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Sample records for baltoscandian ordovician strata

  1. Distribution of the order Proetida (Trilobita in Baltoscandian Ordovician strata

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    Pärnaste, Helje

    2009-03-01

    Full Text Available The trilobite order Proetida forms a minor but important faunal element within the Ordovician strata of Baltoscandia. This review follows the current systematic, taxonomic, and stratigraphical usage and discusses the distribution of these trilobites within the context of the Confacies Belt model. A database of species-level information was derived from numerous publications relating to the Scandinavian and Baltic states and relevant neighbouring regions. Important additional information on stratigraphical occurrences of genera has been derived from glacial erratic boulders (geschiebe from northern Germany and adjacent areas. The representatives from Baltoscandia of three superfamilies, Bathyuroidea, Aulacopleuroidea, and Proetoidea, are listed. The genus level was chosen as the most practicable to plot on the maps, one showing the time interval for the Kukruse Regional Stage (or Global Stage Slice Sa1, the other that for the Pirgu and Porkuni stages (or stage slices Ka4 and Hi1–Hi2. These intervals each show a diversity peak within the ranges of about 30 genera of Proetida and over 70 species from the Ordovician successions of Baltoscandia. Out of these a total of nine genera cross the Ordovician–Silurian boundary.The regional comparisons from within Baltoscandia show differences in facies dependency of certain genera, with possibly also a latitudinal component. During the late Ordovician the faunal resemblance appears to be closest to the neighbouring palaeocontinent Avalonia, suggesting a faunal exchange between or pathways to both continents from elsewhere. Besides climatic and geographical proximity of palaeocontinents, sea-level changes also have to be considered in explaining the distribution of Proetida in Baltoscandia.

  2. Corroded hydrothermal quartz in Ordovician altered volcanic ash beds of the Baltoscandian Region

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    Kiipli, Tarmo

    2009-12-01

    Full Text Available Partly dissolved prismatic quartz crystals have been found in an Upper Ordovician volcanic ash bed of the Vasagård section on Bornholm, Denmark. Similar crystals occur also in a volcanic ash in the Adze Formation of the Aizpute core, Latvia. Although biostratigraphic data are insufficient for the correlation of these findings, the abundant occurrence of this rare form of quartz at Vasagård indicates that it can be reliably used as a correlation criterion in future studies. Partly dissolved prismatic quartz crystals were most likely formed during hydrothermal processes in the volcanic source area.

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

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    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 (test intervals. Pressure transient data collected during the hydraulic tests were analyzed using the well-test simulator nSIGHTS to estimate the hydraulic properties specified as fitting parameters for the tested intervals, quantify parameter uncertainty, and define parameter correlations. Horizontal hydraulic conductivities of the Silurian test intervals range from approximately 4E-14 to 4E-8 m/s. The average horizontal hydraulic conductivities of the Ordovician intervals range from 2E-16 to 2E-10 m/s. The Lower Member of the Cobourg Formation, the proposed host formation of the DGR between 660 and 688 meters below ground surface, was found to have a horizontal hydraulic conductivity of 4E-15 to 3E-14 m/s. The formation pressures inferred from the hydraulic testing, confirmed by long-term monitoring, show that the Upper Ordovician and Middle Ordovician Trenton Group are significantly underpressured relative to a density-compensated hydrostatic 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.

  4. Hydraulic Testing of Silurian and Ordovician Strata at the Bruce Site

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    Beauheim, R. L.; Avis, J. D.; Chace, D. A.; Roberts, R. M.; Toll, N. J.

    2009-05-01

    Ontario Power Generation is proposing a Deep Geologic Repository (DGR) for the long-term management of its Low and Intermediate Level Radioactive Waste (L&ILW) within a Paleozoic-age sedimentary sequence beneath the Bruce Site near Tiverton, Ontario, Canada. The concept envisions that the DGR would be excavated at a depth of approximately 680 m within the Ordovician Cobourg Formation, a massive, dense, argillaceous limestone. A key attribute of the Bruce site is the extremely low permeabilities associated with the thick Ordovician carbonate and argillaceous bedrock formations that will host and enclose the DGR. Such rock mass permeabilities are thought sufficiently low to contribute toward or govern a diffusion-dominated transport regime. To support this concept, hydraulic testing was performed in 2008 and 2009 in two deep boreholes at the proposed repository site, DGR-3 and DGR-4. The hydraulic testing was performed using a straddle-packer tool with a 30.74-m test interval. Sequential tests were performed over the entire open lengths of the boreholes from the F Unit of the Silurian Salina Formation into the Ordovician Gull River Formation, a distance of approximately 635 m. The tests consisted primarily of pressure-pulse tests, with a few slug tests performed in several of the higher permeability Silurian units. The tests are analyzed using the nSIGHTS code, which allows the entire pressure history a test interval has experienced since it was penetrated by the drill bit to be included in the test simulation. nSIGHTS also allows the model fit to the test data to be optimized over an n-dimensional parameter space to ensure that the final solution represents a true global minimum rather than simply a local minimum. The test results show that the Ordovician-age strata above the Coboconk Formation (70+ m below the Cobourg) have average horizontal hydraulic conductivities of 1E-13 m/s or less. Coboconk and Gull River hydraulic conductivities are as high as 1E-11 m

  5. Conodont biostratigraphy in the Early to Middle Ordovician strata of the Oslobreen Group in Ny Friesland, Svalbard

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    Lehnert, Oliver; Stouge, Svend; Brandl, Philipp A.

    2013-01-01

    . Collections of well-preserved conodonts (CAI 1) have been recovered from the Lower to lower Middle Ordovician interval in the region. Eight regional conodont zones are established in this preliminary study of the Oslobreen Group exposed at Hinlopenstretet, NE Svalbard. In ascending order these zones are...... Oepikodus evae becomes frequent and is succeeded by O. intermedius in abundance in the lower Valhallfonna Formation (Olenidsletta Member). The upper strata are characterised by the Periodon-Paroistodus assemblage characteristic for outer shelf and slope environments around Laurentia. In total...

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

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    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.

  7. 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

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    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.

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

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    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.

  9. An evaluation of the carbon sequestration potential of the Cambro-Ordovician Strata of the Illinois and Michigan basins

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    Leetaru, Hannes [Univ. of Illinois, Champaign, IL (United States)

    2014-12-01

    The studies summarized herein were conducted during 2009–2014 to investigate the utility of the Knox Group and St. Peter Sandstone deeply buried geologic strata for underground storage of carbon dioxide (CO2), a practice called CO2 sequestration (CCS). In the subsurface of the midwestern United States, the Knox and associated strata extend continuously over an area approaching 500,000 sq. km, about three times as large as the State of Illinois. Although parts of this region are underlain by the deeper Mt. Simon Sandstone, which has been proven by other Department of Energy-funded research as a resource for CCS, the Knox strata may be an additional CCS resource for some parts of the Midwest and may be the sole geologic storage (GS) resource for other parts. One group of studies assembles, analyzes, and presents regional-scale and point-scale geologic information that bears on the suitability of the geologic formations of the Knox for a CCS project. New geologic and geo-engineering information was developed through a small-scale test of CO2 injection into a part of the Knox, conducted in western Kentucky. These studies and tests establish the expectation that, at least in some locations, geologic formations within the Knox will (a) accept a commercial-scale flow rate of CO2 injected through a drilled well; (b) hold a commercial-scale mass of CO2 (at least 30 million tons) that is injected over decades; and (c) seal the injected CO2 within the injection formations for hundreds to thousands of years. In CCS literature, these three key CCS-related attributes are called injectivity, capacity, and containment. The regional-scale studies show that reservoir and seal properties adequate for commercial-scale CCS in a Knox reservoir are likely to extend generally throughout the Illinois and Michigan Basins. Information distinguishing less prospective subregions from more prospective fairways is included in

  10. Hirnantia sagittifera (Brachiopoda and Mucronaspis mucronata s.l. (Trilobita in the Upper Ordovician of the East Baltic: taxonomy and distribution

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    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.

  11. 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

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    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.

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

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    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, ...

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

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    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.

  14. Geochemistry of Ordovician Keli Group basalts associated with Besshi-type Cu-Zn deposits from the southern Trondheim and Sulitjelma mining districts of Norway

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    Smith, A. D.; Farquhar, J. S.; Smith, P.

    1990-01-01

    Besshi-type volcanogenic Cu-Zn deposits in the Scandinavian Caledonides are hosted by Ordovician metabasalts and clastic sediments of the Storen, Fundsjo and Sulitjelma groups. The basalts are transitional between T-MORB and marginal basin tholeiites in composition and are characterised by Nd and Pb isotopic compositions which overlap the more radiogenic values of Lower Palaeozoic MORB. These features, along with the intercalation of the basalts with tuffs and continentally derived sediments, indicate an epicontinental rift or marginal basin origin, possibly analogous to the present Red Sea and Gulf of Aden rifts. This implies the development of a restricted ocean basin in the north of Iapetus between the Laurentian and Baltoscandian microcontinents during the Cambrian and Early Ordovician.

  15. Long-term effect of the Kärdla crater (Hiiumaa, Estonia) on Late Ordovician carbonate sedimentation

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    Ainsaar, Leho; Suuroja, Kalle; Semidor, Maili

    Kärdla impact crater, 4 km in diameter, was formed in the early Caradoc (Late Ordovician) in the Baltoscandian shelf sea, a sediment-starved temperate-water carbonate basin. The Upper Ordovician post-impact sediments that cover the Kärdla crater are 15-275 m thick. The crater rimwall is composed of three separate basement rises that formed islands or shoals in the Late Ordovician shelf sea and influenced the sedimentation in the surrounding area. The rises provide the means to study the shallow-water sedimentary environments and sea-level history. This may be one of the few cases, where shore environments of the Baltoscandian Ordovician palaeobasin are preserved in the geological record. Lithofacies distribution was studied in the crater area from data of about 100 drillcores. Grain size distribution and composition of the non-carbonate material were analyzed in six core sections in order to reconstruct the history of crater erosion. The post-impact marine deposits lie on a partly redeposited and mixed ejecta layer derived from the Cambrian to Lower Ordovician silici-clastic deposits in the target area. Beds of marine carbonate sediments of Caradoc age, wackestones and mudstones, on-lap on the slope of the crater rim. A shift of sedimentation towards the crater rim during the Caradoc is evidence of a relative sea-level rise, which was a combination of early Caradoc eustatic rise, crater area subsidence, and compaction of pre-impact and impact sediments. The occurrences of coarse sand and gravel in specific stratigraphic intervals reflect the intensity of wave action and sea-level changes in the area. A detailed curve of sea-level changes during Late Ordovician has been constructed and different post-impact sedimentation models are presented for the crater area. The sedimentation pattern changed during the Caradoc as a result of sea-level rise and climatic change. The synchronous appearance of echinoderm bioclastic accumulations in shoal areas in Estonian mainland

  16. Late Ordovician pelecypod faunas from the Cincinnati, Ohio area

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    Frey, R.C.

    1985-01-01

    The distribution of pelecypod faunas in the Late Ordovician strata exposed in the Cincinnati, Ohio area, points to a close relationship between lithofacies type and the life habits of these Ordovician bivalves. Muddy clastic shallow marine facies of Edenian, Maysvillian, and early Richmondian age support faunas dominated by endobyssate filter-feeding species, including a variety of modiomorphids and the genus Ambonychia, plus infaunal filter-feeding orthonotids, and in faunal deposit-feeding palaeotaxodonts. These pelecypod groups occur in claystones with a fauna of calymenid and asaphid trilobites, nautiloids, cyclomyan monoplacophorans, and occasionally crinoids and asterozoans. Younger Richmondian strata in the area are predominantly carbonate platform facies and support pelecypod faunas dominated by robust endobyssate and epibyssate ambonychiids, cyrtodontids, and colpomyids. These pelecypods are associated with diverse assemblage of articulate brachiopods, trepostome ectoprocts, solitary rugose corals, and mollusks in skeletal limestones representing storm-reworked thickets or ramos ectoprocts. This fundamental dichotomy in Late Ordovician pelecypod faunas is recognized not only in the Cincinnati area, but in Late Ordovician strata exposed on Manitoulin Island in Ontario and eastward into Quebec. Reconstructions of the life habits of these pelecypods demonstrates the dominance of the endobyssate mode of life in these Early Paleozoic pelecypods.

  17. End Ordovician extinctions

    DEFF Research Database (Denmark)

    Harper, David Alexander Taylor; Hammarlund, Emma U.; Rasmussen, Christian Mac Ørum

    2014-01-01

    -global anoxia associated with a marked transgression during the Late Hirnantian. Most recently, however, new drivers for the extinctions have been proposed, including widespread euxinia together with habitat destruction caused by plate tectonic movements, suggesting that the end Ordovician mass extinctions were...

  18. 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.

  19. δ13C chemostratigraphy of the Middle and Upper Ordovician succession in the Tartu-453 drillcore, southern Estonia, and the significance of the HICE

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    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.

  20. Conodont biostratigraphy of lower Ordovician rocks, Arbuckle Group, southern Oklahoma

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    Dresbach, R.I.; Ethington, R.L. (Univ. of Missouri, Columbia (USA))

    1989-08-01

    The Arbuckle Group of southern Oklahoma displays the only complete exposure of the shallow-water carbonates that characterize the Lower Ordovician of interior North America. Trilobites have been described from some parts of this sequence and sporadic occurrences of other invertebrates are known, but much of the sequence is sparingly fossiliferous. As a consequence, these magnificent exposures have not contributed notably to continuing efforts toward development of a comprehensive biostratigraphic scheme for the Lower Ordovician of the North American platform. Samples collected at 25-ft intervals through the Arbuckle Group along and adjacent to Interstate Highway 35 on the south flank of the Arbuckle anticline near Ardmore, Oklahoma, produced conodonts in abundances ranging from a few tens to over a thousand elements per kilogram and displaying good to excellent preservation with low CAI. These conodonts document a biostratigraphic continuum that provides a standard for correlation of Lower Ordovician rocks in the subsurface of central US and of the many localized and incomplete outcrops of generally equivalent strata in the Ozark and Upper Mississippi Valley regions. The stratigraphic continuity of the collections makes the I-35 section an ideal standard reference section for graphic correlation of Lower Ordovician rocks containing conodonts of the Mid-Continent Province.

  1. Stratigraphical distribution of the Ordovician conodont Erraticodon Dzik in Argentina

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    Heredia, S.; Carlorosi, J.; Mestre, A.; Soria, T.

    2013-08-01

    Three different species of the Ordovician genus Erraticodon Dzik are described and illustrated. Erraticodon patu Cooper is reported from the Lower-Midde Ordovician strata of the Acoite and Alto del Cóndor formations. E. cf. Erraticodon balticus and Erraticodon hexianensis from Middle Ordovician carbonate deposits of the San Juan Formation are analyzed and compared to specimens of these species from Australia, China, Newfoundland, and Baltica. E. patu and E. hexianensis are recorded for first time in the San Juan Formation of Precordillera. The elements of E. cf. E. balticus resemble closely E. balticus Dzik but lack the important denticle on the posterior process of the S elements. An evaluation of the stratigraphic occurrences of these species relative to those of key Lower and Middle Ordovician conodont species such as Trapezognathus diprion Lindström, Oepikodus intermedius Serpagli, Baltoniodus triangularis (Lindström), Baltoniodus navis Lindström, Yangtzeplacognathus crassus (Chen and Zhang) and Eoplacognathus pseudoplanus (Viira) indicates they value for biostratigraphic correlation.

  2. Upper Ordovician-Lower Silurian shelf sequences of the Eastern Great Basin: Barn Hills and Lakeside Mountains, Utah

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    Harris, M.T. (Univ. of Wisconsin, Milwaukee, WI (United States). Dept. of Geosciences); Sheehan, P.M. (Milwaukee Public Museum, WI (United States). Dept of Geology)

    1993-04-01

    Detailed stratigraphic sections through Upper Ordovician-Lower Silurian shelf strata of the Eastern Great Basin were measured in two Utah localities, Barn Hills (Confusion Range) and Lakeside Mountains. Six major subfacies occur in these strata: mud-cracked and crinkly laminated subfacies, Laminated mudstone subfacies, cross-bedded grainstone subfacies, cross-laminated packstone subfacies, grainy bioturbated subfacies, muddy bioturbated subfacies, and thalassinoides burrowed subfacies. These occur in 1--10 m thick cycles in three facies: muddy cyclic laminite facies (tidal flats), cross-bedded facies (subtidal shoals), and bioturbated facies (moderate to low-energy shelf). The vertical facies succession, stacking patterns of meter-scale cycles, and exposure surfaces define correlatable sequences. The authors recognize four Upper Ordovician sequences (Mayvillian to Richmondian). An uppermost Ordovician (Hirnantian) sequence is missing in these sections but occurs basinward. Lower Silurian sequences are of early Llandoverian (A), middle Llandoverian (B), early late Llandoverian (C1--C3), late late Llandoverian (C4--C5), latest Llandoverian (C6) to early Wenlock age. In general, Upper Ordovician and latest Llandoverian-Wenlockian facies are muddier than intervening Llandoverian facies. The shift to muddier shelf facies in latest Llandoverian probably corresponds to the development of a rimmed shelf. The sequence framework improves correlation of these strata by combining sedimentologic patterns with the biostratigraphic data. For example, in the Lakesides, the Ordovician-Silurian boundary is shifted 37 m downward from recent suggestions. In addition, the sequence approach highlights intervals for which additional biostratigraphic information is needed.

  3. Thermal maturity patterns in the Ordovician and Devonian of Pennsylvania using conodont color alteration index (CAI) and vitrinite reflectance (%Ro)

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    Repetski, J.E.; Ryder, R.T.; Harper, J.A.; Trippi, M.H.

    2006-01-01

    This new series of maps enhances previous thermal maturity maps in Pennsylvania by establishing: 1) new subsurface CAI data points for the Ordovician and Devonian and 2) new %Ro and Rock Eval subsurface data points for Middle and Upper Devonian black shale units. Thermal maturity values for the Ordovician and Devonian strata are of major interest because they contain the source rocks for most of the oil and natural gas resources in the basin. Thermal maturity patterns of the Middle Ordovician Trenton Group are evaluated here because they closely approximate those of the overlying Ordovician Utica Shale that is believed to be the source rock for the regional oil and gas accumulation in Lower Silurian sandstones and for natural gas fields in fractured dolomite reservoirs of the Ordovician Black River-Trenton Limestones. Improved CAI-based thermal maturity maps of the Ordovician are important to identify areas of optimum gas generation from the Utica Shale and to provide constraints for interpreting the origin of oil and gas in the Lower Silurian regional accumulation and Ordovician Black River-Trenton fields. Thermal maturity maps of the Devonian will better constrain burial history-petroleum generation models of the Utica Shale, as well as place limitations on the origin of regional oil and gas accumulations in Upper Devonian sandstone and Middle to Upper Devonian black shale.

  4. Thermal maturity patterns (CAI and %R) in the Ordovician and Devonian rocks of the Appalachian basin in Pennsylvania

    Science.gov (United States)

    Repetski, John E.; Ryder, Robert T.; Harper, John A.; Trippi, Michael H.

    2002-01-01

    The objective of this study is to enhance existing thermal maturity maps in Pennsylvania by establishing: 1) new subsurface CAI data points for the Ordovician and Devonian and 2) new %Ro and Rock Eval subsurface data points for Middle and Upper Devonian black shale units. Thermal maturity values for the Ordovician and Devonian strata are of major interest because they contain the source rocks for most of the oil and natural gas resources in the basin. Thermal maturity patterns of the Middle Ordovician Trenton Group are evaluated here because they closely approximate those of the overlying Ordovician Utica Shale that is believed to be the source rock for the regional oil and gas accumulation in Lower Silurian sandstones (Ryder and others, 1998) and for natural gas fields in fractured dolomite reservoirs of the Ordovician Black River-Trenton Limestones. Improved CAI-based thermal maturity maps of the Ordovician are important to identify areas of optimum gas generation from the Utica Shale and to provide constraints for interpreting the origin of oil and gas in the Lower Silurian regional accumulation and Ordovician Black River-Trenton fields. Thermal maturity maps of the Devonian will better constrain burial history-petroleum generation models of the Utica Shale, as well as place limitations on the origin of regional oil and gas accumulations in Upper Devonian sandstone and Middle to Upper Devonian black shale.

  5. Thermal maturity patterns (CAI and %Ro) in the Ordovician and Devonian rocks of the Appalachian basin in West Virginia

    Science.gov (United States)

    Repetski, John E.; Ryder, Robert T.; Avary, Katharine Lee; Trippi, Michael H.

    2005-01-01

    The objective of this study is to enhance existing thermal maturity maps in West Virginia by establishing: 1) new subsurface CAI data points for the Ordovician and Devonian and 2) new %Ro and Rock Eval subsurface data points for Middle and Upper Devonian black shale units. Thermal maturity values for the Ordovician and Devonian strata are of major interest because they contain the source rocks for most of the oil and natural gas resources in the basin. Thermal maturity patterns of the Middle Ordovician Trenton Limestone are evaluated here because they closely approximate those of the overlying Ordovician Utica Shale that is believed to be the source rock for the regional oil and gas accumulation in Lower Silurian sandstones (Ryder and others, 1998) and for natural gas fields in fractured dolomite reservoirs of the Ordovician Black River-Trenton Limestones. Improved CAI-based thermal maturity maps of the Ordovician are important to identify areas of optimum gas generation from the Utica Shale and to provide constraints for interpreting the origin of oil and gas in the Lower Silurian regional accumulation and Ordovician Black River-Trenton fields. Thermal maturity maps of the Devonian will better constrain burial history-petroleum generation models of the Utica Shale, as well as place limitations on the origin of regional oil and gas accumulations in Upper Devonian sandstone and Middle to Upper Devonian black shale.

  6. 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.

  7. Redox fluctuations in the Early Ordovician oceans

    DEFF Research Database (Denmark)

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

    2017-01-01

    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...

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

    OpenAIRE

    Zhaoming, Wang; Haijun, Yang; Yingmin, Qi; Yongquan, Chen; Yanlong, Xu

    2014-01-01

    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 ...

  9. Late Ordovician brachiopods from eastern North Greenland

    DEFF Research Database (Denmark)

    Mac Ørum Rasmussen, Christian

    2013-01-01

    Late Ordovician rhynchonelliformean brachiopods, typical of the North American Red River fauna, are found sporadically in the BOrglum River Formation of the Centrum SO area, Kronprins Christian Land, eastern North Greenland. The geographical distribution of this characteristic brachiopod fauna...... invasion of migrants from Baltica that arrived later during the Hirnantian. The offshore migration of this atypical Hiscobeccus fauna likely demonstrates the path of warm-water currents as the Centrum SO locality was located at the equator during the Late Ordovician....

  10. Hydrocarbon potential of Ordovician and Silurian rocks. Siljan Region (Sweden)

    Energy Technology Data Exchange (ETDEWEB)

    Berner, U. [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany); Lehnert, O. [Erlangen-Nuernberg Univ., Erlangen (Germany); Meinhold, G. [Goettingen Univ. (Germany)

    2013-08-01

    Hydrocarbon exploration in the vicinity of Europe's largest impact structure (Siljan, Central Sweden) focused for years on abiogenic concepts and largely neglected state of the art knowledge on hydrocarbon generation via thermal decomposition of organic matter. In our study we use sedimentary rocks obtained from three drill sites (Mora001, Stumsnaes 1 and Solberga 1) within the ring structure around the central uplift to investigate the hydrocarbon potential of Ordovician and Silurian strata of the region and also for comparison with the shale oil and gas potential of age equivalent rocks of the Baltic Sea. Elemental analyses provided information on concentrations of carbonate and organic carbon, total sulfur as well as on the composition of major and minor elements of the sediments. The data has been used to evaluate the depositional environment and possible diagenetic alterations of the organic matter. RockEval pyrolysis and solvent hydrocarbon extraction gave insight into the hydrocarbon generation potential and the type and thermal maturity of the sediments. From the geochemistry data of the studied wells it is obvious that changes of depositional environments (lacustrine - marine) have occurred during Ordovician and Silurian times. Although, the quality of the organic matter has been influenced in marine and brackish environments through sulfate reduction, we observe for a number of marine and lacustrine sediments a good to excellent preservation of the biological precursors which qualify the sediments as hydrocarbon source rocks (Type II kerogens). Lacustrine source rocks show a higher remaining hydrocarbon potential (up to {proportional_to}550 mg HC per g C{sub org}) than those of marine or brackish environments. Our investigations indicate that the thermal maturity of organic matter of the drill sites has reached the initial stage of oil generation. However, at Mora001 some of the sediments were stained with oil indicating that hydrocarbons have

  11. 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

  12. Trace metal occurrences in acid-insoluble residues of the Ordovician Galena Group, southeastern Minnesota

    Energy Technology Data Exchange (ETDEWEB)

    Lively, R.S.; Mossler, J.H.; Morey, G.B. (Minnesota Geological Survey, St. Paul, MN (United States)); Hauck, S.A. (Univ. of Minnesota, Duluth, MN (United States). Natural Resources Research Inst.)

    1993-03-01

    Regional geochemical, studies on insoluble residues from Paleozoic carbonate rocks have become an integral part of the search for new Upper Mississippi Valley-type mineral deposits in the northern Midcontinent. The authors have extended these studies to southeastern Minnesota, an area well to the north of known lead-zinc deposits of commercial size and grade. In this region, a thin sequence of Upper Cambrian to Middle Ordovician strata unconformably overlies a complex Precambrian basement. More than 500 samples of limestone and dolomite from 40 drill holes and outcrops were analyzed for 29 related trace elements. Preliminary interpretations are based on the analysis of 380 samples of the Ordovician Galena Group from 37 localities. Results indicate that anomalous concentrations of Pb, Cu, zn, As, Cd, and Ni are confined to the southern half of the Galena subgroup area and extend less than 30 miles north of the Iowa border. The anomalous areas, as well as saddles between the, have a distinct northwest trend, coincident with structural features previously recognized in the Precambrian basement. The spatial relationships of the anomalies and the lack of direct correlation imply deposition from fluids moving north out of the main lead-zinc district along structural pathways. The lack of significant anomalies in the northern part of the subcrop area implies northwest weakening of the forces driving the metal-bearing fluids, as well as a decrease over distance in the absolute metal content of the migrating fluids.

  13. Cornulitids (tubeworms) from the Late Ordovician Hirnantia fauna of Morocco

    Science.gov (United States)

    Gutiérrez-Marco, Juan Carlos; Vinn, Olev

    2018-01-01

    Two species of cornulitids, Cornulites gondwanensis sp. nov. and C. aff. shallochensis Reed are described from the Hirnantian of Morocco, within an assemblage representative of the Hirnantia brachiopod fauna occurring near the Ordovician South Pole. The dominance of aggregated and solitary free forms could be explained by particular sedimentary environments preceding the Hirnantian glaciation and the latest Ordovician Extinction Event. The diversity of cornulitids in the Late Ordovician of Gondwana and related terranes was relatively low, and less diverse than the cornulitids of Laurentia and Baltica. Hirnantian cornulitids from Morocco do not resemble Late Ordovician cornulitids of Baltica and Laurentia. Moroccan cornulitids seem to be closely allied to some older Gondwanan cornulitids, especially Sardinian ones. They resemble species described from the Late Ordovician and Llandovery of Scotland suggesting a palaeobiogeographic link.

  14. 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...

  15. Maps showing petroleum exploration intensity and production in major Cambrian to Ordovician reservoir rocks in the Anadarko Basin

    Science.gov (United States)

    Henry, Mitch; Hester, Tim

    1996-01-01

    The Anadarko basin is a large, deep, two-stage Paleozoic basin (Feinstein, 1981) that is petroleum rich and generally well explored. The Anadarko basin province, a geogrphic area used here mostly for the convenience of mapping and data management, is defined by political boundaries that include the Anadarko basin proper. The boundaries of the province are identical to those used by the U.S. Geological Survey (USGS) in the 1995 National Assessment of United Stated Oil and Gas Resources. The data in this report, also identical to those used in the national assessment, are from several computerized data bases including Nehring Research Group (NRG) Associates Inc., Significant Oil and Gas Fields of the United States (1992); Petroleum Information (PI), Inc., Well History Control System (1991); and Petroleum Information (PI), Inc., Petro-ROM: Production data on CD-ROM (1993). Although generated mostly in response to the national assessment, the data presented here arc grouped differently and arc displayed and described in greater detail. In addition, the stratigraphic sequences discussed may not necessarily correlate with the "plays" of the 1995 national assessment. This report uses computer-generated maps to show drilling intensity, producing wells, major fields, and other geologic information relevant to petroleum exploration and production in the lower Paleozoic part of the Anadarko basin province as defined for the U.S. Geological Survey's 1995 national petroleum assessment. Hydrocarbon accumulations must meet a minimum standard of 1 million barrels of oil (MMBO) or 6 billion cubic feet of gas (BCFG) estimated ultimate recovery to be included in this report as a major field or revoir. Mapped strata in this report include the Upper Cambrian to Lower Ordovician Arbuckle and Low Ordovician Ellenburger Groups, the Middle Ordovician Simpson Group, and the Middle to Upper Ordovician Viola Group.

  16. Detrital zircon geochronology of pre- and syncollisional strata, Acadian orogen, Maine Appalachians

    Science.gov (United States)

    Bradley, Dwight C.; O'Sullivan, Paul B.

    2017-01-01

    The Central Maine Basin is the largest expanse of deep-marine, Upper Ordovician to Devonian metasedimentary rocks in the New England Appalachians, and is a key to the tectonics of the Acadian Orogeny. Detrital zircon ages are reported from two groups of strata: (1) the Quimby, Rangeley, Perry Mountain and Smalls Falls Formations, which were derived from inboard, northwesterly sources and are supposedly older; and (2) the Madrid, Carrabassett and Littleton Formations, which were derived from outboard, easterly sources and are supposedly younger. Deep-water deposition prevailed throughout, with the provenance shift inferred to mark the onset of foredeep deposition and orogeny. The detrital zircon age distribution of a composite of the inboard-derived units shows maxima at 988 and 429 Ma; a composite from the outboard-derived units shows maxima at 1324, 1141, 957, 628, and 437 Ma. The inboard-derived units have a greater proportion of zircons between 450 and 400 Ma. Three samples from the inboard-derived group have youngest age maxima that are significantly younger than the nominal depositional ages. The outboard-derived group does not share this problem. These results are consistent with the hypothesised provenance shift, but they signal potential problems with the established stratigraphy, structure, and (or) regional mapping. Shallow-marine deposits of the Silurian to Devonian Ripogenus Formation, from northwest of the Central Maine Basin, yielded detrital zircons featuring a single age maximum at 441 Ma. These zircons were likely derived from a nearby magmatic arc now concealed by younger strata. Detrital zircons from the Tarratine Formation, part of the Acadian foreland-basin succession in this strike belt, shows age maxima at 1615, 980 and 429 Ma. These results are consistent with three episodes of zircon recycling beginning with the deposition of inboard-derived strata of the Central Maine Basin, which were shed from post-Taconic highlands located to the

  17. Origin of natural gas from the Ordovician paleo-weathering crust and gas-filling model in Jingbian gas field, Ordos basin, China

    Science.gov (United States)

    Liu, Quanyou; Chen, Mengjin; Liu, Wenhui; Li, Jian; Han, Pinlong; Guo, Yanru

    2009-06-01

    The Ordos basin, the second largest natural gas producing basin in China, is one of the most tectonically stable sedimentary basins favorable to natural gas generation and preservation. The origin and potential source of the Jingbian gas field, one of the five giant gas fields in the basin containing the Ordovician paleo-weathering crust as reservoir strata, remains unclear. The question is whether gas is generated from Carboniferous-Permian coal measures or Ordovician carbonates. This study provides abundant gas geochemical evidence which clarifies its origin and source. Among 82 natural gas samples collected from the Ordovician paleo-weathering crust in the Jingbian gas field, C 1-C 4 gaseous hydrocarbons are dominant with low amounts of non-hydrocarbons (CO 2, H 2S and N 2). The content of C 1-C 4 ranges from 79.26 to 99.93% with a gas dryness (C 1/C 1-4) of 0.981-0.999, suggesting that natural gases are dry and possibly originate from a high to over-mature source. The carbon isotopic compositions of methane and its homologues in natural gases from the Ordovician paleo-weathering crust vary widely, with δ 13C 1, δ 13C 2 and δ 13C 3 values of -38.9‰ to -29.1‰, -37.5‰ to -22.2‰ and -30.0 to -20.9‰, respectively. The δ 13C 2 and δ 13C 3 values in the Jingbian gas field are much more negative than those of typical coal-type gas in Sulige, Wushenqi, Yulin, Daniudi, and Kela2 gas fields. The carbon isotopic signature suggests that the natural gas in the Ordovician paleo-weathering crust in the Jingbian gas field most likely originates from Ordovician carbonates containing sapropelic organic matter. The measured δD values of methane range from -177 to -155‰ and support our hypothesis of the natural gases originating from marine sapropelic organic matter. The thermal maturity of the natural gases in the Ordovician paleo-weathering crust is at a high- to over-mature stage, suggesting that the gases originated from secondary cracking of oil and gas at

  18. Environmental conditions and microbial community structure during the Great Ordovician Biodiversification Event; a multi-disciplinary study from the Canning Basin, Western Australia

    Science.gov (United States)

    Spaak, Gemma; Edwards, Dianne S.; Foster, Clinton B.; Pagès, Anais; Summons, Roger E.; Sherwood, Neil; Grice, Kliti

    2017-12-01

    The Great Ordovician Biodiversification Event (GOBE) is regarded as one of the most significant evolutionary events in the history of Phanerozoic life. The present study integrates palynological, petrographic, molecular and stable isotopic (δ13C of biomarkers) analyses of cores from four boreholes that intersected the Goldwyer Formation, Canning Basin, Western Australia, to determine depositional environments and microbial diversity within a Middle Ordovician epicontinental, tropical sea. Data from this study indicate lateral and temporal variations in lipid biomarker assemblages extracted from Goldwyer Formation rock samples. These variations likely reflect changing redox conditions between the upper (Unit 4) and lower (Units 1 + 2) Goldwyer, which is largely consistent with existing depositional models for the Goldwyer Formation. Cryptospores were identified in Unit 4 in the Theia-1 well and are most likely derived from bryophyte-like plants, making this is the oldest record of land plants in Australian Middle Ordovician strata. Biomarkers in several samples from Unit 4 that also support derivation from terrestrial organic matter include benzonaphthofurans and δ13C-depleted mid-chain n-alkanes. Typical Ordovician marine organisms including acritarchs, chitinozoans, conodonts and graptolites were present in the lower and upper Goldwyer Formation, whereas the enigmatic organism Gloeocapsomorpha prisca (G. prisca) was only detected in Unit 4. The correlation of a strong G. prisca biosignature with high 3-methylhopane indices and 13C depleted G. prisca-derived chemical fossils (biomarkers) is interpreted to suggest an ecological relationship between methanotrophs and G. prisca. This research contributes to a greater understanding of Ordovician marine environments from a molecular perspective since few biomarker studies have been undertaken on age-equivalent sections. Furthermore, the identification of the oldest cryptospores in Australia and their corresponding

  19. Phylogenetic paleobiogeography of Late Ordovician Laurentian brachiopods

    Directory of Open Access Journals (Sweden)

    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.

  20. Deposits of hydrocarbons in clayey strata. [Siberia

    Energy Technology Data Exchange (ETDEWEB)

    Gurari, F.G.

    1981-01-01

    Four strata of domanicites participating in the structure of the covering of the Russian and Siberian platforms and the Western Siberian plate are described. Some of their physical and chemical parameters, peculiarities of fascial characteristics are also described. Conditions of accumulation of domanicites, and also the arising in them of deposits of hydrocarbons are examined. Methods of charting zones and regions of most interest for the setting up of prospecting operations are noted.

  1. 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

  2. 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.

  3. A paired apatite and calcite clumped isotope thermometry approach to estimating Cambro-Ordovician seawater temperatures and isotopic composition

    Science.gov (United States)

    Bergmann, Kristin D.; Finnegan, Seth; Creel, Roger; Eiler, John M.; Hughes, Nigel C.; Popov, Leonid E.; Fischer, Woodward W.

    2018-03-01

    The secular increase in δ18O values of both calcitic and phosphatic marine fossils through early Phanerozoic time suggests either that (1) early Paleozoic surface temperatures were high, in excess of 40 °C (tropical MAT), (2) the δ18O value of seawater has increased by 7-8‰ VSMOW through Paleozoic time, or (3) diagenesis has altered secular trends in early Paleozoic samples. Carbonate clumped isotope analysis, in combination with petrographic and elemental analysis, can deconvolve fluid composition from temperature effects and therefore determine which of these hypotheses best explain the secular δ18O increase. Clumped isotope measurements of a suite of calcitic and phosphatic marine fossils from late Cambrian- to Middle-late Ordovician-aged strata-the first paired fossil study of its kind-document tropical sea surface temperatures near modern temperatures (26-38 °C) and seawater oxygen isotope ratios similar to today's ratios.

  4. Oxygenation as a driver of the Great Ordovician Biodiversification Event

    Science.gov (United States)

    Edwards, Cole T.; Saltzman, Matthew R.; Royer, Dana L.; Fike, David A.

    2017-12-01

    The largest radiation of Phanerozoic marine animal life quadrupled genus-level diversity towards the end of the Ordovician Period about 450 million years ago. A leading hypothesis for this Great Ordovician Biodiversification Event is that cooling of the Ordovician climate lowered sea surface temperatures into the thermal tolerance window of many animal groups, such as corals. A complementary role for oxygenation of subsurface environments has been inferred based on the increasing abundance of skeletal carbonate, but direct constraints on atmospheric O2 levels remain elusive. Here, we use high-resolution paired bulk carbonate and organic carbon isotope records to determine the changes in isotopic fractionation between these phases throughout the Ordovician radiation. These results can be used to reconstruct atmospheric O2 levels based on the O2-dependent fractionation of carbon isotopes by photosynthesis. We find a strong temporal link between the Great Ordovician Biodiversification Event and rising O2 concentrations, a pattern that is corroborated by O2 models that use traditional carbon-sulfur mass balance. We conclude that that oxygen levels probably played an important role in regulating early Palaeozoic biodiversity levels, even after the Cambrian Explosion.

  5. Lithostratigraphic, conodont, and other faunal links between lower Paleozoic strata in northern and central Alaska and northeastern Russia

    Science.gov (United States)

    Dumoulin, Julie A.; Harris, Anita G.; Gagiev, Mussa; Bradley, Dwight C.; Repetski, John E.

    2002-01-01

    Lower Paleozoic platform carbonate strata in northern Alaska (parts of the Arctic Alaska, York, and Seward terranes; herein called the North Alaska carbonate platform) and central Alaska (Farewell terrane) share distinctive lithologic and faunal features, and may have formed on a single continental fragment situated between Siberia and Laurentia. Sedimentary successions in northern and central Alaska overlie Late Proterozoic metamorphosed basement; contain Late Proterozoic ooid-rich dolostones, Middle Cambrian outer shelf deposits, and Ordovician, Silurian, and Devonian shallow-water platform facies, and include fossils of both Siberian and Laurentian biotic provinces. The presence in the Alaskan terranes of Siberian forms not seen in wellstudied cratonal margin sequences of western Laurentia implies that the Alaskan rocks were not attached to Laurentia during the early Paleozoic.The Siberian cratonal succession includes Archean basement, Ordovician shallow-water siliciclastic rocks, and Upper Silurian–Devonian evaporites, none of which have counterparts in the Alaskan successions, and contains only a few of the Laurentian conodonts that occur in Alaska. Thus we conclude that the lower Paleozoic platform successions of northern and central Alaska were not part of the Siberian craton during their deposition, but may have formed on a crustal fragment rifted away from Siberia during the Late Proterozoic. The Alaskan strata have more similarities to coeval rocks in some peri-Siberian terranes of northeastern Russia (Kotelny, Chukotka, and Omulevka). Lithologic ties between northern Alaska, the Farewell terrane, and the peri-Siberian terranes diminish after the Middle Devonian, but Siberian afµnities in northern and central Alaskan biotas persist into the late Paleozoic.

  6. 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...

  7. Stratigraphy of the cambo-ordovician succession in Illnois

    Energy Technology Data Exchange (ETDEWEB)

    Lasemi, Yaghoob; Khorasgani, Zohreh; Leetaru, Hannes

    2014-09-30

    The Upper Cambrian through Lower Ordovician succession (Sauk II-III sequences) in the Illinois Basin covers the entire state of Illinois and most of the states of Indiana and Kentucky. To determine lateral and vertical lithologic variations of the rocks within the Cambro-Ordovician deposits that could serve as reservoir or seal for CO2 storage, detailed subsurface stratigraphic evaluation of the succession in Illinois was conducted. The Cambro-Ordovician succession in the Illinois Basin consists of mixed carbonate-siliciclastic deposits. Its thickness ranges from nearly 800 feet in the extreme northwest to nearly 8000 feet in the Reelfoot Rift in the extreme southeastern part of the state. In northern and central Illinois, the Cambro-Ordovician rocks are classified as the Cambrian Knox and the Ordovician Prairie du Chien Groups, which consist of alternating dolomite and siliciclastic units. In the southern and deeper part of the Illinois Basin, the Cambro-Ordovician deposits consist chiefly of fine to coarsely crystalline dolomite capped by the Middle Ordovician Everton Formation. Detailed facies analysis indicates that the carbonate units consist mainly of mudstone to grainstone facies (fossiliferous/oolitic limestone and dolomite) with relics of bioclasts, ooids, intraclasts and peloids recording deposition on a shallow marine ramp setting. The dominant lithology of the Knox and the overlying Prairie du Chien Group is fine to coarsely crystalline, dense dolomite. However, porous and permeable vugular or fractured/cavernous dolomite intervals that grade to dense fine to coarsely crystalline dolomite are present within the dolomite units. Several hundred barrels of fluid were lost in some of these porous intervals during drilling, indicating high permeability. The sandstone intervals are porous and permeable and are texturally and compositionally mature. The permeable sandstone and porous dolomite intervals are laterally extensive and could serve as important

  8. Pathways and mechanisms of Late Ordovician (Katian faunal migrations of Laurentia and Baltica

    Directory of Open Access Journals (Sweden)

    Adriane R. Lam

    2015-02-01

    Full Text Available Late Ordovician strata within the Cincinnati Basin record a mass faunal migration event during the C4 and C5 depositional sequences. The geographic source region for the invaders and the paleoceanographic conditions that facilitated dispersal into the Cincinnati Basin has previously been poorly understood. Using Parsimony Analysis of Endemicity, biogeographic relationships among Laurentian and Baltic basins were analyzed for each of the C1–C5 depositional sequences to identify dispersal paths. The results support multiple dispersal pathways, including three separate dispersal events between Baltica and Laurentia. Within Laurentia, results support dispersal pathways between areas north of the Transcontinental Arch into the western Midcontinent, between the Upper Mississippi Valley into the Cincinnati Basin, and between the peri-cratonic Scoto-Appalachian Basin and the Cincinnati Basin. These results support the hypothesis that invasive taxa entered the Cincinnati Basin via multiple dispersal pathways and that the equatorial Iapetus current facilitated dispersal of organisms from Baltica to Laurentia. Within Laurentia, surface currents and large storms moving from northeast to southwest likely influenced the dispersal of organisms. Larval states were characterized for the Richmondian invaders, and most invaders were found to have had planktotrophic planktic larvae. These self-feeding larvae have high dispersal potential, which – in conjunction with oceanographic and climatic conditions – enabled long-distance dispersal and interbasinal species migrations.

  9. 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...... the 'Great Ordovician Biodiversification Event' part of a long-term late Proterozoic and Early Palaeozoic radiation, that in part is expressed by the fossil record as the 'Cambrian Explosion.' A significant diversification of different groups of the plankton is observed in the late Cambrian-Early Ordovician...

  10. Study on the Rule of Super Strata Movement and Subsidence

    Science.gov (United States)

    Yao, Shunli; Yuan, Hongyong; Jiang, Fuxing; Chen, Tao; Wu, Peng

    2018-01-01

    The movement of key strata is related to the safety of the whole earth’s surface for coal mining under super strata. Based on the key strata theory, the paper comprehensively analyzes the characteristics of the subsidence before and after the instability of the super strata by studing through FLAC3D and microseismic dynamic monitoring of the surface rock movement observation. The stability of the super strata movement is analyzed according to the characteristic value of the subsidence. The subsidence law and quantitative indexes under the control of the super rock strata that provides basis for the prevention and control of surface risk, optimize mining area and face layout and reasonably set mining boundary around mining area. It provides basis for the even growth of mine safety production and regional public safety.

  11. The earliest cornulitid on the internal surface of the illaenid pygidium from the Middle Ordovician of Estonia

    Directory of Open Access Journals (Sweden)

    Olev Vinn

    2017-10-01

    Full Text Available The earliest cornulitid Cornulites sp. appears in the Darriwilian (Lasnamägi Regional Stage of Estonia. Internal annulation is present in all Middle Ordovician cornulitids and could be a plesiomorphic character for the group. The encrusted trilobites are rare in the Ordovician of Estonia. Illaenid pygidia and cranidia were encrusted by cornulitids and trepostome bryozoans. The encrustation of both Middle Ordovician and Late Ordovician trilobites took place post mortem. The studied hard substrate communities of Middle Ordovician and Late Ordovician trilobite pygidia and cranidia are typical of the Ordovician.

  12. Element distribution patterns in the ordovician Galena group, Southeastern Minnesota: Indicators of fluid flow and provenance of terrigenous material

    Science.gov (United States)

    Lively, R.S.; Morey, G.B.; Mossler, J.H.

    1997-01-01

    As part of a regional geochemical investigation of lower Paleozoic strata in the Hollandale embayment of southeastern Minnesota, elemental concentrations in acid-insoluble residues were determined for carbonate rock in the Middle Ordovician Galena Group. Elemental distribution patterns within the insoluble residues, particularly those of Ti, Al, and Zr, show that the Wisconsin dome and the Wisconsin arch, which contributed sediment to the embayment prior to Galena time, continued as weak sources of sediment during this period. In contrast, trace metals commonly associated with Mississippi Valley-type lead-zinc mineralization, including Pb, Zn, Cu, Ag, Ni, Co, As, and Mo, show dispersal patterns that are independent of those associated with primary depositional phenomena. These trace metals are concentrated in southern Minnesota in carbonate rocks near the interface between limestone- and dolostone-dominated strata. Dispersal patterns imply that the metals were carried by a north-flowing regional ground-water system. The results show that the geochemical attributes of insoluble residues can be used to distinguish provenance and transport directions of primary sediments within a depositional basin from effects of subsequent regional ground-water flow systems.

  13. 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...

  14. Malaria in three epidemiological strata in Mauritania.

    Science.gov (United States)

    Ouldabdallahi Moukah, Mohamed; Ba, Ousmane; Ba, Hampaté; Ould Khairy, Mohamed Lemine; Faye, Ousmane; Bogreau, Hervé; Simard, Frédéric; Basco, Leonardo K

    2016-04-12

    Malaria epidemiology in Mauritania has been characterized on the basis of epidemiological strata, defined by climatic and geographic features, which divide the country into three zones: Sahelian zone, Sahelo-Saharan transition zone, and Saharan zone. The association between geographic stratification and malaria transmission was assessed through a series of parasitological and entomological surveys. Surveys were conducted during the 'cool' dry season in 2011, 'hot' dry season in 2012, and rainy season in 2013 in a total of 12 sentinel sites. Finger-prick capillary blood samples were collected from children aged 2-9 years old in randomly selected households for microscopic examination and rapid diagnostic test for malaria. Adult mosquitoes were sampled by pyrethrum spray catch and CDC light traps and identified using morphological keys and molecular tools. Of 3445 children included, 143 (4.15 %) were infected with malaria parasites including Plasmodium falciparum (n = 71, 2.06 %), Plasmodium vivax (57, 1.65 %), P. falciparum-P. vivax (2, 0.06 %), Plasmodium ovale (12, 0.35 %), and Plasmodium malariae (1, 0.03 %). A large majority of P. falciparum infections were observed in the Sahelo-Saharan zone. Malaria prevalence (P Mauritania. However, the Sahelian zone had the lowest malaria prevalence, while the Sahelo-Saharan zone had the highest malaria burden. Local changes due to anthropogenic factors (i.e., human migration, urbanization, malaria interventions) should be considered in order to optimize the control strategy.

  15. On Some Theoretical Issues about Historical Strata Analysis

    OpenAIRE

    Pan Wuyun

    2016-01-01

    This paper is a comprehensive discussion about a few theoretical issues of historical strata analysis, that is, uniformitarianism and neogramarian hypothesis, catastrophism and borrowing, wendu and baidu readings, native stratum, identification of loan strata and native stratum, influence and borrowing, and real time and apparent time.

  16. On Some Theoretical Issues about Historical Strata Analysis

    Directory of Open Access Journals (Sweden)

    Pan Wuyun

    2016-12-01

    Full Text Available This paper is a comprehensive discussion about a few theoretical issues of historical strata analysis, that is, uniformitarianism and neogramarian hypothesis, catastrophism and borrowing, wendu and baidu readings, native stratum, identification of loan strata and native stratum, influence and borrowing, and real time and apparent time.

  17. 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.

  18. Paleomagnetism of Latest Cambrian-Early Ordovician and Latest Cretaceous-Early Tertiary rocks of the Florida Mountains, southwest New Mexico

    Science.gov (United States)

    Geissman, John W.; Jackson, Mike; Harlan, Steve S.; van der Voo, Rob

    1991-04-01

    Paleomagnetic investigations have been carried out on latest Cambrian to Early Ordovician alkaline intrusions, their contact intermediate to mafic composition metaigneous rocks, and overlying lower Paleozoic and early Tertiary strata in the Florida Mountains, southwestern New Mexico. A well-defined, predominantly normal polarity magnetization of high median destructive induction and high, usually discrete laboratory unblocking temperatures is isolated from sites in metaigneous rocks in contact with syenites exposed on the northwestern flank of this late Cenozoic uplift. Combinations of stable endpoint and planar data are used in data analysis at the site level (D = 262°, I = -30°, α95 = 10°, k = 12; N = 22 site means). In addition to the presence of reverse polarity magnetizations at two sites, the dispersion of site mean directions in these rocks (VGP angular standard deviation of 19.6°) suggests that considerable variation of the geomagnetic field has been averaged. After correction for a combination of early Tertiary (Laramide) deformation and late Tertiary Basin-Range block tilting, this magnetization gives a paleomagnetic pole at 6°S, 169°E and is interpreted to have been acquired soon after intrusion of alkaline plutons at 503±10 Ma, based on published U-Pb zircon isotopic age determinations. A lack of well-defined, coherent magnetizations in the plutonic rocks may reflect the complex subsolidus alteration history of these rocks, as interpreted with Rb-Sr isotopic data. Hematitic sandstones of the earliest Ordovician Bliss Formation, which directly overlie the crystalline rocks in portions of the range, give dual-polarity magnetizations whose directions suggest that these rocks have probably been remagnetized; this remagnetization possibly occurred during deformation in late Cretaceous/Tertiary time. Ordovician carbonate rocks of the El Paso and Montoya formations give only a Holocene magnetization. Paleocene to earliest Eocene(?) hematite

  19. Geological Carbon Sequestration Storage Resource Estimates for the Ordovician St. Peter Sandstone, Illinois and Michigan Basins, USA

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, David; Ellett, Kevin; Leetaru, Hannes

    2014-09-30

    The Cambro-Ordovician strata of the Midwest of the United States is a primary target for potential geological storage of CO2 in deep saline formations. The objective of this project is to develop a comprehensive evaluation of the Cambro-Ordovician strata in the Illinois and Michigan Basins above the basal Mount Simon Sandstone since the Mount Simon is the subject of other investigations including a demonstration-scale injection at the Illinois Basin Decatur Project. The primary reservoir targets investigated in this study are the middle Ordovician St Peter Sandstone and the late Cambrian to early Ordovician Knox Group carbonates. The topic of this report is a regional-scale evaluation of the geologic storage resource potential of the St Peter Sandstone in both the Illinois and Michigan Basins. Multiple deterministic-based approaches were used in conjunction with the probabilistic-based storage efficiency factors published in the DOE methodology to estimate the carbon storage resource of the formation. Extensive data sets of core analyses and wireline logs were compiled to develop the necessary inputs for volumetric calculations. Results demonstrate how the range in uncertainty of storage resource estimates varies as a function of data availability and quality, and the underlying assumptions used in the different approaches. In the simplest approach, storage resource estimates were calculated from mapping the gross thickness of the formation and applying a single estimate of the effective mean porosity of the formation. Results from this approach led to storage resource estimates ranging from 3.3 to 35.1 Gt in the Michigan Basin, and 1.0 to 11.0 Gt in the Illinois Basin at the P10 and P90 probability level, respectively. The second approach involved consideration of the diagenetic history of the formation throughout the two basins and used depth-dependent functions of porosity to derive a more realistic spatially variable model of porosity rather than applying a

  20. Biodiversity, biogeography and phylogeography of Ordovician rhynchonelliform brachiopods

    DEFF Research Database (Denmark)

    Harper, David A. T.; Mac Ørum Rasmussen, Christian; Liljeroth, Maria

    2013-01-01

    -levels were high. Pivotal to the entire diversification is the role of gamma (inter-provincial) diversity and by implication the spread of the continents and frequency of island arcs and microcontinents. The phylogeographical analysis demonstrates that this new palaeogeographical configuration...... with local biodiversity epicentres, notably on the South China Palaeoplate; low-latitude porambonitoid-dominated faunas with early plectambonitoid and clitambonitoid representatives, as well as high-latitude assemblages mostly dominated by orthoids, can be recognized, but many taxa are rooted in Late......The phylogeographical evolution and the consequent changing distribution and diversity of rhynchonelliform brachiopods through the Ordovician are linked to the dynamic palaeogeography of the period. The Early Ordovician (Tremadocian and Floian) is characterized by globally low-diversity faunas...

  1. 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.

  2. Cambrian and ordovician systems around the pacific basin (part 3)

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Teiichi

    1987-10-25

    This report describes the history of the studies made about old rocks and Cambrian and Ordovician Systems in North America. In last century, development of the Pre-Canbrian stratigraphy and mineral resources was started in Canada, while the New York System was instituted in the middle and east areas of North America, and it was later correlated to the European sequence. Walcott who published many reports including the vental anatomy of trilobites made invaluable contribution on the study of Cambrian geology. The Cambro-Ordovician faunas which distributed in the Appalachian mountains and further westerly beyond the lower Mississipy river were related to the European ones. The systems in the Cordilleran geosyncline was also described. Stratigraphy in the western sites is followed on the Alaskan faunas in the north which were allied to the Siberian faunas and later to the Eastern Asiatic ones. Lastly, Circum-Pacific Cambro-Ordovician belt was taken up. The eastern side of the Circum-Pacific Cambrian belt belonged to Olenellian province, and the other side constituted the Redlichia province. (2 figs, 5 tabs, 101 refs)

  3. Ordovician ash geochemistry and the establishment of land plants.

    Science.gov (United States)

    Parnell, John; Foster, Sorcha

    2012-08-28

    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.

  4. The Strata-1 experiment on small body regolith segregation

    Science.gov (United States)

    Fries, Marc; Abell, Paul; Brisset, Julie; Britt, Daniel; Colwell, Joshua; Dove, Adrienne; Durda, Dan; Graham, Lee; Hartzell, Christine; Hrovat, Kenneth; John, Kristen; Karrer, Dakotah; Leonard, Matthew; Love, Stanley; Morgan, Joseph; Poppin, Jayme; Rodriguez, Vincent; Sánchez-Lana, Paul; Scheeres, Dan; Whizin, Akbar

    2018-01-01

    The Strata-1 experiment studies the mixing and segregation dynamics of regolith on small bodies by exposing a suite of regolith simulants to the microgravity environment aboard the International Space Station (ISS) for one year. This will improve our understanding of regolith dynamics and properties on small asteroids, and may assist in interpreting analyses of samples from missions to small bodies such as OSIRIS-REx, Hayabusa-1 and -2, and future missions to small bodies. The Strata-1 experiment consists of four evacuated tubes partially filled with regolith simulants. The simulants are chosen to represent models of regolith covering a range of complexity and tailored to inform and improve computational studies. The four tubes are regularly imaged while moving in response to the ambient vibrational environment using dedicated cameras. The imagery is then downlinked to the Strata-1 science team about every two months. Analyses performed on the imagery includes evaluating the extent of the segregation of Strata-1 samples and comparing the observations to computational models. After Strata-1's return to Earth, x-ray tomography and optical microscopy will be used to study the post-flight simulant distribution. Strata-1 is also a pathfinder for the new "1E" ISS payload class, which is intended to simplify and accelerate emplacement of experiments on board ISS.

  5. Ordovician of the Sauk megasequence in the Ozark region of northern Arkansas and parts of Missouri and adjacent states: Chapter 11

    Science.gov (United States)

    Ethington, Raymond L.; Repetski, John E.; Derby, James R.

    2012-01-01

    Exposures of Ordovician rocks of the Sauk megasequence in Missouri and northern Arkansas comprise Ibexian and lower Whiterockian carbonates with interspersed sandstones. Subjacent Cambrian strata are exposed in Missouri but confined to the subsurface in Arkansas. The Sauk-Tippecanoe boundary in this region is at the base of the St. Peter Sandstone. Ulrich and associates divided the Arkansas section into formations early in the 20th century, principally based on sparse collections of fossil invertebrates. In contrast, the distribution of invertebrate faunas and modern studies of conodonts will be emphasized throughout this chapter. Early workers considered many of the stratigraphic units to be separated by unconformities, but modern analysis calls into question the unconformable nature of some of their boundaries. The physical similarity of the several dolomites and sandstones, complex facies relations, and lack of continuous exposures make identification of individual formations difficult in isolated outcrops.

  6. Life on the edge in eastern Alaska: Basal Ordovician(Tremadocian), platform-margin faunas of the Jones Ridge Formation

    Science.gov (United States)

    Taylor, J. F.; Allen, T. J.; Repetski, John E.; Strauss, J. V.; Irwin, S. J.

    2015-01-01

    As the most fossiliferous and least deformed succession of unequivocally Laurentian lower Paleozoic strata in Alaska, the Jones Ridge Limestone has provided critical data for numerous stratigraphic studies (e. g. Palmer 1968; Harris et al. 1995; Dumoulin et al. 2002; Dumoulin and Harris 2012) focused on the Cambrian and Ordovician of northwestern North America/northeastern Laurentia (Figure 1). The Jones Ridge faunas are also significant in having provided the type material for some of the widespread and biostratigraphically useful latest Furongian and (perhaps) earliest Tremadocian species described by Kobayashi (1936) and Palmer (1968). Unfortunately, some of those taxa were based on very limited material for which, in the earlier study in particular, no detailed information regarding locality or stratigraphic horizon was provided. The limited amount of information and material available for study from Jones Ridge results largely from its remote location on the Yukon-Alaska boundary approximately 25km north of Eagle, Alaska, which renders it accessible only by helicopter. Parts of three field seasons (2010, 2011, and 2014) were invested in re-description and intensive sampling of the type section of the Jones Ridge Formation in order to produce an integrated and greatly refined set of biostratigraphic, chemostratigraphic, and sedimentological data. The new data support the interpretation offered by Palmer (1968) of the Jones Ridge strata as the product of deposition in outermost platform to upper slope environments offered by Palmer (1968) on the basis of taxonomic content of the faunas and close proximity of deep water units of equivalent age a very short distance to the southwest.

  7. 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.

  8. 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.

  9. A proposed global stratotype for the second series of the Ordovician system: Cow Head Peninsula, western Newfoundland

    Energy Technology Data Exchange (ETDEWEB)

    Williams, S.H. (Memorial Univ. of Newfoundland, St. John' s, NF (Canada)); Barnes, C.R. (Victoria Univ., BC (Canada)); Boyce, W.D. (Newfoundland Dept. of Mines and Energy, St. John' s, NF (Canada)); O' Brien, F.H.C

    1994-06-01

    The first occurrence of Tetragraptus approximatus approximatus is now taken to mark the base of the second (Arenig) series of the Ordovician System. It is proposed that the Cow Head Peninsula, western Newfoundland, be adopted for Global Stratotype Section and Point (GSSP), with the boundary placed at the base of the T. approximatus Zone, 2.9 m above the base of the Factory Cove Member, Shallow Bay Formation of the Cow Head Group. The well-preserved graptolite fauna occurs in association with abundant conodonts, demonstrating this level to correspond closely with the base of the Prionodus elegans conodont Zone. Immediately underlying strata yield bithecate graptoloid assemblages, generally taken as indicating the latest part of the previous (Tremadoc) series. Neighbouring sections also yield typically Tremadoc deep-water trilobites from this level, permitting correlation between the three fossil groups. Other fossils including acritarchs, are also present in the Cow Head sections, which are structurally simple, of low thermal maturity (CAI 1.5 or less) and suitable for chemo- and magnetostratigraphic studies. 80 refs., 8 figs.

  10. Ordovician A-type granitoid magmatism on the Ceará Central Domain, Borborema Province, NE-Brazil

    Science.gov (United States)

    Castro, Neivaldo A.; Ganade de Araujo, Carlos E.; Basei, Miguel A. S.; Osako, Liliane S.; Nutman, Alan A.; Liu, Dunyi

    2012-07-01

    We present field relationships, major and trace element geochemistry and U-Pb SHRIMP and ID-TIMS geochronology of the A-type Ordovician Quintas pluton located in the Ceará Central Domain of the Borborema Province, in northeastern Brazil. This pluton presents a concentric geometry and is composed mainly of syenogranite, monzogranite, quartz syenite to quartz monzodiorite, monzogabbro and diorite. Its geochemical characteristics [SiO2 (52-70%), Na2O/K2O (1.55-0.65), Fe2O3/MgO (2.2-7.3), metaluminous to sligthly alkaline affinity, post-collisional type in (Y + Nb) × Rb diagram, and A-type affinity (Ga > 22 ppm, Nb > 20 ppm, Zn > 60 ppm), REE fractioned pattern with negative Eu anomaly] are coherent with post-collisional A2-type granitoids. However, the emplacement of this pluton is to some extent temporally associated with the deposition of the first strata of the Parnaíba intracratonic basin, attesting also to a purely anorogenic character (A1-type granitoid). The emplacement of this pluton is preceded by one of the largest known orogenesis of the planet (Neoproterozoic Pan-African/Brasiliano) and, if it is classified as an A2-type granitoid, it provides interesting constraints about how long can last A2-type magmatic activity after a major collisional episode, arguably triggered by disturbance of the underlying mantle, a topic extensively debated in the geoscience community.

  11. Short-term dynamics of second-growth mixed mesophytic forest strata in West Virginia

    Science.gov (United States)

    Cynthia C. Huebner; Steven L. Stephenson; Harold S. Adams; Gary W. Miller

    2007-01-01

    The short-term dynamics of mixed mesophytic forest strata in West Virginia were examined using similarity analysis and linear correlation of shared ordination space. The overstory tree, understory tree, shrub/vine, and herb strata were stable over a six year interval, whereas the tree seedling and sapling strata were unstable. All strata but the shrub/vine and tree...

  12. 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.

  13. Supercritical strata in Lower Paleozoic fluvial rocks: a super critical link to upper flow regime processes and preservation in nature

    Science.gov (United States)

    Lowe, David; Arnott, Bill

    2015-04-01

    Recent experimental work has much improved our understanding of the lithological attributes of open-channel supercritical flow deposits, namely those formed by antidunes, chutes-and-pools and cyclic steps. However their limited documentation in the ancient sedimentary record brings into question details about their geological preservation. Antidune, chute-and-pool and cyclic step deposits are well developed in sandy ephemeral fluvial deposits of the Upper Cambrian - Lower Ordovician Potsdam Group in the Ottawa Embayment of eastern North America. These high energy fluvial strata form dm- to a few m-thick units intercalated within thick, areally expansive successions of sheet sandstones consisting mostly of wind ripple and adhesion stratification with common deflation lags. Collectively these strata record deposition in a semi-arid environment in which rare, episodic high-energy fluvial events accounted for most of the influx of sediment from upland sources. Following deposition, however, extensive aeolian processes reworked the sediment pile, and hence modified profoundly the preserved stratigraphic record. Antidune deposits occur as 0.2 - 1.6 m thick cosets made up of 2 - 15 cm thick lenticular sets of low angle (≤ 20o) cross-stratified, medium- to coarse-grained sandstone bounded by low-angle (5 - 15o) concave-upward scours and, in many cases, capped by low angle (10 - 15o) convex-upwards symmetrical formsets. Chute-and-pool deposits form single sets, 5 - 55 cm thick and 0.6 - 6 m wide, with scoured bases and low to high angle (5 - 25o) sigmoidal cross-strata consisting of medium- to coarse-grained sandstone. Cyclic step deposits consist of trough cross-stratified sets, 20 cm - 1.6 m thick, 2.5 - 12 m long and 7 - 35 m wide, typically forming trains that laterally are erosively juxtaposed at regularly-spaced intervals. They are composed of medium- to coarse-grained sandstone with concave-up, moderate to high angle (15 - 35o) cross-strata with tangential bases

  14. The evolutionary strata of DARPP-32 tail implicates hierarchical ...

    Indian Academy of Sciences (India)

    Predicted phosphorylation sites on DARPP-32 show conservation across vertebrates. Phylogenetics analysis indicates evolutionary strata of phosphorylation site acquisition at the C-terminus, suggesting functional expansion of DARPP-32, where more diverse signalling cues may involve in regulating DARPP-32 in ...

  15. The evolutionary strata of DARPP-32 tail implicates hierarchical ...

    Indian Academy of Sciences (India)

    The evolutionary strata of DARPP-32 tail implicates hierarchical functional expansion in higher vertebrates. CHOONG YONG UNG and TEOW CHONG TEOH. Supplementary data 1. Protein sequences of PPP1R1 family from 39 vertebrate species in FASTA format. Supplementary data 2. Multiple sequence alignment results ...

  16. Evidence of basement controlled faulting of cretaceous strata in the ...

    African Journals Online (AJOL)

    Evidence of basement controlled faulting of cretaceous strata in the Middle Benue Trough, Nigeria from lineament analysis of gravity data. ... anomaly map of part of the Middle Benue Trough, Nigeria, was used to investigate the genetic relationship between the basement and intra-sedimentary structures in the study area.

  17. The Palaeozoic strata near Moeche in Galicia, NW Spain

    NARCIS (Netherlands)

    Meer Mohr, van der C.G.

    1976-01-01

    Coral fragments, crinoidal debris and foraminifers found in limestone beds near Moeche (Galicia) are evidence of a Devonian-Silurian age for the strata in the greenschist facies belt around Cabo Ortegal, hitherto considered on the Spanish 1:200,000 map-La Coruña Hoja 1 (IGME), to be Precambrian in

  18. Late Ordovician (Ashgillian) glacial deposits in southern Jordan

    Science.gov (United States)

    Turner, Brian R.; Makhlouf, Issa M.; Armstrong, Howard A.

    2005-11-01

    The Late Ordovician (Ashgillian) glacial deposits in southern Jordan, comprise a lower and upper glacially incised palaeovalley system, occupying reactivated basement and Pan-African fault-controlled depressions. The lower palaeovalley, incised into shoreface sandstones of the pre-glacial Tubeiliyat Formation, is filled with thin glaciofluvial sandstones at the base, overlain by up to 50 m of shoreface sandstone. A prominent glaciated surface near the top of this palaeovalley-fill contains intersecting glacial striations aligned E-W and NW-SE. The upper palaeovalley-fill comprises glaciofluvial and marine sandstones, incised into the lower palaeovalley or, where this is absent, into the Tubeiliyat Formation. Southern Jordan lay close to the margin of a Late Ordovician terrestrial ice sheet in Northwest Saudi Arabia, characterised by two major ice advances. These are correlated with the lower and upper palaeovalleys in southern Jordan, interrupted by two subsidiary glacial advances during late stage filling of the lower palaeovalley when ice advanced from the west and northwest. Thus, four ice advances are now recorded from the Late Ordovician glacial record of southern Jordan. Disturbed and deformed green sandstones beneath the upper palaeovalley-fill in the Jebel Ammar area, are confined to the margins of the Hutayya graben, and have been interpreted as structureless glacial loessite or glacial rock flour. Petrographic and textural analyses of the deformed sandstones, their mapped lateral transition into undeformed Tubeiliyat marine sandstones away from the fault zone, and the presence of similar sedimentary structures to those in the pre-glacial marine Tubeiliyat Formation suggest that they are a locally deformed facies equivalent of the Tubeiliyat, not part of the younger glacial deposits. Deformation is attributed to glacially induced crustal stresses and seismic reactivation of pre-existing faults, previously weakened by epeirogenesis, triggering sediment

  19. High-resolution Chemostratigraphy Through a Nearshore, Mixed Carbonate-shale Succession of Late Ordovician Age (Sandbian-Katian) in the Laurentian Cratonic Interior

    Science.gov (United States)

    Anderson, N. T.; Steenberg, J.; Walters, A.; Retzler, A.; Frahm, E.; Feinberg, J. M.; Dworkin, S. I.; Cowan, C. A.; Runkel, A.

    2015-12-01

    High-resolution (20cm sampling interval) δ13Ccarb, δ13Corg, and pXRF data from core and outcrop exposures of a mixed carbonate-shale succession of Late Ordovician age (Sandbian-Katian) provide insight into the nearshore paleoceanography of Laurentian epeiric seas during a time of global marine perturbations. These strata occur along a 250km transect in Minnesota and Iowa. They represent deposition in a tectonically stable, marginal marine setting that records the interplay of (1) seafloor topography, (2) sea level change, (3) terrigenous influx that periodically smothered a benthic heterozoan faunal community, and (4) production of micritic carbonate that eludes assignment to obvious depositional conditions. Preliminary analyses of δ13Ccarb data from closely spaced sections of the Platteville Formation reveal km-scale lateral variation in the isotopic record. Amid current debate over the interpretation of isotopically distinct "aquafacies" in epeiric seas (reported in these and similar strata elsewhere), our data appear to distinguish regional lithofacies and allow correlation through an otherwise sedimentologically-opaque carbonate rock. Comparison of δ13Ccarb with δ13Corg from carbonate and shale units through the Platteville, Decorah and Cummingsville Formations permits time correlation across significant facies and paleoceanographic gradients in the study area. High-resolution lithostratigraphic data from pXRF allows comparison with this isotopic chronostratigraphy. This time interval includes cooling at the onset of global ice-house conditions (under relatively elevated atmospheric CO2 levels), perturbations of the carbon cycle evinced by δ13C excursions (e.g., GICE) and unusual marine ashfalls preserved as well known K-bentonites in the study area (Millbrig, Deicke, etc.). These strata provide an opportunity to study the dynamics of the most inshore and possibly most sensitive setting preserved for this system.

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

    DEFF Research Database (Denmark)

    Frisk, Åsa M.; Harper, David Alexander Taylor

    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........ Moreover the development of new community types and narrowly-defined niches helped further drive both a and p biodiversity during a critical phase of the Great Ordovician Biodiversification Event (C) 2012 Elsevier B.V. All rights reserved....

  1. SHORT COMMUNICATION: First record of the trace fossil Oikobesalon from the Ordovician (Darriwilian of Baltica

    Directory of Open Access Journals (Sweden)

    Olev Vinn

    2014-05-01

    Full Text Available The ichnogenus Oikobesalon is here described from the Ordovician of Baltica for the first time. All the specimens in this study were found on Osmussaar Island, Estonia. They belong to the ichnospecies Oikobesalon coricaceum. In the Cambrian and Ordovician, Oikobesalon seems to have occurred only in cold to temperate seas. The Oikobesalon trace-maker presumably used its burrow permanently for dwelling and searched for its food through the burrow aperture that likely opened to the sediment–water interface.

  2. Law of Strata Pressure Behavior in Shallow Coal Seam

    Science.gov (United States)

    Zhao, Jian; Liu, Leibin; Zheng, Zhiyang

    2018-02-01

    The law of strata pressure behavior in shallow coal seam is analyzed, according to the load data of Jinjie Coal Mine 31109 working face hydraulic supports. The first weighting distance of main roof is 80 m, and the periodic weighting distance of main roof is about 20 m. And according to the load data in the middle and both ends of the working face, the working resistance of hydraulic supports and the setting load are a bit small, so they couldn’t meet the needs of supporting roof. Then, the front abutment pressure of working face is analyzed by numerical simulation. It does not only explain the reason that the load is too big, but also explains the reason that the strata pressure behavior in shallow coal seam is serious. The length of undamaged main roof rock beam verifies the correctness of the periodic weighting distance.

  3. Oxygen and carbon isotope composition of Gordon Group carbonates (Ordovician), Florentine Valley, Tasmania, Australia

    International Nuclear Information System (INIS)

    Rao, C.P.; Wang, B.

    1990-01-01

    The Gordon Group carbonates consist of biota of the Chlorozoan assemblage, diverse non-skeletal grains and abundant micrite and dolomite, similar to those of modern warm water carbonates. Cathodoluminescence studies indicate marine, meteoric and some burial cements. Dolomites replacing burrows, mudcracks and micrite formed during early diagenesis. δ 18 O values of the non-luminescent fauna and marine cement are lighter than those of modern counterparts but are similar to those existing within low latitudes during the Ordovician because of the light δ 18 O values of Ordovician seawater. The δ 18 O difference between marine and meteoric calcite indicate that during the Early Ordovician there were high atmospheric CO 2 levels than at present but during the Middle and Late Ordovician they became comparable with the present because of a change from 'Greenhouse' to glacial conditions. δ 18 O values of Late Ordovician seawater were heavier than in the Middle Ordovician mainly because of glaciation. It is thus concluded that dolomitization took place in marine to mixed-marine waters while the original calcium carbonate was undergoing marine to meteoric diagenesis. 41 refs., 1 tab., 9 figs

  4. Variability in Abundances of Meteorites in the Ordovician

    Science.gov (United States)

    Heck, P. R.; Schmitz, B.; Kita, N.

    2017-12-01

    The knowledge of the flux of extraterrestrial material throughout Earth's history is of great interest to reconstruct the collisional evolution of the asteroid belt. Here, we present a review of our investigations of the nature of the meteorite flux to Earth in the Ordovician, one of the best-studied time periods for extraterrestrial matter in the geological record [1]. We base our studies on compositions of extraterrestrial chromite and chrome-spinel extracted by acid dissolution from condensed marine limestone from Sweden and Russia [1-3]. By analyzing major and minor elements with EDS and WDS, and three oxygen isotopes with SIMS we classify the recovered meteoritic materials. Today, the L and H chondrites dominate the meteorite and coarse micrometeorite flux. Together with the rarer LL chondrites they have a type abundance of 80%. In the Ordovician it was very different: starting from 466 Ma ago 99% of the flux was comprised of L chondrites [2]. This was a result of the collisional breakup of the parent asteroid. This event occurred close to an orbital resonance in the asteroid belt and showered Earth with >100x more L chondritic material than today during more than 1 Ma. Although the flux is much lower at present, L chondrites are still the dominant type of meteorites that fall today. Before the asteroid breakup event 467 Ma ago the three groups of ordinary chondrites had about similar abundances. Surprisingly, they were possibly surpassed in abundance by achondrites, materials from partially and fully differentiated asteroids [3]. These achondrites include HED meteorites, which are presumably fragments released during the formation of the Rheasilvia impact structure 1 Ga ago on asteroid 4 Vesta. The enhanced abundance of LL chondrites is possibly a result of the Flora asteroid family forming event at 1 Ga ago. The higher abundance of primitive achondrites was likely due to smaller asteroid family forming events that have not been identified yet but that did

  5. Characteristics of depositional sequences, systems tracts and bounding surfaces in Early Ordovician greenhouse passive margin carbonates to Late Ordovician glacio-eustatic influenced foreland basin facies

    Energy Technology Data Exchange (ETDEWEB)

    Pope, M.C.; Read, J.F. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Geology)

    1994-03-01

    Passive margin, cyclic carbonates of the Early Ordovician Knox Group, Appalachians are dominated by meter scale dolomitized carbonate cycles. These are stacked into 1 to 5 m.y. depositional sequences that appear to be relatively conformable. The sequences are defined by stacking patterns on Fischer plots that graph long term changes in accommodation with thick less dolomitized cycles in the TST, and thin, highly dolomitized cycles in the HST, becoming quartzose in the late HST and LST. Sequence and systems tract boundaries are subtle and typically marked by zones of cycles rather than single discrete surfaces. In contrast, sequences in the later Ordovician foreland basin fill locally show: (1) sequence bounding unconformities on the Knox, the Camp Nelson and on top of the Ordovician, (2) well defined low stand deposits as in the subaerial breccias and detrital dolomite muds veneering the Knox unconformity; redbeds and associated quartz sands and conglomerates with intercalated peritidal carbonate layers and their distal equivalent peritidal laminites; (3) TST's in the lower part of the Middle Ordovician limestones include regionally traceable cyclic peritidal carbonates or in the lower Lexington Limestone, transgressive high energy grainstones; (4) HST's consist of poorly cyclic deeper water up into shallow water grainstone bank and northward prograding peritidal carbonate facies; The ongoing study of detailed logs of outcrop and core should help refine the understanding of the fine scale makeup of sequences developed in these contrasting tectonic and global climatic settings.

  6. Consumption Behavior of Middle Strata in Times of Economic Crisis

    Directory of Open Access Journals (Sweden)

    Svetlana V. Mareeva

    2017-03-01

    Full Text Available Based on the data of national representative surveys carried out by IS RAS in 2014-2016, the author presents analysis of consumption specifics in middle-income groups in times of current economic crisis. It is shown that although in modern Russian society middle income groups make up the majority of population, they cannot be directly correlated with the middle class defined in class theory framework. Middle-income groups are heterogeneous in different aspects, including their consumption specifics. Their standard of living remains quite modest, although it is significantly higher than the “survival standard”. New economic conditions led to widespread economy practices among them - primarily on consumption, followed by economy on hobbies and vacations. Economy practices also seriously affected middle-income strata investments in human capital – usage of paid educational and health services (this type of economy was more widespread among lower middle-income group than higher. Although representatives of the middle-income strata are quite actively using paid medical services (and relatively rarely – paid educational services, the reason for this more often lies in inaccessibility of free analogues rather than in search for the higher quality. Process of durables renewal in middle strata during the crisis was not as active, but their standard set of durable goods still widened over the past two years - primarily due to the relatively complex technological durables that they are gradually transferred from the category of innovation goods to the extended standard. In this regard, the upper middle income group successfully performs the function of the innovative consumer.

  7. Tectonic obliteration of magmatic fabrics in an Ordovician ophiolite

    Science.gov (United States)

    Di Chiara, A.; Morris, A.; Anderson, M. W.; Menegon, L. M.

    2017-12-01

    The Thetford Mines Ophiolite (TMO) is part of the Canadian Appalachians (Quebec region) which experienced syn-emplacement and two post-emplacement deformations, the Taconian (Ordovician) and the (Devonian) Acadian orogenies. New results from an integrated rock magnetic, petrological and microstructural study on 12 paleomagnetic sites show a complete tectonic overprint of the original magnetic fabric. Anisotropy of magnetic susceptibility (AMS) results show that on the southern layered gabbros the magnetic fabric is locally preserved, being parallel to observed magmatic foliations. The nine sites from the northwestern sector of the TMO share a remarkably similar magnetic fabric, despite formed by fundamentally different magmatic processes. They are all characterized by a minimum anisotropy axis (kmin) oriented NW-SE and the maximum axis (kmax) steeply plunging to the NE. Additional microstructural analyses show that the kmax of the magnetic fabric is subparallel to the crystal preferred orientation of the iron rich particles. We think that at low strain regime the AMS fabric reflect the magmatic foliation; whereas at higher strain regime the AMS fabric has a tectonic overprint consistent with a shortening direction perpendicular to the regional trend of fold axes, thus recording the last regional tectonic event during the Acadian orogeny.

  8. The Strata-l Experiment on Microgravity Regolith Segregation

    Science.gov (United States)

    Fries, M.; Abell, P.; Brisset, J.; Britt, D.; Colwell, J.; Durda, D.; Dove, A.; Graham, L.; Hartzell, C.; John, K.; hide

    2016-01-01

    The Strata-1 experiment studies the segregation of small-body regolith through long-duration exposure of simulant materials to the microgravity environment on the International Space Station (ISS). Many asteroids feature low bulk densities, which implies high values of porosity and a mechanical structure composed of loosely bound particles, (i.e. the "rubble pile" model), a prime example of a granular medium. Even the higher-density, mechanically coherent asteroids feature a significant surface layer of loose regolith. These bodies will evolve in response to very small perturbations such as micrometeoroid impacts, planetary flybys, and the YORP effect. A detailed understanding of asteroid mechanical evolution is needed in order to predict the surface characteristics of as-of-yet unvisited bodies, to understand the larger context of samples from sample return missions, and to mitigate risks for both manned and unmanned missions to asteroidal bodies. Due to observation of rocky regions on asteorids such as Eros and Itokawa, it has been hypothesized that grain size distribution with depth on an asteroid may be inhomogeneous: specifically, that large boulders have been mobilized to the surface. In terrestrial environments, this size-dependent sorting to the surface of the sample is called the Brazil Nut Effect. The microgravity and acceleration environment on the ISS is similar that of a small asteroid. Thus, Strata-1 investigates size segregation of regolith in an environment analogous to that of small bodies. Strata-1 consists of four regolith simulants in evacuated tubes, as shown in Figure 1 (Top and Middle). The simulants are (1) a crushed and sieved ordinary chondrite meteorite to simulate an asteroidal surface, (2) a carbonaceous chondrite simulant with a mixture of fine and course particles, and two simplified silicate glass simulants; (3) one with angular and (4) another with spherical particles. These materials were chosen to span a range of granular

  9. Mechanisms of Mining Seismicity under Large Scale Exploitation with Multikey Strata

    Directory of Open Access Journals (Sweden)

    Hu He

    2015-01-01

    Full Text Available The dynamic disasters are aggravating with the increase of exploitation scale and intensity in Chinese coal mines, to further understand this problem, we studied the mechanisms of mining tremors induced by key strata movement and instability under large scale exploitation. First the mechanisms were categorized into two groups that is main key strata fracture and movement as well as subkey strata instability again under adjacent mining activities. Based on the key strata theory in ground control we revealed three basic mechanisms of key strata destabilization that are rotary and sliding of low subkey strata, shear sliding of the high subkey strata, and the main key strata rupture and cave at limit span, respectively. The microseismic observing systems were applied to monitor the mining tremor events and verify the theoretical analysis in different coal mines. The characteristics of time-space evolution of tremors show that low inferior key strata causing the most, followed by the high inferior key strata and the main key strata least, however the released energy was just opposite.

  10. Mercury spikes suggest volcanic driver of the Ordovician-Silurian mass extinction.

    Science.gov (United States)

    Gong, Qing; Wang, Xiangdong; Zhao, Laishi; Grasby, Stephen E; Chen, Zhong-Qiang; Zhang, Lei; Li, Yang; Cao, Ling; Li, Zhihong

    2017-07-13

    The second largest Phanerozoic mass extinction occurred at the Ordovician-Silurian (O-S) boundary. However, unlike the other major mass extinction events, the driver for the O-S extinction remains uncertain. The abundance of mercury (Hg) and total organic carbon (TOC) of Ordovician and early Silurian marine sediments were analyzed from four sections (Huanghuachang, Chenjiahe, Wangjiawan and Dingjiapo) in the Yichang area, South China, as a test for evidence of massive volcanism associated with the O-S event. Our results indicate the Hg concentrations generally vary in parallel with TOC, and that the Hg/TOC ratios remain low and steady state through the Early and Middle Ordovician. However, Hg concentrations and the Hg/TOC ratio increased rapidly in the Late Katian, and have a second peak during the Late Hirnantian (Late Ordovician) that was temporally coincident with two main pulses of mass extinction. Hg isotope data display little to no variation associated with the Hg spikes during the extinction intervals, indicating that the observed Hg spikes are from a volcanic source. These results suggest intense volcanism occurred during the Late Ordovician, and as in other Phanerozoic extinctions, likely played an important role in the O-S event.

  11. Prehistory of Zodiac Dating: Three Strata of Upper Paleolithic Constellations

    Science.gov (United States)

    Gurshtein, Alex A.

    A pattern of archaic proto-constellations is extracted from Aratus' "The Phaenomena" didactic poem list according to a size criterion elaborated earlier, and their symbolism is analyzed. As a result of this approach three celestial symbolical strata are discovered to be probably a reflection of the symbols for the Lower, the Middle and the Upper Worlds; the Under-World creatures have a water character, the Middle World ones are mostly anthropomorphic and flying beings are for the Upper World. The strata excerpted from Aratus' sky seems to be in agreement with the well-known Babylonian division into three god pathways for Ea (Enki), Anu and Enlil. There is a possibility of dating the pattern discovered because of precession's strong influence as far back as 16 thousand years, the result being supported by the comparison of different star group mean sizes. The archaic constellation pattern under consideration is a reasonable background of symbolical meanings for the first Zodiacal generation quartet (7.5 thousand years old) examined by the author previously. The enormous size of the Argo constellation (Ship of Argo and his Argonauts) as well as the large sizes of other southern constellations are explained as due to the existence of an accumulation zone near the South celestial pole. Some extra correlations between the reconstruction proposed and cultural data available are discussed. The paper is the second part of the investigation "On the Origin of the Zodiacal constellations" published in Vistas in Astronomy, vol.36, pp.171-190, 1993.

  12. Stratigraphic significance of Cruziana: New data concerning the Cambrian-Ordovician ichnostratigraphic paradigm

    Energy Technology Data Exchange (ETDEWEB)

    Magwood, J.P.A.; Pemberton, S.G. (Univ. of Alberta, Edmonton (Canada))

    1990-08-01

    The classic Cambrian-Ordovician ichnostratigraphic paradigm originally developed in Europe is based on the assumption that Cruziana - ichnofossils presumably produced by trilobites - can be used in much the same way as trilobite body fossils have been used in chronostratigraphy. That these ichnofossils can be found in many otherwise unfossiliferous, shallow-marine siliciclastic deposits has made them extremely valuable as correlation tools. The paradigm has been used to date lower Paleozoic units in eastern Canada and Europe. It has also been used as supporting evidence to show close affinities between (1) eastern North America, Wales, and Spain and (2) Spain, northern Africa, and southern Asia. Ichnospecies indicative of the Lower Ordovician (Tremadocian and Arenigian), according to the paradigm, have been recovered from the Lower Cambrian (Atdabanian) Gog Group, near Lake Louise, Alberta, Canada. This discovery indicates that these ichnospecies cannot be used as global Lower Ordovician index fossils.

  13. El Paso Formation - a Lower Ordovician platform carbonate deposit

    Energy Technology Data Exchange (ETDEWEB)

    Clemons, R.E.

    1987-05-01

    The eastward-transgressive Lower Ordovician El Paso Formation conformably overlies Bliss Sandstone in southern New Mexico. Locally, lower El Paso was deposited on low hills of plutonic and volcanic rocks. The region subsided gradually throughout Canadian time, receiving the El Paso carbonate rock blanket up to 460 m thick. Lithologic and chronologic correlative rocks were deposited over most of the southwestern US as the first Paleozoic carbonate platform sequence. The El Paso Formation contains four members, listed here in ascending order: Hitt Canyon, Jose, McKelligon, and Padre. Gradually decreasing sand content upward through the Hitt Canyon indicates deepening water and/or greater distance to shore. Girvanella(.) oncolites are locally abundant. Stromatolite mounds near the top of the Hitt Canyon, combined with an influx of sand, ooids, and rounded bioclasts in the Jose Member, recorded a shoaling phase. The overlying McKelligon Member contains little or no sand, and sponge-Calathium mounds are prominent at some locales. Stromatolite mounds are interbedded with sponge-Calathium mounds in a few sections. Lower Padre Member beds are typically silty to sandy and locally contain thinly-laminated zones. The Padre contains more restricted fauna that includes traces of ostracods. Pervasive bioturbation of El Paso beds and fauna consisting of echinoderms, sponges, gastropods, trilobites, Nuia, Calathium, cephalopods, and algae plus minor brachiopods and Pulchrilamina indicate predominating shallow-subtidal environments. Low-energy platform environments, in which a large volume of micritic muds accumulated, were disturbed thousands of times by storms producing abundant thin, poorly washed biosparite, intrasparite, and intrasparrudite lenses.

  14. New agnostina (Trilobita from the Llanvirn (Ordovician of Spain

    Directory of Open Access Journals (Sweden)

    Rábano, I.

    1985-12-01

    Full Text Available The agnostids from the Lower Llanvirn shales of the Southern Central-Iberian Zone (Mounts of Toledo, Villuercas and Almadén district are described. Seven localities are new for Ordovician agnostids and two are revised. Three new species, belonging to the genera Geragnostella and Geragnostus, are described: Geragnostella gilcidae n. sp., Geragnostus hispanicus n. sp. and Geragnostus ninhursagae n. sp. The new names Geragnostus pilleti nom. nov. and Geragnostus abdullaevi nom. nov. are proposed to rename, respectively, the species G. howelli PILLET, 1978 and G. elongatus ABDULLAEV, 1972, regarded herein as junior objective homonyms of other previously defined species.

    Se estudian los trilobites agnóstidos procedentes de nueve localidades, siete de ellas nuevas para estas faunas, situadas en las pizarras del Llanvirn inferior de la parte meridional de la Zona Centroibérica (Montes de Toledo, Villuercas y región de Almadén. Se determina la presencia de los géneros Geragnostella y Geragnostus, y se describen tres nuevas especies: Geragnostella gilcidae n. sp., Geragnostus hispanicus n. sp. y Geragnostus ninhursagae n. sp. Se proponen también los nuevos nombres Geragnostus pilleti nom. nov. y Geragnostus abdullaevi nom. nov. para designar, respectivamente, las especies G. howelli PILLET, 1978, y G. elongatus ABDULLAEV, 1972, consideradas ambas homónimos objetivos primarios de otras especies definidas con anterioridad.

  15. 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

    of seawater is controlled by inputs from oxidative weathering on land and redox transformations in marine environments. Preliminary results indicate a major shift in d53Cr values from +0.5‰ to 0‰ across the Early to Middle Ordovician boundary, accompanied by an increase in Cr concentration from 0.1 to 0......-existing pyrite in the later Middle Ordovician are consistent with oxygen mixing at depth and ventilation of euxinic bottom waters [4]. We measured the Cr isotopic composition of an Early to Middle Ordovician carbonate platform to test whether Cr isotopes record ocean oxygenation. The Cr isotopic composition....... This hypothesized change in redox at the Early to Middle Ordovician boundary may preface more widespread ventilation in the later Middle Ordovician. [1] Hurtgen et al., 2009, EPSL v 281 p. 288-297 [2] Gill et al., 2011, GEOCHIM COSOCHIM AC v 72 p. 4699-4711 [3] Thompson and Kah, 2012 Palaeogeogr. Palaeoclimatol...

  16. Early Ordovician (Tremadocian brachiopods from the Eastern Alborz Mountains, Iran

    Directory of Open Access Journals (Sweden)

    Leonid E. Popov

    2011-06-01

    Full Text Available Six linguliform and two rhynchonelliform brachiopods, including three new species Eurytreta ahmadii, Wahwahlingula kharbashi and Nanorthis bastamensis are described from Tremadocian strata (Paltodus deltifer deltifer conodont Biozone in the Deh-Molla area southwest of Shahrud, Northern Iran. The fauna is dominated by micromorphic lingulides and acrotretides and shows distinct similarity to the contemporaneous micromorphic brachiopod association from Tremadocian chalcedonites of the Holy Cross Mountains, Poland. New data on the early ontogeny of the enigmatic lingulide Diencobolus show a very distinct pattern, including the presence of a metamorphic protegulum ornamented with flat-based pits and a single pair of larval setal bundles, which links this taxon to Paterula and suggests close phylogenetic relationships of both taxa to the Discinoidea.

  17. High potential for weathering and climate effects of non-vascular vegetation 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

    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

  18. Shales and other argillaceous strata in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, S.; Johnson, K.S.

    1985-03-01

    This report presents detailed geologic and hydrologic data that describe shales and other argillaceous rocks; data are from the open literature. These data are intended to be used in the future to aid in assessment of various strata and their potential for repository siting. No observations, conclusions, or recommendations are made by the authors of this report relative to the suitability of various argillaceous rocks for waste disposal. There are, however, other published reports that contain technical data and evaluative statements regarding the suitability of various argillaceous rocks for repository siting. Where appropriate, the authors of this report have referenced this previously published literature and have summarized the technical data. 838 refs., 121 figs., 6 tabs.

  19. Shales and other argillaceous strata in the United States

    International Nuclear Information System (INIS)

    Gonzales, S.; Johnson, K.S.

    1985-03-01

    This report presents detailed geologic and hydrologic data that describe shales and other argillaceous rocks; data are from the open literature. These data are intended to be used in the future to aid in assessment of various strata and their potential for repository siting. No observations, conclusions, or recommendations are made by the authors of this report relative to the suitability of various argillaceous rocks for waste disposal. There are, however, other published reports that contain technical data and evaluative statements regarding the suitability of various argillaceous rocks for repository siting. Where appropriate, the authors of this report have referenced this previously published literature and have summarized the technical data. 838 refs., 121 figs., 6 tabs

  20. Detrital zircon U-Pb and (U-Th)/He double-dating of Upper Cretaceous-Cenozoic Zagros foreland basin strata in the Kurdistan Region of northern Iraq

    Science.gov (United States)

    Barber, D. E.; Stockli, D. F.; Koshnaw, R. I.; Horton, B. K.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The NW Zagros orogen is the result of the multistage collisional history associated with Late Cretaceous-Cenozoic convergence of the Arabian and Eurasian continents and final closure of Neotethys. Siliciclastic strata preserved within a ~400 km segment of the NW Zagros fold-thrust belt and foreland basin in the Iraqi Kurdistan Region (IKR) provide a widespread record of exhumation and sedimentation. As a means of assessing NW Zagros foreland basin evolution and chronostratigraphy, we present coupled detrital zircon (DZ) U-Pb and (U-Th)/He geo-thermochronometric data of Upper Cretaceous to Pliocene siliciclastic strata from the Duhok, Erbil, and Suleimaniyah provinces of IKR. LA-ICP-MS U-Pb age analyses reveal that the foreland basin fill in IKR in general was dominantly derived from Pan-African/Arabian-Nubian, Peri-Gondwandan, Eurasian, and Cretaceous volcanic arc terrenes. However, the provenance of these strata varies systematically along strike and through time, with an overall increase in complexity upsection. DZ age distribution of Paleocene-Eocene strata is dominated by a ~95 Ma grain age population, likely sourced from the Late Cretaceous Hassanbag-Bitlis volcanic arc complex along the northern margin of Arabia. In contrast, DZ U-Pb age distributions of Neogene strata show a major contribution derived from various Eurasian (e.g., Iranian, Tauride, Pontide; ~45, 150, 300 Ma) and Pan-African (~550, 950 Ma) sources. The introduction of Eurasian DZ ages at the Paleogene-Neogene transition likely records the onset of Arabian-Eurasian collision. Along strike to the southeast, the DZ U-Pb spectra of Neogene strata show a decreased percentage of Pan-African, Peri-Gondwandan, Tauride, and Ordovician ages, coupled with a dramatic increase in 40-50 Ma DZ ages that correspond to Urumieh-Dokhtar magmatic rocks in Iran. Combined with paleocurrent data, this suggests that Neogene sediments were transported longitudinally southeastward through an unbroken foreland basin

  1. Behaviors of overlying strata in extra-thick coal seams using top-coal caving method

    Directory of Open Access Journals (Sweden)

    Bin Yu

    2016-04-01

    Full Text Available Accidents such as support failure and excessive deformation of roadways due to drastic changes in strata behaviors are frequently reported when mining the extra-thick coal seams Nos. 3–5 in Datong coal mine with top-coal caving method, which significantly hampers the mine's normal production. To understand the mechanism of strata failure, this paper presented a structure evolution model with respect to strata behaviors. Then the behaviors of strata overlying the extra-thick coal seams were studied with the combined method of theoretical analysis, physical simulation, and field measurement. The results show that the key strata, which are usually thick-hard strata, play an important role in overlying movement and may influence the mining-induced strata behaviors in the working face using top-coal caving method. The structural model of far-field key strata presents a “masonry beam” type structure when “horizontal O-X” breakage type happens. The rotational motion of the block imposed radial compressive stress on the surrounding rock mass of the roadway. This can induce excessive deformation of roadway near the goaf. Besides, this paper proposed a pre-control technology for the hard roof based on fracture holes and underground roof pre-splitting. It could effectively reduce stress concentration and release the accumulated energy of the strata, when mining underground coal resources with top-coal caving method.

  2. Possible extrinsic controls on the Ordovician radiation: Stratigraphic evidence from the Great Basin, western USA

    Energy Technology Data Exchange (ETDEWEB)

    Droser, M.L. (Univ. of California, Riverside, CA (United States). Dept. of Earth Sciences); Fortey, R.A. (Natural History Museum, London (United Kingdom). Dept. of Palaeontology)

    1993-04-01

    The Ordovician radiation has been previously examined by looking at 1/analyses of patterns of diversification within small clades, 2/analyses of large databases to elucidate large-scale paleoecological patterns such as increased tiering and onshore-offshore shifts associated with this radiation. In order to resolve the relationships between these two scales of analysis there is critical need to examine in detail the paleoecology and possible biofacies shifts associated with the Ordovician radiation. The authors have examined the base of the Whiterock Series (Lower-Middle Ordovician) in the Great Basin as it represents one of the most complete records of the Ordovician radiation on the North American continent. Detailed field evidence suggests that the base of the Whiterock does not represent a simple faunal turnover but corresponds with the first occurrences in the region of groups that come to dominate the rest of the Paleozoic. Among the trilobites, this includes the lichides, calymenids, proetides, and phacopides. Similar patterns are found among the dominate Paleozoic bivalve, cephalopod, brachiopod and graptolite clades. Global correlation of this time interval suggests that this pattern of first broad geographic occurrences is not unique to North America. This boundary corresponds with a globally recognized sea level lowstand. In the Great Basin, significant facies shifts are present in shallow and deep water settings. While extrinsic controls are commonly reserved for extinctions, these data suggest that extrinsic factors may have been significant in the timing of the Paleozoic fauna rose to dominance.

  3. Uppermost Ordovician (upper Katian-Hirnantian) graptolites of north-central Nevada, U.S.A

    Czech Academy of Sciences Publication Activity Database

    Štorch, Petr; Mitchell, Ch. E.; Finney, S. C.; Melchin, M. J.

    2011-01-01

    Roč. 86, č. 2 (2011), s. 301-386 ISSN 1214-1119 R&D Projects: GA AV ČR IAA301110908 Institutional research plan: CEZ:AV0Z30130516 Keywords : Ordovician * graptolites * mass extinction * biostratigraphy Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.099, year: 2011

  4. 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.

  5. 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.

  6. Groundwater quality in the Cambrian-Ordovician aquifer system, midwestern United States

    Science.gov (United States)

    Stackelberg, Paul E.

    2017-12-07

    Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water (Burow and Belitz, 2014). The Cambrian-Ordovician aquifer system constitutes one of the important areas being evaluated.

  7. Ichnological aspect of fossiliferous nodules of the Šárka Formation (Ordovician, llanvirnian, Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Mikuláš, Radek

    2003-01-01

    Roč. 78, č. 1 (2003), s. 13-18 ISSN 1210-3527 Grant - others:UNESCO(XX) IGCP:410 Institutional research plan: CEZ:AV0Z3013912 Keywords : Ordovician * Llanvirnian * ichnofossils Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/bulletin/contents/2003/vol78no1/08-mikulas.pdf

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

    DEFF Research Database (Denmark)

    Candela, Yves; Hansen, Thomas

    2010-01-01

    and their preferences in the late Middle Ordovician of the Oslo Region, southern Norway, than ever before. The brachiopod faunas are described in the present article, which include a new genus and a new species respectively Wandaasella modheimrensis and Cyclomyonia vikersundi. The brachiopod fauna is largely dominated...

  9. Resistivity imaging of strata and faults in Bangladesh

    Science.gov (United States)

    Hosain, A.; Steckler, M. S.; Akhter, S. H.

    2015-12-01

    The Ganges-Brahmaputra-Meghna Delta, the largest in the world, is subject to deformation by active tectonics and dynamic river systems. It lies near the juncture of the Indian, Eurasian and Burmese plates and is being overthrust by both the Shillong Massif and the Indo-Burman Ranges. There are multiple major and minor active faults in Bangladesh, many of which are buried by the sedimentation. For example, the Madhupur tract is a Pleistocene upland in the middle part of Bengal Basin. Whether it is a passive interfluve of the river system or a tilted and tectonically uplifted block has been debated for decades. The Tippera Surface, in Comilla at the eastern part of the basin, is composed of uplifted and oxidized Holocene strata and overlies buried anticlines of the Indo-Burman fold belt. Furthermore, the rivers are subject to migrations, avulsions and other changes in course. The last major avulsion of the Brahmaputra River was only ~200 years ago. During the sea level fall in the last glaciation the major rivers created large incised valleys. In much of the exposed uplands there was the development of a weathered clay surface. This now forms a clay layer separating the Pleistocene and Holocene strata in large parts of Bangladesh. We use electrical resistivity surveying and hand-drilled borehole lithological data to better understand the subsurface discontinuities and structures. The resistivity system consists of an 84 electrode array powered by 2 car batteries and is capable of imaging lithologies to ~100m depth, similar to the depths of the boreholes used to calibrate the data. We extend our previous work on the western margin of the Madhupur Tract with additional lines on the eastern flank of Madhupur. Resistivity lines along the exposed Lalmai anticline in Comilla image the now tilted Holocene-Pleistocene clay layer. Additional lines along the subsurface continuation of the anticline provide additional information on the subsurface lithologies associated with

  10. 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.

  11. Managed Multi-strata Tree + Crop Systems: An Agroecological Marvel

    Directory of Open Access Journals (Sweden)

    P. K. Ramachandran Nair

    2017-12-01

    Full Text Available Today, when the emphasis on single-species production systems that is cardinal to agricultural and forestry programs the world over has resulted in serious ecosystem imbalances, the virtues of the time-tested practice of growing different species together as in managed Multi-strata Tree + Crop (MTC systems deserve serious attention. The coconut-palm-based multispecies systems in tropical homegardens and shaded perennial systems are just two such systems. A fundamental ecological principle of these systems is niche complementarity, which implies that systems that are structurally and functionally more complex than crop- or tree monocultures result in greater efficiency of resource (nutrients, light, and water capture and utilization. Others include spatial and temporal heterogeneity, perennialism, and structural and functional diversity. Unexplored or under-exploited areas of benefits of MTC systems include their ecosystem services such as carbon storage, climate regulation, and biodiversity conservation. These multispecies integrated systems indeed represent an agroecological marvel, the principles of which could be utilized in the design of sustainable as well as productive agroecosystems. Environmental and ecological specificity of MTC systems, however, is a unique feature that restricts their comparison with other land-use systems and extrapolation of the management features used in one location to another.

  12. Identify and draft outcomes-based training material in strata control for underground workers.

    CSIR Research Space (South Africa)

    Johnson, RA

    2000-03-01

    Full Text Available Glossary of terms and definitions ....................................................... A-1 Appendix B Literature review................................................................................. B-1 Appendix C International training material... Literature review A literature review was conducted of prevailing strata control hazards in gold and platinum mines, local and international strata control training content and the methodology and terminology associated with outcomes-based training...

  13. Post-stratified estimation: with-in strata and total sample size recommendations

    Science.gov (United States)

    James A. Westfall; Paul L. Patterson; John W. Coulston

    2011-01-01

    Post-stratification is used to reduce the variance of estimates of the mean. Because the stratification is not fixed in advance, within-strata sample sizes can be quite small. The survey statistics literature provides some guidance on minimum within-strata sample sizes; however, the recommendations and justifications are inconsistent and apply broadly for many...

  14. A review of Arbuckle Group strata in Kansas from a sedimentologic perspective: Insights for future research from past and recent studies

    Science.gov (United States)

    Franseen, E.K.

    2000-01-01

    Arbuckle Group and equivalent-age rocks (Cambrian and Lower Ordovician) represent an important record of sediment deposition in the history of the North American continent and they contain important accumulations of hydrocarbons (oil and gas) and base metal deposits. This is true for Kansas as well where Arbuckle strata account for approximately 40% of the volume of produced petroleum and known reserves. However, in comparison to their counterparts in other areas, such as the Ellenburger and Knox, Arbuckle rocks in Kansas remain relatively understudied, especially with respect to sedimentology and diagenesis. The Arbuckle is present in the subsurface in most of Kansas and is absent only in areas of northeastern and northwestern Kansas, and over ancient uplifts and buried Precambrian highs. Arbuckle rocks thicken from north to south and are up to 1,390 feet in the southeastern corner of Kansas. Arbuckle Group and equivalent-age rocks from Kansas and surrounding areas are similar, consisting of platform deposits dominated by ramp-type subtidal to peritidal carbonates (mostly dolomitized) which can be subdivided into cycles, less than 0.5 m to 40 m thick, based on facies type and depositional patterns. Recent studies from central Kansas show that major depositional facies consist of coarse-grained packstones/ grainstones, fine-grained packstones/wackestones/mudstones, stromatolites-thrombolites, intraclastic conglomerate and breccia, and shale. In addition, secondary features include dolomitization, breccia, fracture, and conglomerate related to early subaerial exposure and later karst, burial or structural processes, silicification, and local mineralization. Arbuckle and equivalent strata in the Midcontinent were affected by prolonged subaerial exposure that began immediately after Arbuckle deposition, forming the sub-Tippecanoe to sub-Absaroka unconformity. Favorable reservoir qualities generally are thought to be related directly to basement structural elements and

  15. Local regularity analysis of strata heterogeneities from sonic logs

    Directory of Open Access Journals (Sweden)

    S. Gaci

    2010-09-01

    Full Text Available Borehole logs provide geological information about the rocks crossed by the wells. Several properties of rocks can be interpreted in terms of lithology, type and quantity of the fluid filling the pores and fractures.

    Here, the logs are assumed to be nonhomogeneous Brownian motions (nhBms which are generalized fractional Brownian motions (fBms indexed by depth-dependent Hurst parameters H(z. Three techniques, the local wavelet approach (LWA, the average-local wavelet approach (ALWA, and Peltier Algorithm (PA, are suggested to estimate the Hurst functions (or the regularity profiles from the logs.

    First, two synthetic sonic logs with different parameters, shaped by the successive random additions (SRA algorithm, are used to demonstrate the potential of the proposed methods. The obtained Hurst functions are close to the theoretical Hurst functions. Besides, the transitions between the modeled layers are marked by Hurst values discontinuities. It is also shown that PA leads to the best Hurst value estimations.

    Second, we investigate the multifractional property of sonic logs data recorded at two scientific deep boreholes: the pilot hole VB and the ultra deep main hole HB, drilled for the German Continental Deep Drilling Program (KTB. All the regularity profiles independently obtained for the logs provide a clear correlation with lithology, and from each regularity profile, we derive a similar segmentation in terms of lithological units. The lithological discontinuities (strata' bounds and faults contacts are located at the local extrema of the Hurst functions. Moreover, the regularity profiles are compared with the KTB estimated porosity logs, showing a significant relation between the local extrema of the Hurst functions and the fluid-filled fractures. The Hurst function may then constitute a tool to characterize underground heterogeneities.

  16. Rapid True Polar Wander Oscillations Preserved In Continuous Orosirian Strata

    Science.gov (United States)

    Mitchell, R. N.; Hoffman, P. F.; Brenner, A.; Xu, X.; Evans, D. A.; Bowring, S. A.; Bleeker, W.

    2014-12-01

    Previous paleomagnetic study of the Orosirian (2050-1800 Ma) Great Slave Supergroup, well exposed on islands in Great Slave Lake on the southeastern margin of the Slave craton, revealed evidence of a regularly reversing, or oscillatory, apparent polar wander path. The paleogeographic utility of paleopoles from the Great Slave Supergroup has been brought into question owing to the possibility of vertical-axis rotations associated with the McDonald transcurrent fault array, but structural corrections can be applied. In a high-resolution paleomagnetic re-sampling of portions of the Great Slave Supergroup, concentrating on the Pethei and Christie Bay Groups in particular, we demonstrate systematic and correlative shifts in declination within structurally uniform homoclinal sections. Positive fold tests further substantiate the primary nature of the paleomagnetic oscillations. Smooth, albeit rapid, declination changes preserved within and between our Great Slave Supergroup sections cannot be trivially explained by structural rotation. True polar wander oscillations (expressed as declination variation locally) may be used to correlate Orosirian strata regionally and globally. Geochronological refinement of the Great Slave Supergroup, both directly and indirectly, should help facilitate any such correlations and those with intrusive rocks both locally and globally. Unconformably overlain by the Et-Then Group that is contemporaneous with the McDonald Fault system, the Great Slave basin and intrusive Compton laccoliths pre-date transcurrent faulting. Increased precision achieved using modern U-Pb (zircon) geochronologic methods on the ca. 1865 Ma Compton laccoliths calibrates the minimum age constraint for Great Slave deposition. Additionally, magnetic susceptibility of a ~350 m-thick section of the Pethei Group reveals a hierarchy of cycles. If interpreted as astronomical cycles, possibly expressed through the effects of insolation on biogenic carbonate precipitation

  17. Local regularity analysis of strata heterogeneities from sonic logs

    Science.gov (United States)

    Gaci, S.; Zaourar, N.; Hamoudi, M.; Holschneider, M.

    2010-09-01

    Borehole logs provide geological information about the rocks crossed by the wells. Several properties of rocks can be interpreted in terms of lithology, type and quantity of the fluid filling the pores and fractures. Here, the logs are assumed to be nonhomogeneous Brownian motions (nhBms) which are generalized fractional Brownian motions (fBms) indexed by depth-dependent Hurst parameters H(z). Three techniques, the local wavelet approach (LWA), the average-local wavelet approach (ALWA), and Peltier Algorithm (PA), are suggested to estimate the Hurst functions (or the regularity profiles) from the logs. First, two synthetic sonic logs with different parameters, shaped by the successive random additions (SRA) algorithm, are used to demonstrate the potential of the proposed methods. The obtained Hurst functions are close to the theoretical Hurst functions. Besides, the transitions between the modeled layers are marked by Hurst values discontinuities. It is also shown that PA leads to the best Hurst value estimations. Second, we investigate the multifractional property of sonic logs data recorded at two scientific deep boreholes: the pilot hole VB and the ultra deep main hole HB, drilled for the German Continental Deep Drilling Program (KTB). All the regularity profiles independently obtained for the logs provide a clear correlation with lithology, and from each regularity profile, we derive a similar segmentation in terms of lithological units. The lithological discontinuities (strata' bounds and faults contacts) are located at the local extrema of the Hurst functions. Moreover, the regularity profiles are compared with the KTB estimated porosity logs, showing a significant relation between the local extrema of the Hurst functions and the fluid-filled fractures. The Hurst function may then constitute a tool to characterize underground heterogeneities.

  18. Interpretation and mapping of carbonate mounds within the Ordovician on Gotland, Sweden

    Science.gov (United States)

    Levendal, Tegan; Sopher, Daniel; Juhlin, Christopher

    2017-04-01

    Oljeprospecketering AB (OPAB), a Swedish state owned company, acquired an extensive data set in the 1970s and 1980s for the purposes of hydrocarbon exploration. This OPAB data set is largely unpublished and consists of over 300 well data reports and logs and over 33000 km of 2D marine seismic data, as well as land seismic data from the island of Gotland. In this study we use processed land seismic profiles from Gotland and well data to interpret the thickness of the Ordovician across the island. As well as gain insight into the internal stratigraphy and structural framework of the Ordovician. The Ordovician sequence is 100-150 m thick consisting of three formations (Fm), informally defined by OPAB, the Bentonitic Limestone Fm, the Kvarne Fm and the Klasen Fm. Carbonate mounds are locally formed from siliciclastic rich muds. In the lower sequences carbonate mounds are present that are observed both in the seismic and well data. These mounds were of great interest during the exploration phase since they are sometimes host to hydrocarbon accumulations. In the present study we place emphasis on mapping the size, distribution and density of the carbonate mounds within the Ordovician. The original driving force for the development of these mounds are related to sea level and climate changes during deposition. Post depositional erosion, biotic factors and basin evolution also played a role in their development. During the Late Ordovician-Early Silurian, Baltica moved northwards towards the equator resulting in a typical depositional environment consisting of proximal coastal areas, and transgressive, lowstand shelf settings conducive to mound development. The mounds act as potential reservoirs, in the form of isolated bodies of limestone capped by tabular and tight argillaceous limestones acting as a cap rock. To date studies of carbonate mound features have primarily focused on detailed analysis of well log, core and outcrop information. This extensive dataset therefore

  19. 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......-carbonates (Fe-carb), iron-oxides (Fe-ox), magnetite (Fe-mag), and pyrite (FeP) was examined. Overall, the multi-proxy sedimentary geochemical data suggest that the succession containing pyritized trilobite beds was deposited under a dysoxic water-column, in agreement with the paleontological data. The data do...

  20. 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...

  1. 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...... Era: novel morphologies appearing through the Cambrian and subsequently diversifying in the Ordovician. Well-preserved specimens were extracted following a standard palynological method and studied by light-transmitted microscopy. The galeate plexus acritarchs Caldariola, Priscogalea...... alga Acetabularia (Chlorophyta), which possesses an intrinsic lid-forming apparatus used during the organism's reproductive stage. Based on the observations on the fossil material and studies on the Acetabularia lid formation, we propose a model of operculum formation in the galeate plexus micro...

  2. 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......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 palaeoenvironment along the margin of northeastern Gondwana. The brachiopods from the Stairway Sandstone are of low diversity and represent ca 9% of the entire shelly fauna. Five brachiopod taxa are described from the Stairway Sandstone; all are endemic to the Amadeus Basin at species level. Two new species...

  3. Forming mechanism of the Ordovician karst carbonate reservoirs on the northern slope of central Tarim Basin

    Directory of Open Access Journals (Sweden)

    Heng Fu

    2017-07-01

    Full Text Available The Ordovician karst carbonate reservoirs on the northern slope of central Tarim Basin are important oil and gas exploration targets in the basin, but their dissolution mechanisms are in controversy. In this paper, based on the integrated study of sedimentation, sequence and reservoir, together with microscopic analysis and macroscopic seismic data analysis, the carbonate karst reservoirs in the study area were divided into three types: dissolved pore-cavity limestone reservoir, pore-cavity dolomite reservoir and fracture-cavity siliceous reservoir, and their forming mechanisms were discussed respectively. Some findings were obtained. First, dissolved pore-cavity limestone reservoirs are distributed in the upper Yingshan Fm and Yijianfang Fm of the Ordovician vertically, while pore-cavity dolomite reservoirs are mainly developed in the Penglai Fm and lower Yingshan Fm of the Ordovician with great thickness. Second, dissolved pore-cavity limestone reservoirs were formed by karstification on the third-order sequence boundary (lowstand tract, while pore-cavity dolomite reservoirs were formed by deep burial dolomitization controlled by karstification on the third-order sequence boundary, both of which are distributed in the highstand tract below the third-order sequence boundary. Third, siliceous reservoirs are developed under the control of faulting, as a result of reworking of deep hydrothermal fluids along faults to the limestone, and the siliceous reservoirs and their hydrothermal solution fracture-cavity systems are distributed near faults. It is further predicted that, in addition to the three types of reservoir above, platform-margin reef-flat reservoirs are developed in the Ordovician on the northern slope of central Tarim Basin.

  4. Cracking and thermal maturity of Ordovician oils from Tahe Oilfield, Tarim Basin, NW China

    Directory of Open Access Journals (Sweden)

    Anlai Ma

    2017-12-01

    Full Text Available The thermal maturity of the Ordovician oils from the Tahe oilfield of Tarim Basin, NW China was assessed through various maturity parameters, such as biomarkers, aromatic parameters, and diamondoid parameters. Both Ts/(Ts+Tm and C29Ts/(C29H+C29Ts values indicate that the maturity of oils has not reached the condensates stage, which is consistent with the maturity obtained by MPI1. However, the diamondoid maturity suggests that the oil maturity ranges 1.1%–1.6% Ro, which is apparently higher than that of the maturity obtained by the biomarker and MPI1. This discrepancy in maturity may indicate that the Ordovician reservoir has multiple filling history. The 4-MD+3-MD concentration of oils disperses and increases slowly when the Ts/(Ts+Tm value is lower than 0.55. Meanwhile, the value increases rapidly when the Ts/(Ts+Tm value is higher than 0.55. It is proposed that the diamondoid baseline is about 15 μg/goil for marine oils in the Tahe oilfield based on the diamondoid concentration of marine oils from reservoirs of various age. The concentration of 4-MD+3-MD of most Ordovician oils generally ranges from 4.5 to 35 μg/goil, suggesting that the degree of oil-cracking is lower than 50% and the deep Ordovician have potential of oil exploration. The distribution of the concentration of 4-MD+3-MD is characterized by being high in the east and south, low in the west and north, proposing that the two migration pathways exit in the oilfield, which are from east to west and from south to north, respectively. The migration directions are consistent with the results obtained from the oil density and the maturity parameters such as Ts/(Ts+Tm. Thus, suggesting the concentration of 4-MD+3-MD can be used as migration index in oilfield scale.

  5. Cambrian and Ordovician Fossil-Lagerstätten in the Barrandian area

    Czech Academy of Sciences Publication Activity Database

    Fatka, O.; Budil, P.; Kraft, P.; Mergl, M.; Mikuláš, Radek; Valent, M.; Lajblová, K.; Rak, Š.; Steinová, M.; Szabad, M.; Micka, V.; Aubrechtová, M.; Lajbl, L.; Nohejlová, M.; Vodička, J.

    2012-01-01

    Roč. 18, č. 1 (2012), s. 22-25 ISSN 1212-6209. [Congress of CGS and SGS. Moninec, 2011.09.22-2011.09.25] R&D Projects: GA ČR GA205/06/0395; GA ČR GA205/09/1521 Institutional research plan: CEZ:AV0Z30130516 Keywords : Cambrian * Ordovician * Fossil-Lagerstätten Subject RIV: DB - Geology ; Mineralogy http://www.sci.muni.cz/gap/casop/

  6. Epibiont relationships on hyolithids demonstrated by Ordovician trepostomes (Bryozoa) and Devonian tabulates (Anthozoa)

    Czech Academy of Sciences Publication Activity Database

    Galle, Arnošt; Parsley, R. L.

    2005-01-01

    Roč. 80, č. 2 (2005), s. 125-138 ISSN 1214-1119 R&D Projects: GA ČR(CZ) GA205/02/1576 Institutional research plan: CEZ:AV0Z3013912 Keywords : epibionts * obligate and facultative symbiosis * mutualism * Ordovician * Devonian * Hyolithida * Tabulata * Bryozoa Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/bulletin/contents/2005/vol80no2/125_galle.pdf

  7. A mineral reconnaissance survey of the Llandrindod Wells/Builth Wells Ordovician inlier, Powys

    OpenAIRE

    Marshall, T.R.; Leake, R.C.; Rollin, K.E.

    1987-01-01

    A reconnaissance drainage geochemical survey was carried out at a density of about 2 samples per km2 of the Llanclrindod Wells/ Builth Wells Ordovician inlier in Powys. The rocks of the area comprise a sequence of mudstones and shales ranging in age from the Llan\\.irn to the Caradoc containing volcanic horizons and a lrolcanic complex of acid/intermediate composition overlain in the south by a further volcanic sequence of more basic composition. An area of about 65 km2...

  8. 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.

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27385026

  10. Review of the Ordovician stratigraphy and fauna of the Anarak Region in Central Iran

    Science.gov (United States)

    Popov, Leonid E.; Hairapetian, Vachik; Evans, David H.; Pour, Mansoureh Ghobadi; Holmer, Lars E.; Baars, Christian

    2015-12-01

    The Ordovician sedimentary succession of the Pol-e Khavand area, situated on the northern margin of the Yazd block, has important differences from those in other parts of Central Iran. It has been established that the presumably terminal Cambrian to Lower Ordovician volcano-sedimentary Polekhavand Formation, exposed in the Pol-e Khavand area, has non-conformable contact with greenschists of the Doshakh Metamorphic Complex. The succeeding, mainly siliciclastic Chahgonbad Formation contains low to moderately diverse faunal assemblages, including brachiopods, cephalopods, trilobites and tentaculitids. The Darriwilian age of the lower part of the formation is well established by the co-occurrence of brachiopod genera Camerella, Phragmorthis, Tritoechia and Yangtzeella. The associated rich cephalopod fauna is different from the Darriwilian cephalopod associations of the Alborz terrane and may show some affinity with warm water faunas of North China and South Korea. It is likely that the Mid Ordovician fauna recovered from the lower part of the Chahgonbad Formation settled in the area sometime during a warming episode in the late Darriwilian. By contrast the low diversity mid Katian brachiopod association includes only three taxa, which occur together with the trilobite Vietnamia cf. teichmulleri and abundant, but poorly preserved tentaculitids questionably assigned to the genus Costatulites. This faunal association bears clear signatures linking it to the contemporaneous cold water faunas of the Arabian, Mediterranean and North African segments of Gondwana. Four brachiopod species recovered from the Chahgonbad Formation, including Hibernodonta lakhensis, Hindella prima, Lomatorthis? multilamellosa and Yangtzeella chupananica are new to science.

  11. Trace fossils of Ordovician radiolarian chert and siliceous mudstone in Newfoundland, Canada

    Science.gov (United States)

    Kakuwa, Yoshitaka

    2017-08-01

    Ordovician radiolarian chert and siliceous mudstone in Newfoundland are examined to elucidate the development of trace fossils in and on the Early Paleozoic ocean bottom. Chert sedimentation in the Shoal Arm Formation (SAF) is limited to a short interval, but its sedimentation rate is high with few siliciclastic materials. Trace fossils are common in chert in the SAF, but their development is interrupted by frequent anoxic events. The trace fossils are larger than trace fossils in the contemporary chert of other areas. In contrast, trace fossils in the Strong Island Chert (SIC) are moderately-sized to small, with a few sandstone beds interbedded with chert. Those characteristics reflect differences in the sedimentary environments. Rocks of the SIC were deposited in a basinal part of a back-arc basin; whereas, those in the SAF were deposited on a small isolated basin. Red chert or siliceous rocks that underlie grey cherts and siliceous rocks of the SIC and the SAF bear small and simple trace fossils. This is a common feature of ;oceanic red rocks.; Radiolarian chert and siliceous rocks in Newfoundland also showed that trace fossils are widespread by the Middle Ordovician in the deep-sea environment. The Great Ordovician Biodiversification Event is confirmed in the radiolarian siliceous rocks there.

  12. New data on acritarchs from the Upper Ordovician of the Tungus basin, Siberian Platform

    Directory of Open Access Journals (Sweden)

    Elena Raevskaya

    2014-12-01

    Full Text Available Distinctive late Ordovician acritarch assemblages have been discovered for the first time from about a 100 m sedimentary succession exposed along the Bol¢shaya Nirunda River in Siberia. The studied stratigraphic interval includes the uppermost Baksian, Dolborian, Nirundian and Burian regional stages, which correspond to the Katian–?lowermost Hirnantian global stages. Acritarch assemblages from the Dolbor Regional Stage are exceptionally diverse and include aside from the long-ranging taxa several unique (endemic morphotypes and a number of distinctive stratigraphically valuable species, well known outside Siberia. The occurrence of the acritarchs widespread outside Siberia is potentially important for interregional bio­stratigraphic correlations and might also play a significant role in biogeographic reconstructions. Having in mind that the Siberian palaeocontinent was located in a low-latitude tropical area during the entire Ordovician, the presence of taxa typical of cold-water settings along the Peri-Gondwana margin can be regarded as an additional evidence for penetration of cool-water currents into the epicontinental Tungus basin in the Upper Ordovician.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Obtaining Strata Boundaries under Proportional Allocation with Varying Cost of Every Unit

    Directory of Open Access Journals (Sweden)

    Faizan Danish

    2017-09-01

    Full Text Available One of the main reasons for stratifying the population is to produce a gain in precision of the estimates, in the sample surveys. For achieving this, one of the problem is determination of optimum strata boundaries. The strata boundaries should be obtained in such a way, so that it can reasonably expect to reduce the cost of the survey as much as possible without sacrificing the accuracy or alternatively, reducing the margin of error to the greatest possible extent for the same expected cost. In this paper, we have discussed the way of obtaining optimum strata boundaries when the cost of every unit varies in the whole strata. The problem is formulated as non-linear programming problem which is solved by using Bellman’s principle of optimality. For numerical illustration an example is presented for uniformly distributed study variable.

  15. Wafer level Integration on PolyStrata(R) Interposer (WIPI) (17013), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Nuvotronics will develop a robust wafer-level integration technology using our proprietary PolyStrata interposer to enable high-frequency interconnects and routing...

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

    Science.gov (United States)

    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

  17. Slope-apron deposition in an ordovician arc-related setting: The Vuelta de Las Tolas Member (Suri Formation), Famatina Basin, northwest Argentina

    Science.gov (United States)

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

    1997-01-01

    The Ordovician Suri Formation is part of the infill of the Famatina Basin of northwest Argentina, which formed in an active setting along the western margin of early Paleozoic Gondwana. The lower part of this formation, the Vuelta de Las Tolas Member, records sedimentation on a slope apron formed in an intra-arc basin situated on a flooded continental arc platform. The coincidence of a thick Arenig-Llanvirn sedimentary succession and volcanic-plutonic arc rocks suggests an extensional or transtensional arc setting, and is consistent with evidence of an extensional regime within the volcanic arc in the northern Puna region. The studied stratigraphic sections consist of volcanic rocks and six sedimentary facies. The facies can be clustered into four facies associations. Association 1, composed of facies A (laminated siltstones and mudstones) and B (massive mudstones and siltstones), is interpreted to have accumulated from silty-muddy high-and low-density turbidity currents and highly fluid, silty debris flows, with subsequent reworking by bottom currents, and to a lesser extent, hemipelagic suspension in an open-slope setting. Facies association 2 is dominated by facies C (current-rippled siltstones) strata. These deposits are interpreted to record overbank sedimentation from fine-grained turbidity currents. Facies E (matrix-supported volcanic breccias) interbedded with andesitic lava units comprises facies association 3. Deposition was contemporaneous with subaqueous volcanic activity, and accumulated from cohesive debris flows in a coarse-grained wedge at the base of slope. Facies association 4 is typified by facies D (vitric fine-grained sandstones and siltstones) and F (channelized and graded volcanic conglomerates and breccias) deposits. These strata commonly display thinning-and fining-upward trends, indicating sedimentation from highly-concentrated volcaniclastic turbidity currents in a channelized system. The general characteristics of these deposits of fresh

  18. Model for the prediction of subsurface strata movement due to underground mining

    Science.gov (United States)

    Cheng, Jianwei; Liu, Fangyuan; Li, Siyuan

    2017-12-01

    The problem of ground control stability due to large underground mining operations is often associated with large movements and deformations of strata. It is a complicated problem, and can induce severe safety or environmental hazards either at the surface or in strata. Hence, knowing the subsurface strata movement characteristics, and making any subsidence predictions in advance, are desirable for mining engineers to estimate any damage likely to affect the ground surface or subsurface strata. Based on previous research findings, this paper broadly applies a surface subsidence prediction model based on the influence function method to subsurface strata, in order to predict subsurface stratum movement. A step-wise prediction model is proposed, to investigate the movement of underground strata. The model involves a dynamic iteration calculation process to derive the movements and deformations for each stratum layer; modifications to the influence method function are also made for more precise calculations. The critical subsidence parameters, incorporating stratum mechanical properties and the spatial relationship of interest at the mining level, are thoroughly considered, with the purpose of improving the reliability of input parameters. Such research efforts can be very helpful to mining engineers’ understanding of the moving behavior of all strata over underground excavations, and assist in making any damage mitigation plan. In order to check the reliability of the model, two methods are carried out and cross-validation applied. One is to use a borehole TV monitor recording to identify the progress of subsurface stratum bedding and caving in a coal mine, the other is to conduct physical modelling of the subsidence in underground strata. The results of these two methods are used to compare with theoretical results calculated by the proposed mathematical model. The testing results agree well with each other, and the acceptable accuracy and reliability of the

  19. Effects of mine strata thermal behavior and mine initial temperatures on mobile refuge alternative temperature.

    Science.gov (United States)

    Yantek, D S; Yan, L; Bissert, P T; Klein, M D

    2017-04-01

    Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines. Mobile RAs have a limited ability to dissipate heat, and heat buildup can lead to a life-threatening condition as the RA internal air temperature and relative humidity increase. The U.S. National Institute for Occupational Safety and Health (NIOSH) performed heat testing on a 10-person tent-type training RA and contracted ThermoAnalytics Inc. to develop a validated thermal simulation model of the tested RA. The model was used to examine the effects of the constant mine strata temperature assumption, initial mine air temperature, initial mine strata surface temperature (MSST), initial mine strata temperature at depth (MSTD) and mine strata thermal behavior on RA internal air temperature using 117 W (400 Btu/h) of sensible heat input per simulated miner. For the studied RA, when the mine strata temperature was treated as a constant, the final predicted RA internal air temperature was 7.1°C (12.8°F) lower than it was when the mine strata thermal behavior was included in the model. A 5.6°C (10.0°F) increase in the initial MSST resulted in a 3.9°C (7.1°F) increase in the final RA internal air temperature, whereas a 5.6°C (10°F) increase in the initial MSTD yielded a 1.4°C (2.5°F) increase in the final RA internal air temperature. The results indicate that mine strata temperature increases and mine strata initial temperatures must be accounted for in the physical testing or thermal simulations of RAs.

  20. Maxwell Strata and Cut Locus in the Sub-Riemannian Problem on the Engel Group

    Science.gov (United States)

    Ardentov, Andrei A.; Sachkov, Yuri L.

    2017-12-01

    We consider the nilpotent left-invariant sub-Riemannian structure on the Engel group. This structure gives a fundamental local approximation of a generic rank 2 sub-Riemannian structure on a 4-manifold near a generic point (in particular, of the kinematic models of a car with a trailer). On the other hand, this is the simplest sub-Riemannian structure of step three. We describe the global structure of the cut locus (the set of points where geodesics lose their global optimality), the Maxwell set (the set of points that admit more than one minimizer), and the intersection of the cut locus with the caustic (the set of conjugate points along all geodesics). The group of symmetries of the cut locus is described: it is generated by a one-parameter group of dilations R+ and a discrete group of reflections Z2 × Z2 × Z2. The cut locus admits a stratification with 6 three-dimensional strata, 12 two-dimensional strata, and 2 one-dimensional strata. Three-dimensional strata of the cut locus are Maxwell strata of multiplicity 2 (for each point there are 2 minimizers). Two-dimensional strata of the cut locus consist of conjugate points. Finally, one-dimensional strata are Maxwell strata of infinite multiplicity, they consist of conjugate points as well. Projections of sub-Riemannian geodesics to the 2-dimensional plane of the distribution are Euler elasticae. For each point of the cut locus, we describe the Euler elasticae corresponding to minimizers coming to this point. Finally, we describe the structure of the optimal synthesis, i. e., the set of minimizers for each terminal point in the Engel group.

  1. Assessment of strata control in mine vertical shafts by means of the critical equilibrium method

    Energy Technology Data Exchange (ETDEWEB)

    Fisenko, G.L.; Kozel, A.M.; Adamskii, V.V.

    1983-02-01

    The paper analyzes problems associated with strata control in mine shafts excavated in weak rocks such as clay or argillite. Standardized shaft liners used under these conditions do not prevent shaft deformation and damage. Investigations carried out in the Donbass and the Dobruya basin in Bulgaria show that liner deformation and damage depends on compression strength of weak rocks and mining depth. In the Dobruya basin a clay layer is situated at a depth of 600 m. Interaction between shaft liners and the surrounding weak rock strata is analyzed. Equations for calculating the minimum thickness of shaft liners considering mechanical properties of the liners, number of layers which form a shaft liner and mechanical properties of rocks are derived. Recommendations on liner types and dimensions at mining depths from 100 m to 1500 m are made. Considering that shaft liner displacement under conditions of weak rock strata is not limited by the interaction between liners and rock strata, shaft liner design should also take into consideration intensive bending moments. Increasing liner thickness does not prevent liner deformation under conditions of intensive strains. Experiments carried out in the Donbass show that multilayer liners are an efficient method for strata control. A system being tested by VNIMI is described: space between the rigid shaft liners made of concrete and the surrounding weak strata is filled with concrete stones which form a yielding shaft cover. (8 refs.)

  2. Provenance and paleogeography of the Mesozoic strata in the Muang Xai Basin, northern Laos: petrology, whole-rock geochemistry, and U-Pb geochronology constraints

    Science.gov (United States)

    Wang, Yanlu; Wang, Licheng; Wei, Yushuai; Shen, Lijian; Chen, Ke; Yu, Xiaocan; Liu, Chenglin

    2017-06-01

    The Muang Xai Basin, located in northern Laos, is associated with the Simao, Vientiane, and Khorat Basins. The paleogeographic link of these basins has not been investigated in great detail; thus, the investigation presented in this study is a comprehensive analysis of petrology, whole-rock geochemistry, and detrital zircon U-Pb chronology used to characterize the provenance of the Muang Xai Basin. Results suggest that the sedimentary source includes felsic rocks from an active continental margin or continental arc with minor amounts of recycled passive continental margin sediments. Sandstones of the Muang Xai Basin contain detrital zircons with varying U-Pb peak ages. The youngest age peak of all the zircons is 103 Ma, which limits the age of the Mesozoic strata to the Late Cretaceous. Detrital zircon U-Pb and trace element data, combined with geochemical result, reveal that the pre-Ordovician zircons were derived from recycled sediments of the Yangtze Block, which are originally sourced from the Qinling Orogenic belt. This provenance is shared with coeval sediments in the Simao and Khorat Basins, while magmatic rocks of the Ailaoshan, Truong Son Belt, and Lincang terrane are responsible for zircons of 416-466 and 219-308 Ma in age. Zircons of 101-110 and 149-175 Ma in age were sourced from magmatic rocks of the southwestern South China Block and northern Vietnam. These provenance results suggest that sediments flow into the Khorat red beds was likely from the Great Simao Basin and northern Vietnam, and not directly from the Yangtze Block.

  3. Thermal maturity patterns (CAI and %R%) in the Ordovician and Devonian rocks of the Appalachian basin in New York State

    Science.gov (United States)

    Weary, David J.; Ryder, Robert T.; Nyahay, Richard

    2000-01-01

    The objective of this study is to enhance existing thermal maturity maps in New York State by establishing: 1) new subsurface CAI data points for the Ordovician and Devonian and 2) new %Ro and Rock Eval subsurface data points for Middle and Upper Devonian black shale units. The thermal maturity of the Ordovician and Devonian rocks is of major interest because they contain the source for most of the unconventional natural gas resources in the basin. Thermal maturity patterns of the Middle Ordovician Trenton Group are evaluated here because they closely approximate those of the overlying Ordovician Utica Shale that is believed to be the source rock for the regional oil and gas accumulation in Lower Silurian sandstones (Jenden and others, 1993; Ryder and others, 1998). Improved CAI-based thermal maturity maps of the Ordovician are important to identify areas of optimum gas generation from the Utica Shale and to provide constraints for interpreting the origin of oil and gas in the Lower Silurian regional accumulation, in particular, its basin-centered part (Ryder, 1998). Thermal maturity maps of the Devonian will better constrain burial history-petroleum generation models of the Utica Shale, as well as place limitations on the origin of regional oil and gas accumulation in Upper Devonian sandstone and Middle to Upper Devonian black shale.

  4. Deciphering evolutionary strata on plant sex chromosomes and fungal mating-type chromosomes through compositional segmentation.

    Science.gov (United States)

    Pandey, Ravi S; Azad, Rajeev K

    2016-03-01

    Sex chromosomes have evolved from a pair of homologous autosomes which differentiated into sex determination systems, such as XY or ZW system, as a consequence of successive recombination suppression between the gametologous chromosomes. Identifying the regions of recombination suppression, namely, the "evolutionary strata", is central to understanding the history and dynamics of sex chromosome evolution. Evolution of sex chromosomes as a consequence of serial recombination suppressions is well-studied for mammals and birds, but not for plants, although 48 dioecious plants have already been reported. Only two plants Silene latifolia and papaya have been studied until now for the presence of evolutionary strata on their X chromosomes, made possible by the sequencing of sex-linked genes on both the X and Y chromosomes, which is a requirement of all current methods that determine stratum structure based on the comparison of gametologous sex chromosomes. To circumvent this limitation and detect strata even if only the sequence of sex chromosome in the homogametic sex (i.e. X or Z chromosome) is available, we have developed an integrated segmentation and clustering method. In application to gene sequences on the papaya X chromosome and protein-coding sequences on the S. latifolia X chromosome, our method could decipher all known evolutionary strata, as reported by previous studies. Our method, after validating on known strata on the papaya and S. latifolia X chromosome, was applied to the chromosome 19 of Populus trichocarpa, an incipient sex chromosome, deciphering two, yet unknown, evolutionary strata. In addition, we applied this approach to the recently sequenced sex chromosome V of the brown alga Ectocarpus sp. that has a haploid sex determination system (UV system) recovering the sex determining and pseudoautosomal regions, and then to the mating-type chromosomes of an anther-smut fungus Microbotryum lychnidis-dioicae predicting five strata in the non

  5. 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.

  6. 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.

  7. Depositional facies mosaics and their time lines in Lower Ordovician carbonates of central Appalachians

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, C.T.; Goldhammer, R.K.; Hardie, L.A.

    1985-02-01

    A comparative sedimentology and facies stratigraphy study of the Lower Ordovician carbonate of the central Appalachians (Beekmantown Group and equivalents) has been carried out. Our approach used subfacies (rock record of subenvironments) as the basin units of section measurement. The authors differentiated related sets of subfacies into larger facies units (rock record of environments). Facies were then correlated from section to section using fossils and lithostratigraphy to make a 3-dimensional facies mosaic. Within this mosaic, time lines were constructed using onlap-offlap tongues and cyclic sequences. These time lines cut across facies boundaries. Using this approach, the authors have established that the lower 600 m of the Lower Ordovician carbonate sequence is made up of 4 main facies: (1) cyclic laminite facies composed of a package of shoaling-upward shelf lagoon-peritidal cycles, (2) thin-bedded grainstone facies deposited in a shelf lagoon, (3) Renalcis bioherm facies recording a shelf lagoon patch-reef environment, and (4) Epiphyton bioherm facies recording a shelf-edge reef system. The distribution of these facies along time lines across the strike of the central Appalachians is markedly zoned. Epiphyton bioherm facies dominate the eastern margin while cyclic laminite facies dominate the western margin, with thin-bedded grainstone and Renalcis bioherm facies making up the central belt. This zonation of facies is a typical shallow carbonate shelf system with fringing reefs along the eastern, seaward margin and tidal flats along the western, landward margin. Vertical distribution of these facies across strike records 3 major sea level changes during deposition of the lower 600 m of this extensive Lower Ordovician carbonate shelf.

  8. Diagenetic modification of Knox evaporative-dolomite geochemistry by middle Ordovician paleoaquifer/burial fluids

    Energy Technology Data Exchange (ETDEWEB)

    Montanez, I.P.; Read, J.F.

    1986-05-01

    Early Ordovician upper Knox cyclic carbonates (100,000-year periods) were deposited on a ramp in a semiarid setting. Inner ramp facies are completely dolomitized, whereas only cycle caps on the outer ramp are dolomite. Laminite caps on leading edges of prograding flats were dolomitized by evaporative, storm-recharged marine waters that precipitated CoCO/sub 3/ and minor amounts of CaSO/sub 4/. Subtidal facies beneath interiors of supratidal flats (up to 200 km wide)were dolomitized by shallow subsurface brines as the flats prograded. Inner ramp areas existed as supretidal flats for as long as 100,000 years, hence only there are sequences completely dolomitized. Tidal-flat dolomites consist of euhedral to subhedral fabric preservation mosaics (crystals 5-50 ..mu..m, and up to 300 ..mu..m in replaced pelletal layers). Dolomitized subtidal sediments are composed of 20-200 ..mu..m dolomite crystals. Most of the early dolomites are fabric retentive initially, becoming more fabric destructive with increasing exposure to dolomitizing fluids. Fe values are up to 2000 ppm, and Mn values are up to 500 ppm. delta/sup 18/O values show strong geographic control, with samples depleted (up to - 7 per thousand) relative to pristine evaporative dolomites derived from concentrated Ordovician seawater. Burial dolomites are enriched in Fe (up to 14,000 ppm) and depleted in delta/sup 18/O, suggesting precipitation from basinal brines at elevated temperatures. Geochemical data suggest that evaporative dolomites have undergone modification by isotopically lighter fluids. Alteration most likely occurred within a Middle Ordovician meteoric aquifer system or less likely by later Paleozoic basinal brines. Regional geologic data for Knox Group carbonates throughout the eastern US are vital in constraining dolomitization models.

  9. 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.

  10. 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

  11. Silurian Micrometeorite Flux: The Demise of the Mid-Ordovician L-Chondrite Reign.

    Science.gov (United States)

    Martin, E.; Schmitz, B.

    2017-12-01

    Earth's sedimentary record holds information about the micrometeorite flux through time, reflecting the collisional evolution of the asteroid belt. Around 466 Ma ago in the mid-Ordovician period the L-chondrite parent body breakup (LCPB) took place in the main asteroid belt causing a massive increase, up to two orders of magnitude, in the flux of meteorites to Earth (Schmitz, 2013). What did the meteorite flux look like after the breakup event? And when in time can we see a decrease in the fraction of L-chondritic micrometeorites? We dissolved in acids condensed, marine limestone representing the mid-Ordovician and the late Silurian about 0.5 and 40 Ma, respectively after the LCPB, and searched the residues for spinel grains from equilibrated ordinary chondrites (EC). We used 102 kg from the mid-Ordovician Komstad Limestone Formation, Killeröd quarry in Sweden, and 321 kg from the Silurian Kok Formation, Cellon section in Austria. Elemental analyses of the spinel grains were used to link the grains to different types of meteorites. In the large grain size fraction (63-355 µm) there are 4.5 EC grains/kg of rock in the mid-Ordovician sample and only 0.03 EC grains/kg in the Silurian sample. Because the two formations formed at about the same rate (a few mm per kyr) the results represent strong evidence for a major tailing off in the L-chondritic meteorite contribution by the late Silurian. The EC grains have been divided into the H, L, and LL groups based on the TiO2 content. The results show that the fraction of L chondrites compared to H and LL chondrites had declined significantly by the late Silurian. In the study of Heck et al. (2016) it was shown that ≥99% of the ordinary chondritic micrometeorites were L chondrites right after the LCPB. Our data indicate that the L-chondrite fraction had decreased to 60% by the Silurian, with the H and LL chondrites making up 30% and 10% respectively of the flux.

  12. 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.

  13. Disturbance and ecologic succession in an upper ordovician cobble-dwelling hardground fauna.

    Science.gov (United States)

    Wilson, M A

    1985-05-03

    An Ordovician hardground fauna in northern Kentucky provides an example from the fossil record of the maintenance of species diversity by periodic disturbance of an autogenic ecologic succession. The marine invirtebrates found encrusting limestone cobbles show an order of community development from a low-diversity pioneer assemblage through a high-diversity association to a monospecific stable fauna. All species, including the late successional dominants, were present in the early stages of colonization. Periodic overturning of the cobbles killed the encrusters and opened up new spaces on which succession was reinitiated. These disturbances maintained high diversity within the encrusting community by limiting the spatial distribution of the most efficient space competitors.

  14. 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.

  15. Stratigraphic and structural reconstruction of an Upper Ordovician super-eruption (Catalan Pyrenees)

    Science.gov (United States)

    Marti, Joan; Casas, Josep Maria; Muñoz, Josep A.

    2017-04-01

    Pre-Variscan basement of the Pyrenees includes evidence of many magmatic episodes represented by different types of granitoids and volcanic rocks, which indicates the complex geodynamic history of this peri-Gondwana terrane during Palaeozoic. One of the most significative magmatic episodes is that of Upper Ordovician (Caradocian) age, which is represented by several granitic and granodioritic bodies and volcanic rocks mostly of pyroclastic nature. In the Catalan Pyrenees this magmatism is well represented in the Ribes de Freser and Nuria area, where the orthogneisses from the Nuria massif and the Ribes granophyre, both with a similar age of 457 Ma, seem to form a calc-alkaline plutonic suite covering terms from deeper to shallower levels. The presence of numerous pyroclastic deposits and lavas interbedded with Caradocian sediments and intruded by and immediately above the Ribes granophyre, suggests that this intrusive episode also generated significant volcanism. The area also hosts an important volume of rhyolitic ignimbrites and andesitic lavas strongly affected by Alpine tectonics and commonly showing tectonised contacts at the base and top of the sequences. These volcanic rocks were previously attributed to the Upper Carboniferous late-Variscan volcanism, extensively represented in the Pyrenees. However, new laser ablation U-Pb zircon geochronology from these rocks has revealed an Upper Ordovician age ( 455 Ma), similar to that of the plutonic rocks of the same area, thus suggesting a probable genetic relation between all them. The palinspatic reconstruction of the Alpine and Variscan tectonic units that affect this area has permitted to infer the geometry, facies distribution, original position, and thickness of these volcanic rocks previously attributed to the late-Variscan volcanism, and reveals how they are spatially (and stratigraphically) associated with the previously identified Late Ordovician volcanic rocks. In particular, the volcanic rocks cropping

  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

    not uniformly distributed, nor was the succeeding recovery. Here we argue that changing plate tectonic configurations during the Ordovician–Silurian interval may have exerted a primary control on biotic extinction and recovery. In particular the proximity and ultimate loss of microcontinents and associated...... smaller terranes around Laurentia may have restricted shelf and slope habitats during the latest Ordovician but, nevertheless, in a contracted Iapetus Ocean, provided migration routes to help drive a diachronous early Silurian recovery. The conclusion that plate tectonics was a primary factor controlling...

  17. Studies on the Neogene Tertiary strata distributed in the central part of Tottori prefecture

    International Nuclear Information System (INIS)

    Yoshitani, Akihiko; Yoshizawa, Junko.

    1978-01-01

    The Neogene Tertiary strata, distributed in the central part of Tottori Prefecture, are volcano-stratigraphically classified, as shown in Figure 3. The Miocene strata are divided into Ojika formation and Mitoku formation in ascending order. Ojika formation, composed of plagio-rhyolitic pyroclastics and lavas, abuts against the basement rocks. Furthermore, some breaccias derived from the talus basal conglomerate beds are found in Ojika formation. Mitoku formation abuts both against the basement rocks and Ojika formation, and sometimes overlaps on the basement rocks. From the investigation into the Miocene strata, it is clarified that the depression took place prior to the volcanic activities at the earliest stage of the present Miocene sedimentary basin. (author)

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

    DEFF Research Database (Denmark)

    Moreau, Julien

    2011-01-01

    of the relict postglacial topography.The transgressive system, recognised for its good reservoir potential, is considered to play a key-role in the petroleum system, linking the source rock deposited in the ancient topographic lows with the reservoir rocks in the topographic highs.This study aims to demonstrate......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...... to an important hiatus, with the Rhuddanian deposits at the base of the remnant glacial troughs being 3Ma older than at the top of the topographic highs.The source-rock in theMurzuq Basin is of Early Rhuddanian age, so it is present only in the deepest partwhereas geomorphic traps are formedwithin the highs...

  19. The oldest iocrinid crinoids from the Early/Middle Ordovician of China: Possible paleogeographic implications

    Science.gov (United States)

    Lin, Jih-Pai; Ausich, William I.; Balinski, Andrzej; Bergström, Stig M.; Sun, Yuanlin

    2018-01-01

    This study reports new crinoid material, which is identified as Muicrinus dawanensis new genus and new species from South China, representing the oldest known iocrinid in the world. These new fossils, which are characterized by bearing simple primibrachials and a helically coiled column, are from the lower-middle part of the Dawan Formation, which ranges from the upper Floian (Lower Ordovician) to the lower Dapingian (Middle Ordovician) (∼470 Ma). A total of 11 related taxa with 80 characters were selected to conduct phylogenetic analyses. Our results indicated that South China specimens are closely related to ones that are endemic to Laurentia. Synapomorphies shared between species in those two cratons include elongate supraradial plates and isotomous arm branching. Furthermore, the phylogenetic closeness of endemic taxa that only occurred in two cratons leads us to suggest a geographic connection between those regions during deep time. Combining biogeographic evidence reported from Cambrian studies, this study supports the "missing-link" configuration of Rodinia during the breakup phase. Based on the crinoid global biodiversity pattern updated here, the potential for discovery of new Paleozoic crinoid faunas in China is very high.

  20. Traces of explosive volcanic eruptions in the Upper Ordovician of the Siberian Platform

    Directory of Open Access Journals (Sweden)

    Warren D. Huff

    2014-12-01

    Full Text Available Ordovician K-bentonite beds have a long history of investigation all around the world. They have been reported from Gondwana, the Argentine Precordillera, the Yangtze Platform, Laurentia, Baltica, and numerous terrains between Gondwana and Baltica, which now constitute a part of Europe. In recent years several K-bentonite beds have also been discovered in the Upper Ordovician of the Siberian Platform. This discovery is significant not only for their value in local and regional chronostratigraphic correlation but also for global geochronology, paleogeography, paleotectonic and paleoclimatic reconstructions. All in all, eight individual K-bentonite beds have been identified in the Baksian, Dolborian and Burian regional stages, which correspond roughly to the Upper Sandbian–Katian Global Stages. Zircon crystals from the uppermost K-bentonite bed within the Baksian regional stage provide a 206Pb/238U age of 450.58 ± 0.27 Ma. We will present preliminary results of the study of the three lowermost beds from the Baksian Regional Stage and suggest that the Taconic–Enisej (also spelled Yenisei or Yenisey volcanic arc was continuous along the western margin of Siberia.

  1. 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.

  2. 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 ...

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

    DEFF Research Database (Denmark)

    Rasmussen, Jan Audun Liljeroth; 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...

  4. Occurence of the late Ordovician (Hirnantian) graptolite Normalograptus ojsuensis (Koren & Mikhaylova, 1980) in south-western Sardinia, Italy

    Czech Academy of Sciences Publication Activity Database

    Štorch, Petr; Leone, F.

    2003-01-01

    Roč. 42, 1-2 (2003), s. 31-38 ISSN 0375-7633 R&D Projects: GA AV ČR IAA3013503 Institutional research plan: CEZ:AV0Z3013912 Keywords : Graptolites * Ordovician * Sardinia Subject RIV: DB - Geology ; Mineralogy

  5. Conodont biostratigraphy of the Upper Cambrian and Lower Ordovician of north-western Öland, south-eastern Sweden

    NARCIS (Netherlands)

    Wamel, W.A. van

    1974-01-01

    This paper forms part of the author's thesis "Lithostratigraphy, environmental interpretation and conodont biostratigraphy of the Upper Cambrian and Lower Ordovician of north-western bland, south-eastern Sweden". The purpose of this investigation was to unravel the lithogenesis and the history

  6. Evenness and species abundance in graptolite communities: a new proxy for climate change during the end ordovician mass extinction

    Czech Academy of Sciences Publication Activity Database

    Hawkins, A. D.; Mitchell, C. E.; Sheets, H. D.; Loxton, J.; Belscher, K.; Melchin, M. J.; Finney, S.; Štorch, Petr

    2011-01-01

    Roč. 43, č. 5 (2011), s. 83-83 ISSN 0016-7592. [2011 GSA Annual Meeting and Exposition. 09.10.2011-12.10.2011, Minneapolis] Institutional research plan: CEZ:AV0Z30130516 Keywords : graptolites * Ordovician * climate change Subject RIV: DB - Geology ; Mineralogy http://gsa.confex.com/gsa/2011AM/finalprogram/abstract_196574.htm

  7. Identification of the Paleocene-Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

    NARCIS (Netherlands)

    Frieling, J.|info:eu-repo/dai/nl/338017909; Huurdeman, Emiel; Rem, Charlotte; Donders, T.H.|info:eu-repo/dai/nl/290469872; Pross, Jorg; Bohaty, Steven M.; Holdgate, Guy; Gallagher, Stephen; McGowran, Brian; Bijl, P.K.|info:eu-repo/dai/nl/314028110

    2018-01-01

    Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the

  8. Natural hydraulic fractures and the mechanical stratigraphy of shale-dominated strata

    NARCIS (Netherlands)

    Imber, J.; Armstrong, Howard; Atar, E.; Clancy, Sarah; Daniels, S.; Grattage, J.; Herringshaw, Liam; Trabucho-Alexandre, João; Warren, C.; Wille, J.; Yahaya, L.

    2016-01-01

    The aim of this study is to investigate stratigraphic variations in the spatial distribution and density of natural hydraulic and other fractures within oil mature, shale-dominated strata from the Cleveland Basin, northeast England. The studied interval includes the Pliensbachian Cleveland Ironstone

  9. Aptychi from the Lower Cretaceous strata along the Río Argos (Caravaca, SE Spain)

    NARCIS (Netherlands)

    Vašícek, Z.; Hoedemaeker, Ph.J.

    1997-01-01

    The aptychi of the Berriasian to Barremian strata of the Río Argos succession near Caravaca (SE Spain) are described. One new subspecies is introduced, Lamellaptychus angulocostatus gracilicostatus, from the latest Hauterivian Ohmi Zone (ammonite zone). Like in the Eastern Alps also in Southern

  10. Comparison of phytosociological parameters among three strata of a fragment of ombrophylous mixed forest

    Directory of Open Access Journals (Sweden)

    Sebastião do Amaral Machado

    2013-09-01

    Full Text Available Phytosociological studies based on sampling have been very common in the last 20 years, however, they are rarely carried out using complete enumeration of trees (census. This research compare the phytossociological parameters between three different strata from a remnant of Ombrophylous Mixed Forest (OMF, which are: OMF Montana, Border OMF Montana and OMF Alluvial. The area of 13.71 was topographically divided in blocks of 50 x 50 meters for a better control of the 100% forest inventory (census. All trees with CBH (circumference measured at 1,30 m above ground ≥ 31,5 centimeters were measured, georeferencied, numbered, painted at DBH and identified at species level. In the strata OMF Montana the species with the highest Value of Coverage (VC was Araucaria angustifolia, with 30.6%, followed by Casearia sylvestris with 25.8%. In the Border OMF Montana the species that succeeded Araucaria angustifolia (29.0% was Gochnatia polymorpha with 27.2% of VC. The third strata, OMF Alluvial, presented as predominant species Schinus terebinthifolius (55,5%, followed by Sebastiania commersoniana (27,7%, both characteristics of alluvial environments. In the three strata there was prevalence of secondary pioneer species, proving that the area is in a secondary stage of ecological succession due to past exploratory process.

  11. Oligocene terrestrial strata of northwestern Ethiopia : a preliminary report on paleoenvironments and paleontology

    Science.gov (United States)

    Bonnie F. Jacobs; Neil Tabor; Mulugeta Feseha; Aaron Pan; John Kappelman; Tab Rasmussen; William Sanders; Michael Wiemann; Jeff Crabaugh; Juan Leandro Garcia Massini

    2005-01-01

    The Paleogene record of Afro-Arabia is represented by few fossil localities, most of which are coastal. Here we report sedimentological and paleontological data from continental Oligocene strata in northwestern Ethiopia. These have produced abundant plant fossils and unique assemblages of vertebrates, thus filling a gap in what is known of Paleogene interior Afro-...

  12. Revision of the fossil Echini from the tertiary strata of Java

    NARCIS (Netherlands)

    Martin, K.

    1880-01-01

    In the year 1854 J. A. Herklots published a description of the fossil Echini, which had been found by Junghuhn in the tertiary strata of Java, in the fourth part of a publication, entitled «Fossiles de Java.” I have been occupied in working out the other groups of animals from these deposits, which

  13. 76 FR 69295 - Strata Energy, Inc.; Establishment of Atomic Safety and Licensing Board

    Science.gov (United States)

    2011-11-08

    ..., Inc.; Establishment of Atomic Safety and Licensing Board Pursuant to delegation by the Commission... Atomic Safety and Licensing Board (Board) is being established to preside over the following proceeding... application from Peninsula Minerals, Ltd., doing business as Strata Energy, Inc., requesting a new source and...

  14. Voussoir beam model for lower strong roof strata movement in longwall mining – Case study

    Directory of Open Access Journals (Sweden)

    Chuang Liu

    2017-12-01

    Full Text Available The paper presents the influence of varying immediate roof thickness on the lower strong roof strata movement and failure pattern in longwall coal mining with large mining height. The investigation is based on 58 geological drill holes and hydraulic shield pressure measurements around the longwall Panel 42105 of the Buertai Mine in Inner Mongolia Autonomous Region, China. The longwall Panel 42105 is characterized by relatively soft immediate roof strata of varying thickness superposed by strong strata, herein defined as lower strong roof. A voussoir beam model is adopted to interpret the structural movement of the lower strong roof strata and shield pressure measurements. It is shown that when the immediate roof is relatively thick, the broken overlying lower strong roof tends to form a stable voussoir beam with previously broken layer, thus not exerting high pressure on the hydraulic shield and working face. When the immediate roof is relatively thin, the broken overlying lower strong roof tends to behave as a cantilever beam, thus exerting higher pressure on the hydraulic shield and working face. Comparison of model predictions with measured time-weighted average shield pressure (TWAP shows good agreement.

  15. Assessment of mining horizontal seams at depth considering strata stress factor

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, A.F.

    1983-04-01

    This paper discusses systems of mining level coal seams at large depths in the light of increasing mining depth in the Donbass, where about 50% of mined coal comes from depths exceeding 600 m. Mining systems used in underground mining in the Donbass are evaluated: 77.4% of production is from long pillar mining, 8.6% from longwall mining and 14% from combined systems. Seventeen variants of long pillar mining and longwall mining schemes used in the Donbass are compared. Effects of strata movement and strata control in mine roadways on mining cost are analyzed. A mathematical model is used for comparative evaluations of mining cost at large depths. Analyses show that long pillar mining combined with repeated use of gate roads is associated with considerable cost of support repair and support replacement. Recommendations on support systems suitable for strata control in mine roadways influenced by longwall mining are made. When roof subsidence does not exceed 500 mm, use of three-element yielding arched supports is recommended. In mine roadways with strata subsidence from 500 to 1200 mm, yielding arched supports consisting of five elements should be used. When forecast roof subsidence exceeds 1200 mm, additional support systems (such as friction props or hydraulic props) should be used. (6 refs.) (In Russian)

  16. 76 FR 71082 - Strata Energy, Inc., Ross Uranium Recovery Project; New Source Material License Application...

    Science.gov (United States)

    2011-11-16

    ... NUCLEAR REGULATORY COMMISSION [Docket No. 40-9091; NRC-2011-0148] Strata Energy, Inc., Ross...) submitted an application for a new source material license for the Ross Uranium Recovery Project to be... Leach Uranium Milling Facilities (ISR GEIS) for a new source material license for the Ross Uranium...

  17. Pola Penghidupan Masyarakat di Daerah Perdesaan pada Strata Rumahtangga yang Berbeda

    Directory of Open Access Journals (Sweden)

    Kationo Udin

    2016-10-01

    Full Text Available ABSTRAK Penelitian pola penghidupan di daerah perdesaan perlu dilakukan mengingat daerah perdesaan merupakan bagian integral dari wilayah pembangunan yang perlu mendapat perhatian pemeritah melalui berbagai kebijakan pemberdayaan masyarakat perdesaan dalam konteks pembangunan daerah perdesaan. Untuk itu penelitian ini bertujuan mengkaji (1 strategi penghidupan rumahtangga dan (2 faktor penentu, serta (3 menyusun arahan pengembangan strategi penghidupan yang efektif pada tiap strata ekonomi rumahtangga dalam rangka peningkatan pendapatan di lokasi penelitian. Penelitian ini mengambil lokasi di Desa Karang Jaya Kabupaten Buru dengan unit penelitian pada strata rumahtangga. Metode penelitian yang digunakan adalah metode survey dengan menggunakan kuisioner dan wawancara dalam pengambilan data. Dengan adanya strata rumahtangga maka Teknik sampel menggunakan stratifield random sampling dengan penentuan besar sampel secara proportional. Jumlah sampel strata ekonomi lemah 65 rumahtangga, strata ekonomi menengah 34 rumahtangga dan strata ekonomi kuat 6 rumahtangga. Analisa data dilakukan secara kua ntitatif dengan menggunakan tabel frekuensi dan tabel silang serta dilengkapi dengan indepth interview. Hasil penelitian menunjukkan bahwa strata rumahtangga ekonomi lemah sebagian besar menerapkan strategi pemanfaatan sumberdaya rumahtangga untuk meningkatkan hasil pertanian. Sementara strata rumahtangga ekonomi menengah menerapkan strategi pemanfaatan sumberdaya rumahtangga, diversifikasi pekerjaan dan optimalisasi hasil pertanian. Strata rumahtangga ekonomi kuat lebih fokus pada strategi investasi modal usaha. Adapun yang menjadi faktor penentu dalam penerapan strategi di atas adalah modal fisikal dan modal finansial yang berbeda dari segi dominasi kepemilikan pada tiap strata ekonomi. Untuk itu perlu adanya pengembangan strategi yang lebih efektif melalui peningkatan keahlian/ketrampilan anggota rumahtangga, membentuk kelompok tani/usaha kecil

  18. Evidence for local and global redox conditions at an Early Ordovician (Tremadocian) mass extinction

    Science.gov (United States)

    Edwards, Cole T.; Fike, David A.; Saltzman, Matthew R.; Lu, Wanyi; Lu, Zunli

    2018-01-01

    Profound changes in environmental conditions, particularly atmospheric oxygen levels, are thought to be important drivers of several major biotic events (e.g. mass extinctions and diversifications). The early Paleozoic represents a key interval in the oxygenation of the ocean-atmosphere system and evolution of the biosphere. Global proxies (e.g. carbon (δ13C) and sulfur (δ34S) isotopes) are used to diagnose potential changes in oxygenation and infer causes of environmental change and biotic turnover. The Cambrian-Ordovician contains several trilobite extinctions (some are apparently local, but others are globally correlative) that are attributed to anoxia based on coeval positive δ13C and δ34S excursions. These extinction and excursion events have yet to be coupled with more recently developed proxies thought to be more reflective of local redox conditions in the water column (e.g. I/Ca) to confirm whether these extinctions were associated with oxygen crises over a regional or global scale. Here we examine an Early Ordovician (Tremadocian Stage) extinction event previously interpreted to reflect a continuation of recurrent early Paleozoic anoxic events that expanded into nearshore environments. δ13C, δ34S, and I/Ca trends were measured from three sections in the Great Basin region to test whether I/Ca trends support the notion that anoxia was locally present in the water column along the Laurentian margin. Evidence for anoxia is based on coincident, but not always synchronous, positive δ13C and δ34S excursions (mainly from carbonate-associated sulfate and less so from pyrite data), a 30% extinction of standing generic diversity, and near-zero I/Ca values. Although evidence for local water column anoxia from the I/Ca proxy broadly agrees with intervals of global anoxia inferred from δ13C and δ34S trends, a more complex picture is evident where spatially and temporally variable local trends are superimposed on time-averaged global trends. Stratigraphic

  19. Undergraduates Discovering Folds in ''Flat'' Strata: An Unusual Undergraduate Geology Field Methods Course

    Science.gov (United States)

    Abolins, Mark

    2014-01-01

    Undergraduates learned to measure, map, and interpret bedding plane attitudes during a semesterlong geology field methods course in a field area where strata dip less than 98. Despite the low dip of the strata, 2011 field course students discovered a half-kilometer-wide structural basin by using digital levels and Brunton pocket transits to…

  20. Unraveling the phylogenetic relationships of the Eccoptochilinae, an enigmatic array of ordovician cheirurid trilobites.

    Directory of Open Access Journals (Sweden)

    I Wesley Gapp

    Full Text Available The Cheiruridae are a diverse group of trilobites and several subfamilies within the clade have been the focus of recent phylogenetic studies. This paper focuses on the relationships of one of those subfamilies, the Ordovician Eccoptochilinae. We analyze sixteen species from six genera within the traditionally defined group, using the pilekiid Anacheirurus frederici as an outgroup. To assess the monophyly of the Eccoptochilinae seven sphaerexochine species, Kawina arnoldi, Sphaerexochus arenosus, S. atacius, S. latifrons, S. mirus, S. parvus, and S. scabridus were included in the analysis as well. The results of this analysis show that the genus Eccoptochile represents a paraphyletic grade and species traditionally assigned to Parasphaerexochus and Skelipyx plot within Pseudosphaerexochus. Also, representative species of Sphaerexochinae plot within the traditionally defined Eccoptochilinae, suggesting Eccoptochilinae itself is paraphyletic. To resolve this, we propose all species of Pseudosphaerexochus be placed within Sphaerexochinae and Eccoptochilinae be restricted to a monotypic Eccoptochile clavigera.

  1. 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.

  2. The climatic significance of Late Ordovician-early Silurian black shales

    Science.gov (United States)

    Pohl, A.; Donnadieu, Y.; Le Hir, G.; Ferreira, D.

    2017-04-01

    The Ordovician-Silurian transition (˜455-430 Ma) is characterized by repeated climatic perturbations, concomitant with major changes in the global oceanic redox state best exemplified by the periodic deposition of black shales. The relationship between the climatic evolution and the oceanic redox cycles, however, remains largely debated. Here using an ocean-atmosphere general circulation model accounting for ocean biogeochemistry (MITgcm), we investigate the mechanisms responsible for the burial of organic carbon immediately before, during, and right after the latest Ordovician Hirnantian (445-444 Ma) glacial peak. Our results are compared with recent sedimentological and geochemical data. We show that the late Katian time slice (˜445 Ma), typified by the deposition of black shales at tropical latitudes, represents an unperturbed oceanic state, with regional organic carbon burial driven by the surface primary productivity. During the Hirnantian, our experiments predict a global oxygenation event, in agreement with the disappearance of the black shales in the sedimentary record. This suggests that deep-water burial of organic matter may not be a tenable triggering factor for the positive carbon excursion reported at that time. Our simulations indicate that the perturbation of the ocean circulation induced by the release of freshwater, in the context of the post-Hirnantian deglaciation, does not sustain over sufficiently long geological periods to cause the Rhuddanian (˜444 Ma) oceanic anoxic event. Input of nutrients to the ocean, through increased continental weathering and the leaching of newly exposed glaciogenic sediments, may instead constitute the dominant control on the spread of anoxia in the early Silurian.

  3. Bedrock stability in southeastern Sweden. Evidence from fracturing in the ordovician limestones of northern Oeland

    International Nuclear Information System (INIS)

    Milnes, A.G.; Gee, D.G.

    1992-09-01

    The stability of the bedrock in SE Sweden with regard to radioactive waste disposal has recently been the subject of some controversy. In order to better assess the age and significance of fracturing in the Precambrian basement at the site of the Aespoe Hard Rock Laboratory (HRL), near Oskarshamn, a detailed analysis of fracturing in the lower Ordovician limestones exposed along the west coast of the neighbouring island of Oeland has been carried out. The limestones form continuously exposed shore platforms, in segments up to 30 m broad and several kilometres long. These, and numerous quarries, provide ideal objects for quantitative analysis (ground and air photo mapping, scanline logging), and unique opportunities for investigating the amount of movement on the fractures, because of well-developed bedding and abundant rod-shaped fossils on the bedding surfaces. The fracture patterns are dominated by two sets of subvertical fractures, a NW trending closely spaced and strongly orientated set and a NNE-ENE trending widely spaced and variably orientated set. Only about 10% of the fractures in both sets show lateral fossil displacement, with maximum movement of 5 cm, and only 3% of the fractures show vertical displacement of bedding (maximum 8 cm). All in all, the lower Ordovician limestones along the exposed shoreline have suffered remarkably little deformation since deposition, i.e. over the last 500 million years. Appreciable bedrock instability, if it occurred, must have been concentrated offshore, or in the unexposed segments of the coastline, where some weak indications of slight movement (changes of a few metres in stratigraphic level) have been observed. Among other recommendations for further work, geophysical investigations to test these indications are suggested. (54 refs.)

  4. Black shale source rocks and oil generation in the Cambrian and Ordovician of the central Appalachian Basin, USA

    Science.gov (United States)

    Ryder, R.T.; Burruss, R.C.; Hatch, J.R.

    1998-01-01

    Nearly 600 million bbl of oil (MMBO) and 1 to 1.5 trillion ft3 (tcf) of gas have been produced from Cambrian and Ordovician reservoirs (carbonate and sandstone) in the Ohio part of the Appalachian basin and on adjoining arches in Ohio, Indiana, and Ontario, Canada. Most of the oil and gas is concentrated in the giant Lima-Indiana field on the Findlay and Kankakee arches and in small fields distributed along the Knox unconformity. Based on new geochemical analyses of oils, potential source rocks, bitumen extracts, and previously published geochemical data, we conclude that the oils in both groups of fields originated from Middle and Upper Ordovician blcak shale (Utica and Antes shales) in the Appalachian basin. Moroever, we suggest that approximately 300 MMBO and many trillions of cubic feet of gas in the Lower Silurian Clinton sands of eastern Ohio originated in the same source rocks. Oils from the Cambrian and Ordovician reservoirs have similar saturated hydrocarbon compositions, biomarker distributions, and carbon isotope signatures. Regional variations in the oils are attributed to differences in thermal maturation rather than to differences in source. Total organic carbon content, genetic potential, regional extent, and bitument extract geochemistry identify the balck shale of the Utica and Antes shales as the most plausible source of the oils. Other Cambrian and Ordovician shale and carbonate units, such as the Wells Creek formation, which rests on the Knox unconformity, and the Rome Formation and Conasauga Group in the Rome trough, are considered to be only local petroleum sources. Tmax, CAI, and pyrolysis yields from drill-hole cuttings and core indicate that the Utica Shale in eastern and central Ohio is mature with respect to oil generation. Burial, thermal, and hydrocarbon-generation history models suggest that much of the oil was generated from the Utica-Antes source in the late Paleozoic during the Alleghanian orogeny. A pervasive fracture network

  5. Depositional environments, provenance and paleoclimatic implications of Ordovician siliciclastic rocks of the Thango Formation, Spiti Valley, Tethys Himalaya, northern India

    Science.gov (United States)

    Rashid, Shaik A.; Ganai, Javid A.

    2018-05-01

    Recently published findings indicate that the Ordovician period has been much more dynamic than previously anticipated thus making this period significant in geological time. The Ordovician of India can best be studied in the Spiti region because the Spiti basin records the complete uninterrupted history of excellent marine sedimentary rocks starting from Cambrian to Paleogene which were deposited along the northern margin of India. Due to these reasons the geochemical data on the Ordovician rocks from the Spiti region is uncommon. The present geochemical study on the Ordovician Thango Formation (Sanugba Group) is mainly aimed to understand the provenance and the paleoclimatic conditions. The sandstones are the dominant lithology of the Thango Formation with intercalations of minor amount of shales. Detailed petrographic and sedimentological analysis of these rocks suggest that three major depositional environments, viz., fluvial, transitional and marine prevailed in the basin representing transgressive and regressive phases. The major and trace element ratios such as SiO2/Al2O3, K2O/Na2O and La-Th- Sc discrimination diagram suggest that these rocks were deposited in passive margin tectonic settings. Various geochemical discriminants and elemental ratios such as K2O/Na2O, Al2O3/TiO2, La/Sc, Th/Sc, Cr/Th, Zr/Sc, (Gd/Yb)N and pronounced negative Eu anomalies indicate the rocks to be the product of weathering of post-Archean granites. The striking similarities of the multi-elemental spider diagrams of the studied sediments and the Himalayan granitoids indicate that sediments are sourced from the Proterozoic orogenic belts of the Himalayan region. Chemical index of alteration (CIA) values of the studied sediments (55-72) suggest that the source rocks underwent low to moderate degree of chemical weathering. The span of the CIA values (55-72) recorded in the sediments from the Spiti region may have resulted from varying degrees of weathering conditions in the source area

  6. Investigation of deep permeable strata in the permian basin for future geothermal energy reserves

    Energy Technology Data Exchange (ETDEWEB)

    Erdlac, Richard J., Jr.; Swift, Douglas B.

    1999-09-23

    This project will investigate a previously unidentified geothermal energy resource, opening broad new frontiers to geothermal development. Data collected by industry during oil and gas development demonstrate deep permeable strata with temperatures {ge} 150 C, within the optimum window for binary power plant operation. The project will delineate Deep Permeable Strata Geothermal Energy (DPSGE) assets in the Permian Basin of western Texas and southeastern New Mexico. Presently, geothermal electrical power generation is limited to proximity to shallow, high-temperature igneous heat sources. This geographically restricts geothermal development. Delineation of a new, less geographically constrained geothermal energy source will stimulate geothermal development, increasing available clean, renewable world energy reserves. This proposal will stimulate geothermal reservoir exploration by identifying untapped and unrealized reservoirs of geothermal energy. DPSGE is present in many regions of the United States not presently considered as geothermally prospective. Development of this new energy source will promote geothermal use throughout the nation.

  7. Study on Strata Behavior Regularity of 1301 Face in Thick Bedrock of Wei - qiang Coal Mine

    Science.gov (United States)

    Gu, Shuancheng; Yao, Boyu

    2017-09-01

    In order to ensure the safe and efficient production of the thick bedrock face, the rule of the strata behavior of the thick bedrock face is discussed through the observation of the strata pressure of the 1301 first mining face in Wei qiang coal mine. The initial face is to press the average distance of 50.75m, the periodic weighting is to press the average distance of 12.1m; during the normal mining period, although the upper roof can not be broken at the same time, but the pressure step is basically the same; the working face for the first weighting and periodical weighting is more obvious to the change of pressure step change, when the pressure of the working face is coming, the stent force increased significantly, but there are still part of the stent work resistance exceeds the rated working resistance, low stability, still need to strengthen management.

  8. Leisure, consumption and sport between the upper strata: Contributions to the development of a problematic field

    Directory of Open Access Journals (Sweden)

    Rodolfo Iuliano

    2010-11-01

    Full Text Available The purpose of this article is to deal with various problems concerned with the social productivity of the spaces and practices of leisure, consumption and sport, particularly referring to the upper strata and their sociability. Following this approach, we develop a critical work on the main perspectives on leisure and consumption, emphasizing, in some cases, the underlying normative assumptions and, in others, the conceptual contributions related to the positivity of leisure and consumption as elements for structuring social categories. Finally, the article analyses the contributions of the sociology and anthropology of sport to the study of the relationship between sporting practices and social levels, arguing in favour of giving a higher hierarchy to the study of phenomenon related to sport, leisure and consumption as legitimate fields of research of the transformations in the social structure, especially, connected to the upper strata

  9. The Strata-1 Regolith Dynamics Experiment: Class 1E Science on ISS

    Science.gov (United States)

    Fries, Marc; Graham, Lee; John, Kristen

    2016-01-01

    The Strata-1 experiment studies the evolution of small body regolith through long-duration exposure of simulant materials to the microgravity environment on the International Space Station (ISS). This study will record segregation and mechanical dynamics of regolith simulants in a microgravity and vibration environment similar to that experienced by regolith on small Solar System bodies. Strata-1 will help us understand regolith dynamics and will inform design and procedures for landing and setting anchors, safely sampling and moving material on asteroidal surfaces, processing large volumes of material for in situ resource utilization (ISRU) purposes, and, in general, predicting the behavior of large and small particles on disturbed asteroid surfaces. This experiment is providing new insights into small body surface evolution.

  10. Sedimentary basin analysis and petroleum potential of the Cretaceous and Tertiary strata in Korea.

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jin-Dam; Kwak, Young-Hoon; Bong, Pil-Yoon [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    Since 1992 sedimentary basin analysis to assess petroleum potential of the Cretaceous and Tertiary strata in the Korean onshore and continental shelf have been carried out. The Cretaceous non-marine strata mainly occupy the Gyeongsang Basin in southeastern part of the Korean Peninsula and small basins such as Haenam and Gyeokpo depressions in western coastal areas. The Tertiary strata are mostly distributed in Domi, Cheju, Socotra subbasins, and Okinawa Trough in the South Continental Shelf, and Kunsan and Heuksan basins in the West. The basin evolution and petroleum potential for each basins are characterized as follow. The Cretaceous Gyeongsang sediments were deposited in three subbasins including Milyang, Euisung and Yongyang subbasins. The black shales in Nakdong and Jinju formations are interpreted to contain abundant organic matter during the deposition, thermal maturity reaching up to the zone of dry gas formation. Because porosity and permeability are too low, the sandstones can act as a tight gas reservoir rather than conventional oil and gas reservoir. The latest Cretaceous strata of Haenam and Kyeokpo depressions in western coastal area are correlated into the Yuchon Volcanic Group of the Gyeongsang Basin. Petroleum potential of the Early Cretaceous basin in the West Continental Shelf could be relatively high in terms of sedimentary basin filled with thick lacustrine sediments. The Kunsan basin in the West Continental Shelf originated in the Early Cretaceous time expanded during the Paleocene time followed by regional erosion at the end of Paleocene on which Neogene sediment have been accumulated. The Paleocene-Eocene sublacustrine shales may play an major role as a source and cap rocks. South Continental Shelf Basin is subdivided by Cheju subbasin in the center, Socotra Subbasin to the west, Domi Subbasin to the northeast and Okinawa Trough to the East. The potential hydrocarbon traps associated with anticline, titled fault blocks, fault, unconformity

  11. Preliminary numerical simulation for shallow strata stability of coral reef in South China Sea

    Science.gov (United States)

    Tang, Qinqin; Zhan, Wenhuan; Zhang, Jinchang

    2017-04-01

    Coral reefs are the geologic material and special rock and soil, which live in shallow water of the tropic ocean and are formed through biological and geological action. Since infrastructure construction is being increasingly developed on coral reefs during recent years, it is necessary to evaluate the shallow strata stability of coral reefs in the South China Sea. The paper is to study the borehole profiles for shallow strata of coral reefs in the South China Sea, especially in the hydrodynamic marine environment?, and to establish a geological model for numerical simulation with Geo-Studio software. Five drilling holes show a six-layer shallow structure of South China Sea, including filling layer, mid-coarse sand, coral sand gravel, fine sand, limestone debris and reef limestone. The shallow coral reef profile next to lagoon is similar to "layers cake", in which the right side close to the sea is analogous to "block cake". The simulation results show that coral reef stability depends on wave loads and earthquake strength, as well as the physical properties of coral reefs themselves. The safety factor of the outer reef is greater than 10.0 in the static condition, indicating that outer reefs are less affected by the wave and earthquake. However, the safety factor next to lagoon is ranging from 0.1 to 4.9. The main reason for the variations that the strata of coral reefs close to the sea are thick. For example, the thickness of reef limestone is more than 10 m and equivalent to the block. When the thickness of inside strata is less than 10 m, they show weak engineering geological characteristics. These findings can provide useful information for coral reef constructions in future. This work was funded by National Basic Research Program of China (contract: 2013CB956104) and National Natural Science Foundation of China (contract: 41376063).

  12. SamplingStrata: An R Package for the Optimization of Strati?ed Sampling

    Directory of Open Access Journals (Sweden)

    Giulio Barcaroli

    2014-11-01

    Full Text Available When designing a sampling survey, usually constraints are set on the desired precision levels regarding one or more target estimates (the Ys. If a sampling frame is available, containing auxiliary information related to each unit (the Xs, it is possible to adopt a stratified sample design. For any given strati?cation of the frame, in the multivariate case it is possible to solve the problem of the best allocation of units in strata, by minimizing a cost function sub ject to precision constraints (or, conversely, by maximizing the precision of the estimates under a given budget. The problem is to determine the best stratification in the frame, i.e., the one that ensures the overall minimal cost of the sample necessary to satisfy precision constraints. The Xs can be categorical or continuous; continuous ones can be transformed into categorical ones. The most detailed strati?cation is given by the Cartesian product of the Xs (the atomic strata. A way to determine the best stratification is to explore exhaustively the set of all possible partitions derivable by the set of atomic strata, evaluating each one by calculating the corresponding cost in terms of the sample required to satisfy precision constraints. This is una?ordable in practical situations, where the dimension of the space of the partitions can be very high. Another possible way is to explore the space of partitions with an algorithm that is particularly suitable in such situations: the genetic algorithm. The R package SamplingStrata, based on the use of a genetic algorithm, allows to determine the best strati?cation for a population frame, i.e., the one that ensures the minimum sample cost necessary to satisfy precision constraints, in a multivariate and multi-domain case.

  13. Mass and nutritional quality of upper and lower strata of tropical forages

    Directory of Open Access Journals (Sweden)

    Mailson Poczynek

    2016-09-01

    Full Text Available The goal of this work was to evaluate the growth dynamics and chemical characteristics of the upper and lower strata of summer perennial grasses under a four cuts system. The experiment was conducted in a randomized block design, composed of 28 treatments in a factorial arrangement of 7x4, with four repetitions. The cultivars evaluated were Star Grass, Coast-cross, Tifton 68, Tifton 85, Jiggs, Roxinha and Quicuio. Each cultivar was cut when it reached 95% light interception. The cultivars Jiggs and Tifton 68 had the highest (P < 0.05 accumulation of dry biomass ha-1 during the four cuts, with productions of 21,348 and 21,016 kg ha-1, respectively. The ash content varied (P < 0.05 among species and times of cutting for both strata. Cellulose contents were significantly different in the upper stratum, with the highest concentrations found in cvs. Quicuio and Tifton 68 (39.12% and 38.07%, respectively. We found the highest levels of lignin (P < 0.05, for both strata, in cv. Quicuio. Cultivars Jiggs and Tifton 68 were the most appropriate for a management system of four cuts, displaying good chemical composition and high productivity.

  14. Numerical Modeling of Mechanical Behavior for Buried Steel Pipelines Crossing Subsidence Strata.

    Science.gov (United States)

    Zhang, J; Liang, Z; Han, C J

    2015-01-01

    This paper addresses the mechanical behavior of buried steel pipeline crossing subsidence strata. The investigation is based on numerical simulation of the nonlinear response of the pipeline-soil system through finite element method, considering large strain and displacement, inelastic material behavior of buried pipeline and the surrounding soil, as well as contact and friction on the pipeline-soil interface. Effects of key parameters on the mechanical behavior of buried pipeline were investigated, such as strata subsidence, diameter-thickness ratio, buried depth, internal pressure, friction coefficient and soil properties. The results show that the maximum strain appears on the outer transition subsidence section of the pipeline, and its cross section is concave shaped. With the increasing of strata subsidence and diameter-thickness ratio, the out of roundness, longitudinal strain and equivalent plastic strain increase gradually. With the buried depth increasing, the deflection, out of roundness and strain of the pipeline decrease. Internal pressure and friction coefficient have little effect on the deflection of buried pipeline. Out of roundness is reduced and the strain is increased gradually with the increasing of internal pressure. The physical properties of soil have a great influence on the mechanical properties of buried pipeline. The results from the present study can be used for the development of optimization design and preventive maintenance for buried steel pipelines.

  15. Tectonic subsidence analyses of miogeoclinal strata from mesozoic marginal basin of Peru

    Energy Technology Data Exchange (ETDEWEB)

    Devlin, W.J.

    1988-01-01

    The Western Peruvian trough is composed of an eastern miogeoclinical facies of carbonate and clastic strata, and a western eugeoclinal facies consisting of a succession of volcanic and sedimentary rocks. In norther and central Peru, the miogeocline is located between a tectonic hinge adjacent to platformal facies of the Maranon geanticline on the east, and an outer marginal high bounded by the Cordillera Blanca fault and Tapacocha axis on the west. Miogeoclinal and platformal strata in southern Peru occur in a broad belt between Arequipa and Lago Titicaca. A marginal basin setting has been proposed for the Western Peruvian trough and the several kilometers of subsidence in the basin has been attributed to back-arc extension and crustal thinning. As a test of this model, quantitative tectonic subsidence curves were constructed from representative sections within miogeoclinar strata from four localities. Preliminary results indicate that the calculated curves have the same overall form as the age-depth curve for ocean floor, suggesting that subsidence was controlled by cooling and thermal contraction of heated lithosphere. The slopes of the curves are less than those for subsidence of oceanic lithosphere. However, they are in agreement with geologic evidence that the miogeocline accumulated on continental crust. Significant variations in the timing of onset, duration, and magnitude of subsidence are observed between sections from northern and southern Peru.

  16. Numerical Modeling of Mechanical Behavior for Buried Steel Pipelines Crossing Subsidence Strata.

    Directory of Open Access Journals (Sweden)

    J Zhang

    Full Text Available This paper addresses the mechanical behavior of buried steel pipeline crossing subsidence strata. The investigation is based on numerical simulation of the nonlinear response of the pipeline-soil system through finite element method, considering large strain and displacement, inelastic material behavior of buried pipeline and the surrounding soil, as well as contact and friction on the pipeline-soil interface. Effects of key parameters on the mechanical behavior of buried pipeline were investigated, such as strata subsidence, diameter-thickness ratio, buried depth, internal pressure, friction coefficient and soil properties. The results show that the maximum strain appears on the outer transition subsidence section of the pipeline, and its cross section is concave shaped. With the increasing of strata subsidence and diameter-thickness ratio, the out of roundness, longitudinal strain and equivalent plastic strain increase gradually. With the buried depth increasing, the deflection, out of roundness and strain of the pipeline decrease. Internal pressure and friction coefficient have little effect on the deflection of buried pipeline. Out of roundness is reduced and the strain is increased gradually with the increasing of internal pressure. The physical properties of soil have a great influence on the mechanical properties of buried pipeline. The results from the present study can be used for the development of optimization design and preventive maintenance for buried steel pipelines.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    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 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...

  18. 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.

  19. Investigation of the age and geological thermal history of the strata containing dinosaurs fossil in Tianzhen county of Shanxi Province

    International Nuclear Information System (INIS)

    Kang Tiesheng; Wang Lanfen; Wang Shicheng; Cheng Zhengwu

    1996-01-01

    The age and thermal history of the strata containing dinosaurs fossil in Tianzhen County of Shanxi Province have been studied using apatite and zircon fission track analysis. It is shown that the burial age of dinosaurs skeletons is not earlier than Late Cretaceous. The provenance area of the strata had experienced heating events with temperature higher than 200-250 degree C 73 Ma ago. But the strata has been at environmental temperature and never been affected by heating events since the dinosaurs skeletons were buried

  20. Latest Ordovician-earliest Silurian acritarchs and chitinozoans from subsurface samples in Jebel Asba, Kufra Basin, SE Libya

    OpenAIRE

    Thusu , Bindra; Rasul , Sayed; Paris , Florentin; Meinhold , Guido; Howard , James ,; Abutarruma , Youssef; Whitham , Andrew ,

    2013-01-01

    International audience; Latest Ordovician-earliest Silurian Tanezzuft Formation shales recovered from core material of the shallow borehole JA-2 drilled in Jebel Asba at the eastern margin of the Kufra Basin, southeastern Libya, yielded well-diversified palynomorph assemblages with transparent and brownish to yellowish vesicles and organic matter (visual kerogen Types 1 and 2) from depth interval 46.20 to 67.82 m. In addition, miospores including cryptospores, and Tasmanites sp. ("Tasmanites ...

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

    OpenAIRE

    Kristian G. Jakobsen; Glenn A. Brock; Arne T. Nielsen

    2016-01-01

    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...

  2. 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

    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 Province of the Western United States to establish the environmental context for the Ordovician gastropod radiation. Gastropods are present within every facies examined, but their relative abundance and distribution varies. Gastropods are rare in normal marine settings and abundant in harsh (i.e., dysoxic, hypersaline) environments. Their environmental context is shown to impact survivorship through the end-Ordovician extinction event and throughout the Paleozoic and Mesozoic. Collecting accurate density data for fossil deposits can prove challenging, especially when beds are not exposed in plane view. In these cases, paleontologists are tasked with reconstructing shellbed density from cross section exposure. This study presents a mathematical model to calculate the density of fossil material within a bed from bedding cross section counts. The model is calibrated against an Ordovician biofacies comprised of oncoids, macluritid gastropods and receptaculitids exposed in the Arrow Canyon Range of Southern Nevada, where unique preservation provides both cross section exposures and plan view of fossil concentrations. University Earth Science Departments seeking to establish impactful geoscience outreach programs often pursue large-scale, grant funded programs. While this type of outreach is highly successful, it is also extremely costly, and grant funding can be difficult to secure. Here, we present the Geoscience Education Outreach Program (GEOP), a small-scale, very affordable model tested over five years in the Department of Earth Sciences at UCR. GEOP provides a variety of outreach events and allows UCR Earth Sciences to

  3. The Ordovician magmatic arc in the northern Chile-Argentina Andes between 21° and 26° south latitude

    Science.gov (United States)

    Niemeyer, Hans; Götze, Jens; Sanhueza, Marcos; Portilla, Carolina

    2018-01-01

    A continental magmatic arc (the Famatinian magmatic arc) was developed on the western margin of Gondwana during the Early to Middle Ordovician. This has a northwestern orientation in the northern Chile-Argentina Andes between 21° and 26° south latitude with a northeastern directed subduction zone and developed on a continental crust represented by a metamorphic basement. A paleogeographical scheme for the Ordovician magmatic arc is proposed and two tectonic environments can be recognized from our own data and data from the literature: forearc and arc. The Cordón de Lila Complex can be assigned to a forearc position. Here the turbiditic flows become paralell to the northwestern elongation of the magmatic arc. The sedimentation in the frontal-arc high platform of the forearc is represented by stromatolitic limestones and a zone of phosphate production. The internal structure of the arc can be inferred from the petrographic composition of the turbidites: basaltic and andesitic lavas, dacitic and/or rhyolitic lavas and ash fall tuffs. Also the Quebrada Grande Formation was developed on the forearc. Plutonic Ordovician rocks testify the continuity of the magmatic arc. The data about the basement exposed in the present paper do not support the existence of the Arequipa-Antofalla Terrane.

  4. Ordovician graptolites from the basal part of the Palaeozoic transgressive sequence in the Karadere area, Zonguldak Terrane, NW Turkey

    Directory of Open Access Journals (Sweden)

    M. Cemal Göncüoglu

    2014-12-01

    Full Text Available The Karadere area to the east of Safranbolu in NW Anatolia is one of the very few localities in Turkey where the contact between the Cadomian basement and the Lower Palaeozoic transgressive succession is well exposed. The Ordovician graptolite Rhabdinopora flabelliformis (Eichwald ssp. was found in the basal part of the Bakacak Formation, indicating an Early to early Late Tremadocian age for the beginning of the Palaeozoic transgression in the Zonguldak terrane. A few metres above this occurrence, another horizon contains Paradelograptus cf. antiquus (T. S. Hall, which mainly ranges into the Late Tremadocian. Higher up in the Ordovician succession, a new graptolite bed confirms an early Darriwilian (Dw1 age for the middle part of the Karadere Formation with the occurrence of the biozonal index Levisograptus austrodentatus (Harris & Keble and the first record of Tetragraptus cor (Strandmark in the area. The palaeobiogeographic distribution of these Karadere fossils is in agreement with a peri-Gondwanan affinity of the Zonguldak Terrane of the Pontides, NW Anatolia, during the Early–Middle Ordovician.

  5. A subaqueous welded tuff from the Ordovician of County Waterford, Ireland

    Science.gov (United States)

    Fritz, William J.; Stillman, Chris J.

    1996-01-01

    The Metal Man Tuff (MMT) from the Ordovician of County Waterford, Ireland was emplaced and welded in water depths greater than the thickness of the pyroclastic flow. The MMT is the basal member of the Middle Tramore Volcanic Formation (MTVF) of the 5-km-thick Tramore Group. The MMT consists of a 10-m-thick basal graded zone that represents a pyroclastic flow consisting of angular clasts of black mudstone, pumice, gray flow banded rhyolite, and pink massive rhyolite set in a matrix of non-deformed ash shards and pumice. Maximum grain size grades from large cobbles and small boulders to pebbles. The basal 10-30 cm is depleted with respect to the largest boulders resulting in an inversely graded basal layer. The basal graded zone passes upward into a transition zone with a strong eutaxitic foliation defined by elongated fiamme of mudstone and flattened pumice. Overlying this is an upper welded zone with a pronounced eutaxitic foliation, columnar jointing, flattened ash shards and shards deformed around phenocrysts and spheroids. The presence of these features indicate that the deposit is welded, was hot, and was in motion as the shards deformed. The MMT represents a pyroclastic flow that was a hot primary product of an eruption rather than re-mobilized cold pyroclastic debris. The MMT is bounded by suspension deposited fine-grained tuff, tuffaceous mudstone and terrigenous mudstone deposited below storm wave base. Many of the mudstone horizons contain brachipod faunas from shelf-depth water. Nowhere in the 5-km-thick Tramore Group is there terrigenous sandstone, evidence of unidirectional flowing water, nor any indication of shoreline, alluvial environments, or subaerial exposure. It thus seems reasonable to conclude that the MMT was emplaced and welded subaqueously. The geochemistry of the MMT is typical of other high-silica (70-78 wt.% SiO 2) rhyolite from the Ordovician of Ireland. The chemistry of the MMT is consistent from top to bottom allowing it to be

  6. Early Devonian polygnathids of Northeast Asia and correlation of Pragian/Emsian strata of the marginal seas of Angarida

    Czech Academy of Sciences Publication Activity Database

    Baranov, V.; Slavík, Ladislav; Blodgett, R. B.

    2014-01-01

    Roč. 89, č. 3 (2014), s. 645-678 ISSN 1214-1119 Institutional support: RVO:67985831 Keywords : Early Devonian * Pragian/Emsian strata * Angarida Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.515, year: 2014

  7. Feasibility of high-helium natural gas exploration in the Presinian strata, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Jian Zhang

    2015-01-01

    Full Text Available Helium in China highly depends on import at present, so the most practical way to change the situation is searching for medium-to-large natural gas fields with high helium content. Therefore, the hydrocarbon accumulation mechanism and the helium origin of the Weiyuan high-helium natural gas reservoir have been analyzed to find out the feasibility of finding natural gas field with high helium content in the Presinian strata of the Sichuan Basin. Based on twelve outcrop sections and drilling data of four wells encountering the Presinian strata, the petrological features, sedimentary facies and source rocks of Presinian strata were systematically analyzed, which shows that the sedimentary formation developed in the Presinian is the Nanhua system, and the stratigraphic sequence revealed by outcrop section in the eastern margin includes the Nantuo, Datangpo, Gucheng and Liantuo Fms, and it is inferred that the same stratigraphic sequence may occur inside the basin. The Nantuo, Gucheng and Liantuo Fms are mainly glacial deposits of glutenite interbedded with mudstone; the Datangpo Fm is interglacial deposits of sandstone and shale, the lower part shale, rich in organic matter, is fairly good source rock. Further study showed that the Nantuo coarse-grained clastic reservoir, Datangpo source rock and the intruded granite “helium source rock” make up a good high-helium gas system. Controlled by the early rift, the thick Presinian sedimentary rocks occur primarily inside the rift. The distribution of sedimentary rocks and granite in the basin was predicted by use of the seismic data, which shows that the feasibility of finding high-helium gas reservoirs in Ziyang area of the Sichuan Basin is great.

  8. 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.

  9. LOWER TO MIDDLE ORDOVICIAN ACRITARCHS AND CHITINOZOANS FROM NORTHERN KARAKORUM MOUNTAINS, PAKISTAN

    Directory of Open Access Journals (Sweden)

    MARCO QUINTAVALLE

    2000-03-01

    Full Text Available The lower Vidiakot section (Chitral, Pakistan comprises the lower part (Yarkhun Formation and the base of the Vidiakot Formation of the terrigenous complex transgressively overlying the crystalline basement of Northern Karakorum. From this section, 8 of 15 samples contain moderately abundant and poorly preserved acritarchs and rare, badly preserved chitinozoans. Three different palynological assemblages have been distinguished which are referable to the chronological interval early Arenig-earliest Llanvirn. The presence of Arbusculidium, Coryphidium, and Striatotheca in most samples confirms the paleogeographic attribution of the Northern Karakorum Terrane to the northern Gondwana margin (Lower to Middle Ordovician Mediterranean acritarch Palaeoprovince. Refined correlation with other areas and with the previously studied Ishkarwaz section (upper Yarkhun Valley, Chitral enables the authors the Yarkun Formation to be dated as early Arenig (British lower nitidus graptolite Zone to latest Arenig (uppermost graptolite hirundo Zone. The base of the overlying Vidiakot Formation is here correlated with the uppermost hirundo- lowermost artus graptolite Zones (latest Arenig-earliest Llanvirn. 

  10. 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.

  11. 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.

  12. 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.

  13. An Upper Ordovician sponge-bearing micritic limestone and implication for early Palaeozoic carbonate successions

    Science.gov (United States)

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

    2015-04-01

    A potentially new type of non-reef sponge-bearing micritic limestone is reported from the Upper Ordovician Xiazhen Formation of south-eastern China. The sponges are preserved as incomplete skeletons that consist of curved bifurcated and trifurcated spicules embedded in dark micrite, and can only be recognized under a petrographic microscope. The characteristics of the spicule networks suggest that the sponges are probably belonging to demosponges. However, based on the absence of features such as desma, zygome, a distinct dermal layer, and a canal system, they are not considered to be lithistids. The majority of the sponges are found in a lime mudstone facies, together with some micritic portions of wackestone to grainstone facies, comprising approximately 13% of the 50-m thick micritic limestone successions. It is interpreted that the non-lithistid demosponges flourished on soft substrates over shallow marine carbonate platform. Such sponge-bearing carbonates are similar to spiculites and spongolites in terms of being a major constituent of the sedimentary rocks and their potential contribution as sediment producers, but affinity and modes of preservation of the Xiazhen sponges are significantly different to those of the spiculites and spongolites. In light of the present finding, it is suggested that non-lithistid demosponges may have been more widespread in early Palaeozoic non-reef carbonates than has previously been recognized, thus indicating the critical need for further detailed studies if we are to understand their distributions and sedimentological contributions.

  14. CFD Simulation of Temperature Variation in Carboniferous Rock Strata During UCG

    Directory of Open Access Journals (Sweden)

    Tomasz Janoszek

    2013-01-01

    Full Text Available The numerical simulation was based on the computational fluid dynamics formalism in order to identify the change of temperature in rock strata during underground coal gasification (UCG. The calculations simulated the coal gasification process using oxygen and water vapour as a gasification agent in 120 hours. Based on the selected software (Ansys-Fluent a model of underground coal gasification (UCG process was developed. The flow of the gasification agent, the description of the turbulence model, the heat-exchange model and the method of simulation of chemical reactions of gasification are presented herein.

  15. The geology and palynology of lower and Middle Pennsylvanian strata in the Western Kentucky Coal Field

    Science.gov (United States)

    Eble, C.F.; Greb, S.F.; Williams, D.A.

    2001-01-01

    The Western Kentucky Coal Field is the southern tip of the Eastern Interior, or Illinois Basin. Pennsylvanian rocks in this area, which include conglomerate, sandstone, shale, limestone and coal, were deposited primarily in coastal-deltaic settings at a time when western Kentucky was located close to the equator. This paper discusses temporal changes in regional sedimentation patterns and coal-forming floras of Lower and Middle Pennsylvanian strata in the Western Kentucky Coal Field. Lower Pennsylvanian strata of the Caseyville Formation are characterized by paleovalley-filling sedimentation patterns and extabasinal quartz pebbles. Caseyville Formation coals are characterized thin and discontinuous and were strongly influenced by subsidence within underlying paleovalleys, and the dissected lower Pennsylvanian paleotopography. Caseyville coals are commonly dominated by Lycospora, but can also have variable palynofloras, which probably reflects variable edaphic conditions and edge effects within small, patchy paleomires. Tradewater Formation strata show increased marine influences and tidal-estuarine sedimentation, especially in the middle and upper parts. Coal beds in the lower part of the Tradewater typically are thin and discontinuous, although some economically important beds are present. Coals become thicker, more abundant and more laterally persistent towards the top of the formation. Palynologically, lower and middle Tradewater Formation coals are dominated by Lycospora, but begin to show increased amounts of tree fern spores. Middle and upper Tradewater coals are thicker and more continuous, and contain high percentages of tree fern spores. In addition, cordaite pollen is locally abundant in this interval. Carbondale and Shelburn (Desmoinesian) strata are much more laterally continuous, and occur within classic cyclothems that can be traced across the coal field. Cyclothems have long been interpreted as being eustatically driven, and glacio-eustacy controlled

  16. Environment of deposition and stratigraphy of the uranium-bearing strata around Beaufort West, South Africa

    International Nuclear Information System (INIS)

    Horowitz, A.

    1976-04-01

    Palynological analyses of some 50 samples collected from uranium-bearing strata - as well as the layers immediately above and below them - around Beaufort West, South Africa, indicate that these sediments were laid down in a wide, rather shallow delta in Late Permian times. Most of the sediments are fluvio-deltaic, and most of the plant remains were transported from the north, the hinterland in those times. A considerable percentage of the microfossils, e.g. Veryhachium and hystrichospheres, are clearly from a marine environment. The occurrence of marine microfossils in the spectrum, as compared with those of terrestrial provenance, increases considerably southwards [af

  17. Probiotics prevent growth deficit of colon wall strata of malnourished rats post-lactation.

    Science.gov (United States)

    Lima, Dirlene P; Azevedo, Jorge F de; Hermes-Uliana, Catchia; Alves, Gilberto; Sant'ana, Débora M G; Araújo, Eduardo J A

    2012-09-01

    The objective of this study was to analyze morphometrically the colon wall strata of malnourished rats supplemented with probiotics. Sixteen recently weaned Wistar rats (Rattus norvegicus) were distributed into four groups: animals that received commercial chow (G1, n = 4); animals that received the same feed as G1 and were supplemented with probiotics (G2, n = 4); animals that received chow with 4% of proteins (G3, n = 4); animals that received the same feed as G3 and were supplemented with probiotics (G4, n = 4). After 12 weeks, the proximal colon was collected and submitted to histological processing. Three-µm cuts were stained with H.E., Periodic Acid Schifff (P.A.S.) + diasthasis solution and Alcian Blue (A.B.) pH 2.5 and pH 1.0. The morphometric analysis of the intestinal wall showed that the supplementation with ABT-4 probiotic culture prevents the growth deficit of colon wall strata that normally occurs in malnourished rats right after lactation. Besides, no alteration was observed in the proportion of the number of globet cells in relation to the number of enterocytes in malnourished rats, regardless of the supplementation with probiotics.

  18. Characterisation of inactivation domains and evolutionary strata in human X chromosome through Markov segmentation.

    Directory of Open Access Journals (Sweden)

    Ashwin Kelkar

    2009-11-01

    Full Text Available Markov segmentation is a method of identifying compositionally different subsequences in a given symbolic sequence. We have applied this technique to the DNA sequence of the human X chromosome to analyze its compositional structure. The human X chromosome is known to have acquired DNA through distinct evolutionary events and is believed to be composed of five evolutionary strata. In addition, in female mammals all copies of X chromosome in excess of one are transcriptionally inactivated. The location of a gene is correlated with its ability to undergo inactivation, but correlations between evolutionary strata and inactivation domains are less clear. Our analysis provides an accurate estimate of the location of stratum boundaries and gives a high-resolution map of compositionally different regions on the X chromosome. This leads to the identification of a novel stratum, as well as segments wherein a group of genes either undergo inactivation or escape inactivation in toto. We identify oligomers that appear to be unique to inactivation domains alone.

  19. Astrochronologic Testing in Deep-Time Strata: Historical Overview and Recent Advances

    Science.gov (United States)

    Meyers, S. R.

    2014-12-01

    The quest for astronomical-climate rhythms ("Milankovitch cycles") in Phanerozoic strata is now commonplace, and has yielded fundamental advancements in our understanding of climate change, paleoceanography, astrodynamics, geochronology and chronostratigraphy. Of central importance to this success has been the development of astrochronologic testing methods for the evaluation of astronomical-climate influence on sedimentation; this can be especially challenging for deep-time strata that lack sufficient independent time control (e.g., radioisotopic data) to unambiguously calibrate observed spatial rhythms to temporal periods. Most deep-time (pre-Pleistocene) astrochronologic testing methods fall into one of two categories: (1) those that test for expected amplitude or frequency modulation imposed by an astronomical signal, or (2) those that test for bedding hierarchies ("frequency ratios") that are predicted by the dominant astronomical periods. In this talk, I discuss the historical context of these methods, recent advances that overcome subjective evaluation and circular reasoning, and their implementation in a new "open source" software package for astrochronology (Meyers, 2014, astrochron: An R Package for Astrochronology).

  20. Paleozoic strata of the Dyckman Mountain area, northeastern Medfra quadrangle, Alaska

    Science.gov (United States)

    Dumoulin, Julie A.; Bradley, Dwight C.; Harris, Anita G.

    2000-01-01

    Paleozoic rocks in the Dyckman Mountain area (northeastern Medfra quadrangle; Farewell terrane) include both shallowand deep-water lithologies deposited on and adjacent to a carbonate platform. Shallow-water strata, which were recognized by earlier workers but not previously studied in detail, consist of algal-laminated micrite and skeletal-peloidal wackestone, packstone, and lesser grainstone. These rocks are, at least in part, of Early and (or) Middle Devonian age but locally could be as old as Silurian; they accumulated in shallow subtidal to intertidal settings with periodically restricted water circulation. Deepwater facies, reported here for the first time, are thin, locally graded beds of micrite and calcisiltite and subordinate thick to massive beds of lime grainstone and conglomerate. Conodonts indicate an age of Silurian to Middle Devonian; the most tightly dated intervals are early Late Silurian (early to middle Ludlow). These strata formed as hemipelagic deposits, turbidites, and debris flows derived from shallow-water lithologies of the Nixon Fork subterrane. Rocks in the Dyckman Mountain area are part of a broader facies belt that is transitional between the Nixon Fork carbonate platform to the west and deeper water, basinal lithologies (Minchumina “terrane”) to the east. Transitional facies patterns are complex because of Paleozoic shifts in the position of the platform margin, Mesozoic shortening, and Late Cretaceous-Tertiary disruption by strike-slip faulting.

  1. Measurement of sub-surface strata behaviour in bord and pillar mining: a case study

    International Nuclear Information System (INIS)

    Krishna, R.

    1991-01-01

    Ranigunj coalfield (India) has been facing significant problems due to subsidence as a result of underground mining of coal seams. The occurrence of the thick seams in close proximity, shallow depth, great variation in the nature of superincumbent strata from site to site, followed by the slow rate of extraction, has aggravated subsidence problems. In the recent past, many such workings have collapsed, damaging a large number of surface structures. In view of the aforesaid need, a comprehensive project financed by the Ministry of Energy (Coal), was undertaken by the Department of Mining Engineering, Indian Institute of Technology, Kharagpur, at a Colliery in Ranigunj Coalfield. This investigation revealed that the caving horizon occurred at 4 times the extracted seam height, which differs from the findings in the UK, USA, and Australia. Also, it appears possible to estimate strata displacements from geological and physicomechanical information from the overlying rocks using the bending moment principle. Further, it was observed that the shallow workings could give rise to a sink hole type of subsidence, which is dangerous and could adversely affect the environment, safety of the public and properties. 11 refs., 13 figs., 1 tab

  2. Identification of multiple magnetizations of the Ediacaran strata in South China

    Science.gov (United States)

    Jing, Xianqing; Yang, Zhenyu; Tong, Yabo; Wang, Heng; Xu, Yingchao

    2018-01-01

    A suspected Silurian remagnetization of the Ediacaran strata of South China was proposed decades ago by many researchers, but, there has been no systematic study of its causes and mechanisms. In this study, we investigate the multiphase remagnetization processes that affected the Ediacaran strata and the possible mechanisms of these remagnetization events. We conducted detailed palaeomagnetic, rock magnetic and scanning electron microscope (SEM) studies of samples from the Ediacaran strata in the Jiulongwan (JLWE, JLWS), Qinglinkou (QLK) and Sanxiarenjia (SXRJ) sections in the Three Gorges Area, South China. After removal of a recent viscous remanent magnetization below 150 °C, an intermediate temperature component (ITC; Dg = 27.6°, Ig = 45.3°, N = 12 sites, kg = 184.3, α95 = 3.2° for JLWE; Dg = 22°, Ig = 45.3°, N = 11 sites, kg = 789.2, α95 = 1.6° for JLWS; and Dg = 25.5°, Ig = 52.5°, N = 6 sites, kg = 533.4, α95 = 2.9° for SXRJ) was removed below 300 °C which coincides with the Jurassic results from South China, suggesting a pervasive Jurassic remagnetization. In addition, a high temperature component (HTC; Ds = 84.8°, Is = 19.2°, N = 9 sites, ks = 35.5, α95 = 8.8° for JLWE; Ds = 74.1°, Is = 49.4°, N = 7 sites, ks = 218.9, α95 = 4.1° for JLWS; and Ds = 89.5°, Is = 30.7°, N = 8 sites, ks = 129.2, α95 = 4.9° for SXRJ) was isolated between 300 and 480-540 °C. Rock magnetic and SEM studies suggest that the ITC and HTC are carried by pyrrhotite and magnetite, respectively. SEM observations also demonstrate the occurrence of massive authigenic magnetite in cavities or cracks, mineralogical changes from pyrite to Fe oxides, and the reaction between gypsum and Fe oxides. Based on similarities to the Silurian poles of South China, together with the SEM observations, we suggest that the HTC from the JLWE and SXRJ sections is a Silurian age remagnetization. The oxidation of iron sulphides and thermochemical sulphate reduction induced by the

  3. The Apuseni Mountains, Romania, a Variscan Collage of Ordovician Gondwanan Terranes

    Science.gov (United States)

    Balintoni, I. C.; Balica, C.; Zaharia, L.; Chen, F.; Cliveti, M.; Hann, H. P.; Ghergari, L.

    2007-12-01

    The basement of the Apuseni Mountains, Romania, consists of three pre-Variscan terranes, sutured during an Early Variscan amalgamation around 351 Ma (Balintoni et al., this volume). The northern Someş Terrane (ST) is predominantly gneissic, while the southern Baia de Arieş Terrane (BAT) is dominated by the presence of large carbonate lenses, although metagranites and other types of orthogneisses can be found. These two terranes are sutured through the Biharia terrane, probably an accreted island arc. LA-ICP-MS datings on zircons extracted from orthogneisses and metagranites were performed in order to constrain the age of ST and BAT. A number of previously CL-imaged crystals were ablated at the China's University of Geosciences, Wuhan. From ST we dated an orthogneiss occurring in structurally lowermost position, a metatuff situated in the upper strongly retrogressed part and a twenty detrital crystal population sampled from a metasandstone. The 206Pb/238U apparent ages were projected using the weighted average plots.A magmatic crystallization age of 472.8±5.0 Ma (Upper Early Ordovician) resulted for one of the orthogneiss samples, besides several older ages at 505.7, 566.3 and 708.2 Ma corresponding to inherited cores. Another sample from the same rock appeared strongly affected by lead loss during a later thermotectonic event, most of the apparent ages grouping around 352±14 Ma. This age is similar with the age of the suture between ST and BT (Balintoni et al., this volume). The main zircon population of one metatuff sample furnished an averaged age of 423±7.2 Ma, also found in two additional samples, but their significance is obscure for the moment. Two primary magmatic ages arise at 464.2 and 473.8 Ma, an older value of 758.7 Ma corresponding to an inherited core. Detrital zircon ages range between 534.8 and 2596.8 Ma. The younger value represents an upper age constraint for the protolith age of ST-rocks. From BAT we dated the Lupşa metaporphyroid and the

  4. Was there more space in the late Early Devonian for marine biodiversity to peak than in the early Late Ordovician?: A brief note

    Directory of Open Access Journals (Sweden)

    Ruban Dmitry A.

    2013-01-01

    Full Text Available After the so-called “Cambrian explosion”, marine biodiversity peaked either in the early Late Ordovician (as shown by the “classical” curves based on the extensive palaeontological data compilation or in the late Early Devonian (as shown by the “innovative” curve based on the sampling standardization. The brief review of the modern plate tectonic, palaeoclimatic, and eustatic reconstructions demonstrates that shelves, which likely provided the main space for biotic radiation, shrank, concentrated in the tropics, and were better connected in the late Early Devonian than in the early Late Ordovician. The results of the present analysis permit to hypothesize that there was more (or the same space for marine organisms to reach their maximum in their number in the early Late Ordovician relatively to the late Early Devonian. This is the only particular hypothesis, and the other extrinsic and intrinsic factors should be considered in further discussions.

  5. The Early Ordovician trilobite distribution and zonation of the East Baltic

    Directory of Open Access Journals (Sweden)

    Pärnaste, Helje

    2006-06-01

    Full Text Available Biozones of the East Baltic Early Ordovician trilobites were studied based on the trilobite distribution in northwestern Russia, Estonia, and Sweden. New data on trilobite distribution reveal the diachroneity of the lowest calcareous sediments of the Mäeküla Member, which forms the upper part of the Leetse Formation in the East Baltic. Trilobites of the Tremadoc Apatokephalus serratus and Megistaspis (Ekeraspis armata biozones are missing in the East Baltic, in contradiction to the suggestion of Balashova (Vopr. Paleontol., 1966, 5, 3–22. Some poorly preserved specimens probably belonging to Megistaspis (Paramegistaspis planilimbata (Angelin and also records of Pliomerops? linnarssoni (Wiman indicate that the Arenig Megistaspis (P. planilimbata Biozone of the Hunneberg Stage may be represented in some localities. The final delimitation of biozones in the Mäeküla and Päite members should improve when the ontogenetic and phylogenetic variation of the M. (Paramegistaspis lineage has been fully documented. Until then the Evropeites lamanskii Biozone is used in the East Baltic following Balashova, as indicated by the appearance of that taxon in most studied localities, marking the beginning of the Billingen Age. The succeeding Megalaspides (Megalaspides dalecarlicus Biozone is represented by the occurrence of at least its upper part in the Vassilkovo Beds in the St. Petersburg region, where Megalaspides paliformis Tjernvik occurs together with the index taxon (these taxa co-occur in the upper part of this zone in Sweden. The Päite Member in the East Baltic is correlated with the Megistaspis (P. estonica Biozone of the upper part of the Billingen Stage in Sweden.

  6. Response of beta diversity to pulses of Ordovician-Silurian mass extinction.

    Science.gov (United States)

    Darroch, Simon A F; Wagner, Peter J

    2015-02-01

    Ecologists are increasingly using the fossil record of mass extinction to build predictive models for the ongoing biodiversity crisis. During mass extinctions, major depletions in global (i.e., gamma) diversity may reflect decrease in alpha diversity (i.e., local assemblages support fewer taxa), and/or decrease in beta diversity (such that similar pools of taxa are common to a greater number of local areas). Contrasting the effects of extinction on alpha and beta diversity is therefore central to understanding how global richness becomes depleted over these critical events. Here we investigate the spatial effects of mass extinction by examining changes in alpha, beta, and gamma diversity in brachiopod communities over both pulses of Ordovician-Silurian extinction (-445.2 and -438.8 million years ago), which had dramatically different causal mechanisms. We furthermore reconstruct geographic range sizes for brachiopod genera to test competing models for drivers of beta diversity change. We find that: (1) alpha and beta diversity respond differently to extinction; (2) these responses differ between pulses of extinction; (3) changes in beta diversity associated with extinction are accompanied by changes in geographic range size; and (4) changes in global beta diversity were driven by the extinction of taxa with statistically small and large ranges, rather than range expansion/contraction in taxa that survive into the aftermath. A symptom of ongoing biotic crisis may therefore be the extinction of specific narrow- or wide-ranging taxa, rather than the global proliferation of opportunistic and "disaster" forms. In addition, our results illustrate that changes in beta diversity on these longer timescales may largely be dictated by emplacement and removal of barriers to dispersal. Lastly, this study reinforces the utility of the fossil record in addressing questions surrounding the role of global-scale processes (such as mass extinctions) in sculpting and assembling

  7. Ancestral morphology of crown-group molluscs revealed by a new Ordovician stem aculiferan.

    Science.gov (United States)

    Vinther, Jakob; Parry, Luke; Briggs, Derek E G; Van Roy, Peter

    2017-02-23

    Exceptionally preserved fossils provide crucial insights into extinct body plans and organismal evolution. Molluscs, one of the most disparate animal phyla, radiated rapidly during the early Cambrian period (approximately 535-520 million years ago (Ma)). The problematic fossil taxa Halkieria and Orthrozanclus (grouped in Sachitida) have been assigned variously to stem-group annelids, brachiopods, stem-group molluscs or stem-group aculiferans (Polyplacophora and Aplacophora), but their affinities have remained controversial owing to a lack of preserved diagnostic characters. Here we describe a new early sachitid, Calvapilosa kroegeri gen. et sp. nov. from the Fezouata biota of Morocco (Early Ordovician epoch, around 478 Ma). The new taxon is characterized by the presence of a single large anterior shell plate and polystichous radula bearing a median tooth and several lateral and uncinal teeth in more than 125 rows. Its flattened body is covered by hollow spinose sclerites, and a smooth, ventral girdle flanks an extensive mantle cavity. Phylogenetic analyses resolve C. kroegeri as a stem-group aculiferan together with other single-plated forms such as Maikhanella (Siphogonuchites) and Orthrozanclus; Halkieria is recovered closer to the aculiferan crown. These genera document the stepwise evolution of the aculiferan body plan from forms with a single, almost conchiferan-like shell through two-plated taxa such as Halkieria, to the eight-plated crown-group aculiferans. C. kroegeri therefore provides key evidence concerning the long debate about the crown molluscan affinities of sachitids. This new discovery strongly suggests that the possession of only a single calcareous shell plate and the presence of unmineralised sclerites are plesiomorphic (an ancestral trait) for the molluscan crown.

  8. 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.

  9. Identification of the Paleocene-Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

    Science.gov (United States)

    Frieling, Joost; Huurdeman, Emiel P.; Rem, Charlotte C. M.; Donders, Timme H.; Pross, Jörg; Bohaty, Steven M.; Holdgate, Guy R.; Gallagher, Stephen J.; McGowran, Brian; Bijl, Peter K.

    2018-02-01

    Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene-Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene-Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the

  10. 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

  11. 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.

  12. Lower and Middle Ordovician conodonts of Laurentian affinity from blocks of limestone in the Rosroe Formation, South Mayo Trough, western Ireland and their palaeogeographic implication

    DEFF Research Database (Denmark)

    Stouge, Svend; Harper, David A. T.; Sevastopulo, George D.

    2016-01-01

    at offshore 'peri-Laurentian' islands, close to and along the Laurentian margin. During collapse of the carbonate system in the late Mid Ordovician, the blocks were transported down a steep slope and into deep-water by debris flows, mixing with other rock types now found in the coarse polymict clastics......The Middle Ordovician Rosroe Formation consists of some 1350m of coarse, mainly siliciclastic to volcaniclastic sedimentary rocks, deposited in a submarine fan environment, and is restricted to the southern limb of the South Mayo Trough, western Ireland. Discrete allochthonous blocks, reaching 5m...

  13. Origin of discontinuities in coal-bearing strata at roaring creek (basal Pennsylvanian of Indiana)

    Science.gov (United States)

    Nelson, W.J.; Eggert, D.L.; DiMichele, W.A.; Stecyk, A.C.

    1985-01-01

    Basal Pennsylvanian coal-bearing strata exposed along Roaring Creek, west-central Indiana, exhibit extreme lateral discontinuity. Coal seams abruptly change in thickness and elevation; they split, grade into shale, are cut out by channels and disrupted by soft-sediment deformational structures. Initial sediments were laid down by a network of southwest-flowing streams that traversed a deeply channelized upland surface of Mississippian carbonate rocks. Channels aggraded rapidly as uplands were worn down, so the region changed through time from uplands to upper deltaic plain. Local environments included channels, localized point bars, small natural levees and crevasse splays, overbank deposits, and swamps. Differential compaction and subsidence, slumping stream banks, and possibly collapsing sinkholes influenced sedimentation. As a consequence, coals are too discontinuous for economical mining, although they are locally thick and high in quality. ?? 1985.

  14. Os monumentos de Atenas na Lisístrata de Aristófanes

    Directory of Open Access Journals (Sweden)

    Adriane da Silva Duarte

    2001-12-01

    Full Text Available Na Lisístrata de Aristofanes, os monumentos de Atenas desempenham um papel importante para o desenvolvimento da trama cômica. Em maior evidência, a Acrópole, ocupada pelas mulheres, e parte essencial do plano da heroína para por fim a guerra fratricida entre espartanos e atenienses. 0s homens, por sua vez, excluídos da cidade alta, fincam o pé na Ágora, tomando por símbolos de sua resistência o grupo escultórico dos tiranicidas e a amazonomaquia de Mícon. Pretende-se aqui investigar as razões que levaram o semicoro masculino a escolher justamente esses monumentos para ilustrar sua fala.

  15. Solute concentrations influence microbial methanogenesis in coal-bearing strata of the Cherokee basin, USA

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    Matthew F Kirk

    2015-11-01

    Full Text Available Microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4-1.1 m coalbeds with marginal thermal maturities (0.5-0.7 %Ro that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na-Cl type with total dissolved solids (TDS content ranging from 34.9 to 91.3 g L-1. Gas dryness values [C1/(C2+C3] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65‰ and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%, and few archaeal sequences (avg 4.2% were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute

  16. Solute Concentrations Influence Microbial Methanogenesis in Coal-bearing Strata of the Cherokee Basin, USA.

    Science.gov (United States)

    Kirk, Matthew F; Wilson, Brien H; Marquart, Kyle A; Zeglin, Lydia H; Vinson, David S; Flynn, Theodore M

    2015-01-01

    Microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4-1.1 m) coalbeds with marginal thermal maturities (0.5-0.7% R o ) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na-Cl type with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L(-1). Gas dryness values [C1/(C2 + C3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute content

  17. Comparative Sex Chromosome Genomics in Snakes: Differentiation, Evolutionary Strata, and Lack of Global Dosage Compensation

    Science.gov (United States)

    Zektser, Yulia; Mahajan, Shivani; Bachtrog, Doris

    2013-01-01

    Snakes exhibit genetic sex determination, with female heterogametic sex chromosomes (ZZ males, ZW females). Extensive cytogenetic work has suggested that the level of sex chromosome heteromorphism varies among species, with Boidae having entirely homomorphic sex chromosomes, Viperidae having completely heteromorphic sex chromosomes, and Colubridae showing partial differentiation. Here, we take a genomic approach to compare sex chromosome differentiation in these three snake families. We identify homomorphic sex chromosomes in boas (Boidae), but completely heteromorphic sex chromosomes in both garter snakes (Colubridae) and pygmy rattlesnake (Viperidae). Detection of W-linked gametologs enables us to establish the presence of evolutionary strata on garter and pygmy rattlesnake sex chromosomes where recombination was abolished at different time points. Sequence analysis shows that all strata are shared between pygmy rattlesnake and garter snake, i.e., recombination was abolished between the sex chromosomes before the two lineages diverged. The sex-biased transmission of the Z and its hemizygosity in females can impact patterns of molecular evolution, and we show that rates of evolution for Z-linked genes are increased relative to their pseudoautosomal homologs, both at synonymous and amino acid sites (even after controlling for mutational biases). This demonstrates that mutation rates are male-biased in snakes (male-driven evolution), but also supports faster-Z evolution due to differential selective effects on the Z. Finally, we perform a transcriptome analysis in boa and pygmy rattlesnake to establish baseline levels of sex-biased expression in homomorphic sex chromosomes, and show that heteromorphic ZW chromosomes in rattlesnakes lack chromosome-wide dosage compensation. Our study provides the first full scale overview of the evolution of snake sex chromosomes at the genomic level, thus greatly expanding our knowledge of reptilian and vertebrate sex chromosomes

  18. Does the golden lion tamarin, Leontopithecus rosalia (Primates: Callitrichidae, select a location whithin the forest strata for long distance communication?

    Directory of Open Access Journals (Sweden)

    Vera Sabatini

    2010-04-01

    Full Text Available The effectiveness of auditory signals for long distance communication depends on environmental, biological and behavioral factors. Because the environment is not homogenous, it is expected that vocalizing animals would emit signals from locations (perches that would facilitate call propagation and perception. Perching behavior has been widely documented in birds, but not in primates. The aim of this study was to ascertain whether golden lion tamarins - Leontopithecus rosalia (Linnaeus, 1766 - emit long calls from places (perch within the forest strata that are higher above the ground with respect to places used for baseline behaviors. We compared the forest stratum (upper, middle and lower strata and habitat type (hill, swamp and lowland forests used for long calls with those used for other behaviors. The focal animal technique (n = 4 of 10 minutes with instantaneous sampling at two minutes were used if the subjects were not emitting long calls, and the all-occurrences technique if a focal individual emitted a two-phrase long call. Golden lion tamarins used all strata in all habitat types, including the ground, when they were not emitting long calls, but vocalized long calls most often from the upper strata, just underneath the canopy, in the three habitats studied. From a total of 29 bouts of long calls, 21 were initiated by individuals that were in the lower stratum; however, these individuals subsequently migrated to the upper stratum, while still vocalizing. Calling from the upper strata of the forest, just underneath canopy could improve sound transmission, perception, visual contact or a combination of these types of communication. Based on these considerations, we hypothetize that by placing themselves in the upper strata of the forest when emitting calls, golden lion tamarins enhance their likelhood to locate other callers, not only be improving sound reception, but also by increasing their chances to make visual contact with them.

  19. 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.

  20. 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.

  1. The petroleum system of the lower Palaeozoic strata in the central part of the Baltic basin

    Science.gov (United States)

    Lazauskiene, Jurga; Zdanaviciute, Onyte

    2013-04-01

    the end of Silurian, while the basic phase is thought to occur in Devonian and Permian. Different source rocks contributed to the hydrocarbon expulsion. Slow deposition and tectonically stable regime ensured slow formation of the oil and gase-condensate fields with replenishing oil portions incoming with time: e.g. Cambrian oil traps could accumulate also Ordovician and Silurian oils.

  2. Mass-production of Cambro-Ordovician quartz-rich sandstone as a consequence of chemical weathering of Pan-African terranes: Environmental implications [rapid communication

    Science.gov (United States)

    Avigad, D.; Sandler, A.; Kolodner, K.; Stern, R. J.; McWilliams, M.; Miller, N.; Beyth, M.

    2005-12-01

    A vast sheet of mature quartz sand blanketed north Africa and Arabia from the Atlantic coast to the Persian Gulf in Cambro-Ordovician times. U-Pb geochronology of a representative section of Cambrian sandstone in southern Israel shows that these sediments are dominated by 550-650 Ma detrital zircons derived from Neoproterozoic Pan-African basement. The short time lag between magmatic consolidation of a Pan-African source and deposition of its erosional products indicates that, despite their significant mineralogical maturity, the voluminous quartz-rich sandstones on the northern margin of Gondwana are essentially first-cycle sediments. Mass production of these voluminous first-cycle quartz-rich sandstones resulted from widespread chemical weathering of the Pan-African continental basement. We suggest that conditions favoring silicate weathering, particularly a warm and humid climate, low relief and low sedimentation rates prevailed over large tracts of Gondwana in the aftermath of the Pan-African orogeny. An unusually corrosive Cambro-Ordovician atmosphere and humid climate enhanced chemical weathering on the vegetation-free landscape. We infer that late Neoproterozoic-Cambro-Ordovician atmospheric pCO 2 rose as a consequence of widespread late Neoproterozoic volcanism, followed by an uptake of CO 2 by chemical weathering to produce the Cambro-Ordovician sandstone as a negative feedback.

  3. A reworked Lake Zone margin: Chronological and geochemical constraints from the Ordovician arc-related basement of the Hovd Zone (western Mongolia)

    Czech Academy of Sciences Publication Activity Database

    Soejono, I.; Buriánek, D.; Janoušek, V.; Svojtka, Martin; Čáp, P.; Erban, V.; Ganpurev, D.

    294/295, December (2017), s. 112-132 ISSN 0024-4937 Institutional support: RVO:67985831 Keywords : Ordovician magmatic arc * Mid-Silurian intra-plate magmatism * Hovd Zone * Reworked Lake Zone Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 3.677, year: 2016

  4. 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 ...

  5. Fossil assemblages from the Middle Ordovician Šárka Fromation at Praha - Červený vrch Hill (Prague Basin, Barrandian area)

    Czech Academy of Sciences Publication Activity Database

    Kraft, P.; Budil, P.; Chlupáč, I.; Fatka, O.; Kraft, J.; Mikuláš, Radek; Mergl, M.; Bruthansová, J.

    2003-01-01

    Roč. 78, č. 2 (2003), s. 99-101 ISSN 1214-1119 Institutional research plan: CEZ:AV0Z3013912 Keywords : trace fossils * Šárka Formation * Ordovician Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/bulletin/contents/2003/vol78no2/02-kraft.pdf

  6. 78 FR 56944 - Strata Energy, Inc. (Ross In Situ Recovery Uranium Project); Notice of Atomic Safety and...

    Science.gov (United States)

    2013-09-16

    ... NUCLEAR REGULATORY COMMISSION [Docket No. 40-9091-MLA; ASLBP No. 12-915-01-MLA-BD01] Strata Energy, Inc. (Ross In Situ Recovery Uranium Project); Notice of Atomic Safety and Licensing Board Reconstitution Pursuant to 10 CFR 2.313(c) and 2.321(b), the Atomic Safety and Licensing Board (Board) in the...

  7. Hydrocarbon preservation conditions in Mesozoic–Paleozoic marine strata in the South Yellow Sea Basin

    Directory of Open Access Journals (Sweden)

    Jie Liang

    2017-11-01

    Full Text Available In the South Yellow Sea Basin, Mesozoic–Paleozoic marine strata are generally well developed with large thickness, and they are characterized by multi-source and multi-stage hydrocarbon accumulation, providing a material basis for the formation of large-scale oil and gas fields. However, no substantial breakthrough has been made in this area. Based on previous research results, the complex tectonic pattern of this superimposed basin was formed by multi-stage tectonic movements and the favorable static conditions for hydrocarbon preservation were reworked or destroyed by later superimposition. Therefore, hydrocarbon preservation conditions are the key factors for restricting the breakthrough of marine oil and gas exploration in this area. In this paper, hydrocarbon preservation conditions of marine strata in the South Yellow Sea Basin were comprehensively analyzed from many aspects, such as tectonic movement, source conditions, caprock characteristics, magmatic activities, and hydrogeological and hydrogeochemical characteristics. It is indicated that the complex tectonic pattern of the South Yellow Sea Basin is resulted from tectonic events in multiple stages, and the development and evolution of regional source rocks are mainly controlled by two stages (i.e., the stable evolution stage of Mesozoic–Paleozoic marine basin and the Mesozoic–Cenozoic tectonic pattern transformation and basin formation stage, so the characteristics of differential oil and gas preservation are presented. Besides, better marine hydrocarbon preservation preconditions in this area are weaker tectonic reworking, development of high-quality thick source rocks, good vertical sealing capacity of caprocks, weaker magmatic activity and confined hydrogeological conditions. It is concluded that the Laoshan Uplift in the central part of the South Yellow Sea Basin is structurally stable with weaker faulting and magmatic activities, so it is better in oil and gas preservation

  8. Hierarchical sampling of multiple strata: an innovative technique in exposure characterization

    International Nuclear Information System (INIS)

    Ericson, J.E.; Gonzalez, Elisabeth J.

    2003-01-01

    Sampling of multiple strata, or hierarchical sampling of various exposure sources and activity areas, has been tested and is suggested as a method to sample (or to locate) areas with a high prevalence of elevated blood lead in children. Hierarchical sampling was devised to supplement traditional soil lead sampling of a single stratum, either residential or fixed point source, using a multistep strategy. Blood lead (n=1141) and soil lead (n=378) data collected under the USEPA/UCI Tijuana Lead Project (1996-1999) were analyzed to evaluate the usefulness of sampling soil lead from background sites, schools and parks, point sources, and residences. Results revealed that industrial emissions have been a contributing factor to soil lead contamination in Tijuana. At the regional level, point source soil lead was associated with mean blood lead levels and concurrent high background, and point source soil lead levels were predictive of a high percentage of subjects with blood lead equal to or greater than 10 μg/dL (pe 10). Significant relationships were observed between mean blood lead level and fixed point source soil lead (r=0.93; P 2 =0.72 using a quadratic model) and between residential soil lead and fixed point source soil lead (r=0.90; P 2 =0.86 using a cubic model). This study suggests that point sources alone are not sufficient for predicting the relative risk of exposure to lead in the urban environment. These findings will be useful in defining regions for targeted or universal soil lead sampling by site type. Point sources have been observed to be predictive of mean blood lead at the regional level; however, this relationship alone was not sufficient to predict pe 10. It is concluded that when apparently undisturbed sites reveal high soil lead levels in addition to local point sources, dispersion of lead is widespread and will be associated with a high prevalence of elevated blood lead in children. Multiple strata sampling was shown to be useful in

  9. A study of calcium intake and sources of calcium in adolescent boys and girls from two socioeconomic strata, in Pune, India.

    Science.gov (United States)

    Sanwalka, Neha J; Khadilkar, Anuradha V; Mughal, M Zulf; Sayyad, Mehmood G; Khadilkar, Vaman V; Shirole, Shilpa C; Divate, Uma P; Bhandari, Dhanshari R

    2010-01-01

    Adequate intake of calcium is important for skeletal growth. Low calcium intake during childhood and adolescence may lead to decreased bone mass accrual thereby increasing the risk of osteoporotic fractures. Our aim was to study dietary calcium intake and sources of calcium in adolescents from lower and upper economic strata in Pune, India. We hypothesized that children from lower economic strata would have lower intakes of calcium, which would predominantly be derived from non-dairy sources. Two hundred male and female adolescents, from lower and upper economic stratum were studied. Semiquantitative food frequency questionnaire was used to evaluate intakes of calcium, phosphorus, oxalic acid, phytin, energy and protein. The median calcium intake was significantly different in all four groups, with maximum intake in the upper economic strata boys (893 mg, 689-1295) and lowest intake in lower economic strata girls (506 mg, 380-674). The median calcium intake in lower economic strata boys was 767 mg (585-1043) and that in upper economic strata girls was 764 mg (541-959). The main source of calcium was dairy products in upper economic strata adolescents while it was dark green leafy vegetables in lower economic strata adolescents. The median calcium intake was much lower in lower economic strata than in the upper economic strata both in boys and girls. Girls from both groups had less access to dairy products as compared to boys. Measures need to be taken to rectify low calcium intake in lower economic strata adolescents and to address gender inequality in distribution of dairy products in India.

  10. Epidemiological and clinical profile of paediatric malaria: a cross sectional study performed on febrile children in five epidemiological strata of malaria in Cameroon.

    Science.gov (United States)

    Kwenti, Tebit Emmanuel; Kwenti, Tayong Dizzle Bita; Latz, Andreas; Njunda, Longdoh Anna; Nkuo-Akenji, Theresa

    2017-07-17

    In the wake of a decline in global malaria, it is imperative to describe the epidemiology of malaria in a country to inform control policies. The purpose of this study was to describe the epidemiological and clinical profile of paediatric malaria in five epidemiological strata of malaria in Cameroon including: the Sudano-sahelian (SS) strata, the High inland plateau (HIP) strata, the South Cameroonian Equatorial forest (SCEF) strata, the High western plateau (HWP) strata, and the Coastal (C) strata. This study involved 1609 febrile children (≤15 years) recruited using reference hospitals in the five epidemiological strata. Baseline characteristics were determined; blood glucose level was measured by a glucometer, malaria parasitaemia was assessed by Giemsa microscopy, and complete blood count was performed using an automated hematology analyser. Severe malaria was assessed and categorized based on WHO criteria. An overall prevalence of 15.0% (95% CI: 13.3-16.9) for malaria was observed in this study. Malaria prevalence was significantly higher in children between 60 and 119 months (p malaria (SM) attack in this study was 29.3%; SM was significantly higher in children below 60 months (p malaria anaemia and impaired consciousness. The majority (73.2%) of SM cases were in group 1 of the WHO classification of severe malaria (i.e. the most severe form). The malaria case-fatality rate was 5.8%; this was higher in Ngaoundere (HIP strata) (p = 0.034). In this study, malaria prevalence decreased steadily northward, from the C strata in the South to the SS strata in the North of Cameroon, meanwhile the mortality rate associated with malaria increased in the same direction. On the contrary, the rate of severe malaria attack was similar across the different epidemiological strata. Immunoepidemiological studies will be required to shed more light on the observed trends.

  11. Mineralogy and petrography of samples of Permo-Triassic sedimentary strata from Cumbria

    International Nuclear Information System (INIS)

    Kemp, S.J.; Milodowski, A.E.; Bloodworth, A.J.

    1989-03-01

    The mineralogy and petrography of Permo-Triassic sediments from Cumbria are described. The samples are duplicates of those selected for sorption experiments by Harwell Laboratory and are considered representative of Permo-Triassic strata underlying the BNFL Sellafield site. The regional geological context of the samples is briefly discussed. X-ray diffraction analysis indicates that the St Bees Sandstone and Eden Shales samples are predominantly composed of quartz with minor feldspar, gypsum and hematite. The clay assemblage is formed of dioctahedral mica and trioctahedral chloride with minor kaolinite. Diagnostic testing also reveals the presence of corrensite, a regularly interstratified chlorite-smectite, in one of the samples. Possible diagenetic processes responsible for corrensite formation, including the alteration of originally deposited smectite by magnesium-rich pore waters, are discussed. Modelling of the diffraction profile indicates that the chlorite and corrensite are iron-rich species. Back scattered electron microscopy shows the samples to be typical red bed sediments exhibiting framework grain dissolution, the breakdown and replacement of unstable ferromagnesian minerals being accompanied by the precipitation of hematite and anatase. Particle-size analysis shows similar distributions for the St Bees Sandstone samples but a greater proportion of clay material in the Eden Shales. (author)

  12. Socioeconomic strata as a predictor factor for consistent condom use among adolescents

    Directory of Open Access Journals (Sweden)

    Ramiro Caballero Hoyos

    Full Text Available INTRODUCTION: Socioeconomic level plays an important role in health inequalities. In Mexico, the highest prevalence of AIDS cases is among individuals of lower socioeconomic level. The purpose of the study was to describe the socioeconomic level (adjusted for psychosocial, situational and demographic variables as a predictor factor for the consistent condom use among adolescents of Guadalajara, Mexico. METHODS: A sample of 1,410 adolescents, aged 15 to 19 years, drawn from a previous survey stratified by age, gender and socioeconomic strata was included in the study. Analysis was performed in 251 adolescents who reported sexual activity. Statistical analysis was performed using Chi-square, t-test, ANOVA, and logistic regression. RESULTS: The frequency of consistent condom use was 30.7% and there was a prevalence of irregular use. The highest social level was the main predictor (OR= 11.1, CI 95%=2.6-47.6. Others significant predictors were male gender, peer support and better knowledge about HIV/AIDS. CONCLUSION: Socioeconomic level is an important predictor factor for consistent condom use.

  13. Strata-1: An International Space Station Experiment into Fundamental Regolith Processes in Microgravity

    Science.gov (United States)

    Fries, M.; Abell, P.; Brisset, J.; Britt, D.; Colwell, J.; Durda, D.; Dove, A.; Graham, L.; Hartzell, C.; John, K.; hide

    2016-01-01

    The Strata-1 experiment will study the evolution of asteroidal regolith through long-duration exposure of simulant materials to the microgravity environment on the International Space Station (ISS). Many asteroids feature low bulk densities, which implies high values of porosity and a mechanical structure composed of loosely bound particles, (i.e. the "rubble pile" model), a prime example of a granular medium. Even the higher-density, mechanically coherent asteroids feature a significant surface layer of loose regolith. These bodies are subjected to a variety of forces and will evolve in response to very small perturbations such as micrometeoroid impacts, planetary flybys, and the YORP effect. Our understanding of this dynamical evolution and the inter-particle forces involved would benefit from long-term observations of granular materials exposed to small vibrations in microgravity. A detailed understanding of asteroid mechanical evolution is needed in order to predict the surface characteristics of as-of-yet unvisited bodies, to understand the larger context of samples collected by missions such as OSIRIS-REx and Hayabusa 1 and 2, and to mitigate risks for both manned and unmanned missions to asteroidal bodies. Understanding regolith dynamics will inform designs of how to land and set anchors, safely sample/move material on asteroidal surfaces, process large volumes of material for in situ resource utilization (ISRU) purposes, and, in general, predict behavior of large and small particles on disturbed asteroid surfaces.

  14. 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

  15. The diploporite blastozoan Lepidocalix pulcher from the Middle Ordovician of northern Algeria: Taxonomic revision and palaeoecological implications

    Directory of Open Access Journals (Sweden)

    Yamouna Makhlouf

    2017-06-01

    Full Text Available We present revision of the taxonomy and palaeoecology of the Ordovician aristocystitid Lepidocalix pulcher from the Zaouïa of Stita (Great Kabylia, Algeria. An emended diagnosis is proposed, highlighting the four-fold ambulacral system and the typical thecal plating organised in circlets. Lepidocalix is here assigned to the subfamily Calicinae of the family Aristocystitidae. The latex casts show fitted sutures between plates, slightly abraded spines, and well-preserved oral surface. The thecal plates possess up to three dipores, each, included into the spines. The presence of such covered diplopores would have reduced the respiration rate, by restricting their exchange surface area. The spines covering the dipores are not articulated and they could have a protective role. Lepidocalix is interpreted as stationary epifauna, probably using iceberg strategy to be stabilized into the soft substrate.

  16. 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.

  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. First description of Skolithos burrows from the Cambrian–Ordovician boundary interval of the Central Anti-Atlas, Morocco

    Directory of Open Access Journals (Sweden)

    Abdelfattah Azizi

    2017-07-01

    Full Text Available Skolithos burrows indicate high-energy nearshore environment. In this paper, abundant Scolithos burrows from two particular levels of the Cambrian–Ordovician boundary interval of the Central Anti-Atlas, Morocco, are described for the first time. The first level occurs at the boundary between the Azlag Formation and Jbel Lmgaysmat Formation (Furongian, where the burrows are 5–80 cm long and 3–7 mm wide, straight to slightly curved, with mostly circular, but sometimes also oval apertures. The second level occurs within the unconformity underlining the Tremadocian cycle (Fezouata Shale. The burrows of Skolithos linearis associated with that level are straight to slightly curved, 2–15 cm long and 2–4 mm wide. The absence of encrustation above the burrowed beds indicates that these traces were made in a soft sediment.

  19. Significance of nearshore trace-fossil assemblages of the cambro-ordovician deadwood formation and Aladdin Sandstone, South Dakota

    Science.gov (United States)

    Stanley, T.M.; Feldmann, R.M.

    1998-01-01

    The Cambro-Ordovician Deadwood Formation and Aladdin Sandstone represent intertidal and subtidal, nearshore deposystems that contain few well-preserved body fossils, but contain abundant trace fossils. The present study uses the much neglected trace-fossil fauna to describe the diverse paleoenvironments represented in the Deadwood-Aladdin deposystems, and to better understand the environmental conditions that controlled benthic life in the Early Paleozoic. The Deadwood-Aladdin ichnotaxa can be separated into three distinct assemblages based on the changing sedimentologic and hydrodynamic conditions that existed across the Cambro-Ordovician shelf. Trace-fossil assemblages and corresponding lithofacies characteristics indicate that the Deadwood-Aladdin deposystems formed within an intertidal-flat and subtidal-shelf environment. Based on the distribution and numbers of preserved ichnotaxa, the intertidal flat can be subdivided further into an ecologically stressful inner sand-flat environment, and a more normal marine outer sand-flat environment, both of which belong to a mixed, Skolithos-Cruziana softground ichnofacies. The inner sand flat is characterized by low diversity, low numbers, and a general lack of complexly constructed ichnotaxa. Trace fossils common to both assemblages tend to be smaller in the inner flat compared to the outer sand flat. Taphonomic effects, such as substrate type and sediment heterogeneity, also aid in differentiating between the inner and outer sand-flat assemblages. The subtidal shelf environment is categorized in the Cruziana Ichnofacies. Ichnological evidence of periodic tempestite deposition and hardground development within this subtidal regime is manifested by high diversity and low abundance of ichnogenera.

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

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    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.

  1. Tetradiid-siliceous sponge patch reefs from the Xiazhen Formation (late Katian), southeast China: A new Late Ordovician reef association

    Science.gov (United States)

    Kwon, Sung-Wook; Park, Jino; Choh, Suk-Joo; Lee, Dong-Chan; Lee, Dong-Jin

    2012-08-01

    Decimetre-scale domal to tabular patch reefs consisting of dendroid tetradiids are found in the Late Ordovician (late Katian) Xiazhen Formation, southeast China. It is intriguing to observe that siliceous sponges occur together with the tetradiids in many patch reefs, as this has not been previously reported. The tetradiid Rhabdotetradium jiangshanense are preserved in situ and the siliceous sponges, where present, as spicule networks. Calcimicrobe Ortonella encrusting tetradiid tubes and burrows filled with faecal pellets also constitute as subordinate components of the patch reef. The tetradiid tubes are regarded as frame-builders that are commonly surrounded and encrusted by the siliceous sponges. The sponges, wherever observed, form the bulk of the patch reef and are regarded as a primary constructor as well as binder of the patch reef. Burrows filled with faecal pellets often penetrate the area between tetradiids and sponge spicule networks in the boundstone and these are considered to be the loci of dweller. Where the sponges and tetradiids co-occur, the tetradiid tubes are sparsely distributed and commonly display non-quadripartite fission (i.e., bipartite or tripartite). In contrast, where the sponges are rare in the patch reef, the tetradiid tubes are densely spaced and predominantly display quadripartite fission. This indicates that the tetradiid growth was influenced by the presence of siliceous sponges. This finding of the new Late Ordovician reef association and their mutual interplay extend our understanding of the Early Palaeozoic carbonate reefs. It reaffirms the need for multidisciplinary studies of carbonate buildups where similar interactions with siliceous sponges might have been overlooked.

  2. Probiotics prevent growth deficit of colon wall strata of malnourished rats post-lactation

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    Dirlene P. Lima

    2012-09-01

    Full Text Available The objective of this study was to analyze morphometrically the colon wall strata of malnourished rats supplemented with probiotics. Sixteen recently weaned Wistar rats (Rattus norvegicus were distributed into four groups: animals that received commercial chow (G1, n = 4; animals that received the same feed as G1 and were supplemented with probiotics (G2, n = 4; animals that received chow with 4% of proteins (G3, n = 4; animals that received the same feed as G3 and were supplemented with probiotics (G4, n = 4. After 12 weeks, the proximal colon was collected and submitted to histological processing. Three-µm cuts were stained with H.E., Periodic Acid Schifff (P.A.S. + diasthasis solution and Alcian Blue (A.B. pH 2.5 and pH 1.0. The morphometric analysis of the intestinal wall showed that the supplementation with ABT-4 probiotic culture prevents the growth deficit of colon wall strata that normally occurs in malnourished rats right after lactation. Besides, no alteration was observed in the proportion of the number of globet cells in relation to the number of enterocytes in malnourished rats, regardless of the supplementation with probiotics.Objetivou-se analisar morfometricamente os estratos da parede do cólon de ratos desnutridos e suplemen-tados com probióticos. Utilizaram-se 16 ratos (Rattus norvegicus Wistar, recém-desmamados, distribuídos em quatro grupos: animais que receberam a ração comercial (G1, n = 4; animais que receberam a mesma ração do grupo G1 e que foram suplementados com probióticos (G2, n = 4; animais que receberam uma ração com 4% de proteínas (G3, n = 4; animais que receberam a mesma ração do grupo G3 e que foram suplementados com probióticos (G4, n = 4. Após 12 semanas, o cólon foi coletado e submetido a rotina de processamento histológico. Cortes de 3µm foram corados com H.E., Periodic Acid Schifff (P.A.S. + solução de diástase e Alcian Blue (A.B. pH 2,5 e pH 1,0. A análise morfométrica da parede

  3. Basal keratinocytes contribute to all strata of the adult zebrafish epidermis.

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    Raymond T H Lee

    Full Text Available The epidermis of terrestrial vertebrates is a stratified epithelium and forms an essential protective barrier. It is continually renewed, with dead corneocytes shed from the surface and replaced from a basal keratinocyte stem cell population. Whilst mouse is the prime model system used for epidermal studies, there is increasing employment of the zebrafish to analyse epidermis development and homeostasis, however the architecture and ontogeny of the epidermis in this system are incompletely described. In particular, it is unclear if adult zebrafish epidermis is derived entirely from the basal epidermal stem cell layer, as in the mouse, or if the most superficial keratinocyte layer is a remnant of the embryonic periderm. Furthermore, a relative paucity of cellular markers and genetic reagents to label and manipulate the basal epidermal stem cell compartment has hampered research. Here we show that the type I keratin, krtt1c19e, is a suitable marker of the basal epidermal layer and identify a krtt1c19e promoter fragment able to drive strong and specific expression in this cell type. Use of this promoter to express an inducible Cre recombinase allowed permanent labelling of basal cells during embryogenesis, and demonstrated that these cells do indeed generate keratinocytes of all strata in the adult epidermis. Further deployment of the Cre-Lox system highlighted the transient nature of the embryonic periderm. We thus show that the epidermis of adult zebrafish, as in the mouse, derives from basal stem cells, further expanding the similarities of epidermal ontogeny across vertebrates. Future use of this promoter will assist genetic analysis of basal keratinocyte biology in zebrafish.

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

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    Emílio Alberto Amaral Soares

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

  5. Paleogene strata of the Eastern Los Angeles basin, California: Paleogeography and constraints on neogene structural evolution

    Science.gov (United States)

    McCulloh, T.H.; Beyer, L.A.; Enrico, R.J.

    2000-01-01

    Post-Paleogene dextral slip of 8-9 km is demonstrated for the southeastern part of the Whittier fault zone in the eastern Los Angeles basin area of southern California. A linear axis of greatest thickness for the combined upper Paleocene and lower to lower-middle Eocene clastic formations intersects the fault zone and is offset by it to give the new measure. Fragmentary evidence hints that the Whittier structural zone may have exerted control on bathymetric-topographic relief and sedimentation even in latest Paleocene (ca. 54 Ma). A clear topographic influence was exerted by 20-17 Ma. Strike-slip and present deformational style is younger than ca. 8 Ma. Our Paleogene isopach map extends as far west as long 117??58'W and is a foundation for companion zonal maps of predominant lithology and depositional environments. Integration of new palynological data with published biostratigraphic results and both new and published lithologic and sedimentological interpretations support the zonal maps. Reconstruction of marine-nonmarine facies and fragmented basin margins yields a model for the northeastern corner of a Paleogene coastal basin. Palinspastic adjustment for the Neogene-Quaternary Whittier fault offset and a reasoned westerly extension of the northern edge of the basin model yield a reconstruction of Paleogene paleogeography-paleoceanography. Our reconstruction is based partly on the absence of both Paleocene and Eocene deposits beneath the unconformable base of the middle Miocene Topanga Group in a region nowhere less than 15 km wide between the Raymond-Sierra Madre-Cucamonga fault zone and the northern edge of the Paleocene basin. Thus, Paleogene strata of the Santa Monica Mountains could not have been offset from the northern extension of the Santa Ana Mountains by sinistral slip on those boundary faults. Structural rearrangements needed to accommodate the clockwise rotation of the western Transverse Ranges from the early Miocene starting position are thereby

  6. Assessing subsurface strata using geophysical and geotechnical methods for designing structures near ground cracks

    Science.gov (United States)

    AlFouzan, F.; Dafalla, M.; Mutaz, E.

    2012-04-01

    This paper presents a combined approach using both geophysical and geotechnical approaches to study and evaluate the subsurface strata near ground for sites suffering from faults and cracks. It demonstrates how both techniques can be utilized to gather useful information for design geotechnical engineers. The safe distance for construction close to a ground crack is mainly dependant on the subsurface stratification and the engineering properties of underlying soils or rocks. Other factors include the area geology and concepts of safety margins. This study is carried out for a site in Al-Qassim region, Saudi Arabia. This type of faults and cracks can normally occur due to a geological or physical event or due to the nature and properties of the subsurface material. The geotechnical works included advancing rotary boreholes to depths of 25m to 31m with sampling and testing. The geophysical method used included performing 2D electrical resistivity profiles. The results of geophysical and geotechnical works showed good and close agreement. The use of 2D electrical resistivity was found useful to establish the layer thicknesses of shale and highly plastic clay. This cannot be determined without deep and expensive direct boring investigation. The results showed that a thick layer of expansive soil, which is considered a high-risk soil type containing large percentage of highly plastic clay materials, underlies the site. The volume changes due to humidity variations can result in either swelling or shrinking. These changes can have significant impact on engineering structures such as light buildings and roads. The logic of placing structures in close vicinity of the cracks is based on lateral stresses exerted on the crack face. The layer thickness is a detrimental factor to establish a safe design distance. Stress distribution analysis procedure is explained.

  7. Basal keratinocytes contribute to all strata of the adult zebrafish epidermis.

    Science.gov (United States)

    Lee, Raymond T H; Asharani, P V; Carney, Thomas J

    2014-01-01

    The epidermis of terrestrial vertebrates is a stratified epithelium and forms an essential protective barrier. It is continually renewed, with dead corneocytes shed from the surface and replaced from a basal keratinocyte stem cell population. Whilst mouse is the prime model system used for epidermal studies, there is increasing employment of the zebrafish to analyse epidermis development and homeostasis, however the architecture and ontogeny of the epidermis in this system are incompletely described. In particular, it is unclear if adult zebrafish epidermis is derived entirely from the basal epidermal stem cell layer, as in the mouse, or if the most superficial keratinocyte layer is a remnant of the embryonic periderm. Furthermore, a relative paucity of cellular markers and genetic reagents to label and manipulate the basal epidermal stem cell compartment has hampered research. Here we show that the type I keratin, krtt1c19e, is a suitable marker of the basal epidermal layer and identify a krtt1c19e promoter fragment able to drive strong and specific expression in this cell type. Use of this promoter to express an inducible Cre recombinase allowed permanent labelling of basal cells during embryogenesis, and demonstrated that these cells do indeed generate keratinocytes of all strata in the adult epidermis. Further deployment of the Cre-Lox system highlighted the transient nature of the embryonic periderm. We thus show that the epidermis of adult zebrafish, as in the mouse, derives from basal stem cells, further expanding the similarities of epidermal ontogeny across vertebrates. Future use of this promoter will assist genetic analysis of basal keratinocyte biology in zebrafish.

  8. Analysis of Overlying Strata Movement and Behaviors in Caving and Solid Backfilling Mixed Coal Mining

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    Yanli Huang

    2017-07-01

    Full Text Available Based on techniques of close upper protective coal-rock layer mining, relieved gas extraction, and underground gangue washing-discharging-backfilling, this paper initiates the concept of mixed fully-mechanized coal mining, which combines a solid backfilling method and a caving method (hereinafter referred to as “backfill and caving mixed mining”. After the principle and key techniques are introduced, a physical simulation experiment and a numerical simulation are used to study the characteristics of the overlying strata’s fracture development, the main roof subsidence, the stress field and its influence area in the transition area with the length ratios of the backfilling section and the caving section, and the advancing distance of the mixed longwall face. Thus, the lengths of the caving section and the backfilling section, the parameters of the support system in the transition section, and the design process of the mixed longwall face are presented. In practice, the mixed longwall face Ji15-31010 in Ping-dingshan No. 12 Colliery proves that the designed lengths of 120 m and 100 m for the backfilling section and the caving section, respectively, are appropriate. The monitoring results of the hydraulic support working resistance show that the supports were working well in general; the maximum growth height of the overlying strata fracture is 18 m; the gas drainage efficiency is up to 80% and the average gas concentration is 0.1 g/m3; a large quantity of gangue generated in the Ji14 seam is disposed underground; coal and gas are extracted simultaneously; and significant environmental and economic benefits are realized.

  9. Nutrient-limited biodegradation of PAH in various soil strata at a creosote contaminated site.

    Science.gov (United States)

    Breedveld, G D; Sparrevik, M

    2000-01-01

    The effects of nutrient addition on the in situ biodegradation of polycyclic aromatic hydrocarbons in creosote contaminated soil were studied in soil columns taken from various soil strata at a wood preserving plant in Norway. Three samples were used: one from the topsoil (0-0.5 m), one from an organic rich layer (2-2.5 m) and one from the sandy aquifer (4.5-5 m). The addition of inorganic nitrogen and phosphorous stimulated the degradation of polycyclic aromatic hydrocarbons (PAHs) in the top soil and the aquifer sand. These two soils, which differed strongly in contamination levels, responded similarly to nutrient addition with the corresponding degradation of 4-ring PAHs. The ratio between available nitrogen (N) and phosphorous (P) might explain the degree of degradation observed for the 4-ring PAHs. However, the degree of degradation of 3-ring PAHs did not significantly increase after nutrient addition. An increase in the respiration rate, after nutrient addition, could only be observed in the topsoil. In the aquifer sand, 4-ring PAH degradation was not accompanied by an increase in the respiration rate or the number of heterotrophic micro-organisms. PAH degradation in the organic layer did not respond to nutrient addition. This was probably due to the low availability of the contaminants for micro-organisms, as a result of sorption to the soil organic matter. Our data illustrate the need for a better understanding of the role of nutrients in the degradation of high molecular weight hydrocarbons for the successful application of bioremediation at PAH contaminated sites.

  10. High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: depth- and strata-dependent spatial variability from rock-core sampling

    Science.gov (United States)

    Goode, Daniel J.; Imbrigiotta, Thomas E.; Lacombe, Pierre J.

    2014-01-01

    Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55 years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently

  11. Graptolite graveyard: Re-Os dating of macroplankton at the Lower-Middle Ordovician boundary (Floian-Dapingian stage boundary), Tøyen Shale, southern Sweden

    Science.gov (United States)

    Goswami, V.; Stein, H. J.; Hannah, J. L.; Ahlberg, P.; Maletz, J.

    2017-12-01

    There exist only 16 radiometric ages for the entire 42 m.y. Ordovician Period. Stage boundaries are biostratigraphically defined by the first appearance of agreed on graptolite and conodont species. Cosmopolitan graptolites are common in the Ordovician and their relatively brief stratigraphic durations make them ideal for global correlations. The Floian-Dapingian stage boundary (Lower-Middle Ordovician boundary) is very poorly constrained, with an absence of radiometric dates for several million years below the boundary and poor statistics on ages in the lower Dapingian [1]. Here we use the Ordovician Tøyen Shale, widespread across southern Sweden and Norway with a highly-refined graptolite biostratigraphy, to add a new age constraint [2]. With drill core from Lerhamn, Sweden (samples from 35.75-36.70 m depth), we employ a novel approach to directly date the fauna. We physically extracted a well-preserved 5-cm fossil of macroplankton (graptolite) from organic-rich shales (up to 4% TOC) for Re-Os dating. The graptolite and its hosting shale together define a well-constrained Model 1 isochron of 469.4 ± 1.7 Ma (2s, MSWD = 1.7, n = 9) and an initial 187Os/188Os (Osi) of 0.802 ± 0.002 for seawater. The Osi documents sustained radiogenic Os input to seawater from the Neoproterozoic-Cambrian through the Early Ordovician, in concert with the Sr isotope seawater curve. The analyzed graptolite belongs to the species Pseudophyllograptus augustifolius, a member of the upper Floian fauna [2]. Our nominal age for the dated graptolite and the shale is lower Dapingian according to the 2017 GTS [1]. Therefore, the Re-Os age suggests the Floian-Dapingian stage boundary may be younger than currently accepted. As defined in the GTS, the Dapingian stage is only 2.7 m.y. (470.0 ± 1.4 to 467.3 ± 1.1 Ma); combined uncertainties could give the Dapingian a mere 0.2 m.y. duration (or a maximum of 5 m.y). Although uncertainties overlap, our first dating of the Lower-Middle Ordovician

  12. PENENTUAN TITIK-TITIK BATAS OPTIMUM STRATA PADA PENARIKAN CONTOH ACAK BERLAPIS DENGAN PEMROGRAMAN DINAMIK (Kasus : Pengeluaran per Kapita Propinsi Jawa Timur Tahun 2008

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    Mahyudi Mahyudi

    2015-06-01

    Full Text Available Optimum stratification is the method of choosing the best boundaries that make strata internally homogeneous, given some sample allocation. In order to make the strata internally homogenous, the strata should be constructed in such a way that the strata variances for the characteristic under study be as small as possible. This could be achieved effectively by having the distribution of the main study variable known and create strata by cutting the range of the distribution at suitable points. The problem of finding Optimum Strata Boundaries (OSB is considered as the problem of determining Optimum Strata Widths (OSW. The problem is formulated as a Mathematical Programming Problem (MPP, which minimizes the variance of the estimated population parameter under Neyman allocation subject to the restriction that sum of the widths of all the strata is equal to the total range of the distribution. The distributions of the study variable are considered as continuous with standard normal density functions. The formulated MPPs, which turn out to be multistage decision problems, can then be solved using dynamic programming technique proposed by Bühler and Deutler (1975. After the counting process using C++ program received the width of each stratum. From these results the optimal boundary point can be determined for each stratum. For the two strata to get the optimal point on the boundary x1 = 0.002. For the formation of three strata obtained the optimal point on the boundary x1 = -0.546 and x2 = 0.552. For the formation of four strata obtained optimal boundary point is x1 = -0.869, x2 = 0.003 and x3 = 0.878. In forming five strata obtained optimal boundary point x1 = -1.096, x2 = -0.331, x3 = 0.339 and x4 = 1.107. The establishment of a total of six strata obtained the optimal point on the boundary x1 = -1.267, x2 = -0.569, x3 = 0.005, x4 = 0.579 and x5 = 1.281.

  13. Observation measurement and analysis on strata pressure of fully mechanized longwall caving face in special thick seam

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.; Wu, J.; Li, B.; Liu, S.; Liang, J. [China University of Mining and Technology (China). Beijing Graduate School

    1997-09-01

    This paper introduces a fully mechanized longwall caving mining face in Weijiadi Mine, Gansu Province. The seam to be mined was a special thick seam with potential outbursts of coal and gas and spontaneous combustion. The average thickness of the seam was 12 m. The seam was mined with a one-pass method. Due to the softness of the coal body and the roof and floor, the strata support and bearing area of the coal face had to be moved in advance, slowly when the gateways became seriously deformed. The slow advancing had provided a condition for the spontaneous combustion of the residual coal in the goaf. Through observation, measurement and analysis of the strata in the coal face; the results revealed a rational support with hydraulic powered supports mainly to control the roof and the coal face, the distance of the periodical strata pressure was 20 to 35 m. The support resistance of the one-pass caving face was higher than the slicing mining face. The conveyor gateway of the caving face was seriously deformed and an advanced support of the gateway should have been made. 6 figs.

  14. Yellow-tailed woolly monkey (Lagothrix flavicauda) proximal spacing and forest strata use in La Esperanza, Peru.

    Science.gov (United States)

    Shanee, Sam

    2014-10-01

    Inter-individual spacing of primates and their use of forest strata depend on temporal and spatial changes in the environment and on predator avoidance, group demography, and social conditions. Greater proximity also increases the chances of agonistic and affinitive contact between individuals. I collected behavioral data for three groups of yellow-tailed woolly monkeys (Lagothrix flavicauda) by instantaneous sampling of focal animals for 15 months in La Esperanza, northeastern Peru. By use of combined data for all groups I examined the effects of season, activity, and age/sex class on nearest-neighbor distances and forest strata use. Small differences were observed for nearest-neighbor distances, forest strata use by different age/sex classes, and activity. Adult males had the lowest contact index scores. Contact index scores were low for juvenile females, for which nearest-neighbor distances were largest. Very little aggressive behavior was observed. Focal animals preferred upper levels of the forest with little difference in height for different activities. Lagothrix flavicauda have very cohesive groups with little seasonal or activity-dependent difference between nearest-neighbor distances or proximity. These results suggest that this species has less variable social organization and greater group cohesion than other Atelini. However, more studies are needed on other populations of L. flavicauda to better determine the species' social organization. Studies are also required to determine the extent to which dispersal times and kinship affect proximity, nearest-neighbor distances, and aggression.

  15. Sequence stratigraphic analysis of Eocene Rock Strata, Offshore Indus, southwest Pakistan

    Science.gov (United States)

    Khan, Natasha; Rehman, Khaista; Ahmad, Sajjad; Khokher, Jamil; Hajana, M. Iqbal; Hanif, M.

    2016-09-01

    In this study, seismic data from two wells (Pak G2-1 and Indus Marine-1C) and age diagnostic larger benthic foraminifera (LBF) within drill cuttings has been used for the first time to identify depositional sequences within the carbonates in the Offshore Indus Basin, Pakistan. The Offshore Indus is tectonically categorized as a passive continental margin where carbonates occur as shelf carbonates in the near offshore and on volcanic seamounts in deeper waters. Seismic data analysis has indicated the presence of minor faults and carbonate buildups above the igneous basement in the south. Patterns of the seismic reflections enabled definition of three seismic facies units identified as: Unit 1 basement, represented by chaotic, moderate amplitude reflection configuration; while parallel bedding and the drape of overlying strata is typical character of Unit 2, carbonate mound facies. The younger Miocene channels represent Unit 3. The diagnosis of Alveolina vredenburgi/cucumiformis biozone confirmed the Ilerdian (55-52 Ma) stage constituting a second order cycle of deposition for the Eocene carbonates (identified as Unit 2). The carbonate succession has been mainly attributed to an early highstand system tract (HST). The environmental conditions remained favorable leading to the development of keep-up carbonates similar to pinnacle buildups as a result of aggradation during late transgressive system tract and an early HST. The carbonate sequence in the south (Pak G2-1) is thicker and fossiliferous representing inner to middle shelf depths based on fauna compared to the Indus Marine-1C in the north, which is devoid of fossils. Three biozones (SBZ 5, SBZ 6 and SBZ 8) were identified based on the occurrence of LBF. The base of the SBZ 5 zone marks the larger foraminifera turnover and the Paleocene-Eocene (P-E) boundary. The LBF encountered in this study coincides with earlier findings for the P-E boundary. Our findings indicate that the entire Ilerdian stage ranges from 55

  16. Natural gas exploration prospect in the Upper Paleozoic strata, NW Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Hao Shen

    2016-12-01

    Full Text Available Progress of natural gas exploration has recently been made in the Upper Paleozoic marine-facies reservoirs in the NW Sichuan Basin. It has been proved that the Middle Permian Qixia Fm pore-type dolomite reservoirs may be distributed continuously in a large area, besides, for the first time favorable gas-bearing Devonian dolomite reservoirs in great thickness were discovered in the downhole there. Recent research achievements indicate that: (1 The Lower Cambrian quality source rocks in huge thickness were found in the study sedimentary area with advantageous hydrocarbon source conditions. (2 Influenced by the Caledonian movement, the whole NW Sichuan Basin was lifted up to form a massive box-like NS-trending plunging uplift low steep in the west but high sluggish in the east, laying a robust foundation for the inheritance of Devonian, Carboniferous, and Permian platform margin reef large-scale sedimentation and dolomitization. (3 In the Upper Paleozoic strata, there were multiple planes of unconformity and multi-stage supergene karst occurred, improving the preservation and seeping capacity of reservoirs. (4 Tectonic deformations resulted from the nappe structure in the Longmenshan Mountain provided good hydrocarbon source fractures and sealing conditions for oil and gas reservoirs, which is conductive to the formation of a giant gas pool. It is concluded that the back-thrust anticline belt east to Hidden fault I in this study area has favorable conditions for large-scale structural–stratigraphic and structural–lithologic combination traps. As suggested in this study, relatively strong dolomitization was found in the Qixia Fm in the Shejianhe River–Zhongba higher palaeogeomorphic deposit area, so the most favorable exploration target of the Qixia Fm will be around the central axis of Caledonian paleo-uplift to the east ridgeline, and the most favorable prospect of the Upper Palaeozoic will be the central axis to the west of Hidden fault I

  17. 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.

  18. 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

  19. Water-quality assessment of the Cambrian-Ordovician aquifer system in the northern Midwest, United States

    Science.gov (United States)

    Wilson, John T.

    2012-01-01

    This report provides a regional assessment of groundwater quality of the Cambrian-Ordovician aquifer system, based primarily on raw water samples collected by the NAWQA Program during 1995 through 2007. The NAWQA Program has published findings in local study-unit reports encompassing parts of the Cambrian-Ordovician aquifer system. Data collected from the aquifer system were used in national synthesis reports on selected topics such as specific water-quality constituent classes, well type, or aquifer material; however, a synthesis of groundwater quality at the principal aquifer scale has not been completed and is therefore the major purpose of this report. Water samples collected by the NAWQA Program were analyzed for various classes of characteristics including physical properties, major ions, trace elements, nutrients and dissolved organic carbon, radionuclides (tritium, radon, and radium), pesticides, and volatile organic compounds. Subsequent sections of this report provide discussions on these classes of characteristics. The assessment objectives of this report are to (1) summarize constituent concentrations and compare them to human-health benchmarks and non-health guidelines; (2) determine the geographic distribution of constituent concentrations and relate them to various factors such as confining conditions, well type, land use, and groundwater age; and (3) evaluate near-decadal-scale changes in nitrate concentrations and pesticide detections. The most recent sample collected from each well by the NAWQA Program was used for most analyses. Near-decadal-scale changes in nitrate concentrations and pesticide detections were evaluated for selected well networks by using the most recent sample from each well and comparing it to the results from a sample collected 7 or 11 years earlier. Because some of the NAWQA well networks provide a limited areal coverage of the aquifer system, data for raw water samples from other USGS sources and state agencies were included

  20. Large-magnitude Middle Ordovician volcanic ash falls in North America and Europe: Dimensions, emplacement and post-emplacement characteristics

    Science.gov (United States)

    Huff, W.D.; Kolata, Dennis R.; Bergstrom, Stig M.; Zhang, Y.-S.

    1996-01-01

    Middle Ordovician K-bentonites represent some of the largest known fallout ash deposits in the Phanerozoic Era. They cover minimally 2.2 ?? 106 km2 in eastern North America and 6.9 ?? 105 km2 in northwestern Europe, and represents the coeval accumulation of plinian and co-ignimbrite ash on both Laurentia and Baltica during the closure of the Iapetus Ocean. The three most widespread beds are the Deicke and Millbrig K-bentonites in North America and the Kinnekulle K-bentonite in northwestern Europe. The vents were located near the Laurentian margin of Iapetus on an arc or microplate undergoing collision with Laurentia. The volume of ash preserved in the stratigraphic record converted to dense rock equivalent (DRE) of silicic magma is minimally estimated to be 943 km3 for the Deicke, 1509 km3 for the Millbrig and 972 km3 for the Kinnekulle. The Millbrig and Kinnekulle beds are coeval and possibly equivalent, yielding a combined DRE volume of nearly 2500 km3. Some unknown but probably large amount of additional ash fell into oceanic regions of the Iapetus, but these areas became subducted and the ash is not preserved in the geologic record. The symmetry of the thickness contours is suggestive that one or more ash clouds interacting with equatorial stratospheric and tropospheric wind patterns dispersed pyroclastic material to both the northwest and southeast in terms of Ordovician paleogeography. Based on grain size measurements and thickness/area1/2 plots we conclude the three beds were each formed from co-ignimbrite or possibly phreatoplinian eruption columns. Analyses of melt inclusions in primary quartz crystals indicate the parental magma contained approximately 4% dissolved water at the time of the eruption. This water provided the explosive energy during the initial gas thrust phase. The implied fragmentation pressure on the magma would have reduced much of the ejecta to small particles, forming a deposit composed largely of single crystals and glassy dust

  1. Age and geochemistry of the Charlestown Group, Ireland: Implications for the Grampian orogeny, its mineral potential and the Ordovician timescale

    Science.gov (United States)

    Herrington, Richard J.; Hollis, Steven P.; Cooper, Mark R.; Stobbs, Iain; Tapster, Simon; Rushton, Adrian; McConnell, Brian; Jeffries, Teresa

    2018-03-01

    Accurately reconstructing the growth of continental margins during episodes of ocean closure has important implications for understanding the formation, preservation and location of mineral deposits in ancient orogens. The Charlestown Group of county Mayo, Ireland, forms an important yet understudied link in the Caledonian-Appalachian orogenic belt located between the well documented sectors of western Ireland and Northern Ireland. We have reassessed its role in the Ordovician Grampian orogeny, based on new fieldwork, high-resolution airborne geophysics, graptolite biostratigraphy, U-Pb zircon dating, whole rock geochemistry, and an examination of historic drillcore from across the volcanic inlier. The Charlestown Group can be divided into three formations: Horan, Carracastle, and Tawnyinah. The Horan Formation comprises a mixed sequence of tholeiitic to calc-alkaline basalt, crystal tuff and sedimentary rocks (e.g. black shale, chert), forming within an evolving peri-Laurentian affinity island arc. The presence of graptolites Pseudisograptus of the manubriatus group and the discovery of Exigraptus uniformis and Skiagraptus gnomonicus favour a latest Dapingian (i.e. Yapeenian Ya 2/late Arenig) age for the Horan Formation (equivalent to c. 471.2-470.5 Ma according to the timescale of Sadler et al., 2009). Together with three new U-Pb zircon ages of 471.95-470.82 Ma from enclosing felsic tuffs and volcanic breccias, this fauna provides an important new constraint for calibrating the Middle Ordovician timescale. Overlying deposits of the Carracastle and Tawnyinah formations are dominated by LILE- and LREE-enriched calc-alkaline andesitic tuffs and flows, coarse volcanic breccias and quartz-feldspar porphyritic intrusive rocks, overlain by more silicic tuffs and volcanic breccias with rare occurrences of sedimentary rocks. The relatively young age for the Charlestown Group in the Grampian orogeny, coupled with high Th/Yb and zircon inheritance (c. 2.7 Ga) in intrusive

  2. Iodine-129 chronological study of brines from an Ordovician paleokarst reservoir in the Lunnan oilfield, Tarim Basin

    International Nuclear Information System (INIS)

    Chen, Jian; Liu, Dayong; Peng, Ping'an; Ning, Chen; Xiaolin, Hou; Baoshou, Zhang; Zhongyao, Xiao

    2016-01-01

    Previous studies have shown that brines in an Ordovician paleokarst reservoir of the Lunnan oilfield in the Tarim Basin, China, are the product of mixing of paleo-evaporated seawater in the east with paleometeoric waters in the west. In order to put time constraints on the brine and related hydrocarbons in this field, 10 brine samples were collected, for which the iodine concentrations and 129 I/I ratios were measured and discussed. The iodine concentration (3.70–31.2 mg/L) and the 129 I/I ratio (189–897 × 10 −15 ) show that the iodine in the paleoseawater and meteoric water (MW) had different origins and 129 I characteristics. The paleoseawater has a high iodine content (∼31 mg/L), indicating that iodine was introduced into the reservoir along with thermally generated hydrocarbons, possibly in the Cretaceous, from the Caohu Sag in the eastern area. Based on consideration of all possible origins of iodine and 129 I in the brines, it is suggested that the meteoric water maintained its initial iodine content (0.01 mg/L) and 129 I/I ratio (1500 × 10 −15 ), whereas the iodine-enriched paloseawater (IPSW) exhibited a secular 129 I equilibrium (N sq  = 39 atom/μL) as a result of fissiogenic 129 I input in the reservoir over a long period of time. The model of brine evolution developed on that basis confirmed that meteoric water entered the reservoir in the Miocene at about 10 Ma, and partially mixed with the iodine-enriched paleoseawater. The movement of meteoric water was facilitated by faults created during the Himalayan orogeny, then became more dense after dissolving Paleogene halite and infiltrated into the reservoir at high pressure. The iodine and 129 I concentration in the brine contains information about the path and history of the fluid in the reservoir. This may be useful in oil exploration, since the movement of water was, to some extent, related to hydrocarbon migration. - Highlights: • A 129 I chronological study of deep oilfield

  3. Strata control in tunnels and an evaluation of support units and systems currently used with a view to improving the effectiveness of support stability and safety of tunnels.

    CSIR Research Space (South Africa)

    Haile, AT

    1995-12-01

    Full Text Available This project report addresses the issue of strata control in tunnel excavations with the aim of improving the stability of the excavation through improved design methodologies and support systems....

  4. Results of geochemical and mineralogical studies on uranium in Zechstein copper-bearing strata from Lubin-Polkowice area

    International Nuclear Information System (INIS)

    Bareja, E.

    1977-01-01

    The paper presents the results of geochemical and mineralogical studies on uranium in Zechstein copper-bearing strata from the Lubin-Polkowice area. It was found that particular lithofacial varietes of Zechstein copper-bearing strata are characterized by different concentration of uranium. The mineralogical studies made possible determination of the nature of uranium mineralization and the interdependence between uranium and lithology of copper-bearing strata. An interesting uranium mineralization was found in tectonic breccias which yield black blende and schroeckingerite as well as calcite, gypsum, pyrite, hematite and geothite. Secondary minerals such as schroeckingerite and geothite evidence intense weathering processes acting in the copper deposit. The highest value of geochemical background of uranium in the copper-bearing series is displayed by basel copper-bearing shales (so called pitch-black shales) - 68.10 x 10 -40 /0 U. Statistical distribution of that element is unimodal. Distribution of uranium is polymodal in basal sandstones of the copper-bearing series. The geochemical background of red-coloured sandstones (Rotliegendes) is low, equalling 0.39 x 10 40 /0 U, whilst that of gray-coloured sandstones (Zechstein) - 2.32 x 10 -40 /0 U. An anomallous population (344.0 x 10 -40 /0 U) found in the case of gray sandstones of the Lubin-Polkowice area evidences the effects of secondary processes on concentration of uranium. In sandstones occur black blende, carburanes as well as calcite, hematite and goethite. A bimodal distribution of uranium was found in carbonate series. Limestones are characterized by low value of geochemical background (Dsub(x1) = 0.78 x 10 -40 /0 U) whilst dolomites by markedly higher values of the background (Dsub(x2) = 2.73 x 10 -40 /0 U). (author)

  5. Seasonal variation of molluscan assemblages in different strata of photophilous algae in the Alboran Sea (western Mediterranean)

    Science.gov (United States)

    Urra, J.; Rueda, J. L.; Mateo Ramírez, Á.; Marina, P.; Tirado, C.; Salas, C.; Gofas, S.

    2013-10-01

    The seasonal dynamics of molluscan assemblages inhabiting the algal fronds and the underlying sediment of photophilous algae were analyzed in NW Alboran Sea between July 2007 and April 2008. Molluscs were sampled using SCUBA in two different algal stands (7 km apart) dominated by the brown algae Stypocaulon scoparium, and following an inter-strata sampling protocol consisting in first sampling the algal fronds and then the underlying substratum. The studied algal stands harbored a highly biodiverse malacofauna, with 193 species identified. Assemblages on algal fronds and sediment displayed significant seasonal variations, being more apparent on the fronds, with maximum species richness, abundance and Shannon-Wiener diversity values in summer in both strata. The between-strata differences were also observed in the trophic structure of the assemblages: algal fronds were quantitatively dominated by microalgae or periphyton grazers and the sediment by detritivores and plankton and seston feeders. The high dominance of some species resulted in lower values of diversity and evenness in autumn in the sediment (e.g. Nodulus contortus and Bittium reticulatum) and in spring on the fronds (e.g. Rissoa guerinii and Musculus costulatus). The seasonal variability of the assemblages was mainly related to the population dynamics of dominant species (22 spp. displaying dominance values > 1%) (i.e. recruitment events, high mortality rates of juveniles and/or migrations among habitats). Other factors analyzed were (1) the vegetative cycle of algae, which played an important role in the abundance of some dominant epifaunal grazers, with high abundance and species richness values coinciding with high biomass of algae; and (2) the percentage of organic matter in the sediment, which was related to the abundance changes of some depositivores species. Further conservation strategies for macroalgal stands should be taken into consideration, as this type of photophilous habitat harbors rich

  6. Interpreting Fracture Patterns in Sandstones Interbedded with Ductile Strata at the Salt Valley Anticline, Arches National Park, Utah; TOPICAL

    International Nuclear Information System (INIS)

    LORENZ, JOHN C.; COOPER, SCOTT P.

    2001-01-01

    Sandstones that overlie or that are interbedded with evaporitic or other ductile strata commonly contain numerous localized domains of fractures, each covering an area of a few square miles. Fractures within the Entrada Sandstone at the Salt Valley Anticline are associated with salt mobility within the underlying Paradox Formation. The fracture relationships observed at Salt Valley (along with examples from Paleozoic strata at the southern edge of the Holbrook basin in northeastern Arizona, and sandstones of the Frontier Formation along the western edge of the Green River basin in southwestern Wyoming), show that although each fracture domain may contain consistently oriented fractures, the orientations and patterns of the fractures vary considerably from domain to domain. Most of the fracture patterns in the brittle sandstones are related to local stresses created by subtle, irregular flexures resulting from mobility of the associated, interbedded ductile strata (halite or shale). Sequential episodes of evaporite dissolution and/or mobility in different directions can result in multiple, superimposed fracture sets in the associated sandstones. Multiple sets of superimposed fractures create reservoir-quality fracture interconnectivity within restricted localities of a formation. However, it is difficult to predict the orientations and characteristics of this type of fracturing in the subsurface. This is primarily because the orientations and characteristics of these fractures typically have little relationship to the regional tectonic stresses that might be used to predict fracture characteristics prior to drilling. Nevertheless, the high probability of numerous, intersecting fractures in such settings attests to the importance of determining fracture orientations in these types of fractured reservoirs

  7. Lithofacies paleogeography mapping and reservoir prediction in tight sandstone strata: A case study from central Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Yuan Zhong

    2017-09-01

    Full Text Available Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to traditional lithofacies paleogeography mapping. Therefore, the prediction of reservoir sweet spots has remained problematic in the field of petroleum exploration. This study provides new insight into resolving this problem, based on the analyses of depositional characteristics of a typical modern sand-rich formation in a shallow braided river delta of the central Sichuan Basin, China. The varieties of sand-rich strata in the braided river delta environment include primary braided channels, secondary distributary channels and the distribution of sediments is controlled by the successive superposed strata deposited in paleogeomorphic valleys. The primary distributary channels have stronger hydrodynamic forces with higher proportions of coarse sand deposits than the secondary distributary channels. Therefore, lithofacies paleogeography mapping is controlled by the geomorphology, valley locations, and the migration of channels. We reconstructed the paleogeomorphology and valley systems that existed prior to the deposition of the Xujiahe Formation. Following this, rock-electro identification model for coarse skeletal sand bodies was constructed based on coring data. The results suggest that skeletal sand bodies in primary distributary channels occur mainly in the valleys and low-lying areas, whereas secondary distributary channels and fine deposits generally occur in the highland areas. The thickness distribution of skeletal sand bodies and lithofacies paleogeography map indicate a positive correlation in primary distributary channels and reservoir thickness. A significant correlation exists between different sedimentary facies and petrophysical properties. In addition, the degree of reservoir development in different sedimentary facies

  8. The Siljan Ring in central Sweden - a window into the Palaeozoic history of Baltoscandia

    Science.gov (United States)

    Lehnert, O.; Meinhold, G.; Bergström, S. M.; Calner, M.; Ebbestad, J. O. R.; Egenhoff, S.; Frisk, Å. M.; Högström, A. E. S.; Maletz, J.

    2012-04-01

    The Siljan meteorite crater, the largest known impact crater in Europe, is a main target of the research project 'Concentric Impact Structures in the Palaeozoic (CISP)', an integral of the Swedish Deep Drilling Program (SDDP). A set of new drillcores now provides possibilities to document the associated Early Palaeozoic sedimentary strata that form the crater ring-structure. In 2011 our research team has sampled the core sections for carbon isotope chemostratigraphy, thermal maturity analysis, sediment provenance, facies and microfacies studies. A dug trench at Nittsjö in the south-eastern part of the ring-structure forms complement to the drillcores and the total data set will allow intra- and intercontinental correlation of the succession and help to reconstruct Caledonian tectonic movements in the region. Based on initial analysis of the core sections, the Palaeozoic succession starts with the Tremadocian Obolus conglomerate whereas the youngest pre-Caledonian strata are Mid-Silurian shales of the Nederberga Formation. Our first preliminary studies show that different, and yet undefined, facies belts are preserved in the Siljan District. This part of Sweden, previously regarded to represent a stable cratonic area unaffected by the Caledonian collision between Baltica and Laurentia, locally has a complex tectonic history. In the western part of the crater, the Lower to Middle Ordovician carbonate succession is about 21 m thick, with a sharp flooding surface on top of the Mid-Ordovician Holen Formation. The immediately overlying shales are of upper Llandovery age based on graptolite data and comprises a minimum thickness of about 224 m. The erosional unconformity and substantial hiatus between these units suggest an extended period of uplift and erosion, presumably related to forebulge migration towards the east due to tectonic loading by the Caledonian nappes to the west. Megaslumps, debris flows, turbidites and several synsedimentary tectonic features in the

  9. Mechanism of rigid overlaying of carboniferous strata failure in face mining in the case of multiseams deposit

    Czech Academy of Sciences Publication Activity Database

    Jiránková, E.; Staš, Lubomír; Kajzar, Vlastimil; Doležalová, Hana

    2013-01-01

    Roč. 10, č. 2 (2013), s. 189-195 ISSN 1214-9705 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MV VG20102014034 Institutional support: RVO:68145535 Keywords : subsidence trough * rock mass * overlaying strata * longwall mining * tensor stress measurement Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 0.667, year: 2013 http://www.irsm.cas.cz/materialy/acta_content/2013_02/acta_170_08_Jirankova_189-195.pdf

  10. 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

  11. Kärdla (Hiiumaa Island, Estonia)—the buried and well-preserved Ordovician marine impact structure

    Science.gov (United States)

    Suuroja, Kalle; Suuroja, Sten; All, Tarmo; Floden, Tom

    The Kärdla marine impact structure (Estonia, 58°58'N, 22°46'E) was formed at 455 Ma (Upper Ordovician), in a shallow epicontinental sea some tens of kilometres from the land and erosion area. The iron-rich projectile about 200 m in diameter approached from the west at an angle of 30-45°. The impactor penetrated about 50-m-thick water layer and the sedimentary cover and exploded in the uppermost part of the crystalline basement. A complex crater, 4 km wide and about 500 m deep, with a central uplift rising 130 m from the crater floor, was formed. The highest point of the rimwall is 110 m above the target level. The rimwall is cut by at least two resurge-excavated gullies. The variable height of the rimwall obviously results from the obliqueness of the impact. Outside the crater an elliptical area was revealed, 12-15 km in diameter, with deformed sedimentary rocks below the target level. The elliptical shape of this area may also be due to the oblique impact. Because the crater and its surroundings were buried directly after the impact, the whole complex of impact-related sediments is preserved there. They are recovered by 160 wells, six of which penetrate the entire complex of impact breccias inside the crater.

  12. Stratigraphic Interpretation and Reservoir Implications of the Arbuckle Group (Cambrian-Ordovician) using 3D Seismic, Osage County, Oklahoma

    Science.gov (United States)

    Keeling, Ryan Marc

    The Arbuckle Group in northeastern Oklahoma consists of multiple carbonate formations, along with several relatively thin sandstone units. The group is a part of the "Great American Carbonate Bank" of the mid-continent and can be found regionally as far east as the Arkoma Basin in Arkansas, and as far west as the Anadarko Basin in Oklahoma. The Arbuckle is part of the craton-wide Sauk sequence, which is both underlain and overlain by regional unconformities. Arbuckle is not deposited directly on top of a source rock. In order for reservoirs within the Arbuckle to become charged with hydrocarbons, they must be juxtaposed against source rocks or along migration pathways. Inspired by the petroleum potential of proximal Arbuckle reservoirs and the lack of local stratigraphic understanding, this study aims to subdivide Arbuckle stratigraphy and identify porosity networks using 3D seismic within the study area of western Osage County, Oklahoma. These methods and findings can then be applied to petroleum exploration in Cambro-Ordovician carbonates in other localities. My research question is: Can the Arbuckle in SW Osage County be stratigraphically subdivided based on 3D seismic characteristics? This paper outlines the depositional environment of the Arbuckle, synthesizes previous studies and examines the Arbuckle as a petroleum system in Northeastern Oklahoma. The investigation includes an interpretation of intra-Arbuckle unconformities, areas of secondary porosity (specifically, sequence boundaries), and hydrocarbon potential of the Arbuckle Group using 3D seismic data interpretation with a cursory analysis of cored intervals.

  13. Geomechanical behaviour of laminated, weak coal mine roof strata and the implications for a ground reinforcement strategy

    Energy Technology Data Exchange (ETDEWEB)

    Hebblewhite, B.K.; Lu, T. [University of New South Wales, Sydney, NSW (Australia). School of Mining Engineering

    2004-01-01

    This paper describes a component of the results from an ARC-SPIRT funded collaborative research project between UNSW, Powercoal Pty Ltd. and Springvale Coal Pty Ltd. The research project was aimed at identifying strategies for appropriate ground control in particularly weak and soft roof strata in underground coal mining. A field investigation was undertaken at Angus Place Colliery in the Western Coalfield of New South Wales. The investigation incorporated a range of geotechnical instrumentation and was conducted over a period of time from the development face until the site was lost into the goaf of a retreating longwall panel. This paper describes the outcomes from the field investigation, together with a selection of supporting laboratory studies. The paper also presents a number of alternative presentation modes for extensometry data. The results clearly demonstrate the time and face-proximity related influences on roof integrity, and particularly demonstrated the distribution of deformation, bed separation and strata failure into the roof and across the full span of the roadway, together with reflection of this behaviour within the fully encapsulated roof bolt reinforcement system installed.

  14. Methane Flux and Authigenic Carbonate in Shallow Sediments Overlying Methane Hydrate Bearing Strata in Alaminos Canyon, Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Joseph P. Smith

    2014-09-01

    Full Text Available In June 2007 sediment cores were collected in Alaminos Canyon, Gulf of Mexico across a series of seismic data profiles indicating rapid transitions between the presence of methane hydrates and vertical gas flux. Vertical profiles of dissolved sulfate, chloride, calcium, magnesium, and dissolved inorganic carbon (DIC concentrations in porewaters, headspace methane, and solid phase carbonate concentrations were measured at each core location to investigate the cycling of methane-derived carbon in shallow sediments overlying the hydrate bearing strata. When integrated with stable carbon isotope ratios of DIC, geochemical results suggest a significant fraction of the methane flux at this site is cycled into the inorganic carbon pool. The incorporation of methane-derived carbon into dissolved and solid inorganic carbon phases represents a significant sink in local carbon cycling and plays a role in regulating the flux of methane to the overlying water column at Alaminos Canyon. Targeted, high-resolution geochemical characterization of the biogeochemical cycling of methane-derived carbon in shallow sediments overlying hydrate bearing strata like those in Alaminos Canyon is critical to quantifying methane flux and estimating methane hydrate distributions in gas hydrate bearing marine sediments.

  15. Arc petrogenesis in southern Ireland and the Isle of Man: Implications for Ordovician accretionary history and constraints from Late Caledonian plutonism

    Science.gov (United States)

    Fritschle, Tobias; Daly, J. Stephen; Whitehouse, Martin J.; McConnell, Brian; Buhre, Stephan

    2016-04-01

    Peri-Laurentian and peri-Gondwanan magmatic arcs and microcontinents, and their attendant sedimentary basins were assembled during the Caledonian Orogeny (c. 490 - 400 Ma) to form the Irish and British lithosphere. Accretion of these terranes to Laurentia and subsequent closure of the Iapetus Ocean initiated the generation of widespread Late Caledonian plutons (c. 425 - 400 Ma). Petrogenetic investigation of Ordovician arc-related rocks aims to test possible terrane affinities, using geochemical data from the arcs and related rocks as well as isotopic signatures preserved within Late Caledonian granites. SIMS zircon U-Pb geochronology has provided middle to early Ordovician ages for volcanic rocks with arc affinities from Avoca (Ireland, c. 463 Ma) and a newly discovered volcanic sequence from Port-e-Vullen (Isle of Man, c. 473 Ma). Granitic rocks from Leinster (Ireland), interpreted as arc plutons, yielded late to middle Ordovician ages of c. 457 - 454 Ma (Croghan Kinshelagh) and c. 462 - 459 Ma (Graiguenamanagh), similar to the c. 457 Ma age of the Dhoon Granite (Isle of Man). Oxygen isotopic compositions of zircons from the Ordovician volcanic and plutonic rocks are close to or slightly heavier than mantle values (δ18O generally < 7 ‰). Lu-Hf zircon compositions suggest different terrane affinities: relatively juvenile ɛHfT values (c. +8.5 - +5.3) for the Avoca volcanics are similar to those of the older unit of the Croghan Kinshelagh Granite, whereas the Port-e-Vullen volcanics and the Graiguenamanagh Granite have less radiogenic ɛHfT values (c. +4.4 - +1.3). The present-day geographic distribution of these rocks and petrogenetic inferences from their North American correlatives invite comparison with the Avalonian and the Ganderian microcontinent, respectively[1]. These constraints are supported by inherited zircons and corresponding isotopic analyses. ɛHfT values (c. +11.5 - +1.5) from magmatic zircons of the Dhoon Granite and the younger unit of the

  16. 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

  17. Outcrops, Fossils, Geophysical Logs, and Tectonic Interpretations of the Upper Cretaceous Frontier Formation and Contiguous Strata in the Bighorn Basin, Wyoming and Montana

    Science.gov (United States)

    Merewether, E.A.; Cobban, W.A.; Tillman, R.W.

    2010-01-01

    In the Bighorn Basin of north-central Wyoming and south-central Montana, the Frontier Formation of early Late Cretaceous age consists of siliciclastic, bentonitic, and carbonaceous beds that were deposited in marine, brackish-water, and continental environments. Most lithologic units are laterally discontinuous. The Frontier Formation conformably overlies the Mowry Shale and is conformably overlain by the Cody Shale. Molluscan fossils collected from outcrops of these formations and listed in this report are mainly of marine origin and of Cenomanian, Turonian, and Coniacian ages. The lower and thicker part of the Frontier in the Bighorn Basin is of Cenomanian age and laterally equivalent to the Belle Fourche Member of the Frontier in central Wyoming. Near the west edge of the basin, these basal strata are disconformably overlain by middle Turonian beds that are the age equivalent of the Emigrant Gap Member of the Frontier in central Wyoming. The middle Turonian beds are disconformably overlain by lower Coniacian strata. Cenomanian strata along the south and east margins of the basin are disconformably overlain by upper Turonian beds in the upper part of the Frontier, as well as in the lower part of the Cody; these are, in turn, conformably overlain by lower Coniacian strata. Thicknesses and ages of Cenomanian strata in the Bighorn Basin and adjoining regions are evidence of regional differential erosion and the presence of an uplift during the early Turonian centered in northwestern Wyoming, west of the basin, probably associated with a eustatic event. The truncated Cenomanian strata were buried by lower middle Turonian beds during a marine transgression and possibly during regional subsidence and a eustatic rise. An uplift in the late middle Turonian, centered in north-central Wyoming and possibly associated with a eustatic fall, caused the erosion of lower middle Turonian beds in southern and eastern areas of the basin as well as in an adjoining region of north

  18. Preliminary report on the Oldenburg “butter shale” in the Upper Ordovician (Katian; Richmondian Waynesville Formation, USA

    Directory of Open Access Journals (Sweden)

    Christopher D. Aucoin

    2015-02-01

    Full Text Available The Cincinnatian Series (Upper Ordovician; upper Katian of the Cincinnati Arch region, Ohio, Indiana and Kentucky contains several bed packages informally referred to as “butter shales” or “trilobite shales”. These packages are typically 1–2 m of relatively pure, homogeneous claystone with isolated, lenticular limestone beds. These claystones are most widely known for their excellent preservation of abundant trilobites, especially Isotelus and Flexicalymene, as well as diverse and commonly articulated bivalves, and nautiloids. A newly recognized butter shale interval in the Clarksville Member of the Waynesville Formation contains a typical butter-shale fossil assemblage, dominated by bivalves, orthoconic cephalopods and trilobites. To better study the fabric of this claystone, a large, epoxy-coated block of the claystone was dry-cut. Polished surfaces show a variety of otherwise cryptic features, including pervasive bioturbation and the presence of probable lingulid escape burrows (Lingulichnus, as well as abundant fodinichnia (Chondrites, Planolites, Teichichnus. Preservation of articulated trilobites and closed bivalves in approximate living position, as well as escape burrows, indicates deposition as a series of mud burial events or obrution deposits. We suggest that the butter shales resulted from net accumulation of multiple episodes of re-suspended mud deposition, which rapidly smothered organisms and resulted in exceptional preservation. Between events the seafloor was colonized by abundant deposit-feeding infaunal organisms, which destabilized the substrate and generated turbidity near the sediment–water interface, thus inhibiting sessile suspension feeders. Rapid net deposition was also interrupted by more prolonged periods (tens to hundreds of years of low sedimentation that permitted colonization by epifaunal brachiopod-dominated communities. While most butter shale units are regionally extensive, the Oldenburg is

  19. Sedimentology of middle ordovician carbonates in the Argentine precordillera: evidence of regional relative sea-level changes

    Science.gov (United States)

    Keller, M.; Eberlein, S.; Lehnert, O.

    1993-07-01

    The Las Aguaditas Formation in the Argentine Precordillera of San Juan is the only Ordovician carbonate sequence deposited on a slope. Spiculites, mudstones and calcisiltites represent the autochthonous sediments, characterized by a fine lamination, rare fossils and their dark colour. The pelagic fauna consists of rare radiolarians/calcispheres, trinucleid trilobites, graptolites and conodonts. The latter are typical of an open marine environment and proved a Llanvirn—Llandeilo age for the Las Aguaditas Formation. In the upper part of the succession there are several intercalations of megabreccias. Their thickness decreases from about 20 to 4 m towards the top of the formation, accompanied by an increasing amount of carbonate turbidites. The clasts of the breccias are derived from the slope as well as the platform. Each of the megabreccia horizons represents a system of channels, lobes and interchannel deposits, which together form a slope apron. On top of the lower breccia a small biostrome developed, where bryozoans and crinoids are preserved in an autochthonous position. Sedimentation of the Las Aguaditas Formation started with the drowning of the underlying carbonate platform (San Juan limestones). Near the Arenig-Llanvirn boundary, a rapid ecstatic sea-level rise led to the deposition of graptolitic black shales and mudstones. Upwards, allochthonous carbonates become increasingly abundant. The onset of megabreccia deposition coincides with a major relative sea-level fall, caused by block movements in connection with rifting. The subsequent transition from breccia formation towards turbiditic sedimentation corresponds to an environmental shift from the slope towards the toe of slope and basin and marks a renewed moderate sea-level rise.

  20. Geologic drivers of late ordovician faunal change in laurentia: investigating links between tectonics, speciation, and biotic invasions.

    Directory of Open Access Journals (Sweden)

    David F Wright

    Full Text Available Geologic process, including tectonics and global climate change, profoundly impact the evolution of life because they have the propensity to facilitate episodes of biogeographic differentiation and influence patterns of speciation. We investigate causal links between a dramatic faunal turnover and two dominant geologic processes operating within Laurentia during the Late Ordovician: the Taconian Orogeny and GICE related global cooling. We utilize a novel approach for elucidating the relationship between biotic and geologic changes using a time-stratigraphic, species-level evolutionary framework for articulated brachiopods from North America. Phylogenetic biogeographic analyses indicate a fundamental shift in speciation mode-from a vicariance to dispersal dominated macroevolutionary regime-across the boundary between the Sandbian to Katian Stages. This boundary also corresponds to the onset of renewed intensification of tectonic activity and mountain building, the development of an upwelling zone that introduced cool, nutrient-rich waters into the epieric seas of eastern Laurentia, and the GICE isotopic excursion. The synchronicity of these dramatic geologic, oceanographic, and macroevolutionary changes supports the influence of geologic events on biological evolution. Together, the renewed tectonic activity and oceanographic changes facilitated fundamental changes in habitat structure in eastern North America that reduced opportunities for isolation and vicariance. They also facilitated regional biotic dispersal of taxa that led to the subsequent establishment of extrabasinal (=invasive species and may have led to a suppression of speciation within Laurentian faunas. Phylogenetic biogeographic analysis further indicates that the Richmondian Invasion was a multidirectional regional invasion event that involved taxa immigrating into the Cincinnati region from basins located near the continental margins and within the continental interior.

  1. Middle Ordovician subduction of continental crust in the Scandinavian Caledonides: an example from Tjeliken, Seve Nappe Complex, Sweden

    Science.gov (United States)

    Fassmer, Kathrin; Klonowska, Iwona; Walczak, Katarzyna; Andersson, Barbro; Froitzheim, Nikolaus; Majka, Jarosław; Fonseca, Raúl O. C.; Münker, Carsten; Janák, Marian; Whitehouse, Martin

    2017-12-01

    The Seve Nappe Complex of the Scandinavian Caledonides is thought to be derived from the distal passive margin of Baltica which collided with Laurentia in the Scandian Phase of the Caledonian Orogeny at 430-400 Ma. Parts of the Seve Nappe Complex were affected by pre-Scandian high- and ultrahigh-pressure metamorphism, in a tectonic framework that is still unclear, partly due to uncertainties about the exact timing. Previous age determinations yielded between 505 and 446 Ma, with a general trend of older ages in the North (Norrbotten) than in the South (Jämtland). New age determinations were performed on eclogite and garnet-phengite gneiss at Tjeliken in northern Jämtland. Thermodynamic modelling yielded peak metamorphic conditions of 25-27 kbar/680-760 °C for the garnet-phengite gneiss, similar to published peak metamorphic conditions of the eclogite (25-26 kbar/650-700 °C). Metamorphic rims of zircons from the garnet-phengite gneiss were dated using secondary ion mass spectrometry and yielded a concordia age of 458.9 ± 2.5 Ma. Lu-Hf garnet-whole rock dating yielded 458 ± 1.0 Ma for the eclogite. Garnet in the eclogite shows prograde major-element zoning and concentration of Lu in the cores, indicating that this age is related to garnet growth during pressure increase, i.e. subduction. The identical ages from both rock types, coinciding with published Sm-Nd ages from the eclogite, confirm subduction of the Seve Nappe Complex in Northern Jämtland during the Middle Ordovician in a fast subduction-exhumation cycle.

  2. Petrography and geochemistry of the volcanic rocks of the Rodeio Velho Member, Ordovician of the Camaqua basin (RS-Brazil): preliminary results

    International Nuclear Information System (INIS)

    Almeida, Delia del Pilar M. de; Lopes, Ricardo da C.; Gomes, Cristiane H.; Lima, Larissa de.

    2000-01-01

    A geochemical study based in REE, minor elements and petrographic analyses from the volcanic rocks pertaining to the Rodeio Velho Member, comprising lava flows and epizonal intrusive bodies, both corresponding to andesites, subalkaline and alkaline basalts and trachyandesites; and stratified pyroclastic deposits, showed that fractional crystallization of deep source magma is the fundamental mechanism controlling the relationships among these rocks. This igneous event occurred in an alkaline intraplate environment, associated to a widespread extension tectonics, probably corresponding to a final stage of the Pan African - Brasiliano Orogeny during the Middle Ordovician. (author)

  3. TrishearCreator: A tool for the kinematic simulation and strain analysis of trishear fault-propagation folding with growth strata

    Science.gov (United States)

    Liu, Chun; Yin, Hongwei; Zhu, Lili

    2012-12-01

    TrishearCreator is a platform independent web program constructed in Flash, which enables fold modeling, numerical simulation of trishear fault-propagation folding and strain analysis, etc. In the program, various types of original strata, such as folds and inclined strata can be easily constructed via adjusting shape parameters. In the simulation of trishear fault-propagation folding, growth strata and strain ellipses are calculated and displayed simultaneously. This web-based program is easy to use. Model parameters are changed by simple mouse actions, which have the advantage of speed and simplicity. And it gives an instant visual appreciation of the effect of changing the parameters that are used to construct the initial configuration of the model and the fold-propagation folding. These data can be exported to a text file, and be shared with other geologists to replay the kinematic evolution of structures using the program.

  4. Fractal analysis on the crack evolution and fluid flow in the overburden strata caused by high steep thick coal seam mining

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jin-an; Feng Jin-yan; Cai Mei-feng [University of Science and Technology Beijing, Beijing (China). School of Civil and Environmental Engineering

    2008-02-15

    By employing fractal theory, the evolution of the cracks in overburden strata caused by high steep coal seam mining was analyzed. It was shown that the fracture angle in the border of the collapsed zones is steeper than that near the surface. The ratio of the fractal dimensions of closed cracks to open cracks gradually increases with the exploration depth. The closure of the cracks plays an active role in preventing rain flowing into the mining face. The study manifests the relationship between the flux in the working face and the ratio of crack closure in the overburden strata, which shows a parabolic form. It verifies further the active role of crack closure in the prevention of fluid flow in the strata. 7 refs., 5 figs., 2 tabs.

  5. 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.

  6. A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids

    Science.gov (United States)

    Lamsdell, James C.; Briggs, Derek E. G.; Liu, Huaibao P.; Witzke, Brian J.; McKay, Robert M.

    2015-10-01

    Euchelicerates were a major component of Palaeozoic faunas, but their basal relationships are uncertain: it has been suggested that Xiphosura—xiphosurids (horseshoe crabs) and similar Palaeozoic forms, the synziphosurines—may not represent a natural group. Basal euchelicerates are rare in the fossil record, however, particularly during the initial Ordovician radiation of the group. Here, we describe Winneshiekia youngae gen. et sp. nov., a euchelicerate from the Middle Ordovician (Darriwilian) Winneshiek Lagerstätte of Iowa, USA. Winneshiekia shares features with both xiphosurans (a large, semicircular carapace and ophthalmic ridges) and dekatriatan euchelicerates such as chasmataspidids and eurypterids (an opisthosoma of 13 tergites). Phylogenetic analysis resolves Winneshiekia at the base of Dekatriata, as sister taxon to a clade comprising chasmataspidids, eurypterids, arachnids, and Houia. Winneshiekia provides further support for the polyphyly of synziphosurines, traditionally considered the stem lineage to xiphosurid horseshoe crabs, and by extension the paraphyly of Xiphosura. The new taxon reveals the ground pattern of Dekatriata and provides evidence of character polarity in chasmataspidids and eurypterids. The Winneshiek Lagerstätte thus represents an important palaeontological window into early chelicerate evolution.

  7. The Effect of Water Chemistry on Thermochemical Sulfate Reduction: A Case Study from the Ordovician in the Tazhong Area, Northwest China

    Directory of Open Access Journals (Sweden)

    Hongxia Li

    2017-01-01

    Full Text Available Formation water chemistry, sulfate sulfur isotopes, and associated H2S contents and sulfur isotopes were measured from the Ordovician in Tazhong area, Tarim Basin. The aim is to elucidate the effects of geochemical composition of formation water on thermochemical sulfate reduction (TSR and potential usage of SO4/Cl ratios as a new proxy for TSR extents in areas, where H2S and thiaadamantanes (TAs data are not available. The formation water has SO4/Cl ratios from 0.0002 to 0.016, significantly lower than 0.04 to 0.05 from 3 to 7 times evapoconcentrated seawater. Thus, the low values are explained to result from TSR. Furthermore, the SO4/Cl ratios show negative correlation relationships to TAs and H2S concentrations, indicating that TSR occurred in a relatively closed system and SO4/Cl ratio can be used to indicate TSR extents in this area. Extensive TSR in the Cambrian in the Tazhong area, represented by low SO4/Cl ratios and high H2S and TAs concentrations, is accompanied by formation water with high TDS and Mg concentrations, indicating the effects of water chemistry on TSR under a realistic geological background. In contrast, the low TSR extent in the Ordovician may have resulted from limited TSR reaction duration and total contribution of aqueous SO42-.

  8. Middle Ordovician subduction of continental crust in the Scandinavian Caledonides - an example from Tjeliken, Seve Nappe Complex, Sweden

    Science.gov (United States)

    Fassmer, Kathrin; Andersson, Barbro; Klonowska, Iwona; Walczak, Katarzyna; Froitzheim, Nikolaus; Majka, Jarosław; Fonseca, Raul

    2017-04-01

    The Seve Nappe Complex (SNC) in the Scandinavian Caledonides represents the distal part of the margin of Baltica, which was subducted to depth of UHP metamorphism during the Caledonian orogeny. In contrast to the ages determined for the Western Gneiss Complex in Western Norway (ca. 420 - 400 Ma) which is interpreted to represent the subducted Baltican basement , the ages in the SNC and related nappes are overall older (ca. 500-430 Ma), with a general trend of higher ages in the North (Norrbotten) than in the South (Jämtland). As the previously published ages in the SNC are quite diverging it is difficult to reconstruct the tectonometamorphic history of this unit. Therefore exact dating with different methods is necessary to get a better constraint on the exact timing of subduction. We present new age determinations on an eclogite and a garnet-phengite schist from Tjeliken in northern Jämtland, Sweden. There the SNC can be divided into three tectonic units, an Eastern, Middle and Western belt. The locality of Mt. Tjeliken is situated in the Eastern Belt. Thermodynamic modelling of the eclogite yielded a pressure of 25-26 kbar at 650-700 °C (Majka et al. 2014). Previous dating produced diverging ages of 460±4 Ma (Sm-Nd mineral isochrones, Brueckner & Van Roermund 2007) and 446±1 Ma (U-Pb zircon dating, Root & Corfu 2012). In this study metamorphic rims of zircons from the garnet-phengite schist were dated using secondary ion mass spectrometry (SIMS) and yielded a concordia age of 458.9 ± 2.5 Ma. Lu-Hf garnet-whole rock dating yielded 458.5 ± 1.1 Ma for the eclogite. Garnet in the eclogite shows a prograde major-element zoning and a concentration of Lu in the cores, indicating that this age is related to garnet growth during pressure increase, i.e. subduction. The identical ages from both rock types confirm subduction of the outer margin of Baltica during the Middle Ordovician in a fast subduction-exhumation cycle. The fact that Sm-Nd and Lu-Hf dating yielded

  9. Magneto stratigraphy and 40Ar - 39Ar dating of the neogene synorogenic strata of Northern Mendoza, Argentina: Tectonic implications

    International Nuclear Information System (INIS)

    Irigoyen, Maria V.; Ramos, Victor A.; Brown, Richard L.

    1998-01-01

    Full text: At the southernmost extension of the Pre cordillera fold-and-thrust belt, 33 S latitude, about 4000 m of Cenozoic foreland-basin strata record the eastern migration of the Andean thrust from since the Neogene. These deposits accumulated in response to exhumation and deformation of the western Principal and Frontal cordilleras. The detrial clastic strata cropping out in the La Pilona-Tupungato region, comprise five formation units that record fluvial, eolian and alluvial deposition in an arid setting. To link the sequence of deformational events in the western mountain belts with the sedimentary record, all units except the youngest have been dated using magnetic polarity stratigraphy calibrated with 40 Ar - 39 Ar dates on inter bedded tephras. A precise chronology of these deposits in conjunction with a multiple data set that include rates of sedimentation in the foreland, a provenance study on these rocks, and facies and textural patterns, provide the basis for documenting details of tectonic activity, volcanism and deposition. The oldest Marinio Fm., whose deposition spans ∼15.7-12.2 Ma, is interpreted to record two phases of thrusting in the Principal Cordillera (Irigoyen 1997). The earlier phase is tied to deformation of the Mesozoic andesitic volcanic complex cropping out in the western part of the Aconcagua fold-and-thrust belt. The second phase of thrusting is linked with deformation of the Mesozoic marine sequences of the central part of the Aconcagua fold-and-thrust belt. The overlying La Pilona Fm., whose deposition spans ∼11.7-9.0 Ma, is thought to record the initiation of exhumation of the Frontal Cordillera. Provenance and paleocurrent data are consistent with clast derivation from northwestern highland sources (i.e., cordon and cuchillas del Tigre) which provided volcanic detritus from the Choiyoi Group and low-grade metamorphic and sedimentary rocks of lower Paleozoic age. Exhumation and displacement of the Frontal Cordillera

  10. Raster Images of Geologic Maps of Middle Proterozoic Belt strata in parts of Benewah, Bonner, Kootenai and Shoshone Counties, Idaho and Lincoln, Mineral and Sanders Counties, Montana

    Science.gov (United States)

    Boleneus, David E.; Appelgate, Larry M.; Joseph, Nancy L.; Brandt, Theodore R.

    2001-01-01

    Geologic maps of the western part of the Belt Basin of western Montana and northern Idaho were converted into digital raster (TIFF image) format to facilitate their manipulation in geographic information systems. The 85-mile x 100-mile map area mostly contains rocks belonging to the lower and middle Belt Supergroup. The area is of interest as these Middle Proterozoic strata contain vein-type lead-zinc-silver deposits in the Coeur d?Alene Mining District in the St. Regis and Revett formations and strata-bound copper-silver deposits, such as the Troy mine, within the Revett Formation. The Prichard Formation is also prospective for strata-bound lead-zinc deposits because equivalent Belt strata in southern British Columbia, Canada host the Sullivan lead-zinc deposit. Map data converted to digital images include 13 geological maps at scales ranging from 1:48,000 to 1:12,000. Geologic map images produced from these maps by color scanning were registered to grid tick coverages in a Universal Transverse Mercator (North American Datum of 1927, zone 11) projection using ArcView Image Analysis. Geo-registering errors vary from 10 ft to 114 ft.

  11. Paleomagnetism and Magnetostratigraphy of Upper Permian to Lower Triassic (?) Beaufort Group Strata at Bethulie, Karoo Basin, Free State Province, South Africa

    Science.gov (United States)

    Geissman, J. W.; Gastaldo, R. A.; Neveling, J.; Makubalo, S.

    2017-12-01

    A multifaceted approach to understand the timing of interpreted environmental changes during the Late Permian to possibly Early Triassic (?) time in the Beaufort Group strata of the Karoo Basin includes work to establish robust magnetic polarity records for sections previously interpreted to encompass end-Permian extinction events. Demonstrating the preservation of an early-acquired remanence (RM) in Karoo strata is required for a robust magnetostratigraphy. Yet, this is challenging due to thermochemical effects related to the Early Jurassic (ca. 183 Ma) Karoo Large Igneous Province (LIP), and the NE to SW increase in burial diagenesis attending Cape Fold Belt tectonism. Documentation of a primary RM in these strata, which appears to be preserved in some areas, requires careful laboratory- and field-based assessment. We report data from 53 sites collected at the well-studied Bethulie section, Free State Province, in which several 50 mA/m). Collectively, we interpret these data to indicate that any ChRM, with the exception of those from host strata in baked contacts, that persists above Tlub of 425oC is pre-Karoo LIP in origin, and likely primary at the Bethulie locality.

  12. Lake-level Fluctuation and Climate Cyclicity Observed in Lake Strata in the Northwestern Qaidam Basin, China

    Science.gov (United States)

    Riegel, H. B.; Heermance, R. V., III; Nie, J.; Su, Q.; Garzione, C. N.

    2015-12-01

    The Pliocene and Quaternary are times of rapid, extreme climate variability, but 3-D geologic exposures of lacustrine strata from this time are rare, impeding observations of the impact of climate-change on lake sedimentation. The Qaidam Basin (QB) in western China provides a unique geologic setting, where internally drained lakes have existed for the past few million years, and recent deformation of the basin floor has uplifted and exposed lacustrine strata. This stratigraphy records a detailed history of lake level fluctuation, evaporite deposition, and climate change. We provide new paleomagnetic, δ18O and δ13C data combined with detailed sedimentology from the lower 475 m of a 900 m thick stratigraphic section (38.28N, 91.54E) in the northwestern QB to reveal a high-resolution record of sedimentation and climate change during the Plio-Quaternary. 12 magnetozones indicate an age for the lower half of the section between 6.0-3.0 Ma. The section consists of 9 lithofacies (1 mudstone, 4 sandstone, 1 conglomerate, 2 gypsum, 1 halite) that can be divided into 3 stratigraphic units based on evaporite concentration. Alternating mud, gypsum, and halite beds imply multiple lake-level fluctuations and occasional complete drying of the lake. This is consistent with >12.5‰ variation in the δ18O values of lacustrine carbonates (δ18Oc), indicating large-scale lake level fluctuation below 410 m, consistent with the boundary of Unit 1 and 2. Between 410 and 475 m, the δ18Oc values are ~-5 ‰. Above 475 m, an increase in gypsum concentration causes a thick salt-crust to develop on the outcrop, making sampling impossible. This stratigraphic level corresponds to an age of ~3.0 Ma, when the QB became hyper-arid. The presence of gypsum and halite throughout the section implies that the QB was arid and internally drained by at least 6 Ma, although the basin may have been divided into multiple lakes based on the bimodal δ18O values from different parts of the QB during that

  13. Paleomagnetic and palynologic analyses of Albian to Santonian strata at Bayn Shireh, Burkhant, and Khuren Dukh, eastern Gobi Desert, Mongolia

    Science.gov (United States)

    Hicks, J.F.; Brinkman, D.L.; Nichols, D.J.; Watabe, M.

    1999-01-01

    strata are no older than middle to late Albian. The rocks at Bayn Shireh (the Bayn Shireh Formation) have been assigned a 'Baynshirenian' biostratigraphic age that may range from Cenomanian to early Campanian. The magnetostratigraphy results presented here indicate that the strata at both the Bayn Shireh and Burkhant localities do not cross the Santonian/Campanian Stage boundary, however, as this is believed to lie at, or very near, the C34n/C33r reversal boundary. Thus, the Bayn Shireh Formation was most likely deposited near the end of the Cretaceous Long Normal Interval, no later than the latest Santonian.

  14. What matters most: protocol for a randomized controlled trial of breast cancer surgery encounter decision aids across socioeconomic strata.

    Science.gov (United States)

    Durand, Marie-Anne; Yen, Renata West; O'Malley, A James; Politi, Mary C; Dhage, Shubhada; Rosenkranz, Kari; Weichman, Katie; Margenthaler, Julie; Tosteson, Anna N A; Crayton, Eloise; Jackson, Sherrill; Bradley, Ann; Volk, Robert J; Sepucha, Karen; Ozanne, Elissa; Percac-Lima, Sanja; Song, Julia; Acosta, Jocelyn; Mir, Nageen; Elwyn, Glyn

    2018-02-13

    Breast cancer is the most commonly diagnosed malignancy in women. Mastectomy and breast-conserving surgery (BCS) have equivalent survival for early stage breast cancer. However, each surgery has different benefits and harms that women may value differently. Women of lower socioeconomic status (SES) diagnosed with early stage breast cancer are more likely to experience poorer doctor-patient communication, lower satisfaction with surgery and decision-making, and higher decision regret compared to women of higher SES. They often play a more passive role in decision-making and are less likely to undergo BCS. Our aim is to understand how best to support women of lower SES in making decisions about early stage breast cancer treatments and to reduce disparities in decision quality across socioeconomic strata. We will conduct a three-arm, multi-site randomized controlled superiority trial with stratification by SES and clinician-level randomization. At four large cancer centers in the United States, 1100 patients (half higher SES and half lower SES) will be randomized to: (1) Option Grid, (2) Picture Option Grid, or (3) usual care. Interviews, field-notes, and observations will be used to explore strategies that promote the interventions' sustained use and dissemination. Community-Based Participatory Research will be used throughout. We will include women aged at least 18 years of age with a confirmed diagnosis of early stage breast cancer (I to IIIA) from both higher and lower SES, provided they speak English, Spanish, or Mandarin Chinese. Our primary outcome measure is the 16-item validated Decision Quality Instrument. We will use a regression framework, mediation analyses, and multiple informants analysis. Heterogeneity of treatment effects analyses for SES, age, ethnicity, race, literacy, language, and study site will be performed. Currently, women of lower SES are more likely to make treatment decisions based on incomplete or uninformed preferences, potentially

  15. Tracing the Cambro-Ordovician ferrosilicic to calc-alkaline magmatic association in Iberia by in situ U-Pb SHRIMP zircon geochronology (Gredos massif, Spanish Central System batholith)

    Science.gov (United States)

    Díaz-Alvarado, Juan; Fernández, Carlos; Chichorro, Martim; Castro, Antonio; Pereira, Manuel Francisco

    2016-06-01

    U-Pb geochronological study of zircons from nodular granites and Qtz-diorites comprising part of Variscan high-grade metamorphic complexes in Gredos massif (Spanish Central System batholith) points out the significant presence of Cambro-Ordovician protoliths among the Variscan migmatitic rocks that host the Late Carboniferous intrusive granitoids. Indeed, the studied zone was affected by two contrasted tectono-magmatic episodes, Carboniferous (Variscan) and Cambro-Ordovician. Three main characteristics denote a close relation between the Cambro-Ordovician protholiths of the Prado de las Pozas high-grade metamorphic complex, strongly reworked during the Variscan Orogeny, and other Cambro-Ordovician igneous domains in the Central Iberian Zone of the Iberian Massif: (1) geochemical features show the ferrosilicic signature of nodular granites. They plot very close to the average analysis of the metavolcanic rocks of the Ollo de Sapo formation (Iberia). Qtz-diorites present typical calc-alkaline signatures and are geochemically similar to intermediate cordilleran granitoids. (2) Both Qtz-diorite and nodular granite samples yield a significant population of Cambro-Ordovician ages, ranging between 483 and 473 Ma and between 487 and 457 Ma, respectively. Besides, (3) the abundance of zircon inheritance observed on nodular granites matches the significant component of inheritance reported on Cambro-Ordovician metagranites and metavolcanic rocks of central and NW Iberia. The spatial and temporal coincidence of both peraluminous and intermediate granitoids, and specifically in nodular granites and Qtz-diorite enclaves of the Prado de las Pozas high-grade complex, is conducive to a common petrogenetic context for the formation of both magmatic types. Tectonic and geochemical characteristics describe the activity of a Cambro-Ordovician arc-back-arc tectonic setting associated with the subduction of the Iapetus-Tornquist Ocean and the birth of the Rheic Ocean. The extensional

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

    Science.gov (United States)

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

    2017-11-01

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

  17. Progress on the palynostratigraphy of the Permian strata in Rio Grande do Sul State, Paraná Basin, Brazil

    Directory of Open Access Journals (Sweden)

    Souza Paulo A.

    2005-01-01

    Full Text Available A review of published papers and results of analysis of new material have allowed improvements on the palynostratigraphy of the Permian strata of the Paraná Basin in Rio Grande do Sul State. Based on first and last occurrences of certain species of pollen taxa, two palynozones are formalized, these are the Vittatina costabilis and Lueckisporites virkkiae Interval Zones, in ascending order. The Vittatina costabilis Interval Zone is subdivided into two units, in ascending order the Protohaploxypinus goraiensis and the Hamiapollenites karrooensis Subzones, and is recognized from the glacial (Itararé Group and post-glacial sequence (Rio Bonito Formation and the base of the Palermo Formation. The Lueckisporites virkkiae Interval Zone occurs from the uppermost Rio Bonito Formation, through the Palermo and Irati formations, and into the Serra Alta and Teresina formations. The main characteristics and reference sections are established, as well as additional criteria to recognize biostratigraphical units, in accordance with the International Stratigraphic Guide. Palynostratigraphical correlation suggests that the Vittatina costabilis Zone concerns the Early Permian (early Cisuralian, while the Lueckisporites virkkiae is regarded as late Early Permian to early Middle Permian (late Cisularian to early Guadalupian.

  18. 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.

  19. 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 <0.1 percent of the bulk jasper. Most jasper beds are enriched in U, V, P, and Mo relative to the North American Shale Composite, reflecting a predominantly seawater source, whereas REE distribution patterns (positive Eu and negative Ce anomalies) reflect variable mixing of hydrothermal solutions with oxic seawater at dilution ratios of ???102 to 104. Trace element variations in the gel precursor to the jasper are thought to have been controlled by coprecipitation and/or adsorption by Fe oxyhydroxide particles that formed by the oxidation of hydrothermal Fe2+ within the variably seawater-diluted hydrothermal plume(s). Thick jasper layers near the H??ydal VMS orebody show distinct positive As/Fe and Sb/Fe anomalies that are attributed to near-vent rapid settling of Si-Fe particles derived from As- and Sb

  20. Simulation of regional ground-water flow in the Cambrian-Ordovician aquifer system in the northern Midwest, United States: in Regional aquifer-system analysis

    Science.gov (United States)

    Mandle, R.J.; Kontis, A.L.

    1992-01-01

    A six-State area in the northern Midwest of the United States has become increasingly dependent on ground water from the Cambrian-Ordovician aquifer system, which consists of a sequence of sandstones, carbonate rocks, and shales. Ground-water withdrawals from the aquifer system began in the late 1800's and increased to approximately 684 million gallons per day (1,058 cubic feet per second) by 1980. This withdrawal has caused more than 900 feet of decline in the potentiometric surface of the aquifer system in parts of the Chicago, Ill., area. Pumping in Minneapolis-St. Paul, Minn., Milwaukee, Wis., and central Iowa has produced a few hundreds of feet of water-level decline.

  1. Carbonate microfacies of the San Juan Formation (Ordovician: Oepikodus evae and Oepikodus intermedius conodont zones), Niquivil, Central Precordillera, Province of San Juan (Argentina)

    International Nuclear Information System (INIS)

    Soria, T.; Beresi, M.; Mestre, A.; Heredia, S.; Rodríguez, M.C.

    2017-01-01

    This contribution presents the description and interpretation of carbonate microfacies of the San Juan Formation (Ordovician) at the Niquivil section, considering the stratigraphical interval between the Oepikodus evae and Oepikodus intermedius conodont zones. The distribution of the microfacies and the conodonts assemblages allow us to identify different sub-environments within the late Floian carbonate ramp of the Central Precordillera. Five microfacies were recognized from the base to the top: M1 Bioclastic mudstone-wackestone; M2 Bioclastic-peloidal wackestone; M3 Intra-bioclastic wackestone; M4 Intra-bioclastic packstone; M5 Peloidal grainstone. The vertical distribution of these microfacies indicates a shallowing trend of the carbonate ramp in the Niquivil section for this temporal interval, which suggests a middle ramp environment with low energy, without wave action, and that evolved towards the middle-inner ramp environment with more energy by wave action and development of tempestites. [es

  2. 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.

  3. Sequence stratigraphy in the middle Ordovician shale successions, mid-east Korea: Stratigraphic variations and preservation potential of organic matter within a sequence stratigraphic framework

    Science.gov (United States)

    Byun, Uk Hwan; Lee, Hyun Suk; Kwon, Yi Kyun

    2018-02-01

    The Jigunsan Formation is the middle Ordovician shale-dominated transgressive succession in the Taebaeksan Basin, located in the eastern margin of the North China platform. The total organic carbon (TOC) content and some geochemical properties of the succession exhibit a stratigraphically distinct distribution pattern. The pattern was closely associated with the redox conditions related to decomposition, bulk sedimentation rate (dilution), and productivity. To explain the distinct distribution pattern, this study attempted to construct a high-resolution sequence stratigraphic framework for the Jigunsan Formation. The shale-dominated Jigunsan Formation comprises a lower layer of dark gray shale, deposited during transgression, and an upper layer of greenish gray siltstone, deposited during highstand and falling stage systems tracts. The concept of a back-stepped carbonate platform is adopted to distinguish early and late transgressive systems tracts (early and late TST) in this study, whereas the highstand systems tracts and falling stage systems tracts can be divided by changes in stacking patterns from aggradation to progradation. The late TST would be initiated on a rapidly back-stepping surface of sediments and, just above the surface, exhibits a high peak in TOC content, followed by a gradually upward decrease. This trend of TOC distribution in the late TST continues to the maximum flooding surface (MFS). The perplexing TOC distribution pattern within the late TST most likely resulted from both a gradual reduction in productivity during the late TST and a gradual increase in dilution effect near the MFS interval. The reduced production of organic matter primarily incurred decreasing TOC content toward the MFS when the productivity was mainly governed by benthic biota because planktonic organisms were not widespread in the Ordovician. Results of this study will help improve the understanding of the source rock distribution in mixed carbonate

  4. Metals in Devonian kerogenous marine strata at Gibellini and Bisoni properties in southern Fish Creek Range, Eureka County, Nevada

    Science.gov (United States)

    Desborough, George A.; Poole, F.G.; Hose, R.K.; Radtke, A.S.

    1979-01-01

    A kerogen-rich sequence of siliceous mudstone, siltstone, and chert as much as 60 m thick on ridge 7129 in the southern Fish Creek Range, referred to as Gibellini facies of the Woodruff Formation, has been evaluated on the surface and in drill holes principally for its potential resources of vanadium, zinc, selenium, molybdenum, and syncrude oil content. The strata are part of a strongly deformed allochthonous mass of eugeosynclinal Devonian marine rocks that overlie deformed allochthonous Mississippian siliceous rocks and relatively undeformed autochthonous Mississippian Antler flysch at this locality. The vanadium in fresh black rocks obtained from drill holes and fresh exposures in trenches and roadcuts occurs chiefly in organic matter. Concentrations of vanadium oxide (V2O5) in unoxidized samples range from 3,000 to 7,000 ppm. In oxidized and bleached rock that is prevalent at the surface, concentrations of vanadium oxide range from 6,000 to 8,000 ppm, suggesting a tendency toward enrichment due to surficial weathering and ground-water movement. Zinc occurs in sphalerite, and selenium occurs in organic matter; molybdenum appears to occur both in molybdenite and in organic matter. Concentrations of zinc in unoxidized rock range from 4,000 to 18,000 ppm, whereas in oxidized rock they range from 30 to 100 ppm, showing strong depletion due to weathering. Concentrations of selenium in unoxidized rock range from 30 to 200 ppm, whereas in oxidized rock they range from 200 to 400 ppm, indicating some enrichment upon weathering. Concentrations of molybdenum in unoxidized rock range from 70 to 960 ppm, whereas in oxidized rock they range from 30 to 80 ppm, indicating strong depletion upon weathering. Most fresh black rock is low-grade oil shale, and yields as much as 12 gallons/short ton of syncrude oil. Metahewettite is the principal vanadium mineral in the oxidized zone, but it also occurs sparsely as small nodules and fillings of microfractures in unweathered strata

  5. Task 50 - deposition of lignites in the Fort Union Group and related strata of the northern Great Plains

    Energy Technology Data Exchange (ETDEWEB)

    Hartman, J.H.; Roth, B.; Kihm, A.J.

    1997-08-11

    Late Cretaceous, Paleocene, and early Eocene geologic and paleontologic studies were undertaken in western North Dakota, eastern and south-central Montana, and northwestern and northeastern Wyoming. These study areas comprise the Williston, Bighorn, and Powder River Basins, all of which contain significant lignite resources. Research was undertaken in these basins because they have the best geologic sections and fossil record for the development of a chronostratigraphic (time-rock) framework for the correlation of lignite beds and other economic resources. A thorough understanding of the precise geologic age of the deposition of sediments permits a powerful means of interpreting the record of geologic events across the northern Great Plains. Such an understanding allows for rigorous interpretation of paleoenviromnents and estimates of resource potential and quality in this area of economically significant deposits. This work is part of ongoing research to document change in the composition of molluscan fossil faunas to provide a paleoenvironmentally sensitive independent means of interpreting time intervals of brief duration during the Late Cretaceous, Paleocene, and Eocene. This study focuses on the record of mollusks and, to a lesser extent, mammals in the (1) Hell Creek-Tullock Formations, which include the Cretaceous-Paleocene boundary, in the western portion of the Williston Basin, Montana; (2) uppermost Cretaceous, Paleocene, and lowermost Eocene strata in western North Dakota, which -includes the last interior seaway in North Dakota; (3) upper Paleocene and lowermost Eocene of the northern portion of the Bighorn Basin of south-central Montana and northwestern Wyoming; and (4) Powder River Basin of northeastern Wyoming and southeastern Montana. The geologic record provides different physical and paleontological information to aid in interpreting the geologic record through the study interval.

  6. Facies analysis of an ancient, dismembered, large caldera complex and implications for intra-arc subsidence: Middle Jurassic strata of Cobre Ridge, southern Arizona, USA

    Science.gov (United States)

    Riggs, Nancy R.; Busby-Spera, Cathy J.

    1991-11-01

    The Middle Jurassic (˜ 170 Ma) Cobre Ridge caldera is an elongate caldera complex that formed during the eruption of the tuff of Pajarito, a crystal-rich rhyodacite ignimbrite with an estimated volume > 1000 km 3. The caldera subsided in two subequal blocks: to the southeast, caldera-forming ignimbrite is as much as 3000 m thick, whereas the northwest half of the caldera subsided to lesser depths during the initial eruption, but was the locus of subsidence during subsequent eruptions, providing a depocenter for a > 1.5 km-thick section of secondary- and post-collapse volcanic and sedimentary strata. These strata record moat formation and filling and waning volcanism, including: (1) areally restricted ignimbrites up to several tens of meters thick that may have been ponded between caldera margins and/or fault scarps; (2) a ⩾ 600 m-thick ignimbrite whose eruption probably caused further collapse of the caldera or enlargement of the caldera margins; (3) a localized debris apron deposit up to 500 m thick that represents material reworked from intra-caldera pyroclastic deposits and possibly caldera walls; and (4) eolian and fluvial sandstones and water-lain tuffs. Megabreccia blocks as large as 0.5 km along strike probably demarcate approximate caldera margins, suggesting that the composite caldera was approximately 50 km long by 25 km wide. The preserved thickness of the strata of Cobre Ridge ( > 4500 m) is greater than many ancient continental volcanic sequences, suggesting external (i.e. tectonic) controls on subsidence, but preservation of this great thickness of strata is apparently due entirely to volcanic subsidence.

  7. On-Site Radon Detection of Mining-induced Fractures from Overlying Strata to the Surface: A Case Study of the Baoshan Coal Mine in China

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    Wei Zhang

    2014-12-01

    Full Text Available Large-scale longwall mining of shallow coal seams may cause mining-induced fractures that can project completely through to the surface. This could lead to a series of mine safety and environmental issues, further deteriorating the already fragile ecological environment in the Western mining areas in China. Therefore, an accurate and effective understanding of the spatiotemporal evolution law of mining-induced fractures in overlying strata and its relationship to upper aquifers is critical. In this paper, the application of the geophysical-chemical properties of radon in mining engineering is explored as a potential solution to the shortcomings of existing surveying methods. A radioactive measurement method is proposed for the detection of the development of mining-induced fractures from overlying strata to the surface in the Baoshan Coal Mine (BCM. The on-site test indicated that the first weighting step is approximately 60 m, the average periodic weighting step is approximately 20 m, and the influence coverage of the advanced abutment pressure is approximately 30 m. The presented method could be used as an indirect technical support to increase the safety of coal mining by acting as a simple, fast, and reliable method of detecting mining-induced fractures in overlying strata.

  8. Preliminary study of uranium in Pennsylvanian and lower Permian strata in the Powder River Basin, Wyoming and Montana, and the Northern Great Plains

    International Nuclear Information System (INIS)

    Dunagan, J.F. Jr.; Kadish, K.A.

    1977-11-01

    Persistent and widespread radiometric anomalies occur in Pennsylvanian and Lower Permian strata in the subsurface of the northern Great Plains and the Powder River Basin. The primary host lithology of these anomalies is shale interbedded with sandstone, dolomite, and dolomitic sandstone. Samples from the project area indicate that uranium is responsible for some anomalies. In some samples there seems to be a correlation between high uranium content and high organic-carbon content, which possibly indicates that carbonaceous material acted as a trapping mechanism in some strata. The Pennsylvanian and Permian rocks studied are predominantly marine carbonates and clastics, but there are rocks of fluvial origin in the basal Pennsylvanian of Montana, North Dakota, and South Dakota and in the Pennsylvanian and Permian deposits on the east flank of the Laramie Mountains. Fine-grained clastic rocks that flank the Chadron arch in western Nebraska are possibly of continental origin. The trend of the Chadron arch approximately parallels the trend of radiometric anomalies in the subsurface Permian-Pennsylvanian section. Possible source areas for uranium in the sediments studied were pre-Pennsylvanian strata of the Canadian Shield and Precambrian igneous rocks of the Ancestral Rocky Mountains

  9. Main factors for large accumulations of natural gas in the marine carbonate strata of the Eastern Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Quanyou Liu

    2017-04-01

    Full Text Available The natural gas accumulation zone, where the marine carbonate rock strata are developed, was formed in the eastern Sichuan Basin under the influence of several main tectonic movements (Caledonian Movement, Indosinian Movement, Yanshanian Movement, and Himalayan Movement. Most natural gas reservoirs exhibit the structural-stratigraphic traps together with multistage accumulation, late-stage adjustment and reformation, et cetera. The natural gas accumulation zone (or so-called gas reservoir groups is controlled by the following main factors: multi-sourced and multi-formed hydrocarbons for marine source rocks (i.e. Lower Silurian Longmaxi Formation, Lower Permian, Upper Permian Longtan Formation, paleo-uplift, paleoslope, and the hinge belt controlled by the steep dip structures, namely the Lower and Middle Triassic high-quality gypsum. Three sets of high-quality source rocks (i.e. S1l, P1, P2l account for the abundant hydrocarbon supply for natural gas accumulation in the eastern Sichuan area, especially in the destructed oil reservoir formed earlier. The said destructed oil reservoir not only provides the preservation space for natural gas reservoir that will take place later, but it also provides the hydrocarbon source for thermal cracking of hydrocarbons and thermochemical sulfate reduction (TSR. Although the gas reservoirs in the eastern part of the Sichuan Basin experienced multi-stage adjustment and reformation at later times, the thick and high-quality gypsum as well as the mudstone, as available caprocks, have offered a good preservation condition for the underlying gas reservoirs. The paleohighs (e.g. Luzhou paleohigh and Kaijiang paleohigh, the Permian platform margin slope, and the structurally transformed slope under the function of the steep dip anticline in the eastern Sichuan not only form the high-quality carbonate reservoir, but they also became favorable for oil and gas accumulation. The difference in hydrocarbon generation

  10. Eustatic and tectonic control of deposition of the lower and middle Pennsylvanian strata of the Central Appalachian Basin

    Science.gov (United States)

    Chesnut, D.R.

    1997-01-01

    Stratigraphic analysis of Lower and Middle Pennsylvanian rocks of part of the Central Appalachian Basin reveals two orders of cycles and one overall trend in the vertical sequence of coal-bearing rocks. The smallest order cycle, the coal-clastic cycle, begins at the top of a major-resource coal bed and is composed of a vertical sequence of shale, siltstone, sandstone, seat rock, and overlying coal, which, in turn, is overlain by the next coal-clastic sequence. The average duration of the coal-clastic cycle has been calculated to be about 0.4 m.y. The major marine-transgression cycle is composed of five to seven coal-clastic cycles and is distinguished by the occurrence of widespread, relatively thick (generally thicker than 5 m) marine strata at its base. The duration of this cycle has been calculated to be about 2.5 m.y. The Breathitt coarsening-upward trend describes the general upward coarsening of the Middle Pennsylvanian part of the Breathitt Group. The Breathitt Group includes eight major marine-transgression cycles, and was deposited during a period of approximately 20 m.y. The average duration of coal-clastic cycles is of the same order of magnitude (105 year) as the Milankovitch orbital-eccentricity cycles, and matches the 0.4 m.y. second-order eccentricity cycle (Long Earth-Eccentricity cycle). These orbital periodicities are thought to modulate glacial stages and glacio-eustatic levels. The calculated periodicities of the coal-clastic cycles can be used as evidence for glacio-eustatic control of the coal-bearing rocks of the Appalachian Basin. The 2.5-m.y. periodicity of the major marine-transgression cycle does not match any known orbital or tectonic cycle; the cause of this cycle is unknown, but it might represent episodic thrusting in the orogen, propagation of intraplate stresses, or an unidentified orbital cycle. The Breathitt coarsening-upward trend is interpreted to represent the increasing intensity and proximity of the Alleghenian Orogeny

  11. Distribution of throughfall and stemflow in multi-strata agroforestry, perennial monoculture, fallow and primary forest in central Amazonia, Brazil

    Science.gov (United States)

    Schroth, Götz; Ferreira da Silva, Luciana; Wolf, Marc-Andree; Geraldes Teixeira, Wenceslau; Zech, Wolfgang

    1999-07-01

    The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi-strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open-area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for

  12. A condição feminina em Lisístrata e em A Fonte das Mulheres

    Directory of Open Access Journals (Sweden)

    Amanda Jéssica Ferreira Moura

    2016-12-01

    Full Text Available O presente trabalho dá enfoque à comédia grega Lisístrata (411 a.C, de Aristófanes, e a sua adaptação cinematográfica, o filme A Fonte das Mulheres (La Source des Femmes, 2011, coproduzido por França, Bélgica e Itália e dirigido pelo romeno Radu Mihaileanu. Ambas as obras trazem a questão da greve do sexo instaurada pelas mulheres, mas os motivos e os desdobramentos dessa greve são divergentes. Para desenvolvimento de nossa pesquisa, partimos da descrição de excertos da comédia e de cenas do filme, considerando as peculiaridades dos contextos de produção e recepção de cada uma delas, a fim de examinar as diferenças no que se refere ao tratamento dado às questões femininas nas obras citadas. Para fundamentar teoricamente o trabalho, recorremos a pesquisadores que se debruçaram sobre os estudos de tradução e adaptação, como Hermans (1992 e Lefevere (1992, e sobre o estudo da comédia grega, como Pompeu (1997 e Oliveira e Silva (1991. Uma vez que os contextos de produção e recepção das obras são distintos, as escolhas feitas durante a elaboração dessas narrativas também se diferenciam, o que aponta para um processo de reescritura do enredo. Os resultados demonstram que a obra cinematográfica, devido ao contexto no qual se insere, debate a condição feminina de modo diverso da comédia: enquanto a comédia aristofânica aborda a temática da mulher para discutir sobre a manutenção da pólis, o filme acolhe pontos de discussão importantes para o próprio movimento feminista e discute a opressão que o patriarcado impõe às mulheres

  13. Correlates of previous couples’ HIV counseling and testing uptake among married individuals in three HIV prevalence strata in Rakai, Uganda

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    Joseph K. B. Matovu

    2015-06-01

    Full Text Available Background: Studies show that uptake of couples’ HIV counseling and testing (couples’ HCT can be affected by individual, relationship, and socioeconomic factors. However, while couples’ HCT uptake can also be affected by background HIV prevalence and awareness of the existence of couples’ HCT services, this is yet to be documented. We explored the correlates of previous couples’ HCT uptake among married individuals in a rural Ugandan district with differing HIV prevalence levels. Design: This was a cross-sectional study conducted among 2,135 married individuals resident in the three HIV prevalence strata (low HIV prevalence: 9.7–11.2%; middle HIV prevalence: 11.4–16.4%; and high HIV prevalence: 20.5–43% in Rakai district, southwestern Uganda, between November 2013 and February 2014. Data were collected on sociodemographic and behavioral characteristics, including previous receipt of couples’ HCT. HIV testing data were obtained from the Rakai Community Cohort Study. We conducted multivariable logistic regression analysis to identify correlates that are independently associated with previous receipt of couples’ HCT. Data analysis was conducted using STATA (statistical software, version 11.2. Results: Of the 2,135 married individuals enrolled, the majority (n=1,783, 83.5% had been married for five or more years while (n=1,460, 66% were in the first-order of marriage. Ever receipt of HCT was almost universal (n=2,020, 95%; of those ever tested, (n=846, 41.9% reported that they had ever received couples’ HCT. There was no significant difference in previous receipt of couples’ HCT between low (n=309, 43.9%, middle (n=295, 41.7%, and high (n=242, 39.7% HIV prevalence settings (p=0.61. Marital order was not significantly associated with previous receipt of couples’ HCT. However, marital duration [five or more years vis-à-vis 1–2 years: adjusted odds ratio (aOR: 1.06; 95% confidence interval (95% CI: 1.04–1.08] and

  14. Inference of strata separation and gas emission paths in longwall overburden using continuous wavelet transform of well logs and geostatistical simulation

    Science.gov (United States)

    Karacan, C. Özgen; Olea, Ricardo A.

    2014-06-01

    Prediction of potential methane emission pathways from various sources into active mine workings or sealed gobs from longwall overburden is important for controlling methane and for improving mining safety. The aim of this paper is to infer strata separation intervals and thus gas emission pathways from standard well log data. The proposed technique was applied to well logs acquired through the Mary Lee/Blue Creek coal seam of the Upper Pottsville Formation in the Black Warrior Basin, Alabama, using well logs from a series of boreholes aligned along a nearly linear profile. For this purpose, continuous wavelet transform (CWT) of digitized gamma well logs was performed by using Mexican hat and Morlet, as the mother wavelets, to identify potential discontinuities in the signal. Pointwise Hölder exponents (PHE) of gamma logs were also computed using the generalized quadratic variations (GQV) method to identify the location and strength of singularities of well log signals as a complementary analysis. PHEs and wavelet coefficients were analyzed to find the locations of singularities along the logs. Using the well logs in this study, locations of predicted singularities were used as indicators in single normal equation simulation (SNESIM) to generate equi-probable realizations of potential strata separation intervals. Horizontal and vertical variograms of realizations were then analyzed and compared with those of indicator data and training image (TI) data using the Kruskal-Wallis test. A sum of squared differences was employed to select the most probable realization representing the locations of potential strata separations and methane flow paths. Results indicated that singularities located in well log signals reliably correlated with strata transitions or discontinuities within the strata. Geostatistical simulation of these discontinuities provided information about the location and extents of the continuous channels that may form during mining. If there is a gas

  15. Origin of natural waters and gases within the Upper Carboniferous coal-bearing and autochthonous Miocene strata in South-Western part of the Upper Silesian Coal Basin, Poland

    International Nuclear Information System (INIS)

    Kotarba, Maciej J.; Pluta, Irena

    2009-01-01

    The molecular and stable isotope compositions of coalbed gases from the Upper Carboniferous strata and natural gases accumulated within the autochthonous Upper Miocene Skawina Formation of the Debowiec-Simoradz gas deposit were determined, as well as the chemical and stable isotope compositions of waters from the Skawina Formation and waters at the top of the Upper Carboniferous strata of the Kaczyce Ridge (the abandoned 'Morcinek' coal mine) in the South-Western part of the Upper Silesian Coal Basin. Two genetic types of natural gases within the Upper Carboniferous coal-bearing strata were identified: thermogenic (CH 4 , small amounts of higher gaseous hydrocarbons, and CO 2 ) and microbial (CH 4 , very small amounts of ethane, and CO 2 ). Thermogenic gases were generated during the bituminous stage of coalification and completed at the end of the Variscan orogeny. Degassing (desorption) of thermogenic gases began at the end of late Carboniferous until the late Miocene time-period and extended to the present-day. This process took place in the Upper Carboniferous strata up to a depth of about 550 m under the sealing Upper Miocene cover. A primary accumulation zone of indigenous, thermogenic gases is present below the degassing zone. Up to 200 m depth from the top of the Upper Carboniferous strata, within the weathered complex, an accumulation zone of secondary, microbial gas occurs. Waters within these strata are mainly of meteoric origin of the infiltration period just before the last sea transgression in the late Miocene and partly of marine origin having migrated from the Upper Miocene strata. Then, both methanogenic archaebacteria and their nutrients were transported by meteoric water into the near-surface Carboniferous strata where the generated microbial CH 4 saturated coal seams. Waters within the Miocene strata of the Debowiec-Simoradz and Zablocie are of marine origin, and natural gases accumulated within autochthonous Miocene strata of the Debowiec

  16. Age and kinematics of ductile deformation in the Cerro Durazno area, NW Argentina: Significance for orogenic processes operating at the western margin of Gondwana during Ordovician-Silurian times

    OpenAIRE

    M. I. Wegmann; U. Riller; F. D. Hongn; Johannes Glodny; Onno Oncken

    2008-01-01

    The Cerro Durazno Pluton belongs to a suite of Paleozoic granitoid intrusions in NWArgentina, that are central for understanding the tectonic setting of the western margin of Gondwana in Ordovician and Silurian times. The pluton and its host rocks were tectonically overprinted by metamorphic mineral shape fabrics formed under middle greenschist-facies metamorphic conditions and associated with the nearby Agua Rosada Shear Zone. Kinematic analysis of the shear zone based on the geometric relat...

  17. 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

  18. Gradients in the carbon isotopic composition of Ordovician shallow water carbonates: A potential pitfall in estimates of ancient CO2 and O2

    Science.gov (United States)

    Saltzman, Matthew R.; Edwards, Cole T.

    2017-04-01

    The carbon isotopic composition of the global dissolved inorganic carbon (DIC) reservoir is best estimated from open ocean pelagic carbonate sediments (δ13Ccarb). However, this is not practical for most of geologic time because seafloor subduction has removed the pre-Jurassic record and these time periods may have lacked planktonic calcifying organisms, and therefore shallow water carbonate platform or periplatform sediments are utilized. Shallow water deposits are susceptible to a wide range of post-depositional alteration processes and syn-depositional controls on δ13Ccarb that include carbonate mineralogy, water mass restriction, and a host of related variables (e.g., pH, temperature, organic decomposition, evaporation and CO2 solubility) that can produce local gradients in DIC. The degree to which shallow water δ13C curves diverge from open marine deposits may be critical to understanding how well global carbon cycle isotope mass balance models can predict organic carbon burial rates, but documentation of such divergence is often hindered by factors that limit chronostratigraphic correlation in restricted water masses (e.g., endemic faunas). Here we integrate strontium isotope (87Sr/86Sr) stratigraphy and biostratigraphy to compare δ13C curves in a case study along a depth transect in Middle-Late Ordovician carbonate platform settings. The restricted tidal flat and more open marine deposits are offset by a maximum of ∼2‰ during sea level drop and ∼0‰ during highstand flooding of the platform. Global carbon cycle models such as GEOCARBSULF use published δ13Ccarb curves to drive organic carbon burial rates under the assumption that δ13Ccarb reflects a global seawater signal. We show here the potential pitfalls of using a published δ13Ccarb curve that violates this global assumption. For the 460 million year Middle-Late Ordovician time bin in GEOCARBSULF, improper usage of our locally depleted δ13C curve to drive global organic carbon burial would

  19. Characterization of Shiga Toxin-Producing Escherichia coli Isolated from Ground Beef Collected in Different Socioeconomic Strata Markets in Buenos Aires, Argentina

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    Patricia Llorente

    2014-01-01

    Full Text Available Consumption of raw/undercooked ground beef is the most common route of transmission of Shiga toxin-producing E. coli (STEC. The aim of the study was to determine the STEC contamination level of the ground beef samples collected in 36 markets of different socioeconomic strata in Buenos Aires, Argentina, and the characterization of the isolated strains. Ninety-one out of 252 (36.1% samples were stx+. Fifty-seven STEC strains were recovered. Eleven STEC strains belonged to O157 serogroup, and 46 to non-O157 serogroups. Virulence markers of the 57 STEC were stx1, 5.3% (3/57; stx2, 86.0% (49/57; stx1/stx2, 8.8% (5/57; ehxA, 61.4% (35/57; eae, 26.3% (15/57; saa, 24.6% (14/57. Shiga toxin subtypes were stx2, 31.5% (17/54; stx2c-vhb, 24.1% (13/54; stx2c-vha, 20.4% (11/54; stx2/stx2c-vha, 14.8% (8/54; stx2/stx2c-vhb, 5.6% (3/54; stx2c-vha/vhb, 3.7% (2/54. Serotypes O178:H19 and O157:H7 were prevalent. Contamination rate of STEC in all strata was high, and the highest O157 contamination was observed at low strata at several sampling rounds. Persistence of STEC was not detected. Sixteen strains (28.1% were resistant to ampicillin, streptomycin, amikacin, or tetracycline. The STEC contamination level of ground beef could vary according to the sociocultural characteristics of the population.

  20. Preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for samples from Upper and Lower Cretaceous strata, Maverick Basin, south Texas

    Science.gov (United States)

    Hackley, Paul C.; Dennen, Kristin O.; Gesserman, Rachel M.; Ridgley, Jennie L.

    2009-01-01

    The Lower Cretaceous Pearsall Formation, a regionally occurring limestone and shale interval of 500-600-ft maximum thickness (Rose, 1986), is being evaluated as part of an ongoing U.S. Geological Survey (USGS) assessment of undiscovered hydrocarbon resources in onshore Lower Cretaceous strata of the northern Gulf of Mexico. The purpose of this report is to release preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for Pearsall Formation, Glen Rose Formation, Hosston Formation, Austin Group, and Eagle Ford Group samples from the Maverick Basin in south Texas in order to aid in the characterization of these strata in this area. The preliminary nature of this report and the data contained herein reflect that the assessment and characterization of these samples is a work currently in progress. Pearsall Formation subdivisions are, in ascending stratigraphic order, the Pine Island Shale, James Limestone, and Bexar Shale Members (Loucks, 2002). The Lower Cretaceous Glen Rose Formation is also part of the USGS Lower Cretaceous assessment and produces oil in the Maverick Basin (Loucks and Kerans, 2003). The Hosston Formation was assessed by the USGS for undiscovered oil and gas resources in 2006 (Dyman and Condon, 2006), but not in south Texas. The Upper Cretaceous Austin Group is being assessed as part of the USGS assessment of undiscovered hydrocarbon resources in the Upper Cretaceous strata of the northern Gulf of Mexico and, along with the Upper Cretaceous Eagle Ford Group, is considered to be an important source rock in the Smackover-Austin-Eagleford Total Petroleum System (Condon and Dyman, 2006). Both the Austin Group and the Eagle Ford Group are present in the Maverick Basin in south Texas (Rose, 1986).

  1. U-Pb Geochronology of non-marine Upper Triassic strata of the Colorado Plateau (western North America): implications for stratigraphic correlation and paleoenvironmental reconstruction

    Science.gov (United States)

    Rasmussen, C.; Mundil, R.; Irmis, R. B.; Keller, C. B.; Giesler, D.; Gehrels, G. E.

    2017-12-01

    The Triassic is a critical period in Earth history that witnessed the origin of modern ecosystems and frequent climate fluctuations, as well as major environmental events such as flood basalt volcanism and bolide impacts. The Chinle Formation contains a primary non-marine archive for past ecosystems in North America due to its fossil richness and well-studied sedimentology. Moreover, within these highly fossiliferous strata, a biotic turnover has been reported that has been hypothesized to coincide with one or more of the aforementioned environmental events. Unfortunately, few radioisotopic ages have been published for the Late Triassic, limiting our ability for lithological and paleoenvironmental correlations. In addition, the superposition of the Chinle Formation remains illusive due to frequent lateral facies changes and discontinuous outcrops across the Colorado Plateau. The 520 m long core 1A of the Colorado Plateau Coring Project from Petrified Forest National Park (PFNP) (Arizona) provides, for the first time, a continuous section of these early Mesozoic sedimentary strata. Many of the sand- and siltstones from this continuous succession throughout most of the Upper Triassic Chinle Formation contain euhedral zircons suitable for U-Pb analyses. We analyzed >300 crystals each from 10 samples using LA-ICPMS; these results indicated abundant Late Triassic crystals that appear to be closely associated with the depositional age of the host rock. We then selected the youngest grains from these samples to obtain precise CA-TIMS U-Pb single zircon ages in order to constrain the maximum depositional ages (using quantitative methods) of these formations. We are able to revise the proposed time scale (based on outcrop samples) for Upper Triassic strata at PFNP and evaluate whether the biotic turnover observed within the Sonsela Member of these strata coincides with the Manicouagan bolide impact event. This revised chronostratigraphic framework allows intercalibration

  2. Integration of Sedimentology,Petrophysics and Statistics for Characterizing the Reservoir Heterogeneity of the Late Ordovician Sarah Formation, Central Saudi Arabia

    Science.gov (United States)

    El-Deek, Islam; Abdullatif, Osman; Korvin, Gabor; Al-Ramadan, Khalid

    2014-05-01

    The first glaciogenic event in the Arabian Peninsula is represented by the Late Ordovician Sarah Formation. Sarah Formation is outcropping in areas of central and northern Arabia bordering the Arabian Shield, while it occupies several sub-basinal areas in the subsurface. The glacio-fluvial Sarah Formation is considered as an important tight gas reservoir target. This study uses the outcrop analog of the Sarah Formation to characterize the reservoir heterogeneity of the paleovalleys based on sedimentological, petrophysical, and statistical approaches. Facies types and architectural elements were identified within several paleovalleys of the Sarah Formation. The study indicated variability in texture, composition, sandstone type, facies, geometry and architecture at outcrop scale. Outcrop relationships also showed vertical and lateral facies change with other Paleozoic formations. The integration of field and laboratory data helped identifying the heterogeneity within Sarah paleovalleys. The reservoir quality trends in the Sarah Formation show variations that might be due to the controls of facies, depositional environments, and paleogeography. Three measures of heterogeneity were applied on the petrophysical data for various paleovalleys of the Sarah Formation. Those measures are: the coefficient of variation, Dykstra-Parsons, and Lorenz coefficients.The coefficient of variation values indicate extremely heterogeneous distribution. Dykstra-Parsons coefficient values suggest very to extremely heterogeneous reservoirs. Lorenz coefficients show good correlation with Dykstra-Parsons coefficient for Sarah paleovalleys. The studied heterogeneity measures indicate that Sarah paleovalleys represent very to extremely heterogeneous reservoirs.

  3. Multiphase Calcite Cementation and Fluids Evolution of a Deeply Buried Carbonate Reservoir in the Upper Ordovician Lianglitag Formation, Tahe Oilfield, Tarim Basin, NW China

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    Jiaqing Liu

    2017-01-01

    Full Text Available Oil and gas have been found in the Upper Ordovician Lianglitag Formation carbonates in the Tahe Oilfield, Tarim Basin, NW China. This study documents the origin of diagenetic fluids by using a combination of petrology, SIMS, fluid inclusion, and radiogenic isotope analysis. Six stages of calcite cements were revealed. C1-C2 formed in marine to early burial environments. C3 has relatively low δ18OVPDB values (−8.45‰ to −6.50‰ and likely has a meteoric origin. Meteoric water probably fluxed into aquifers during the Early Paleozoic and Late Paleozoic uplift. C4 has δ18OVPDB values typically 3‰ higher than those of C3, and probably formed during shallow burial. C5 displays relatively negative δ18OVPDB values (−8.26‰ to −5.12‰, and the moderate-to-high fluid-inclusion temperatures imply that it precipitated in burial environments. C6 shows homogenization temperatures (up to 200°C higher than the maximum burial and much lower salinities (<10.61 wt% NaCl, which may suggest that the fluid was deeply recycled meteoric water. The average 87Sr/86Sr ratios of fracture- and vug-filling calcite cements are much higher, indicative of incorporation of radiogenic Sr. Caves and fractures constitute the dominant reservoir spaces. A corresponding diagenesis-related reservoir evolution model was established that favors exploration and prediction.

  4. Typology and fossil assemblage of Sandbian (Ordovician ‘baksteenkalk’: an erratic silicified limestone of Baltic origin from the northeastern Netherlands and adjacent areas of Germany

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    Percy van Keulen

    2017-11-01

    Full Text Available This study seeks to describe ‘baksteenkalk’, an erratic silicified bioclastic carbonate of the Upper Sandbian from the eastern part of the Netherlands. To date, baksteenkalk has received little attention among palaeontologists. This is to be regretted on two grounds. First, baksteenkalk contains a varied fossil flora and fauna comprising many species, several of which are not or only rarely found in coeval rocks. Second, owing to a complicated silicification process, fossils, in particular algae, have preserved exceptional anatomical details. The primary aim of this study is to arouse the interest of professional, in particular, Estonian, palaeontologists in baksteenkalk. Based on lithology and fossil assemblage (most conspicuously, with regard to the algal flora, two basic types of baksteenkalk are distinguished. A list of species, differentiated for both types, is provided. It is argued that baksteenkalk reflects the ecology of a shallow, subtropical, epicontinental sea. The distribution of erratics, facies and fossil content point to an origin within the North Estonian Confacies Belt, probably west of Estonia. Baksteenkalk survived as an erratic because it was already silicified at its place of origin. A potential source of silica may have been Upper Ordovician bentonite layers. The causes and mechanisms of the silicifi­cation process which gave shape to baksteenkalk are not yet understood, however. The palaeontology of baksteenkalk is compared with that of two other erratic Sandbian silicified carbonates of Baltic origin: German Backsteinkalk and ‘Lavender-blue Hornstein’.

  5. The nature of Ordovician limestone-marl alternations in the Oslo-Asker District (Norway): witnesses of primary glacio-eustasy or diagenetic rhythms?

    Science.gov (United States)

    Amberg, Chloé E. A.; Collart, Tim; Salenbien, Wout; Egger, Lisa M.; Munnecke, Axel; Nielsen, Arne T.; Monnet, Claude; Hammer, Øyvind; Vandenbroucke, Thijs R. A.

    2016-01-01

    Ordovician limestone-marl alternations in the Oslo-Asker District have been interpreted as signaling glacio-eustatic lowstands, which would support a prolonged “Early Palaeozoic Icehouse”. However, these rhythmites could alternatively reflect differential diagenesis, without sedimentary trigger. Here, we test both hypotheses through one Darriwilian and three Katian sections. Our methodology consists of a bed-by-bed analysis of palynological (chitinozoan) and geochemical (XRF) data, to evaluate whether the limestone/marl couplets reflect an original cyclic signal. The results reveal similar palynomorph assemblages in limestones and marls. Exceptions, which could be interpreted as reflecting palaeoclimatological fluctuations, exist at the species level: Ancyrochitina bornholmensis seems to be more abundant in the marl samples from the lower Frognerkilen Formation on Nakkholmen Island. However, these rare cases where chitinozoans differ between limestone/marl facies are deemed insufficient for the identification of original cyclicity. The geochemical data show a near-perfect correlation between insoluble elements in the limestone and the marls, which indicates a similar composition of the potential precursor sediment, also in the Frognerkilen Formation. This is consistent with the palynological data. Although an original cyclic pattern could still be recorded by other, uninvestigated parameters, our palaeontological and geochemical data combined do not support the presence of such a signal.

  6. Pollen-ovule relation in Adesmia tristis and reflections on the seed–ovule ratio by interaction with pollinators in two vertical strata

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    NADILSON R. FERREIRA

    2014-09-01

    Full Text Available The vertical distribution of pollinators is an important component in the foraging pattern of plants strata, and it influences the reproductive system (pollen/ovule ratio and seed/ovule ratio. Niches in two different strata from Adesmia tristis Vogel were evaluated in these aspects. This plant is an endemic shrub from the Campos de Cima da Serra in Southern Brazil. The studies were carried out from January 2010, to January 2011, at Pró-Mata/PUCRS (Catholic University of Rio Grande do Sul (29°27′-29°35′S and 50°08′-50°15′W, São Francisco de Paula, sate of Rio Grande do Sul, Brazil. Breeding system of A. tristis is mandatory allogamy. The vertical profile in A. tristis has differentiated foraging niches among the most common pollinators. Bees of Megachile genus forage in the upper stratum, and representative bees of the Andrenidae family explore the lower stratum. The upper stratum of the vertical profile had more contribution to seed production. Adesmia tristis showed evidence of pollination deficit.

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

    Science.gov (United States)

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

    2018-04-01

    Shale gas and coalbed methane (CBM) are both considered unconventional natural gas and are becoming increasingly important energy resources. In coal-bearing strata, coal and shale are vertically adjacent as coal and shale are continuously deposited. Research on the reservoir characteristics of coal-shale sedimentary sequences is important for CBM and coal-bearing shale gas exploration. In this study, a total of 71 samples were collected, including coal samples (total organic carbon (TOC) content >40%), carbonaceous shale samples (TOC content: 6%-10%), and shale samples (TOC content gas reservoirs in coal-bearing strata. The results indicate that in the coal-shale sedimentary sequence, the proportion of shale is the highest at 74% and that of carbonaceous shale and coal are 14% and 12%, respectively. The porosity of all measured samples demonstrates a good positive relationship with TOC content. Clay and quartz also have a great effect on the porosity of shale samples. According to the FE-SEM image technique, nanoscale pores in the organic matter of coal samples are much more developed compared with shale samples. For shales with low TOC, inorganic minerals provide more pores than organic matter. In addition, TOC content has a positive relationship with methane adsorption capacity, and the adsorption capacity of coal samples is more sensitive than the shale samples to temperature.

  8. 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

  9. 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

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    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.

  10. Age and kinematics of ductile deformation in the Cerro Durazno area, NW Argentina: Significance for orogenic processes operating at the western margin of Gondwana during Ordovician - Silurian times

    Science.gov (United States)

    Wegmann, Maja I.; Riller, Ulrich; Hongn, Fernando D.; Glodny, Johannes; Oncken, Onno

    2008-07-01

    The Cerro Durazno Pluton belongs to a suite of Paleozoic granitoid intrusions in NW-Argentina, that are central for understanding the tectonic setting of the western margin of Gondwana in Ordovician and Silurian times. The pluton and its host rocks were tectonically overprinted by metamorphic mineral shape fabrics formed under middle greenschist-facies metamorphic conditions and associated with the nearby Agua Rosada Shear Zone. Kinematic analysis of the shear zone based on the geometric relationship between individual segments of the shear plane and principal axes of mineral fabric ellipsoids indicates reverse-sense of shear with a minor component of left-lateral displacement. This is compatible with the kinematics of other ductile deformation zones in this area, collectively forming a network, which accomplished orogen-parallel extension in addition to vertical thickening. Using the Rb-Sr isotopic system, an undeformed pegmatite dike of the Cerro Durazno Pluton was dated at 455.8 ± 3.6 Ma and mineral fabrics of the Agua Rosada Shear Zone formed at middle greenschist-facies metamorphism gave deformation ages of 437.0 ± 3.8 Ma and ⩽428.4 ± 4.5 Ma. Thus, tectonic overprint at low metamorphic grade occurred about 20-30 Ma after terminal magmatism in the Cerro Durazno area. Our data from the Cerro Durazno area and regional considerations suggest that the western margin of Gondwana was characterized by orogen-parallel extension in addition to crustal thickening as well as episodes of magmatism and ductile deformation that varied greatly in time and space.

  11. Nature and regional significance of unconformities associated with the Middle Ordovician Hagan K-bentonite complex in the North American midcontinent

    Science.gov (United States)

    Kolata, Dennis R.; Huff, W.D.; Bergstrom, Stig M.

    1998-01-01

    Stratal patterns of the Middle Ordovician Hagan K-bentonite complex and associated rocks show that the Black River-Trenton unconformity in the North American midcontinent formed through the complex interplay of eustasy, sediment accumulation rates, siliciclastic influx, bathymetry, seawater chemistry, and perhaps local tectonic uplift. The unconformity is diachronous and is an amalgamated surface that resulted from local late Turinian lowstand exposure followed by regional early Chatfieldian transgressive drowning and sediment starvation. The duration of the unconformity is greatest in southern Wisconsin, northern Illinois, and northern Indiana, where the Deicke and Millbrig K-bentonite Beds converge at the unconformity. On the basis of published isotopic ages for the Deicke and Millbrig beds, it is possible that in these regions erosion and non-deposition spanned a period of as much as 3.2 m.y. Two broad coeval depositional settings are recognized within the North American midcontinent during early Chatfieldian time. 1) An inner shelf, subtidal facies of fossiliferous shale (Spechts Ferry Shale Member and Ion Shale Member of the Decorah Formation) and argillaceous lime mudstone and skeletal wackestone (Guttenberg and Kings Lake Limestone Members) extended from the Canadian shield and Transcontinental arch southeastward through Minnesota, Wisconsin, Iowa, and Missouri. 2) A seaward, relatively deep subtidal, sediment-starved, middle shelf extended eastward from the Mississippi Valley region to the Taconian foreland basins in the central and southern Appalachians and southward through the pericratonic Arkoma and Black Warrior basins. In the inner shelf region, the Black River-Trenton unconformity is a composite of at least two prominent hardground omission surfaces, one at the top of the Castlewood and Carimona Limestone Members and the other at the top of the Guttenberg and Kings Lake Limestone Members, both merging to a single surface in the middle shelf region

  12. Strain analysis of Late Ordovician tectonic events in the In-Tahouite and Tamadjert Formations (Tassili-n-Ajjers area, Algeria)

    Science.gov (United States)

    Zazoun, Réda Samy; Mahdjoub, Yamina

    2011-05-01

    The Tassili-n-Ajjers area in southern Algeria is located in the south-east of the Saharan platform. It is bounded to the east by the Tihemboka N-S trending structural system, the Hoggar shield to the south and to the north by the Illizi Basin. During the Palaeozoic, the Saharan Platform was part of the northern passive margin of the Gondwana supercontinent and the tectono-stratigraphic evolution of sedimentary systems in the Algerian Sahara was typical of the Gondwana stable cratonic platform. During the Late Ashgill (Hirnantian), the North African platform was located near the South Pole and an icecap developed over much of Africa and South America. Field observations, in the study area, together with integrated strain analysis and previous studies provide evidence for a number of Late Ordovician deformation phases. An extensional event of probably Late Caradoc-Early Ashgill age (?) was associated with the development of planar domino-style normal faults and listric faults that occurred prior to the infill of glacial palaeovalleys. This is observed in the pre-glacial In-Tahouite Formation. Glaciotectonic over the Tassilli-n-Ajjers is related to the Late Ashgillian (Hirnantian stage) Taconic event. Probably, the Taconic unconformity is a combination of traditional tectonic movements and glaciotectonics. Many soft-sediment deformation structures are attributed to glaciotectonic process. A systematic description of these deformation structures and strain analysis show that there are two types of deformation, pure shear at the top of the Hirnantian syn-glacial Tamadjert Formation and simple shear in the basal part and there are two types of glaciotectonic deformation. The first type at the base is the subglacial deformation and is characterized by simple shear strain and extensional tectonics. The second type at the top is characterized by pure shear strain and compressional tectonics and consists on proglacial deformation. The glacial palaeovalleys show a gravity

  13. 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.

  14. Palaeoclimate evolution across the Cretaceous-Palaeogene boundary in the Nanxiong Basin (SE China) recorded by red strata and its correlation with marine records

    Science.gov (United States)

    Ma, Mingming; Liu, Xiuming; Wang, Wenyan

    2018-03-01

    The climate during the Cretaceous Period represented one of the greenhouse states of Earth's history. Significant transformation of climate patterns and a mass extinction event characterised by the disappearance of dinosaurs occurred across the Cretaceous-Palaeogene boundary. However, most records of this interval are derived from marine sediments. The continuous and well-exposed red strata of the Nanxiong Basin (SE China) provide ideal material to develop continental records. Considerable research into stratigraphic, palaeontological, chronologic, palaeoclimatic, and tectonic aspects has been carried out for the Datang profile, which is a type section of a non-marine Cretaceous-Palaeogene stratigraphic division in China. For this study, we reviewed previous work and found that (1) the existing chronological framework of the Datang profile is flawed; (2) precise palaeoclimatic reconstruction is lacking because of the limitations of sampling resolution (e.g. carbonate samples) and/or the lack of efficient proxies; and (3) comparisons of climate changes between marine and continental records are lacking. To resolve these problems, detailed field observations and sampling, as well as environmental magnetic and rare earth element (REE) measurements, were carried out. The results show that (1) more accurate ages of the Datang profile range from 72 to 62.8 Ma based on a combination of the most recently published radiometric, palaeontological, and palaeomagnetic ages; (2) there is considerable evidence of palaeosol generation, which indicates that the red strata formed in a long-term hot, oxidising environment that lacked underwater conditions; (3) haematite was the dominant magnetic mineral in the red strata, and the variation trend of magnetic susceptibility was consistent with the oxygen isotope records from deep-sea sediments, which indicates that the content of haematite was controlled by the global climate; and (4) the palaeoclimate changes from 72 to 62.8 Ma in the

  15. Paleo-ocean environments before and after the Ordovician glaciation and the correlation with heterogeneous marine black shale: a stratigraphic case study of Wufeng-Longmaxi formation in Fuling, Sichuan basin, SW China

    Science.gov (United States)

    Lu, Yangbo; Hao, Fang; Lu, Yongchao

    2017-04-01

    The discovery of Fuling gas field in the Sichuan basin led China shale gas exploration to an unprecedented boom. The most important shale gas plays are the upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation which demonstrate intriguing characteristics which are comprising of stable regional distribution, high abundance of organic matter, high thermal maturity and high brittle mineral content etc. As the Ordovician-Silurian transition was a critical interval in Earth's history marked by dramatic climatic, oceanic, and biological turnovers; these two advantageous organic rich shale deposited before and after Hirnantian glaciation are showing differences in many aspects. In this study, the stratigraphy and lithofacies within the stratigraphy framework of the upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Fuling were quantitatively analyzed based on outcrops, cores, well logs data, and geochemical proxies. A total of three third-order sequences were divided based on the recognition of four third-order boundaries. The Wufeng Formation is equivalent to a third-order sequence and is subdivided into a transgressive system tract (TST) (black shale of lower Wufeng Formation) and a highstand system tract (HST) (Guanyinqiao Member of upper Wufeng Formation). Long-1 Member is equivalent to a third-order sequence and is subdivided into a TST, an early highstand system tract (EHST) and a late highstand system tract (LHST); Long-2 and Long-3 Member are combined to be one third-order sequence and is subdivided into a lowstand system tract (LST), a TST and a HST. Sequence development and sedimentary environment characteristics were analyzed within each system tract unit. TOC% was correlated to V/Cr and EF-Ni respectively within each system tract unit, suggesting paleoproductivity and water redox condition are the main controlling factors of organic enrichment and its preservation. The heterogeneity in shale lithofacies throughout the

  16. The comparison of strata-bound massive sulfide deposits using the fuzzy-linguistic diagnosis of the Zlaté Hory deposits, Czechoslovakia, as an example

    Science.gov (United States)

    Patočka, F.; Vrba, J.

    1989-07-01

    The Zlaté Hory ore deposits — as an example of volcanogenic, strata-bound, massive, base-metal sulfides occurring in the Devonian formations of the Jeseníky Mts. — are compared with distinctive Phanerozoic types representing this type of ore deposit, i.e., with Kuroko-type, Rosebery-type, Besshi-type and Cyprus-type deposits. The results of comparison performed with fuzzy-linguistic diagnosis indicate close resemblance of the Zlaté Hory deposits to Rosebery-type massive sulfides with regard to primary features; however, individual features point to certain original similarity with Kuroko-type deposits, too. The metamorphic history of the ore deposits studied was similar to that of the Rosebery and Besshi types.

  17. The characteristics of soda metasomatite type uranium mineralization for proterozoic strata in the central-southern part of Kang-Dian earth's axis

    International Nuclear Information System (INIS)

    Qian Farong

    1995-12-01

    The uranium mineralization for Proterozoic strata in the central-southern part of Kang-Dian earth's axis can be divided into four typy (sandstone, soda metasomatite, proterozoic epimetamorphics and quartzite). The soda metasomatite type is the dominant type of uranium mineralization and has the prospecting potential in the area. The characteristics of this type uranium mineralization and the problems of metallogenesis are discussed. Soda metasomatite type uranium mineralization is controlled by soda metasomatite and structure. Uranium exists mainly in the forms of minerals (pitchblende, uranate). Its cell parameter is high and oxygenated coefficient is low, belonging to moderate-low temperature hydrothermal origin. The metallogenetic materials originated from deep-seated crust and country rocks. The metallogenetic solution includes a great quantity of atmospheric water, besides hydrothermal solution from deep-seated crust. The metallogene underwent the two stages i.e. Jinnin and Chengjiang. (4 tabs., 3 figs.)

  18. Remagnetization of Cretaceous forearc strata on Santa Margarita and Magdalena Islands, Baja California Sur: Implications for northward transport along the California margin

    Science.gov (United States)

    Hagstrum, Jonathan T.; Sedlock, Richard L.

    1998-12-01

    Paleomagnetic data for two sections of Cretaceous forearc strata with different structural attitudes on Santa Margarita and Magdalena Islands in Baja California Sur, Mexico, indicate that these rocks have been remagnetized, probably during the late Cenozoic. The in situ paleomagnetic directions, however, are similar to data from other Cretaceous rocks on peninsular California with unexpectedly shallow inclinations and easterly declinations. These data have been interpreted as indicating either northward tectonic transport (10°-15° of latitude) and clockwise rotation (>20°) or compaction shallowing of magnetic inclinations in sedimentary rocks combined with southwestward tilting of plutonic rocks. The available paleomagnetic data for Cretaceous forearc strata in southern and Baja California can be divided into three groups: (1) sections with normal-polarity magnetizations that fail fold tests and are remagnetized, (2) sections with normal-polarity magnetizations with no or inconclusive fold tests that may or may not be remagnetized, and (3) sections with both normal-and reversed-polarity intervals where pervasive remagnetization has not occurred. Other rocks of the Mesozoic Great Valley Group, Coast Range ophiolite, and Franciscan Complex in California also have secondary magnetizations with directions similar to younger geomagnetic field directions. Although these widespread remagnetizations could have variable local causes, we propose regional burial and uplift, related to changes in subduction parameters, as a possible explanation. Two episodes of remagnetization are apparent: one in the Late Cretaceous and a second in the late Cenozoic. On the other hand, the unremagnetized and apparently reliable data from sedimentary and plutonic rocks on the Baja Peninsula consistently indicate northward translation (14° ± 3°) and clockwise rotation (29° ± 8°) with respect to North America since the Late Cretaceous.

  19. Ordovician metamorphism in the Sierras Pampeana: New U-Pb SHRIMP ages in Central-East Valle Fertil and the Velasco batholith

    International Nuclear Information System (INIS)

    Rapela, C.W; Pankhurst, R.J; Baldo, E; Casquet, C.; Galindo, C; Fanning, C.M; Saavedra, J

    2001-01-01

    Magmatic activity, during which extensive I- and S-type granitoids were emplaced in the Famatinian belt and synchronous, though sparse, TTG plutons in the Pampean belt, preceded the accretion of the Precordillera terrane (PT) to the proto-Pacific margin of South America. These three types of granitoid were mainly emplaced in Early Ordovician times (470 90 Ma, Pankhurst et al., 2001). However, little is known about the timing and characteristics of regional metamorphism during the Famatinian orogeny. A key transect in this study is at 30 o 30 31 o 40 , where Grenvillian basement units of the PT are separated by the Bermejo valley from high-grade rocks of the Sierra de Valle Fertil. Geochronological studies have been carried out in the Sierra de Pie de Palo (PT), on the western side of the transect, by Ramos et al. (1998) and Casquet et al. (2001). We are now able to characterise metamorphism on the eastern side of the transect, i.e. the Gondwana margin. To this end we are presenting new U-Pb SHRIMP geochronological studies of western Sierra de Valle Fertil (Baldo et al., 2001), and central-eastern Sierra de Valle Fertil and Sierra de Velasco (this paper). The geology of the central and eastern sectors of the Sierra de Valle Fertil is dominated by a metaluminous sequence of hornblende-biotite tonalites/granodiorites, and suites of troctolitic, noritic and hornblende gabbros emplaced in high-grade metapelites, marbles and amphibolites. The locations of the three samples selected for the isotopic study SVF-3131 is a garnet migmatite composed of Grt + Bt + Pl + Qtz, with Zrn, Mnz, Ap as accessories (mineral symbols after Kretz, 1983). SVF-573 is a cordierite-garnet diatexitic migmatite: Crd (Mg 77-79) + Grt (Alm 57-69, Py 27-32) + Bt (TiO 2 = 3.2-4.5%) + Sil + Pl (An33-35) + Kfs + Qtz; accessories are Spl (included in Grt, ZnO 9-11%), Zrn, Mag, Ilm, Mnz. The widespread occurrence of Crd and Spl in the high-grade rocks indicates that anatexis in central-east Valle Fertil

  20. A reworked Lake Zone margin: Chronological and geochemical constraints from the Ordovician arc-related basement of the Hovd Zone (western Mongolia)

    Science.gov (United States)

    Soejono, Igor; Buriánek, David; Janoušek, Vojtěch; Svojtka, Martin; Čáp, Pavel; Erban, Vojtěch; Ganpurev, Nyamtsetseg

    2017-12-01

    The primary relationships and character of the boundaries between principal lithotectonic domains in the Mongolian tract of the Central Asian Orogenic Belt (CAOB) are still poorly constrained. This brings much uncertainty in understanding of the orogeny configuration and the complete accretionary history. The plutonic Khuurai Tsenkher Gol Complex and the mainly metasedimentary Bij Group represent associated medium- to high-grade basement complexes exposed in the Hovd Zone close to its boundary with the Lake Zone in western Mongolia. The Khuurai Tsenkher Gol Complex is composed of variously deformed acid to basic magmatic rocks intimately associated with the metamorphosed sedimentary and volcanic rocks of the Bij Group. Results of our field work, new U-Pb zircon ages and whole-rock geochemical data suggest an existence of two separate magmatic events within the evolution of the Khuurai Tsenkher Gol Complex. Early to Mid-Ordovician (476 ± 5 Ma and 467 ± 4 Ma protoliths) normal- to high-K calc-alkaline orthogneisses, metadiorites and metagabbros predominate over Mid-Silurian (430 ± 3 Ma) tholeiitic-mildly alkaline quartz monzodiorites. Whereas the geochemical signature of the former suite unequivocally demonstrates its magmatic-arc origin, that of the latter quartz monzodiorite suggests an intra-plate setting. As shown by Sr-Nd isotopic data, the older arc-related magmas were derived from depleted mantle and/or were generated by partial melting of juvenile metabasic crust. Detrital zircon age populations of the metasedimentary rocks together with geochemical signatures of the associated amphibolites imply that the Bij Group was a volcano-sedimentary sequence, formed probably in the associated fore-arc wedge basin. Moreover, our data argue for an identical provenance of the Altai and Hovd domains, overall westward sediment transport during the Early Palaeozoic and the east-dipping subduction polarity. The obvious similarities of the Khuurai Tsenkher Gol Complex

  1. The Sanrafaelic remagnetization revisited: Magnetic properties and magnetofabrics of Cambrian-Ordovician carbonates of the Eastern Precordillera of San Juan, Argentina

    Science.gov (United States)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.; Poiré, Daniel G.

    2017-11-01

    Systematic rock-magnetic and magnetofabric studies were carried out on samples from twenty-three palaeomagnetic sites distributed on the La Laja, Zonda, La Flecha, La Silla and San Juan Formations, which constitute a thick middle Cambrian to early Ordovician carbonate sequence exposed in the Eastern Precordillera of Argentina. Previous palaeomagnetic studies on these rocks showed that this succession is characterized by a recent full overprint in the lower levels and a post-tectonic Permian remagnetization associated to the widespread Sanrafaelic event in the upper part. Our investigation revealed that the fluctuations of the magnetic properties are stratigraphically (lithologically) controlled. Anisotropy of magnetic and anhysteretic susceptibility measurements defined consistent fabrics along the entire section that switch progressively from "inverse", at the bottom, to "normal", at the top, with "intermediate" fabrics occurring mainly at medium levels. Degree of dolomitization significantly affects many rock-magnetic parameters, but appears unrelated to the presence of the Permian remagnetization, which is determined to reside in magnetite despite the complex magnetic mineralogy shown by the studied carbonates. Hysteresis cycles of rocks affected by the Sanrafaelic remagnetization are governed by ferromagnetic fractions showing a clear difference respect to those not affected and characterized by the dominance of paramagnetic or diamagnetic signals. The magnetic fabrics and mineralogical characterization rule out a thermoviscous origin and suggest a chemical remagnetization originated in the authigenic formation of magnetite for the Sanrafaelic overprint. X-ray diffraction analyses indicate that clay minerals are virtually absent in the whole succession with no traces of illite in any sample, discarding burial diagenesis of clay minerals for the origin of the remagnetization. Lack of late Palaeozoic magmatic rocks near the study area difficults correlation of

  2. School Achievement Of Pupils From The Lower Strata In Public, Private Government-Dependent And Private Government-Independent Schools: A Cross-National Test Of The Coleman-Hoffer Thesis

    Science.gov (United States)

    Corten, Rense; Dronkers, Jaap

    2006-01-01

    We consider the question whether pupils from the lower social strata perform better in private government-dependent schools than in public or private-independent schools, using the Programme for International Student Assessment (PISA) 2000 data on European high schools. In the 1980s, Coleman and Hoffer (1987) found in the USA that the performance…

  3. Evaluation of hypotheses for right-lateral displacement of Neogene strata along the San Andreas Fault between Parkfield and Maricopa, California

    Science.gov (United States)

    Stanley, Richard G.; Barron, John A.; Powell, Charles L.

    2017-12-22

    We used geological field studies and diatom biostratigraphy to test a published hypothesis that Neogene marine siliceous strata in the Maricopa and Parkfield areas, located on opposite sides of the San Andreas Fault, were formerly contiguous and then were displaced by about 80–130 kilometers (km) of right-lateral slip along the fault. In the Maricopa area on the northeast side of the San Andreas Fault, the upper Miocene Bitterwater Creek Shale consists of hard, siliceous shale with dolomitic concretions and turbidite sandstone interbeds. Diatom assemblages indicate that the Bitterwater Creek Shale was deposited about 8.0–6.7 million years before present (Ma) at the same time as the uppermost part of the Monterey Formation in parts of coastal California. In the Parkfield area on the southwest side of the San Andreas Fault, the upper Miocene Pancho Rico Formation consists of soft to indurated mudstone and siltstone and fossiliferous, bioturbated sandstone. Diatom assemblages from the Pancho Rico indicate deposition about 6.7–5.7 Ma (latest Miocene), younger than the Bitterwater Creek Shale and at about the same time as parts of the Sisquoc Formation and Purisima Formation in coastal California. Our results show that the Bitterwater Creek Shale and Pancho Rico Formation are lithologically unlike and of different ages and therefore do not constitute a cross-fault tie that can be used to estimate rightlateral displacement along the San Andreas Fault.In the Maricopa area northeast of the San Andreas Fault, the Bitterwater Creek Shale overlies conglomeratic fan-delta deposits of the upper Miocene Santa Margarita Formation, which in turn overlie siliceous shale of the Miocene Monterey Formation from which we obtained a diatom assemblage dated at about 10.0–9.3 Ma. Previous investigations noted that the Santa Margarita Formation in the Maricopa area contains granitic and metamorphic clasts derived from sources in the northern Gabilan Range, on the opposite side of

  4. The strata and palaeo-geomorphology framework at the end of neoproterozoic and development mode of source rocks at the beginning of Cambrian in Tarim Basin, China

    Directory of Open Access Journals (Sweden)

    Xin Yang

    2017-12-01

    Full Text Available Referred to the new recognition from petroleum exploration of the Sinian to Cambrian in South China, it could be considered that the distribution of the early Cambrian source rocks was controlled by the palaeo-geomorphology at the end of Neoproterozoic in the Tarim Basin. Based on the zircon U-Pb dating of pyroclastic rock samples from the clastic rock stratum under the bottom of Cambrian carbonate rocks, the stratigraphic correlation of the Sinian to Cambrian was conducted to build the palaeo-geomorphology framework at the end of Neoproterozoic in Tarim Basin. Lastly, according to the development mode of source rocks at the beginning of Cambrian, the distribution of source rocks was predicted initially through the division of seismic facies. The youngest zircon concordia age of pyroclastic rocks from the bottom of well Tong 1 is 707±8Ma. It was revealed by the strata framework of the Sinian to Cambrian, the palaeo-geomorphology at the end of Neoproterozoic in Tarim Basin was characterized by an uplift highland in Bachu-Tazhong area, the south north high-low, and the west is higher than the east. The distribution of source rocks in the bottom of the Cambrian on the palaeo-platform and slopes was coincident with the Upper Sinian dolomite basically. But the contemporaneous sediment happened to be absent or changed in sedimentary facies on the uplift and its edges. From the seismic facies of the strata under the bottom of Cambrian, it could be concluded that source rocks in the type of the Xishanbraque Group (∈1xs was limited in the Manjiaer Depression, while the source rocks in the type of the Yuertusi Group (∈1y are widely distributed in south of Tabei Uplift, east Awat Depression, and even the Maigt Slope. However, among the west Awat Depression and western Tanguzibasi Depression, and the middle area of the Bachu-Tazhong Uplifts, the contemporaneous source rocks may have changed into sedimentary facies of tidal flat and lagoon, instead of

  5. The Mexican Ridges Fold Belt, Gulf of Mexico: Deformation, Dynamics of Deposition of Growth Strata, and the Delay of Sedimentary Response to Tectonic Forcing

    Science.gov (United States)

    Yarbuh Lugo, U. I.; Contreras, J.

    2014-12-01

    Deformation of the Mexican Ridges fold belt (MRFB), western Gulf of Mexico, initiated in the Late Neogene in response to normal faulting along the Quetzalcoatl Extensional System offshore Veracruz. Previous authors analyzed stacking patterns of growth strata concluding deformation occurred in two stages: the western section of the fold belt developed during the Upper Miocene whereas the eastern part became active during the Lower Pliocene. Here we analyze a regional seismic line to determine whether deformation migrated progressively eastward. In contrast to previous studies we do not use stacking patterns but excess area. This parameter provides direct information of both linear shortening, and superficial mass transport. We construct excess-area plots for each of the folds comprising the MRFB; from them we estimate the shortening and the degradation path of the seafloor deformed by folding. Moreover, by assuming denudation is in steady state, we are able to differentiate sediments derived locally from sediments transported from distant sources. Results show tectonic transport in the MRFB is 11.8 km; shortening of individual folds ranges 3-16%, with an average strain for the entire MRFB of ~10%; structures grew at a mean uplift rate of 0.2 mm/yr. We estimate the constant of mass diffusivity, which controls the rate of degradation, has a mean value of 0.27 m2/yr. This value is characteristic of rapid, episodic mass movements. Finally, the sedimentation rate is ~0.2 mm/yr. Those parameters, however, are not constant; they decrease toward the deepwater portion of the fold belt. The structures proximal to the continental shelf are rising rapidly and are being degraded more intensely than those in the distal part of the fold belt. Our results reveal that deformation started synchronously throughout the MRFB during the Late Miocene and not in two episodes as previously reported. The reason for the seeming discrepancy is due to the copious sedimentation in the eastern

  6. Bryophyte flora in upland forests at different successional stages and in the various strata of host trees in northeastern Pará, Brazil

    Directory of Open Access Journals (Sweden)

    Ana Cláudia Caldeira Tavares-Martins

    2014-03-01

    Full Text Available In the northeastern region of the Brazilian state of Pará, approximately 90% of the forested areas are secondary forests. Secondary forests are interesting areas for floristic studies aimed at determining the effects that clear-cutting has on bryophyte communities. The aim of this study was to compare upland forests at different successional stages and the various strata of host trees, in terms of the bryophyte species composition. Bryophyte specimens were collected between August 2005 and September 2006 from host trees in primary and secondary forests of different ages and of different heights, within the municipality of Capitão Poço, in the state of Pará. The vertical distribution of bryophytes was evaluated in 15 host trees within the primary forest. We identified a total of 99 bryophyte species: 33 mosses and 66 liverworts. The dominant family was Lejeuneaceae, with 56 species. Most of the species (n = 60 had a neotropical distribution, and 3 species were endemic to Brazil. Cololejeunea minutissima var. myriocarpa (Nees & Mont. R.M.Schust., Pycnolejeunea papillosa X.-L. He, Radula mammosa Spruce and Verdoornianthus marsupiifolius (Spruce Gradst. represent new records for the state of Pará. In the successional forests evaluated, we identified 78 species, most of which (n = 38 occurred in primary forest. On the host tree trunks evaluated in the primary forest, we observed 31 species occurring at heights ranging from 2 m to 20 m. Despite the fact that secondary forests account for such a large proportion of the forested areas in Capitão Poço, we found that the bryoflora was relatively rich, comprising 31% of the species recorded for the state. The fact that 40% of the species recorded occurred exclusively in the secondary forests and the fact that 45.5% of the species recorded in primary forest occurred within the 2-20 m height range show the importance of studies focusing on bryophytes in secondary forests and in the upper strata of

  7. Prediction of Cardiovascular Disease by the Framingham-REGICOR Equation in the High-Risk PREDIMED Cohort: Impact of the Mediterranean Diet Across Different Risk Strata.

    Science.gov (United States)

    Amor, Antonio J; Serra-Mir, Mercè; Martínez-González, Miguel A; Corella, Dolores; Salas-Salvadó, Jordi; Fitó, Montserrat; Estruch, Ramón; Serra-Majem, Lluis; Arós, Fernando; Babio, Nancy; Ros, Emilio; Ortega, Emilio

    2017-03-13

    The usefulness of cardiovascular disease (CVD) predictive equations in different populations is debatable. We assessed the efficacy of the Framingham-REGICOR scale, validated for the Spanish population, to identify future CVD in participants, who were predefined as being at high-risk in the PREvención con DIeta MEDiterránea (PREDIMED) study-a nutrition-intervention primary prevention trial-and the impact of adherence to the Mediterranean diet on CVD across risk categories. In a post hoc analysis, we assessed the CVD predictive value of baseline estimated risk in 5966 PREDIMED participants (aged 55-74 years, 57% women; 48% with type 2 diabetes mellitus). Major CVD events, the primary PREDIMED end point, were an aggregate of myocardial infarction, stroke, and cardiovascular death. Multivariate-adjusted Cox regression was used to calculate hazard ratios for major CVD events and effect modification from the Mediterranean diet intervention across risk strata (low, moderate, high, very high). The Framingham-REGICOR classification of PREDIMED participants was 25.1% low risk, 44.5% moderate risk, and 30.4% high or very high risk. During 6-year follow-up, 188 major CVD events occurred. Hazard ratios for major CVD events increased in parallel with estimated risk (2.68, 4.24, and 6.60 for moderate, high, and very high risk), particularly in men (7.60, 13.16, and 15.85, respectively, versus 2.16, 2.28, and 3.51, respectively, in women). Yet among those with low or moderate risk, 32.2% and 74.3% of major CVD events occurred in men and women, respectively. Mediterranean diet adherence was associated with CVD risk reduction regardless of risk strata ( P >0.4 for interaction). Incident CVD increased in parallel with estimated risk in the PREDIMED cohort, but most events occurred in non-high-risk categories, particularly in women. Until predictive tools are improved, promotion of the Mediterranean diet might be useful to reduce CVD independent of baseline risk. URL: http

  8. Temporal constraints on the tectonic evolution of Sierra De Famatina, northwestern Argentina, using the fission-track method to date tuffs interbedded in synorogenic clastic sedimentary strata

    Energy Technology Data Exchange (ETDEWEB)

    Tabbutt, K.D. (Dartmouth College, Hanover, NH (USA))

    1990-07-01

    Fission-track dates from seven volcaniclastic units allow time constraints to be placed on synorogenic clastic strata exposed along the flanks of Sierra de Famatina, northwest Argentina. Four formations are exposed along the western margin of Sierra de Famatina. The El Abra conglomerate is composed of clasts eroded from the basement exposed just to the west of Cadena de Paiman. The El Buey Formation contains sediments probably derived from the Precordillera fold and thrust belt to the west. Fission-track dates give a maximum age of 6 Ma for the deposition of both of these formations. The El Durazno Formation, deposited between 6 and 4 Ma, contains proximal volcaniclastic and other clastic rocks derived from the core of Sierra de Famatina. The Santa Florentina conglomerate was derived from the rising Sierra de Famatina and deposited in the past 4 m.y. Sierra de Famatima probably became a positive topographic feature approximately 6 Ma. Prior to that time this region was receiving fine-grained sediments from a distal fold and thrust belt and conglomerates from local basement uplifts. Minor extrusive events (Mogote Formation) coincide both spatially and temporally with deformation along the major reverse faults that control the uplift of Sierra de Famatina. Minimum mean uplift rates calculated for Sierra de Famatina are 0.8 {plus minus} 0.1 mm/yr over a 6.8 m.y. interval.

  9. Strata-bound copper-iron sulfide mineralization in a Proterozoic front arc setting at Boksputs, Northwest Cape, South Africa — a possible Besshi-type deposit

    Science.gov (United States)

    Geringer, G. J.; Pretorius, J. J.; Cilliers, F. H.

    1987-04-01

    A low-grade, copper-iron sulfide deposit is present at Boksputs in the Northwest Cape, South Africa. It occurs in the Proterozoic amphibolite belt, the Areachap Group, along the eastern margin of the Namaqua mobile belt. The mineralization, which is dominated by pyrite, chalcocopyrite, sphalerite, and magnetite, occurs as disseminated ore and thin layers of massive-type ore in the lower massive amphibiolite and associated amphibole gneisses of the Kraalkop antiform and synform. Chemically, the host-rock amphibolite resembles low-K arc tholeiite and calc-alkaline volcanics, whereas the upper amphibolite is calc-alkaline. The sulfide mineralization and the host-rock composition is explained in terms of modern plate tectonic principles. It is concluded that the Boksputs mineralization is a syngenetic, strata-bound, copper-iron deposit which to some extend resembles Besshi-type deposits. It is associated with low-K arc tholeiite which is tectonically related to a front arc environment or a rifted arc system along the eastern margin of the Namaqua mobile belt.

  10. Health Surveys Using Mobile Phones in Developing Countries: Automated Active Strata Monitoring and Other Statistical Considerations for Improving Precision and Reducing Biases.

    Science.gov (United States)

    Labrique, Alain; Blynn, Emily; Ahmed, Saifuddin; Gibson, Dustin; Pariyo, George; Hyder, Adnan A

    2017-05-05

    In low- and middle-income countries (LMICs), historically, household surveys have been carried out by face-to-face interviews to collect survey data related to risk factors for noncommunicable diseases. The proliferation of mobile phone ownership and the access it provides in these countries offers a new opportunity to remotely conduct surveys with increased efficiency and reduced cost. However, the near-ubiquitous ownership of phones, high population mobility, and low cost require a re-examination of statistical recommendations for mobile phone surveys (MPS), especially when surveys are automated. As with landline surveys, random digit dialing remains the most appropriate approach to develop an ideal survey-sampling frame. Once the survey is complete, poststratification weights are generally applied to reduce estimate bias and to adjust for selectivity due to mobile ownership. Since weights increase design effects and reduce sampling efficiency, we introduce the concept of automated active strata monitoring to improve representativeness of the sample distribution to that of the source population. Although some statistical challenges remain, MPS represent a promising emerging means for population-level data collection in LMICs. ©Alain Labrique, Emily Blynn, Saifuddin Ahmed, Dustin Gibson, George Pariyo, Adnan A Hyder. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 05.05.2017.

  11. Risk strata-based therapy and outcome in stage Ib-IIa carcinoma cervix: single-centre ten-year experience.

    Science.gov (United States)

    Kundargi, Rajshekar S; Guruprasad, B; Rathod, Praveen Shankar; Shakuntala, Pn; Shobha, K; Pallavi, Vr; Uma Devi, K; Bafna, Ud

    2013-01-01

    To review the outcome of stage (Ib, IIa), cervical cancer patients were primarily treated with radical hysterectomy and risk-based postoperative therapy. Between January 2001 and December 2011, 601 cases underwent surgery followed by tailored therapy. Patients were classified into low risk (pelvic lymph node negative, tumour less than 4 cm, no evidence of lympho-vascular invasion, less than one-third of thickness of surgical stoma involved), intermediate risk (positive lympho-vascular space invasion, tumour size more than 4 cm, and deep invasion of cervical stroma), and high risk (pelvic lymph node involved, positive parametrial, or vaginal margins) groups. Postoperative adju-vant therapy in the form of radiotherapy alone to those with intermediate risk and chemo-radiotherapy to those with high risk was given to patients. The median follow-up was 60 months. The majority of patients had intermediate risk. The overall event-free survival (EFS) at five years was 74.37%, with EFS of 86.5% in those from the low-risk group, 73% in those from the intermediate-risk group, and 64% in those from the high-risk group. In conclusion, risk strata-based adjuvant postoperative therapy is able to provide a favourable outcome in patients with stage Ib-IIa cervical cancer with a nearly 11% improvement in survival compared with historical control.

  12. Distal Limits and Composition of a Late Ordovician (Mohawkian) Biotite-Bearing Volcanic ash, Foreland Carbonate Platform (Verulam Formation), Ottawa Embayment: Helping to Define Magmatic Change in Volcanism Following Later Platform Foundering

    Science.gov (United States)

    Al-Delami, M.; Dix, G. R.

    2009-05-01

    Two thin (~3 cm) biotite-bearing clay beds that are separated by a 1-cm thick crinoidal-brachiopod floatstone can be traced in two cores through the Upper Ordovician Verulam Formation (Ottawa Group) along a 25-km transect in the western portion of the Ottawa Embayment, eastern Ontario. Only a further 3 km to the northwest, neither the beds nor related mineralogy are recognized in either core or outcrop,. The beds contain abraded fragments (5-10 %) of partially chlorite- and illite-altered biotite that floats within a soft, friable clay-mineral matrix of kaolinite, illite, chlorite, and minor smectite. Accessory mineralogy includes phenocrystic apatite, feldspar (orthoclase and albite), amphibole, and magnetite. In the lower bed, biotite grains decrease in both abundance (influence from volcanic input. The Verulam altered ash deposits represent the distal margin of a double volcanic eruption, the source mostly likely within the developing Taconic volcanic arc that once lay along the Late Ordovician foreland basin of eastern Laurentia. Geochemical proxies (Zr/TiO2 and Nb/Y) identify a trachyandesitic to rhyodacitic parent magma. Chlorite alteration may indicate minimum burial temperatures of 130oC, in keeping with burial temperature estimates according to conodont alteration indices (CAI = 3) for the host carbonate platform succession. The MgO and FeO % of biotites from these beds plot within the same field as the slightly older Millbrig and Deike bentonites that also represent ash deposition within shallow-water carbonate platform environments from widespread Late Ordovician eruptions that occurred along the foreland basin margin. Collectively, these compositions are higher in FeO and lower in MgO % values compared those associated with a bentonite within the overlying Taconic foreland shale succession of the Ottawa Embayment, and bentonites in Lower Silurian successions of western Europe. This contrast strengthens a previous hypothesis (Sharma et al., 2005) that

  13. Occurence of a uraniferous-vanadiniferous graphitic phyllite in the Koeli Nappes of the Stekenjokk area, central Swedish Caledonides

    International Nuclear Information System (INIS)

    Sundblad, K.; Gee, D.G.

    1985-01-01

    The Cambro-Ordovician alum shales in Scandinavia have anomalously high contents of certain trace elements, among them U, V and Mo, when compared to other black shales in the world. Variations in the contents of these elements within the formation show a clear correlation with the stratigraphy. Investigation of the content of U, V, and Mo in graphitic phyllites of the Stikke Nappe in the Seve-Koeli Nappe Complex of the Stekenjokk area has identified the presence of anomalously high contents of these elements compared to average black shales. The content of these elements in the graphitic phyllites correlates clearly with that found in the Early Ordovician Dictyonema-bearing shales in eastern Troendelag and on the Baltoscandian Platform; it is, therefore, suggested that these metasediments in Stekenjokk are of the same age. (Author)

  14. Radium mobility and the age of groundwater in public-drinking-water supplies from the Cambrian-Ordovician aquifer system, north-central USA

    Science.gov (United States)

    Stackelberg, Paul E.; Szabo, Zoltan; Jurgens, Bryant C.

    2018-01-01

    High radium (Ra) concentrations in potable portions of the Cambrian-Ordovician (C-O) aquifer system were investigated using water-quality data and environmental tracers (3H, 3Hetrit, SF6, 14C and 4Herad) of groundwater age from 80 public-supply wells (PSWs). Groundwater ages were estimated by calibration of tracers to lumped parameter models and ranged from modern (1 Myr) in the most downgradient, confined portions of the potable system. More than 80 and 40 percent of mean groundwater ages were older than 1000 and 50,000 yr, respectively. Anoxic, Fe-reducing conditions and increased mineralization develop with time in the aquifer system and mobilize Ra into solution resulting in the frequent occurrence of combined Ra (Rac = 226Ra + 228Ra) at concentrations exceeding the USEPA MCL of 185 mBq/L (5 pCi/L). The distribution of the three Ra isotopes comprising total Ra (Rat = 224Ra + 226Ra + 228Ra) differed across the aquifer system. The concentrations of 224Ra and 228Ra were strongly correlated and comprised a larger proportion of the Rat concentration in samples from the regionally unconfined area, where arkosic sandstones provide an enhanced source for progeny from the 232Th decay series. 226Ra comprised a larger proportion of the Ratconcentration in samples from downgradient confined regions. Concentrations of Rat were significantly greater in samples from the regionally confined area of the aquifer system because of the increase in 226Ra concentrations there as compared to the regionally unconfined area. 226Ra distribution coefficients decreased substantially with anoxic conditions and increasing ionic strength of groundwater (mineralization), indicating that Ra is mobilized to solution from solid phases of the aquifer as adsorption capacity is diminished. The amount of 226Ra released from solid phases by alpha-recoil mechanisms and retained in solution increases relative to the amount of Ra sequestered by adsorption processes or co

  15. Geochronology, stratigraphy and geochemistry of Cambro-Ordovician, Silurian and Devonian volcanic rocks of the Saxothuringian Zone in NE Bavaria (Germany)—new constraints for Gondwana break up and ocean-island magmatism

    Science.gov (United States)

    Höhn, Stefan; Koglin, Nikola; Klopf, Lisa; Schüssler, Ulrich; Tragelehn, Harald; Frimmel, Hartwig E.; Zeh, Armin; Brätz, Helene

    2018-01-01

    Stratigraphically well-defined volcanic rocks in Palaeozoic volcano-sedimentary units of the Frankenwald area (Saxothuringian Zone, Variscan Orogen) were sampled for geochemical characterisation and U-Pb zircon dating. The oldest rock suite comprises quartz keratophyre, brecciated keratophyre, quartz keratophyre tuff and basalt, formed in Upper Cambrian to Tremadocian time (c. 497-478 Ma). Basaltic volcanism continued until the Silurian. Quartz keratophyre shows post-collisional calc-alkaline signature, the Ordovician-Silurian basalt has alkaline signature typical of continental rift environments. The combined datasets provide evidence of Cambro-Ordovician bimodal volcanism and successive rifting until the Silurian. This evolution very likely resulted from break-up of the northern Gondwana margin, as recorded in many terranes throughout Europe. The position at the northern Gondwana margin is supported by detrital zircon grains in some tuffs, with typical Gondwana-derived age spectra mostly recording ages of 550-750 Ma and minor age populations of 950-1100 and 1700-2700 Ma. The absence of N-MORB basalt in the Frankenwald area points to a retarded break-off of the Saxothuringian terrane along a continental rift system from Uppermost Cambrian to Middle Silurian time. Geochemical data for a second suite of Upper Devonian basalt provide evidence of emplacement in a hot spot-related ocean-island setting south of the Rheic Ocean. Our results also require partial revision of the lithostratigraphy of the Frankenwald area. The basal volcanic unit of the Randschiefer Formation yielded a Tremadocian age and, therefore, should be attributed to the Vogtendorf Formation. Keratophyre of the Vogtendorf Formation, previously assigned to the Tremadoc, is most likely of Upper Devonian age.

  16. A Resource Assessment Of Geothermal Energy Resources For Converting Deep Gas Wells In Carbonate Strata Into Geothermal Extraction Wells: A Permian Basin Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Erdlac, Richard J., Jr.

    2006-10-12

    Previously conducted preliminary investigations within the deep Delaware and Val Verde sub-basins of the Permian Basin complex documented bottom hole temperatures from oil and gas wells that reach the 120-180C temperature range, and occasionally beyond. With large abundances of subsurface brine water, and known porosity and permeability, the deep carbonate strata of the region possess a good potential for future geothermal power development. This work was designed as a 3-year project to investigate a new, undeveloped geographic region for establishing geothermal energy production focused on electric power generation. Identifying optimum geologic and geographic sites for converting depleted deep gas wells and fields within a carbonate environment into geothermal energy extraction wells was part of the project goals. The importance of this work was to affect the three factors limiting the expansion of geothermal development: distribution, field size and accompanying resource availability, and cost. Historically, power production from geothermal energy has been relegated to shallow heat plumes near active volcanic or geyser activity, or in areas where volcanic rocks still retain heat from their formation. Thus geothermal development is spatially variable and site specific. Additionally, existing geothermal fields are only a few 10’s of square km in size, controlled by the extent of the heat plume and the availability of water for heat movement. This plume radiates heat both vertically as well as laterally into the enclosing country rock. Heat withdrawal at too rapid a rate eventually results in a decrease in electrical power generation as the thermal energy is “mined”. The depletion rate of subsurface heat directly controls the lifetime of geothermal energy production. Finally, the cost of developing deep (greater than 4 km) reservoirs of geothermal energy is perceived as being too costly to justify corporate investment. Thus further development opportunities

  17. Correlation and stratigraphic eruption age of the pyroclastic flow deposits and wide spread volcanic ashes intercalated in the Pliocene-Pleistocene strata, central Japan

    International Nuclear Information System (INIS)

    Nagahashi, Yoshitaka; Satoguchi, Yasufumi; Yoshikawa, Shusaku

    2000-01-01

    Three pyroclastic flow deposits in the Takayama and Omine area, central Honshu, are correlated to the distal widespread volcanic ashes intercalated in the Plio-Pleistocene boundary strata in central Japan. The correlation is based on these stratigraphic relationships, facies, magnetostratigraphy, petrographic properties such as mineral assemblage, refractive index and chemical composition of the volcanic glasses and orthopyroxene. As the result of these correlation, the eruption age of the proximal pyroclastic flow deposits have become clear. And precise correlation between proximal eruption units and distal depositional units is now possible. Ho-Kd 39 Tephra erupted at about 1.76 Ma, forming a co-ignimbrite ash, which deposited in the Kanto sedimentary basin. Eb-Fukuda Tephra erupted at about 1.75 Ma, and distal volcaniclastic deposit sedimented in the Kinki, Niigata and Kanto sedimentary basins. The eruptional and depositional phase are divided into the stage 1, stage 2 (early), stage 2 (late) and stage 3. Stage 1 is phreato-plinian type eruption phase, forming distal ash fall deposit. Stage 2 (early) is plinian pumice fall, intra-plinian pyroclastic flow and plinian pumice fall eruption phase, forming distal ash fall. Stage 2 (late) is final eruptional phase of the biggest pyroclastic flow of the Eb-Fukuda Tephra, forming a co-ignimbrite ash fall. Stage 3 is resedimented stage after the end of the explosive eruption. It is notable that resedimented volcaniclastic deposit reached Osaka sedimentary basin 300 km away from the eruption center. Om-SK110 Tephra erupted at about 1.65 Ma, divided into the stage 1, stage 2 and stage 3. Stage 1 is eruption phase of the plinian pumice fall and first pyroclastic flow. Stage 2 is pauses in eruption activity. Stage 3 is second pyroclastic flow phase, it is inferred that the pyroclastic flow of the stage 3 directly entered the Niigata sedimentary basin and simultaneously formed a co-ignimbrite ash. (author)

  18. The relationship between adiposity-associated inflammation and coronary artery and abdominal aortic calcium differs by strata of central adiposity: The Multi-Ethnic Study of Atherosclerosis (MESA).

    Science.gov (United States)

    Hughes-Austin, Jan M; Wassel, Christina L; Jiménez, Jessica; Criqui, Michael H; Ix, Joachim H; Rasmussen-Torvik, Laura J; Budoff, Matthew J; Jenny, Nancy S; Allison, Matthew A

    2014-08-01

    Adipokines regulate metabolic processes linked to coronary artery (CAC) and abdominal aorta calcification (AAC). Because adipokine and other adiposity-associated inflammatory marker (AAIM) secretions differ between visceral and subcutaneous adipose tissue, we hypothesized that central adiposity modifies associations between AAIMs and CAC and AAC. We evaluated 1878 MESA participants with complete measures of AAIMs, anthropometry, CAC, and AAC. Associations of AAIMs with CAC and AAC prevalence and severity were analyzed per standard deviation of predictors (SD) using log binomial and linear regression models. The waist-to-hip ratio (WHR) was dichotomized at median WHR values based on sex/ethnicity. CAC and AAC prevalence were defined as any calcium (Agatston score >0). Severity was defined as ln (Agatston score). Analyses examined interactions with WHR and were adjusted for traditional cardiovascular disease risk factors. Each SD higher interleukin-6 (IL-6), fibrinogen and CRP was associated with 5% higher CAC prevalence; and each SD higher IL-6 and fibrinogen was associated with 4% higher AAC prevalence. Associations of IL-6 and fibrinogen with CAC severity, but not CAC prevalence, were significantly different among WHR strata. Median-and-above WHR: each SD higher IL-6 was associated with 24.8% higher CAC severity. Below-median WHR: no association (p interaction =0.012). Median-and-above WHR: each SD higher fibrinogen was associated with 19.6% higher CAC severity. Below-median WHR: no association (p interaction =0.034). Adiponectin, leptin, resistin, and tumor necrosis factor-alpha were not associated with CAC or AAC prevalence or severity. These results support findings that adiposity-associated inflammation is associated with arterial calcification, and further add that central adiposity may modify this association. © The Author(s) 2014.

  19. Information and communication technology demands at work: the association with job strain, effort-reward imbalance and self-rated health in different socio-economic strata.

    Science.gov (United States)

    Stadin, Magdalena; Nordin, Maria; Broström, Anders; Magnusson Hanson, Linda L; Westerlund, Hugo; Fransson, Eleonor I

    2016-10-01

    The use of information and communication technology (ICT) is common in modern working life. ICT demands may give rise to experience of work-related stress. Knowledge about ICT demands in relation to other types of work-related stress and to self-rated health is limited. Consequently, the aim of this study was to examine the association between ICT demands and two types of work-related stress [job strain and effort-reward imbalance (ERI)] and to evaluate the association between these work-related stress measures and self-rated health, in general and in different SES strata. This study is based on cross-sectional data from the Swedish Longitudinal Occupational Survey of Health collected in 2014, from 14,873 gainfully employed people. ICT demands, job strain, ERI and self-rated health were analysed as the main measures. Sex, age, SES, lifestyle factors and BMI were used as covariates. ICT demands correlated significantly with the dimensions of the job strain and ERI models, especially with the demands (r = 0.42; p < 0.01) and effort (r = 0.51; p < 0.01) dimensions. ICT demands were associated with suboptimal self-rated health, also after adjustment for age, sex, SES, lifestyle and BMI (OR 1.49 [95 % CI 1.36-1.63]), but job strain (OR 1.93 [95 % CI 1.74-2.14) and ERI (OR 2.15 [95 % CI 1.95-2.35]) showed somewhat stronger associations with suboptimal self-rated health. ICT demands are common among people with intermediate and high SES and associated with job strain, ERI and suboptimal self-rated health. ICT demands should thus be acknowledged as a potential stressor of work-related stress in modern working life.

  20. Epigenetic dolomitization of the Přaídolí formation (Upper Silurian), the Barrandian basin, Czech Republic: implications for burial history of Lower Paleozoic strata

    Science.gov (United States)

    Suchý, V.; Rozkošný, I.; Žák, K.; Franců, J.

    1996-06-01

    approximately 3-km-thick sedimentary overburden of presumably post-Givetian strata, no longer preserved in the basin, appears to be the most likely interpretation. This interpretaion may imply that the magnitude of post-Variscan erosion in the Barrandian area was substantially greater than previously thought.

  1. Epigenetic dolomitization of the Přídolí formation (Upper Silurian), the Barrandian basin, Czech Republic: implications for burial history of Lower Paleozoic strata

    Science.gov (United States)

    Suchý, V.; Rozkošný, I.; Žák, K.; Franců, J.

    -km-thick sedimentary overburden of presumably post-Givetian strata, no longer preserved in the basin, appears to be the most likely interpretation. This interpretaion may imply that the magnitude of post-Variscan erosion in the Barrandian area was substantially greater than previously thought.

  2. Investigation on the upper Paleozoic Strata in Tang-e-Zakeen, and introducing Zakeen formation, Kuh-e Faraghan Zagros Basin, South Iran

    International Nuclear Information System (INIS)

    Ghavidel-Syooki, M.

    1998-01-01

    A thick clastic sequence is well-developed in Tang-e-Zakeen, Kuh-e-Faraghan, being situated approximately 80 Km north of Bandar Abbas. The sequence is 340 m. thick and mainly consists of sandstone, siltstone, shale and subordinate dolomitic beds. So far, this clastic sequence has been called Faraghan Formation. This rock unit lacks marine fauna and based on stratigraphic position, it was assigned to the Early Permian (Szabo and Kheradpir, 1978). Since then, a detailed palynological study has been carried out on the Faraghan Formation by the author. These studies resulted identification of numerous palynomorph taxa, including miospore and acritarch species. The known palynomorph taxa indicated that, a major part of Faraghan Formation belongs to the Devonian Period, while the rest is Early Permian. As a result, the National Iranian Stratigraphic Committee decided and agreed upon to divide the Faraghan Formation into two rock units, namely, the Zakeen Formation, embracing the Devonian strata, and Faraghan Formation for the Early Permian sequence in the Zagros Basin respectively. The Zakeen Formation derives from the Zakeen Village which is located in the southern flank of Kuh-e-Faraghan, about 80 km north of Bandar Abbas. The type section of Zakeen Formation attains a thickness of 285m. in Tang-e-Zakeen, Kuh-e-Faraghan, approximately 23 Km from the Zakeen village. It disconformably rests on the Sarchahan Formation, while it too, disconformably overlain by the Faraghan Formation. A total of 100 samples from the Zakeen Formation were selected and treated in the palynological laboratory of the Exploration Division of National Iranian Oil Company. 63 palynomorph taxa were encountered from the Zakeen Formation. The known species were arranged in five local stratigraphic assemblage zones. Zones I and II occur in a thickness of 96 m. of the Zakeen Formation, in ascending order, suggesting the Early Devonian whereas Zones III and IV occur Within 156 m. interval of the Zakeen

  3. Free convective controls on sequestration of salts into low-permeability strata: Insights from sand tank laboratory experiments and numerical modelling

    Science.gov (United States)

    Simmons, C. T.; Post, V.

    2008-12-01

    Vertical reflux of dense brines may occur in hydrogeologic situations including seawater intrusion, transgression-regression cycles, leachate migration from landfills and brine reflux beneath salt lakes. The critical control that geologic heterogeneity plays in the free convective process is still an area which requires significant exploration. To date, no studies have been published that focus on the effect that discrete low- permeability structures have on the free convection process at the scale of individual lenses. The precise local scale solute transport mechanisms that affect solute exchange between the layers of lower and higher permeability have not been reported. Using sand tank experiments and numerical models, we explore local scale solute transport processes associated with free convection in the region both surrounding and within discrete low-permeability strata. Different permeability geometries and contrasts between high- and low- permeability regions are explored. Results show that the free convective processes are inherently complex and not intuitively obvious. In the high-permeability region, salinization was rapid and occurred predominantly by free convective flow around the low-permeability blocks, a process we refer to as 'interlayer convection'. Fresh water originally present within the overall domain considered became trapped both below and within the low-permeability structures. A free convection flow field also became concurrently established within the low-permeability lenses, a process we refer to as 'intralayer convection'. This smaller sublayer scale process is driven by both larger scale interlayer convection and by the buoyancy of the fresh water within the low permeability lenses. It was found that upward vertical flow retards salinization of the lenses as these buoyant freshwater displacements oppose the downward penetration of dissolved salts by diffusion and free convection from above. Due to the presence of vertical upward flow

  4. RELASI BAHASA ARAB DENGAN STRATA SOSIAL MASYARAKAT DAN IMPLIKASINYA TERHADAP KEHIDUPAN SOSIAL, EKONOMI, POLITIK DAN AGAMA (Kajian Sosiolinguistik Pada Masyarakat Tutur Arab Keturunan di Kelurahan Kauman Pekalongan Timur

    Directory of Open Access Journals (Sweden)

    Muhandis *

    2014-03-01

    Full Text Available This study is categorized as sociolinguistic studies and used language variation theory based on social ranks -- they are: Akrolek, Basilek, Vulgar, Kolokial -- and interactional theory which is a process of interaction that build, maintain, and change certain habits in language and symbols. Listening, speaking, and Noting were used to collect data. unified and apportion analysis method were used to analyze data. The results were: (1 the existence of social rank within the Arab community in Kauman descent was: (a Cleric group. They were entitled Al-Jufri, Al- Hadad, Al-Ethiopia, Yahya, Shihab, Bawazier and so forth; (b Masayikh group. They were fam Bafadhal, Bahomaid, Baraja, Baharmi (Baharmus, Bawazir, Basyu'aibn, Bamozaham, Ba'abad, bin Khatib, Bin Zabdah, Basalamah; and (c Ghabili group. Those who holds Bashir, Baswedan, Sungkar, Abud, Alkatiri, Badjubier, Bafadhal, and so forth. The existence of regional variations of low and high diversity of languages based on social strata, for example قهار Gahar (angry, حريم Harim (wife, Sir سر (the streets is a slang vocabulary that includes a low range of languages. If they were categorized in the high language using word غضبان, قرينة , and .أمشى The mention of the word pilgrims for Arabs descent, call ahlul wathan for the Javanese and Chinese descent Baodeh for socially showed no difference in social status between the Javanese and Arab descent on one side, and The Chinese descent on the other side. Regional variations of low and high diversity of languages based on their economic status, usually rich people are often invoked as 'Royyes' ( ريس which has the meaning of the aristocracy, including the diversity of languages is low while the high diversity of languages is صاحب الجلالة . Low variation in the range of political language is the word Haromi ( حرمى which is Arabic kolokial have meaning 'thief' or 'Corruptor' high variety of Arabic word 'Corruptor

  5. Birth and demise of the Rheic Ocean magmatic arc(s): Combined U-Pb and Hf isotope analyses in detrital zircon from SW Iberia siliciclastic strata

    Science.gov (United States)

    Pereira, M. F.; Gutíerrez-Alonso, G.; Murphy, J. B.; Drost, K.; Gama, C.; Silva, J. B.

    2017-05-01

    Frasnian sedimentation occurred through the opening of a back-arc basin formed along the Laurussian active margin during Rheic Ocean subduction, as has been recently proposed for the Rhenohercynian Zone in Central Europe. Detrital zircon ages in the Frasnian siliciclastic rocks indicate provenance in the Meguma terrane, Avalonia and Devonian Rheic Ocean arc(s). As a result of back-arc basin inversion, the Frasnian formations underwent deformation, metamorphism and denudation and were unconformably overlain by Famennian to Visean siliciclastic strata (including the Phyllite-Quartzite Formation of the South Portuguese Zone). The Latest Devonian-Early Carboniferous detritus were probably shed to the Pulo do Lobo Zone (Represa and Santa Iria formations) by recycling of Devonian siliciclastic rocks, from the South Portuguese Zone (Meguma terrane) and from a new distinct source with Baltica/Laurentia derivation (preserved in the Horta da Torre Formation and Alajar Mélange).

  6. Subsidence by liquefaction-fluidization in man-made strata around Tokyo bay, Japan: from geological survey on damaged part at the 2011 off the Pacific Coast of Tohoku Earthquake

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    O. Kazaoka

    2015-11-01

    Full Text Available Geological disaster by liquefaction-fluidization happened on southern part of the Quaternary Paleo-Kanto submarine basin at the 2011 Earthquake off the Pacific Coast of Tohoku. Liquefaction-fluidization phenomena occurred mainly in man-made strata over shaking 5+ intensity of Japan Meteorological Agency scale. Many subsided spots, 10–50 m width, 20–100 m length and less than 1 m depth, by liquefaction-fluidization distributed on reclaimed land around northern Tokyo bay. Large amount of sand and groundwater spouted out in the terrible subsided parts. But there are little subsidence and no jetted sand outside the terrible subsided part. Liquefaction-fluidization damaged part at the 1987 earthquake east off Chiba prefecture re-liquefied and fluidized in these parts at the 2011 great earthquake. The damaged area were more wide on the 2011 earthquake than the 1987 quake. Detailed classification maps of subsidence by liquefaction-fluidization on the 2011 grate earthquake were made by fieldwork in Chiba city around Tokyo bay. A mechanism of subsidence by liquefaction-fluidization in man-made strata was solved by geological survey with continuous large box cores on the ACE Liner and large relief peals of the cores at a typical subsided part.

  7. Subsidence by liquefaction-fluidization in man-made strata around Tokyo bay, Japan: from geological survey on damaged part at the 2011 off the Pacific Coast of Tohoku Earthquake

    Science.gov (United States)

    Kazaoka, O.; Kameyama, S.; Shigeno, K.; Suzuki, Y.; Morisaki, M.; Kagawa, A.; Yoshida, T.; Kimura, M.; Sakai, Y.; Ogura, T.; Kusuda, T.; Furuno, K.

    2015-11-01

    Geological disaster by liquefaction-fluidization happened on southern part of the Quaternary Paleo-Kanto submarine basin at the 2011 Earthquake off the Pacific Coast of Tohoku. Liquefaction-fluidization phenomena occurred mainly in man-made strata over shaking 5+ intensity of Japan Meteorological Agency scale. Many subsided spots, 10-50 m width, 20-100 m length and less than 1 m depth, by liquefaction-fluidization distributed on reclaimed land around northern Tokyo bay. Large amount of sand and groundwater spouted out in the terrible subsided parts. But there are little subsidence and no jetted sand outside the terrible subsided part. Liquefaction-fluidization damaged part at the 1987 earthquake east off Chiba prefecture re-liquefied and fluidized in these parts at the 2011 great earthquake. The damaged area were more wide on the 2011 earthquake than the 1987 quake. Detailed classification maps of subsidence by liquefaction-fluidization on the 2011 grate earthquake were made by fieldwork in Chiba city around Tokyo bay. A mechanism of subsidence by liquefaction-fluidization in man-made strata was solved by geological survey with continuous large box cores on the ACE Liner and large relief peals of the cores at a typical subsided part.

  8. Characteristics of type III kerogen in coal-bearing strata from the Pennsylvanian (Upper Carboniferous) in the Ruhr Basin, Western Germany: Comparison of coals, dispersed organic matter, kerogen concentrates and coal-mineral mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Jasper, K. [Institute of Geology and Geochemistry of Petroleum and Coal, Lochnerstr. 4-20, RWTH Aachen University, 52056 Aachen (Germany); Institute of Geology and Palaeontology, RWTH Aachen University, 52056 Aachen (Germany); Krooss, B.M.; Littke, R. [Institute of Geology and Geochemistry of Petroleum and Coal, Lochnerstr. 4-20, RWTH Aachen University, 52056 Aachen (Germany); Flajs, G. [Institute of Geology and Palaeontology, RWTH Aachen University, 52056 Aachen (Germany); Hartkopf-Froeder, C. [Geological Survey North Rhine-Westphalia, De-Greiff-Str. 195, 47803 Krefeld (Germany)

    2009-10-01

    Quality, quantity and maturity of coal and dispersed terrigenous organic matter were studied on six coal-bearing intervals in Duckmantian strata (Pennsylvanian/Upper Carboniferous) of the Ruhr Basin, Western Germany. Between 10 and 40 samples were collected from fresh drill cores of each interval typically consisting of a coal seam as well as clastic roof and floor strata (sandstone, siltstone, claystone). Coal seams constitute about 8 vol.% of the succession studied. The samples were analysed by organic petrological methods and Rock-Eval pyrolysis. Maturity expressed in terms of vitrinite reflectance is between 0.75 and 1.0 %. For the six successions studied, the total amount of dispersed organic matter in clastic rocks is about half of that stored in coal seams, both containing predominantly vitrinite. Significant differences between Rock-Eval parameters determined on whole rock samples and kerogen concentrates were observed, especially with respect to Hydrogen Index (HI) values. Thus, the HI of the coal is about twice as high as that of the dispersed organic matter, although the maceral composition is similar. The effects of minerals were further examined by Rock-Eval pyrolysis of artificial mixtures of coal (lignite) powder and different minerals. Reduced HI values are partly explained by the retention of generated hydrocarbons on mineral surfaces and partly by reactions of generated fluids with pyrite in kerogen concentrates. (author)

  9. Overview of the influence of syn-sedimentary tectonics and palaeo-fluvial systems on coal seam and sand body characteristics in the Westphalian C strata, Campine Basin, Belgium

    Science.gov (United States)

    Dreesen, Roland; Bossiroy, Dominique; Dusar, Michiel; Flores, R.M.; Verkaeren, Paul; Whateley, M. K. G.; Spears, D.A.

    1995-01-01

    The Westphalian C strata found in the northeastern part of the former Belgian coal district (Campine Basin), which is part of an extensive northwest European paralic coal basin, are considered. The thickness and lateral continuity of the Westphalian C coal seams vary considerably stratigraphically and areally. Sedimentological facies analysis of borehole cores indicates that the deposition of Westphalian C coal-bearing strata was controlled by fluvial depositional systems whose architectures were ruled by local subsidence rates. The local subsidence rates may be related to major faults, which were intermittently reactivated during deposition. Lateral changes in coal seam groups are also reflected by marked variations of their seismic signatures. Westphalian C fluvial depositional systems include moderate to low sinuosity braided and anastomosed river systems. Stable tectonic conditions on upthrown, fault-bounded platforms favoured deposition by braided rivers and the associated development of relatively thick, laterally continuous coal seams in raised mires. In contrast, rapidly subsiding downthrown fault blocks favoured aggradation, probably by anastomosed rivers and the development of relatively thin, highly discontinuous coal seams in topogenous mires.

  10. Strata-bound Fe-Co-Cu-Au-Bi-Y-REE deposits of the Idaho Cobalt Belt: Multistage hydrothermal mineralization in a magmatic-related iron oxide copper-gold system

    Science.gov (United States)

    Slack, John F.

    2012-01-01

    Mineralogical and geochemical studies of strata-bound Fe-Co-Cu-Au-Bi-Y-rare-earth element (REE) deposits of the Idaho cobalt belt in east-central Idaho provide evidence of multistage epigenetic mineralization by magmatic-hydrothermal processes in an iron oxide copper-gold (IOCG) system. Deposits of the Idaho cobalt belt comprise three types: (1) strata-bound sulfide lenses in the Blackbird district, which are cobaltite and, less commonly, chalcopyrite rich with locally abundant gold, native bismuth, bismuthinite, xenotime, allanite, monazite, and the Be-rich silicate gadolinite-(Y), with sparse uraninite, stannite, and Bi tellurides, in a gangue of quartz, chlorite, biotite, muscovite, garnet, tourmaline, chloritoid, and/or siderite, with locally abundant fluorapatite or magnetite; (2) discordant tourmalinized breccias in the Blackbird district that in places have concentrations of cobaltite, chalcopyrite, gold, and xenotime; and (3) strata-bound magnetite-rich lenses in the Iron Creek area, which contain cobaltiferous pyrite and locally sparse chalcopyrite or xenotime. Most sulfide-rich deposits in the Blackbird district are enclosed by strata-bound lenses composed mainly of Cl-rich Fe biotite; some deposits have quartz-rich envelopes.Whole-rock analyses of 48 Co- and/or Cu-rich samples show high concentrations of Au (up to 26.8 ppm), Bi (up to 9.16 wt %), Y (up to 0.83 wt %), ∑REEs (up to 2.56 wt %), Ni (up to 6,780 ppm), and Be (up to 1,180 ppm), with locally elevated U (up to 124 ppm) and Sn (up to 133 ppm); Zn and Pb contents are uniformly low (≤821 and ≤61 ppm, respectively). Varimax factor analysis of bulk compositions of these samples reveals geochemically distinct element groupings that reflect statistical associations of monazite, allanite, and xenotime; biotite and gold; detrital minerals; chalcopyrite and sparse stannite; quartz; and cobaltite with sparse selenides and tellurides. Significantly, Cu is statistically separate from Co and As

  11. Enhanced provenance interpretation using combined U-Pb and (U-Th)/He double dating of detrital zircon grains from lower Miocene strata, proximal Gulf of Mexico Basin, North America

    Science.gov (United States)

    Xu, Jie; Stockli, Daniel F.; Snedden, John W.

    2017-10-01

    Detrital zircon U-Pb analysis is an effective approach for investigating sediment provenance by relating crystallization age to potential crystalline source terranes. Studies of large passive margin basins, such as the Gulf of Mexico Basin, that have received sediment from multiple terranes with non-unique crystallization ages or sedimentary strata, benefit from additional constraints to better elucidate provenance interpretation. In this study, U-Pb and (U-Th)/He double dating analyses on single zircons from the lower Miocene sandstones in the northern Gulf of Mexico Basin reveal a detailed history of sediment source evolution. U-Pb age data indicate that most zircon originated from five major crystalline provinces, including the Western Cordillera Arc (Pan-African (700-500 Ma) and Canadian Shield (>1800 Ma) terranes. Zircon (U-Th)/He ages record tectonic cooling and exhumation in the U.S. since the Mesoproterozoic related to the Grenville to Laramide Orogenies. The combined crystallization and cooling information from single zircon double dating can differentiate volcanic and plutonic zircons. Importantly, the U-Pb-He double dating approach allows for the differentiation between multiple possible crystallization-age sources on the basis of their subsequent tectonic evolution. In particular, for Grenville zircons that are present in all of lower Miocene samples, four distinct zircon U-Pb-He age combinations are recognizable that can be traced back to four different possible sources. The integrated U-Pb and (U-Th)/He data eliminate some ambiguities and improves the provenance interpretation for the lower Miocene strata in the northern Gulf of Mexico Basin and illustrate the applicability of this approach for other large-scale basins to reconstruct sediment provenance and dispersal patterns.

  12. PHYTOSOCIOLOGY OF THE ARBOREAL AND NATURAL REGENERATION STRATA IN A BLACK-WATTLE (Acacia mearnsii De Wild. PLANTATION IN THE REGION OF SEMIDECIDUIS SEASONAL FORESTS OF RIO GRANDE DO SUL

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    Silas Mochiutti

    2009-10-01

    Full Text Available This study analyzes the structure and floristic composition of the regeneration of native forest species under black-wattle plantation, established 16 years ago in a riparian area, and it verifies the possibility of the black-wattle be considered an invasive species of this environment. The tree stratum (circumference at breast height (CBH ≥15 cm was evaluated in 12 plots of 100 m2, established in four blocks. The natural regeneration stratum (0.3 m height to <15 cm CBH was evaluated in two subplots of 9 m2, established in opposite vertexes of each plot. The tree stratum was composed by 26 species of 14 families and the natural regeneration stratum by 49 species of 23 families. The Shannon diversity index for species, considering all plots, was 2.60 and 3.06 to the tree and natural regeneration strata, respectively. The native species, Casearia sylvestris, Myrsine lorentziana and Zanthoxylum petiolare presented the larger importance value in the tree stratum and Faramea marginata, Myrsine lorentziana and Myrcia glabra the biggest density in the natural regeneration stratum. The ecological characteristics of the species found in several height strata indicated that the forest succession process is in evolution. The black-wattle did not regenerate in this area and the planted trees of this species are in the senescence phase. Only 100 tree/ha of black-wattle were found, which represents 4.5% of the original population. Thus, black-wattle is not an invasive species for this environment.

  13. 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

  14. 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

  15. Geochemistry, zircon U-Pb ages and Sr-Nd-Hf isotopes of an Ordovician appinitic pluton in the East Kunlun orogen: New evidence for Proto-Tethyan subduction

    Science.gov (United States)

    Xiong, Fuhao; Ma, Changqian; Wu, Liang; Jiang, Hong'an; Liu, Bin

    2015-11-01

    , magnetite and titanite has driven the appinitic magma to cogenetic granodiorite. The Late Ordovician mafic appinites indicate that there did exist Proto-Tethyan subduction along the South Kunlun suture zone, and the subduction would add significant volumes of sediment-derived melts into the depleted mantle wedge, resulting into metasomatism and melting with the formation of appinitic magma.

  16. Permeability to brine of crushed salt rock for waste isolation, considering long-term pressure variation of overlying strata and dissolution processes. Final report; Durchlaessigkeitsverhalten von Steinsalzversatz gegenueber Laugen unter Beruecksichtigung von zeitlich veraenderlichen Ueberlagerungsdruecken und Loesungsvorgaengen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Froehlich, H. [Battelle Ingenieurtechnik GmbH, Eschborn (Germany); Conen, O. [Technische Univ. Darmstadt (Germany); Haefner, F.; Bruck, J. v. der [Technische Univ. Bergakademie Freiberg (Germany)

    1999-07-01

    It cannot be excluded that there will be ingress of brines to underground isolation plants for nuclear and chemical toxic wastes. The transport mechanisms in the waste repository are much determined by the perviousness of the backfilling and the sealing material used after waste emplacement in salt rock mine shafts. The critical quantity is the permeability, both for inflow of brine into the bedded waste areas, and for contaminated brine squeeze-out mechanisms. The project research work was to establish the mass transfer parameters for calculating the transport mechanisms in backfilled and sealed shafts. Using near-reality simulation of conditions, the time-dependent influence of pressure variations of overlying strata, humidity and salt/brine interactions on the permeability was examined and quantified. (orig./CB) [German] In Endlagern fuer nukleare und chemotoxische Abfaelle im Salinar kann der Zutritt von Laugen nicht prinzipiell ausgeschlossen werden. Die Transportvorgaenge innerhalb des Endlagers werden wesentlich von der Durchlaessigkeit der Versatzmaterialien und der Verschluesse bestimmt. Die bestimmende Groesse, sowohl fuer den Laugenzufluss in die Einlagerungsbereiche als auch fuer das Auspressen kontaminierter Lauge aus dem Endlager, ist dabei die Permeabilitaet. Ziel der hier vorgestellten Arbeiten war es, Stofftransportparameter fuer die Berechnung von Ausbreitungsvorgaengen in den verfuellten Bereichen eines salinaren Endlagers bereitzustellen. Unter Simulation realitaetsnaher Bedingungen wurde der Einfluss von zeitabhaengigem Ueberlagerungsdruck (Gebirgsdruck), Feuchte und die Wechselwirkung von Salz/Lauge auf das Durchlaessigkeitsverhalten untersucht und quantifiziert. (orig.)

  17. Seasonal variation in the number of captures of Artibeus lituratus (Olfers, 1818 and Sturnira lilium (E. Geoffroy, 1810 (Chiroptera: Phyllostomidae in the upper strata of an Atlantic Forest remnant in southern Brazil

    Directory of Open Access Journals (Sweden)

    Fernando Carvalho

    2014-09-01

    Full Text Available This study aimed to analyze the occurrence of seasonal variations in the number of captures of Artibeus lituratus and Sturnira lilium in the upper strata of an Atlantic Forest remnant in southern Brazil. It was conducted in the town of Pedras Grandes, in the southern end of Santa Catarina. The chiropterans were captured with mist nets installed in the canopy and subcanopy. To check whether there were differences in the number of captures between seasons, we used the chi-square test (χ2, with a significance level of 0.05, and, whenever needed, partial χ2 tests. Artibeus lituratus showed significant differences between seasons, and the largest number of captures occurs in autumn. For S. lilium we did not observe statistically significant differences. The seasonal variation found out for A. lituratus may be related to its diet, which is based on fruits whose availability has seasonal variations. For S. lilium, besides the diet, mainly based on plants that do not have seasonal variations with regard to fruit availability, the altitude of the study area and its variations in temperature also seem to explain the absence of seasonal variation.

  18. A new type of Nb (Ta)-Zr(Hf)-REE-Ga polymetallic deposit in the late Permian coal-bearing strata, eastern Yunnan, southwestern China: Possible economic significance and genetic implications

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Shifeng; Wang, Xibo; Luo, Yangbing; Song, Zhentao; Ren, Deyi [State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083 (China); Zhou, Yiping; Zhang, Mingquan; Wang, Jumin; Song, Xiaolin; Yang, Zong [Yunnan Institute of Coal Geology Prospection, Kunming 650218 (China); Jiang, Yaofa [Xuzhou Institute of Architectural Technology, Xuzhou 221116 (China)

    2010-07-01

    This paper describes a new type of Nb(Ta)-Zr(Hf)-REE-Ga polymetallic deposit of volcanic origin in the late Permian coal-bearing strata of eastern Yunnan, southwestern China. Well logging data (especially natural gamma-ray), geochemical data (high concentrations of Nb, Ta, Zr, Hf, REE, and Ga) and mineralogical compositions (Nb(Ta)-, Zr(Hf)-, or REE-bearing minerals rarely observed), together with the volcanic lithological characteristics indicate that there are thick (1-10 m, mostly 2-5 m) ore beds in the lower Xuanwei Formation (late Permian) in eastern Yunann of southwestern China. The ore beds are highly enriched in (Nb,Ta){sub 2}O{sub 5} (302-627 ppm), (Zr,Hf)O{sub 2} (3805-8468 ppm), REE (oxides of La-Lu + Y) (1216-1358 ppm), and Ga (52.4-81.3 ppm). The ore beds are mainly composed of quartz, mixed-layer illite-smectite, kaolinite, berthierine, and albite. Four types of ore beds in the study area were identified, namely, clay altered volcanic ash, tuffaceous clay, tuff, and volcanic breccia. Preliminary studies suggest that the high concentrations of otherwise rare metals were mainly derived from the alkalic pyroclastic rocks. The modes of occurrence, spatial distribution, and enrichment mechanism of the rare metals, however, require further study. (author)

  19. Understanding complex structures in fold-and-thrust belts. Integration of geometric and growth strata analyses, paleomagnetism, AMS and analogue models in the Western termination of the Southern Pyrenees

    Science.gov (United States)

    Pueyo, Emilio L.; Sánchez, Elisa; Oliva-Urcia, Belén; José Ramón, Ma

    2014-05-01

    Classic 2D approaches have helped the understanding of the geometry and kinematics of fold-and-thrust belts belts (FAT belts) but are insufficient to unravel many natural cases. This is because deformation is 3D from the geometric point of view and, thus, cylindrical features may be considered as a simplification. On the other hand, deformation kinematics is usually complex, diachronic and poliphasic in real cases. Therefore, FAT belts have to be always considered in 4D. In this sense, the Southern Pyrenees is a perfect location to study the evolution of FAT belts because of the exceptional outcropping conditions of growth strata, the proven diachronic kinematics and the non-coaxial interference of deformation events. Within the vast catalogue of complex structures that includes superposed folding, conical and plunging folds, oblique thrust ramps, etc here, we have selected the westernmost termination of the South Pyrenean sole thrust to illustrate how the integration of geometric and kinematic analysis can help unraveling complex structures in FAT belts. The San Marzal pericline (4 km2 surface extension) is the lateral termination of the Sto. Domingo deca-kilometric fold. San Marzal looks like a large 70° plunging cylindrical structure. However the large magnitude (≡ 60-70°) of vertical axis rotations accommodated between its flanks cannot be explained without a conical geometry. In this work we will show how the structural analysis performed on this structure has disentangled its complex geometry. This analyses comprises several hundreds of bedding data, joints and veins and more than 150 standard paleomagnetic and AMS sites. Besides, we will show how the kinematic information derived from magnetostratigraphic sections (more than 8 km of sampled profiles) has helped to constraint the folding and rotation ages and velocities. Finally, all these complex geometric and kinematic features have inspired us to build an analogue model where we can explore the 3D

  20. El estrato socioeconómico como factor predictor del uso constante de condón en adolescentes Socioeconomic strata as a predictor factor for consistent condom use among adolescents

    Directory of Open Access Journals (Sweden)

    Ramiro Caballero Hoyos

    2001-12-01

    Full Text Available OBJETIVO: El estrato socioeconómico juega un rol importante en las desigualdades en salud. En México, la prevalencia más alta de casos de SIDA se encuentra en población de estratos más bajos. El propósito de lo estudio fue describir el estrato socioeconómico (ajustado por variables psicosociales, situacionales y demográficas como un factor predictor del uso consistente del condón, en adolescentes. MÉTODOS: Se incluyó en el estudio una muestra de una encuesta previa aplicada a 1.410 adolescentes de 15 a 19 años y estratificada por edad, género y estrato socioeconómico de Guadalajara, México. El análisis fue aplicado sobre los 251 adolescentes que reportaron actividad sexual. El análisis estadístico se realizó mediante Ji Cuadrada, t-test, ANOVA y regresión logística. RESULTADOS: La frecuencia de uso consistente de condón fue 30,7% y hubo una prevalencia de uso irregular. El estrato socioeconómico alto fue el principal predictor (OR= 11,1, CI95%= 2,6-47,6. Otros predictores significativos fueron el género masculino, el soporte de los pares y el nivel alto de conocimientos sobre VIH/SIDA. CONCLUSIÓN: El estrato socioeconómico es un importante factor predictor del uso consistente del condón.INTRODUCTION: Socioeconomic level plays an important role in health inequalities. In Mexico, the highest prevalence of AIDS cases is among individuals of lower socioeconomic level. The purpose of the study was to describe the socioeconomic level (adjusted for psychosocial, situational and demographic variables as a predictor factor for the consistent condom use among adolescents of Guadalajara, Mexico. METHODS: A sample of 1,410 adolescents, aged 15 to 19 years, drawn from a previous survey stratified by age, gender and socioeconomic strata was included in the study. Analysis was performed in 251 adolescents who reported sexual activity. Statistical analysis was performed using Chi-square, t-test, ANOVA, and logistic regression. RESULTS

  1. Geology and sequence stratigraphy of undiscovered oil and gas resources in conventional and continuous petroleum systems in the Upper Cretaceous Eagle Ford Group and related strata, U.S. Gulf Coast Region

    Science.gov (United States)

    Dubiel, Russell F.; Pearson, Ofori N.; Pitman, Janet K.; Pearson, Krystal M.; Kinney, Scott A.

    2012-01-01

    The U.S. Geological Survey (USGS) recently assessed the technically recoverable undiscovered oil and gas onshore and in State waters of the Gulf Coast region of the United States. The USGS defined three assessment units (AUs) with potential undiscovered conventional and continuous oil and gas resources in Upper Cretaceous (Cenomanian to Turonian) strata of the Eagle Ford Group and correlative rocks. The assessment is based on geologic elements of a total petroleum system, including hydrocarbon source rocks (source rock maturation, hydrocarbon generation and migration), reservoir rocks (sequence stratigraphy and petrophysical properties), and traps (formation, timing, and seals). Conventional oil and gas undiscovered resources are in updip sandstone reservoirs in the Upper Cretaceous Tuscaloosa and Woodbine Formations (or Groups) in Louisiana and Texas, respectively, whereas continuous oil and continuous gas undiscovered resources reside in the middip and downdip Upper Cretaceous Eagle Ford Shale in Texas and the Tuscaloosa marine shale in Louisiana. Conventional resources in the Tuscaloosa and Woodbine are included in the Eagle Ford Updip Sandstone Oil and Gas AU, in an area where the Eagle Ford Shale and Tuscaloosa marine shale display vitrinite reflectance (Ro) values less than 0.6%. The continuous Eagle Ford Shale Oil AU lies generally south of the conventional AU, is primarily updip of the Lower Cretaceous shelf edge, and is defined by thermal maturity values within shales of the Eagle Ford and Tuscaloosa that range from 0.6 to 1.2% Ro. Similarly, the Eagle Ford Shale Gas AU is defined downdip of the shelf edge where source rocks have Ro values greater than 1.2%. For undiscovered oil and gas resources, the USGS assessed means of: 1) 141 million barrels of oil (MMBO), 502 billion cubic feet of natural gas (BCFG), and 4 million barrels of natural gas liquids (MMBNGL) in the Eagle Ford Updip Sandstone Oil and Gas AU; 2) 853 MMBO, 1707 BCFG, and 34 MMBNGL in the

  2. Differential incremental value of ultrasound carotid intima-media thickness, carotid plaque, and cardiac calcium to predict angiographic coronary artery disease across Framingham risk score strata in the APRES multicentre study.

    Science.gov (United States)

    Gaibazzi, Nicola; Rigo, Fausto; Facchetti, Rita; Carerj, Scipione; Giannattasio, Cristina; Moreo, Antonella; Mureddu, Gian Francesco; Salvetti, Massimo; Grolla, Elisabetta; Faden, Giacomo; Cesana, Francesca; Faggiano, Pompilio

    2016-09-01

    According to recent data, more accurate selection of patients undergoing coronary angiography for suspected coronary artery disease (CAD) is needed. From the Active PREvention Study multicentre prospective study, we further analyse whether carotid intima-media thickness (cIMT), carotid plaques (cPL), and echocardiographic cardiac calcium score (eCS) have incremental discriminatory and reclassification predictive value for CAD over clinical risk score in subjects undergoing coronary angiography, specifically depending on their low, intermediate, or high class of clinical risk. In eight centres, 445 subjects without history of prior CAD but with chest pain of recent onset and/or a positive/inconclusive stress test for ischaemia prospectively underwent clinically indicated elective coronary angiography after cardiac and carotid ultrasound assessments with measurements of cIMT, cPL, and eCS. The study population was divided into subjects at low (10%), intermediate (10-20%), and high (>20%) Framingham risk score (FRS). Ultrasound parameters were tested for their incremental value to predict CAD over FRS, in each pre-test risk category. No significant difference could be appreciated between the discrimination value of FRS and Diagnostic Imaging for Coronary Artery Disease score for the presence of CAD. eCS or cPL demonstrated significant incremental prediction over FRS, consistently in the three FRS categories (P risk subjects, in whom cPL was apparently not incremental over FRS, and eCS was only of borderline significance for better discrimination. Ultrasound eCS and cPL assessments were significant predictors of angiographic CAD in patients without prior CAD but with signs or symptoms suspect for CAD, independently and incrementally to FRS, across all pre-test risk probability strata, although in high-risk subjects, only eCS maintained an incremental value. The use of cIMT was not significantly incrementally useful in any FRS risk category. Published on behalf of the

  3. Comportamentos de risco para transtornos do comportamento alimentar entre adolescentes do sexo feminino de diferentes estratos sociais do Nordeste do Brasil Risk behaviors for eating disorders among female adolescents from different social strata in the Brazilian Northeastern

    Directory of Open Access Journals (Sweden)

    Antonio Maia Olsen do Vale

    2011-01-01

    Full Text Available Este estudo procurou estimar a prevalência de transtornos do comportamento alimentar (TCA e identificar fatores de risco entre adolescentes do sexo feminino em Fortaleza (Ceará, Brasil. Realizou-se um estudo seccional com 652 estudantes secundaristas (14-20 anos usando-se o Teste de Investigação Bulímica de Edimburgo (BITE. Aplicou-se um modelo de regressão logística. Cerca de um quarto das participantes apresentou padrão alimentar de risco e práticas de controle de peso; em 1,2% encontraram-se indícios de TCA instalado. Medo de engordar foi relatado por 62%, independentemente de estudarem em colégios públicos ou particulares (p>0,05, mas uso de práticas de risco foi superior naquelas procedentes de escolas particulares (pThis study sought to estimate the prevalence of eating disorders (ED and identify risk factors among female adolescents in Fortaleza, Ceará, Brazil. It was conducted a sectional study with 652 high school students (14-20 years using the Bulimic Investigatory Test of Edinburgh (BITE. A logistic regression model was applied. Approximately one quarter of participants showed risk eating pattern and control weight practices, among 1.2% signs of an installed ED were found. Fear of weight gain was reported by 62% of adolescents, independently if studying at public or private schools (p>0.05, but the use of risk practices was higher among private schools students (p<0.05. Not having a religion (OR: 2.2, 95%CI: 1.1-4.2 and studying in private school (OR: 1.7, 95%CI: 1.2-2.5 were associated with an increased risk of ED. The ED emerge as a public health problem even in the poor areas of Brazil and the desire for a thin body was not differentiated between different social strata, although the risk practices are significantly higher among respondents from private schools. Subjective and cultural aspects are presented not only as risk factors, but also as protectors.

  4. Comparison of Michigan Basin crude oils

    Science.gov (United States)

    Vogler, E. A.; Meyers, P. A.; Moore, W. A.

    1981-01-01

    Michigan Basin oils from the Ordovician Trenton, Silurian Niagaran, and Devonian Dundee formations have been geochemically compared by GC, GC-MS, and carbon isotope mass spectrometry. One oil from each formation was selected for detailed analysis which included measurement of individual n-alkane delta 13 C values. The Ordovician and Devonian oils are strikingly similar to one another, yet clearly different from the Silurian oil. This pattern is unexpected because Ordovician and Devonian reservoirs are physically separated by the Silurian strata. From time-temperature considerations, the Devonian oil probably was formed in older strata and has migrated to its present location. Our analyses suggest a common source for the Devonian and Ordovician oils.

  5. Comparison of Michigan Basin crude oils

    Science.gov (United States)

    Vogler, Erwin A.; Meyers, Philip A.; Moore, Wayne A.

    1981-11-01

    Michigan Basin oils from the Ordovician Trenton, Silurian Niagaran, and Devonian Dundee formations have been geochemically compared by GC, GC-MS, and carbon isotope mass spectrometry. One oil from each formation was selected for detailed analysis which included measurement of individual n-alkane δ13C values. The Ordovician and Devonian oils are strikingly similar to one another, yet clearly different from the Silurian oil. This pattern is unexpected because Ordovician and Devonian reservoirs are physically separated by the Silurian strata. From time-temperature considerations, the Devonian oil probably was formed in older strata and has migrated to its present location. Our analyses suggest a common source for the Devonian and Ordovician oils.

  6. Incipiently drowned platform deposit in cyclic Ordovician shelf sequence: Lower Ordovician Chepultepec Formation, Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Bova, J.A.; Read, J.F.

    1983-03-01

    The Chepultepec interval, 145 to 260 m (476 to 853 ft) thick, in Virginia contains the Lower Member up to 150 m (492 ft) thick, and the Upper Member, up to 85 m (279 ft) thick, of peritidal cyclic limestone and dolomite, and a Middle Member, up to 110 m (360 ft) thick, of subtidal limestone and bioherms, passing northwestward into cyclic facies. Calculated long term subsidence rates were 4 to 5 cm/1000 yr (mature passive margin rates), shelf gradients were 6 cm/km, and average duration of cycles was 140,00 years. Peritidal cyclic sequences are upward shallowing sequences of pellet-skeletal limestone, thrombolites, rippled calcisiltites and intraclast grainstone, and laminite caps. They formed by rapid transgression with apparent submergence increments averaging approximately 2 m (6.5 ft) in Lower Member and 3.5 m (11.4 ft), Upper Member. Deposition during Middle Member time was dominated by skeletal limestone-mudstone, calcisiltite with storm generated fining-upward sequences, and burrow-mixed units that were formed near fair-weather wave base, along with thrombolite bioherms. Locally, there are upward shallowing sequences, of basal wackestone/mudstone to calcisiltite to bioherm complexes (locally with erosional scalloped tops). Following each submergence, carbonate sedimentation was able to build to sea level prior to renewed submergence. Large submergence events caused tidal flats to be shifted far to the west, and they were unable to prograde out onto the open shelf because of insufficient time before subsidence was renewed, and because the open shelf setting inhibited tidal flat deposition. The Middle Member represents an incipiently drowned sequence that developed by repeated submergence events.

  7. Paleozoic unconformities favorable for uranium concentration in northern Appalachian basin

    International Nuclear Information System (INIS)

    Dennison, J.M.

    1986-01-01

    Unconformities can redistribute uranium from protore rock as ground water moves through poorly consolidated strata beneath the erosion surface, or later moves along the unconformity. Groundwater could migrate farther than in present-day lithified Paleozoic strata in the Appalachian basin, now locally deformed by the Taconic and Allegheny orogenies. Several paleoaquifer systems could have developed uranium geochemical cells. Sandstone mineralogy, occurrences of fluvial strata, and reduzate facies are important factors. Other possibilities include silcrete developed during desert exposure, and uranium concentrated in paleokarst. Thirteen unconformities are evaluated to determine favorable areas for uranium concentration. Cambrian Potsdam sandstone (New York) contains arkoses and possible silcretes just above crystalline basement. Unconformities involving beveled sandstones and possible fluvial strata include Cambrian Hardyston sandstone (New Jersey), Cambrian Potsdam Sandstone (New York), Ordovician Oswego and Juniata formations (Pennsylvania and New York), Silurian Medina Group (New York), and Silurian Vernon, High Falls, and Longwood formations (New York and New Jersey). Devonian Catskill Formation is beveled by Pennsylvanian strata (New York and Pennsylvania). The pre-Pennsylvanian unconformity also bevels Lower Mississippian Pocono, Knapp, and Waverly strata (Pennsylvania, New York, and Ohio), truncates Upper Mississippian Mauch Chunk Formation (Pennsylvania), and forms paleokarst on Mississippian Loyalhanna Limestone (Pennsylvania) and Maxville Limestone (Ohio). Strata associated with these unconformities contain several reports of uranium. Unconformities unfavorable for uranium concentration occur beneath the Middle Ordovician (New York), Middle Devonian (Ohio and New York), and Upper Devonian (Ohio and New York); these involve marine strata overlying marine strata and probably much submarine erosion

  8. The lower Darriwilian (Middle Ordovician) at the northern extreme of the Mendoza Precordillera, Argentina: stratigraphic and biostratigraphic implications; El Darriwiliense inferior (Ordovícico Medio) en el extremo norte de la Precordillera de Mendoza, Argentina: implicaciones estratigráficas y bioestratigráficas

    Energy Technology Data Exchange (ETDEWEB)

    Beresi, M.S.; Bordonaro, O.L.; Heredia, S.E.; Mestre, A.; Toro, B.A.

    2017-09-01

    A tectonically affected Middle Ordovician succession crops out at the Los Guanacos quarry in the sierra de Las Higueras, in the Precordillera of Mendoza, western Argentina. This is represented by the San Juan Formation which is transitionally covered by a mixed carbonate-shaly unit of dark colours, 1.5 metres thick (transfacies) which can be interpreted as the base of the Los Azules Formation. A 5-cm thick intra-bioclastic pack/grainstone bed interbedded in the lower part of this unit has been interpreted as a tempestite. It is characterized both by a millimetre-thick erosional boundary, just above the dark mudstone layer and strong mechanical distribution of bioclasts and intraclasts, suggesting sedimentary structures associated with a storm event of high energy possibly occurring in the middle part of the platform. Towards the bottom, a hummocky structure thin interval, under the dark mudstone, is interpreted as the record of another tempestite event. The mudstone represents the post-storm event reflecting the low energy of the marine water environment. The lenticular layer contains predominantly lingulid shells, trilobites and graptolites, all highly fragmented, which suggests they have been reworked and subsequently mixed and quickly redeposited during a storm event that caused the mortality of these faunas. The trilobites Mendolaspis salagastensis and indeterminate species of Matagnostidae, Illaenidae, Leiostegiidae, Encrinuridae, Telephinidae and Trinucleidae have been recorded for the first time at this locality. The conodont fauna allows the identification of the Yangtzeplacognathus crassus Zone, which indicates the lower Darriwilian (Middle Ordovician). Graptolites assignable to evisograptus cf. Levisograptus austrodentatus and Levisograptus sp. are described for the first time in the studied area and biostratigraphic implications validate the early Darriwilian age for the bearing levels. Finally, based on the studied records, correlation with different

  9. Overview of the potential and identified petroleum source rocks of the Appalachian basin, eastern United States: Chapter G.13 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    Science.gov (United States)

    Coleman, James L.; Ryder, Robert T.; Milici, Robert C.; Brown, Stephen; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    The Appalachian basin is the oldest and longest producing commercially viable petroleum-producing basin in the United States. Source rocks for reservoirs within the basin are located throughout the entire stratigraphic succession and extend geographically over much of the foreland basin and fold-and-thrust belt that make up the Appalachian basin. Major source rock intervals occur in Ordovician, Devonian, and Pennsylvanian strata with minor source rock intervals present in Cambrian, Silurian, and Mississippian strata.

  10. High-resolution seismic studies on geothermal heat extraction from low, permeable rock strata in the city of Hanover using depth-dependent, optimized acquisition parameters; Hochaufloesende seismische Untersuchungen zur Erdwaermegewinnung aus tiefen, permeablen Gesteinsformationen im Stadtgebiet Hannover unter Verwendung von Profilen mit teufenabhaengig optimierten Akquisitionsparametern

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R. [GGA-Inst. fuer Geowissenschaftliche Gemeinschaftsaufgaben, Hannover (Germany)

    2002-07-01

    The investigations accompanied a demonstration project on geothermal heat production planned by GEOZENTRUM, Hanover, in which geothermal heat will be produced from muschelkalk and mottled sandstone in the area of Hanover/Misburg by means of ''generated geothermal systems'' (GeneSys). This involves detailed seismic exploration of the geological strata of all depth levels. Profile data of the Thoense gas field will be integrated. [German] Die Untersuchungen stehen im Zusammenhang mit dem vom GEOZENTRUM-Hannover geplanten Demonstrationsvorhaben zur Erdwaermegewinnung mittels ''Generierter geothermischer Energie Systeme'' (GeneSys) im Stadtgebiet Hannover/Misburg. Zielhorizonte sind der Muschelkalk und der Buntsandstein. Dazu sollten die geologischen Strukturen im gesamten Teufenbereich detailliert seismisch erkundet werden, wobei neben neuen Messungen auch die vorliegenden Informationen aus bereits gemessenen Profilen des Gasfeldes Thoense einfliessen. (orig.)

  11. Carbonate microfacies of the San Juan Formation (Ordovician: Oepikodus evae and Oepikodus intermedius conodont zones), Niquivil, Central Precordillera, Province of San Juan (Argentina); Microfacies carbonáticas de la Formación San Juan (Ordovícico: zonas de conodontos Oepikodus evae y Oepikodus intermedius), Niquivil, Precordillera Central, Provincia de San Juan (Argentina)

    Energy Technology Data Exchange (ETDEWEB)

    Soria, T.; Beresi, M.; Mestre, A.; Heredia, S.; Rodríguez, M.C.

    2017-09-01

    This contribution presents the description and interpretation of carbonate microfacies of the San Juan Formation (Ordovician) at the Niquivil section, considering the stratigraphical interval between the Oepikodus evae and Oepikodus intermedius conodont zones. The distribution of the microfacies and the conodonts assemblages allow us to identify different sub-environments within the late Floian carbonate ramp of the Central Precordillera. Five microfacies were recognized from the base to the top: M1 Bioclastic mudstone-wackestone; M2 Bioclastic-peloidal wackestone; M3 Intra-bioclastic wackestone; M4 Intra-bioclastic packstone; M5 Peloidal grainstone. The vertical distribution of these microfacies indicates a shallowing trend of the carbonate ramp in the Niquivil section for this temporal interval, which suggests a middle ramp environment with low energy, without wave action, and that evolved towards the middle-inner ramp environment with more energy by wave action and development of tempestites. [Spanish] En la presente contribución se realiza la descripción e interpretación de las microfacies carbonáticas de la Formación San Juan (Ordovícico) en la sección de Niquivil, considerando el intervalo estratigráfico comprendido entre las zonas de conodontos Oepikodus evae y Oepikodus intermedius. El análisis de las microfacies y los conodontos asociados permiten el reconocimiento de diferentes subambientes carbonáticos dentro de la rampa carbonática desarrollada durante el Floiense tardío de la Precordillera Central. Se reconocieron cinco microfacies que, de base a techo, son: M1 Mudstone-Wackestone bioclástico; M2 Wackestone bioclástico-peloidal; M3 Wackestone intra-bioclástico; M4 Packstone intra-bioclástico; M5 Grainstone peloidal. La interpretación vertical de estas microfacies indica una tendencia hacia la somerización de la rampa carbonática en la sección de Niquivil para el lapso temporal estudiado. El que se correspondería con un ambiente de

  12. Examination of the Reelfoot Rift Petroleum System, south-central United States, and the elements that remain for potential exploration and development

    Science.gov (United States)

    Coleman, James; Pratt, Thomas L.

    2016-01-01

    The Reelfoot rift is one segment of a late Proterozoic(?) to early Paleozoic intracontinental rift complex in the south-central United States. The rift complex is situated beneath Mesozoic to Cenozoic strata of the Mississippi embayment of southeastern Missouri, northeastern Arkansas, and western Tennessee and Kentucky. The rift portion of the stratigraphic section consists primarily of synrift Cambrian and Ordovician strata, capped by a postrift sag succession of Late Ordovician to Cenozoic age. Potential synrift source rocks have been identified in the Cambrian Elvins Shale. Thermal maturity of Paleozoic strata within the rift ranges from the oil window to the dry gas window. Petroleum generation in Elvins source rocks likely occurred during the middle to late Paleozoic. Upper Cretaceous sedimentary rocks unconformably overlie various Paleozoic units and define the likely upper boundary of the petroleum system.

  13. Low-grade metamorphism of Cambro-Ordovician successions in the Famatina belt, Southern-Central Andes: Burial-inversion history linked to the evolution of the proto-Andean Gondwana margin Metamorfismo de bajo grado de sucesiones cambro-ordovícicas en el cinturón del Famatina, Andes Centrales de Argentina: Historia de enterramiento-exhumación ligada a la evolución del margen proto-andino de Gondwana

    Directory of Open Access Journals (Sweden)

    Gilda Collo

    2011-07-01

    Full Text Available The metamorphic P-T conditions of low-grade units from the Famatina belt, Central Andes of Argentina, were estimated through petrography, X-ray diffraction, and electron microscopy. For the Middle-Upper Cambrian Negro Peinado Formation a tectono-metamorphic event associated with intense intrafoliar folding, with estimated temperatures between 290 and 400°C (KIcis: 0.16-0.27A°29, biotite blastesis and compositional homogeneity in dioctahedral micas and intermediate pressure conditions (white mica b parameter: 9.010Á-9.035Á, was recognized. The Achavil Formation (Middle-Upper Cambrian presents a main metamorphic event associated with temperatures between 200 and 290°C (KIcis: 0.26-0.41A°29 and intermediate- to low-pressure conditions (white mica b parameter values: 8.972Á-9.017Á. Some illitic substitution in dioctahedral micas also indicates lower metamorphic grade than the Negro Peinado Formation. For Upper Cambrian to Middle Ordovician sequences a burial metamorphic pattern, with a progressive decrease in metamorphic grade from Volcancito Formation to Cerro Morado Group (ca. 490-465 Ma; KIcis: 0.31-0.69A°29 and absence of tendency changes linked to strati-graphic discontinuities was proposed. Mica and chlorite are the main phyllosilicates in the oldest units, while Ilt/ Sme (R3 mixed-layer is almost the only one in the youngest. White mica b parameter indicates intermediate- to low-pressure conditions for all these sequences. This burial metamorphic pattern presents a marked break as the youngest Ordovician unit (La Aguadita Formation, after ca. 452 Ma records higher metamorphic conditions (IKcis: 0.28-0.19A°29 than units from the Ordovician arc, with estimated temperatures between 270 and 330°C and intermediate-pressure conditions. Our results indicate that basin contraction and inversion processes related to the Ordovician Ocloyic Orogeny involved at least two well-discriminated and not superposed metamorphic episodes in this region

  14. Relações entre a distribuição das espécies de diferentes estratos e as características do solo de uma floresta aluvial no Estado do Paraná, Brasil Species distribution relationships of different strata and soil characteristics in an alluvial forest in Paraná State, Brazil

    Directory of Open Access Journals (Sweden)

    Joema Carvalho

    2009-03-01

    Full Text Available Entre os fatores que influenciam a distribuição de espécies nas comunidades vegetais localizadas em regiões ribeirinhas, as características do solo são consideradas os mais importantes. No presente estudo, foram avaliadas a composição florística, a diversidade e a estrutura de três estratos da vegetação e suas relações com as características do solo em um fragmento de floresta aluvial na bacia do rio Iguaçu, no estado do Paraná. Buscou-se verificar se a estrutura e a diversidade da floresta nos diferentes estratos podem ser explicadas por fatores edáficos e hídricos. Caracterizaram-se os parâmetros estruturais e a composição florística de três estratos da vegetação % de regeneração (20 cm 1,30 m; 20 sub-parcelas de 5 m×5 m e superior (PAP > 15 cm, 20 parcelas de 10 m×10 m - e correlacionaram-se as abundâncias das espécies com os parâmetros do solo e do lençol freático de cada parcela. A floresta caracterizou-se por baixa diversidade (H' = 2,36 no estrato de regeneração, 2,49 no estrato no estrato intermediário e 1,59 no estrato superior e alta similaridade florística entre estratos (índices de similaridade de Sørensen > 0,65. As relações entre a distribuição espacial das espécies e as características do solo foram distintas entre estratos: no estrato superior correlacionou-se com a profundidade do lençol freático e o teor de matéria orgânica; no intermediário, com profundidade do lençol e teor de alumínio, porém no estrato inferior nenhum dos fatores ambientais analisados explicou a distribuição das espécies. Os resultados sugerem que a estrutura e a composição florística destas comunidades aluviais refletem os diferentes níveis de interação ao longo do ciclo de vida dos indivíduos.Soil characteristics are the most important factors influencing species distribution in alluvial forests. Here we evaluated species composition, diversity and structure of three forest strata and their

  15. Isotopic character of Cambro-Ordovician plutonism, southern Victoria Land

    International Nuclear Information System (INIS)

    Cox, S.C.; Parkinson, D.L.; Allibone, A.H.; Cooper, A.F.

    2000-01-01

    Previous mapping of granitoid rocks in the Dry Valleys area of southern Victoria Land, Antarctica, identified the calc-alkaline (DV1a), adakitic (DV1b), and monzonitic (DV2) suites. A fourth older suite comprising alkaline gabbro, syenite, and A-type granite occurs in the Mt Dromedary area c. 80 km to the south. U-Pb zircon dating of Bonney Pluton, the largest calc-alkaline DV1a intrusion, indicates emplacement of this regional-scale body at 505 +/- 2 Ma. Pb-loss and inherited zircon were common to Bonney Pluton analyses of this study. U-Pb dating of monazite from Valhalla Pluton, a principal DV1b suite adakitic intrusion, indicates emplacement at 488 +/- 2 Ma. The Bonney Pluton age constrains the peak of calc-alkaline plutonism at 505 Ma and the Valhalla Pluton age records the major pulse of adakitic plutonism that is inferred to mark the final stages of subduction c. 490 Ma along this section of the East Antarctic margin. Nd and Sr isotope data for the calc-alkaline DV1a suite and adakitic DV1b suite define distinct ranges for each suite, supporting their subdivision on the basis of field relationships, petrography, and whole-rock geochemistry. Calc-alkaline DV1a suite granite magmas have eNd(T) = -4.2 to -6.1 and Sri = 0.7071-0.7079, whereas the adakitic DV1b suite rocks have a wider range of eNd(T) = -1.9 to -7.2 and Sri = 0.7065-0.7097. The isotopic data suggest a significant mantle component and subordinate crustal component in the source region of both suites. Time-dependent variations in the isotopic ratios of DV1a and DV1b suites imply a progressive increase in the proportion of more radiogenic material in the source region of the granitoid rocks, either mantle- or crust-derived material. Larger adakitic DV1b plutons are more 'evolved' than equivalent, smaller plutons of the same DV1b suite. Vanda Dikes and monzonitic DV2 suite intrusions are characterised by particularly low Sri = 0.7044-0.7067 and near-constant eNd(T) = -4.8 to -5.3, which indicate a petrogenesis for these younger intrusions distinct from the older DV1a and DV1b suites. Gabbroic rocks from Mt Dromedary have eNd(T) values as low as -8.0 and Sri ratios as high as 0.7108, despite their mafic composition, confirming they are unrelated to granitoids in the Dry Valleys area. A granulite xenolith in the McMurdo Volcanics with calc-alkaline DV1a-type chemistry yielded a concordant U-Pb zircon age of 490 +/- 5 Ma. The age suggests that some of the lower crust in southern Victoria Land was emplaced during the Ross Orogeny rather than forming entirely during earlier Precambrian event(s). Isotopic ratios of metasediments and granitoids in the Dry Valleys correlate most closely with rocks that comprise the Beardmore 'Microcontinent' in the Central Transantarctic Mountains, rather than the Nimrod Group and crosscutting intrusions of the Miller Range. The DV1a suite granitoids in the Dry Valleys are petrographically and geochemically similar to calc-alkaline granitoids in northern Victoria Land, but have less-evolved isotopic compositions that imply a lower proportion of crustal material in the source of the southern Victoria Land granitoid rocks. The isotopic data imply complex variations in the chemistry and genesis of granitoid rocks parallel to, as well as perpendicular to, the trend of the Ross Orogen. (author)

  16. Miospore evolution from the Ordovician to the Silurian.

    Science.gov (United States)

    Steemans, P

    2000-12-01

    The definition of the term cryptospore is amended to include only spores thought to be produced by embryophytes and to exclude all enigmatic palynomorphs. Cryptospores are included here in the miospore group.The oldest published assemblage of typical cryptospores is Llanvirn in age. The evolution of cryptospore assemblages is very slow from the Llanvirn to the early Llandovery. The Telychian and Sheinwoodian stages are periods of drastic impoverishment in cryptospore biodiversity, followed by an important modification in miospore assemblages. This step in the evolution of the vegetation is correlated with the rapid transgression of seas on the continent during the early Llandovery. On the other hand, the Hirnantian glaciation does not affect diversity of the miospore assemblages.

  17. Ordovician ash geochemistry and the establishment of land plants

    OpenAIRE

    Parnell John; Foster Sorcha

    2012-01-01

    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 s...

  18. Interrogation of distributional data for the End Ordovician crisis interval

    DEFF Research Database (Denmark)

    Mac Ørum Rasmussen, Christian; Harper, David Alexander Taylor

    2011-01-01

    The uppermost Ordovician–lowermost Silurian (Upper Katian–Rhuddanian) is surveyed with respect to the a- and ß-diversity of rhynchonelliformean brachiopods. The survey is based on new collections as well as existing literature, compiled in a large, georeferenced database. The brachiopod faunas ar...

  19. The Ordovician ostracodes established by Aurel Krause, Part I

    Directory of Open Access Journals (Sweden)

    R. Schallreuter

    2011-02-01

    Full Text Available The lack of a revision of the ostracodes described by Aurel Krause at the end of the 19th century from glacial erratic boulders from Berlin and the Mark Brandenburg (Northern Germany has led to taxonomic confusion in the corresponding literature of the 20th century. To attain stability in names, some of Krause's ostracode species have been revised based on the types stored in the Museum für Naturkunde Berlin, namely Primitia plana, P. plana tuberculata, P. intermedia, P. globifera, Entomis sigma antiquata, Bollia v-scripta, B. granulosa, B. duplex, Strepula lineata, Isochilina canaliculata, Beyrichia dissecta, B. mamillosa, B. signata, and B. bidens. Most species have up to four younger synonyms among species described later from outcrops or borings in Baltoscandia or glacial erratic boulders of Northern Germany and Sweden. Three of Krause's species, which have been considered as nomina dubia by Jaanusson are in fact valid species. Some of Krause's species or of their synonyms are type species. doi:10.1002/mmng.201000015

  20. The Ordovician ostracodes established by Aurel Krause, Part II

    Directory of Open Access Journals (Sweden)

    R. Schallreuter

    2013-08-01

    Full Text Available The revision of ostracodes originally established by Aurel Krause is continued and finished with the description of the following species: Primitia distans, P. elongata, P. cincta, P. excavata, P. papillata, P. plicata, P. schmidtii, Strepula limbata, S. simplex, Entomis obliqua, E. plicata, E. sigma, E. sigma ornata, E. simplex, E. trilobata, Beyrichia erratica, B. erratica granulosa, B. erratica acuta, B. harpa, and B. marchica lata. Three of these species are younger primary homonyms. For Beyrichia erratica granulosa Krause, 1891 a respective decision of the ICZN according to art. 23.9.5 is presently unnecessary, because it has an older synonym (Beyrichia grewingkii Bock, 1867, and Primitia excavata Krause, 1892 has a younger synonym (Laccochilina paucigranosa Jaanusson, 1957. The third homonym, Beyrichia marchica lata Krause, 1891, is considered as a nomen protectum. Entomis sigma ornata, and E. plicata are presently considered as nomina dubia. Since the type material of the three species P. distans, E. sigma, and E. simplex is apparently lost, neotypes are designated. doi:10.1002/mmng.201300007

  1. Fractional extensions of some boundary value problems in oil strata

    Indian Academy of Sciences (India)

    115. [5] Erdélyi A, Magnus W, Oberhettinger F and Tricomi F G, (eds), Higher transcendental functions (New York: McGraw-Hill) (1955) vol. III, ch. 18. [6] Erdélyi A, Magnus W, Oberhettinger F and Tricomi F G, (eds), Tables of integral trans-.

  2. Numerical Modelling Study of Behaviour of Consolidated Strata ...

    African Journals Online (AJOL)

    http://dx.doi.org/10.4314/star.v3i2.25 · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact AJOL · News. OTHER RESOURCES... for Researchers · for Journals · for Authors · for Policy Makers ...

  3. Strata: typed semi-structured data in DokuWiki

    NARCIS (Netherlands)

    Wanders, B.; te Brinke, Steven

    2014-01-01

    A semantic wiki is a wiki that has a model of the knowledge contained in its pages. Currently, semantic wikis are not adopted by a large user base, because most implementations are research prototypes that implement their own wiki engine. To increase familiarity with semantic wikis and quick

  4. Determination of Formation Strata and Groundwater Potential in ...

    African Journals Online (AJOL)

    MICHAEL

    that viable aquifer at Sapele and Jesse is generally within 25m although false and contaminated aquifer may be intercepted at 10 -15 m. On the contrary ... associated contamination. Geophysical investigation is therefore ... battery was used to send current down into the earth through the outer electrodes. A maximum ...

  5. The evolutionary strata of DARPP-32 tail implicates hierarchical ...

    Indian Academy of Sciences (India)

    2014-05-01

    May 1, 2014 ... Some species such as elephant, horse, and rabbit independently lost their PP1 docking motifs yet retain. T34 sites. Microbat has large truncation at N-terminus encompassing many conserved critical residues including T34 and T75, probably due to change of lifestyle that disused DARPP-32. 502. CY Ung ...

  6. Variations in health status within and between socioeconomic strata

    OpenAIRE

    Ferrer, R; Palmer, R

    2004-01-01

    Objectives: To analyse the variability in health status within as well as between socioeconomic groups. What is the range of individual variability in the health effects of socioeconomic status? Is the adverse effect of lower socioeconomic status uniform across the entire distribution of health status?

  7. Palynostratigraphy and age correlation of subsurface strata within ...

    Indian Academy of Sciences (India)

    Journal of Earth System Science. Current Issue : Vol. 126, Issue 8 · Current Issue Volume 126 | Issue 8. December 2017. Home · Volumes & Issues · Special Issues · Forthcoming Articles · Search · Editorial Board · Information for Authors · Subscription ...

  8. Proterozoic strata-bound uranium deposits of Zambia and Zaire

    International Nuclear Information System (INIS)

    Meneghel, L.

    1984-01-01

    The Katanga System, host to uranium and copper mineralisation, is several thousands of metres thick and rests unconformably on an older complex of crystalline rocks and metasediments and is locally covered by Karoo sandstones or Kalahari sands. The deposition of the Katanga System took place during the Late Proterozoic in a wide complex basin extending from Shaba province in Zaire through a large part of Zambia and into eastern Angola. The sediments were affected by different grades of metamorphism, tectonic events, and by thermal events associated with post-tectonic metamorphism. At the base of Katanga system there are 84 known copper deposits and 42 uranium occurrences. It is suggested that all the known uranium and copper occurrences are of an essentially syngenetic sedimentary origin. The mineralisation is found in the Lower Roan Formation near the base of the Katanga System occurring in rocks produced in similar environmental conditions and thus being stratigraphic controlled, however, their areal distribution is localised producing a regional metal zonation. Many of the uranium occurrences have a typical vein aspect. These transgressive relationships are not inconsistent with a syngenetic origin as evidenced by the vein morphology. (author)

  9. The evolutionary strata of DARPP-32 tail implicates hierarchical ...

    Indian Academy of Sciences (India)

    2014-05-01

    May 1, 2014 ... play between kinases and phosphatases. However, a mam- malian genome encodes much fewer phosphatase genes than kinase genes (Moorhead et al. 2007). This implicates that a phosphatase is much versatile than a kinase. A ubiquitously expressed protein Ser/Thr phosphatase-1 (PP1) is one of.

  10. TV borehole inspection and vacuum testing of roof strata

    International Nuclear Information System (INIS)

    Herget, G.

    1982-01-01

    To improve quality control of roof conditions, a program was carried out at Elliot Lake uranium mines in Ontario, Canada to test a portable TV camera system. This camera has a 29 mm diameter probe and is capable of identifying crack locations, crack width and approximate dip direction. The extent of fractures in the roof was checked with the aid of a vacuum system by placing packers in various boreholes and checking for communication. The removal of some rock bolts indicated an increase in fracture extent

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

    DEFF Research Database (Denmark)

    Jakobsen, Kristian Grube

    palaeocontinents with similar generic signatures include Laurentia, South China, Kazakhstan and southern Gondwanan margins. The studied Australian faunas do not exhibit a particular high marine biodiversity during this part of GOBE. It may be related to local palaeoenvironmental conditions, but as the investigated...

  12. Development of Methods for Gaseous Phase Geochemical Monitoring on the Surface and in the Intermediate Overburden Strata of Geological CO2 Storage Sites Développement de méthodes de suivi géochimique en phase gazeuse à la surface et dans la couverture intermédiaire des sites de stockage géologique du CO2

    Directory of Open Access Journals (Sweden)

    Pokryszka Z.

    2010-03-01

    Full Text Available The developments and results presented in this paper are taken from the work carried out as part of the GeoCarbon-Monitoring project, which was partly funded by the French National Research Agency (ANR. An important part of this project covers methods for gas monitoring on the surface as well as within the cap rock of geological CO2 storage sites. The work undertaken by INERIS was targeted at two specific approaches which are often recommended as essential for the monitoring of future storage sites: early detection (pre-alert, based on the sampling and analysis of gas at the bottom of the dedicated boreholes which are drilled from the surface into the intermediate cap rock strata; the detection and quantification of the gaseous flux of CO2 released from the ground into the atmosphere. These two approaches were developed in the laboratory successively and then applied and tested in-situ, under conditions that are as close as possible to those of the future storage sites. They offer the advantage of ensuring a direct measurement as well as providing real-time information on the presence or, on the contrary, the absence of CO2 leaks. The tests undertaken on a 200 meter deep borehole have shown that the detection of CO2 leaks passing through the intermediate overburden strata was possible thanks to the continuous sampling and analysis of the composition of the gas which accumulated at the bottom of the borehole. In particular, the detection of small releases of gas emanating from the surrounding rock gave rise to a number of good results. These releases may be a precursor to a larger leak. Likewise, it has been possible to take a sample and ensure the transit of gas over long distances, up to 1000 meters from the sampling point. This was done without causing any significant deformation or dilution of the initial gaseous signal, even for low amplitude leaks. These results allow us to envisage the implementation of a relatively simple system for

  13. Etude de la diagenèse organique des séries paleozoiques du bassin de Sbaa (Algérie). Approche géochimique et pétrologique.

    OpenAIRE

    Laggoun-Défarge, Fatima

    1987-01-01

    The Sbaa basin is located in the West-Central Province of the Algerian Sahara. It essentially consists of Palaeozoic shales and sandstones ranging from Cambro-Ordovician to Namurian, overfolded by thin Mesozoic strata. An oil occurrence in the Sbaa sandstone Formation (Tournaisian age; 500 m deep, 22 millions tons of actual reserves) makes the basin distinctive in an area rich in gas fields. The geochemical and petrological studies of organic matter (OM) (160 samples from 9 wells) showed that...

  14. Migrated hydrocarbons in outcrop samples: revised petroleum exploration directions in the Tarim Basin

    Energy Technology Data Exchange (ETDEWEB)

    Li, Maowen; Snowdon, Lloyd [Geological Survey of Canada, Calgary, AB (Canada); Xiao, Zhongyao [CNPC Tarim Petroleum Exploration Bureau, Kuerle, Xinjiang (China); Lin, Renzi [Petroleum Univ., Changping, Beijing (China); Wang, Peirong; Hou, Dujie [Jianghan Petroleum Univ., Hubei (China); Zhang, Linye [SINOPEC Shengli Petroleum Bureau, Dongying, Shandong (China); Zhang, Shuichang; Liang, Digang [Research Inst. of Petroleum Exploration and Development, Beijing (China)

    2000-07-01

    The application of age-specific biomarker distributions established from mature exploration areas of the Tarim Basin, northwestern China, indicates that most Carboniferous-Permian outcrop samples in the eastern segment of the Southwest Depression, previously believed to have significant petroleum source potential, in fact contain migrated hydrocarbons derived from Cambrian-Lower Ordovician strata. New geochemical results have led to a major revision of petroleum exploration directions in this area. (Author)

  15. Carbonate rocks of the Seward Peninsula, Alaska: Their correlation and paleogeographic significance

    Science.gov (United States)

    Dumoulin, Julie A.; Harris, Alta; Repetski, John E.

    2014-01-01

    Paleozoic carbonate strata deposited in shallow platform to off-platform settings occur across the Seward Peninsula and range from unmetamorphosed Ordovician–Devonian(?) rocks of the York succession in the west to highly deformed and metamorphosed Cambrian–Devonian units of the Nome Complex in the east. Faunal and lithologic correlations indicate that early Paleozoic strata in the two areas formed as part of a single carbonate platform. The York succession makes up part of the York terrane and consists of Ordovician, lesser Silurian, and limited, possibly Devonian rocks. Shallow-water facies predominate, but subordinate graptolitic shale and calcareous turbidites accumulated in deeper water, intraplatform basin environments, chiefly during the Middle Ordovician. Lower Ordovician strata are mainly lime mudstone and peloid-intraclast grainstone deposited in a deepening upward regime; noncarbonate detritus is abundant in lower parts of the section. Upper Ordovician and Silurian rocks include carbonate mudstone, skeletal wackestone, and coral-stromatoporoid biostromes that are commonly dolomitic and accumulated in warm, shallow to very shallow settings with locally restricted circulation. The rest of the York terrane is mainly Ordovician and older, variously deformed and metamorphosed carbonate and siliciclastic rocks intruded by early Cambrian (and younger?) metagabbros. Older (Neoproterozoic–Cambrian) parts of these units are chiefly turbidites and may have been basement for the carbonate platform facies of the York succession; younger, shallow- and deep-water strata likely represent previously unrecognized parts of the York succession and its offshore equivalents. Intensely deformed and altered Mississippian carbonate strata crop out in a small area at the western edge of the terrane. Metacarbonate rocks form all or part of several units within the blueschist- and greenschist-facies Nome Complex. The Layered sequence includes mafic meta¬igneous rocks and

  16. Significance of detrital zircons in upper Devonian ocean-basin strata of the Sonora allochthon and Lower Permian synorogenic strata of the Mina Mexico foredeep, central Sonora, Mexico

    Science.gov (United States)

    Poole, F.G.; Gehrels, G.E.; Stewart, John H.

    2008-01-01

    U-Pb isotopic dating of detrital zircons from a conglomeratic barite sandstone in the Sonora allochthon and a calciclastic sandstone in the Mina Mexico foredeep of the Minas de Barita area reveals two main age groups in the Upper Devonian part of the Los Pozos Formation, 1.73-1.65 Ga and 1.44-1.42 Ga; and three main age groups in the Lower Permian part of the Mina Mexico Formation, 1.93-1.91 Ga, 1.45-1.42 Ga, and 1.1-1.0 Ga. Small numbers of zircons with ages of 2.72-2.65 Ga, 1.30-1.24 Ga, ca. 2.46 Ga, ca. 1.83 Ga, and ca. 0.53 Ga are also present in the Los Pozos sandstone. Detrital zircons ranging in age from 1.73 to 1.65 Ga are considered to have been derived from the Yavapai, Mojave, and Mazatzal Provinces and their transition zones of the southwestern United States and northwestern Mexico. The 1.45-1.30 Ga detrital zircons were probably derived from scattered granite bodies within the Mojave and Mazatzal basement rocks in the southwestern United States and northwestern Mexico, and possibly from the Southern and Eastern Granite-Rhyolite Provinces of the southern United States. The 1.24-1.0 Ga detrital zircons are believed to have been derived from the Grenville (Llano) Province to the east and northeast or from Grenvilleage intrusions or anatectites to the north. Several detrital zircon ages ranging from 2.72 to 1.91 Ga were probably derived originally from the Archean Wyoming Province and Early Paleoproterozoic rocks of the Lake Superior region. These older detrital zircons most likely have been recycled one or more times into the Paleozoic sandstones of central Sonora. The 0.53 Ga zircon is believed to have been derived from a Lower Cambrian granitoid or meta-morphic rock northeast of central Sonora, possibly in New Mexico and Colorado, or Oklahoma. Detrital zircon geochronology suggests that most of the detritus in both samples was derived from Laurentia to the north, whereas some detritus in the Permian synorogenic foredeep sequence was derived from the evolving accretionary wedge to the south. Compositional and sedimentological differences between the continental-rise Los Pozos conglomeratic barite sandstone and the foredeep Mina Mexico calciclastic sandstone imply different depositional and tectonic settings. ?? 2008 The Geological Society of America.

  17. A Systems Approach to Identifying Exploration and Development Opportunities in the Illinois Basin: Digital Portifolio of Plays in Underexplored Lower Paleozoic Rocks [Part 1 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Seyler, Beverly; Harris, David; Keith, Brian; Huff, Bryan; Lasemi, Yaghoob

    2008-06-30

    This study examined petroleum occurrence in Ordovician, Silurian and Devonian reservoirs in the Illinois Basin. Results from this project show that there is excellent potential for additional discovery of petroleum reservoirs in these formations. Numerous exploration targets and exploration strategies were identified that can be used to increase production from these underexplored strata. Some of the challenges to exploration of deeper strata include the lack of subsurface data, lack of understanding of regional facies changes, lack of understanding the role of diagenetic alteration in developing reservoir porosity and permeability, the shifting of structural closures with depth, overlooking potential producing horizons, and under utilization of 3D seismic techniques. This study has shown many areas are prospective for additional discoveries in lower Paleozoic strata in the Illinois Basin. This project implemented a systematic basin analysis approach that is expected to encourage exploration for petroleum in lower Paleozoic rocks of the Illinois Basin. The study has compiled and presented a broad base of information and knowledge needed by independent oil companies to pursue the development of exploration prospects in overlooked, deeper play horizons in the Illinois Basin. Available geologic data relevant for the exploration and development of petroleum reservoirs in the Illinois Basin was analyzed and assimilated into a coherent, easily accessible digital play portfolio. The primary focus of this project was on case studies of existing reservoirs in Devonian, Silurian, and Ordovician strata and the application of knowledge gained to future exploration and development in these underexplored strata of the Illinois Basin. In addition, a review of published reports and exploration in the New Albany Shale Group, a Devonian black shale source rock, in Illinois was completed due to the recent increased interest in Devonian black shales across the United States. The New

  18. A importância da saúde bucal para adolescentes de diferentes estratos sociais do município de Ribeirão Preto La importancia de la salud bucal para los adolescentes de diferentes estratos sociales del municipio de Ribeirão Preto The importance of bucal health for adolescents of different social strata of Ribeirão Preto

    Directory of Open Access Journals (Sweden)

    Marina Sá Elias

    2001-01-01

    Full Text Available O objetivo do presente estudo é conhecer a importância da saúde bucal para adolescentes de diferentes estratos sociais, identificando a importância da estética dental, e o cuidado que estes dispensam em relação a sua saúde bucal. O processo metodológico adotado nesta investigação é de natureza qualitativa, utilizando como técnica de coleta de dados a entrevista semi-estruturada. Conhecemos a importância da saúde bucal em vários contextos de suas vidas, como na aparência pessoal, na sexualidade, no emprego, e na saúde geral. Esta investigação permite-nos conhecer as motivações para os adolescentes preservarem sua saúde bucal, o que acreditamos ser muito válido no intuito de desenvolvermos a promoção de saúde através da educação em saúde.El objetivo del presente estudio es conocer la importancia de la salud bucal para los adolescentes de diferentes estratos sociales, identificando la importancia de la estética dental y el cuidado que estos realizan en relación con su salud bucal. El proceso metodológico adoptado en esta investigación es de naturaleza cualitativa, utilizando como técnica de recolección de datos la entrevista semi-estructurada. Conocimos la importancia de la salud bucal en varios contextos de sus vidas, como en la apariencia personal, en la sexualidad, en el empleo y en la salud en general. Esta investigación nos permitió conocer las motivaciones que tienen los adolescentes para preservar su salud bucal, lo cual creemos será muy valioso en desarrollar programas de promoción de la salud a través de la educación en salud.The objective of the present study is to know the importance of buccal health for adolescents of different social strata, identifying the importance of dental aesthetics, and the care that these students take in relation to their buccal health. The methodological process adopted in this investigation is of qualitative nature, using as technique of collection of data the semi

  19. Paleozoic stratigraphy and tectonics in northernmost Nevada: Implications for the nature of the Antler orogeny

    Energy Technology Data Exchange (ETDEWEB)

    Ketner, K.B. (Geological Survey, Denver, CO (United States)); Ehman, K.D. (Exxon Production Research Co., Houston, TX (United States)); Repetski, J.E.; Stamm, R.G.; Wardlaw, B.R. (Geological Survey, Reston, VA (United States))

    1993-04-01

    Recent mapping and revised ages have clarified geologic relations in northern Nevada. In the Bull Run Mountains-Copper Mountains area, Proterozoic quartzite, phyllite, marble, and greenstone are overlain successively, depositionally, and nearly concordantly by the Cambrian Prospect Mountain Quartzite, Pioche Shale, and Eldorado Dolomite; the Cambrian to Ordovician Tennessee Mountain Formation composed of limestone, siltstone, and greenstone; the Ordovician Valmy Formation composed of a lower member of greenstone, limestone, mudstone, and chert, and an upper member of quartzite and argillite; and, disconformably by a Mississippian sequence of interbedded conglomerate, limestone, siltstone, and greenstone. The Prospect Mountain, Pioche, and Eldorado form a relatively shallow-water, shelf sequence containing trilobites and displaying cross-bedding, ooliths, oncolites, and fenestral fabric. The overlying Tennessee Mountain and Valmy are devoid of such features and contain many black, finely laminated, and graded strata, suggesting a deeper-water environment. This upper Proterozoic to Permian sequence is interpreted as indicating: (1) increased tectonic subsidence or sea-level rise in the latter part of the Cambrian; (2) elevation above sea level and erosion of Devonian, Silurian, and Upper Ordovician rocks in earliest Mississippian; (3) subsidence below sea level in later Early Mississippian; (4) elevation above sea level with sporadic, moderate deformation, and local, deep erosion in medial Pennsylvanian; (5) subsidence below sea level in medial Pennsylvanian or later; (6) intermittent eruption of basic volcanics peaking in Early Ordovician and again in Mississippian. The disconformable relation between the Valmy Formation and overlying Mississippian strata indicates that the Antler orogeny of earliest Mississippian age, here consisted primarily of uplift and deep erosion. Evidence of strong Early Mississippian folding and contractional faulting is not apparent.

  20. First record of Telephina (Trilobita from the Ordovician of northeastern Estonia and its stratigraphical implications

    Directory of Open Access Journals (Sweden)

    Helje Pärnaste

    2011-06-01

    Full Text Available For the first time a telephinid trilobite was recorded from the shallow-water rocks of the North Estonian Confacies Belt in the oil-shale mining area of northeast Estonia. A cranidium of Telephina (Telephops biseriata (Asklund was collected from a loose boulder of the kerogenous limestone of the Viivikonna Formation, Kukruse Stage, together with a rich assemblage of other trilobites, bryozoans, ostracods and rare graptolites. In its type area Jämtland, Sweden, T. biseriata occurs together with Pygodus anserinus and Hustedograptus teretiusculus in the Ståltorp Limestone Member of the Andersö Shale Formation, marking the latest Darriwilian. The occurrence in the North Estonian Confacies Belt of Telephina, known as a pelagic trilobite inhabiting deeper-water areas, probably reflects a transgression event at this time. Together with T. biseriata, other trilobite taxa such as Remopleurides and Lonchodomas, common in the Hustedograptus teretiusculus Biozone in deeper-water areas, arrive in the North Estonian Confacies Belt. Graptolites from the other loose boulders at the same locality have been identified as Hustedograptus cf. uplandicus, which occur together with a few dendroids.

  1. 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

    benthic biodiversity in this clastic-dominated shallow-water palaeoenvironment situated along the margin of northeastern Gondwana. The faunas from the Stairway Sandstone are generally of low diversity and dominated by bivalves but include several animal groups, with trilobites representing 25......% of the entire shelly fauna. Thirteen trilobite taxa are described from the Stairway Sandstone; the fauna displays a high degree of endemism. One new species, Basilicus (Parabasilicus) brumbyensis sp. nov. is described....

  2. Fracture toughness testing of core from the Cambro-Ordovician Section on the Oak Ridge Reservation

    International Nuclear Information System (INIS)

    Lemiszki, P.J.; Landes, J.D.

    1996-01-01

    The modified ring test was used to determine the mode I fracture toughness of bedrock cores from the DOE Oak Ridge Reservation in east Tennessee. Low porosity sandstones, limestones, and dolostones from the lower part of the Paleozoic section in Copper Creek and Whiteoak Mountain thrust sheets were sampled. In general, the average mode I fracture toughness decreases from sandstone, dolostone, and limestone. The fracture toughness of the limestones varies between rock units, which is related to different sedimentologic characteristics. Quality of results was evaluated by testing cores of Berea Sandstone and Indiana Limestone, which produced results similar to published results

  3. Trans-Atlantic application of the Baltic Middle and Upper Ordovician carbon isotope zonation

    Directory of Open Access Journals (Sweden)

    Stig M. Bergström

    2015-02-01

    Full Text Available Application of the recently introduced Baltic d13C isotope zonation to a composite North American Darriwilian through Hirnantian succession shows that in most intervals there is good trans-Atlantic agreement not only between the isotope zones but also with the available biostratigraphic data. This indicates that this isotope zonation is a useful tool for improving previously uncertain long-distance correlations.

  4. 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

    , but in the dististele they occur in the angles. This range of morphologies would have led to their inclusion in at least two morphogenera if they had not been closely associated; as they belong to a single biological species, they have been ‘lumped’ together herein. This is a rare contribution to our knowledge......; the mesistele of similar gross morphology is more slender with a regularly heteromorphic column and a similarly wide axial canal; the dististele is a terminal dendritic radice with a pentastellate axial canal. In the mesistele, the meric sutures correspond to the centres of the sides of the column...

  5. Tectonic evolution of Tarim basin in Cambrian–Ordovician and its ...

    Indian Academy of Sciences (India)

    For different geodynamic settings of surrounding regions, there are different charac- teristics of depositional lithologies and lithofacies, sea-level change, distribution and migration of sed- imentary facies, etc., in the Tarim basin. Under the condition of regional extensional dynamic setting around Tarim Plate, there formed the ...

  6. Tectonic evolution of Tarim basin in Cambrian–Ordovician and its ...

    Indian Academy of Sciences (India)

    southwest boundary and Altyn fault zone (Altyn oro- genic belt) as the southeast boundary, respectively. (figure 1) (Huang et al. 1990; Xiao et al. 1990, 1991;. Zhang 1994; Tang et al. 1995; He et al. 2005). 2.1 North boundary. The Tarim Plate is adjacent to the Kazakhstan. Plate on the north. The fault at north margin.

  7. Characteristics, distribution and diagenetic stages of chert in the La Silla Formation (Lower Ordovician, Argentine Precordillera

    Directory of Open Access Journals (Sweden)

    Mariana M. Raviolo

    2009-12-01

    Full Text Available The late Cambrian - late Tremadocian La Silla Formation is a carbonate unit of the eastern Precordillera in Argentina whose facies indicate a shallow platform environment. Until this moment, there were no studies that referred to the diagenetic evolution of these rocks. The present study involves the characteristics and distribution of the silicification that affects this unit and determines its different diagenetic stages through petrographic (with cathodoluminescence support and stratigraphic analyses. An early diagenetic chert, in a stage previous to the compactation, was observed. This chert is related to silica-rich seawater in contact with permeable and porous sediments. A later pulse of chert, associated with fracturing, also occurs. The knowledge provided by the characteristics and distribution of chert in these carbonates is significant, especially when considering that the La Silla Formation in San Juan province is the most quarried unit for the elaboration of lime.A Formação La Silla (Neo Cambriano-Neo Tremadociano é formada por depósitos carbonáticos da região da Pré-Cordilheira leste, Argentina. As faciologias encontradas em tais depósitos indicam um ambiente de deposição caracterizado por uma plataforma rasa. Até o momento, nenhum estudo tratou especificamente da evolução diagenética dessas rochas. O presente estudo envolve as características e distribuição da silicificação que afeta esta formação e apresenta os diferentes estágios diagenéticos ocorridos, através de análises petrográficas (auxiliadas por catodoluminescência e estratigráficas. Foi identificado um pulso precoce de silicificação, anterior ao processo de compactação das rochas afetadas. Esta silicificação foi favorecida pela presença de água do mar rica em sílica em contato com sedimentos porosos e permeáveis. Também foi identificado um pulso de silicificação tardia, associado a eventos de fraturamento das rochas. O conhecimento adquirido sobre as características e a distribuição da silicificação nestes depósitos carbonáticos é importante, especialmente quando se considera que a Formação La Silla, na Província de San Juan, é a formação mais minerada para a produção de calcário.

  8. Upper Ordovician conodont biostratigraphy and biofacies from the Sigang section, Neixiang, Henan, central China

    DEFF Research Database (Denmark)

    Jing, Xiuchun; Stouge, Svend; Ding, Ling

    2017-01-01

    The 186-m-thick Shiyanhe Formation exposed at the Sigang section, Neixiang area, Henan Province, central China has been investigated for conodonts. The collected 33 samples yielded 8858 conodont specimens. The conodonts are referred to 15 genera and 34 species, but four species cannot be positively...... been established using multivariate statistical techniques on the conodont assemblage. As their turnovers were related to sea-level changes, the conodont biofacies are used to demonstrate the transgressive-regressive pattern in the studied section....

  9. Ordovician conodonts from the Mithaka Formation (Georgina Basin, Australia). Regional and paleobiogeographical implications

    OpenAIRE

    KUHN, T.; BARNES, C.

    2005-01-01

    The systematic analysis of conodonts from the previously unstudied Mithaka Formation (Georgina Basin) yielded 1366 identifiable elements, representing 25 species and 21 genera. One new species was recovered and identified, Triangulodus mithakensis n. sp. Four other new species are described in open nomenclature as Bergstroemognathus? n. sp. A, ?Periodon n. sp. A, Phragmodus n. sp. A and Taoqupognathus n. sp. A. The Mithaka Fm fauna shows similarity with conodonts from several previous Austral...

  10. Resolving early Mid-Ordovician (Kundan) bioevents in the East Baltic based on brachiopods

    DEFF Research Database (Denmark)

    Rasmussen, Christian Mac Ørum; Harper, David Alexander Taylor

    2008-01-01

    Bed-by-bed sampling of brachiopods from selected Kundan Stage localities in the East Baltic has permitted the construction of a-diversity curves, unprecedented in detail from this particular stage and region. These a-diversity curves can be correlated between the investigated sections, along...... an east to west transect of some 200 km and indicate bioevents associated with intervals of increased palaeo-water depth. The highest peaks in a-diversity occur when biofacies analysis and sedimentological evidence indicate drowning events. The events involve mainly taxa endemic to the Baltic province...

  11. High-resolution stable isotope stratigraphy of the upper Cambrian and Ordovician in the Argentine Precordillera

    DEFF Research Database (Denmark)

    Sial, A.N.; Peralta, S.; Gaucher, C.

    2013-01-01

    We report the occurrence of important carbon isotope excursions in early Paleozoic formations of the Eastern and Central Argentine Precordillera. The Steptoean positive isotope carbon excursion (SPICE) is known from North America, Kazakhstan, South China, Australia and South America, and the nega...

  12. Tectonic evolution of Tarim basin in Cambrian–Ordovician and its ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 125; Issue 2 ... 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 ...

  13. Graptolite community responses to global climate change and the late ordovician mass extinction

    Czech Academy of Sciences Publication Activity Database

    Sheets, H. D.; Melchin, M. J.; Loxton, J.; Štorch, Petr; Carlucci, K. L.; Hawkins, A. D.

    2016-01-01

    Roč. 113, č. 30 (2016), s. 8380-8385 ISSN 0027-8424 R&D Projects: GA AV ČR IAA301110908 Institutional support: RVO:67985831 Keywords : abundance * climate change * extinction * macroevolution * selection Subject RIV: DB - Geology ; Mineralogy Impact factor: 9.661, year: 2016

  14. Geology of the Severnaya Zemlya Archipelago and the North Kara Terrane in the Russian high Arctic

    Science.gov (United States)

    Lorenz, Henning; Männik, Peep; Gee, David; Proskurnin, Vasilij

    2008-05-01

    The Severnaya Zemlya Archipelago is located at 80°N near the continental shelf break, between the Kara and Laptev seas. Sedimentary successions of Neoproterozoic and Palaeozoic age dominate the bedrock geology. Together with Northern Tajmyr, Severnaya Zemlya constitutes the main land areas of the North Kara Terrane (NKT), which is inferred here to have been a part of the Timanide margin of Baltica, i.e. an integral part of Baltica at least since the Vendian. Vendian turbidites derived from the Timanide Orogen are inferred to have been deposited on Neoproterozoic greenschist facies, granite-intruded basement. Shallow-water siliclastic deposition in the Early to Mid-Cambrian was followed by highly organic-rich shales in the Late Cambrian and influx of more turbidites. An episode of folding, the Kan’on River deformation, separates these formations from the overlying Tremadocian conglomerates and sandstones. In the Early Ordovician, rift-related magmatic rocks accompanied the deposition of variegated marls, sandstones, carbonates and evaporites. Dark shales and gypsiferous limestones characterise the Mid-Ordovician. Late Ordovician quartz-sandstones mark a hiatus, followed by carbonate rocks that extend up into and through most of the Silurian. The latter give way upwards into Old Red Sandstones, which are inferred to have been deposited in a Caledonian foreland basin. Deformation, reaching the area in the latest Devonian or earliest Carboniferous and referred to as the Severnaya Zemlya episode, is thought to be Caledonian-related. The dominating E-vergent structure was controlled by décollement zones in Ordovician evaporite-bearing strata; detachment folds and thrusts developed in the west and were apparently impeded by a barrier of Ordovician igneous rocks in the east. Below the décollement zones, the Neoproterozoic to Early Ordovician succession was deformed into open to close folds. The exposed strata in the lower structural level have been juxtaposed with

  15. Peltephilidae and Mesotheriidae (Mammalia) from late Miocene strata of Northern Chilean Andes, Caragua

    Science.gov (United States)

    Montoya-Sanhueza, Germán; Moreno, Karen; Bobe, René; Carrano, Matthew T.; García, Marcelo; Corgne, Alexandre

    2017-04-01

    Until now, only one Cenozoic fossil mammal from the Chilean Precordillera (Arica and Parinacota Region) has been reported, Caraguatypotherium munozi (Mesotheriidae: Notoungulata). In this study, we describe a fourth specimen of C. munozi and a new armadillo species, Epipeltephilus caraguensis (Peltephilidae: Cingulata), both collected from a new site closer to the fossiliferous outcrops of the Caragua area (Serravallian - Tortonian). E. caraguensis differs from other members of the family in having: two sulci in the articular surface of the mobile osteoderm; having a tubular, rough and raised anterior edge; a conspicuous transverse depression; and four widely spaced foramina. This taxon represents the youngest known peltephilid from intermediate latitudes and indicates a wide geographic distribution (Patagonia to Central Andes) of the family just prior to its extinction. The new mesothere specimen is 19% larger than previous records. The revision of the dental features of C. munozi allowed the identification of an ambiguous trait in its original diagnosis, i.e. an enamel fracture was misinterpreted with the presence of a posterior sulcus on the talonid of the m3, suggesting that further taxonomic and systematic revision for the Caragua mesothere is necessary. Although the fossil record from the Caragua area is still scarce, mesotheriines seem to be abundant at this latitude, just as has been observed at several early to late Miocene sites such as Chucal (Chile), Cerdas and Nazareno (Bolivia), as well as in southern regions such as Arroyo Chasicó and Mendoza (Argentina). The presence of a new peltephilid species in Caragua sustains the hypothesis of provincialism during the Miocene in intermediate latitudes. Our findings also provide further support for probable faunal movements between intermediate and higher latitudes rather than to lower ones.

  16. Paleomagnetic results of Neogene strata in Eastern Vietnam and their paleogeographic Implications

    Science.gov (United States)

    Weiwei, C.; Zhao, X.; Liu, Z.; Dong Pha, P.

    2017-12-01

    Neogene paleomagnetic data from the Vietnam, southeastern margin of the Indochina Block, are essential to reconstruct post-collisional paleogeography. This is key to understanding the evolution of the western South China Sea and verifying the model of extrusion tectonic. Mid-Miocene siltstone of the Song Ba Formation and Pliocene basalt were sampled from Phu Tue area, eastern Vietnam. Paleomagnetic samples were collected using a gasoline-powered drill and a magnetic compass mounted on an orienting device. We corrected for the effect of local magnetic anomalies on magnetic orientation by taking solar azimuths using a sun compass. For most samples, the discrepancy between the two compass readings is within 3°. Remanent magnetization measurements were carried out with 2G-755-4K cryogenic magnetometers, installed in the Plaleomagnetism Laboratory, Tongji University, Shanghai. All the instruments are located in a shielded room with residual fields less than 200 nT. The anisotropy of magnetic susceptibility (AMS) results of four siltstone sites (sites 2, 6, 9, 10) indicate the siltstone preserve a normal sedimentary magnetic fabric. The other sites of the AMS (including basalt sites) show that the directions of K1, K2, K3 are scattered without any regulation. The thermal demagnetization and AF demagnetization were performed on specimens and stepwise demagnetization up to 600°C or 150 mT. ChRM directions were determined for all the specimens using principal component analysis. The directions obtained from Neogene rocks are far from the present geomagnetic field (PGF) and include antipodal dual polarities, suggesting a primary origin. A visible fluctuation in paleomagnetic direction from one site to another is evident from the results. Shallow inclination are obtained from most samples which range of 7.4° to 21.5°. The siltstone declination range of 16.8° to 34.5° while the basalt declination rang of 178.3° to 335.0°. This wide range of direction fluctuation suggests a long record of secular variation and has been sufficiently averaged out by formation mean calculations. The preliminary data suggest that that southern Indochina Block was at a mean paleolatitude of 5° 10° N during the Paleogene. The relative rotation should be caused by the local deformation and the motion of the entire lithospheric block.

  17. Multiple stages of aqueous alteration along fractures in mudstone and sandstone strata in Gale Crater, Mars

    Science.gov (United States)

    Yen, A. S.; Ming, D. W.; Vaniman, D. T.; Gellert, R.; Blake, D. F.; Morris, R. V.; Morrison, S. M.; Bristow, T. F.; Chipera, S. J.; Edgett, K. S.; Treiman, A. H.; Clark, B. C.; Downs, R. T.; Farmer, J. D.; Grotzinger, J. P.; Rampe, E. B.; Schmidt, M. E.; Sutter, B.; Thompson, L. M.; MSL Science Team

    2017-08-01

    The Mars rover Curiosity in Gale crater conducted the first-ever direct chemical and mineralogical comparisons of samples that have clear parent (unaltered) and daughter (altered) relationships. The mineralogy and chemistry of samples within and adjacent to alteration halos in a sandstone formation were established by the Chemistry and Mineralogy (CheMin) X-ray diffraction (XRD) instrument and the Alpha Particle X-ray Spectrometer (APXS), respectively. The Stimson formation sandstones unconformably overlie the Murray mudstone formation and represent the youngest stratigraphic unit explored by Curiosity to date. Aqueous alteration of the parent sandstone resulted in a loss of half of the original crystalline mineral phases and a three-fold increase in X-ray amorphous material. Aqueous fluids extensively leached Mg, Al, Mn, Fe, Ni, Zn and other elements from the parent material, decreased the pyroxene to feldspar ratio by a factor of two, introduced Ca and mixed-cation sulfates, and both passively and actively enriched the silica content. Leaching of Mg, Al, Mn, Fe, Ni and Zn and enrichment of Si and S are also observed in alteration halos in the underlying mudstone. These observations are consistent with infiltration of subsurface fluids, initially acidic and then alkaline, propagating along fractures crosscutting the Stimson sandstone and Murray mudstone. The geochemistry and mineralogy suggest a complicated diagenetic history with multiple stages of aqueous alteration under a variety of environmental conditions (e.g. both low and moderate pH). The formation of these alteration halos post-dates lithification of the sandstones and mudstones and represents one of the youngest hydrogeologic events presently known to have occurred in Gale crater.

  18. Noble Gases as tracers of fluid migration in the Haynesville shale and overlying strata

    Science.gov (United States)

    Byrne, D. J.; Barry, P. H.; Lawson, M.; Ballentine, C. J.

    2017-12-01

    Noble gases are ideal tracers of physical processes and fluid provenance in crustal systems. Due to their inert nature, they are unaffected by chemical alteration, redox, or biological phenomena that fractionate other geochemical tracers. Noble gas analysis has been used to quantify fluid provenance, interactions, and ages in petroleum systems [1,2], but the effects of hydrocarbon migration on noble gas signatures have not been directly observed. The Haynesville Shale (East Texas & Louisiana), is exploited commercially for unconventional shale gas, but also acts as the source-rock for overlying conventional reservoirs. We present noble gas isotope and abundance data in samples collected from 9 natural gas wells sourced from the Haynesville Shale, as well as 21 from reservoirs in the overlying Cotton Valley (n=7), Travis Peak (n=9), and James (n=5) groups. Using a stratigraphic model, we observe systematic changes in the noble gas signatures as the fluids migrate from the Haynesville source rock to the overlying conventional accumulations. Helium isotope ratios (3He/4He) are strongly radiogenic in the Haynesville and stratigraphically older conventional reservoirs, with the younger reservoirs showing evidence of a mantle helium input. Argon isotope ratios (40Ar/36Ar) are strongly correlated with high 3He/4He, suggesting a similar provenance for radiogenic 40Ar and mantle 3He. Concentrations of groundwater-derived 36Ar are consistently higher in the conventional reservoirs than in the Haynesville shale, reflecting the greater interaction with groundwater during migration. However, 20Ne/36Ar ratios are not significantly different, suggesting that solubility-dependent partitioning is not simply dependent on vertical or horizontal migration distance. Krypton and xenon abundances are higher than expected for groundwater in all samples, a phenomenon that has been observed in many other hydrocarbon accumulations [3]. The excess Xe/Kr ratio is highest in the Haynesville itself, suggesting that this excess Xe and Kr originates from within the source-rock, and is subsequently shifted towards normal Xe/Kr values by mixing with groundwater-derived noble gases during migration. [1] Barry et al., 2016, GCA 194, 291-309; [2] Darrah et al., 2014, PNAS 111, 14076-81; [3] Zhou et al., 2005, GCA 69, 5413-28

  19. Stratigraphical framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf

    OpenAIRE

    Barron, A.J.M.; Lott, G.K.; Riding, J.B.

    2012-01-01

    The Stratigraphy Committee of the British Geological Survey (BGS) is undertaking a review of stratigraphical classification for all parts of Great Britain. Several Stratigraphical Framework Committees (SFC) have been established to review problematical issues for various parts of the stratigraphical column. Each SFC has the following terms of reference: • To review the lithostratigraphical nomenclature of designated stratigraphical intervals for a given region, identifying problems in clas...

  20. The influence of canopy strata on remotely sensed observations of savanna-woodlands

    International Nuclear Information System (INIS)

    Fuller, D.O.; Prince, S.D.; Astle, W.L.

    1997-01-01

    Upwelling radiance from savanna woodlands may originate from two separate layers: (1) the field layer, which is a mixture of soil, litter and herbs, and (2) the tree layer composed of woody parts and leaves. Unless detailed field data are available for a particular savanna location, it is unknown how the individual layers may influence the red and near-infrared signals and whether radiative interactions between layers are important. We employed an existing radiative transfer model (SAIL) in conjunction with a simple, single-scattering model to analyse the variation in Advanced Very High Resolution Radiometer (AVHRR) channel 1 and 2 response as well as NDVI for savanna-woodland vegetation in eastern Zambia. Linear fits between predicted and observed values of reflectance and NDVI were significant ( p 0.05) in the red and in NDVI, however, the model failed to explain a high proportion of the variation in near-infrared. Red and NDVI in sites where tree cover was high were also poorly modelled, which suggests that multiple interactions between canopy layers make a single-scattering model unreliable, particularly in the near-infrared. Modelled results were also compared to aircraft radiometer measurements provided by the integrated camera and radiometer instrument (ICAR). Simulations parameterized with field data suggest that the model may be used to infer tree and field layer influences at different points during the seasonal cycle. Results also suggest that the field layer dominated the signal in our savanna woodland sites throughout most points of the seasonal cycle, which is consistent with other canopy radiative-transfer studies. Simulations indicated that the tree layer was a relatively more important component of NDVI during the dry season when the field layer was largely senescent, accounting for 20-40 per cent of the satellite signal. (author)

  1. Analisis Pengaruh Faktor Kepribadian, Lingkungan Dan Demografis Terhadap Minat Kewirausahaan Mahasiswa Strata Satu Universitas Sumatera Utara

    OpenAIRE

    Rudy

    2010-01-01

    Universities’ graduates in Indonesia need relatively long time to get jobs, consequently unemployment can not be avoided against university graduates. Entrepreneurship is the key to settle the unemployment, hence entrepreneurship should be developed in campus. The problem statements of this research are 1) how strong is the influence of variables of personality, environment and demography towards entrepreneurship intention of students, 2) how strong is the influence of variables of needs ...

  2. Frasnian reef and basinal strata of West Central Alberta: A combined sedimentological and biostratigraphic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Weissenberger, J.A.W. (Imperial Oil Resources Ltd., Calgary, AB (Canada))

    1994-03-01

    The depositional history for the Frasnian in the Nordegg area is interpreted and illustrated on cross sections and paleogeographic maps. Carbonate deposition began with the flooding of the West Alberta Arch and the deposition of the upper Swan Hills Formation during the Lower asymmetrica Zone. Transgression in the Middle asymmetrica Zone initiated the basinal Cline Channel and Duvernay Formation shale deposition, while the time equivalent Cooking Lake Formation was deposited on the drowned Swan Hills platform. The overlying lower Leduc Formation shows backstepping and aggradational reef margin stacking patterns. Maximum relief from the carbonate platform to surrounding Duvernay Formation shale during the Upper asymmetrica Zone was 100 m. Aggradation and backstepping was repeated in the Ancyrognathus trianularis Zone, with syndepositional relief reaching 170 m at the Wapiabi Gap reef margin. Platfrom-margin profiles were controlled by physical factors such as dominant wind direction and currents. On the Ram Range the margin backstepped, but then aggraded at Cripple Creek. At Wapiabi Gap, to the north on the Bighorn Range, the margin was dominantly aggradational. Ireton Formation shale deposition was also influenced by currents. In the Lower gigas Zone, the Leduc carbonate platform reached a maximum syndepositional relief at 220 m. A change from dominantly biohermal to biostromal platform margins occurred. A prograding wedge of Ireton Formation shale filled much of the relief in the Cline Channel, while the upper Leduc platform was drowned. Finally, the progradational Nisku Formation was deposited during the Upper gigas Zone. 70 refs., 20 figs.

  3. Stratigraphy and petroleum possibilities of lower Upper Devonian (Frasnian and lower Framennian) strata, Southwestern Utah

    Science.gov (United States)

    Biller, Edward J.

    1976-01-01

    The lower Upper Devonian rocks in southwestern Utah--the Guilmette Formation and equivalents--represent a final regressive pulse of the major Late Devonian marine inundation of the Western Interior of the United States and record marine carbonate deposition on a wide continental shelf. They consist primarily of limestone, dolomite, and quartz arenite deposited in a shallow north-trending miogeosyncline, which constituted a single major basin of accumulation on this shelf. The Guilmette Formation and equivalents were deposited in shallow normal to hypersaline marine waters. The environments of deposition include: a moderate- to high-energy intertidal environment, a moderate-energy subtidal environment, a lower energy, deeper subtidal environment below effective wave base, and a high-energy environment in local shallow areas of mud mounds and bioherms. The carbonate deposition of the Guilmette Formation and equivalents was interrupted periodically by the deposition of quartz arenites. These may represent the breaking up of the miogeosynclinal-cratonic pattern of deposition. In most areas, the Guilmette and equivalents are overlain by a thin transgressive marine quartz arenite deposit--the Cove Fort Quartzite and basal Leatham equivalent. Previous paleontologic evidence indicated a general Middle to Late Devonian age for the Guilmette Formation. The present study narrows this range and suggests that the age of the Guilmette Formation and its equivalents is late Middle Devonian (Stringocephalus brachiopod zone) to early Late Devonian (Uppermost Palmatolepis gigas conodont zone). Available subsurface data suggest that the petroleum possibilities of the Guilmette Formation and equivalents in southwestern Utah are poor. Several tests have penetrated .the interval with only minor shows of oil in rocks with low porosity and permeability. Nevertheless, many outcrop samples of the same interval, appear to have excellent porosity and permeability and a strongly fetid odor,

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

    OpenAIRE

    Soares, Emílio Alberto Amaral; Dino, Rodolfo; Soares, Dominicky Peres; Antonioli, Luzia; Silva, Marco Antônio Lima da

    2015-01-01

    ABSTRACT The scarcity of stratigraphic data has hindered the demarcation of the outcropping area of Miocene deposits of the Amazon Basin, represented informally by the Novo Remanso Formation. Moreover, this unit is characterized by a sparse and irregular geographic distribution due to its sedimentological features and rare fossil content. Miocene deposits cropping out in central Amazonas Basin area were described in sedimentological terms and analyzed palynologically. All analyses were undert...

  5. Evaluation of strategies for hydrogeologic characterization of a repository area in marine and fluvioterrestrial sedimentary strata

    International Nuclear Information System (INIS)

    Andrews, R.W.; Hufschmied, P.; Loew, S.; Black, J.; Dershowitz, W.

    1991-01-01

    The present paper describes a comprehensive repository development strategy that includes a quantitative approach to quantify (i) the uncertainty about the existence of hydrogeologic key features and (ii) one's ability to reduce this uncertainty by a phased field exploration program. The quantitative methodology is based on the premise that one of the primary goals of the site exploration program is to intersect, detect, and characterize key hydrogeologic features which have some likelihood of forming preferential pathways through the geosphere. The success of the exploration strategy is determined by the probability that adequate information will be obtained by the exploration program to confirm either the absence of the presence of preferential pathways at the repository site. The application of the methodology demonstrated the utility of the approach and indicated some key differences between the two host rocks under consideration. 7 figs; 1 tab.; 10 refs

  6. Upper limb musculoskeletal abnormalities in type 2 diabetic patients in low socioeconomic strata in Pakistan

    Directory of Open Access Journals (Sweden)

    Kidwai Saera Suhail

    2013-01-01

    Full Text Available Abstract Background Musculoskeletal manifestations of diabetes in the upper limb are well recognized. No data has been available in this regard from Pakistan. Our aim was to find out the frequency of upper limb musculoskeletal abnormalities in diabetic patients. Methods This was an observational study in which type 2 diabetes patients attending our diabetic clinic were enrolled along with age and gender matched controls. Data was analyzed on SPSS 16. Results In total, 210 Type 2 diabetics (male 34.3%, female 65.7% and 203 controls (male 35%, female 65% were recruited. The mean age was 50.7± 10.2 years in diabetic group as compared to 49.5±10.6 years in the control group. The frequencies of hand region abnormalities were significantly higher in the diabetic subjects as compared to the controls (20.4%, p-value Conclusion A higher frequency of upper limb musculoskeletal abnormalities was observed in Type 2 diabetic patients as compared to control group.

  7. Neogene magnetic imprint detected in the Jurassic-Cretaceous limestone strata in the Tethyan realm

    Czech Academy of Sciences Publication Activity Database

    Krs, Miroslav; Pruner, Petr; Venhodová, Daniela

    2000-01-01

    Roč. 51, č. 3 (2000), s. 196-197 ISSN 0016-7738. [New Trends in Geomagnetism /7./. Moravany, 19.06.2000-25.06.2000] R&D Projects: GA ČR GA205/99/0594 Institutional research plan: CEZ:AV0Z3013912 Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.486, year: 1999

  8. PEMAHAMAN TEORI DATA WAREHOUSE BAGI MAHASISWA TAHUN AWAL JENJANG STRATA SATU BIDANG ILMU KOMPUTER

    Directory of Open Access Journals (Sweden)

    Harco Leslie Hendric Spits Warnars

    2015-01-01

    Full Text Available As a Computer scientist, a computer science students should have understanding about database theory as a concept of data maintenance. Database will be needed in every single human real life computer implementation such as information systems, information technology, internet, games, artificial intelligence, robot and so on. Inevitably, the right data handling and managament will produce excellent technology implementation. Data warehouse as one of the specialization subject which is offered in computer science study program final semester, provide challenge for computer science students.A survey was conducted on 18 students of early year of computer science study program at Surya university and giving hypothesis that for those students who ever heard of a data warehouse would be interested to learn data warehouse and on other hand, students who had never heard of the data warehouse will not be interested to learn data warehouse. Therefore, it is important that delivery of the Data warehouse subject material should be understood by lecturers, so that students can well understoodwith the data warehouse.

  9. Development of subsidence profile functions for longwall mining associated with weak floor strata considering time effects

    International Nuclear Information System (INIS)

    Yu, Z.; Chugh, Y.P.; Yang, G.

    1994-01-01

    Subsidence profile functions for longwall mining in the Illinois Coal Basin were developed for both the headgate and tailgate sides based on field observations of surface subsidence over several longwall panels. One function was applied to predict the subsidence profile for a longwall panel in another Illinois Coal Basin mine, where a good correlation between the predicted and measured results was achieved. Attempts were also made to develop subsidence profile functions including time effect. 4 refs., 9 figs., 1 tab

  10. Growth in indigenous and nonindigenous Chilean schoolchildren from 3 poverty strata.

    Science.gov (United States)

    Bustos, P; Amigo, H; Muñoz, S R; Martorell, R

    2001-10-01

    This study sought to determine whether the short stature of Mapuche children, an indigenous group in Chile, reflects poverty or genetic heritage and whether the international reference population, derived from studies of US children of mostly European origin, is appropriate for assessing growth failure in indigenous peoples of the Americas. The study assessed 768 schoolchildren of Mapuche and non-Mapuche ancestry, aged 6 to 9 years, living under conditions of extreme, medium, and low poverty. Growth retardation was strongly related to poverty in both ethnic groups. Within poverty levels, there were no significant differences in stature between ethnic groups, and in low-poverty areas in Santiago, the capital city, mean stature was only slightly less than in the reference population. Poverty, not ancestry, explains the short stature of Mapuche children, and use of the international reference to assess growth in this population is appropriate.

  11. Tephra layers as correlation tools of neogene coal-bearing strata from the Kenai lowland, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Reinink-Smith, L.M. [Univ. of Alaska, Fairbanks, AK (United States)

    1995-03-01

    Thirty-two tephra layers, exposed in coal beds of the Miocene and Pliocene Beluga and Sterling Formations along the shores of the Kenai lowland on the northwestern Kenai Peninsula, Alaska, were studied in detail to improve the geochronology and regional correlation of the Sterling Formation and test prior correlations that were based on palynology and physical tracing of beds over short distances. Published radiogenic isotope data suggest an age span of approximately 4 m.y. for the Sterling Formation at this location but give discordant ages for individual samples depending on dating techniques. A crystal-rich tephra layer near the middle of the section was traced across the Kenai lowland as one or two ash falls based on stratigraphic position, inertinite contents of adjacent coal, geochemical and mineralogical analyses, and individual characteristics. A pumice-rich layer deposited near the top of the Sterling Formation is preserved at two localities on the northwestern and southeastern sides of the Kenai lowland. Geochemical similarities, similar glass morphologies, and an absence of opaque phases characterize this layer as a single ash fall and allow correlation. On a regional scale, these correlations concur with previous correlations and show that a shallow anticline with a northwest-southeast-trending axis extends across the Kenai lowland. 28 refs., 14 figs., 1 tab.

  12. Modelling of strata movement with a special reference to caving mechanism in thick seam coal mining

    Energy Technology Data Exchange (ETDEWEB)

    Unver, B.; Yasitli, N.E. [Hacettepe University, Department of Mining Engineering, Beytepe 06532, Ankara (Turkey)

    2006-04-03

    Caving of top coal behind the face is the key factor affecting the efficiency of production at thick coal seams. During production of top coal by caving behind the face not only is a significant amount of coal lost in the goaf but also the coal drawn by means of caving is usually diluted considerably with surrounding rock. Therefore, it is not possible to carry out an efficient production operation unless caving of top coal behind the face is optimized. In this paper, results of 3-D modelling of the top coal caving mechanism at the M3 longwall panel of Omerler Underground Mine located at Tuncbilek (Turkey) are presented by using a finite difference code called FLAC{sup 3D}. According to modelling results, a 1.5-2.0-m-thick layer of coal just above the shield supports is well fractured. However, 3.0-3.5-m-thick layer of coal above the well-fractured part is either not fractured or fractured in the form of large blocks leading to obstruction of windows of shields during coal drawing. It is concluded that, in order to decrease dilution and increase extraction ratio and production efficiency, the top coal should be as uniformly fractured as much as possible. Hence, an efficient and continuous coal flowing behind the face can be maintained. A special pre-fracture blasting strategy just sufficient enough to form cracks in the top coal is suggested by means of comparing results from numerical modelling. (author)

  13. PolyStrata greenhouse gas radiometer for small satellite applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the Phase I program is to demonstrate the potential for our approach and mitigate program risks for future development efforts. To achieve this goal, we...

  14. Breast cancer screening effect across breast density strata: A case-control study.

    Science.gov (United States)

    van der Waal, Daniëlle; Ripping, Theodora M; Verbeek, André L M; Broeders, Mireille J M

    2017-01-01

    Breast cancer screening is known to reduce breast cancer mortality. A high breast density may affect this reduction. We assessed the effect of screening on breast cancer mortality in women with dense and fatty breasts separately. Analyses were performed within the Nijmegen (Dutch) screening programme (1975-2008), which invites women (aged 50-74 years) biennially. Performance measures were determined. Furthermore, a case-control study was performed for women having dense and women having fatty breasts. Breast density was assessed visually with a dichotomized Wolfe scale. Breast density data were available for cases. The prevalence of dense breasts among controls was estimated with age-specific rates from the general population. Sensitivity analyses were performed on these estimates. Screening performance was better in the fatty than in the dense group (sensitivity 75.7% vs 57.8%). The mortality reduction appeared to be smaller for women with dense breasts, with an odds ratio (OR) of 0.87 (95% CI 0.52-1.45) in the dense and 0.59 (95% CI 0.44-0.79) in the fatty group. We can conclude that high density results in lower screening performance and appears to be associated with a smaller mortality reduction. Breast density is thus a likely candidate for risk-stratified screening. More research is needed on the association between density and screening harms. © 2016 UICC.

  15. mmWave PolyStrata(R) High Power Compact Transceiver, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In response to NASA SBIR Topic S1.02 on Microwave Technologies for Remote Sensing, Nuvotronics is pleased to propose a Phase I program focused on delivering an...

  16. Growth in Indigenous and Nonindigenous Chilean Schoolchildren From 3 Poverty Strata

    Science.gov (United States)

    Bustos, Patricia; Amigo, Hugo; Muñoz, Sergio R.; Martorell, Reynaldo

    2001-01-01

    Objectives. This study sought to determine whether the short stature of Mapuche children, an indigenous group in Chile, reflects poverty or genetic heritage and whether the international reference population, derived from studies of US children of mostly European origin, is appropriate for assessing growth failure in indigenous peoples of the Americas. Methods. The study assessed 768 schoolchildren of Mapuche and non-Mapuche ancestry, aged 6 to 9 years, living under conditions of extreme, medium, and low poverty. Results. Growth retardation was strongly related to poverty in both ethnic groups. Within poverty levels, there were no significant differences in stature between ethnic groups, and in low-poverty areas in Santiago, the capital city, mean stature was only slightly less than in the reference population. Conclusions. Poverty, not ancestry, explains the short stature of Mapuche children, and use of the international reference to assess growth in this population is appropriate. PMID:11574328

  17. Prevalence, incidence and progression of lumbar spondylosis by gender and age strata.

    Science.gov (United States)

    Muraki, Shigeyuki; Yoshimura, Noriko; Akune, Toru; Tanaka, Sakae; Takahashi, Ikuno; Fujiwara, Saeko

    2014-07-01

    To identify the prevalence, incidence and progression of radiographic lumbar spondylosis (LS). From the Adult Health Study conducted by the Radiation Effects Research Foundation, 1,204 participants aged 44-85 years who had lumbar spine radiographs in 1990-1992 were reexamined in 1998-2000 (mean 7.9-year interval). The radiographic severity of LS was determined by Kellgren/Lawrenc