestites consist of a fining upward sequence, 5 to 50 cm (2 to 20 in.) thick, that overlies an eroded hardground or firmground. The sequence consists of a lag lithoclastic grainstone that grades up into a laminated peloidal grainstone and then into mudstone. Primary sedimentary features such as laminations, burrows, and allochems are truncated at the surfaces, and borings are filled with unsorted lithoclasts. The lithoclasts at the base of the sequence are bored, generally well rounded, discoid in shape, and consist of mudstone, peloidal packstone, and oolitic grainstone. The overlying mudstone is sparsely fossiliferous and bioturbated with burrows either selectively dolomitized or infilled with lithoclastric grainstone. Proximal tempestites consist of coarse lithoclastic flat pebble conglomerate beds approximately 1 m (3.25 ft) thick that are interbedded with ooid grainstone and overlie mudstone. The contact between the units is sharp and erosional. The lithoclasts are of variable composition and may be up to 20 cm (7.75 in.) in diameter. The two types of tempestites occur in crude cycles, which consist of distal deposits overlain by proximal tempestites and ooid grainstones. The abundance of the storm deposits in the section, approximately one every 20 cm (7.75 in.), indicates that hundreds of storm-induced events are recorded in the Kindblade Formation.

  10. The World's second oldest strophomenoid-dominated benthic assemblage in the first Dapingian (Middle Ordovician) brachiopod fauna identified from Iran

    Science.gov (United States)

    Popov, L. E.; Cocks, L. R. M.

    2017-06-01

    Rocks previously mapped as Devonian at Gerd-Kuh in the Eastern Alborz Mountains of Iran have yielded Middle Ordovician faunas including the brachiopods described here, the first rhynchonelliform brachiopods of Dapingian age ever described from Iran. The shells described are defined as a new Dirafinesquina Benthic Association, and which is the second oldest strophomenoid-dominated assemblage from anywhere in the World. There are six brachiopods, three of which are newly named as the strophomenoid Dirafinesquina antiqua sp. nov., the orthoid Zhanorthis gerdkuhensis gen. et sp. nov., and the porambonitoid Eoporambonites raziabadensis sp. nov.

  11. Vestiges of an Ordovician west-vergent thin-skinned Ocloyic thrust belt in the Argentine Precordillera, southern Central Andes

    Science.gov (United States)

    Thomas, William A.; Astini, Ricardo A.

    2007-08-01

    Collision of the down-going, Laurentia-derived Argentine Precordillera terrane with the Gondwanan margin drove the Ordovician Ocloyic orogeny, including subduction volcanism, metamorphism, and top-to-west shearing east of the Precordillera. In the Precordillera, above passive-margin carbonates (Lower Ordovician San Juan Limestone and older carbonates), a Middle to Upper Ordovician westward-prograding synorogenic clastic wedge of black shale (Gualcamayo Shale) and coarser clastic sediment (Las Vacas Conglomerate and Trapiche Formation) fills a peripheral foreland basin. New research has identified vestiges of a west-directed thin-skinned Ocloyic foreland thrust belt that has been fragmented by east-directed Andean thrusting. The El Corral thrust sheet, with hanging-wall detachment in the San Juan Limestone, extends over a west-directed footwall frontal ramp and extensive flat to low-angle footwall cutoff in the Gualcamayo and Las Vacas formations. Las Vacas conglomerates in the footwall include olistoliths (10-m scale) exclusively of San Juan Limestone and Gualcamayo Shale; the beds in some olistoliths are folded. The advancing El Corral thrust sheet successively supplied and overrode the stratigraphically restricted olistoliths. In the El Corral footwall, tight west-vergent folds and faults within an anticlinorium in the San Juan Limestone and Gualcamayo Shale suggest a deeper (unexposed) thrust fault, the Los Celestitos fault. West of the anticlinorium, easterly dip (restored to remove Andean deformation) beneath an angular unconformity between Las Vacas and Trapiche beds is consistent geometrically with the trailing limb of a west-vergent fault-propagation anticline in the hanging wall of the subsurface Los Celestitos fault. The same angular unconformity truncates the El Corral fault and hanging-wall strata. In the Trapiche Formation, contrasting sedimentary facies from sandy turbidites westward to limestone-clast megabeds and olistoliths suggest another frontal

  12. Storm deposits as graves in Early Life: the Fezouata Lagerstätte case (Lower Ordovician, Morocco)

    Science.gov (United States)

    Vaucher, Romain; Pittet, Bernard; Hormière, Hélène; Martin, Emmanuel L. O.; Lefebvre, Bertrand

    2016-04-01

    The Fezouata Shale (Early Ordovician, Morocco) is renowned in the palaeontological community for its Konservat-Lagerstätte (Tremadocian in age) that yielded thousands of exceptionally well-preserved fossils (EPF) from the Great Ordovician Biodiversification Event. Lower Ordovician deposits in the central Anti-Atlas Mountain (Zagora area) are expressed by the Fezouata Shale and the Zini Formation. They consist in ca. 900m of siltstones and sandstones deposited in an epicontinental sea at the periphery of the Gondwanaland. Sedimentologic field analysis and sequence analysis were achieved on ten stratigraphic sections in order to constrain the palaeoenvironmental context of the Fezouata Biota and to predict the location (geographically and stratigraphically) of new Lagerstätten. Sedimentary structures (cm- to m-scale symmetrical ripples) and geometries (lobe, lobe-channel) point to storm dominance on the sedimentation but peculiar sedimentary features suggest a tide modulation. Thus, a wave-dominated tide-modulated model of deposition recording proximal offshore to shoreface environments for the Fezouata Shale and shoreface to foreshore environments for the overlying Zini Fm is proposed. Layers yielding EPF are argillaceous siltstones (with wave ripples of cm-scale wavelength) always overlain by fine-grained sandstones (distal storm deposits, few cm-thick, several m-long, with cm- to dm-scale hummocky cross-stratifications). Fast burying by storm deposits appear to be of prime importance to initiate the exceptional preservation of the soft tissues of animals in the fossil record. According to the model of deposition it correspond to environments close to the storm weather wave base. Lower Ordovician succession was deposited during a 2nd order cycle, although 3rd and 4th order cycles were also identified. Encoding these different orders of sea level fluctuations giving a value of "1" for the deepest part of sequences (for each order) and a value of "0" for the

  13. Origins of natural gas and the main controlling factors of gas accumulation in the Middle Ordovician assemblages in Jingxi area, Ordos Basin

    Directory of Open Access Journals (Sweden)

    Xinshe Liu

    2016-05-01

    Full Text Available During the progressive exploration of the Jingbian Gas Field in the Ordos Basin, multiple gas-bearing regions have been discovered in the dolomite reservoirs in the Middle Ordovician assemblages of Lower Paleozoic in Jingxi area, but these gas-bearing regions and intervals are significantly different in terms of gas enrichment degrees. So far, however, the reasons for the difference have not been figured out. In this paper, the origin and source of natural gas in the Middle Ordovician assemblages in Jingxi area was investigated on the basis of geochemical data (e.g. natural gas composition and carbon isotope, and then the main factors controlling the gas accumulation were analyzed. It is shown that the natural gas in the Middle Ordovician assemblages in the Middle Ordovician assemblages in Jingxi area is similar to that in the Upper Ordovician assemblages and Upper Paleozoic reservoir in terms of genesis and sources, and they are mainly the Upper Paleozoic coaliferous gas with some oil-derived gas. Under the influence of hydrocarbon generation center of coal source rocks and the source–rock–reservoir contact relationship, the proportion of coaliferous gas increases areally from the north to the south and vertically from Ma55 sub-member of the Lower Ordovician Majiagou Fm. It is concluded that the natural gas enrichment degree is controlled by the gas charging capacity at the hydrocarbon-supplying windows. Second, the vertical migration and distribution of natural gas is dominated by the differences of Ma55−Ma510 transport pathways. And third, the lateral migration direction of natural gas and the range of gas accumulation are controlled by the superimposition relationship between structures and reservoirs.

  14. Late Accretion and the Late Veneer

    CERN Document Server

    Morbidelli, Alessandro

    2014-01-01

    The concept of Late Veneer has been introduced by the geochemical community to explain the abundance of highly siderophile elements in the Earth's mantle and their chondritic proportions relative to each other. However, in the complex scenario of Earth accretion, involving both planetesimal bombardment and giant impacts from chondritic and differentiated projectiles, it is not obvious what the "Late Veneer" actually corresponds to. In fact, the process of differentiation of the Earth was probably intermittent and there was presumably no well-defined transition between an earlier phase where all metal sunk into the core and a later phase in which the core was a closed entity separated from the mantle. In addition, the modellers of Earth accretion have introduced the concept of "Late Accretion", which refers to the material accreted by our planet after the Moon-forming event. Characterising Late Veneer, Late Accretion and the relationship between the two is the major goal of this chapter.

  15. Periodic anoxic shelf in the Early-Middle Ordovician transition: ichnosedimentologic evidence from west-central Utah, USA

    Institute of Scientific and Technical Information of China (English)

    GONG; Yiming

    2001-01-01

    [1]Fortey, R. A., Droser, M. L., Trilobites at the base of the Middle Ordovician, western United States, Journal of Paleontology. 1996. 70(1): 73-99.[2]Droser. M. L., Sheehan, P. M., Palaeoecology of the Ordovician radiation: Resolution of large scale patterns with individual clade histories, palaeogeography and environments, Geobios, 1997, 20:221-229.[3]Li, X., Droser, M. L., Lower and Middle Ordovician shell beds from the Basin and Range Province of the western United States (California, Nevada, and Utah), Palaios, 1999, 14: 215-233.[4]Miller. J. F., Loch, J. D., Stitt, J. H. et al., Origins of the great Ordovician biodiversification: the record at Lawson Cove, Ibex area, Utah, USA, Acta Universitatis Carolinae-Geologica, 1999, 43( 1/2): 459-462.[5]Tolmacheva, T. Y., Holmer, L. E., Dronov, A. et al., Early Ordovician (Hunneberg-Volkhov) facial and faunal changes in the east Baltic, Acta Universitatis Carolinae-Geologica, 1999, 43(1/2): 467-470.[6]Sprinkle, J., Guensgurg, T. E., Rozhnov, S. V., Correlation anomaly shown by Ordovician shelly and trace fossils in Baltic Russia: redating the Ordovician radiation, Acta Universitatis Carolinae-Geologica, 1999, 43(1/2): 471-474.[7]Carrera, M. G.. Sanchez, T M., Benedetto, J. L., Paleoenvironmental controls on biofacies in the early Ordovician limestones of the Argentine Precordillera, Acta Universitatis Carolinae-Geologica, 1999, 43(1/2): 475-477.[8]Sepkoski. J. J. Jr., A factor analytic description of the Phanerozoic marine fossil record, Paleobiology, 1981, 7: 36-53.[9]Sepkoski, J. J. Jr., The Ordovician radiations: Diversification and extinction shown by global genus-level taxonomic data,in Ordovician Odyssey: Short Papers of the Seventh International Symposium on the Ordovician System (eds. Cooper, J. D.. Droser, M. L., Finney, S. C.), Fullerton, CA, Pacific Section, Society of Sedimentary Geology (SEPM), 1995, 78:393-396.[10]Hintze. L. F.. Lower Ordovician detailed

  16. Carbon and strontium isotope variations and responses tosea-level fluctuations in the Ordovician of the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    JIANG; Maosheng

    2001-01-01

    [1]Arthur, M. A., The carbon cycle-controls of atmospheric CO2 and climate in the geologic past, in Climate in Earth History (eds., Berger, W. M., Crowell, J. C), Washington D C: U. S. National Academy Press, 1982, 55-67.[2]Kroopnick, P. M., Margolis, M. V., Wong, C. S., δ18C variations in marine carbonate sediments as indicators of the CO2 balance between atmosphere and ocean, in The Fate of Fossil Fuel CO2 in the Ocean (eds., Anderson, N. R., Malahoff. A.),New York: Plenum Press, 1977, 295-321.[3]Veizer, J., Fritz, P., Jones, B., Geochemistry of brachiopods: Oxygen and carbon isotopic records of Paleozoic oceans,Geochim. Cosmochim. Acta, 1986, 50: 1679- 1696.[4]Wadleigh, M. A., Veizer, J., 18O/16O and 13C/12C in Lower Paleozoic articulate brachiopods: Implications for the isotopic composition seawater, Geochim. Cosmochim. Acta, 1992, 56:431-443.[5]Goldberg, E. D., Minor elements in sea water, in Chemical Oceanography (eds., Riley, J. P., Skirrow, G.), Vol. l, New York: Academic Press, 1986.[6]Fanre, G., Principles ofIsotope Geology, New York: Wiley, 1986, 1 -589.[7]Ebneth, S., Diener, A., Buhl, D. et al., Strontium isotope systematics of conodonts: Middle Devonian, Eifel Mts. Germany,Paleogeogr. Paleoclimatol. Paleoecol, 1996, 119:201 - 214.[8]Martin, E. E., Macdougall, J. D., Sr and Nd isotopes at Permian / Triassic boundary: A record of climate change, Chem.Geol.. 1995. 125: 73-79.[9]Jones. C. E.. Jenkyns, H. C., Hesselbo, S. P., Strotium isotopic variations in Jurassic and Cretaceous seawater, Geochemica et Cosmochemica Acta. 1994, 58:3061 - 3074.[10]McArthur. J. M., Kennedy, W. J., Chen, M. et al., Staontium isotope stratigraphy for Late Cretaceous time: Drect numerical clibration of the Sr curve based on the U.S. western interior, Paleogeogr. Paleoclimatol. Paleoecol., 1994, 108:95-119.[11]McArthur, J. M., Thirlwall, M. F., Gale, A. S. et al., Strotium isotope stratigraphy for the Late Cretaceous: A new curve

  17. Conodonts, stratigraphy, and relative sea-level changes of the tribes hill formation (lower ordovician, east-central New York)

    Science.gov (United States)

    Landing, E.D.; Westrop, S.R.; Knox, L.A.

    1996-01-01

    Tremadocian onlap is recorded by the Tribes Hill Formation. The formation is a lower Lower Ordovician (upper conodont Fauna B Interval(?)- Rossodus manitouensis Zone) depositional sequence that unconformably overlies the Upper Cambrian Little Falls Formation. Depositional environments and stratigraphy indicate that the Tribes Hill was deposited on a wave-, not tide-, dominated shelf and that a uniform, 'layer-cake' stratigraphy is present. The deepening-shoaling sequence of the Tribes Hill includes the: 1) Sprakers Member (new; peritidal carbonate and overlying tempestite limestone and shale); 2) Van Wie Member (new; subtidal shale and limestone); 3) Wolf Hollow Member (revised; massive carbonates with thrombolitic cap); and 4) Canyon Road Member (new; glauconitic limestone and overlying evaporitic dolostone). The shoaling half-cycle of the Tribes Hill is older than a shoaling event in western Newfoundland, and suggests epeirogenic factors in earliest Ordovician sea-level change in east Laurentia. Conodont and trilobite biofacies track lithofacies, and Rossodus manitouensis Zone conodonts and Bellefontia Biofacies trilobites appear in the distal, middle Tribes Hill Formation. Twenty-four conodont species are illustrated. Ansella? protoserrata new species, lapetognathus sprakersi new species, Leukorhinion ambonodes new genus and species, and Laurentoscandodus new genus are described.

  18. The hydrothermal karstification and its effect on Ordovician carbonate reservoir in Tazhong uplift of Tarim Basin, Northwest China

    Institute of Scientific and Technical Information of China (English)

    WU; MaoBing; WANG; Yi; ZHENG; MengLin; ZHANG; WeiBiao; LIU; ChunYan

    2007-01-01

    With a detailed study on petrology, mineralogy and geochemistry of some important Ordovician carbonate well core samples in Tazhong uplift of Tarim Basin, the distinguishing symbols of hydrothermal karstification are first put forward as the phenomena of rock hot depigmentation, hot cataclasm and the appearance of typical hydrothermal minerals such as fluorite, barite, pyrite, quartz and sphalerite. The main homogenization temperatures of primary fluid inclusions in fluorite are from 260 to 310℃, indicating the temperature of hydrothermal fluid. The fluid affected the dissolved rocks and showed typical geochemistry features with low contents of Na and Mg, and high contents of Fe, Mn and Si. The ratio of 3He/4He is 0.02Ra, indicating the fluid from the typical continental crust. The hydrothermal fluid karstification pattern may be described as follows: the hot fluid is from the Permian magma, containing dissolving ingredients of CO2 and H2S, and shifts along fault, ruptures and unconformity, and dissolves the surrounding carbonates while it flows. The mechanism of hydrothermal karstification is that the mixture of two or more fluids, which have different ion intensity and pH values, becomes a new unsaturated fluid to carbonates. The hydrothermal karstification is an important process to form hypo-dissolved pinholes in Ordovician carbonates of Tazhong uplift of Tarim Basin, and the forming of hydrothermal minerals also has favorable influence on carbonate reservoirs.

  19. Middle and Upper Ordovician conodonts of the Moscow Syneclise: New data on stratigraphy of the Borehole Gavrilov Yam-1 section

    Science.gov (United States)

    Tolmacheva, T. Yu.; Zaitsev, A. V.; Alekseev, A. S.

    2013-07-01

    On the basis of the first data on the taxonomic composition and stratigraphic distribution of conodont assemblages in the Borehole Gavrilov Yam-1 section (central part of the Moscow Syneclise), its biostratigraphic subdivision is proposed with specification of some formations previously substantiated by finds of acritarchs and benthic faunal assemblages. The Nefedovo Formation, which was previously attributed to the Volkhov Horizon (Dapingian Stage), is correlated by conodonts with the Kunda Horizon (basal part of the Darriwilian Stage). The middle part of the overlying Veksa Formation, which was formerly considered to be of Kunda age, yielded conodonts that mark the lower boundary of the Azeri Horizon. Conodonts found in the Mitino Formation with highly ambiguous age allow it to be correlated with the Jöhvi and Keila horizons of the Sandbian Stage (Upper Ordovician). The lower part of the Varlyga Formation, which is attributed to the Lower Silurian in the regional stratigraphic scale, is correlated by conodonts with the Oandu and Rakvere regional stages (lower part of the Katian Stage, Upper Ordovician). In total, 44 conodont species were found in 79 samples; most of them are illustrated. A brief description is given for representatives of the genera Pectinognathus, Phragmodus, and Semiacontiodus. The conodont assemblage includes species distributed in the northwestern part of the East European Platform (Baltoscandian paleobasin) and taxa characteristic of the Timan-Pechora region.

  20. Pore structure characteristics of the relative water-resisting layer on the top of the Ordovician in Longgu Coal Mine

    Institute of Scientific and Technical Information of China (English)

    Rong Huren; Bai Haibo⇑

    2014-01-01

    In order to study the permeability and water-resisting ability of the strata on the top of the Ordovician in Longgu Coal Mine, this paper tested the permeability and porosity of the strata, investigated the fracture and pore structure features of the strata, and identified the main channels which govern the permeability and water-resisting ability of the strata. The permeability of the upper, central and lower strata shows as 2.0504 ? 10?3-2.782762 ? 10?3, 4.1092 ? 10?3-7.3387 ? 10?3 and 2.0891 ? 10?3-3.2705 ? 10?3 lm2, respectively, and porosity of that is 0.6786-0.9197%, 0.3109-0.3951%and 0.9829-1.8655%, respectively. The results indicate that:(1) the main channels of the relative water-resisting layer are the pore throats with a diameter more than 6 lm;(2) the major proportion of pore throats in the vertical flow channel and the permeability first increases and then sharply decreases; (3) the fractures occurring from the top to 20 m in depth of the strata were filled and there occurred almost no fracture under the depth of 40 m;and (4) the ratio of turning point of the main flow channel in the strata on top of Ordovician can be used to confirm the thickness of filled water-resisting layers.

  1. Fenxiang biota: a new Early Ordovician shallow-water fauna with soft-part preservation from China.

    Science.gov (United States)

    Balinski, Andrzej; Sun, Yuanlin

    Our perception of biodiversity in the geological past is incomplete and biased because most organisms did not have mineralized skeletons and therefore had little chance of fossilization. This especially refers to shallow-water marine environments, rarely represented by localities with exceptional preservation of fossil material (known as taphonomic windows or Konservat-Lagerstätten). Such extraordinary "windows" may markedly broaden our knowledge of biodiversity of the past. Here, we show a review of the invertebrate fossils from recently discovered locality in the Lower Ordovician Fenxiang Formation of Hubei Province in southern China revealing exceptional preservation of soft tissues. The fauna, generally of shallow-water aspect, contains linguloid brachiopods with a remarkably preserved pedicle, the oldest traces of nematode life activities, the oldest reliable record of hydroids, the first fossil antipatharian corals, a pyritized colonial organism of unknown affinity, supposed arthropod appendages, probable phosphatized scalidophoran worm embryo and other fossils. Our discovery supports the opinion that the famous soft-bodied preservation of Burgess Shale- or Chengjiang-type did not vanish from the fossil record in post-Cambrian times. The new finding represents a prelude to the Great Ordovician Biodiversification Event and provides evidence for calibration of molecular clock of several invertebrate lineages.

  2. Hydrothermal recrystallization of the Lower Ordovician dolomite and its significance to reservoir in northern Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Discovered in S15 and some other wells, the Lower Ordovician in the northern Tarim Basin consists mainly of brown gray-dark gray very fine-fine crystalline dolomite, with a minor portion of locally light gray-white medium-coarse crystalline dolomite. Silicification can be observed in the medium-coarse dolomite, and some euhedral drusy quartz can also be found in pores and fractures of the dolomite. The homogenization temperature of the fluid inclusions in the medium-coarse dolomite is between 110 and 200°C with maximum between 140 and 190°C, and the salinity is between 10.7 and 18.5 wt.% NaCl Eq. The homogenization temperature and salinity of the fluid inclusions in the medium-coarse dolomite are similar to those in the drusy quartz. Compared with the very fine-fine dolomite, the medium-coarse phase contains relatively high Fe and Mn. The average concentration of FeO and MnO in the medium-coarse dolomite is 1.917% and 0.323%, respectively. The medium-coarse dolomite has a remarkable negative Eu anomaly, consistent with the REE pattern of the intermediate-felsic igneous rocks in the Tarim Basin. The oxygen isotopic composition of the medium-coarse dolomite is relatively lighter than that of the very fine-fine dolomite. The δ18OPDB values of the medium-coarse dolomite are between -10.35‰ and -7.31‰. The δ18OSMOW values of the fluid associated with the medium-coarse dolomite can be calculated according to homogenization temperature and oxygen isotope fractionation factor between dolomite and fluid, and the calculated values are between +4‰ and +10‰, consistent with those of the hydrothermal fluid. The medium-coarse dolomite has relatively high 87Sr/86Sr ratios as well, indi- cating an origin associated with intermediate-felsic igneous rock. The homogenization temperature, element composition, REE pattern, oxygen and strontium isotopes demonstrate that the medium-coarse dolomite is the result of recrystallization of very fine-fine dolomite under

  3. Late Yanshan-Himalayan hydrocarbon reservoir adjustment and hydrotherrnal fluid activity in the central Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The adjustment of primary hydrocarbon reservoirs in marine formations is an important feature of the oil pools in the Tarim Basin. Large-scale hydrocarbon adjustment is related to the strong regional tectonic movements, which is always accompanied by extensive migration of basin fluids including diagenetic and mineralizing fluids. Organic fluid inclusions are well developed in hydrothermal minerals, such as fluorite, which have been found in the dissolution-enlarged fractures or karstification caves in the Ordovician in the central Tarim Basin. Proved by well drilling, the fluorite deposit is good reservoir for oil and gas. So the peculiar accompanied or superimposed relationship between fluorite hydrothermal fluid mineralization and hydrocarbon migration and accumulation exists in the Ordovician in the central Tarim Basin. Considering regional tectonic setting and mineralization condition,through different kinds of analytic methods including electron spin resonance dating, fluid inclusion laser Raman and colonial inclusions hydrocarbon fossil analysis, we proposed that extensive mineralizing fluids and hydrocarbon migration occurred in late Yanshan-Himalayan (110.4-30.8 Ma) period, and Himalayan, especially, is an important period for hydrocarbon accumulation from 34.3 Ma to present.

  4. Vertical variation of trace elements and its relation to the water-bearing capacity of Ordovician strata,in Datun coal field

    Institute of Scientific and Technical Information of China (English)

    LIU Huai-zhong; HAN Bao-ping

    2009-01-01

    We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace elements is reported. The relationship of the variation to the water-beating capacity of the Ordovician strata is discussed. The minimum concentration of eleven (of 14 total) trace elements appears in the lower Majiagou formation. The maximum concentrations mainly appear in the Badou and Jiawang formations: eight maxima are located in Badou and four more are in Jiawang. The study of karst development and the water-bearing capacity of Ordovician strata shows that karst is well developed in the Majiagou formation and there is a consequent high water-beating capacity in this formation: Badou and Jiawang formations are contrary to this situation. The results illustrate that the minimum concentrations of most trace elements within certain Ordovician formations can be taken as strong evidence for the existence of a well developed karst and a high wa-ter-bearing capacity.

  5. Similar morphological and chemical variations of Gloeocapsomorpha prisca in Ordovician sediments and cultured Botryococcus braunii as a response to changes in salinity

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Derenne, S.; Metzger, P.; Largeau, C.; Bergen, P.F. van; Gatellier, J.P.; Leeuw, J.W. de; Berkaloff, C.

    1992-01-01

    Most Ordovician source rocks consist of accumulation of a colonial marine microorganism, Gloeocapsomorpha prisca (G. prisca) whose nature, ecology and affinity with extant organisms have been in dispute for years. Furthermore, recent studies have shown major differences in phenol moieties between tw

  6. Chitinozoan biostratigraphy and carbon isotope stratigraphy from the Upper Ordovician Skogerholmen Formation in the Oslo Region. A new perspective for the Hirnantian lower boundary in Baltica

    DEFF Research Database (Denmark)

    Amberg, Chloé E. A.; Vandenbroucke, Thijs R. A.; Nielsen, Arne Thorshøj

    2017-01-01

    The end-Ordovician has received wide attention because it hosts major global events including mass extinctions, glaciations, significant sea-level fluctuations, and large-scale perturbations of the Earth's carbon cycle. Knowing the order and timing of these events and their components is crucial ...

  7. Discovery of effective scale source rocks of the Ordovician Majiagou Fm in the Ordos Basin and its geological significance

    Directory of Open Access Journals (Sweden)

    Jianqi Tu

    2016-10-01

    Full Text Available There have been different views on the origins of gas reservoirs of Ordovician Majiagou Fm in the Ordos Basin, but none of them supports the opinion that there are scale source rocks (TOC>0.5% in the Majiagou Fm. In this paper, a series of analysis was made on cores and cutting samples taken from recent newly-drilled wells in the Ordovician reservoirs in the central–eastern areas of the Ordos Basin. Accordingly, the organic abundance features of different types of source rocks in the Majiagou Fm were presented, and for the first time, it was discovered and verified that there are effective scale source rocks with high organic abundance. Based on these analysis and studies, the following results were achieved. First, the effective source rocks of Majiagou Fm are composed of thin–thick layered dark dolomite-bearing mudstones, dolomitic mudstones and argillaceous dolomites, and their enrichment and distribution are obviously controlled by sedimentary facies. During the sedimentation of Majiagou Fm, the effective scale source rocks developed better at the regressive stage than at the transgressive stage. The effective source rocks are primarily distributed in the upper part of Ma 5 Member (especially concentrated in the third and fourth sub-members and secondly in Ma 3 Member, Ma 1 Member and the middle–lower part of Ma 5 Member. Second, the effective source rocks are areally distributed in a dual-girdle form around the Mizhi Salt Depression, and those in the secondary depressions are medium–thick layered, with a large total thickness and high organic abundance. Third, the effective source rocks in the center of Mizhi Depression and the secondary uplifts are thin-layered, with a small total thickness and low organic abundance. And fourth, the organic abundance of the effective source rocks varies from 0.30% to 8.45%. Phytoplankton and Acritarchs are the main parent materials of hydrocarbon, and organic matters are of sapropel or sapropel

  8. 塔里木盆地塔中地区奥陶系碳酸盐岩封盖性能%Sealing capacity of the Ordovician carbonate rocks in Tazhong area,the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    钱一雄; 何治亮; 陈强路; 李慧莉; 路清华; 蔡习尧; 尤东华

    2012-01-01

    利用5口区探井碳酸盐岩的矿物组成、微孔特征和测井资料等对塔里木盆地塔中地区奥陶系碳酸盐岩封盖性能进行了研究.结果表明,塔中奥陶系良里塔格组和鹰山组位于中成岩A-B亚段和晚成岩A亚段.良里塔格组中颗粒灰岩的突破压力为1.81 ~ 29.76 MPa,突破半径为13.89~77.35 nm,变化较大;泥灰岩的突破压力为14.33 MPa,突破半径为9.77 nm;含泥质条带泥晶灰岩的突破压力为3.15 ~5.41 MPa,突破半径为25.90~44.51 nm.鹰山组灰云岩的突破压力为0.98 ~ 10.35 MPa,突破半径为13.52~142.60 nm.因此,良里塔格组泥灰岩、部分颗粒灰岩及鹰山组云灰岩均有一定的封盖能力,其连续厚度大于5 m,突破压力大于5 MPa,突破半径介于10 ~ 20 nm,孔喉半径小于0.1 μm.塔中鹰山组内分布稳定、厚4~10m的高电阻含云灰岩构成的致密层段可作为局部封盖层,是中1井奥陶系鹰山组上油、下气油气分布的主要原因之一.%Mineral composition, micro-pore characteristics and well-logs from five wells were used to study the sealing capacity of the Ordovician carbonate rocks in Tazhong area,Tarim Basin. The Ordovician Lianglitage and Yingshan formations are at substage A-B of the middle diagenetic stage and substage A of the late diagenetic stage. For the Lianglitage Formation grainstone,the breakthrough pressure (BP) is 1. 81 -29. 76 Mpa,and the threshold radius (TR) is 13. 89 -77. 35 nm,. For the marlstones,the BP is 14. 33MPa and TR is 25. 9 -44. 51 nm. For the micritic limestone with band of argillite, the BP is 0. 98 - 10. 35 Mpa and the TR is 13. 52 - 142. 60 nm. The BP and the TR of the Yingshan Formation limy dolomites are 0. 98 - 10. 35 Mpa and 13. 52 - 142. 60 nm. Thus, the marlstone and partial grainstone of the Lianglitage Formation and the Yingshan Formation dolomite limestone have certain sealing capacity,with thickness over 5 m,BP over 5 Mpa,TR between 10-20 nm,pore throat radium

  9. Late recurrence of medulloblastoma.

    Science.gov (United States)

    Stevens, Brittney; Razzaqi, Faisal; Yu, Lolie; Craver, Randall

    2008-01-01

    We present a child with a cerebellar medulloblastoma, diagnosed at age three, treated with near total surgical resection, radiotherapy, and chemotherapy, that recurred 13 years after the initial diagnosis. This late recurrence exceeds the typical 10-year survival statistics that are in common use, and exceeds the Collins rule. Continued follow-up of these children is justified to increase the likelihood of detecting these late recurrences early and to learn more about these late recurrences.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

  11. Revision of the plectorthoid brachiopod Platystrophia dentata (Pander, 1830 from the Middle Ordovician of the East Baltic

    Directory of Open Access Journals (Sweden)

    Michael A. Zuykov

    2011-08-01

    Full Text Available Due to the scanty description of Porambonites dentata Pander, 1830 and loss of its single type specimen, the name dentata has been subsequently attributed to various Ordovician to Silurian species of the genus Platystrophia s.l. with two costae in the sulcus and three on the fold. In The Natural History Museum, London, there is a complete shell identified presumably by Christian Pander himself as Spirifer dentatus from Pulkowa. That specimen is selected here as neotype to Platystrophia dentata, i.e. to a species, which on the basis of new material is restricted to the lower Darriwilian in the St Petersburg region. Considering differences in the interior of the dorsal valve, the other species (some with subspecies of the so-called dentata-group, especially from the stratigraphically younger strata, are discussed and excluded from the material described here of P. dentata.

  12. The environmental response of Middle Ordovician large organic walled microfossils from the Goldwyer and Nita Formations, Canning Basin, Western Australia.

    Science.gov (United States)

    Winchester-Seeto, T; Foster, C; O'Leary, T

    2000-12-01

    Middle Ordovician large organic walled microfossils (chitinozoans, scolecodonts, hydrozoans and foraminiferal linings) were recovered from the upper Goldwyer and lower Nita formations, Canning Basin, Western Australia, from three cores (WMC Santalum 1A, Kunzea 1 and Acacia 2). Petrophysical logs of these cores reveal an overall upward shallowing supersequence, overprinted by numerous transgression/regression couplets that can be correlated over 100km.Analysis of the abundance of the microfossils with respect to the gamma log signatures reveals that both chitinozoan abundance and diversity decrease as water depth shallows; however, the opposite is not always true and other factors probably intervene. Scolecodonts show an increase in abundance in transgressions, while hydrozoans and foraminiferal linings show no consistent response to trangressive or regressive phases. Cyathochitina hunderumensis tends to dominate chitinozoan assemblages where there is a transgression, while species of Belonechitina replace Cy. hunderumensis in regressive phases.

  13. The eoorthid brachiopod Apheoorthina in the Lower Ordovician of NW Argentina and the dispersal pathways along western Gondwana

    Directory of Open Access Journals (Sweden)

    Diego F. Muñoz

    2016-08-01

    Full Text Available The eoorthid brachiopod Apheoorthina is reported for the first time from the Lower Ordovician of NW Argentina. It is represented by a species similar to A. ferrigena from the Tremadocian of the Prague Basin, increasing the faunal affinities between the Central Andean Basin and the South European microcontinents, in particular the Bohemian region (Perunica. Nine out of the fourteen brachiopod genera reported from the Tremadocian of the Central Andean Basin (~64% are shared with the Mediterranean region, four of which (~28% have been recorded in the Prague Basin, and two (Kvania and Apheoorthina are restricted to the Central Andes and Perunica. Dispersal pathways around Gondwana are analyzed in the light of major factors affecting large-scale distribution of brachiopods (environment, larval capacity for dispersal, oceanic currents. The presence in Apheoorthina aff. ferrigena of a well-preserved larval protegulum measuring 420 μm in width and 210 μm in length strongly suggests that this species had planktotrophic larvae capable of long-distance dispersal. According to recent ocean-atmosphere general circulation models for the Ordovician Period, the Central Andean margin was dominated by the cold-water Antarctica Current. Despite the complex non-zonal pattern produced by current deflections around the peri-Gondwanan microcontinents, the general westward circulation sense favoured larval dispersal from the Andean region to North Africa, Avalonia, the Armorican Terrane Assemblage, and Perunica. On the other hand, the eastwards flowing Gondwana Current connected the North Gondwana waters with the South American epicontinental seas, which could explain the reversed migration of some brachiopods.

  14. Very low-temperature metamorphism in Ordovician metasedimentary rocks above and below the Sardic unconformity, SW Sardinia, Italy

    Science.gov (United States)

    Franceschelli, M.; Battaglia, S.; Cruciani, G.; Pasci, S.; Puxeddu, M.

    2017-03-01

    In the Iglesiente region, the Cabitza and Monte Argentu Formations are separated by an angular unconformity known as the Sardic unconformity. This is related to an early Ordovician mild compressional phase, known as the "Sardic phase". The pelitic samples from the structurally lower Cabitza Formation consist of alternating reddish phyllosilicate-rich and whitish phyllosilicate-poor, sialic layers, whose S0 bedding plane is parallel to a pre-Variscan S1P schistosity overprinted by the Variscan S1V schistosity. Pelitic samples from the Monte Argentu Formation are characterized by a Variscan S1V axial plane schistosity. Samples from the two formations consist of quartz and phyllosilicates. The latter are potassic white mica, chlorite, paragonite, locally kaolinite, and pyrophyllite. The illite crystallinity values determined for the Cabitza samples are 0.25-0.31, with an average of 0.29; meanwhile, the Monte Argentu samples produce values of 0.33-0.38, with an average of 0.35. The chlorite crystallinity and b0 of potassic white mica values show greater heterogeneity in the Cabitza than the Monte Argentu samples. The b0 values and P-T pseudosections allow us to confirm that there is no significant difference in the P-T metamorphism conditions between the Cabitza and Monte Argentu samples. The Iglesiente region, which is considered to be the rift zone behind the Middle Ordovician Sarcidano-Barbagia volcanic arc, underwent the "Sardic phase", giving rise to E-W folds. These were first overprinted by weak E-W, and then by stronger N-S-oriented Variscan deformation events.

  15. Personality in Late Midlife

    DEFF Research Database (Denmark)

    Mortensen, Erik Lykke; Flensborg-Madsen, Trine; Molbo, Drude

    2014-01-01

    To analyze associations in late midlife between sex, age, education and social class, and the Big Five personality traits; to analyze associations between personality traits and cognitive ability in late midlife; and to evaluate how these associations are influenced by demographic factors....

  16. The Ordovician Sierras Pampeanas-Puna basin connection: Basement thinning and basin formation in the Proto-Andean back-arc

    Science.gov (United States)

    Büttner, Steffen H.

    2009-11-01

    The Ordovician Sierras Pampeanas, located in a continental back-arc position at the Proto-Andean margin of southwest Gondwana, experienced substantial mantle heat transfer during the Ordovician Famatina orogeny, converting Neoproterozoic and Early Cambrian metasediments to migmatites and granites. The high-grade metamorphic basement underwent intense extensional shearing during the Early and Middle Ordovician. Contemporaneously, up to 7000 m marine sediments were deposited in extensional back-arc basins covering the pre-Ordovician basement. Extensional Ordovician tectonics were more effective in mid- and lower crustal migmatites than in higher levels of the crust. At a depth of about 13 km the separating boundary between low-strain solid upper and high-strain lower migmatitic crust evolved to an intra-crustal detachment. The detachment zone varies in thickness but does not exceed about 500 m. The formation of anatectic melt at the metamorphic peak, and the resulting drop in shear strength, initiated extensional tectonics which continued along localized ductile shear zones until the migmatitic crust cooled to amphibolite facies P-T conditions. P-T-d-t data in combination with field evidence suggest significant (ca. 52%) crustal thinning below the detachment corresponding to a thinning factor of 2.1. Ductile thinning of the upper crust is estimated to be less than that of the lower crust and might range between 25% and 44%, constituting total crustal thinning factors of 1.7-2.0. While the migmatites experienced retrograde decompression during the Ordovician, rocks along and above the detachment show isobaric cooling. This suggests that the magnitude of upper crustal extension controls the amount of space created for sediments deposited at the surface. Upper crustal extension and thinning is compensated by newly deposited sediments, maintaining constant pressure at detachment level. Thinning of the migmatitic lower crust is compensated by elevation of the crust

  17. The messaoudensis-trifidum acritarch assemblage (Ordovician: late Tremadoc-early Arenig) of the Barriga Shale Formation, Sierra Morena (SW-Spain).

    Science.gov (United States)

    Servais, T; Mette, W

    2000-12-01

    The "messaoudensis-trifidum acritarch assemblage" is currently considered to be characteristic of latest Tremadoc-earliest Arenig cold-water environments on the periphery of Gondwana, at high latitudes in the southern hemisphere. An integrated biostratigraphical study on both acritarchs and graptolites was until now only available for localities in northwest England. Reinvestigation of the "messaoudensis-trifidum acritarch assemblage" from the Barriga Formation (Sierra Morena, southwestern Spain), which contains some graptolite horizons that can be attributed to the latest Tremadoc (pre-phyllograptoides and pre-approximatus graptolite biozones), strengthens the biostratigraphical potential of the "messaoudensis-trifidum assemblage", and the importance of some of the acritarch taxa recovered from these levels. It is concluded that the acritarch genera Coryphidium Vavrdová, 1972, Peteinosphaeridium Staplin et al., 1965 emend. Playford et al., 1995, Striatotheca, Burmann, 1970, and the Veryhachium lairdii group (rectangular veryhachiids) appear in the latest Tremadoc, and should not be considered as indicators of the base of the Arenig, as previously suggested.

  18. Tectonic and eustatic control on the distribution of black-shale source beds in the Wufeng and Longmaxi formations (Ordovician-Silurian),South China

    Institute of Scientific and Technical Information of China (English)

    SU Wenbo; ZHAO Huijing; LI Zhiming; Ettensohn F.R.; Johnson M.E.; Huff W.D.; WANG Wei; MA Chao; LI Lu; ZHANG Lei

    2007-01-01

    It is known that high-quality,black-shale source rocks occur in the uppermost Ordovician Wufeng Formation and in the lowermost Silurian Longmaxi Formation in South China.Hence,it is important to understand their lithostratigraphy and the controls on their deposition.A review of lithostratigraphic criteria for subdividing the two adjacent formations provides new regional correlations between the formations and related stratigraphic successions and facies.Both the black shales and the related,overlying flysch deposits at the Ordovician-Silurian transition in South China appear to have migrated northwestward in time and space,reflecting probable flexural control in a foreland basin that developed in response to subduction-type orogeny southeast of the Yangtze block.The black shales also contain K-bentonites from explosive,felsic-intermediate volcanism,the distribution of which also supports orogeny to the southeast.Finally,the analysis of sequence stratigraphy,which shows that the initiation of transgressive system tracts (TST) and condensed section (CS) in the related third-order sequences coincided with the two black-shale horizons respectively,indicates that the main controlling factors for the deposition of the Ordovician-Silurian black shales in South China are (1)northwestwardly migrating,foreland-basin subsidence caused by deformational loading related to episodic accretion of the Cathaysia block to the Yangtze block during this period,and (2) the anoxic,sediment-starved water column caused by rapid rise of the sea-level during the two successive phases of third-order global sea-level rise near the Ordovician-Silurian transition in South China.In future exploration for hydrocarbon source rocks in the area,it is important to consider likely flexural and eustatic causes for subsiding,deep,anoxic seas in recognizing other source rock intervals,and our understanding of the Wufeng and Longmaxi formations may serve as models for future source rock exploration.

  19. Late-Stage Caregiving

    Science.gov (United States)

    ... resources, care and ways to engage in meaningful connections. During the late stages, your role as a ... drinks. This will help you track the person's natural routine, and then you can plan a schedule. ...

  20. Suicides in late life.

    Science.gov (United States)

    Van Orden, Kimberly; Conwell, Yeates

    2011-06-01

    Suicide in late life is an enormous public health problem that will likely increase in severity as adults of the baby boom generation age. Data from psychological autopsy studies supplemented with recent studies of suicidal ideation and attempts point to a consistent set of risk factors for the spectrum of suicidal behaviors in late life (suicide ideation, attempts, and deaths). Clinicians should be vigilant for psychiatric illness (especially depression), physical illness, pain, functional impairment, and social disconnectedness. Recent advances in late-life suicide prevention have in common collaborative, multifaceted intervention designs. We suggest that one mechanism shared by all preventive interventions shown to reduce the incidence of late-life suicide is the promotion of connectedness. For the clinician working with older adults, our recommendation is to not only consider risk factors, such as depression, and implement appropriate treatments but to enhance social connectedness as well.

  1. The characteristics and sources of natural gases from Ordovician weath-ered crust reservoirs in the Central Gas Field in the Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    LI Xianqing; HU Guoyi; LI Jian; HOU Dujie; DONG Peng; SONG Zhihong; YANG Yunfeng

    2008-01-01

    The Central Gas Field is a famous large-sized gas field in the Ordos Basin of China. However, identification of main gas sources of the Ordovician reservoirs in this gas field remains puzzling. On the basis of a lot of geochemical data and geological research on natural gases, the characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin were studied. The results indicated that natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin have similar chemical and isotopic com-positions to highly mature and over-mature dry gases. Both coal-derived gases and oil-type gases coexist in the Central Gas Field in the Ordos Basin. The former was derived mainly from Carboniferous-Permian coal measures and the latter from Lower Paleozoic marine carbonates. It is suggested that coal-derived gases occur in the eastern part of the Central Gas Field while oil-type gases may be pro-duced mainly in the northern, western and southern parts of the Central Gas Field in the Ordos Basin.

  2. Distribution of the Ordovician Fluid in the Tahe Oilfield and Dynamic Response of Cave System $48 to Exploitation

    Institute of Scientific and Technical Information of China (English)

    LOU Zhanghua; ZHU Rong; YUN Lu; RAN Qihua; SU Danyang; LI Mei

    2008-01-01

    The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-karst cyclic sedimentation. Due to significant heterogeneity of the reservoir, the distribution of oil and water is complicated. Horizontally, a fresh water zone due to meteoric water can be found in the north part of the Akekule uplift. A marginal freshening zone caused by water released from mudstone compaction is found at the bottom of the southern slope. Located in a cross- formationai flow discharge zone caused by centripetal and the centrifugal fows, the main part of the Tahe Oilfield, featuring high salinity and concentrations of CI- and K++Na+, is favorable for accumulation of hydrocarbon. Three types of formation water in the Tahe Ordovician reservoir are identified: (1) residual water at the bottom of the cave after oil and gas displacement, (2) residual water in fractures/pores around the cave after oil and gas displacement, and (3) interlayer water below reservoirs. The cave system is the main reservoir space, which consists of the main cave, branch caves and depressions between caves. Taking Cave System $48 in the Ordovician reservoir as an example, the paper analyzes the fluid distribution and exploitation performance in the cave system. Owing to evaporation of groundwater during cross-formational flow, the central part of the main cave, where oil layers are thick and there is a high degree of displacement, is characterized by high salinity and Brconcentration. With high potential and a long stable production period, most wells in the central part of the main cave have a long water-free oil production period. Even after water breakthrough, the water content has a slow or stepwise increase and the hydrochemistral characteristics of the produced water in the central part of the main cave are uniform. From the center to the edge of the main

  3. U-Pb Zircon geochronology of the Cambro-Ordovician metagranites and metavolcanic rocks of central and NW Iberia

    Science.gov (United States)

    Talavera, C.; Montero, P.; Bea, F.; González Lodeiro, F.; Whitehouse, M.

    2013-01-01

    New U-Pb zircon data from metagranites and metavolcanic rocks of the Schist-Graywacke Complex Domain and the Schistose Domain of Galicia Tras-os-Montes Zone from central and NW Iberia contribute to constrain the timing of the Cambro-Ordovician magmatism from Central Iberian and Galicia Tras-os-Montes Zones which occurred between 498 and 462 Ma. The crystallization ages of the metagranites and metavolcanic rocks from the northern Schist-Graywacke Complex Domain are as follows: (a) in west Salamanca, 489 ± 5 Ma for Vitigudino, 486 ± 6 Ma for Fermoselle and 471 ± 7 Ma for Ledesma; (b) in northern Gredos, 498 ± 4 Ma for Castellanos, 492 ± 4 Ma for San Pelayo and 488 ± 3 Ma for Bercimuelle; (c) in Guadarrama, 490 ± 5 Ma for La Estación I, 489 ± 9 Ma for La Cañada, 484 ± 6 Ma for Vegas de Matute (leucocratic), 483 ± 6 Ma for El Cardoso, 482 ± 8 Ma for La Morcuera, 481 ± 9 Ma for Buitrago de Lozoya, 478 ± 7 Ma for La Hoya, 476 ± 5 Ma for Vegas de Matute (melanocratic), 475 ± 5 Ma for Riaza, 473 ± 8 Ma for La Estación II and 462 ± 11 Ma for La Berzosa; and (d) in Toledo, 489 ± 7 Ma for Mohares and 480 ± 8 Ma for Polán. The crystallization ages of the metagranites from the Schistose Domain of Galicia Tras-os-Montes Zone are 497 ± 6 Ma for Laxe, 486 ± 8 Ma for San Mamede, 482 ± 7 Ma for Bangueses, 481 ± 5 Ma for Noia, 480 ± 10 for Rial de Sabucedo, 476 ± 9 Ma for Vilanova, 475 ± 6 Ma for Pontevedra, 470 ± 6 Ma for Cherpa and 462 ± 8 Ma for Bande. This magmatism is characterized by an average isotopic composition of (87Sr/86Sr)485Ma ≈ 0.712, (ɛNd)485Ma ≈ -4.1 and (TDM) ≈ 1.62 Ga, and a high zircon inheritance, composed of Ediacaran-Early Cambrian (65 %) and, to a lesser extent, Cryogenian, Tonian, Mesoproterozoic, Orosirian and Archean pre-magmatic cores. Combining our geochronological and isotopic data with others of similar rocks from the European Variscan Belt, it may be deduced that Cambro-Ordovician magmas from this belt were mainly

  4. Testing alternative tectonic models of Palaeotethys in the E Mediterranean region: new U-Pb and Lu-Hf isotopic analyses of detrital zircons from Late Carboniferous and Late Triassic sandstones associated with the Anatolide and Tauride blocks (S Turkey)

    Science.gov (United States)

    Ustaömer, Timur; Ayda Ustaömer, Petek; Robertson, Alastair; Gerdes, Axel

    2016-04-01

    Alternative tectonic models of Palaeotethys during Late Palaeozoic-Early Mesozoic time infer: 1. southward subduction beneath the north margin of Gondwana; 2. northward subduction beneath the south margin of Eurasia, or 3. double subduction (northwards and southwards), at least during Late Carboniferous. U-Pb and Lu-Hf isotopic analysis of detrital zircons, extracted from sandstones, can provide strong indications of age and identity of source terranes. Here, we consider the provenance of both Late Carboniferous and Late Triassic sandstones from both relatively allochthonous and relatively autochthonous units that are all spatially associated with the Anatolide and Tauride continental blocks. The relatively allochthonous units are sandstones (3 samples) from the Late Carboniferous Aladaǧ Nappe (Tauride; in the east), the Konya Complex (Anatolide; central area) and the Karaburun Mélange (Tauride-related; in the west). The relatively autochthonous units are Late Triassic sandstones (4 samples) from the Üzümdere Formation, the Kasımlar Formation (both western Taurides) and the Güvercinlik Formation (Karaburun Peninsula-Tauride related; far west). The Late Carboniferous sandstones from the three relatively allochthonous units are dominated by Precambrian zircon populations, the age distribution of which suggests derivation from two contrasting source regions: First, a NE African-type source (i.e. Saharan craton) for the sandstones of the Konya Mélange and the Aladaǧ Nappe because these sediments have prominent zircon populations dated at 0.5-0.7, 0.8 and 0.9-1.1 Ga. Palaeozoic zircons are minimal in the sandstones of the Aladaǧ Nappe and the Konya Complex (3 and 5% of the whole data, respectively) and are confined to Cambrian to Ordovician. Secondly, a contrasting NW African-type source is inferred for sandstone from the Karaburun Mélange because of the marked absence of Tonian-Stenian zircons and the predominance of ~2 Ga zircons over ~2.5 Ga zircons. In

  5. Cosmic-ray exposure ages of fossil micrometeorites from mid-Ordovician sediments at Lynna River, Russia

    CERN Document Server

    Meier, Matthias M M; Lindskog, Anders; Maden, Colin; Wieler, Rainer

    2014-01-01

    We measured the He and Ne concentrations of 50 individual extraterrestrial chromite grains recovered from mid-Ordovician (lower Darriwilian) sediments from the Lynna River section near St. Petersburg, Russia. High concentrations of solar wind-like He and Ne found in most grains indicate that they were delivered to Earth as micrometeoritic dust, while their abundance, stratigraphic position and major element composition indicate an origin related to the L chondrite parent body (LCPB) break-up event, 470 Ma ago. Compared to sediment-dispersed extraterrestrial chromite (SEC) grains extracted from coeval sediments at other localities, the grains from Lynna River are both highly concentrated and well preserved. As in previous work, in most grains from Lynna River, high concentrations of solar wind-derived He and Ne impede a clear quantification of cosmic-ray produced He and Ne. However, we have found several SEC grains poor in solar wind Ne, showing a resolvable contribution of cosmogenic 21Ne. This makes it possi...

  6. Isotopic evidence for glacial meltwater recharge to the Cambrian-Ordovician aquifer, north-central United States

    Science.gov (United States)

    Siegel, D.I.; Mandle, R.J.

    1984-01-01

    The chemistry of water in the Cambrian-Ordovician aquifer in six midwestern states has been studied as part of the Northern Midwest Regional Aquifer-System Analysis of the U.S. Geological Survey. Dissolved-solids concentrations generally increase perpendicular to the direction of regional groundwater flow, from less than 400 mg/liter in southeast Minnesota, southwest Wisconsin, and northeast Iowa to more than 10,000 mg/liter in northwest Missouri. Isotopic ratios of hydrogen and oxygen are significantly depleted from north to south, with an areal distribution approximately parallel to the distribution of dissolved solids. For example, ??18O in southern Iowa and northern Missouri is about 6 parts per thousand lighter than ??18O of modern recharge water in Minnesota and Wisconsin. Covariance between ??18O and ??D of the groundwater, similar to that of modern precipitation, suggests that the differences in isotopic ratios between groundwater and modern recharge water reflect meteoric signatures of water during past recharge events rather than geochemical processes such as isotopic exchange with aquifer materials. The pronounced parallelism between the distribution of isotopes and dissolved solids over large areas probably reflects largescale recharge of Pleistocene glacial meltwater into the aquifer system, which probably had a paleoflow system with a gradient from northeast to southwest rather than from northwest to southeast. ?? 1984.

  7. Petrography, Geochemistry and Proposed Genesis of Ordovician Oolitic Iron Formation Members of the Lashkarak Formation, Eastern Alborz

    Directory of Open Access Journals (Sweden)

    Mansoore Maghsoudloo Mahalli

    2016-07-01

    Full Text Available Introduction Oolitic iron formations are sedimentary rocks with >5 vol.% oolites and >15 wt.% iron, corresponding to 21.4 wt.% Fe2O3 (Young, 1989; Petranek and Van Houten, 1997; Mucke and Farshad, 2005. In Iran, new iron oolite-bearing members have been identified in the Lashkarak Formation (lower-middle Ordovician in the Abarsej, Dehmola and Simehkuh sections, eastern Alborz (Ghobadi Pour et al., 2011. At present, the mineralogy and geochemistry of these members are not known. Consequently, research reported here was conducted to reveal the mineralogical and geochemical characteristics of Ordovician oolitic iron formationmembers and to discuss their genesis and economic importance. Materials and Analyses Field geology and sampling was carried out to collect 25 samples from the ooliticiron formation members in the Abarsej, Dehmola and Simehkuh section in eastern Alborz. Samples were prepared for polished-thin sections (n=10, XRD analysis (n=15. Whole-rock chemical analysis (n=15 by XRF for major elements and by ICP-ES for trace elements was performed by laboratories at the SarCheshmeh copper mine complex, Kerman, Iran. One sample was analyzed by SEM at the Wales Museum, UK. Results Microscopic studies show that the oolitic iron formation members are hosted by carbonate argillite rocks. They are mainly composed of oolites rather than pisoliths (small bodies somewhat larger and more irregular than oolites, whereas oolites have mainly ellipsoidal forms and locally spherical shapes. Most (6 oolites show banding with a central core. Simple oolites without a core are scarce. Mineralogically, oolites are mainly chamositic and hematitic in composition; goethite, pyrite and glauconite occur in traces and siderite is absent. Quartz, calcite and zircon are accessory minerals which are present in the groundmass. Geochemically, TFeO % of the oolitic iron formation horizons ranges from 8 to 48 % with an average of 21%. The CaO content ranges from 2 to 37% and

  8. Tectonic evolution of Tarim basin in Cambrian–Ordovician and its implication for reservoir development, NW China

    Indian Academy of Sciences (India)

    Yu Bingsong; Ruan Zhuang; Zhang Cong; Pan Yinglu; Lin Changsong; Wang Lidong

    2016-03-01

    In order to find the impact of regional tectonic evolution of Tarim basin on the inside distribution of sedimentary facies and reservoir development, this paper, based on the research of plate-tectonic evolution of Tarim basin, conducts an in-depth analysis on the basin’s inside sedimentary response to the Eopaleozoicregional geodynamic reversion from extension to convergence around Tarim plate, and concludes that the regional geodynamic environment of surrounding areas closely contributes to the formation and evolution of paleo-uplifts, differentiation of sedimentary facies in platform, distribution of high-energyreef and bank facies belts, conversion of sedimentary base level from fall to rise, obvious change of lithology from dolomite to limestone, and formation of several unconformity surfaces in Ordovician system in the basin. A series of sedimentary responses in the basin are controlled by regional dynamic setting, which not only controls the distribution of reservoirs in reef and bank facies but also restricts the development and distribution of karst reservoirs controlled by the unconformity surfaces. This offers the macro geological evidences for us to further analyze and evaluate the distribution of favorable reservoirs.

  9. Burial Dissolution of Ordovician Granule Limestone in the Tahe Oilfield of the Tarim Basin, NW China, and Its Geological Significance

    Institute of Scientific and Technical Information of China (English)

    LIU Chunyan; LIN Changsong; WANG Yi; WU Maobing

    2008-01-01

    With a comprehensive study on the petrology, geology and geochemistry of some Ordovician granule limestone samples in the Tahe Oilfieid of the Tarim Basin, two stages of burial dissolution were put forward as an in-source dissolution and out-source dissolution based on macro-microcosmic petrology and geochemistry features. The main differences in the two stages arc in the origin and moving pass of acid fluids. Geochemical evidence indicates that burial dissolution fluids might be ingredients of organic acids, CO2 and H2S associated with organic matter maturation and hydrocarbon decomposition, and the in-source fuid came from organic matter in the granule limestone itself, but the out-source was mainly from other argillaceous carbonate rocks far away. So, the forming of a burial dissolution reservoir resulted from both in-source and the out-source dissolutions. The granule limestone firstly formed unattached pinholes under in-source dissolution in situ, and afterwards suffered wider dissolution with out-source fluids moving along unconformities, seams, faults and associate fissures. The second stage was much more important, and the mineral composition in the stratum and heat convection of the fluid were also important in forming favorable reservoirs.

  10. An Evaluation of the Carbon Sequestration Potential of the Cambro-Ordovician Strata of the Illinois and Michigan Basins

    Energy Technology Data Exchange (ETDEWEB)

    Kirksey, Jim; Ansari, Sajjad; Malkewicz, Nick; Leetaru, Hannes

    2014-01-01

    The Knox Supergroup is a significant part of the Cambrian-Ordovician age sedimentary deposition in the Illinois Basin. While there is a very small amount of oil production associated with the upper Knox, it is more commonly used as a zone for both Class I and Class II disposal wells in certain areas around the state. Based on the three penetrations of the Knox Formation at the Illinois Basin – Decatur Project (IBDP) carbon dioxide (CO2) sequestration site in Macon County, Illinois, there is potential for certain zones in the Knox to be used for CO2 sequestration. More specifically, the Potosi member of the Knox Formation at about –3,670 feet (ft) subsea depth would be a candidate as all three penetrations had massive circulation losses while drilling through this interval. Each well required the setting of cement plugs to regain wellbore stability so that the intermediate casing could be set and successfully cemented to surface. Log and core analysis suggests significant karst porosity throughout the Potosi member. The purpose of this study is to develop a well plan for the drilling of a CO2 injection well with the capability to inject 3.5 million tons per annum (3.2 million tonnes per annum [MTPA] CO2 into the Knox Formation over a period of 30 years.

  11. Tectonic evolution of Tarim basin in Cambrian-Ordovician and its implication for reservoir development, NW China

    Science.gov (United States)

    Bingsong, Yu; Zhuang, Ruan; Cong, Zhang; Yinglu, Pan; Changsong, Lin; Lidong, Wang

    2016-03-01

    In order to find the impact of regional tectonic evolution of Tarim basin on the inside distribution of sedimentary facies and reservoir development, this paper, based on the research of plate-tectonic evolution of Tarim basin, conducts an in-depth analysis on the basin's inside sedimentary response to the Eopaleozoic regional geodynamic reversion from extension to convergence around Tarim plate, and concludes that the regional geodynamic environment of surrounding areas closely contributes to the formation and evolution of paleo-uplifts, differentiation of sedimentary facies in platform, distribution of high-energy reef and bank facies belts, conversion of sedimentary base level from fall to rise, obvious change of lithology from dolomite to limestone, and formation of several unconformity surfaces in Ordovician system in the basin. A series of sedimentary responses in the basin are controlled by regional dynamic setting, which not only controls the distribution of reservoirs in reef and bank facies but also restricts the development and distribution of karst reservoirs controlled by the unconformity surfaces. This offers the macro geological evidences for us to further analyze and evaluate the distribution of favorable reservoirs.

  12. Palaeogeography and palaeoecology of early Floian (Early Ordovician cephalopods from the Upper Fezouata Formation, Anti-Atlas, Morocco

    Directory of Open Access Journals (Sweden)

    B. Kröger

    2012-08-01

    Full Text Available In the central Anti-Atlas (Morocco, the Early Ordovician succession consists of about 1000 m of fossiliferous argillites and siltstones. The Upper Fezouata Formation (Floian contains a comparatively rich and abundant cephalopod association. A small collection of these cephalopods is described herein for the first time. The cephalopods are interpreted as autochthonous or parautochthonous, representing a fauna, which originally lived nektobenthically in the open water above the sediments or related to the sea bottom. The cephalopod associations of the Upper Fezouata Formation are similar to other contemporaneous assemblages known from higher palaeolatitudes and associated with deeper depositional settings and in siliciclastically dominated deposits. They are composed almost exclusively of slender orthocones, in this case predominantly of Destombesiceras zagorense n. gen., n. sp., which is interpreted as an early discosorid. Bathmoceras australe Teichert, 1939 and Bathmoceras taichoutense n. sp. from the Upper Fezouata Formation are at present the earliest unambiguous occurrences of bathmocerid cephalopods. Epizoans on the shell of a specimen of Rioceras are the earliest evidence of bryozoans growing as potential hitchhikers on cephalopod shells, indicating an early exploitation of a pseudoplanktonic lifestyle in this phylum. doi:10.1002/mmng.201200004

  13. Late Sovereign Diplomacy

    DEFF Research Database (Denmark)

    Adler-Nissen, Rebecca

    2009-01-01

    the promotion of national interests with those of the Union. In this late sovereign phase of diplomacy, political and legal authorities overlap, territorial exclusivity is replaced with functional boundaries, and states begin to speak with one voice. The article explores three interlinked aspects of late...... sovereign diplomacy: the teleological interpretation of the EC and EU treaties; the intense socialization of state representatives; and the negotiation process, which promotes national positions as part of a European cause, thereby delocalizing the national interest. While the EU has not rendered national...... diplomacy obsolete, it has profoundly changed its meaning and consequences....

  14. 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...... teenage mothers. The purpose is to study if results will be consistent with the hypotheses that poverty, social deprivation during adolescence and low education are causes of teen childbearing but also childlessness among elder women in the age group 32 to 37 years old. Could childlessness as well...... pregnant teenagers who had an induced abortion. Quite the opposite pattern is disclosed for late motherhood....

  15. Late Embryogenesis Abundant Proteins

    NARCIS (Netherlands)

    Shih, M.D.; Hoekstra, F.A.; Hsing, Y.I.C.

    2008-01-01

    During the late maturation stage of seed development, water content decreases greatly. One of the most striking characteristics of mature orthodox seeds is their ability to withstand severe desiccation. Mechanisms of plant drought/desiccation tolerance have been studied by numerous groups, and a bro

  16. Never Too Late

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A historical issue is being raised on Capitol Hill.In late May,members of the U.S.Congress introduced bipartisan resolutions in both chambers,calling on the federal legislature to acknowledge formally and express regret for discriminatory legislation and how the country accordingly treated Chinese immigrants more than a century ago.

  17. Big Java late objects

    CERN Document Server

    Horstmann, Cay S

    2012-01-01

    Big Java: Late Objects is a comprehensive introduction to Java and computer programming, which focuses on the principles of programming, software engineering, and effective learning. It is designed for a two-semester first course in programming for computer science students.

  18. Was I Late

    Institute of Scientific and Technical Information of China (English)

    叶历来; 罗琪芳

    2011-01-01

    “Get up, Jane!” “Oh... Mom, let me sleep five more minutes. I'm so Ured ( 困的 ).” “It's 7:50. It's too late. ” “OK, three minutes then... Wait! What did you say? What time is it? It's 7:50.”

  19. From Flysch to Molasse-Sedimentary and Tectonic Evolution of Late Caledonian-Early Hercynian Foreland Basin in North Qilian Mountains

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The Late Caledonian to Early Hercynian North Qilian orogenic belt in northwestern China is an elongate tectonic unit situated between the North China plate in the north and the Qaidam plate in the south. North Qilian started in the latest Proterozoic to Cambrian as a rift basin on the southern margin of North China, and evolved later to an archipelagic ocean and active continental margin during the Ordovician and a foreland basin from Silurian to the Early and Middle Devonian. The Early Silurian flysch and submarine alluvial fan, the Middle to Late Silurian shallow marine to tidal flat deposits and the Early and Middle Devonian terrestrial molasse are developed along the corridor Nanshan. The shallowing-upward succession from subabyssal flysch, shallow marine, tidal flat to terrestrial molasse and its gradually narrowed regional distribution demonstrate that the foreland basin experienced the transition from flysch stage to molasse stage during the Silurian and Devonian time.

  20. Paleomagnetic studies on the late Ediacaran - Early Cambrian Puncoviscana and the late Cambrian Campanario formations, NW Argentina: New paleogeographic constraints for the Pampia terrane

    Science.gov (United States)

    Franceschinis, Pablo R.; Rapalini, Augusto E.; Escayola, Monica P.; Luppo, Tomás

    2016-10-01

    A magnetofabric and paleomagnetic study was carried out in the Late Ediacaran - Early Cambrian Puncoviscana and the early Late Cambrian Campanario formations, exposed in Santa Victoria Oeste, in northwestern Argentina. Ten sites (93 samples) were located in tuffs and volcanic sills interbedded in the Puncoviscana Formation, one of which had been dated at 537 ± 0.9 Ma. On the other hand, 42 samples were collected at three sites from red to purple sandstones of the Campanario Formation. The analysis of anisotropy of magnetic susceptibility (AMS) allowed to recognize a pre-Andean fabric in both formations indicating that it is previous to the Andean cycle. In the paleomagnetic study reliable magnetic components were isolated in only two sites of the Puncoviscana formation whose virtual geomagnetic poles (VGPs) are close to but do not coincide with the apparent polar wander path of Río de la Plata craton - Gondwana for the late Neoproterozoic - Cambrian. A new paleomagnetic pole (18.2°S, 358.8°W, K: 27.9; A95: 3.9) was computed for the Campanario formation which is close to but does not coincide with those obtained in other locations for this unit and were considered anomalous respect to the expected position in the Gondwana path. The pole presented here is closer to the apparent polar wander path of Gondwana for the Late Cambrian-Early Ordovician suggesting two possible interpretations; the presence of different amounts of Andean tectonic rotations between different sampling locations of the Campanario Formation or the recording of a rapid Pampia dextral displacement along the Rio de la Plata craton margin in Cambrian times.

  1. Subsolidus alkali metasomatism in the metamorphosed Ordovician acid volcanics and volcaniclastics of the Gelnica Group (Gemeric Superunit, Western Carpathians

    Directory of Open Access Journals (Sweden)

    Mária Šimurková

    2016-06-01

    Full Text Available The Early Paleozoic Gelnica Group (Gemeric Superunit, Western Carpathians is composed of low-grade metamorphosed flysch-like sedimentary complexes alternated with volcanogenic complexes built up mostly by acid volcaniclastic rocks. Volcaniclastic rocks and small rhyolite bodies Ordovician in age underwent subsolidus alkali metasomatism locally overprinted by multiple stages of younger metamorphic and hydrothermal alterations. The observed variability in chemical compositions indicates that the most of acid volcanic and volcaniclastic rocks experienced potassic or sodium metasomatic alteration, the unaltered or Mg-metasomatised rocks occur less frequently. The dominating K-metasomatism is related mainly to the K-feldspar, partly also biotite and muscovite/sericite formation at the expense of matrix or original feldspar phenocrysts. The Na-metasomatism is connected with albite formation. The highest concentrations of alkalies (up to 13.52 wt. % K2O and 7.08 wt. % Na2O respectively have been found in rocks originally represented by glassy dacites. The elements like Al, Ti and Zr remain immobile in alkaline metasomatic processes in contrast to Rb or metals. Based on the results from areas with analogical geological structure and evolution, especially the Bergslagen area in Sweden, we suppose that alkali metasomatism in the Gelnica Group is a product of hydrothermal system caused by the infiltration and circulation of sea water. The areas with K-, Na- or Mg-metasomatism represent different parts of the original hydrothermal system, where the K-metasomatism was probably its lower temperature section. This hydrothermal system probably mobilised some metals (Cu, Pb, Zn, Fe, Mn for the formation of stratiform sulfide and oxide mineralizations or served as the metal pre-concentrator for younger siderite-sulfide vein deposits.

  2. Origin and timing of siderite cementation in Upper Ordovician glaciogenic sandstones from the Murzuq basin, SW Libya

    Energy Technology Data Exchange (ETDEWEB)

    El-ghali, M.A.K.; Mansurbeg, H. [Department of Earth Science, Uppsala University, Villavaegen 16, SE 75236 Uppsala (Sweden); Tajori, K.G. [Department of Earth Science, Faculty of Science, Al-Fateh University, P.O. Box 13696, Tripoli (Libya); Ogle, N.; Kalin, R.M. [School of Civil Engineering, Environmental Engineering Research Centre, The Queen' s University of Belfast, Stranmillis Road, Belfast BT9 5AG (United Kingdom)

    2006-05-15

    The origin and timing of siderite cementation have been constrained in relation to depositional facies and sequence stratigraphy of Upper Ordovician glaciogenic sandstones from the Murzuq basin, SW Libya. Optical microscope, backscattered electron imagery, and carbon and oxygen stable isotope analysis have revealed that siderite is of eo- and mesogenetic origin. Eogenetic siderite is Mg-poor with a mean composition of (Fe{sub 91.7}Mg{sub 1.5}Ca{sub 0.3}Mn{sub 6.5})CO{sub 3}, and occurs in paraglacial, tide-dominated deltaic highstand systems tract (HST) sandstones, in paraglacial, foreshore to shoreface HST sandstones and in postglacial, Gilbert-type deltaic lowstand systems tract (LST) sandstones. This siderite is typically of meteoric water origin that influxed into the LST and HST sandstones during relative sea level fall and basinward shift of the strandline. Mesogenetic siderite, which engulfs and thus postdates quartz overgrowths and illite, is Mg-rich with a mean composition of (Fe{sub 72.2}Mg{sub 21.7}Ca{sub 0.8}Mn{sub 5.3})CO{sub 3} and occurs in the paraglacial, tide-dominated deltaic HST sandstones, in paraglacial foreshore to shoreface HST sandstones, in glacial, tide-dominated estuarine transgressive systems tract (TST) sandstones, in postglacial, Gilbert-type deltaic LST sandstones, and in postglacial, shoreface TST sandstones. {delta}{sup 18}O{sub V-PDB} values of this siderite, which range between -22.6 and -13.8%%, suggest that precipitation has occurred from evolved formation waters with {delta}{sup 18}O values between -14.0 and +1.0%% and was either meteoric, mixed marine-meteoric and/or marine in origin by assuming postdating quartz overgrowths and illite temperature between 80 and 130{sup o}C. (author)

  3. Ordovician ocean plate stratigraphy and thrust duplexes of the Ballantrae Complex, SW Scotland: Implications for the pelagic deposition rate and forearc accretion in the closing Iapetus Ocean

    Science.gov (United States)

    Fujisaki, Wataru; Asanuma, Hisashi; Suzuki, Kazue; Sawaki, Yusuke; Sakata, Shuhei; Hirata, Takafumi; Maruyama, Shigenori; Windley, Brian F.

    2015-11-01

    The Ballantrae Complex (at Bennane Lea in SW Scotland) contains important ocean plate stratigraphy (basalt, chert, mudstone, sandstone) in an accretionary prism that is associated with a classic Ordovician ophiolite. We used the ocean plate stratigraphy to sub-divide the prism into 11 tectonic units. To determine the depositional age of bedded cherts, zircons were separated from 9 tuff beds from 6 different units. All the tuffs have early to middle Ordovician ages, even though their present positions are mutually distant. These ages are consistent with microfossil records of radiolaria and graptolites. The stratigraphic-structural relationships demonstrate that the ocean plate stratigraphy has been repeated by bedding-parallel thrusts; this is typical of a modern accretionary duplex. We calculated the sedimentation rate of Early to Middle Ordovician bedded cherts at Bennane Lea on the basis of U-Pb zircon ages obtained from several tuff beds; the data indicate that the depositional rate (0.6-3 m/myr) was as slow as that of Mesozoic-Cenozoic equivalents defined by radiolaria. The age spectra of detrital zircons from Ballantrae sandstones show prominent single peaks at ca. 467 and 478 Ma, and a lack of Precambrian zircons. Integration of our new zircon ages with published isotopic data and palaeo-geographic maps indicates that the sandstones were deposited near an intra-oceanic arc and far from any continent containing Precambrian rocks. The pelagic-to-clastic sediments at Bennane Lea were deposited in the closing Iapetus Ocean from ca. 477 Ma to ca. 464 Ma, when they were accreted with the intra-oceanic arc of Ballantrae.

  4. Late-Onset Asthma

    DEFF Research Database (Denmark)

    Ulrik, Charlotte Suppli

    2017-01-01

    Late-onset asthma is common, associated with poor outcome, underdiagnosed and undertreated, possibly due to the modifying effect of ageing on disease expression. Although the diagnostic work-up in elderly individuals suspected of having asthma follows the same steps as in younger individuals (case......, to objectively confirm asthma. If necessary, a trial of oral or inhaled corticosteroid might be necessary. Asthma can be diagnosed when increased airflow variability is identified in a symptomatic patient, and if the patient does not have a history of exposure, primarily smoking, known to cause chronic...... obstructive pulmonary disease, the diagnosis is asthma even if the patient does not have fully reversible airflow obstruction. Pharmacological therapy in patients with late-onset asthma follows international guidelines, including treatment with the lowest effective dose of inhaled corticosteroid to minimize...

  5. Late Babylonian Astrology

    Science.gov (United States)

    Steele, John M.

    The last five centuries BC saw the development of several new forms of astrology in Babylonia. Key to these new astrological techniques was the invention of the zodiac in about 400 BC. These new forms of astrology include personal horoscopes, astral medicine, and the exploitation of geometrical relationships between the position of heavenly bodies. Several Late Babylonian astrological doctrines were later adopted within Greek astrology.

  6. 9th International Symposium on the Ordovician System, 7th International Graptolite Conference & Field Meeting of the International Subcommission on Silurian Stratigraphy

    Institute of Scientific and Technical Information of China (English)

    FlorencioG.Acenolaza; GuillermoF.Acenolaza; SilvioH.Peralta; MatildeS.Beresi

    2004-01-01

    The “9th International Symposium on the Ordovician System, 7th International Graptolite Conference & Field Meeting of the International Subcommission on Silurian Stratigraphy” commenced on August 12,2003, by receiving in San Juan City to all participants of the pre-symposia field trip through the Precordillera of Mendoza and San Juan provinces, western Argentina. On August 13, the field trip began with the purpose to show significant Lower Paleozoic outcrops from diverse settings of the Precordillera geological province. This fivedays excursion was led by Drs. S. H. Peralta.

  7. A review of the Late Cambrian (Furongian) palaeogeography in the western Mediterranean region, NW Gondwana

    Science.gov (United States)

    Álvaro, J. Javier; Ferretti, Annalisa; González-Gómez, Cristina; Serpagli, Enrico; Tortello, M. Franco; Vecoli, Marco; Vizcaïno, Daniel

    2007-11-01

    The Cambrian-Ordovician transition of the western Mediterranean region (NW Gondwana) is characterized by the record of major erosive unconformities with gaps that range from a chronostratigraphic stage to a series. The hiatii are diachronous and involved progressively younger strata along the Gondwanan margin, from SW (Morocco) to NE (Montagne Noire). They can be related to development of a multi-stage rifting (further North), currently connected to the opening of the Rheic Ocean, and concomitant erosion on southern rift shoulders. The platforms of this margin of Gondwana occupied temperate-water, mid latitudes and were dominated by siliciclastic sedimentation, while carbonate factories were only episodically active in the Montagne-Noire platform. The Upper Cambrian is devoid of significant gaps in the southern Montagne Noire and the Iberian Chains. There, the sedimentation took place in a transgressive-dominated depositional system, with common offshore deposits and clayey substrates, and was bracketed by two major regressive trends. The Late Cambrian is also associated with the record of volcanic activity ( e.g., in the Cantabrian and Ossa-Morena zones, and the northern Montagne Noire), and widespread development of a tectonic instability that led to the episodic establishment of palaeotopographies and record of slope-related facies associations. Several immigration events are recognized throughout the latest Middle Cambrian, Late Cambrian and Tremadocian. The trilobites show a stepwise replacement of Acado-Baltic-type families ( e.g., the conocoryphid-paradoxidid-solenopleurid assemblage) characterized by: (i) a late Languedocian (latest Middle Cambrian) co-occurrence of Middle Cambrian trilobite families with the first anomocarid, dorypygid and proasaphiscid invaders; (ii) a Late Cambrian immigration replacing previous faunas, composed of trilobites (aphelaspidids, catillicephalids, ceratopygids, damesellids, eulomids, idahoiids, linchakephalids, lisariids

  8. Coping – Late Side Effects

    Science.gov (United States)

    Cancer treatment can cause late side effects that may not show up for months or years after treatment. These late effects may include heart and lung problems, bone loss, eye and hearing changes, lymphedema, and other problems

  9. Late-modern hipsters

    DEFF Research Database (Denmark)

    Andersen, Bjørn Schiermer

    2014-01-01

    The article deals with the cultural significance of a new figure in late-modern Western culture: the hipster. The current hipster culture, so I argue, can be used as a magnifying glass that makes impending changes to our conception of culture and of cultural development visible. It ushers in broa...... redemptive gesture toward the objects of the recent past and its predilection for irony. The article seeks to unfold hipster culture and sociality in an ongoing dialogue with sociological theory in general and conventional ways of thinking subculture in particular....

  10. Late-onset hypogonadism

    Directory of Open Access Journals (Sweden)

    Piotr Dudek

    2017-06-01

    Full Text Available In Poland, the number of men over the age of 50 years exceeds 6 million. It is estimated that about 2-6% of this population develops symptoms of late-onset hypogonadism (LOH. In men, testosterone deficiency increases slightly with age. LOH is a clinically and biochemically defined disease of older men with serum testosterone level below the reference parameters of younger healthy men and with symptoms of testosterone deficiency, manifested by pronounced disturbances of quality of life and harmful effects on multiple organ systems. Testosterone replacement therapy may give several benefits regarding body composition, metabolic control, and psychological and sexual parameters.

  11. REE Compositions of Lower Ordovician Dolomites in Central and North Tarim Basin, NW China: A Potential REE Proxy for Ancient Seawater

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuefeng; HU Wenxuan; JIN Zhijun; ZHANG Juntao; QIAN Yixiong; ZHU Jingquan; ZHU Dongya; WANG Xiaolin; XIE Xiaomin

    2008-01-01

    Rare earth dement compositions of Lower Ordovician dolomites in the Central and Northern Tarim Basin are studied. Most dolomite samples are more or less contaminated by clay minerals. Their rare earth element compositions have been consequently changed, showing both seawater-like and non-seawater-like features. The clay contamination should be disposed before the REE data are used. Through ICP-MS and ICP-AES analyses, the REE features are well documented. The clay contamination is quantitatively determined by microscopic investigation, trace elements and REE contents. The dolomites, at least in the Tarim Basin, are thought to be pure when their total LREE contents are less than 3x10-6. Through comparison, the pure dolomites show similarities in REE patterns but differences in REE contents with co-existing pure limestone, which indicates that dolomitization may slightly change the REE compositions. Nevertheless, whatever the change is, the pure dolomites may act as a potential REE proxy for Ordovician seawater, which would be significant for ancient massive dolomite strata that lack limestone.

  12. A swollen crinoid pluricolumnal from the Upper Ordovician of northern Kentucky, USA: the oldest record of an amorphous paleopathologic response in Crinoidea?

    Directory of Open Access Journals (Sweden)

    James R. Thomka

    2014-12-01

    Full Text Available Swollen or otherwise malformed crinoid remains are relatively common in the Phanerozoic. However, published reports typically describe swellings associated with a discrete pit, boring, embedment structure or encruster, and, moreover, are overwhelmingly from Silurian or younger strata. Here, the rare occurrence of an amorphously swollen crinoid pluricolumnal is described from the Upper Ordovician (Katian Grant Lake Formation of north-central Kentucky, USA. This represents one of the oldest examples of crinoid malformation potentially resulting from interaction with a parasite or epibiont, one of the oldest examples of swelling in a crinoid column, and likely represents the oldest record of amorphous swelling. The pluricolumnal is morphologically generalized, making definitive identification difficult. Potential candidates include the diplobathrid camerate Pycnocrinus and the large, morphologically aberrant disparid Anomalocrinus. Regardless, if generated by an antagonistic biotic interaction, this specimen seems to support the hypothesis that crinoids with large calyxes and relatively complex arm morphologies were preferentially utilized as hosts for parasites and commensals over crinoids with simpler morphologies in the Ordovician.

  13. The GSSP of the Second (Upper) Stage of the Lower Ordovician Series: Diabasbrottet at Hunneberg, Province of Vaeistergoetland, Southwestern Sweden

    Institute of Scientific and Technical Information of China (English)

    StigM.Bergstroem; AnitaLoefgren; JoergMaletz

    2004-01-01

    Diabasbrottet, selected by the International Subcommisson on Ordovician Stratigraphy and in 2002 ratified by the International Commission on Stratigraphy as the GSSP of the Second (Upper) Stage of the Lower Ordovician, is located on the Hunneberg Mountain in southwestern Sweden. The stratigraphic succession represents an outer shelf environment near the Baltic Shield margin. The shale-dominated, biostratigraphically complete, richly fossiliferous boundary interval is completely exposed in a disused quarry. The GSSP is in the lower TФyen Shale 2.1 m above the top of the Cambrian and is marked by the first appearance of the graptolite Tetragraptus approximatus Nicholson. The boundary interval contains a diverse graptolite fauna and biostratigraphically diagnostic conodonts and trilobites that make it possible to define the boundary in terms of zone schemes based on these groups. In this respect, the Diabasbrottet and nearby sections are unique in the world among described localities having this boundary interval. Based on the appearance of T. approximatus, the base of the Second Stage can be identified in many graptolitiferous successions round the world but this level is currently more difficult to recognize precisely in some carbonate sequences outside Baltoscandia. We propose the Second Stage be called the Floan Stage. It is named for the Village of Flo, which is situated about 5 km southeast of the GSSP.

  14. Petrologic,geochemical characteristics and origin of the Lower Ordovician dolomite in Yubei area%玉北地区下奥陶统白云岩岩石学、地球化学特征及成因

    Institute of Scientific and Technical Information of China (English)

    黄擎宇; 张哨楠; 叶宁; 李映涛

    2014-01-01

    The petrologic ,geochemical characteristics and origin of the Lower Ordovician dolomite in Yubei area were inves -tigated through the analysis of the cores ,thin-sections,SEM,cathode luminescence ,trace element ,C-O isotope and micro-thermometry of fluid inclusions .The following results were obtained .Matrix dolomites are of two types:fine crystalline ,euhe-dral-subhedral dolomite and fine to coarse crystalline ,anhedral dolomite with saddle fillings .The origin of dolomite is close-ly related to crystal texture ( nonplanar anhedral ,planar euhedral/subhedral ) instead of crystal size .The fine crystalline ,eu-hedral-subhedral dolomite has high Sr and low Fe-Mn content ,and C and O isotope composition similar to that of seawater in Early Ordovician .So this type of dolomite was overall the product of low-temperature dolomitization associated with the Ordovician seawater during the early stage of shallow burial .In contrast ,the fine to coarse crystalline ,anhedral dolomite has low Sr,relatively high Fe and Mn content and more negative O isotope value .And its fluid inclusion microthermometry re-sult suggests that it has high homogenization temperature and salinity .Combined with the regional tectonic background ,it is believed that this type of dolomite was primarily the product of high -temperature dolomitization during late stage of shallow burial to moderate burial ,and was locally transformed by hydrothermal fluids from marine-sourced saline water in formation . Moreover ,there are two stages of saddle dolomite fillings:one is coeval with the matrix dolomite of hydrothermal dolomitiza-tion origin and the other may be associated with the thermal fluid post -magmatic activity during the Permian .%通过岩心、薄片、扫描电镜、阴极发光、微量元素、同位素和包裹体测温等分析手段,对玉北地区下奥陶统白云岩岩石学特征、地球化学特征及成因进行研究。结果表明,该区白云岩主要由细晶、自形-半

  15. New insights from U Pb zircon dating of Early Ordovician magmatism on the northern Gondwana margin: The Urra Formation (SW Iberian Massif, Portugal)

    Science.gov (United States)

    Solá, A. R.; Pereira, M. F.; Williams, I. S.; Ribeiro, M. L.; Neiva, A. M. R.; Montero, P.; Bea, F.; Zinger, T.

    2008-12-01

    The Central Iberian-Ossa-Morena transition zone (SW Iberian Massif) represents a segment of the northern Gondwana margin with a long geodynamic evolution, characterized by the superposition of Cadomian and Variscan events. The Early Ordovician is mainly represented by porphyritic felsic volcaniclastic rocks (the Urra Formation) that pass up into a siliciclastic sediments typical of the Central Iberian Zone (Lower Ordovician Armorican Quartzite Formation). The Urra Formation unconformably overlies the previously deformed and metamorphosed Ediacaran sediments of the Série Negra (with Ossa-Morena Zone paleogeographic affinity). New SHRIMP zircon data obtained from the Urra Formation volcaniclastic rocks indicate an Early Ordovician age ( 206Pb/ 238U ages ranging from 494.6 ± 6.8 Ma to 488.3 ± 5.2 Ma) for this magmatic event. The inherited zircon cores indicate the presence of multicycle protoliths with different Precambrian ages: Neoproterozoic (698-577 Ma), Paleoproterozoic (2.33 Ga) and Paleoarchean (3.2-3.3 Ga). There is a noticeable lack of Meso- to Neoarchean and Mesoproterozoic ages. The data support the hypothesis that the volcaniclastic rocks were derived by partial melting of Cadomian basement (linked to a West African Craton provenance). The Urra Formation volcaniclastic rocks have rhyolitic to dacitic compositions, are peraluminous and similar to calc-alkaline high-K series suites elsewhere. Isotopic signatures present a wide range of values ( 87Sr/ 86Sr) t = 0.7085-0.7190, more restricted ɛNd t (- 2.65 to - 0.35) and δ18O = 9.63-10.34‰, compatible with magmas derived from crustal rocks, including portions of the lower crust. Some samples show disturbance of the Rb-Sr system as shown by unrealistic values for ( 87Sr/ 86Sr) t < 0.703, probably due to Variscan deformation and metamorphism. The volcaniclastic rocks with a significant sedimentary contribution (upper unit) are distinguished from the others by the lowest values of ɛNd t (- 5.53 to - 4

  16. Ordovician and Silurian Phi Kappa and Trail Creek formations, Pioneer Mountains, central Idaho; stratigraphic and structural revisions, and new data on graptolite faunas

    Science.gov (United States)

    Dover, James H.; Berry, William B.N.; Ross, Reuben James

    1980-01-01

    Recent geologic mapping in the northern Pioneer Mountains combined with the identification of graptolites from 116 new collections indicate that the Ordovician and Silurian Phi Kappa and Trail Creek Formations occur in a series of thrust-bounded slices within a broad zone of imbricate thrust faulting. Though confirming a deformational style first reported in a 1963 study by Michael Churkin, our data suggest that the complexity and regional extent of the thrust zone were not previously recognized. Most previously published sections of the Phi Kappa and Trail Creek Formations were measured across unrecognized thrust faults and therefore include not only structural repetitions of graptolitic Ordovician and Silurian rocks but also other tectonically juxtaposed lithostratigraphic units of diverse ages as well. Because of this discovery, the need to reconsider the stratigraphic validity of these formations and their lithology, nomenclature, structural distribution, facies relations, and graptolite faunas has arisen. The Phi Kappa Formation in most thrust slices has internal stratigraphic continuity despite the intensity of deformation to which it was subjected. As revised herein, the Phi Kappa Formation is restricted to a structurally repeated succession of predominantly black, carbonaceous, graptolitic argillite and shale. Some limy, light-gray-weathering shale occurs in the middle part of the section, and fine-grained locally pebbly quartzite is present at the base. The basal quartzite is here named the Basin Gulch Quartzite Member of the Phi Kappa. The Phi Kappa redefined on a lithologic basis represents the span of Ordovician time from W. B. N. Berry's graptolite zones 2-4 through 15 and also includes approximately 17 m of lithologically identical shale of Early and Middle Silurian age at the top. The lower contact of the formation as revised is tectonic. The Phi Kappa is gradationally overlain by the Trail Creek Formation as restricted herein. Most of the coarser

  17. Geochemistry and jasper beds from the Ordovician Løkken ophiolite, Norway: origin of proximal and distal siliceous exhalites

    Science.gov (United States)

    Grenne, Tor; Slack, John F.

    2005-01-01

    Stratiform beds of jasper (hematitic chert), composed essentially of SiO2 (69-95 wt %) and Fe2O3 (3-25 wt %), can be traced several kilometers along strike in the Ordovician L??kken ophiolite, Norway. These siliceous beds are closely associated with volcanogenic massive sulfide (VMS) deposits and are interpreted as sea-floor gels that were deposited by fallout from hydrothermal plumes in silica-rich seawater, in which plume-derived Fe oxyhydroxide particles promoted flocculation and rapid settling of large (???200 ??m) colloidal particles of silica-iron oxyhydroxide. Concentrations of chalcophile elements in the jasper beds are at the parts per million level implying that sulfide particle fallout was insignificant and that the Si-Fe gel-forming plumes were mainly derived from intermediate- (100??-250??C) to high-temperature (>250??) white smoker-type vents with high Fe/S ratios. The interpreted setting is similar to that of the Lau basin, where high-temperature (280??-334??C) white smoker venting alternates or overlaps with sulfide mound-forming black smoker venting. Ratios of Al, Sc, Th, Hf, and REE to iron are very low and show that the detrital input was lifetime of 200 years or less. The lack of thick jasper beds near the L??kken VMS orebody, which is larger than the H??ydal orebody by more than two orders of magnitude, probably reflects a shift to anoxic conditions during L??kken mineralization. This environment limited oxidation of iron in the hydrothermal plume and formation of the ferric oxyhydroxides necessary for the flocculation of silica and sea-floor deposition of the gel precursor of the jasper beds. Distal pyritic and iron-poor cherts are more common than jasper in ancient VMS-hosting sequences. The origin of these other types of siliceous exhalite is enigmatic but at least in some cases involved sulfidation, reduction to magnetite, or dissolution of the original ferric iron in precursor Si-rich gels, either by hydrothermal or diagenetic processes

  18. Provenance variability along the Early Ordovician north Gondwana margin: Paleogeographic and tectonic implications of U-Pb detrital zircon ages from the Armorican Quartzite of the Iberian Variscan belt

    NARCIS (Netherlands)

    Shaw, J.; Gutiérrez-Alonso, G.; Johnston, S.T.; Pastor-Galán, D.

    2014-01-01

    Detrital zircon laser ablation–inductively coupled plasma–mass spectrometry U-Pb age data from the Lower Ordovician Armorican Quartzite (deformed passive margin strata of Gondwanan affinity) of the Iberian Massif are presented herein. The S-shaped coupled Iberian oroclines defined within these zones

  19. The Global Stratotype Section and Point(GSSP) for the base of the Katian Stage of the Upper Ordovician Series at Black Knob Ridge,Southeastern Oklahoma,USA

    Institute of Scientific and Technical Information of China (English)

    Daniel Goldman; Stephen A.Leslie; Jaak N(o)lvak; Seth Young; Stig M.Bergstr(o)m; Warren D.Huff

    2007-01-01

    @@ The Global Boundary Stratotype Section and Point (GSSP)for the Katian Stage of the Upper Ordovician Series is defined as the 4.0 m-level above the base of the Bigfork Chert in the Black Knob Ridge section,southeastern Oklahoma.

  20. Never too late.

    Science.gov (United States)

    1996-11-01

    Motivated by the belief that education has been central to Japan's economic success, Japan International Cooperation Agency (JICA) promotes universal access to quality basic education. In developing countries, school children rarely learn science through experiments. A new JICA training course, the Science Experiment in Primary Education, involved teacher trainers from Bangladesh, Myanmar, Pakistan, and Sri Lanka. Physics, chemistry, biology, geology, and astronomy experiments that require simple, inexpensive materials were taught. Another JICA project in Satkhira, Bangladesh, sought to raise the economic status of women enrolled in a dressmaking program through a year-long evening literacy class at three sites. Elementary school diplomas (available with proof to a local teacher of basic literacy and minimal arithmetic skills) are required in Bangladesh to apply for nongovernmental organization-initiated vocational schools and loans to start businesses in areas such as dressmaking, agriculture, and livestock raising. By late 1993, the female literacy program had expanded to 18 villages.

  1. Late-Modern Symbolism

    DEFF Research Database (Denmark)

    Andersen, Bjørn Schiermer

    2015-01-01

    Through analysis of key texts, I seek to demonstrate the explanative potential of Durkheim’s sociology of religion in the present context. I critically readdress the idea, found in his early work, that modernity is characterized by a rupture with pre-modern forms of solidarity. First, I investigate...... the ways in which Durkheim sets up a stark distinction between the pre-modern and the modern in his early work, and how this distinction is further cemented by his orthodox critique of the modern economy and its negative effects on social life. Second, I show how another timeless and positive understanding...... of “mechanical” solidarity is to be found behind the “symbolist” template crystalizing in Durkheim’s late work. Third, I develop this template for a modern context by critically addressing and removing other obstacles and prejudices on Durkheim’s part....

  2. Eustatic and far-field tectonic control on the development of an intra-platform carbonate-shoal complex: upper tongue of the Tanglewood Member, Upper Ordovician Lexington Limestone, central Kentucky, U.S.A.

    Science.gov (United States)

    Koirala, Dibya Raj; Ettensohn, Frank R.; Clepper, Marta L.

    2016-11-01

    The Lexington or Trenton Limestone is an Upper Ordovician (Chatfieldian-Edenian; upper Sandbian-lower Katian), temperate-water unit, averaging about 60-m thick, that was deposited in relatively shallow waters across the Lexington Platform in east-central United States during the Taconian Orogeny. Lexington/Trenton shallow-water deposition ended across most of the platform in late Chatfieldian time and from that point deepened upward into the more shale-rich Clays Ferry, Point Pleasant and Kope formations due to apparent sea-level rise. In central Kentucky, however, deposition of the Lexington Limestone continued into early Edenian time and includes up to 50 m of additional coarse calcarenites and calcirudites at the top, which form the Tanglewood buildup and reflect locally regressive conditions, apparently related to local structural uplift. Consequently, in central Kentucky, the Lexington is more than 100-m thick, and Lexington deposition on the buildup continued into early Edenian time as an intra-platform shoal complex that tongues out into deeper-water units in all directions. In an attempt to understand how this shoal complex developed, we examined the last major body of coarse skeletal sands in the central Kentucky Lexington Limestone, the upper tongue of the Tanglewood Member, a 12-m-thick succession of fossiliferous calcarenite and calcirudite that occurs across an area of 5200 km2 near the center of the Lexington Platform. Although relatively homogeneous, the upper Tanglewood is divisible into five, small-scale, fining-upward, sequence-like cycles, which contain prominent, widespread deformed horizons. Facies analysis indicates that four lithofacies, which reflect distinct depositional environments, comprise the sequences across the shoal complex. Lithofacies were correlated across the shoal complex by integrating cyclicity and widespread deformed horizons in order to delineate the locations of major depositional environments. Facies analysis shows that

  3. Evidence of the latest Ordovician sea level drop on Avalonia in the Condroz Inlier, Belgium, and dating with chitinozoans by comparison with the Ashgill type area, Cautley District, U.K.

    Science.gov (United States)

    Vanmeirhaeghe, J.; Vandenbroucke, T.; Verniers, J.

    2003-04-01

    Recently, two conglomerate levels were discovered in the latest Ordovician Génicot Formation in the Puagne area, western Condroz Inlier, Belgium (Herbosch et al. 2001; in press). In the middle of the latter formation, a lower matrix-supported conglomerate approximately 1.2 m thick and with an erosional base is separated by 5.5 m of mudstone and siltstone from a second pebble-supported conglomerate of 2.05 m thick. A local chitinozoan biozonation places both conglomerates in the late Ashgill (stage 6). The sediments of the unit are supposed to be deposited on a moderately deep shelf. However, the sudden presence of the two conglomerates, the lower one with an erosional base, is interpreted as the sedimentological response to the sea level drop associated with the Hirnantian glaciation and deglaciation event (Vanmeirhaeghe &Verniers, submitted). This poster presents the results of a comparison of the chitinozoan biozonation of the Puagne area with that of the Ashgill type area in the Howgill Fells inliers, northern England, U.K. This resulted in a more accurate dating of the two conglomerates and of the complete Génicot and the underlying Fosses Formations in Belgium. A summary of all evidence of the Hirnantian glaciation on the Avalonia microcontinent is shown. HERBOSCH, A., VERNIERS, J., DEBACKER, T., BILLIAERT, B., DE SCHEPPER, S., BELMANS, M. (2001). The Lower Palaeozoic stratigraphy and sedimentology of the Brabant Massif in the Dyle and Orneau valleys and of the Condroz Inlier at Fosses: an excursion guidebook. Pre-symposium excursion of the International Symposium on "Early Palaeozoic Palaeogeographies and Biogeographies of Western Europe and North Africa", Lille USTL, September 22-26, 2001, 1-77. HERBOSCH, A., VERNIERS, J., DEBACKER, T., BILLIAERT, B., DE SCHEPPER, S., BELMANS, M. (2002). The Lower Palaeozoic stratigraphy and sedimentology of the Brabant Massif in the Dyle and Orneau valleys and of the Condroz Inlier at Fosses: an excursion guidebook

  4. Rapid sea-level change in the Late Guadalupian (Permian) on the Tethyan side of South China: litho- and biostratigraphy of the Chaotian section in Sichuan.

    Science.gov (United States)

    Isozaki, Yukio; Yao, Jianxin; Ji, Zhangshen; Saitoh, Masafumi; Kobayashi, Noritada; Sakai, Harutaka

    2008-01-01

    The Capitanian (Late Guadalupian) Maokou Formation at Chaotian in northern Sichuan, South China, is composed mainly of shallow marine shelf carbonates deposited on the Tethyan side of South China. By detailed field mapping and scientific drilling, we newly found out unique fossil assemblages and a sharp lithologic change in the upper part of the Maokou Formation. The main part of the Maokou Formation (over 130 m thick) is composed of algal packstone with Wordian-Capitanian large-tested fusulines, rugose corals and other sessile benthos, whereas the Uppermost Member (13 m thick) is composed of black limy mudstone/chert with Capitanian offshore biota (ammonoids, radiolarians, and conodonts). The topmost Capitanian conodont zones are missing; however, the Maokou Formation is disconformably overlain by 260+/-4 Ma volcanic ash (Wangpo bed) and the Early Lopingian Wujiaping Formation with plant-bearing coaly mudstone and shallow marine carbonates (packstone). The newly identified facies change indicates that northern Sichuan has experienced rapid sea-level changes in the late Guadalupian, i.e., first a transgression in the mid-Capitanian and then a regression across the Guadalupian-Lopingian boundary. As the end-Guadalupian is characterized by a global regression, such a volatile sea-level fluctuation, in particular the sea-level rise, is unique to the Tethyan side of South China. The newly recognized relatively deep-water late Guadalupian sequence adds new paleo-environmental information and further provides a paleotectonic interpretation of the low-latitude eastern Tethyan margin immediately before the end-Guadalupian mass extinction.

  5. 塔里木盆地塔中地区下奥陶统白云岩成因%Genesis of Lower Ordovician Dolomite in Central Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    李鹏春; 陈广浩; 曾乔松; 易金; 胡罡

    2011-01-01

    塔里木盆地塔中地区下奥陶统白云岩广泛发育,岩石类型复杂多样,主要包括结晶白云岩、残余颗粒白云岩、残余灰质白云岩、藻云岩、亮边雾心白云岩、环带白云岩及少量膏云岩等结构类型。白云岩交代现象明显,δ18O普遍为中—高负值(-3.2‰~-8.7‰);δ13C值基本为低中负值(-3‰~-0.77‰),Z值大多集中在118~123之间,成岩温度大部分集中于36~51℃范围,属于低温白云岩。白云岩具有低Mg/Ca比值,而Fe/Mn比值变化较大;白云石成分显示高铁白云石和低铁白云石之分;Sr同位素组成(0.708 8~0.709 7)普遍与海水锶同位素组成相当,但也存在个别具有较高的87Sr/86Sr比值(0.710 1~0.710 9)。结合塔中地区奥陶系古地理演变特征,白云岩化类型可划分为准同生期白云石化作用和埋藏白云石化作用。准同生期白云石化作用发生于海底(主要是潮间)成岩环境,主要是在潮坪环境或滩相环境中,其白云岩形成温度较低,具低87Sr/86Sr比值,白云石单矿物具低Fe含量;而埋藏白云岩化存在两种模式,一种为早期浅埋藏过程中的卤水回流模式,其白云岩形成温度亦较低,具高87Sr/86Sr比值,白云石单矿物具高Fe含量;另一类发生于还原性较强晚期埋藏较深的成岩环境,在埋藏阶段白云岩化程度得到进一步加强和调整,其白云岩形成温度较高,白云石捕获的包裹体均一温度较高,盐度较低。%Lower Ordovician dolomites in the central Tarim basin are of various types and extensively distributed.Seven dolostone types could be documented based on fabrics and structures,which are crystalline dolomite,residual-grain dolomite,residual calcite dolomite,algal dolomite,cloudy centers and clear rims dolomite,clitellum dolomite and gypes dolomite.It’s characterised by middle-high δ18O negative value(-3.2%~-8.7‰),low-middle δ13C negative value(-3%~-0.77

  6. A reference region for the Ordovician-Silurian boundary: the Oued In Djerane, Algerian SaharaUne région de référence pour la limite Ordovicien-Silurien : l'Oued In Djerane, Sahara algérien

    Science.gov (United States)

    Legrand, Philippe

    2000-01-01

    The melting chronology of the Latest Ordovician inlandsis takes on a particular importance in northern Gondwana. A continuous sequence of Diplograptid range zones has been defined from outcrops in the Oued In Djerane, but its comparison with the sequence observed in the stratotype of the Silurian-Ordovician boundary is problematic because of the endemic character of the Saharan species. Moreover, some difficulties are linked to the definition of the Ordovician-Silurian boundary, which, in the Algerian Sahara, probably lies in the Pseudorthograptus (?) kiliani zone. A definite regional diachronism in the melting of the ice-cap has also been confirmed.

  7. Late Carboniferous to Late Permian carbon isotope stratigraphy

    DEFF Research Database (Denmark)

    Buggisch, Werner; Krainer, Karl; Schaffhauser, Maria

    2015-01-01

    An integrated study of the litho-, bio-, and isotope stratigraphy of carbonates in the Southern Alps was undertaken in order to better constrain δ13C variations during the Late Carboniferous to Late Permian. The presented high resolution isotope curves are based on 1299 δ13Ccarb and 396 δ13Corg a...

  8. End Ordovician extinctions

    DEFF Research Database (Denmark)

    Harper, David A. T.; Hammarlund, Emma; Rasmussen, Christian M. Ø.

    2014-01-01

    across a range of water depths. In all about 85% of marine species were removed. Proposed kill mechanisms for the first phase have included glaciallyinduced cooling, falling sea level and chemical recycling in the oceans, but a general consensus is lacking. The second phase is more clearly linked to near...

  9. Illusory Late Heavy Bombardments.

    Science.gov (United States)

    Boehnke, Patrick; Harrison, T Mark

    2016-09-27

    The Late Heavy Bombardment (LHB), a hypothesized impact spike at ∼3.9 Ga, is one of the major scientific concepts to emerge from Apollo-era lunar exploration. A significant portion of the evidence for the existence of the LHB comes from histograms of (40)Ar/(39)Ar "plateau" ages (i.e., regions selected on the basis of apparent isochroneity). However, due to lunar magmatism and overprinting from subsequent impact events, virtually all Apollo-era samples show evidence for (40)Ar/(39)Ar age spectrum disturbances, leaving open the possibility that partial (40)Ar* resetting could bias interpretation of bombardment histories due to plateaus yielding misleadingly young ages. We examine this possibility through a physical model of (40)Ar* diffusion in Apollo samples and test the uniqueness of the impact histories obtained by inverting plateau age histograms. Our results show that plateau histograms tend to yield age peaks, even in those cases where the input impact curve did not contain such a spike, in part due to the episodic nature of lunar crust or parent body formation. Restated, monotonically declining impact histories yield apparent age peaks that could be misinterpreted as LHB-type events. We further conclude that the assignment of apparent (40)Ar/(39)Ar plateau ages bears an undesirably high degree of subjectivity. When compounded by inappropriate interpretations of histograms constructed from plateau ages, interpretation of apparent, but illusory, impact spikes is likely.

  10. δ13C chemostratigraphy of the Middle and Upper Ordovician succession in the Tartu-453 drillcore, southern Estonia, and the significance of the HICE

    Directory of Open Access Journals (Sweden)

    Heikki Bauert

    2014-12-01

    Full Text Available The δ13C isotope data from the Tartu-453 core section in southern Estonia enabled creation of a continuous Ordovician carbon isotope record, ranging from the Floian to the end of the Hirnantian. Five positive δ13C excursions and one negative δ13C excursion were recognized. Most of the positive excursions correspond to those defined on the Baltoscandian carbon isotope chemostratigraphic scheme, except for the Paroveja and Rakvere ICEs which are not well expressed in the Tartu-453 curve. Besides the positive δ13C excursions, a distinctive negative δ13C excursion, the Lower Sandbian NICE, was recorded in the Tartu-453 succession. The well-expressed HICE extends about 10 m higher than the traditional Ordovician–Silurian boundary (between the Porkuni and Juuru regional stages into the Juuru Regional Stage, suggesting that the Ordovician–Silurian boundary is positioned significally higher than traditionally suggested for the East Baltic area.

  11. Recent casualties of late globalization

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    2016-01-01

    In this essay I will expand my thoughts on universities as ‘late globalizers’ and the impact ‘being late’ has on university internationalization or globalization activities. In my earlier essay I viewed universities as ‘late globalizers’ and briefly introduced the impact of being ‘late’, e...

  12. Recent casualties of late globalization

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    2016-01-01

    In this essay I will expand my thoughts on universities as ‘late globalizers’ and the impact ‘being late’ has on university internationalization or globalization activities. In my earlier essay I viewed universities as ‘late globalizers’ and briefly introduced the impact of being ‘late’, e.g., wi...

  13. Arc-continent collision and the formation of continental crust: A new geochemical and isotopic record from the Ordovician Tyrone Igneous Complex, Ireland

    Science.gov (United States)

    Draut, Amy E.; Clift, Peter D.; Amato, Jeffrey M.; Blusztajn, Jerzy; Schouten, Hans

    2009-01-01

    Collisions between oceanic island-arc terranes and passive continental margins are thought to have been important in the formation of continental crust throughout much of Earth's history. Magmatic evolution during this stage of the plate-tectonic cycle is evident in several areas of the Ordovician Grampian-Taconic orogen, as we demonstrate in the first detailed geochemical study of the Tyrone Igneous Complex, Ireland. New U-Pb zircon dating yields ages of 493 2 Ma from a primitive mafic intrusion, indicating intra-oceanic subduction in Tremadoc time, and 475 10 Ma from a light rare earth element (LREE)-enriched tonalite intrusion that incorporated Laurentian continental material by early Arenig time (Early Ordovician, Stage 2) during arc-continent collision. Notably, LREE enrichment in volcanism and silicic intrusions of the Tyrone Igneous Complex exceeds that of average Dalradian (Laurentian) continental material that would have been thrust under the colliding forearc and potentially recycled into arc magmatism. This implies that crystal fractionation, in addition to magmatic mixing and assimilation, was important to the formation of new crust in the Grampian-Taconic orogeny. Because similar super-enrichment of orogenic melts occurred elsewhere in the Caledonides in the British Isles and Newfoundland, the addition of new, highly enriched melt to this accreted arc terrane was apparently widespread spatially and temporally. Such super-enrichment of magmatism, especially if accompanied by loss of corresponding lower crustal residues, supports the theory that arc-continent collision plays an important role in altering bulk crustal composition toward typical values for ancient continental crust. ?? 2009 Geological Society of London.

  14. Late-life attachment.

    Science.gov (United States)

    Freitas, Mélanie; Rahioui, Hassan

    2017-03-01

    Old age is likely to cause a crisis in one's life because of the vulnerabilities it brings up, acting as stressful elements disrupting the elder's feeling of security. It leads to the activation of what is called his attachment system, consisting in attachment styles and interpersonal emotional regulation strategies. To recover a higher sense of safety, the elder would refer to his attachment figures, that is to say closed people paying attention to him, showing towards him availability and consideration. However older adults particularly see their tolerance threshold lowered, regarding an accumulation of losses (true or symbolic) and stressful events within their lifetime. In a psychological and organic exhaustion phenomenon, the risk is to wear out the interpersonal emotional regulation strategies. These are as much vulnerabilities that may increase psychiatric decompensation, including depression. To resolve the tension of this period and to found a necessary secure feeling, the elder will have to redesign the attachment links previously settled and proceed to adjustments to this new context. The need of relational closeness comes back in the elders' attachment behaviour, counting on attachment figures not only to help their loneliness or dependency, but essentially to support them in a narcissist and affective way. That is why attachment theory enlightens the late life period, such as the new challenges older adults have to face. Many studies recognize its value in understanding the transition to old age, but without proposing conceptualization. We aim first to focus on attachment conception to say how much it is relevant with elderly, and then to describe specific terms of attachment within this population in order to better understand those patients. To finish, we must think about new therapeutic proposals taking into consideration the attachment perspective for a better understanding of old age transition.

  15. Vaginal bleeding in late pregnancy

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000627.htm Vaginal bleeding in late pregnancy To use the sharing features ... the blood from soaking your clothes. What Causes Bleeding Later in Pregnancy? When labor begins, the cervix ...

  16. Late and chronic Lyme disease.

    Science.gov (United States)

    Donta, Sam T

    2002-03-01

    This article reviews the late and chronic manifestations of Lyme disease. Special attention is given to the chronic manifestations of the disease, detailing its pathogenesis, clinical spectrum, and laboratory criteria for the diagnosis. Based on experimental evidence and experience, approaches to the successful treatment of the late and chronic disease are outlined. Much additional work is needed to improve the understanding of the underlying pathophysiology of the disease, its diagnosis and treatment.

  17. Late prematurity: a systematic review

    Directory of Open Access Journals (Sweden)

    Luís Carlos Machado Júnior

    2014-06-01

    Full Text Available Objective: this study aimed to review the literature regarding late preterm births (34 weeks to 36 weeks and 6 days of gestation in its several aspects. Sources: the MEDLINE, LILACS, and Cochrane Library databases were searched, and the references of the articles retrieved were also used, with no limit of time. Data synthesis: numerous studies showed a recent increase in late preterm births. In all series, late preterm comprised the majority of preterm births. Studies including millions of births showed a strong association between late preterm birth and neonatal mortality. A higher mortality in childhood and among young adults was also observed. Many studies found an association with several neonatal complications, and also with long-term disorders and sequelae: breastfeeding problems, cerebral palsy, asthma in childhood, poor school performance, schizophrenia, and young adult diabetes. Some authors propose strategies to reduce late preterm birth, or to improve neonatal outcome: use of antenatal corticosteroids, changes in some of the guidelines for early delivery in high-risk pregnancies, and changes in neonatal care for this group. Conclusions: numerous studies show greater mortality and morbidity in late preterm infants compared with term infants, in addition to long-term disorders. More recent studies evaluated strategies to improve the outcomes of these neonates. Further studies on these strategies are needed.

  18. Late prematurity: a systematic review.

    Science.gov (United States)

    Machado Júnior, Luís Carlos; Passini Júnior, Renato; Rodrigues Machado Rosa, Izilda

    2014-01-01

    this study aimed to review the literature regarding late preterm births (34 weeks to 36 weeks and 6 days of gestation) in its several aspects. the MEDLINE, LILACS, and Cochrane Library databases were searched, and the references of the articles retrieved were also used, with no limit of time. numerous studies showed a recent increase in late preterm births. In all series, late preterm comprised the majority of preterm births. Studies including millions of births showed a strong association between late preterm birth and neonatal mortality. A higher mortality in childhood and among young adults was also observed. Many studies found an association with several neonatal complications, and also with long-term disorders and sequelae: breastfeeding problems, cerebral palsy, asthma in childhood, poor school performance, schizophrenia, and young adult diabetes. Some authors propose strategies to reduce late preterm birth, or to improve neonatal outcome: use of antenatal corticosteroids, changes in some of the guidelines for early delivery in high-risk pregnancies, and changes in neonatal care for this group. numerous studies show greater mortality and morbidity in late preterm infants compared with term infants, in addition to long-term disorders. More recent studies evaluated strategies to improve the outcomes of these neonates. Further studies on these strategies are needed. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  19. Late effects from hadron therapy

    Energy Technology Data Exchange (ETDEWEB)

    Blakely, Eleanor A.; Chang, Polly Y.

    2004-06-01

    Successful cancer patient survival and local tumor control from hadron radiotherapy warrant a discussion of potential secondary late effects from the radiation. The study of late-appearing clinical effects from particle beams of protons, carbon, or heavier ions is a relatively new field with few data. However, new clinical information is available from pioneer hadron radiotherapy programs in the USA, Japan, Germany and Switzerland. This paper will review available data on late tissue effects from particle radiation exposures, and discuss its importance to the future of hadron therapy. Potential late radiation effects are associated with irradiated normal tissue volumes at risk that in many cases can be reduced with hadron therapy. However, normal tissues present within hadron treatment volumes can demonstrate enhanced responses compared to conventional modes of therapy. Late endpoints of concern include induction of secondary cancers, cataract, fibrosis, neurodegeneration, vascular damage, and immunological, endocrine and hereditary effects. Low-dose tissue effects at tumor margins need further study, and there is need for more acute molecular studies underlying late effects of hadron therapy.

  20. Late effects from hadron therapy.

    Science.gov (United States)

    Blakely, Eleanor A; Chang, Polly Y

    2004-12-01

    Successful cancer patient survival and local tumor control from hadron radiotherapy warrant a discussion of potential secondary late effects from the radiation. The study of late-appearing clinical effects from particle beams of protons, carbon, or heavier ions is a relatively new field with few data. However, new clinical information is available from pioneer hadron radiotherapy programs in the USA, Japan, Germany and Switzerland. This paper will review available data on late tissue effects from particle radiation exposures, and discuss its importance to the future of hadron therapy. Potential late radiation effects are associated with irradiated normal tissue volumes at risk that in many cases can be reduced with hadron therapy. However, normal tissues present within hadron treatment volumes can demonstrate enhanced responses compared to conventional modes of therapy. Late endpoints of concern include induction of secondary cancers, cataract, fibrosis, neurodegeneration, vascular damage, and immunological, endocrine and hereditary effects. Low-dose tissue effects at tumor margins need further study, and there is need for more acute molecular studies underlying late effects of hadron therapy.

  1. Late Paleozoic fusulinids from Sonora, Mexcio: importance for interpretation of depositional settings, biogeography, and paleotectonics

    Science.gov (United States)

    Stevens, Calvin H.; Poole, Forrest G.; Amaya-Martínez, Ricardo

    2014-01-01

    Three sets of fusulinid faunas in Sonora, Mexico, discussed herein, record different depositional and paleotectonic settings along the southwestern margin of Laurentia (North America) during Pennsylvanian and Permian time. The settings include: offshelf continental rise and ocean basin (Rancho Nuevo Formation in the Sonora allochthon), shallow continental shelf (La Cueva Limestone), and foredeep basin on the continental shelf (Mina México Formation). Our data represent 41 fusulinid collections from 23 localities with each locality providing one to eight collections. Reworked fusulinids in the Middle and Upper Pennsylvanian part of the Rancho Nuevo Formation range in age from Desmoinesian into Virgilian (Moscovian-Gzhelian). Indigenous Permian fusulinids in the La Cueva Limestone range in age from middle or late Wolfcampian to middle Leonardian (late Sakmarian-late Artinskian), and reworked Permian fusulinids in the Mina México Formation range in age from early to middle Leonardian (middle-late Artinskian). Conodonts of Guadalupian age occur in some turbidites in the Mina México Formation, indicating the youngest foredeep deposit is at least Middle Permian in age. Our fusulinid collections indicate a hiatus of at least 10 m.y. between the youngest Pennsylvanian (Virgilian) rocks in the Sonora allochthon and the oldest Permian (middle Wolfcampian) rocks in the region. Most fusulinid faunas in Sonora show affinities to those of West Texas, New Mexico, and Arizona; however, some genera and species are similar to those in southeastern California. As most species are similar to those east of the southwest-trending Transcontinental arch in New Mexico and Arizona, this arch may have formed a barrier preventing large-scale migration and mixing of faunas between the southern shelf of Laurentia in northwestern Mexico and the western shelf in the southwestern United States. The Sonora allochthon, consisting of pre-Permian (Lower Ordovician to Upper Pennsylvanian) deep

  2. TWO NEW ORDOVICIAN TRILOBITE GENERA FROM WESTERN MARGINAL AREAS OF THE NORTH CHINA PLATFORM%华北地台西缘两个奥陶纪三叶虫新属

    Institute of Scientific and Technical Information of China (English)

    周志毅; 周志强

    2006-01-01

    @@ In connection with the preparation of a chapter of the monograph "Trilobite record of China" on the Ordovician trilobites, a large number of Chinese species were critically reviewed. Among others, two of them previously described from western marginal areas of the North China Platform respectively by Lu in Lu et al. (1976) as Bulbaspis ordosensis and by Zhou and Dean (1986) as Ischylophyma? zhiqiangi ought to be reassigned to new genera.

  3. Late sequelae of superficial irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hood, I.C.; Young, J.E.

    1984-10-01

    Superficial irradiation results in well recognized late sequelae including not only sclerosis and atrophy of skin and subcutaneous tissue, but also the development of benign and malignant tumors of skin and adjacent structures. The long latency between irradiation and its late effects allowed the early uncontrolled use of radiation treatment for benign conditions. The subsequent recognition of the causal relationship between tumors and previous irradiation has restricted its use to more appropriate purposes, although it is possible that it is still overused in some areas of dermatologic practice. Clinicians need to be aware of the time interval between irradiation and the development of its late sequelae, and the incidence of these sequelae. Appropriate irradiation exposure history should be a part of the evaluation of every patient.

  4. [Late-onset dysthymic states].

    Science.gov (United States)

    Siranchiev, M A

    2002-01-01

    Sixty patients with dysthymic states which had emerged in later age of 60-80 years were examined. Two clinical types of dysthymic states were described: anergic (20 patients) and hypothymic (40 patients). Different comorbid mental disorders--obsessive-phobic (14 cases), somatoform (10), personality deviations (20) and psycho-organic (7)--were found to be characteristic of late-onset dysthymic states. According to developmental features, late dysthymia was primary (first manifested in the elderly) and secondary (develops after several depressive episodes). In diagnostic terms, the former is considered as "dysthymia" (F34.1 ICD-10) and the latter--as "recurrent depressive disorder" (F33).

  5. Ordovician stratigraphic divisions and correlation of Maigaiti slope in Tarim Basin and its significance%塔里木盆地麦盖提斜坡奥陶纪地层划分对比及意义

    Institute of Scientific and Technical Information of China (English)

    刘忠宝; 张福顺; 高山林; 岳勇

    2016-01-01

    以碳同位素值的波动变化与沉积环境、海平面升降及地层界面突变等地质事件相对应为理论依据,开展碳同位素地层研究,建立了各组值域划分标准,解决碳酸盐岩地层缺乏标准生物化石情况下,地层归属难确定的问题。指出奥陶系自下而上碳同位素曲线呈现稳定-上升-正漂移的过程。其中,下统蓬莱坝组—鹰山组δ13C值范围为(-4.2~-0.2)×10-3,始终为负值;中统一间房组δ13C值范围为(-0.4~0.6)×10-3,以分布在零值附近为特征;上统恰尔巴克组—良里塔格组δ13C值范围(0.7~3.1)×10-3,均为正值。在此基础上,开展了巴楚典型露头剖面与麦盖提斜坡井下奥陶系碳同位素地层与岩石地层对比研究,提出麦盖提斜坡中部及东部断洼区发育上奥陶统,除东部断裂带外,普遍残存下奥陶统顶部泥晶灰岩段。%Based on the theory of corresponding relation between carbon isotope value fluctuation with sedi-mentary environment,sea level eustacy,formation interface mutation,etc,the authors study the stratigraphy by carbon isotopic method,and establish the classification standards for each unit,which solved the difficult problems on determining of the strata without index fossils in carbonate rocks.The Ordovician carbon isotopic curves present a process of stable-rising-positive drift in descending order.The δ1 3 C values vary from -4. 2 ×1 0 -3 to -0. 2 × 1 0 -3 in Lower Ordovician Penglaiba Formation and Yingshan Formation,characterized by the values below zero;from -0. 4 ×1 0 -3 to 0. 6 ×1 0 -3 in Middle Ordovician Yijianfang Formation,characterized by distributed near the zero value,and vary from 0. 7 ×1 0 -3 to 3. 1 ×1 0 -3 in Upper Ordovician Qiaerbake Formation and Lianglitage For-mation,featured by the values all above zero.On this basis,with the carbon isotopic standards,the correlation of the Lower Ordovician strata

  6. Digestive and appendicular soft-parts, with behavioural implications, in a large Ordovician trilobite from the Fezouata Lagerstätte, Morocco

    Science.gov (United States)

    Gutiérrez-Marco, Juan C.; García-Bellido, Diego C.; Rábano, Isabel; Sá, Artur A.

    2017-01-01

    Trilobites were one of the most successful groups of marine arthropods during the Palaeozoic era, yet their soft-part anatomy is only known from a few exceptionally-preserved specimens found in a handful of localities from the Cambrian to the Devonian. This is because, even if the sclerotized appendages were not destroyed during early taphonomic stages, they are often overprinted by the three-dimensional, mineralised exoskeleton. Inferences about the ventral anatomy and behavioural activities of trilobites can also be derived from the ichnological record, which suggests that most Cruziana and Rusophycus trace fossils were possibly produced by the actions of trilobites. Three specimens of the asaphid trilobite Megistaspis (Ekeraspis) hammondi, have been discovered in the Lower Ordovician Fezouata Konservat-Lagerstätte of southern Morocco, preserving appendages and digestive tract. The digestive structures include a crop with digestive caeca, while the appendages display exopodal setae and slight heteropody (cephalic endopods larger and more spinose than thoracic and pygidial ones). The combination of these digestive structures and the heteropody has never been described together among trilobites, and the latter could assist in the understanding of the production of certain comb-like traces of the Cruziana rugosa group, which are extraordinarily abundant on the shallow marine shelves around Gondwana. PMID:28071705

  7. Hirnantia sagittifera (Brachiopoda and Mucronaspis mucronata s.l. (Trilobita in the Upper Ordovician of the East Baltic: taxonomy and distribution

    Directory of Open Access Journals (Sweden)

    Linda Hints

    2012-05-01

    Full Text Available The brachiopod Hirnantia sagittifera (M’Coy and trilobite morphs of the genus Mucronaspis from the topmost Ordovician Porkuni Stage of the central East Baltic are described and compared with those from the Hirnantian Stage of other regions. These important Hirnantian taxa occur in the Livonian Tongue of the Central Baltoscandian Facies Belt of the Baltic Basin, where the Porkuni Stage is represented by the non-graptolitic Kuldiga and Saldus formations. Hirnantia sagittifera appears in the lowermost part of the Porkuni Stage and is rather widely distributed in the basin in spite of its rare finds in each locality. Our study of trilobites of the genus Mucronaspis has enabled us to observe morphological changes in its exoskeleton in time and to identify a succession of five morphotypes (morphs. In some characteristics these morphs are similar to those of different alleged species of the genus Mucronaspis (M. olini, M. danai, M. ganabina, M. mucronata but they cannot be definitely assigned to any of these species due to some variances. However, here for the first time a stratigraphically ordered collection is presented, which deserves attention in revising the taxonomy of highly variable Mucronaspis. The described brachiopods and trilobites occur mainly in the strata correlated with the Normalograptus extraordinarius graptolite Biozone. However, the uppermost finds of both taxa come from strata correlated with the N. persculptus Biozone.

  8. The regional stratotype section and point for the base of the Hirnantian Stage (the uppermost Ordovician at Mirny Creek, Omulev Mountains, Northeast Russia

    Directory of Open Access Journals (Sweden)

    Koren, Tatyana N.

    2008-03-01

    Full Text Available A complete Hirnantian sequence comprising the Normalograptus extraordinarius and N. persculptus biozones is well developed at the Mirny Creek section in the Omulev Mountains. The underlying beds are assigned to the Appendispinograptus supernus Biozone, and in the overlying strata the lower boundary of the Silurian is precisely defined at the base of the Akidograptus ascensus Biozone. Due to the completeness of the sedimentary and palaeontological record, the Mirny Creek section can be considered as a reference section for the Hirnantian Stage. The succession, about 100 m thick, is composed of calcareous siltstones and marls with pebble-shaped limestones, deposited at a high sedimentation rate in shallow shelf settings. The regional stratotype section and point (RSSP for the lower boundary of the Hirnantian is established at the base of member 68, where Normalograptus extraordinarius first appears. This level can be precisely correlated with that at the GSSP section in Yichang and with the sections in Kazakhstan and North America. The position of the Ordovician-Silurian boundary is redefined and placed at the FAD of A. ascensus at the base of member 74.

  9. LATE ONSET ATRIOVENTRICULAR NODAL TACHYCARDIA

    NARCIS (Netherlands)

    PENTINGA, ML; MEEDER, JG; CRIJNS, HJGM; DEMUINCK, ED; WIESFELD, ACP; LIE, KI

    AV nodal tachycardia may present at any age, but onset in late adulthood is considered uncommon. To evaluate whether onset of AV nodal tachycardias at older age is related to organic heart disease (possibly setting the stage for re-entry due to degenerative structural changes) 32 consecutive

  10. Late onset globoid cell leukodystrophy.

    Science.gov (United States)

    Grewal, R P; Petronas, N; Barton, N W

    1991-11-01

    A 29 year old male with onset of globoid cell leukodystrophy at age 14 is described. This is the first case of enzymatically confirmed globoid cell leukodystrophy with onset of symptoms after the age of ten. This patient is unique because of the late onset and slow progression and extends the clinical spectrum of globoid cell leukodystrophy.

  11. Clerical Exile in Late Antiquity

    DEFF Research Database (Denmark)

    Engberg, Jakob

    2016-01-01

    This volume results from the international research project ‘The Migration of Faith: Clerical Exile in Late Antiquity (325‒c.600)’. The project is a collaboration between the Department of History at the University of Sheffield, the Seminar für Kirchengeschichte at the University of Halle, and th...

  12. LATE ONSET ATRIOVENTRICULAR NODAL TACHYCARDIA

    NARCIS (Netherlands)

    PENTINGA, ML; MEEDER, JG; CRIJNS, HJGM; DEMUINCK, ED; WIESFELD, ACP; LIE, KI

    1993-01-01

    AV nodal tachycardia may present at any age, but onset in late adulthood is considered uncommon. To evaluate whether onset of AV nodal tachycardias at older age is related to organic heart disease (possibly setting the stage for re-entry due to degenerative structural changes) 32 consecutive patient

  13. Late onset startle induced tics

    NARCIS (Netherlands)

    Tijssen, MAJ; Brown, P; Morris, HR; Lees, A

    1999-01-01

    Three cases of late onset Gilles de la Tourette's syndrome are presented. The motor ties were mainly induced by an unexpected startling stimulus, but the startle reflex was not exaggerated. The ties developed after physical trauma or a period of undue emotional stress. Reflex ties may occur in

  14. Late onset startle induced tics

    NARCIS (Netherlands)

    Tijssen, MAJ; Brown, P; Morris, HR; Lees, A

    1999-01-01

    Three cases of late onset Gilles de la Tourette's syndrome are presented. The motor ties were mainly induced by an unexpected startling stimulus, but the startle reflex was not exaggerated. The ties developed after physical trauma or a period of undue emotional stress. Reflex ties may occur in Gille

  15. Late detection of cleft palate

    NARCIS (Netherlands)

    Hanny, K H; de Vries, I A C; Haverkamp, S J; Oomen, K P Q; Penris, W M; Eijkemans, M J C; Kon, M; Mink van der Molen, A B; Breugem, C C

    2016-01-01

    Cleft palate only (CPO) is a common congenital malformation, and most patients are diagnosed within the first weeks after birth. Late diagnosis of the cleft palate (CP) could initially result in feeding and growth impairment, and subsequently speech and hearing problems later in life. The purpose of

  16. Extensional Late Paleozoic deformation on the western margin of Pangea, Patlanoaya area, Acatlán Complex, southern Mexico

    Science.gov (United States)

    Ramos-Arias, M. A.; Keppie, J. D.; Ortega-Rivera, A.; Lee, J. W. K.

    2008-02-01

    New mapping in the northern part of the Paleozoic Acatlán Complex (Patlanoaya area) records several ductile shear zones and brittle faults with normal kinematics (previously thought to be thrusts). These movement zones separate a variety of units that pass structurally upwards from: (i) blueschist-eclogitic metamorphic rocks (Piaxtla Suite) and mylonitic megacrystic granites (Columpio del Diablo granite ≡ Ordovician granites elsewhere in the complex); (ii) a gently E-dipping, listric, normal shear zone with top to the east kinematic indicators that formed under upper greenschist to lower amphibolite conditions; (iii) the Middle-Late Ordovician Las Minas quartzite (upper greenschist facies psammites with minor interbedded pelites intruded by mafic dikes and a leucogranite dike from the Columpio del Diablo granite) unconformably overlain by the Otate meta-arenite (lower greenschist facies psammites and pelites): roughly temporal equivalents are the Middle-Late Ordovician Mal Paso and Ojo de Agua units (interbedded metasandstone and slate, and metapelite and mafic minor intrusions, respectively) — some of these units are intruded by the massive, 461 ± 2 Ma, Palo Liso megacrystic granite: decussate, contact metamorphic muscovite yielded a 40Ar/ 39Ar plateau age of 440 ± 4 Ma; (iv) a steeply-moderately, E-dipping normal fault; (v) latest Devonian-Middle Permian sedimentary rocks (Patlanoaya Group: here elevated from formation status). The upward decrease in metamorphic grade is paralleled by a decrease in the number of penetrative fabrics, which varies from (i) three in the Piaxtla Suite, through (ii) two in the Las Minas unit (E-trending sheath folds deformed by NE-trending, subhorizontal folds with top to the southeast asymmetry, both associated with a solution cleavage), (iii) one in the Otate, Mal Paso, and Ojo de Agua units (steeply SE-dipping, NE-SW plunging, open-close folds), to (iv) none in the Patlanoaya Group. 40Ar/ 39Ar analyses of muscovite from the

  17. Late onset clozapine induced agranulocytosis

    Directory of Open Access Journals (Sweden)

    Rajmohan Velayudhan

    2014-01-01

    Full Text Available Agranulocytosis is defined as an absolute neutrophil count less than 100/mm 3 in association with infectious disease. The risk of agranulocytosis is 0.38% of all clozapine treated cases and there is a relatively lesser incidence in Indian population. The risk of clozapine-induced agranulocytosis and neutropenia is highest in the first 6 months and higher in the initial 18 months after the onset of treatment. There have been very few reports of neutropenia and agranulocytosis after this period. There have so far been no reports of late onset clozapine induced agranulocytosis has been reported from India. A case of late onset clozapine induced agranulocytosis with possible mechanism of the same is reported.

  18. Monomelic amyotrophy with late progression.

    Science.gov (United States)

    Rowin, J; Meriggioli, M N; Cochran, E J

    2001-04-01

    Monomelic amyotrophy is a sporadic juvenile-onset disease that presents with gradual onset of weakness and atrophy in the hand muscles unilaterally. Generally, this disease is considered a 'benign' and non-progressive motor neuron disease, which stabilizes within five years of onset. We discuss a case that illustrates that monomelic amyotrophy may rarely exhibit late clinical progression to the lower extremities after a prolonged period of disease stability.

  19. Late colonization of Easter Island.

    Science.gov (United States)

    Hunt, Terry L; Lipo, Carl P

    2006-03-17

    Easter Island (Rapa Nui) provides a model of human-induced environmental degradation. A reliable chronology is central to understanding the cultural, ecological, and demographic processes involved. Radiocarbon dates for the earliest stratigraphic layers at Anakena, Easter Island, and analysis of previous radiocarbon dates imply that the island was colonized late, about 1200 A.D. Substantial ecological impacts and major cultural investments in monumental architecture and statuary thus began soon after initial settlement.

  20. Research on Water-resisting Characteristics of Carbonate Rock on Top of Ordovician System in Longgu Coal Mine%龙固煤矿奥陶系顶部碳酸盐岩隔水特性分析研究

    Institute of Scientific and Technical Information of China (English)

    戎虎仁; 白海波

    2015-01-01

    To counter to the threat of the Ordovician karst aquifer during the mining of 21st coal seam in Longgu Mine, systematic analysis and research were made in this paper on the lithological property, the development degree of fissures, the filling degree, the structural characteristics of pores, the water inflow from boreholes and so on of the carbonate rock on the top of the Ordovician system. Research results showed that:①There is a relative water-resisting layer with the thickness about 60 m on the top of the Ordovician system, which was composed of Badou limestone stratum with developed fissures and high filling rate and Gezhuang dolomite stratum with nondevelopment of partial fissures;②The fissure percentage of the relative water-resisting layer of BADOU stratum and GEZHUANG on the top of Ordovician system is 2% ~9% and 2% ~3% respectively, with less residual fissures in the relative water-resisting layer and abvious pressure eliminating and water blocking effect;③ The diameter of most pores of the carbonate rock on the top of Ordovician system is less than 30μm, with poor connectivity among them, small effective pore-throat ratio and bad seepage capacity under natural condition;④Drain holes are all located in faults or fractured zones, the water flowing channels such as faults and broken rock are the main zones where the relative water-resisting layer is fractured, and they are also the places need to be detected and controlled during the mining of 21 st coal seam;and⑤There is a relative water-resisting layer in 60 m thick on the top of Ordovician system in Longgu Mine, which can provide a certain protection for the safe mining of 21st coal seam.%针对龙固煤矿21煤开采受奥陶系岩溶含水层威胁的问题,系统分析研究了奥陶系顶部碳酸盐岩的岩性、裂隙发育程度、充填程度、孔隙结构、钻孔涌水量等特性。研究结果表明:①矿区奥陶系顶部存在约60 m厚的相对隔水层,由裂隙发育且

  1. An autochthonous Avalonian basement source for the latest Ordovician Brenton Pluton in the Meguma terrane of Nova Scotia: U-Pb-Hf isotopic constraints and paleogeographic implications

    Science.gov (United States)

    Duncan Keppie, J.; Gregory Shellnutt, J.; Dostal, Jaroslav; Fraser Keppie, D.

    2017-06-01

    The Ediacaran-Ordovician Meguma Supergroup was thrust over Avalonia basement prior to the intrusion of post-Acadian, ca. 370 Ma, S-type granitic batholiths. This has led to two main hypotheses regarding the original location of the Meguma terrane, a continental rise prism bordering either NW Africa or Avalonia. On the other hand, the pre-Acadian, ca. 440 Ma Brenton pluton has yielded the following U/Pb LA-ICP-MS zircon data: (1) 448 ± 3 Ma population peak inferred to be the intrusive age and (2) ca. 550 and 700 Ma inherited ages common to both Avalonia and NW Africa. In contrast, Hf isotopic analyses of zircon yielded model ages ranging from 814 to 1127 Ma with most between 940 and 1040 Ma: such ages are typical of Avalonia and not NW Africa. The ages of the inherited zircons found within the Brenton pluton suggest that it was probably derived by partial melting of sub-Meguma, mid-crustal Avalonian rocks, upon which the Meguma Supergroup was deposited. Although Avalonia is commonly included in the peri-Gondwanan terranes off NW Africa or Amazonia, paleomagnetic data, faunal provinciality, and Hf data suggest that, during the Ediacaran-Early Cambrian, it was an island chain lying near the tropics (ca. 20-30 °S) and was possibly a continuation of the Bolshezemel volcanic arc accreted to northern Baltica during the Ediacaran Timanide orogenesis. This is consistent with the similar derital zircon population in the Ediacaran-Cambrian Meguma Supergroup and the Dividal Group in northeastern Baltica.

  2. Simulation of Linear-Flow Behavior Surrounding Large-Discharge Springs in the Great Valley Cambro-Ordovician Aquifer, West Virginia

    Science.gov (United States)

    Early, J. S.; Donovan, J. J.

    2002-05-01

    The Cambro-Ordovician carbonate aquifer in the Great Valley Region of Berkeley and Jefferson counties, West Virginia, is highly productive but threatened by acute water quality degradation as a result of rapid population growth. A regional-scale equivalent porous medium (EPM) model was developed using MODFLOW and MODPATH to simulate flow in the vicinity of high-discharge springs and community wells. The simulation approach was to develop an initial simplistic steady-state EPM solution using uniform K values distributed by surface-exposed geologic formation, consistent with a large calibration dataset; then this calibrated solution would be adjusted to address local issues involving large-scale heterogeneity, inferred in past studies. The initial simulation employed no anisotropy although its sensitivity was evaluated. A large database of springflows, surface-water baseflow, and target wells was available for calibration. The simulations were calibrated using two independent datasets: 1) hydraulic heads in wells, specifying flows at springs, and 2) estimated long-term average spring flows, specifying heads at springs. These calibrations did not agree; the first method produced excessive drawdowns around springs, while the second yielded very high K values and extremely low hydraulic gradients. The constant-flux method for springs was deemed more consistent with field reality but required implementation of high-contrast heterogeneity in the vicinity of springs, but not wells, to eliminate anomalous drawdown. A linear series of high-K zones was added to simulate suspected karst fracture zones and/or conduits; however, the orientation, style, and location of linear-flow zones are unknown. Simulation of variations in position and orientation of high-K karst zones shows that distinctive head patterns and transient discharge behavior may result from size, length, and relative K contrast of such zones.

  3. Assessing Alternative Processes for the Cause of Under-pressures in the Ordovician Sediments at the Eastern Flank of the Michigan Basin

    Science.gov (United States)

    Normani, S. D.; Yin, Y.; Sykes, J. F.

    2014-12-01

    This study examines the occurrence of anomalous hydraulic under-pressures observed within low hydraulic conductivity (low and intermediate level radioactive waste in Ontario, Canada. At a nominal depth of 460 to 820 m below ground surface, hydraulic formation pressures of 300 m below hydrostatic were measured within Ordovician age carbonates and shales. Three hypotheses for under-pressure formation are examined by means of 1-dimensional numerical analyses: 1) glacial ice-sheet loading; 2) sedimentary erosion and exhumation; and 3) the presence of an immiscible gas phase. Calibration of the numerical models to observed conditions was achieved through manipulation of formation hydraulic diffusivity, loading efficiencies, and hydraulic boundary conditions. In all cases, the calibrated numerical models were able to replicate the observed hydraulic pressure profiles. Simulations of glacial ice-sheet advance-retreat required three 120 ka cycles to yield observed head conditions. The exhumation model suggests that the erosion of approximately 1-2 km of overlying rock can lead to the formation of under-pressures only if the scaled hydraulic diffusivities are 3-4 orders of magnitude less than observed. The immiscible gas analysis, using TOUGH2-MP, provides a favourable match between the simulated and the measured under-pressures if the effective permeabilities are reduced by 2-3 orders of magnitude from observed values. Formation scale hydraulic properties must be exceedingly small to allow under-pressure development and preservation and reflects the value of self-analogues in developing an integrated understanding of deep-seated groundwater systems.

  4. Paleomagnetic study of Cambrian Ordovician rocks in the Eastern Precordillera of Argentina: some constraints on the Andean uplift of this block

    Science.gov (United States)

    Rapalini, A. E.; Bordonaro, O.; Berquo, T. S.

    2000-11-01

    A paleomagnetic study on several carbonatic units (limestones to dolomites) of the Argentine Precordillera, spanning the Middle Cambrian to Arenig, is reported. Sampling was done at 23 sites (140 samples) in five localities of the Eastern Precordillera of San Juan province: Zonda (1), Juan Pobre (2) and La Flecha (3) creeks, Loma Redonda (4) and Cerro Pedernal de los Berros (5). Standard AF and thermal demagnetization indicated two different magnetic behaviors. Samples from localities 1 and 2 showed a single, post-tectonic magnetic component attributed to a Recent viscous or chemical remagnetization. Samples from localities 3 to 5 showed two magnetic components: a low unblocking temperature (350°C) magnetization coincident with that found at the previous localities and a high temperature one (up to 500°C). This second component was also found to be post-folding (post-Devonian?) and its in situ mean direction is Dec: 277.1°, Inc: 69.4, α95: 9.3°, N=10. This is not consistent with any expected direction for the study area between Carboniferous and Recent times. It is therefore inferred that the rocks carrying it underwent substantial tectonic rotation since its recording. Comparison with the magnetization carried by similar Early Ordovician limestones in the Central Precordillera and the San Rafael Block, and assigned to a Permian remagnetizing event, suggests that the same process affected the carbonatic rocks in the Eastern Precordillera and, therefore, the age of the component is likely Permian. Restoration of the in situ mean direction to the expected direction for a Permian remagnetization can be obtained by a 40° ccw rotation around an axis plunging 30° to N30°E. This is compatible with uplifting of the Eastern Precordillera as a series of quasi-rigid blocks along a major E dipping N to NE backthrust during the Andean orogeny.

  5. Cambro-Ordovician post-collisional granites of the Ribeira belt, SE-Brazil: A case of terminal magmatism of a hot orogen

    Science.gov (United States)

    Valeriano, Claudio de Morisson; Mendes, Julio Cezar; Tupinambá, Miguel; Bongiolo, Everton; Heilbron, Monica; Junho, Maria do Carmo Bustamante

    2016-07-01

    This work presents an overview of the geology and chemical composition of the Cambrian-Ordovician post-collisional (COPC) granites and associated rocks of Ribeira belt, SE-Brazil. These COPC granites make up some of the most picturesque and highest (>2000 m) rocky peaks and cliffs of Rio de Janeiro state, an accessible case of post-orogenic granitic magmatism associated with the terminal stages of a hot Ediacaran-Cambrian (Brasiliano-Panafrican) orogen. The COPC magmatism intruded tonalitic to granitic orthogneisses of the Rio Negro arc (∼790-600 Ma) and associated paragneisses of the São Fidelis Group. Post-collisional magmatism started ∼10 m.y. after the latest collisional event, the Buzios Orogeny, lasting discontinuously from ∼510 Ma until ∼470 Ma. The 15 largest intrusive bodies in Rio de Janeiro State are referred to in the literature as the Parati/Mangaratiba, Vila Dois Rios, Pedra Branca, Suruí, Silva Jardim, Favela, Andorinha, Teresópolis, Frade, Nova Friburgo, Conselheiro Paulino, São José do Ribeirão, Sana and Itaoca granites. They crop out as rounded/elliptical stocks or gently-dipping sheets, always with sharp contacts with the country rocks, along with pegmatite and aplitic veins and dykes. COPC granites are grey and pink undeformed medium-grained biotite monzogranites with (K-feldspar) porphyritic, mega-crystic, equigranular and serial textures. Magmatic flow foliation is frequently observed. Peripheric xenolith zones are common as well as isolated xenoliths from the country rocks. In a compilation of more than 100 chemical compositions, SiO2 contents display a major mode at 71wt%. The COPC magmatism generated high-K calc-alkaline granites and quartz monzonites with predominantly metaluminous granites. Meso to melanocratic gabbroic and dioritic enclaves also have calc-alkaline affinity and likely represent more resistant mafic xenoliths from the Rio Negro Arc.

  6. Calcite Twinning in the Ordovician Martinsburg Formation, Delaware Water Gap, New Jersey, USA: Implications for Cleavage Formation and Tectonic Shortening in the Appalachian Piedmont Province

    Directory of Open Access Journals (Sweden)

    John P. Craddock

    2016-02-01

    Full Text Available A traverse across the Stone Church syncline in the Ordovician Martinsburg turbidites reveals an axial planar cleavage (N40°E, SE dips in regional thrust-related folds (N40°E, shallow plunges and five phases of sparry calcite. Calcite fillings are bedding-parallel, cleavage-parallel, and one vein set cross-cuts both earlier phases; the youngest calcite filling is a bedding-parallel fault gouge that crosscuts the cleavage and preserves top-down-to-the-southeast normal fault kinematics. Calcite veins unique to disharmonically-folded calcareous siltstones (Maxwell, 1962 were also analyzed. Stable isotopic analysis (O, C of all of the calcite phases indicates a uniform fluid source (δ13C −2.0, δ18O −13.3 VPDB and, potentially, a similar precipitation and mechanical twinning age. The twinning strains (n = 1341; average Δσ = −32 MPa; average ε1 = −2.9% in the calcite suite are consistent with SE-NW thrust shortening, and sub-horizontal shortening perpendicular to evolving axial planar cleavage planes in the Stone Church syncline. Calcareous siltstone layers within the Martinsburg Fm. turbidites share concordant bedding planes and are unique, chemically (XRF, but folded and cleaved differently than the surrounding clay-rich Martinsburg turbidites. Neither sediment type yielded detrital zircons. Electron backscatter X-ray diffraction (EBSD and calcite twinning results in a folded calcareous siltstone layer preserving a layer-normal SE-NW shortening strain and Lattice Preferred Orientation (LPO. Shortening axes for the five-phase calcite suite trends ~N40°W, consistent with tectonic transport associated with crystalline nappe emplacement of the Reading Prong within the Piedmont province.

  7. Bedded jaspers of the Ordovician Løkken ophiolite, Norway: seafloor deposition and diagenetic maturation of hydrothermal plume-derived silica-iron gels

    Science.gov (United States)

    Grenne, Tor; Slack, John F.

    2003-01-01

    Sedimentary beds of jasper (red hematitic chert) in the Ordovician Løkken ophiolite of Norway are closely associated with volcanogenic massive sulphide (VMS) deposits. The jaspers occur in the immediate hangingwall and laterally peripheral to the large Løkken (25–30 Mt) and small Høydal (0.1 Mt) VMS deposits, and are exposed discontinuously for several kilometres along strike. Massive or laminated types predominate; jasper-sulphide debris-flow deposits are also abundant near VMS deposits. The jaspers contain hematite-rich laminae showing soft-sediment deformation structures and microtextural evidence that record the presence of a colloidal precursor and an origin as gels. Early textures include: (1) straight or curved chains of hematitic filaments 3–10 µm in diameter and 20–100 µm long; (2) branching networks of 15–25 µm-thick, tubular structures surrounded by cryptocrystalline hematite and filled with quartz and euhedral hematite; (3) small (up to 10 µm) spherules composed of cryptocrystalline hematite and silica; and (4) up to 50 µm silica spherules with hematitic cores. The small filaments seem to have been deposited in varying proportions in the primary laminae, possibly together with hematitic and siliceous microspheroids. Diagenetic changes are represented by polygonal syneresis cracks, and the presence of cryptocrystalline (originally opaline) silica, chalcedony, quartz, carbonate and cryptocrystalline hematite and/or goethite forming botryoidal masses and spheroids <10 µm to 5 mm in diameter. Coarser euhedral grains of quartz, carbonate, and hematite are integral parts of these textures. Bleached, silica-rich jaspers preserve only small relics of fine-grained hematite-rich domains, and locally contain sparse pockets composed of coarse euhedral hematite±epidote.

  8. EXTINCTION AND LAZARUS OF THE FAUNAS ACROSS LATE ORDOVICIAN AND EARLY SILURIAN%奥陶系/志留系界线之交生物的绝灭与复苏

    Institute of Scientific and Technical Information of China (English)

    王传尚; 汪啸风; 陈孝红

    2001-01-01

    探讨了奥陶系/志留系界线之交三类代表性生物(笔石、腕足和牙形石)的绝灭与复苏事件,认为persculptus笔石带的底界是一条显著的生物演替界面,从而以宜昌王家湾剖面和persculptus带的底界作为厘定后的全球O/S界线层型剖面和点(GSSP)是符合生物演化规律的.

  9. The Petrogenesis of the Late Cretaceous Mamba Pluton from the Eastern Gangdese: Constraints from Mineralogy

    Science.gov (United States)

    Li, X.

    2011-12-01

    Occurred as stock,the late Cretaceous Mamba pluton, located at the southeast part of the Gangdese terrane, was one of the granitoid intrusions in the Mesozoic-Cenozoic Gangdese gaint magmatic belt, which is composed of Southern Gangdese, Gangdese back-arc fault uplift belt, Middle Gangdes, The Shiquanhe-Laguo Tso-Yongzhu-Nam Tso-Jiali Ophiolitic Méange Zone, and northern Gangdese from south to north, bounded by Indus-Yarlung Zangbo suture zone to the south, and Bangong Tso-Nujiang suture zone to the north(Zhu et al., 2008a), and the Mamba Pluton intruded pre-Ordovician Sumdo Group and early formed intrusions(T3, J1, J3), was unconformably overlied by Eocene Pana Formation. The modal mineralogy of selected samples from Mamba Pluton are calculated via Matlab: quartz(25%), plagioclase(40%), K-feldspar(18%), biotite(9%) and hornblende(5%), with subordinate primary epidote(buffers, but very close to NNO buffer, indicationg relatively moderate oxdizing conditions.. Emplacement depths estimated from aluminum-in-hornblende geobarometry indicate that the Mamba Pluton was emplaced at the pressure of c.a.1.33kbar, corresponding to 4.75km in depth.Temperatures of emplacement calculated with the hornblende-plagioclase thermometer range from 645 Celsius to 780 Celsius.Since the Mamba Pluton and contemporary plutons are unconformably overlain by Eocene volcanic rocks, namley Pana Formation regionally, thus the Mamba pluton must have been exposed at(or near) the surface prior to the Eocene, indicating the existence of protoplateau as proposed by Wang et al(2008).

  10. Late evolution of planetary systems

    Energy Technology Data Exchange (ETDEWEB)

    Morbidelli, A [CNRS, Observatoire de la Cote d' Azur, B P 4299, 06304 Nice Cedex 4 (France); Levison, H F [SWRI, 1050 Walnut St, Suite 300 Boulder, CO 80302 (United States)], E-mail: morby@obs-nice.fr, E-mail: hal@boulder.swri.edu

    2008-08-15

    This chapter discusses some of the main effects of the interaction of planets with remnant planetesimal disks, after the disappearance of the gas. It focuses on planet migration and its possible outcomes. In particular, we discuss the possibility that the migration of the planets leads them into an unstable configuration which changes drastically the structure of the system. The late heavy bombardment (LHB) of the terrestrial planets, occurring 650 Myr after planet formation, is a strong indication that this kind of evolution occurred in our solar system. Other stars show evidence of intense comet showers, which may indicate that LHB-analogs are ongoing in those systems at the current time.

  11. [Left pulmonary agenesis diagnosed late].

    Science.gov (United States)

    Deleanu, Oana; Pătraşcu, Natalia; Nebunoiu, Ana-Maria; Vintilă, V; Ulmeanu, Ruxandra; Mihălţan, F D

    2010-01-01

    We present the case of a 51 years old female-patient, with severe dextroscoliosis, having like unique symptom progressive dyspnea. The blood samples reveals polycythemia, the radiological exam shows the opacification of 2/3 of the left thorax, the absence of the lung structure in the other 1/3, the deviation of the mediastinum, and dextroscoliosis; the computed tomography reveals the absence of the left lung artery and the left airways, compensatory hyperinflation of the right lung and dilatation of the trunk and right pulmonary artery; the bronchoscopy does not visualize the carina or the left main bronchus, typical for pulmonary agenesis. Echocardiography confirmed the absence of left pulmonary artery and shows mild pulmonary hypertension (systolic pressure in the pulmonary artery of 33 mmHg) with dilatation of the right cavities, but good cinetics. We face a case of pulmonary agenesis lately diagnosed, with modest functional cardiologic implications, limited therapeutic options and good survival, justified by the late appearance of the pulmonary hypertension of low severity and without worsening in time.

  12. Processing of Baculovirus Late and Very Late mRNAs

    Institute of Scientific and Technical Information of China (English)

    Linda A. Guarino

    2007-01-01

    Baculoviruses encode a DNA-directed RNA polymerase that is evolutionarily divergent from cellular polymerases. This RNA polymerase is a multifunctional complex that has the ability to recognize late promoters, transcribe linked genes, and process transcripts at both the 5' and 3' ends. The LEF-4 subunit of the viral RNA polymerase is the mRNA capping enzyme, with both RNA triphosphatase and guanylyltransferase activities. Conversion to cap 1 structures is mediated by the viral enzyme MTase1 and another as yet unidentified methyltransferase. Termination is an intrinsic property of the viral RNA polymerase and occurs at oligoU rich sequences. Polyadenylation of the released transcripts is also a function of the viral RNA polymerase. Thus, although viral mRNAs resemble host messages with respect to their 5' and 3' end structures, the processing is mediated by viral enzymes and, in the case of the 3' ends, by mechanisms that differ from the host cell.

  13. Late Mesozoic-Cenozoic décollement structure and its deep geological background in western Shandong,China

    Institute of Scientific and Technical Information of China (English)

    Li Li; Dalai Zhaong; Xiupeng Shi; Zibo Tang; Qiuyuan Hu; Yi Xu; Zhiwei Li

    2009-01-01

    Data from seismic reflection profiles,drilling,stratigraphy,structural deformation studies and physical rock properties reveal the existence of drcollement structures in both shallow and deep levels in western Shandong,China.The most outstanding shallow décollement structures occur along the regional unconformity surface between the Cambrian and Archean,and the disconformity surface between the Carboniferous and Ordovician.The drcollement structure surface manifests as a fault zone with cataclastic rocks and asymmetrical folds.Some of the cataclastic rocks underwent dynamic metamorphism and hydrothermal alteration,including silicification,marbleization and specularite mineralization.Above the decollement structure,the bottom of the Cambrian might be missing or overprinted because of decollement.The striations,asymmetrical folds and boudinage structures indicate the direction of the main décollement tothe NNW and NNE.A deep level decollement structure occurs at a depth of 12-22 km and up to 30 km distance to the south.The early Cretaceous and Eocene are two main periods of activity,with the Cretaceous decollement probably initiated by mantle upwelling derived from subduction and collision of the Yangtze Plate with the North China Plate along the Tancheng-Lujiang Fault in the late Triassicearly Jurassic.This circumstance implies a multidirection of subduction and collision of these two plates in the early late Mesozoic.(C) 2009 National Natural Science Foundation of China and Chinese Academy of Sciences.Published by Elsevier Limited and Science in China Press.All rights reserved.

  14. Late veneer and late accretion to the terrestrial planets

    Science.gov (United States)

    Brasser, R.; Mojzsis, S. J.; Werner, S. C.; Matsumura, S.; Ida, S.

    2016-12-01

    It is generally accepted that silicate-metal ('rocky') planet formation relies on coagulation from a mixture of sub-Mars sized planetary embryos and (smaller) planetesimals that dynamically emerge from the evolving circum-solar disc in the first few million years of our Solar System. Once the planets have, for the most part, assembled after a giant impact phase, they continue to be bombarded by a multitude of planetesimals left over from accretion. Here we place limits on the mass and evolution of these planetesimals based on constraints from the highly siderophile element (HSE) budget of the Moon. Outcomes from a combination of N-body and Monte Carlo simulations of planet formation lead us to four key conclusions about the nature of this early epoch. First, matching the terrestrial to lunar HSE ratio requires either that the late veneer on Earth consisted of a single lunar-size impactor striking the Earth before 4.45 Ga, or that it originated from the impact that created the Moon. An added complication is that analysis of lunar samples indicates the Moon does not preserve convincing evidence for a late veneer like Earth. Second, the expected chondritic veneer component on Mars is 0.06 weight percent. Third, the flux of terrestrial impactors must have been low (≲10-6 M⊕ Myr-1) to avoid wholesale melting of Earth's crust after 4.4 Ga, and to simultaneously match the number of observed lunar basins. This conclusion leads to an Hadean eon which is more clement than assumed previously. Last, after the terrestrial planets had fully formed, the mass in remnant planetesimals was ∼10-3 M⊕, lower by at least an order of magnitude than most previous models suggest. Our dynamically and geochemically self-consistent scenario requires that future N-body simulations of rocky planet formation either directly incorporate collisional grinding or rely on pebble accretion.

  15. Magnetic properties of the remagnetized Middle-Ordovician limestones of the Ponón Trehué Formation (San Rafael Block, central-western Argentina): Insights into the Permian widespread Sanrafaelic overprint

    Science.gov (United States)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.

    2016-10-01

    The widespread Sanrafaelic remagnetization reset most of the early Cambrian to mid-Ordovician carbonate platform of the Argentine Precordillera and the calcareous units of the San Rafael Block. We conducted a detailed rock-magnetic study on the Middle-Ordovician limestones of the Ponón Trehué Formation at both limbs of a tight anticline exposed in the San Rafael Block (Mendoza province, central-western Argentina) that are carriers of a syntectonic magnetization of Permian age. We found that the magnetic overprint in the Ponón Trehué Formation is carried by both pyrrhotite and magnetite, with goethite and subordinate haematite likely related to weathering. Hysteresis parameters, frequency dependence of magnetic susceptibility, Cisowski and modified Lowrie-Fuller tests suggest the presence of ultrafine particles of chemical origin. Demagnetization of natural remanent magnetization and of three-axis isothermal remanence confirm pyrrhotite and magnetite as important contributors to the remanence. Both minerals carry the same magnetic syntectonic component suggesting a coeval or nearly coeval remanence acquisition and therefore mineral formation. This and the results of the magnetic fabric analyses indicate an authigenic origin of the magnetic minerals during folding associated with the Sanrafaelic tectonic phase (ca. 280 Ma). Although the chemically active (oxidizing?) fluids expelled from the orogen as it developed in the early Permian is a viable explanation for the Sanrafaelic remagnetization, the role of the nearly coeval magmatism in Precordillera and the San Rafael Block remains to be properly evaluated.

  16. Study on Rights and Interests Scope Protection of Ordovician Geothermal Single Well in Heze City%菏泽地区奥陶系地热单井开采权益保护范围的研究

    Institute of Scientific and Technical Information of China (English)

    马龙; 冯超臣

    2015-01-01

    菏泽地区地处鲁西南黄泛平原,中低温地热资源丰富,具有良好的开发应用前景。目前菏泽地热的开发利用正处于起步阶段,地热资源的开发利用主要以奥陶纪热储层地热水为主。该文对奥陶系地热单井产能测试和开采权益保护范围进行了描述,对区内地热资源开发利用和地热资源规范管理起到一定的指导作用。%Heze area locates in the yellow flood plain in southwest of Shandong province. Low temperature geother-mal resource is very rich and has very good development prospect. At present, geothermal exploitation and utiliza-tion is in starting stage. Development and utilization of geothermal resources are mainly composed of Ordovician heat reservoir geothermal water. In this paper, single well deliverability test of Ordovician geothermal and protection scope of mining rights have been described. It will guide the development and utilization and formal management of geothermal resources.

  17. 鄂尔多斯盆地西缘奥陶纪生物礁及其储集性能%Ordovician organic reefs and their reservoir property on the west margin of Ordos Basin, China

    Institute of Scientific and Technical Information of China (English)

    周俊烈; 陈洪德; 赵俊兴; 苏中堂; 张成弓; 王玉萍; 郝哲敏

    2013-01-01

    Based on the sedimentary and petroleum geology theory and through the observation of outcrops, cores, and slices and testing analysis, the authors study the Ordovician organic reefs on the west margin of Ordos Basin. The authors reach out a conclusion that the Ordovician organic reefs on the west margin of Ordos Basin are the coral reefs of the Lower Ordovician Zhuozishan Formation located in Wuhai Zhuozishan in the north, the stromatoporoids-sponge reefs of the Lower Ordovician Kelimoli Formation of Well Qitan 1 in the middle and the coral reefs of the Upper Ordovician Beiguoshan Formation in Shijiezigou in the south. The reefs in the north develop earlier than that in the south. The north reefs have grown 2 — 3 phases and that in the south 4 phases. The aquatic environment of the reefs in the north is relatively shallow and the reefs in the south has a deep aquatic environment. The coexistence of different shoals and the reefs develops the reef-bank reservoirs. The reservoir spaces are mainly the organic lattice poles and dissolved poles dissolved by fabrics selectively. The physical conditions show the reservoir property is poor. But, the reefs located on the platform margin are beneficial to developing the reef-bank reservoirs, so the platform margin can be the exploration target.%应用沉积学和石油地质学理论,通过野外剖面观测、岩心观察、室内薄片和测试分析,对鄂尔多斯盆地西缘奥陶纪生物礁进行了详细研究,认为有北部的乌海桌子山地区下奥陶统桌子山组珊瑚生物礁,中部的棋探1井下奥陶统克里摩里组层孔虫—海绵生物礁和南部的石节子沟上臭陶统背锅山组珊瑚生物礁.北部生物礁发育的时代早,南部晚;北段礁体生长发育2~3期,南段发育可达4期;北段及南段生物礁生长的水体环境相对较浅,中部相对较深.生物礁与各种滩共生,发育礁滩型储层,生物格架孔和组构选择性溶蚀的溶孔是其主要储集

  18. Antibiotics in late clinical development.

    Science.gov (United States)

    Fernandes, Prabhavathi; Martens, Evan

    2017-06-01

    Most pharmaceutical companies have stopped or have severely limited investments to discover and develop new antibiotics to treat the increasing prevalence of infections caused by multi-drug resistant bacteria, because the return on investment has been mostly negative for antibiotics that received marketing approved in the last few decades. In contrast, a few small companies have taken on this challenge and are developing new antibiotics. This review describes those antibiotics in late-stage clinical development. Most of them belong to existing antibiotic classes and a few with a narrow spectrum of activity are novel compounds directed against novel targets. The reasons for some of the past failures to find new molecules and a path forward to help attract investments to fund discovery of new antibiotics are described. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Late hemorrhagic disease of newborn.

    Science.gov (United States)

    D'Souza, I E; Rao, S D Subba

    2003-03-01

    The clinical features of 14 infants diagnosed with late hemorrhagic disease of newborn (LHDN), of which 10 did not receive vitamin K prophylaxis, are presented. All infants were exclusively breast-fed and 12 did not have any underlying illness to explain the abnormal coagulation profile. The common presenting symptoms were seizures (71%), vomiting (57%), poor feeding (50%) and altered sensorium (36%). Physical examination shared pallor in all infants and a bulging anterior fontanel in 64%. Intracranial bleed was the predominant manifestation (93%), with CT scan showing intracranial bleed in 78%. Eight infants (57%) succumbed to their illness, while 36%had neurological sequelae. Since LHDN leads to significant morbidity and mortality, it should be prevented by providing vitamin K prophylaxis to all newborns.

  20. Streptococcosis in seabass (Lates calcarifer

    Directory of Open Access Journals (Sweden)

    Wanman, C.

    2005-02-01

    Full Text Available Streptococcus sp. isolated from infected seabass (Lates calcarifer can grow on medium at pH 9.6 and salinity 0 ppt. The lethal dose where the mortality is 50 percent (LD50 was 1.937×103 CFU/ml after 14 days. Diseased fish showed dark body coloration, erratic swimming, exophthalmia, dropsy, pale liver, splenomegaly and hemorrhage in the brain. Blood parameters i.e. haematocrit, haemoglobin, plasma protein and red blood cell of infected fish were decreased, while white blood cells were increased. Histopathological changes in diseased seabass were necrosis, vacuolization and granuloma of the liver, increased number of melanomacrophage in liver and spleen, shrinkage of glomerulus in kidneys, inflammation and necrosis of the spleen and heart, hyperplasia and telangiectasis of the gill, while vacuolization and capsulation of the exophthalmic eyes were observed.

  1. Late onset hereditary episodic ataxia.

    Science.gov (United States)

    Damak, M; Riant, F; Boukobza, M; Tournier-Lasserve, E; Bousser, M-G; Vahedi, K

    2009-05-01

    Episodic ataxias (EA) are hereditary paroxysmal neurological diseases with considerable clinical and genetic heterogeneity. So far seven loci have been reported and four different genes have been identified. Analysis of additional sporadic or familial cases is needed to better delineate the clinical and genetic spectrum of EA. A two generation French family with late onset episodic ataxia was examined. All consenting family members had a brain MRI with volumetric analysis of the cerebellum. Haplotype analysis was performed for the EA2 locus (19p13), the EA5 locus (2q22), the EA6 locus (5p13) and the EA7 locus (19q13). Mutation screening was performed for all exons of CACNA1A (EA2), EAAT1 (EA6) and the coding sequence of KCNA1 (EA1). Four family members had episodic ataxia with onset between 48 and 56 years of age but with heterogeneity in the severity and duration of symptoms. The two most severely affected had daily attacks of EA with a slowly progressive and disabling permanent cerebellar ataxia and a poor response to acetazolamide. Brain MRI showed in three affected members a decrease in the ratio of cerebellar volume:total intracranial volume, indicating cerebellar atrophy. No deleterious mutation was found in CACNA1A, SCA6, EAAT1 or KCNA1. In addition, the EA5 locus was excluded. A new phenotype of episodic ataxia has been described, characterised clinically by a late onset and progressive permanent cerebellar signs, and genetically by exclusion of the genes so far identified in EA.

  2. Late veneer and late accretion to the terrestrial planets

    CERN Document Server

    Brasser, R; Werner, S C; Matsumura, S; Ida, S

    2016-01-01

    It is generally accepted that silicate-metal (`rocky') planet formation relies on coagulation from a mixture of sub-Mars sized planetary embryos and (smaller) planetesimals that dynamically emerge from the evolving circum-solar disc in the first few million years of our Solar System. Once the planets have, for the most part, assembled after a giant impact phase, they continue to be bombarded by a multitude of planetesimals left over from accretion. Here we place limits on the mass and evolution of these planetesimals based on constraints from the highly siderophile element (HSE) budget of the Moon. Outcomes from a combination of N-body and Monte Carlo simulations of planet formation lead us to four key conclusions about the nature of this early epoch. First, matching the terrestrial to lunar HSE ratio requires either that the late veneer on Earth consisted of a single lunar-size impactor striking the Earth before 4.45 Ga, or that it originated from the impact that created the Moon. An added complication is th...

  3. Causes for Late onset Alcohol Use Disorder

    DEFF Research Database (Denmark)

    Emiliussen, Jakob; Nielsen, Anette Søgaard; Andersen, Kjeld

    the available literature on the subject. Method A PRISMA style review and search was performed in late May 2014 and covered MEDLINE, EMBASE, PubMed, and PsychInfo. Inclusion was based on if the study had causes for late-onset AUD in their results section. This revealed 24 articles relevant for this study. After...... not increase the risk for late-onset AUD. However, the data was insufficient to give a reliable quantification of these associations. Discussion A common problem for the studies included (and the ones excluded as well) was the lack of common definitions of late-onset, “stress” and “traumatic life events...

  4. Severe Anaemia during Late Pregnancy

    Directory of Open Access Journals (Sweden)

    Mahenaz Akhtar

    2012-01-01

    Full Text Available Vitamin B12 deficiency is uncommon in pregnancy, it occurs in 10–28% of uncomplicated pregnancies, and is associated with a few complications. We present a case report of a 21-year-old patient with severe anaemia during late pregnancy caused by vitamin B12 deficiency. At 38 weeks gestation and with a BMI of 48.9, a history of rupture of membranes was given but not confirmed. On examination, she appeared pale and therefore full blood counts were done. Interestingly her haemoglobin (Hb levels were 3.7 g/dL. Folate and vitamin B12 levels were also found to be low, and the diagnosis of anaemia caused by vitamin B12 deficiency was made. After treatment with vitamin B12 injections, folic acid and blood transfusions, the patient’s haemoglobin levels improved from 3.7 g/dL to 10.7 g/dL. The conclusion is that effective history taking, diagnosis, and management can prevent many complications that are usually associated with vitamin B12 deficiency anaemia.

  5. Late complications of radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Masaki, Norie [Osaka Prefectural Center for Adult Diseases (Japan)

    1998-03-01

    There are cases in which, although all traces of acute radiation complications seem to have disappeared, late complications may appear months or years to become apparent. Trauma, infection or chemotherapy may sometimes recall radiation damage and irreversible change. There were two cases of breast cancer that received an estimated skin dose in the 6000 cGy range followed by extirpation of the residual tumor. The one (12 y.o.) developed atrophy of the breast and severe teleangiectasis 18 years later radiotherapy. The other one (42 y.o.) developed severe skin necrosis twenty years later radiotherapy after administration of chemotherapy and received skin graft. A case (52 y.o.) of adenoidcystic carcinoma of the trachea received radiation therapy. The field included the thoracic spinal cord which received 6800 cGy. Two years and 8 months after radiation therapy she developed complete paraplegia and died 5 years later. A truly successful therapeutic outcome requires that the patient be alive, cured and free of significant treatment-related morbidity. As such, it is important to assess quality of life in long-term survivors of cancer treatment. (author)

  6. Late Registration: May It Rest in Peace

    Science.gov (United States)

    O'Banion, Terry

    2012-01-01

    Almost every institution of higher education engages in late registration. But evidence is mounting that the practice, originally intended to keep the doors of opportunity open for students as long as possible, wreaks havoc on the ability of colleges to achieve the goals of the emerging completion agenda. Despite best intentions, late registration…

  7. Late Registration: May It Rest in Peace

    Science.gov (United States)

    O'Banion, Terry

    2012-01-01

    Almost every institution of higher education engages in late registration. But evidence is mounting that the practice, originally intended to keep the doors of opportunity open for students as long as possible, wreaks havoc on the ability of colleges to achieve the goals of the emerging completion agenda. Despite best intentions, late registration…

  8. Childhood abuse in late-life depression

    NARCIS (Netherlands)

    Comijs, Hannie C; van Exel, Eric; van der Mast, Roos C; Paauw, Anna; Oude Voshaar, Richard; Stek, Max L

    2013-01-01

    Background: Little is known about the role of childhood abuse in late-life depression. The aim of the study is therefore to study whether childhood abuse is associated with late-life depression according to its onset, and which clinical characteristics play a role in this association. Methods: Data

  9. Childhood abuse in late-life depression

    NARCIS (Netherlands)

    Comijs, H.C.; Exel, E. van; Mast, R.C. van der; Paauw, A.; Oude Voshaar, R.C.; Stek, M.L.

    2013-01-01

    BACKGROUND: Little is known about the role of childhood abuse in late-life depression. The aim of the study is therefore to study whether childhood abuse is associated with late-life depression according to its onset, and which clinical characteristics play a role in this association. METHODS: Data

  10. 16 CFR 444.4 - Late charges.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Late charges. 444.4 Section 444.4 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES CREDIT PRACTICES § 444.4 Late charges. (a) In connection with collecting a debt arising out of an extension of credit to a consumer in or...

  11. Childhood abuse in late-life depression

    NARCIS (Netherlands)

    Comijs, Hannie C; van Exel, Eric; van der Mast, Roos C; Paauw, Anna; Oude Voshaar, Richard; Stek, Max L

    Background: Little is known about the role of childhood abuse in late-life depression. The aim of the study is therefore to study whether childhood abuse is associated with late-life depression according to its onset, and which clinical characteristics play a role in this association. Methods: Data

  12. 7 CFR 925.141 - Late payments.

    Science.gov (United States)

    2010-01-01

    ... payment charge of 5 percent on the unpaid balance on any handler whose assessment has not been received in... rate of 11/2 percent per month shall be applied to the unpaid balance and late payment charge for the... 7 Agriculture 8 2010-01-01 2010-01-01 false Late payments. 925.141 Section 925.141...

  13. Cycads: Fossil evidence of late paleozoic origin

    Science.gov (United States)

    Mamay, S.H.

    1969-01-01

    Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered.

  14. Are we ready to predict late effects?

    DEFF Research Database (Denmark)

    Salz, Talya; Baxi, Shrujal S; Raghunathan, Nirupa;

    2015-01-01

    BACKGROUND: After completing treatment for cancer, survivors may experience late effects: consequences of treatment that persist or arise after a latent period. PURPOSE: To identify and describe all models that predict the risk of late effects and could be used in clinical practice. DATA SOURCES:...

  15. Control of rugose spiraling whitefly using biological insecticides, 2014

    Science.gov (United States)

    The objective of this study was to evaluate the efficacy of selected biological insecticides against a new invasive whitefly pest, Aleurodicus rugioperculatus Martin, in white bird of paradise under field condition. The trial was conducted at United States Horticultural Research Laboratory in Fort P...

  16. Late Abortion: A Comprehensive Review

    Directory of Open Access Journals (Sweden)

    Sheng Chiang

    2005-12-01

    Full Text Available Late termination of pregnancy (LTOP is defined as an abortion carried out beyond 24 gestational weeks, when the fetus has arguably attained viability. In Taiwan, the current abortion law, bearing a eugenic title, allows LTOP on certain medical grounds. However, the fetal and maternal conditions that constitute medical grounds are not clarified and remain legally untested. Professional debate on the abortion issue is also lacking in academia in Taiwan, despite societal concerns. With the advent of technology to detect fetal abnormalities, obstetricians are now confronted more frequently with acute dilemmas regarding LTOP. Quite often, they sail in an uncharted sea with no clinical guidelines from their professional societies or affiliated hospitals. Recently, LTOP at 35 gestational weeks for a fetus with Down syndrome, complicated with polyhydramnios and tetralogy of Fallot, triggered media scrutiny and aroused much public attention. Although the clinical decision making for pregnancies with fetal abnormalities entails increasingly balanced information and consideration in terms of the medical, ethical, legal, psychologic, and societal aspects, society at large is unaware of the complexity and intertwined nature of various abortion issues, especially LTOP. Obstetricians are now in a vulnerable position in Taiwanese society, where litigations relevant to the practice of early abortions are not rare. Therefore, a global and in-depth look into abortion issues from legal and ethical dimensions is indispensable for modern obstetric practice. This review considers the core issues in LTOP, including what conditions constitute a “serious” fetal abnormality to justify LTOP, the incidence of LTOP, legislation regarding LTOP in Western countries, and recent research on ambivalent fetal pain. It will also present procedures, some under the auspices of the ethical committee of a Presbyterian hospital in Taiwan, for clinical decision making, particularly

  17. Magnetic fabric and microstructures of Late Paleozoic granitoids from the North Patagonian Massif: Evidence of a collision between Patagonia and Gondwana?

    Science.gov (United States)

    López de Luchi, Mónica G.; Rapalini, Augusto E.; Tomezzoli, Renata N.

    2010-10-01

    , Cabeza de Vaca Granite and possibly Tardugno Granodiorite were intruded during a major compressional event associated with top-to-the-SSW thrusting. This event is most likely related to a frontal collision of the North Patagonian Massif and the southwestern Gondwana margin at around 300 Ma. The Navarrete Plutonic Complex and San Martin pluton were emplaced after that tectonic event, which must have ended by 281 Ma. Previous magmatic, geochronological and paleomagnetic data that suggest close connection of the North Patagonian Massif with the South American Gondwana blocks during the Paleozoic, can be reconciled with a Late Paleozoic collision by a model of a para-autochthonous North Patagonian Massif that rifted away from Gondwana after the Ordovician and collided again in the Late Carboniferous-Early Permian.

  18. Cholesterol and late-life cognitive decline.

    Science.gov (United States)

    van Vliet, Peter

    2012-01-01

    High cholesterol levels are a major risk factor for cardiovascular disease, but their role in dementia and cognitive decline is less clear. This review highlights current knowledge on the role of cholesterol in late-life cognitive function, cognitive decline, and dementia. When measured in midlife, high cholesterol levels associate with an increased risk of late-life dementia and cognitive decline. However, when measured in late-life, high cholesterol levels show no association with cognitive function, or even show an inverse relation. Although statin treatment has been shown to associate with a lower risk of dementia and cognitive decline in observational studies, randomized controlled trials show no beneficial effect of statin treatment on late-life cognitive function. Lowering cholesterol levels may impair brain function, since cholesterol is essential for synapse formation and maturation and plays an important role in the regulation of signal transduction through its function as a component of the cell membrane. However, membrane cholesterol also plays a role in the formation and aggregation of amyloid-β. Factors that influence cholesterol metabolism, such as dietary intake, are shown to play a role in late-life cognitive function and the risk of dementia. In conclusion, cholesterol associates with late-life cognitive function, but the association is strongly age-dependent. There is no evidence that treatment with statins in late-life has a beneficial effect on cognitive function.

  19. Late-Proterozoic to Paleozoic history of the peri-Gondwana Calabria-Peloritani Terrane inferred from a review of zircon chronology.

    Science.gov (United States)

    Fornelli, Annamaria; Micheletti, Francesca; Piccarreta, Giuseppe

    2016-01-01

    U-Pb analyses of zircon from ten samples of augen gneisses, eight mafic and intermediate metaigneous rocks and six metasediments from some tectonic domains along the Calabria-Peloritani Terrane (Southern Italy) contribute to knowledge of peri-Gondwanan evolution from Late-Proterozoic to Paleozoic times. All samples were equilibrated under amphibolite to granulite facies metamorphism during the Variscan orogeny. The zircon grains of all considered samples preserve a Proterozoic memory suggestive of detrital, metamorphic and igneous origin. The available data fit a frame involving: (1) Neoproterozoic detrital input from cratonic areas of Gondwana; (2) Pan-African/Cadomian assemblage of blocks derived from East and West African Craton; (3) metamorphism and bimodal magmatism between 535 and 579 Ma, within an active margin setting; (4) rifting and opening of Ordovician basins fed by detrital input from the assembled Cadomian blocks. The Paleozoic basins evolved through sedimentation, metamorphism and magmatism during the Variscan orogeny involving Palaeozoic and pre-Paleozoic blocks. The Proterozoic zircon records decidedly decrease in the high grade metamorphic rocks affected by Variscan pervasive partial melting.

  20. An Evaluation of the Carbon Sequestration Potential of the Cambro-Ordovician Strata of the Illinois and Michigan Basins. Part 1. Evaluation of Phase 2 CO2 Injection Testing in the Deep Saline Gunter Sandstone Reservoir (Cambro-Ordovician Knox Group), Marvin Blan No. 1 Hancock County, Kentucky Part 2. Time-lapse Three-Dimensional Vertical Seismic Profile (3D-VSP) of Sequestration Target Interval with Injected Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Bowersox, Richard [Univ. of Illinois, Champaign, IL (United States); Hickman, John [Univ. of Illinois, Champaign, IL (United States); Leetaru, Hannes [Univ. of Illinois, Champaign, IL (United States)

    2012-12-20

    Part 1 of this report focuses on results of the western Kentucky carbon storage test, and provides a basis for evaluating injection and storage of supercritical CO2 in Cambro-Ordovician carbonate reservoirs throughout the U.S. Midcontinent. This test demonstrated that the Cambro- Ordovician Knox Group, including the Beekmantown Dolomite, Gunter Sandstone, and Copper Ridge Dolomite in stratigraphic succession from shallowest to deepest, had reservoir properties suitable for supercritical CO2 storage in a deep saline reservoir hosted in carbonate rocks, and that strata with properties sufficient for long-term confinement of supercritical CO2 were present in the deep subsurface. Injection testing with brine and CO2 was completed in two phases. The first phase, a joint project by the Kentucky Geological Survey and the Western Kentucky Carbon Storage Foundation, drilled the Marvin Blan No. 1 carbon storage research well and tested the entire Knox Group section in the open borehole – including the Beekmantown Dolomite, Gunter Sandstone, and Copper Ridge Dolomite – at 1152–2255 m, below casing cemented at 1116 m. During Phase 1 injection testing, most of the 297 tonnes of supercritical CO2 was displaced into porous and permeable sections of the lowermost Beekmantown below 1463 m and Gunter. The wellbore was then temporarily abandoned with a retrievable bridge plug in casing at 1105 m and two downhole pressure-temperature monitoring gauges below the bridge plug pending subsequent testing. Pressure and temperature data were recorded every minute for slightly more than a year, providing a unique record of subsurface reservoir conditions in the Knox. In contrast, Phase 2 testing, this study, tested a mechanically-isolated dolomitic-sandstone interval in the Gunter.

  1. Experimental late brood surveys: Southern Saskatchewan: 1991

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the late brood surveys for southern Saskatchewan during 1991. Survey methods, weather and habitat conditions, production indices, and tables...

  2. Late onset depression: A recent update

    Directory of Open Access Journals (Sweden)

    Ananya Mahapatra

    2015-01-01

    Full Text Available Late onset depression has recently emerged as a serious mental health issue in the geriatric population with significant public health implications. It is often challenging to diagnose and treat this entity. Various theories have been postulated to elucidate the etiology of late onset depression, but a unifying hypothesis is lacking. Although the vascular hypothesis is most researched; a complex interaction of multiple vulnerability factors is the current focus of attention. Numerous psychosocial variables have been implicated to play a significant role in predicting the onset and severity of late-life depression. Phenomenological differences have been delineated from depression occurring at a younger age, but the findings are equivocal. A better understanding of the natural trajectory of depression in the elderly is required for early diagnosis and effective treatment. This review attempts to summarize the current status of evidence regarding epidemiology, etiology, clinical features, and treatment options available for late-onset depression.

  3. Late Amazonian Glaciations in Utopia Planitia, Mars

    Science.gov (United States)

    Osinski, G. R.; Capitan, R. D.; Kerrigan, M.; Barry, N.; Blain, S.

    2012-03-01

    We present evidence from western Utopia Planitia, including lineated valley fill and lobate debris aprons, for widespread glaciations over a large expanse of the northern plains and dichotomy boundary during Late Amazonian times.

  4. U-Pb Geochronology, Geochemistry and Kinematic Analyses of Subduction-Related Late Triassic Basins in Northern Chile (24.5º-26ºS).

    Science.gov (United States)

    Espinoza, M. E.

    2015-12-01

    In northern Chile (24.5°-26°S) two Pre-Andean depocenters crop out: the Cifuncho basin in the Coastal Cordillera and the Profeta basin in the Precordillera. These basins have been classically interpreted as a continental rifting unrelated to subduction during the period prior to the Andean orogenic cycle. However, recent petrographic and geochemical data suggest the development of these basins in an active subduction system. In order to test this hypothesis and to establish the geologic evolution of the basins and the strain field during the rifting process, we present preliminary U-Pb geochronological and geochemical data together with structural analyses of synrift structures. The geochronological data along the Cifuncho and Profeta basins, show a main continental sedimentary deposition during the Norian to Raethian. Volcanosedimentary rocks show a main detrital supply of Early Permian age (~297-283 Ma). This input can be associated with the volcanic La Tabla Formation and/or the exhumation of Permian granitoids. A minor supply close to ~478 Ma is related to a source from the Lower Ordovician arc (~480 Ma), suggesting the tectonic exhumation of this source to the east of the Profeta basin during the Late Triassic. On the other hand, structural analysis was carried in third and four order extensional faults (<10 m of slip) along the Profeta basin. Most of the faults show a clear synrift character with the development of fault controlled growing strata. The kinematic analyses evidence a variability in the orientation of the maximum strain axes from a main northwest to a subordinate northeast direction of extension. Thus, the intimate relation between the continental sedimentary deposition and a proximal volcanism of intermediate composition and calk-alkaline affinity, suggests the development of these basins in a supra-subduction setting during the Late Triassic. Structural data probably reflect local variation in the strain field across the basins.

  5. LATE TRIASSIC (LATE NORIAN-RHAETIAN RADIOLARIANS FROM THE ANTALYA NAPPES, CENTRAL TAURIDES, SOUTHERN TURKEY

    Directory of Open Access Journals (Sweden)

    UGUR KAGAN TEKIN

    2002-11-01

    Full Text Available The Hocaköy section measured from the Alakirçay Nappe (middle nappe of the Antalya Nappes contain rich radiolarian fauna ranging from late Norian (Late Triassic to middle-late Cenomanian (mid Cretaceous. At the basal part of the section, the Late Triassic (late Norian-Rhaetian Gökdere Formation is characterized by gray to beige cherty limestone at the base and pinkish red chert- gray to beige limestone alternation at the top, with moderately to well-preserved radiolarians in the red chert beds. The overlying Jurassic - Middle Cretaceous Hocaköy Radiolarite is mainly represented by chert-mudstone alternations with some limestone interlayers. Radiolarians of the Gökdere Formation can be well correlated with that of the fauna from the Mino Terrane, central Japan and the fauna from the Queen Charlotte Islands, British Columbia, Canada. Four radiolarian zones from central Japan are recognized in the fauna obtained from Gökdere Formation such as “Praemesosaturnalis multidentatus Lowest Occurrence Zone (TR8A” (late Norian, “Praemesosaturnalis pseudokahleri Lowest Occurrence Zone (TR8B” (late Norian, ? “ Skirt F lowest Occurrence Zone (TR8C” (late Norian-Rhaetian and partly “Haeckelicyrtium breviora Taxon Range Zone (TR8D” (Rhaetian. In comparison with the Queen Charlotte fauna, the two zones “Betraccium deweveri Zone” (late Norian and “Proparvicingula moniliformis Zone” (early Rhaetian are also encountered in the Gökdere Formation. Radiolarians of the uppermost part of the Gökdere Formation indicate that “Globolaxtorum tozeri Zone” defined in Queen Charlotte Islands corresponding to the late Rhaetian, is not present in the section. Five new taxa, Capnuchosphaera okayi, Bistarkum rhaeticum, Praemesosaturnalis heilongjiangensis aksekiensis, P. nobleae, Veghicyclia sanfilippoae were determined within the late Norian-Rhaetian radiolarian fauna of the Gökdere Formation in Hocaköy section.   

  6. Chitinozoan faunas from the Rügen Ordovician (Rügen 5/66 and Binz 1/73 wells), NE Germany.

    Science.gov (United States)

    Samuelsson, J; Verniers, J; Vecoli, M

    2000-12-01

    The island of Rügen (NE Germany), situated close to the Trans-European Suture Zone (TESZ), in the southern Baltic Sea is underlain by sedimentary rocks of an Early Palaeozoic age, known only from boreholes. The wells, Rügen 5/66 and Binz 1/73, were investigated for their chitinozoan assemblages to improve the earlier biostratigraphic dating (graptolites and acritarchs) and to facilitate comparisons with other chitinozoan assemblages on both sides of the TESZ. In the lower part of the Rügen 5/66 core (3794.7-3615.8m), Lagenochitina destombesi Elaouad-Debbaj is indicative of an early late Tremadoc age. In the upper part of the same well (3287.3-1709.7m), the observed chitinozoan taxa suggest an age spanning the early Llanvirn to the Caradoc. The entire sampled interval of the Binz 1/73 core (5217.6-5041.8m) is interpreted as belonging to the Siphonochitina formosa Biozone (early-early late Abereiddian, corresponding to the early Llanvirn). The chitinozoan data corroborate the earlier suggested biostratigraphic ages, based on acritarchs and graptolites. The chitinozoans from the Binz 1/73 well point to a high latitude provenance of the investigated host sediments at time of deposition.

  7. Precursors and Correlates of Anxiety Trajectories from Late Childhood to Late Adolescence

    Science.gov (United States)

    Letcher, Primrose; Sanson, Ann; Smart, Diana; Toumbourou, John W.

    2012-01-01

    The present research employed a prospective, multi-informant design to examine precursors and correlates of differing anxiety profiles from late childhood to late adolescence. The sample consisted of 626 boys and 667 girls who are participants in the Australian Temperament Project, a large, longitudinal, community-based study that has followed…

  8. Late Paleozoic low-angle southward-dipping thrust in the Züünharaa area, Mongolia: tectonic implications for the geological structures in the Sayan-Baikal and Hangai-Daur belts

    Science.gov (United States)

    Onon, Gantumur; Tsukada, Kazuhiro

    2017-02-01

    The Central Asian Orogenic Belt (CAOB) is key to understanding the Paleozoic-Mesozoic geodynamics of Eurasian continent. The geological structure of the Middle-to-Late Paleozoic rock units in the North Mongolia-West Transbaikal region is critical in revealing development process of CAOB. The region is largely comprised of rocks from the continental affinity and accretionary complexes which form the Sayan-Baikal (SB) and Hangai-Daur (HD) belts. This paper describes the lithology, stratigraphy, geological structure, and U-Pb age of the rocks in the Züünharaa area, which is located within the Haraa terrane of the HD belt in Mongolia. We identified a regional low-angle southward-dipping thrust in this area. The tectonic implication of the low-angle south-dipping thrust is discussed within the North Mongolia-West Transbaikal region. The study area exposes metamorphosed clastic rocks of the Haraa Group intruded by Ordovician-Silurian granitic rocks, Devonian felsic volcanic rocks of the Ulaan Öndör Formation, and Visean clastic rocks of the Örmögtei Formation in ascending order. The Haraa Group, granitic rock, and Ulaan Öndör Formation are cut by the low-angle southward-dipping thrust throughout this area. The rocks along the thrust are fractured to form cataclasite zone up to 40 m wide. The thrust includes granite-rhyolite clast of 450-420 Ma, and is unconformably covered by Visean Örmögtei Formation. Therefore, thrusting occurred after Ordovician-Silurian and before Visean. Late Paleozoic low-angle southward-dipping thrusts, similar to the present study, are widely distributed in the Haraa terrane of the Hangai-Daur belt and in terranes of the Sayan-Baikal belt. Whereas, the contemporaneous southeast-verging composite folds and northward-dipping thrusts are developed in the accretionary complexes, which are exposed at south of the Haraa terrane. These contrasting structures suggest a couple of "landward-verging" and "oceanward-verging" structures and may

  9. Diagenetic bitumen in Ordovician carbonate reservoirs of the northern Tarim Basin%塔北地区奥陶系碳酸盐岩中的储层沥青

    Institute of Scientific and Technical Information of China (English)

    张鼐; 王招明; 鞠凤萍; 肖中尧; 房启飞; 张宝收; 卢玉红; 余小庆

    2013-01-01

    According to the relationship between the relative intensity of D-peak, G-peak and G-D peak spacing of bitumens and the maturity of bitumen evolution, we deduced that the Dh/Gh ratio and G-D peak spacing are positively proportional to bitumen maturity. Bitumens in Ordovician reservoir in the northern Tarim Basin are thought to have evolved in three stages and the Dh/Gh ratio and G-D peak spacing of Raman measurements on these bitumens indicated that the first-stage bitumen is highly-mature carbonaceous reservoir bitumen, the second-stage one is mature asphaltene reservoir bitumen, and the third-stage one is a combination of overmature oily reservoir bitumen and asphaltene reservoir bitumen. The formation of the first- and second-stage bitumens is attributed to thermal metamorphism, while the co-existence of two different bitumens for the third-stage bitumen is mainly due to selective adsorption of rocks. The distribution and property of these three-stages bitumens in Ordovician reservoirs of the northern Tarim Basin may determine the nature of Ordovician reservoirs, which is characterized by the southern condensate oil later than the northern heavy oil. The observation of oily reservoir bitumen in the northern Halahatang-Yingmaili region can provide evidence and targets for exploring Himalayan condensate oil reservoirs in this area.%利用沥青质拉曼D峰相对强度、G峰相对强度、两峰间距宽窄与沥青演化成熟度关系,推出Dh/Gh和G-D与沥青成熟度成正比关系图.塔北奥陶系储层中发育3期储层沥青,通过3期储层沥青拉曼Dh/Gh和G-D认为:第Ⅰ期为高热成熟炭质储层沥青,第Ⅱ期为成熟沥青质储层沥青,第Ⅲ期为过成熟油质储层沥青和沥青质储层沥青共存.前两期储层沥青是由于热变质而成,第Ⅲ期两种储层沥青共存主要是岩石选择性吸附导致.3期储层沥青的分布及性质决定塔北奥陶系成藏北部老、南部新,北部重质油、南部凝析油的

  10. 中国新疆塔里木盆地上奥陶统良里塔格组的钙藻化石%CALCAREOUS ALGAE FROM THE UPPER ORDOVICIAN LIANGLITAGE FORMATION IN THE TARIM BASIN; XINJIANG; CHINA

    Institute of Scientific and Technical Information of China (English)

    刘丽静; 杨海军; 潘文庆; 吴亚生

    2012-01-01

    Calcareous algae are the algae which can precipitate carbonate to form carbonate skeletons. Calcareous algae first appear in the Cambrian; and had its first major evolutionary radiation in the Ordovician. The primary calcareous algae are green algae and red algae. This paper discusses the classification criterion of families and genera of the Dasycladales and Udotcaceae of Bryopsidales in Chiorophyta and problems existing in the system classification of Sole-noporaceac in Rhodophyta. The marginal carbonate facies of the Upper Ordovician Lianglitagc Formation include two carbonate platforms in the Tarim Basin; the Central-Bachu larim and Northern Tarim; representing the bank and reef facies with abundant calcareous algae fossils. Thus paper describes 15 species belonging to 11 genera of calcareous algae from the Upper Ordovician Lianglitage Formation of the wells in the Central-Bachu Tarim and Northern Tarim platforms. The Dasyrladales components described herein include Dasyporella;Kazakhstanelia; Vermiporella; Aphroporella;Arthroporella;and the Udoteaceae include Dimor phosiphon and Palaeoporella;; Ajakmalajsoria is regarded as a synonym of Kazakhstanelia; The Solenoporaccae described here include Solenopora; Parachaetetes; and also Petrophyton which is Corallinales incertac familiae. The genus Monilipurella has a uncertain position in the red algae or the green algae.%钙藻是可以发生生物钙化作用形成钙质“骨骼”的分属多个门类的藻类的俗称.钙藻最早出现于寒武纪,奥陶纪发生第一次辐射演化.本文系统讨论了绿藻门绒枝藻目(Dasycladalcs)、羽藻目钙扇藻科(Udoteaceae)的科和属级分类标准和红藻门珊瑚藻科、管孔藻科(Solcnoporaccac)属级分类标准及其中各属分类中存在的问题.塔里木盆地晚奥陶世在塔中—巴楚台地和塔北台地发育了一套礁滩相良里塔格组碳酸盐岩,其中含有丰富的钙藻化石.本文系统描述了来自塔里木盆地塔中

  11. Late effects of thoracic irradiation in children

    Energy Technology Data Exchange (ETDEWEB)

    Boelling, T.; Koenemann, S.; Ernst, I.; Willich, N. [Dept. of Radiotherapy, Univ. Hospital of Muenster (Germany)

    2008-06-15

    Purpose: to summarize the literature regarding the late effects of radiotherapy to the thorax in childhood and adolescence with special emphasis on cardiac and pulmonary impairment. Material und methods: the literature was critically reviewed using the PubMed {sup registered} database with the key words 'late effects', 'late sequelae', 'child', 'childhood', 'adolescence', 'radiation', 'radiotherapy', 'thorax', 'lung', 'heart', and 'pulmonary'. Results: 17 publications dealing with radiation-induced pulmonary and cardiac late sequelae in children could be identified and were analyzed in detail. 29 further publications with additional information were also included in the analysis. Pulmonary function impairment after mediastinal irradiation arose in one third of all pediatric patients, even when treatment was performed with normofractionated lower doses (15-25 Gy). Whole lung irradiation was regularly followed by pulmonary function impairment with differing rates in several reports. However, clinically symptomatic function impairment like dyspnea was less frequent. Irradiation of up to 25 Gy (single doses {<=} 2 Gy) to the heart showed little or no cardiac toxicity in analyses of irradiated children (median follow-up 1.3-14.3 years). Doses of > 25 Gy (single doses {<=} 2-3.3 Gy) led to several cardiac dysfunctions. However, new data from adults with longer follow-up may indicate threshold doses as low as 1 Gy. Impairment of skeletal growth, breast hypoplasia, and secondary malignancy were further potential late sequelae. Conclusion: several retrospective reports described radiation-associated late sequelae in children. However, there is still a lack of sufficient data regarding the characterization of dose-volume effects. (orig.)

  12. Infrared Observations of Late Type Stars

    Science.gov (United States)

    Merrill, K. M.

    1977-01-01

    Substantive mass loss resulting in appreciable circumstellar dust envelopes is common in late-type stars. The evolutionary history and physical state of a cool star determine the chemistry within the outer stellar atmosphere mirrored by the molecular and particulate material present in the envelope. The observational consequences of this debris determined by moderate spectral resolution infrared spectrophotometry are reviewed. Significant information is provided by observations of the emergent energy flux of both the cool stellar photosphere and of the circumstellar dust envelope. The observation suggests that mass-loss occurs to some degree throughout late stellar evolutionary phases and that occasional periods of high mass loss are not uncommon.

  13. Late Cretaceous vicariance in Gondwanan amphibians.

    Directory of Open Access Journals (Sweden)

    Ines Van Bocxlaer

    Full Text Available Overseas dispersals are often invoked when Southern Hemisphere terrestrial and freshwater organism phylogenies do not fit the sequence or timing of Gondwana fragmentation. We used dispersal-vicariance analyses and molecular timetrees to show that two species-rich frog groups, Microhylidae and Natatanura, display congruent patterns of spatial and temporal diversification among Gondwanan plates in the Late Cretaceous, long after the presumed major tectonic break-up events. Because amphibians are notoriously salt-intolerant, these analogies are best explained by simultaneous vicariance, rather than by oceanic dispersal. Hence our results imply Late Cretaceous connections between most adjacent Gondwanan landmasses, an essential concept for biogeographic and palaeomap reconstructions.

  14. Climate predictors of late quaternary extinctions

    DEFF Research Database (Denmark)

    Nogués-Bravo, David; Ohlemüller, Ralf; Batra, Persaram

    2010-01-01

    Between 50,000 and 3,000 years before present (BP) 65% of mammal genera weighing over 44 kg went extinct, together with a lower proportion of small mammals. Why species went extinct in such large numbers is hotly debated. One of the arguments proposes that climate changes underlie Late Quaternary...... extinctions, but global quantitative evidence for this hypothesis is still lacking. We test the potential role of global climate change on the extinction of mammals during the Late Quaternary. Our results suggest that continents with the highest climate footprint values, in other words, with climate changes...

  15. 鄂尔多斯盆地吴起-甘泉地区奥陶系古地貌恢复研究%Study on the Palaeogeomorphology Restoration of Ordovician in Wuqi-Ganquan area of Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    吴海燕; 曹红霞; 于珺; 孙建博; 乔向阳; 强娟; 尚婷; 罗腾跃

    2016-01-01

    依据研究区215口探井的钻井、测井资料,运用沉积地质学、古地理学等方法,对鄂尔多斯盆地古隆起东侧吴起—志丹—甘泉地区的奥陶系马家沟组风化壳岩溶古地貌进行恢复。分别选取本溪组顶8号煤层和马家沟组马五41底部的凝灰岩层为作图基准面,综合利用古地质图法、“印模法”和“残厚法”,并结合铝土岩分布数据,对研究区岩溶古地貌进行恢复。同时,根据研究区不整合面上下地层厚度的组合可以划出上薄+下薄型、上薄+下厚(相对)型、上厚+下薄(相对)型等模型,自西向东将研究区岩溶古地貌划分出2个二级古地貌单元(岩溶高地、岩溶斜坡)和3个三级古地貌单元(潜台、残丘、古沟槽)。%On the basis of drilling and logging data from the 215 wells in the study area, and by means of sedimentary geol-ogy and paleogeography methods, the weathering crust karst paleogeomorphology of Ordovician Majiagou formation in wuqi-zhidan-ganquan area, where is at the eastern side of paleo uplift, has been restored in Ordos Basin. Taken the No. 8 coal seam at the top of Benxi formation and the tuff at bottom of Majiagou five 41 formation as the map reference plane, Compre-hensive utilization of the ancient geological map method impression method and residual thickness method, combined with the data of bauxite that distributed in Ordovician. At the same time, the models can be divided into “up thin plus lower thin”, “up thin plus lower thick”, “up thick plus lower thin” according to the thickness of strata unconformity, hereby the karst palaeogeomorphology also divided into two 2-level units, i. e. karst heights and karst slopes, and three 3-level u-nits, i. e. Hidden units, monadnock and trench, order.

  16. Toetsing van late zwangerschapsafbreking, 2004-2007

    NARCIS (Netherlands)

    Zeeman, G G; Lind, J; Verhagen, Eduard; van de Vathorst, S; Wildschut, H I J; Wolf, H

    2008-01-01

    OBJECTIVE: To provide an inventory of the reported late terminations of pregnancy because ofa severe anomaly of the unborn child, i.e. termination after 24 weeks of pregnancy, in The Netherlands for the period 2004-2007. DESIGN: Inventory and descriptive. METHOD: A description is given of the variou

  17. Shedding further light on late globalization

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    2016-01-01

    In his opening essay on ‘What and/or Who is Late’, Nikhilesh Dholakia delineated inter alia “stage-setting contexts” or levels of analysis which could shed light on the phenomenon of late globalization, including its causes and effects. Indeed, these, especially the effects in contemporary contex...

  18. Tomato late blight (Phytophthora infestans) in Uganda

    NARCIS (Netherlands)

    Tumwine, J.; Frinking, H.D.; Jeger, M.J.

    2002-01-01

    A survey on the tomato late blight situation and current practices for disease management was carried out in Uganda using an informal structured questionnaire approach. Ten districts from different agroclimatic zones were selected for the survey. Phytophthora infestans isolates from tomatoes were ob

  19. Vocabulary of Toddlers Who Are Late Talkers

    Science.gov (United States)

    MacRoy-Higgins, Michelle; Shafer, Valerie L.; Fahey, Katlin J.; Kaden, Elyssa R.

    2016-01-01

    The purpose of this study was to understand vocabulary characteristics in toddlers who are late talkers (LT) as compared with age-matched (AM) and vocabulary-matched (VM) peers. The semantic categories (e.g., animals, foods, toys) and the percentage of nouns, verbs, and closed-class words in the vocabularies of 36 toddlers (12 LT, 12 AM, 12 VM)…

  20. Fast Mapping in Late-Talking Toddlers

    Science.gov (United States)

    Weismer, Susan Ellis; Venker, Courtney E.; Evans, Julia L.; Moyle, Maura Jones

    2013-01-01

    This study investigated fast mapping in late-talking (LT) toddlers and toddlers with normal language (NL) development matched on age, nonverbal cognition, and maternal education. The fast-mapping task included novel object labels and familiar words. The LT group scored significantly lower than the NL group on novel word comprehension and…

  1. Obsessive-Compulsive Disorder in Late Life

    Science.gov (United States)

    Calamari, John E.; Pontarelli, Noelle K.; Armstrong, Kerrie M.; Salstrom, Seoka A.

    2012-01-01

    Although obsessive-compulsive disorder (OCD) has received increasing attention, the study and treatment of OCD in late life has been neglected. The obsessions and compulsions seen with older adults do not appear to differ from the symptoms experienced by other age groups, although developmental issues might influence symptom focus (e.g., memory…

  2. Cannabinoids in late-onset Alzheimer's disease

    NARCIS (Netherlands)

    Ahmed, A.; Marck, M.A. van der; Elsen, G. van den; Olde Rikkert, M.G.M.

    2015-01-01

    Given the lack of effective treatments for late-onset Alzheimer's disease (LOAD) and the substantial burden on patients, families, health care systems, and economies, finding an effective therapy is one of the highest medical priorities. The past few years have seen a growing interest in the medicin

  3. Late Immersion Foundation Document: Teachers and Administrators

    Science.gov (United States)

    Alberta Education, 2010

    2010-01-01

    The aim of this document is to give teachers and administrators the contextual and pedagogical tools for the late immersion program. It acts as a guide for beginning and experienced teachers who need to update their knowledge regarding this program and its details. For many working in this area, it also confirms their daily practices as well as…

  4. Mobile ICT Acceptance in Late Adopter Countries

    DEFF Research Database (Denmark)

    Gimpel, Gregory; Sudzina, Frantisek; Petrovcikova, Katarina

    2014-01-01

    Despite the rapid global diffusion of the smartphone, some countries have experienced much slower uptake of the technology. The low smartphone penetration within Slovakia provides the opportunity to explore what drives smartphone use in late majority countries. Slovakia is a central European nati...

  5. Language Control Abilities of Late Bilinguals

    Science.gov (United States)

    Festman, Julia

    2012-01-01

    Although all bilinguals encounter cross-language interference (CLI), some bilinguals are more susceptible to interference than others. Here, we report on language performance of late bilinguals (Russian/German) on two bilingual tasks (interview, verbal fluency), their language use and switching habits. The only between-group difference was CLI:…

  6. Nephrogenic systemic fibrosis: late skin manifestations

    DEFF Research Database (Denmark)

    Bangsgaard, Nannie; Marckmann, Peter; Rossen, Kristian

    2009-01-01

    BACKGROUND: Nephrogenic systemic fibrosis (NSF) is a serious disease that occurs in patients with severe renal disease and is believed to be caused by gadolinium-containing contrast agents. A detailed description of the late skin manifestations of NSF is important to help dermatologists and nephr......BACKGROUND: Nephrogenic systemic fibrosis (NSF) is a serious disease that occurs in patients with severe renal disease and is believed to be caused by gadolinium-containing contrast agents. A detailed description of the late skin manifestations of NSF is important to help dermatologists...... confluent dermal plaques with thickening and hardening. In contrast, 3 patients presented with wrinkled, redundant skin as seen in cutis laxa. Patients with NSF had significantly poorer scores than control patients on the Daily Life Quality Index (mean [SD], 11. 4 [7.4] vs 1.5 [2. 3]; P ...: This descriptive case series of patients with NSF gives a detailed clinical picture of the skin manifestations late in the disease. It demonstrates that the clinical picture in the late stage has a varied presentation and that NSF has a significant effect on the quality of life....

  7. Late glacial aridity in southern Rocky Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Davis, O.K.; Pitblado, B.L. [Univ. of Arizona, Tucson, AZ (United States)

    1995-09-01

    While the slopes of the present-day Colorado Rocky Mountains are characterized by large stands of subalpine and montane conifers, the Rockies of the late glacial looked dramatically different. Specifically, pollen records suggest that during the late glacial, Artemisia and Gramineae predominated throughout the mountains of Colorado. At some point between 11,000 and 10,000 B.P., however, both Artemisia and grasses underwent a dramatic decline, which can be identified in virtually every pollen diagram produced for Colorado mountain sites, including Como Lake (Sangre de Cristo Mountains), Copley Lake and Splains; Gulch (near Crested Butte), Molas Lake (San Juan Mountains), and Redrock Lake (Boulder County). Moreover, the same pattern seems to hold for pollen spectra derived for areas adjacent to Colorado, including at sites in the Chuska Mountains of New Mexico and in eastern Wyoming. The implications of this consistent finding are compelling. The closest modem analogues to the Artemisia- and Gramineae-dominated late-glacial Colorado Rockies are found in the relatively arid northern Great Basin, which suggests that annual precipitation was much lower in the late-glacial southern Rocky Mountains than it was throughout the Holocene.

  8. Hypothyroidism in late-onset Pompe disease

    Directory of Open Access Journals (Sweden)

    Joseph Schneider

    2016-09-01

    Conclusions: Hypothyroidism was found at a higher prevalence in patients with late-onset Pompe disease compared to the general adult population at UMMC. Studies in larger populations of patients with Pompe disease would be needed to confirm an association of Pompe disease and hypothyroidism. Challenges include finding an adequate sample size, due the rarity of Pompe disease.

  9. Obsessive-Compulsive Disorder in Late Life

    Science.gov (United States)

    Calamari, John E.; Pontarelli, Noelle K.; Armstrong, Kerrie M.; Salstrom, Seoka A.

    2012-01-01

    Although obsessive-compulsive disorder (OCD) has received increasing attention, the study and treatment of OCD in late life has been neglected. The obsessions and compulsions seen with older adults do not appear to differ from the symptoms experienced by other age groups, although developmental issues might influence symptom focus (e.g., memory…

  10. The late maintenance of hippocampal LTP: requirements, phases, 'synaptic tagging', 'late-associativity' and implications.

    Science.gov (United States)

    Reymann, Klaus G; Frey, Julietta U

    2007-01-01

    Our review focuses on the mechanisms which enable the late maintenance of hippocampal long-term potentiation (LTP; >3h), a phenomenon which is thought to underlie prolonged memory. About 20 years ago we showed for the first time that the maintenance of LTP - like memory storage--depends on intact protein synthesis and thus, consists of at least two temporal phases. Here we concentrate on mechanisms required for the induction of the transient early-LTP and of the protein synthesis-dependent late-LTP. Our group has shown that the induction of late-LTP requires the associative activation of heterosynaptic inputs, i.e. the synergistic activation of glutamatergic and modulatory, reinforcing inputs within specific, effective time windows. The induction of late-LTP is characterized by novel, late-associative properties such as 'synaptic tagging' and 'late-associative reinforcement'. Both phenomena require the associative setting of synaptic tags as well as the availability of plasticity-related proteins (PRPs) and they are restricted to functional dendritic compartments, in general. 'Synaptic tagging' guarantees input specificity and thus the specific processing of afferent signals for the establishment of late-LTP. 'Late-associative reinforcement' describes a process where early-LTP by the co-activation of modulatory inputs can be transformed into late-LTP in activated synapses where a tag is set. Recent evidence from behavioral experiments, which studied processes of emotional and cognitive reinforcement of LTP, point to the physiological relevance of the above mechanisms during cellular and system's memory formation.

  11. Reproductive rights: Current issues of late abortion

    Directory of Open Access Journals (Sweden)

    Mujović-Zornić Hajrija

    2009-01-01

    Full Text Available This article considers the legal issues surrounding induced late abortion in cases when severe medical, therapeutic or ethical reasons have not been in dispute. Generally discussing the essential question about abortion today, it means not anymore legality of abortion but, in the first place, safety of abortion. From the aspect of woman health the most important aim is to detect and avoid possible risks of medical intervention, such as late abortion present. This is the matter of medical law context and also the matter of the woman's reproductive rights, here observed through legislation and court practice. The gynecologist has an obligation to obtain the informed consent of each patient. Information's should be presented in reasonably understandable terms and include alternative modes of treatment, objectives, risks, benefits, possible complications, and anticipated results of such treatment. Pregnant woman should receive supportive counseling before and particularly after the procedure. The method chosen for all terminations should ensure that the fetus is born dead. This should be undertaken by an appropriately trained practitioner. Reform in abortion law, making it legally accessible to woman, is not necessarily the product of a belief in woman's rights, but can be a means of bringing the practice of abortion back under better control. Counseling and good medical practice in performing late abortion are the instruments to drive this point even further home. It does not undermine the woman who wants to make a positive decision about her life and its purpose is not to produce feelings of insecurity and guilt. It concludes that existing law should not be changed but that clear rules should be devised and board created to review late term abortion. In Serbia, this leads to creation and set up guidelines for reconciling medical justification for late abortion with existing law, especially with solutions which brings comparative law. .

  12. LATE RENAL GRAFT REJECTION: PATHOLOGY AND PROGNOSIS

    Directory of Open Access Journals (Sweden)

    E.S. Stolyarevich

    2014-01-01

    Full Text Available Rejection has always been one of the most important cause of late renal graft dysfunction. Aim of the study was to analyze the prevalence of different clinico-pathological variants of rejection that cause late graft dysfunction, and evaluate their impact on long-term outcome. Materials and methods. This is a retrospective study that analyzed 294 needle core biopsy specimens from 265 renal transplant recipients with late (48,8 ± 46,1 months after transplantation allograft dysfunction caused by late acute rejection (LAR, n = 193 or chronic rejection (CR, n = 78 or both (n = 23. C4d staining was performed by immunofl uorescence (IF on frozen sections using a standard protocol. Results. Peritubular capillary C4d deposition was identifi ed in 36% samples with acute rejection and in 62% cases of chronic rejection (including 67% cases of transplant glomerulopathy, and 50% – of isolated chronic vasculopathy. 5-year graft survival for LAR vs CR vs their combination was 47, 13 and 25%, respectively. The outcome of C4d– LAR was (p < 0,01 better than of C4d+ acute rejection: at 60 months graft survival for diffuse C4d+ vs C4d− was 33% vs 53%, respectively. In cases of chronic rejection C4d+ vs C4d– it was not statistically signifi cant (34% vs 36%. Conclusion. In long-term allograft biopsy C4d positivity is more haracteristic for chronic rejection than for acute rejection. Only diffuse C4d staining affects the outcome. C4d– positivity is associated with worse allograft survival in cases of late acute rejection, but not in cases of chronic rejection. 

  13. The Aguilar pluton (23°12‧ S-65°40‧ W; NW Argentina): Petrological implications on the origin of the Late Jurassic intraplate magmatism in the Central Andes

    Science.gov (United States)

    Omarini, Ricardo H.; Gioncada, Anna; Vezzoli, Luigina; Mazzuoli, Roberto; Cristiani, Chiara; Sureda, Ricardo J.

    2013-11-01

    The Late Jurassic Aguilar pluton is located in NW Argentina, about 300-400 Km east of the Tarapacá basin, representing the backarc basin linked to the Jurassic volcanic arc. This small-size and compositionally heterogeneous pluton intruded the metasedimentary rocks of the Ordovician Santa Victoria Group, along the Cobres-Salinas Grandes lineament. A revision of published geochemical data in the light of new field and petrological results, allows us to propose a model concerning the petrogenesis and emplacement mechanisms of Aguilar pluton and to discuss its geodynamic setting. The pluton is mainly composed of metaluminous and nearly peraluminous granitoids, showing the geochemical characteristics of ferroan granites. The volumetrically subordinate mafic rocks are both ne- and hy-normative, and their primary magmas were generated by partial melting of a pristine Proterozoic mantle. Aguilar rocks display a rather limited range in (87Sr/86Sr)i, compared to the entire rift-related plutonic suite, i.e., 0.703198-0.704601, and ɛNdt from -1.06 to 3.82, calculated at 149 Ma. Fractional crystallization of mantle-derived magmas and crustal contamination processes explain the evolution to produce strongly silica-oversaturated magmas, which emplaced in the continental crust. The petrological data indicate that magma emplacement and cooling occurred at rather shallow depth. Multiple injections of magma batches into the magma chamber caused mingling and mixing processes early in the crystallization history. The Aguilar pluton is one of the several igneous complexes whose formation was associated with the extensional tectonics active during Late Jurassic-Early Cretaceous in NW Argentina. Based on the geological position and the igneous rocks affinity, we exclude that the Late Jurassic magmatism was generated in an orogenic setting and envisage that it was linked to the early extensional phase that preceded the Cretaceous continental rifting, related to the break-up of the South

  14. U-Pb zircon ages and geochemistry of the Wuguan complex in the Qinling orogen, central China: Implications for the late Paleozoic tectonic evolution between the Sino-Korean and Yangtze cratons

    Science.gov (United States)

    Chen, Longyao; Liu, Xiaochun; Qu, Wei; Hu, Juan

    2014-04-01

    The tectonic evolution of the Qinling orogen, central China, is the key to understanding the assembly of the Sino-Korean and Yangtze cratons. The Wuguan complex, between the early Paleozoic North Qinling and Mesozoic South Qinling tectonic belts, can provide important constraints on the late Paleozoic evolutionary processes in the Qinling orogen. U-Pb zircon analyses, using laser ablation-multicollector-inductively coupled plasma-mass spectrometry, reveal protolith ages of 446 ± 2 Ma for a garnet amphibolite, 368 ± 3 Ma for a meta-andesite, and 351 ± 2 Ma for a mylonitized granitic dike from the Wuguan complex. Elemental geochemistry indicates typical island arc affinities for all the above rocks, but some amphibolites of unknown age have E-MORB signatures. Detrital zircons from a metaquartzite have an age spectrum with a major peak at 462 Ma, two subordinate peaks at 828 and 446 Ma, and a youngest weighted mean age of 423 ± 5 Ma. This suggests that at least some of metasedimentary rocks from the Wuguan complex belong to the part of the Devonian turbidite sequence of the Liuling Group, which was deposited in a fore-arc basin along the southern accreted margin of the Sino-Korean craton, whereas the late Ordovician precursors of the amphibolite might be derived from the Danfeng Group. The occurrence of late Devonian-early Carboniferous arc-related rocks in the Wuguan complex implies penecontemporaneous oceanic subduction, and therefore the Paleo-Qinling Ocean was not finally closed until the early Carboniferous. On the other hand, metamorphic zircon grains from two amphibolites yielded ages of 321 ± 2 and 318 ± 3 Ma. Hence, the Wuguan complex in the Qinling orogen and the Guishan complex in the Tongbai orogen constitute a medium-pressure Carboniferous metamorphic belt that is more than 500 km long, and which was formed in the hanging wall of a subduction zone.

  15. REVISION OF THE ORDOVICIAN WUBINAOBAO FORMATION IN HONGGOR AREA, INNER MONGOLIA%内蒙古红格尔苏木地区奥陶系乌宾敖包组重新厘定

    Institute of Scientific and Technical Information of China (English)

    宝音乌力吉; 贺宏云; 宋华; 鞠文信; 韩宗庆

    2011-01-01

    During the 1:50000 regional geological survey in Honggor area on the north of Erenhot, Inner Mongolia, near the border between China and Mongolia, the Ordovician Wubinaobao formation is redefined on the basis of rock association, paleontological characteristics, depositional environment, etc. The revised Wubinaobao formation includes a set of layers of slate and siltstone with intercalations of thin limestone lenticules, containing fossils of Trilobita, Brachiopoda, etc. The strata are characterized by neritic shelf sedimentation. This redefinition is significant for the ore-prospecting in this area from now on.%2008年在内蒙古二连浩特北红格尔苏木中蒙边境一带开展1∶5万区调时,根据岩石组合、古生物特征、沉积环境等,对建组于该地区的奥陶系乌宾敖包组进行了重新厘定.重新厘定后的乌宾敖包组为原乌宾敖包组中含三叶虫、腕足等化石的一套板岩、粉砂岩夹薄层灰岩透镜体等,具浅海陆棚沉积特征的地层.该地层的重新厘定对本区开展找矿工作有指导意义.

  16. Youth Indicators of Late-M Dwarfs

    Science.gov (United States)

    Feldman, Daniel; Cruz, K.; Lépine, S.; Alpert, N.

    2011-01-01

    We present a study in which we searched for a correlation between weak Na absorption doublet (8183Å, 8194Å) and strong H-Alpha emission (6563Å) in late-M dwarf stars (M6-M9), as both are indicative of youth. Our sample consists of late-M Dwarfs from the LSPM Survey (Lépine and Shara, 2005), which contain stars with measured proper motions of mu > 40 mas/yr. Measurements for emission and absorption strength were made using spectral indices. Our preliminary results are presented; future work will include a similar analysis of early type M Dwarfs, as well as kinematics. This work was funded by the CUNY Summer Undergraduate Research Program, as well as the CUNY Macaulay Honors College, and we acknowledge the hospitality of the American Museum of Natural History.

  17. An emerging antiarrhythmic target: late sodium current.

    Science.gov (United States)

    Banyasz, T; Szentandrássy, N; Magyar, J; Szabo, Z; Nánási, P P; Chen-Izu, Y; Izu, L T

    2015-01-01

    The cardiac late sodium current (INa,L) has been in the focus of research in the recent decade. The first reports on the sustained component of voltage activated sodium current date back to the seventies, but early studies interpreted this tiny current as a product of a few channels that fail to inactivate, having neither physiologic nor pathologic implications. Recently, the cardiac INa,L has emerged as a potentially major arrhythmogenic mechanism in various heart diseases, attracting the attention of clinicians and researchers. Research activity on INa,L has exponentially increased since Ranolazine, an FDA-approved antianginal drug was shown to successfully suppress cardiac arrhythmias by inhibiting INa,L. This review aims to summarize and discuss a series of papers focusing on the cardiac late sodium current and its regulation under physiological and pathological conditions. We will discuss critical evidences implicating INa,L as a potential target for treating myocardial dysfunction and cardiac arrhythmias.

  18. Ribbed vaults of late Gothic in Sardinia

    Directory of Open Access Journals (Sweden)

    Paola Casu

    2012-06-01

    Full Text Available The late Gothic construction practice, settled in the Spanish Mediterranean area, is based on predetermined geometric rules and is shown in religious buildings with ribbed vaults. The proportion between the sides of the area to cover, tracing plan of the ribs as a succession of corner bisectors, stereotomy problems and volumetric aspects, are just some of the elements that can describe the complex construction of a ribbed vault. The aim of this paper is to analyze the dimensional information of the late gothic ribbed vaults of Sardinia, in order to define the geometric and proportional rules for a correct drawing, establishing a standard procedure for the collection of measures and the construction of the 3D model of vaults.

  19. Educating Citizens in Late Modern Societies

    DEFF Research Database (Denmark)

    Christensen, Torben Spanget

    2011-01-01

    . The model is based on the fundamental belief that the overall aim of civic education in democratic, late modern and global societies is empowerment of the citizen in order to establish a self governing citizen who simultaneous is capable of managing and keeping together partly contradictory citizens tasks....... One is being a loyal subject in state and society affairs, a second is being an informed voter in state elections, a third is being a critical participant in state and society affairs and a forth is being an independent, innovative citizen outside state. The model is inspired by rather comprehensive......One way or the other democratic states need to take on the task of educating its rising generation in governmental affairs, societal matters and citizenship in order to sustain the democracy itself. This article presents a model for analysing civic education in late modern, globalised world...

  20. Early- versus Late-Onset Systemic Sclerosis

    Science.gov (United States)

    Alba, Marco A.; Velasco, César; Simeón, Carmen Pilar; Fonollosa, Vicent; Trapiella, Luis; Egurbide, María Victoria; Sáez, Luis; Castillo, María Jesús; Callejas, José Luis; Camps, María Teresa; Tolosa, Carles; Ríos, Juan José; Freire, Mayka; Vargas, José Antonio; Espinosa, Gerard

    2014-01-01

    Abstract Peak age at onset of systemic sclerosis (SSc) is between 20 and 50 years, although SSc is also described in both young and elderly patients. We conducted the present study to determine if age at disease onset modulates the clinical characteristics and outcome of SSc patients. The Spanish Scleroderma Study Group recruited 1037 patients with a mean follow-up of 5.2 ± 6.8 years. Based on the mean ± 1 standard deviation (SD) of age at disease onset (45 ± 15 yr) of the whole series, patients were classified into 3 groups: age ≤30 years (early onset), age between 31 and 59 years (standard onset), and age ≥60 years (late onset). We compared initial and cumulative manifestations, immunologic features, and death rates. The early-onset group included 195 patients; standard-onset group, 651; and late-onset, 191 patients. The early-onset group had a higher prevalence of esophageal involvement (72% in early-onset compared with 67% in standard-onset and 56% in late-onset; p = 0.004), and myositis (11%, 7.2%, and 2.9%, respectively; p = 0.009), but a lower prevalence of centromere antibodies (33%, 46%, and 47%, respectively; p = 0.007). In contrast, late-onset SSc was characterized by a lower prevalence of digital ulcers (54%, 41%, and 34%, respectively; p < 0.001) but higher rates of heart conduction system abnormalities (9%, 13%, and 21%, respectively; p = 0.004). Pulmonary hypertension was found in 25% of elderly patients and in 12% of the youngest patients (p = 0.010). After correction for the population effects of age and sex, standardized mortality ratio was shown to be higher in younger patients. The results of the present study confirm that age at disease onset is associated with differences in clinical presentation and outcome in SSc patients. PMID:24646463

  1. Reengineering Engineering: A Glimpse of Late Professionalism

    OpenAIRE

    Callaham, Arthur A.

    1999-01-01

    The role of the engineer in the late capitalist society of the last half century has been misunderstood at best. The lack of a consistent job description for engineers in various fields, a lack of job security, and a lack of respect from both industry and society have spawned severe angst in the engineering community. A classic remedy for this situation has been the rallying of engineering practitioners under a banner of increased professionalism. If engineers could make themselves more li...

  2. [Late primary abdominal pregnancy. Case report].

    Science.gov (United States)

    Farías, Emigdio Torres; Gómez, Luis Guillermo Torres; Allegre, René Márquez; Higareda, Salvador Hernández

    2008-09-01

    Abdominal advanced pregnancy is an obstetric complication that put at risk maternal and fetal life. We report a case of advanced abdominal pregnancy with intact ovaries and fallopian tubes, without ureteroperitoneal fistulae and, late prenatal diagnosis, in a multiparous patient without risk factors, with alive newborn, and whose pregnancy was attended at Unidad Medica de Alta Especialidad, Hospital de Gineco-Obstetricia, Centro Medico Nacional de Occidente del IMSS, Guadalajara, Jalisco, México.

  3. Late-time cosmological phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N. (Chicago Univ., IL (USA) Fermi National Accelerator Lab., Batavia, IL (USA))

    1990-11-01

    It is shown that the potential galaxy formation and large-scale structure problems of objects existing at high redshifts (Z {approx gt} 5), structures existing on scales of 100M pc as well as velocity flows on such scales, and minimal microwave anisotropies ({Delta}T/T) {approx lt} 10{sup {minus}5} can be solved if the seeds needed to generate structure form in a vacuum phase transition after decoupling. It is argued that the basic physics of such a phase transition is no more exotic than that utilized in the more traditional GUT scale phase transitions, and that, just as in the GUT case, significant random gaussian fluctuations and/or topological defects can form. Scale lengths of {approximately}100M pc for large-scale structure as well as {approximately}1 M pc for galaxy formation occur naturally. Possible support for new physics that might be associated with such a late-time transition comes from the preliminary results of the SAGE solar neutrino experiment, implying neutrino flavor mixing with values similar to those required for a late-time transition. It is also noted that a see-saw model for the neutrino masses might also imply a tau neutrino mass that is an ideal hot dark matter candidate. However, in general either hot or cold dark matter can be consistent with a late-time transition. 47 refs., 2 figs.

  4. Pyomyositis of Obturator Muscles: Unusual Late Presentation

    Directory of Open Access Journals (Sweden)

    Prasad Channappa Soraganvi

    2013-04-01

    Full Text Available Introduction: Pyomyositis of obturator muscles is rare condition. Late presentation with deformities of hip misleads the clinician. Late presentation (6 weeks of this condition has not been reported earlier. This report highlights this unusual presentation of Pyomyositis of the obturator muscles. Case Report: We are reporting a 14year old female patient presented with limp and pain in hip since 6 weeks. Her hip radiographs were unremarkable. Patient was admitted and MRI done. MRI findings were consistent with obturator pyomyositis. Diagnosis of pyomyositis confirmed by MRI and we performed percutaneous aspiration and drained about 25ml of purulent material mixed with blood. The culture grew Staphylococcus aureus. Patient received intravenous antibiotic for 1week and oral antibiotic for 2weeks. Patient was immobilized in fixed skin traction in Thomas splint for 5days, later gentle mobilization was started. Her condition improved dramatically after aspiration. A follow up MRI done at 3 weeks following aspiration revealed a significant reduction in intramuscular collection of obturator internus and obturator externus. Three weeks following aspiration patient was relieved of the pain and was able to walk normally. At 6 months follow up visit patient was asymptomatic. Conclusion: Late presentation of obturator pyomyositis is rare. We emphasise on careful examination and need for early imaging for diagnosis. Percutaneous drainage results in successful treatment. Keywords: Pyomyositis, septic arthritis, infection, obturator muscle.

  5. VERY LATE PHOTOMETRY OF SN 2011fe

    Energy Technology Data Exchange (ETDEWEB)

    Kerzendorf, W. E. [Department of Astronomy and Astrophysics, University of Toronto, 50 Saint George Street, Toronto, ON M5S 3H4 (Canada); Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J., E-mail: wkerzendorf@gmail.com [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, D-85748 Garching (Germany)

    2014-12-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of {sup 56}Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs.

  6. Very late photometry of SN 2011fe

    CERN Document Server

    Kerzendorf, W E; Seitenzahl, I R; Ruiter, A J

    2014-01-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (> 900 d) of thermonuclear supernovae. These late stages allow for a direct measurement of the decay processes of nuclei synthesized in the core of the explosion. In this paper, we present our photometric data of SN 2011fe taken at an unprecedentedly late epoch of ~ 930 d with GMOS-N mounted on the Gemini North telescope (g=23.37+/- 0.25, r=24.03 +/- 0.09, i=23.90 +/- 0.15, and z=23.74 +/- 0.16) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of 56Co. This is in spite of several theoretical predictions that advocate a substantial energy redistribution and/or loss via various processes wh...

  7. Cambro-Ordovician magmatism in the Araçuaí Belt (SE Brazil): Snapshots from a post-collisional event

    Science.gov (United States)

    De Campos, Cristina P.; de Medeiros, Silvia R.; Mendes, Julio C.; Pedrosa-Soares, Antonio C.; Dussin, Ivo; Ludka, Isabel P.; Dantas, Elton L.

    2016-07-01

    The focus of the present work is the rebound of the magmatism at the late stages of orogenic collapse in the Araçuaí Belt, in Brazil. At the end of the orogen bimodal inversely zoned plutons were emplaced along a tectonic corridor following the Atlantic coast of Brazil. This event culminates around 500 Ma. We review geology, petrography, geochemistry and geochronology of these plutonic structures in the region of Espírito Santo. New geochemical modeling of trace element data together with new whole rock Sm-Nd and Rb-Sr isotopic data depict a gradual process of mantle contamination during different stages of the orogen. In the post-orogenic stage contamination reaches extreme values. Basic rocks reach εNd(0.5Ga) values below -10. Gabbros to peridotites are more enriched in Ba, Zr, LREE and Sr than the surrounding metasediments. Four new U-Pb data sets from determinations in zircon and monazite crystals, (central northern part of the belt) confirm peak magma production around 500 ± 15 Ma, ranging up to 525 ± 3 Ma in one of the structures. Based on the pictured data, we discuss the significance of this magmatism and present a possible model: a process of gradational delamination of the subcontinental lithospheric mantle and adjacent deep continental crust through underplating. As a consequence, an already enriched mantle was dramatically further contaminated. At the end of this event the intrusion of alkaline melts, with less negative εNd (-5) and further enrichment in incompatible elements, point towards a new input of deeper juvenile mantle magma. Our data suggest the possible onset of a hotspot due to the destabilization of the asthenospheric mantle after orogenic collapse.

  8. Comparing Measures of Late HIV Diagnosis in Washington State

    Directory of Open Access Journals (Sweden)

    Laura Saganic

    2012-01-01

    Full Text Available As more US HIV surveillance programs routinely use late HIV diagnosis to monitor and characterize HIV testing patterns, there is an increasing need to standardize how late HIV diagnosis is measured. In this study, we compared two measures of late HIV diagnosis, one based on time between HIV and AIDS, the other based on initial CD4+ results. Using data from Washington's HIV/AIDS Reporting System, we used multivariate logistic regression to identify predictors of late HIV diagnosis. We also conducted tests for trend to determine whether the proportion of cases diagnosed late has changed over time. Both measures lead us to similar conclusions about late HIV diagnosis, suggesting that being male, older, foreign-born, or heterosexual increase the likelihood of late HIV diagnosis. Our findings reaffirm the validity of a time-based definition of late HIV diagnosis, while at the same time demonstrating the potential value of a lab-based measure.

  9. Comparing Measures of Late HIV Diagnosis in Washington State

    OpenAIRE

    Laura Saganic; Jason Carr; Rosa Solorio; Maria Courogen; Tom Jaenicke; Ann Duerr

    2011-01-01

    As more US HIV surveillance programs routinely use late HIV diagnosis to monitor and characterize HIV testing patterns, there is an increasing need to standardize how late HIV diagnosis is measured. In this study, we compared two measures of late HIV diagnosis, one based on time between HIV and AIDS, the other based on initial CD4+ results. Using data from Washington's HIV/AIDS Reporting System, we used multivariate logistic regression to identify predictors of late HIV diagnosis. We also con...

  10. Intracranial hemorrhages and late hemorrhagic disease associated cholestatic liver disease

    OpenAIRE

    2012-01-01

    Deficiency of vitamin K predisposes to early, classic or late hemorrhagic disease of the newborn (HDN); of which late HDN may be associated with serious and life-threatening intracranial hemorrhage. Late HDN is characterized intracranial bleeding in infants aged 1 week to 6 months due to severe vitamin K deficiency. Late HDN is still an important cause of mortality and morbidity in developing countries where vitamin K prophylaxis is not routinely practiced. Children with cholestatic liver dis...

  11. Seismic modeling, rock physics, avo and seismic attribute analysis for illuminating sandstone facies of the Late Ordovic Ian Mamuniyat Reservoir, R-Field, Murzuq Basin-Libya

    Science.gov (United States)

    Abushalah, Yousf Milad

    The Late Ordovician Mamuniyat Formation is the main hydrocarbon reservoir in the R-Field in Murzuq Basin, SW Libya. The Lower Mamuniyat, which is the only unit that was encountered in the study area, is composed of sandstone facies called Clean Mamuniyat and shaly sandstone facies called Dirty Mamuniyat. One major problem with the development of the R-Field is the difficulty of distinguishing the two units so this project was aimed to develop better methods for distinguishing between the two units of the Lower Mamuniyat. The other problem is to distinguish the transgressive shaly facies of the Bir Tlacsin, which has an impact on the hydrocarbon accumulation. Those issues manifested in limit of seismic resolution and interference that resulted from the converted shear mode waves. The dissertation was divided into three chapters. In the first chapter, seismic modeling using a deterministic and a Ricker wavelet were used to investigate the interference effects on the poststack seismic data and a bandpass filter was used to remove those effects. Instantaneous frequency, spectral-based colored inversion and rock physics were, then applied to determine the distributions of the sandstone facies of the Lower Mamuniyat Formation and to interpret the depositional setting of it. In the second chapter, spectral decomposition and inverted density were utilized to determine the distribution of the shaly facies of Bir Tlacsin, and its temporal thickness and to remap the top reservoir. In the last chapter, amplitude variation with offset (AVO) modeling, ray tracing, and spectral analysis were used to investigate the mode conversion and its effect on AVO signature, the amplitude of the near-mid and far offsets and frequency contents. Data enhancement then was performed using partial stacks and a bandpass filter.

  12. 7 CFR 981.481 - Interest and late payment charges.

    Science.gov (United States)

    2010-01-01

    ..., within 60 days of the invoice date. The late payment charge shall be 10 percent of the unpaid balance. ... 7 Agriculture 8 2010-01-01 2010-01-01 false Interest and late payment charges. 981.481 Section 981... GROWN IN CALIFORNIA Administrative Rules and Regulations § 981.481 Interest and late payment charges. (a...

  13. 鄂尔多斯盆地苏里格地区奥陶系马家沟组白云石化%Dolomitization of Ordovician Majiagou Formation in Sulige region, Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    付金华; 王宝清; 孙六一; 包洪平; 徐波

    2011-01-01

    The Ordovician Majiagou Formation in Sulige region of the Ordos Basin was deposited in hypersaline restricted epicontinental environment. It is mainly composed of carbonate rocks with thin evaporate interbeds. The dolomites are classified into 3 kinds; micrite, fine-medium crystal dolomite, and dolomite filled in pores and fractures. The Na concentrations range from 0 to 2 099 X 10-6, the Sr concentrations range from 0 to 70 X 10-6,the Mn concentrations range from 0 to 112 X 10-6, and the Fe concentrations range from 39 to 86 746 X 10-6 in dolomites. The dolomites are characterized with varied Na, low Sr and Mn, and high Fe concentrations. The 18O values for dolomites range from -16. 00%0 to -5. 73%o, and the 13C values range from -11. 46%0 to 1. 90%. (PDB). It indicates that carbonate rocks have experienced leaching and burial diagenesis. Most filled dolomites have lower 18O and 13C values than surrounding components, indicating that the former was formed later. The dolomites are characterized with low degrees of order and less stoichiometry. The 87Sr/86 Sr values of dolomites range from 0. 707 977±0. 000 070 to 0. 711 791±0. 000 064, most of which are higher than that corresponding to global boundary between middle and upper Ordovician. Microbial dolomitization is the reason for dolomite genesis.%苏里格地区马家沟组为一套碳酸盐岩为主,夹蒸发岩的地层,沉积于超盐度的局限陆表海环境.白云石分为以泥晶结构为主的,以细—中晶结构为主和充填于孔、缝中3类.白云石Na含量(0~2 099)×10-6,Sr含量(0~70)×10-5,Mn含量(0~112)×10-6,Fe含量(39~86 746)×10-6,以变化较大的Na含量、低的Sr和Mn含量,高的Fe含量为特征.白云石δ18()值在-16.00‰~-5.73‰之间,δ13C值在-11.46‰~1.90‰之间,说明碳酸盐岩经历了淋滤作用和埋藏作用.大多数孔、缝充填白云石较围岩组分有较低的δ18O和δ13C值,说明孔缝充填的白云石形成较晚.白云石以低

  14. Efusiones subácueas del arco volcánico ordovícico en el norte del sistema de Famatina Subaqueous eruptions in the Ordovician volcanic arc in the northern Famatina System

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    Clara Eugenia Cisterna

    2010-03-01

    Full Text Available La sucesión volcánica - sedimentaria analizada, ubicada entre los 27°47`00" - 27°49`18" S y 68°04`52" - 68°02`27" O en la sierra de Las Planchadas, norte del Sistema de Famatina, registra la evolución de un arco volcánico ordovícico. Sus representantes volcánicos mayoritarios, lavas basálticas y en menor medida dacíticas, fragmentadas, autoclásticas e hialoclastitas indican el predominio de un volcanismo efusivo subácueo. Mientras tanto el elevado volumen de depósitos volcaniclásticos asociados, especialmente en los tramos superiores, generados por flujos gravitacionales en masa, ya sea por corrientes de turbidez, como por flujos de detritos y vinculados con episodios de sedimentación sin-volcánicos, evidencian la eficiencia de los procesos de fragmentación y de la erosión recurrente durante la evolución de esta cuenca ordovícica. El contenido fosilífero en las facies volcanogénicas y las asociaciones de limolitas, fangolitas y psamitas finas con abundante material de origen piroclástico y lapilli acrecional, atestiguan en favor de un ambiente somero para su depositación. Las características de los depósitos volcanogénicos, su proveniencia prácticamente única, la variación de sus facies, junto a las características geoquímicas de sus representantes magmáticos apoyan la idea para la región de un volcanismo de arco ligado a la evolución de la cuenca, mientras tenía lugar un intermitente aporte de sedimentos intracuencales, debidos a la inestabilidad de la misma.The volcanic - sedimentary sequence studied, exposed along the 27°47`00" - 27°49`18" S and 68°04`52" - 68°02`27" Win the sierra de Las Planchadas, northern Famatina System, records the evolution of an Ordovician volcanic arc. The main volcanic members are basaltic and dacitic lavas and significant volumes of lava-derived clastic aggregates that are produced by quench fragmentation and gravitational collapse. Fragmented lavas, autobreccias and

  15. Late-presenting congenital diaphragmatic hernia

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    Raashid Hamid

    2014-01-01

    Full Text Available Background: This study was undertaken to highlight the clinical profile, misdiagnosis, surgical treatment,and prognosis of late-presenting congenital diaphragmatic hernia (CDH cases in a tertiary level hospital. Patients and Methods: This retrospective study included all the babies and children >1 month of age with CDH who were admitted in our Hospital (Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Kashmir, India during the period between January 2008 and December 2013. Babies with age <1 month were excluded from the study. Data regarding clinical profile, operative records, and follow-up was reviewed and analysed statistically. Results: A total of 20 patients were included in this study. The clinical picture ranged from respiratory distress (13 patients to non-specific gastrointestinal complaints (5 patients. In two patients, CDH was misdiagnosed as pneumothorax and had got chest tube inserted in other hospitals before referral to this tertiary care centre. In 14 patients chest, X-ray revealed the diagnosis of CDH and in remaining five patients (including the two patients with misdiagnosis further investigations were undertaken to establish the diagnosis. Age ranged from 45 days to 17 years with an average age of 58.9 months. There were 12 male and 8 female patients. In all the 20 patients, surgical procedures were undertaken with the retrieval of herniated contents from the thoracic cavity and repair of the diaphragmatic defect. There was no mortality in our series. All the 20 patients were followed-up for a period ranging from 6 months to 5 years (median 3.1 years. Conclusions: Late-presenting CDH can have diverse clinical presentation. Late diagnosis and misdiagnosis can result in significant morbidity and potential mortality if these cases are not managed properly at an appropriate stage. Outcome is favourable if these patients are expeditiously identified and surgically repaired.

  16. Technical bases DWPF Late Washing Facility

    Energy Technology Data Exchange (ETDEWEB)

    Fish, D.L.; Landon, L.F.

    1992-08-10

    A task force recommended that the technical feasibility of a Late Wash' facility be assessed [1]. In this facility, each batch of tetraphenylborate slurry from Tank 49 would be given a final wash to reduce the concentrations of nitrite and radiolysis products to acceptable levels. Laboratory-scale studies have demonstrated that d the nitrite content of the slurry fed to DWPF is reduced to 0.01 M or less (and at least a 4X reduction in concentration of the soluble species is attained), (1) the need for HAN during hydrolysis is eliminated (eliminating the production of ammonium ion during hydrolysis), (2) hydrolysis may be done with a catalyst concentration that will not exceed the copper solubility in glass and (3) the non-polar organic production during hydrolysis is significantly reduced. The first phase of an aggressive research and development program has been completed and all test results obtained to date support the technical feasibility of Late Washing. Paralleling this research and development effort is an aggressive design study directed by DWPF to scope and cost retrofitting the Auxiliary Pump Pit (APP) to enable performing a final wash of each batch of precipitate slurry before R is transferred into the DWPF Soft Processing Cell (SPC). An initial technical bases for the Late Wash Facility was transmitted to DWPF on June 15, 1992. Research and development activities are continuing directed principally at optimization of the cross-f low fitter decontamination methodology and pilot-scale validation of the recommended benzene stripping metodology.

  17. Assessing Fatigue in Late-Midlife

    DEFF Research Database (Denmark)

    Fieo, Robert A; Mortensen, Erik Lykke; Lund, Rikke

    2014-01-01

    late-midlife subjects. Five subdimensions of perceived fatigue were examined in n = 7,233 subjects: general fatigue, physical fatigue, reduced activity, reduced motivation, and mental fatigue. Fatigue burden was compared across age groups (aged 48-52 vs. 57-63) and gender. Mokken item response theory...... was used to investigate dimensionality, monotonicity, and invariant item ordering (IIO). In both age groups, as well as by gender, the Motivation domain presented with weak scalability, suggesting that caution be exercised when interpreting sum scores. For all groupings, the strongest scaling properties...

  18. Late-stage sinking of plutons

    Science.gov (United States)

    Glazner, A.F.; Miller, D.M.

    1997-01-01

    Many granodiorite to diorite plutons in the Great Basin of western North America are surrounded by rim monoclines or anticlines that suggest relative downward movement of the plutons while wall rocks were hot and ductile. We propose that such plutons rise to a level of approximately neutral buoyancy and then founder as their densities increase ??? 40% during crystallization. Late-stage sinking of intermediate to mafic plutons should be common when wall rocks are rich in weak, low-density minerals such as quartz and calcite. Structures related to sinking will overprint those related to initial pluton emplacement and may be mistaken for regional tectonic structures.

  19. Public Schools in Australia from the Late 1970s to the Late 1980s: The Seeds of Change

    Science.gov (United States)

    Barcan, Alan

    2010-01-01

    The period from the late 1970s to the late 1980s were transition years for most public(government) school systems in Australia. A reaction was developing against the neo-progressive and radical (neo-Marxist) innovations of the late 1960s and 1970s such as school-based curricula, activity methods, and "open education". By the early 1980s the…

  20. Cross-sectional analysis of late HAART initiation in Latin America and the Caribbean: late testers and late presenters.

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    Brenda Crabtree-Ramírez

    Full Text Available BACKGROUND: Starting HAART in a very advanced stage of disease is assumed to be the most prevalent form of initiation in HIV-infected subjects in developing countries. Data from Latin America and the Caribbean is still lacking. Our main objective was to determine the frequency, risk factors and trends in time for being late HAART initiator (LHI in this region. METHODOLOGY: Cross-sectional analysis from 9817 HIV-infected treatment-naïve patients initiating HAART at 6 sites (Argentina, Chile, Haiti, Honduras, Peru and Mexico from October 1999 to July 2010. LHI had CD4(+ count ≤200 cells/mm(3 prior to HAART. Late testers (LT were those LHI who initiated HAART within 6 months of HIV diagnosis. Late presenters (LP initiated after 6 months of diagnosis. Prevalence, risk factors and trends over time were analyzed. PRINCIPAL FINDINGS: Among subjects starting HAART (n = 9817 who had baseline CD4(+ available (n = 8515, 76% were LHI: Argentina (56%[95%CI:52-59], Chile (80%[95%CI:77-82], Haiti (76%[95%CI:74-77], Honduras (91%[95%CI:87-94], Mexico (79%[95%CI:75-83], Peru (86%[95%CI:84-88]. The proportion of LHI statistically changed over time (except in Honduras (p≤0.02; Honduras p = 0.7, with a tendency towards lower rates in recent years. Males had increased risk of LHI in Chile, Haiti, Peru, and in the combined site analyses (CSA. Older patients were more likely LHI in Argentina and Peru (OR 1.21 per +10-year of age, 95%CI:1.02-1.45; OR 1.20, 95%CI:1.02-1.43; respectively, but not in CSA (OR 1.07, 95%CI:0.94-1.21. Higher education was associated with decreased risk for LHI in Chile (OR 0.92 per +1-year of education, 95%CI:0.87-0.98 (similar trends in Mexico, Peru, and CSA. LHI with date of HIV-diagnosis available, 55% were LT and 45% LP. CONCLUSION: LHI was highly prevalent in CCASAnet sites, mostly due to LT; the main risk factors associated were being male and older age. Earlier HIV-diagnosis and earlier treatment initiation are needed