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Sample records for carboniferous mountain glaciation

  1. Evolution of Topography in Glaciated Mountain Ranges

    Science.gov (United States)

    Brocklehurst, Simon H.

    2002-01-01

    This thesis examines the response of alpine landscapes to the onset of glaciation. The basic approach is to compare fluvial and glacial laudscapes, since it is the change from the former to the latter that accompanies climatic cooling. This allows a detailed evaluation of hypotheses relating climate change to tectonic processes in glaciated mountain belts. Fieldwork was carried out in the eastern Sierra Nevada, California, and the Sangre de Cristo Range, Colorado, alongside digital elevation model analyses in the western US, the Southern Alps of New Zealand, and the Himalaya of northwestern Pakistan. hypothesis is overstated in its appeal to glacial erosion as a major source of relief production and subsequent peak uplift. Glaciers in the eastern Sierra Nevada and the western Sangre de Cristos have redistributed relief, but have produced only modest relief by enlarging drainage basins at the expense of low-relief topography. Glaciers have lowered valley floors and ridgelines by similar amounts, limiting the amount of "missing mass' that can be generated, and causing a decrease in drainage basin relief. The principal response of glaciated landscapes to rapid rock uplift is the development of towering cirque headwalls. This represents considerable relief production, but is not caused by glacial erosion alone. Large valley glaciers can maintain their low gradient regardless of uplift rate, which supports the "glacial buzzsaw" hypothesis. However, the inability of glaciers to erode steep hillslopes as rapidly can cause mean elevations to rise. Cosmogenic isotope dating is used to show that (i) where plucking is active, the last major glaciation removed sufficient material to reset the cosmogenic clock; and (ii) former glacial valley floors now stranded near the crest of the Sierra Nevada are at varying stages of abandonment, suggesting a cycle of drainage reorganiszation and relief inversion due to glacial erosion similar to that observed in river networks. Glaciated

  2. Sedimentologic and paleoclimatic reconstructions of carbonate factory evolution in the Alborz Basin (northern Iran) indicate a global response to Early Carboniferous (Tournaisian) glaciations

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    Sardar Abadi, Mehrdad; Kulagina, Elena I.; Voeten, Dennis F. A. E.; Boulvain, Frédéric; Da Silva, Anne-Christine

    2017-03-01

    The Lower Carboniferous Mobarak Formation records the development of a storm-sensitive pervasive carbonate factory on the southern Paleo-Tethyan passive margin following the opening of the Paleo-Tethys Ocean into the Alborz Basin along the northern margin of Gondwana. Its depositional facies encompass inner ramp peritidal environments, peloidal to crinoidal shoals, storm to fair-weather influenced mid-ramps, proximal to distal shell beds and low energy outer ramps. Sedimentological analyses and foraminiferal biostratigraphy reveal four events affecting carbonate platform evolution in the Alborz Basin during the Lower Carboniferous: (1) A transgression following global temperature rise in the Early Tournaisian (middle Hastarian) caused the formation of thick-bedded argillaceous limestones. This interval correlates with Early Tournaisian nodular to argillaceous limestones in the Moravia Basin (Lisen Formation, Czech Republic), the Dinant Basin (Pont d'Arcole Formation, Belgium), and at the Rhenish Slate Mountains (Lower Alum shale, Germany). (2) Late Hastarian-early Ivorian glaciations previously identified in Southern Gondwana but had not yet recognized in Northern Gondwana were recorded through a sequence boundary. (3) During the Late Tournaisian-Early Visean?, a differential block faulting regime along the basin's margin caused uplift of the westernmost parts of the Alborz Basin and resulted in subsidence in the eastern part of the central basin. This tectonically controlled shift in depositional regime caused vast sub-aerial exposure and brecciation preserved in the top of the Mobarak Formation in the western portion of the Central Alborz Basin. (4) Tectonic activity coinciding with a progressive, multiphase sea level drop caused indirectly by the Viséan and Serpukhovian glaciations phases ultimately led to the stagnation of the carbonate factory. Paleothermometry proxies, the presence of foraminiferal taxa with a northern Paleo-Tethyan affinity and evidence for

  3. Devonian and Lower Carboniferous Conodonts of the Cantabrian Mountains (Spain) and their stratigraphic application

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    Adrichem Boogaert, van H.A.

    1967-01-01

    A short review of the literature on the stratigraphy of the Devonian and the Lower Carboniferous of the Cantabrian Mountains precedes the report of the author's stratigraphic and palaeontologic observations in León: the Río Esla area (Gedinnian to Viséan), the central Cantabrian area (Famennian to

  4. Ecology of Land Cover Change in Glaciated Tropical Mountains

    Directory of Open Access Journals (Sweden)

    Kenneth R. Young

    2014-12-01

    Full Text Available Tropical mountains contain unique biological diversity, and are subject to many consequences of global climate change, exasperated by concurrent socioeconomic shifts. Glaciers are in a negative mass balance, exposing substrates to primary succession and altering downslope wetlands and streams. A review of recent trends and future predictions suggests a likely reduction in areas of open habitat for species of high mountains due to greater woody plant cover, accompanied by land use shifts by farmers and pastoralists along the environmental gradients of tropical mountains. Research is needed on the biodiversity and ecosystem consequences of successional change, including the direct effects of retreating glaciers and the indirect consequences of combined social and ecological drivers in lower elevations. Areas in the high mountains that are protected for nature conservation or managed collectively by local communities represent opportunities for integrated research and development approaches that may provide ecological spaces for future species range shifts.

  5. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes

    Science.gov (United States)

    Hauer, F. Richard; Locke, Harvey; Dreitz, Victoria; Hebblewhite, Mark; Lowe, Winsor; Muhlfeld, Clint C.; Nelson, Cara; Proctor, Michael F.; Rood, Stewart B.

    2016-01-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologicaltering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth.

  6. Quaternary sediment thickness and bedrock topography of the glaciated United States east of the Rocky Mountains

    Science.gov (United States)

    Soller, David R.; Garrity, Christopher P.

    2018-01-26

    Beginning roughly 2.6 million years ago, global climate entered a cooling phase known as the Pleistocene Epoch. As snow in northern latitudes compacted into ice several kilometers thick, it flowed as glaciers southward across the North American continent. These glaciers extended across the northern United States, dramatically altering the landscape they covered. East of the Rocky Mountains, the ice coalesced into continental glaciers (called the Laurentide Ice Sheet) that at times blanketed much of the north-central and northeastern United States. To the west of the Laurentide Ice Sheet, glaciers formed in the mountains of western Canada and the United States and coalesced into the Cordilleran ice sheet; this relatively smaller ice mass extended into the conterminous United States in the northernmost areas of western Montana, Idaho, and Washington. Throughout the Pleistocene, landscape alteration occurred by (1) glacial erosion of the rocks and sediments; (2) redeposition of the eroded earth materials in a form substantially different from their source rocks, in terms of texture and overall character; and (3) disruption of preexisting drainage patterns by the newly deposited sediments. In many cases, pre-glacial drainage systems (including, for example, the Mississippi River) were rerouted because their older drainage courses became blocked with glacial sediment.The continental glaciers advanced and retreated many times across those areas. During each ice advance, or glaciation, erosion and deposition occurred, and the landscape was again altered. Through successive glaciations, the landscape and the bedrock surface gradually came to resemble their present configurations. As continental ice sheets receded and the Pleistocene ended, erosion and deposition of sediment (for example in stream valleys) continued to shape the landscape up to the present day (albeit to a lesser extent than during glaciation). The interval of time since the last recession of the glaciers

  7. Melo carboniferous basin

    International Nuclear Information System (INIS)

    Flossdarf, A.

    1988-01-01

    This report is about of the Melo carboniferous basin which limits are: in the South the large and high Tupambae hill, in the west the Paraiso hill and the river mountains, in the North Yaguaron river basin to Candidata in Rio Grande del Sur in Brazil.

  8. Conodont biostratigraphy and depositional history of the Middle Devonian to Lower Carboniferous in the Cantabrian zone (Cantabrian Mountains, Spain)

    NARCIS (Netherlands)

    Raven, J.G.M.

    1983-01-01

    Within the Cantabrian zone during the Devonian and Early Carboniferous three large palaeogeographical units were of importance: the Asturian geanticline, the Palencian basin and the Asturo-Leonesian basin. These units have a different history of sedimentation, particularly the Palencian basin.

  9. Surface Hydrological Processes of Rock Glaciated Basins in the San Juan Mountains, Colorado

    Science.gov (United States)

    Mateo, E. I.

    2017-12-01

    Glaciers in the western United States have been examined in terms of their summer meltwater contributions to regional hydrological systems. In the San Juan Mountains of Colorado where glaciers do not and cannot exist due to a rising zero-degree isotherm, rock glaciers take the place of valley glaciers during the summer runoff period. Most of the rock glaciers in Colorado are located on a northerly slope aspect, however, there are multiple in the southwest region of the state that occur on different aspects. This study asked how slope aspect and rising air temperatures influenced the hydrological processes of streams below rock glaciers in the San Juan Mountains during the 2016 summer season. This project focused on three basins, Yankee Boy basin, Blue Lakes basin, and Mill Creek basin, which are adjacent to each other and share a common peak, Gilpin Peak. Findings of this one-season study showed that air temperature significantly influenced stream discharge below each rock glacier. Discharge and air temperature patterns indicate a possible air temperature threshold during late summer when rock glacier melt increased at a greater rate. The results also suggest that slope aspect of rock glacier basins influences stream discharge, but temperature and precipitation are likely larger components of the melt regimes. The continuation of data collection during the 2017 summer season has allowed for more detailed analysis of the relationship between air temperature and rock glacier melt. This continual expansion of the original dataset is crucial for understanding the hydrological processes of surface runoff below rock glaciers.

  10. Numerical modeling of the Snowmass Creek paleoglacier, Colorado, and climate in the Rocky Mountains during the Bull Lake glaciation (MIS 6)

    Energy Technology Data Exchange (ETDEWEB)

    Eric M. Leonard; Mitchell A. Plummer; Paul E. Carrara

    2014-04-01

    Well-preserved moraines from the penultimate, or Bull Lake, glaciation of Snowmass Creek Valley in the Elk Range of Colorado present an opportunity to examine the character of the high-altitude climate in the Rocky Mountains during Marine Oxygen Isotope Stage 6. This study employs a 2-D coupled mass/energy balance and flow model to assess the magnitudes of temperature and precipitation change that could have sustained the glacier in mass-balance equilibrium at its maximum extent during the Bull Lake glaciation. Variable substrate effects on glacier flow and ice thickness make the modeling somewhat more complex than in geologically simpler settings. Model results indicate that a temperature depression of about 6.7°C compared with the present (1971–2000 AD) would have been necessary to sustain the Snowmass Creek glacier in mass-balance equilibrium during the Bull Lake glaciation, assuming no change in precipitation amount or seasonality. A 50% increase or decrease from modern precipitation would have been coupled with 5.2°C and 9.1°C Bull Lake temperature depressions respectively. Uncertainty in these modeled temperature depressions is about 1°C.

  11. The MIS 3 maximum of the Torres del Paine and Última Esperanza ice lobes in Patagonia and the pacing of southern mountain glaciation

    Science.gov (United States)

    García, Juan-Luis; Hein, Andrew S.; Binnie, Steven A.; Gómez, Gabriel A.; González, Mauricio A.; Dunai, Tibor J.

    2018-04-01

    The timing, structure and termination of the last southern mountain glaciation and its forcing remains unclear. Most studies have focused on the global Last Glacial Maximum (LGM; 26.5-19 ka) time period, which is just part of the extensive time-frame within the last glacial period, including Marine Isotope Stages 3 and 4. Understanding the glacial fluctuations throughout the glacial period is a prerequisite for uncovering the cause and climate mechanism driving southern glaciation and the interhemispheric linkages of climate change. Here, we present an extensive (n = 65) cosmogenic 10Be glacier chronology derived from moraine belts marking the pre-global LGM extent of the former Patagonian Ice Sheet in southernmost South America. Our results show the mountain ice sheet reached its maximum extent at 48.0 ± 1.8 ka during the local LGM, but attained just half this extent at 21.5 ± 1.8 ka during the global LGM. This finding, supported by nearby glacier chronologies, indicates that at orbital time scales, the southern mid-latitude glaciers fluctuated out-of-phase with northern hemisphere ice sheets. At millennial time-scales, our data suggest that Patagonian and New Zealand glaciers advanced in unison with cold Antarctic stadials and reductions in Southern Ocean sea surface temperatures. This implies a southern middle latitudes-wide millennial rhythm of climate change throughout the last glacial period linked to the north Atlantic by the bipolar seesaw. We suggest that winter insolation, acting alongside other drivers such as the strength and/or position of the southern westerlies, controlled the extents of major southern mountain glaciers such as those in southernmost South America.

  12. The Chinese North Tianshan Orogen was a rear-arc (or back-arc) environment in the Late Carboniferous: constraint from the volcanic rocks in the Bogda Mountains

    Science.gov (United States)

    Xie, W.

    2017-12-01

    The Tianshan Orogen is a key area for understanding the Paleozoic tectonics and long-lasting evolution of the Central Asian Orogenic Belt (CAOB). However, considerable debate persists as to its tectonic setting during the late Paleozoic, with active subduction system and intraplate large igneous provinces as two dominant schools (Ma et al., 1997; Gu et al., 2000; Xiao et al., 2004; Han et al., 2010; Shu et al., 2011; Chen et al., 2011; Xia et al., 2012). With aims of providing constraints on this issue, petrology, mineralogy, geochronological and geochemistry for the Late Carboniferous volcanics from the Bogda Mountains have been carried out. We find two suits of high-Al basalt (HAB, 315-319 Ma) and a suit of submarine pillow basalt ( 311 Ma) in this region. Both of the two basalts belong to the tholeiitic magma (the tholeiitic index THI > 1) and contain low pre-eruptive magmatic H2O (coexisted with the Bogda HABs is I-type intermediate ignimbrites and rhyolite lavas. The rhyolites are formed by partial melting of a hydrated and juvenile arc crust and the ignimbrites are affected by magma mingling and feldspar fractionation (Xie et al., 2016c). The two basalts both have the MORB-like Sr-Nd-Hf-Pb isotopes and arc-like trace element compositions. We discuss that they may have been generated from a dry and depleted mantle source metasomatized by coexisted felsic volcanics were likely formed in a rear-arc or back-arc environment, probably related to southward subduction of the Paleo-Tianshan Ocean (Xie et al., 2016a, b, c).

  13. Climate along the crest of the US Rocky Mountains during the last glaciation: preliminary insights from numerical modeling of paleoglaciers

    Science.gov (United States)

    Leonard, E. M.; Laabs, B. J.; Plummer, M. A.; Huss, E.; Spiess, V. M.; Mackall, B. T.; Jacobsen, R. E.; Quirk, B.

    2012-12-01

    Climate conditions at the time of the local Last Glacial Maximum (LGM) in the US Rocky Mountains were assessed using a 2-d coupled glacier energy/mass-balance and ice-flow model (Plummer and Phillips, 2003). The model was employed to understand the conditions that would be necessary to sustain valley glaciers and small mountain icecaps at their maximum extents in eight areas distributed along the crest of the range from northern New Mexico (35.8oN) to northern Montana (48.6oN). For each setting, model experiments yield a set of temperature and precipitation combinations that may have accompanied the local LGM. If the results of global and regional climate models are used to constrain temperature depression estimates from our model experiments, the following precipitation pattern emerges for the local LGM. In the northern Rocky Mountains in Montana and northern Wyoming, model results suggest a strong reduction in precipitation of 50% or more. In the central Rocky Mountains of southern Wyoming and Colorado, precipitation appears to have been 50-90% of modern. By contrast, precipitation appears to have been strongly enhanced in the southern Rocky Mountains of New Mexico. These results are broadly consistent with a pattern of precipitation observed in global and regional climate simulations of the LGM in the western U.S., in which precipitation was reduced in the northern Rocky Mountains but increased in the southern Rocky Mountains. This pattern may reflect a southward displacement of mean position the Pacific Jet Stream in western North America during and possibly following the LGM.

  14. Increasing risks related to landslides from degrading permafrost into new lakes in de-glaciating mountain ranges

    Science.gov (United States)

    Haeberli, Wilfried; Schaub, Yvonne; Huggel, Christian

    2017-09-01

    While glacier volumes in most cold mountain ranges rapidly decrease due to continued global warming, degradation of permafrost at altitudes above and below glaciers is much slower. As a consequence, many still existing glacier and permafrost landscapes probably transform within decades into new landscapes of bare bedrock, loose debris, sparse vegetation, numerous new lakes and steep slopes with slowly degrading permafrost. These new landscapes are likely to persist for centuries if not millennia to come. During variable but mostly extended future time periods, such new landscapes will be characterized by pronounced disequilibria within their geo- and ecosystems. This especially involves long-term stability reduction of steep/icy mountain slopes as a slow and delayed reaction to stress redistribution following de-buttressing by vanishing glaciers and to changes in mechanical strength and hydraulic permeability caused by permafrost degradation. Thereby, the probability of far-reaching flood waves from large mass movements into lakes systematically increases with the formation of many new lakes and systems of lakes in close neighborhood to, or even directly at the foot of, so-affected slopes. Results of recent studies in the Swiss Alps are reviewed and complemented with examples from the Cordillera Blanca in Peru and the Mount Everest region in Nepal. Hot spots of future hazards from potential flood waves caused by large rock falls into new lakes can already now be recognized. To this end, integrated spatial information on glacier/permafrost evolution and lake formation can be used together with scenario-based models for rapid mass movements, impact waves and flood propagation. The resulting information must then be combined with exposure and vulnerability considerations related to settlements and infrastructure. This enables timely planning of risk reduction options. Such risk reduction options consist of two components: Mitigation of hazards, which in the present

  15. The rise and fall of the mountain hare (Lepus timidus) during Pleistocene glaciations: expansion and retreat with hybridization in the Iberian Peninsula.

    Science.gov (United States)

    Melo-Ferreira, J; Boursot, P; Randi, E; Kryukov, A; Suchentrunk, F; Ferrand, N; Alves, P C

    2007-02-01

    The climatic fluctuations during glaciations have affected differently arctic and temperate species. In the northern hemisphere, cooling periods induced the expansion of many arctic species to the south, while temperate species were forced to retract in southern refugia. Consequently, in some areas the alternation of these species set the conditions for competition and eventually hybridization. Hares in the Iberian Peninsula appear to illustrate this phenomenon. Populations of Iberian hare (Lepus granatensis), brown hare (Lepus europaeus) and broom hare (Lepus castroviejoi) in Northern Iberia harbour mitochondrial haplotypes from the mountain hare (Lepus timidus), a mainly boreal and arctic species presently absent from the peninsula. To understand the history of this past introgression we analysed sequence variation and geographical distribution of mitochondrial control region and cytochrome b haplotypes of L. timidus origin found in 378 specimens of these four species. Among 124 L. timidus from the Northern Palaearctic and the Alps we found substantial nucleotide diversity (2.3%) but little differentiation between populations. Based on the mismatch distribution of the L. timidus sequences, this could result from an expansion at a time of temperature decrease favourable to this arctic species. The nucleotide diversity of L. timidus mtDNA found in Iberian L. granatensis, L. europaeus and L. castroviejoi (183, 70 and 1 specimens, respectively) was of the same order as that in L. timidus over its range (1.9%), suggesting repeated introgression of multiple lineages. The structure of the coalescent of L. granatensis sequences indicates that hybridization with L. timidus was followed by expansion of the introgressed haplotypes, as expected during a replacement with competition, and occurred when temperatures started to rise, favouring the temperate species. Whether a similar scenario explains the introgression into Iberian L. europaeus remains unclear but it is possible

  16. 10Be exposure age chronology of the last glaciation of the Roháčská Valley in the Western Tatra Mountains, central Europe

    Science.gov (United States)

    Engel, Zbyněk; Mentlík, Pavel; Braucher, Régis; Křížek, Marek; Pluháčková, Markéta; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Keddadouche, Karim; Aster Team; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Keddadouche, Karim

    2017-09-01

    10Be exposure ages from moraines and bedrock sites in the Roháčská Valley provide chronology of the last glaciation in the largest valley of the Western Tatra Mts., the Western Carpathians. The minimum apparent exposure age of 19.4 ± 2.1 ka obtained for the oldest sampled boulder and the mean age of 18.0 ± 0.8 ka calculated for the terminal moraine indicate that the oldest preserved moraine was probably deposited at the time of the global Last Glacial Maximum (LGM). The age of this moraine coincides with the termination of the maximum glacier expansion in other central European ranges, including the adjacent High Tatra Mts. and the Alps. The equilibrium line altitude (ELA) of the LGM glacier in the Roháčská Valley, estimated at 1400-1410 m a.s.l., was 50-80 m lower than in the eastern part of the range, indicating a positive ELA gradient from west to east among the north-facing glaciers in the Tatra Mts. Lateglacial glacier expansion occurred no later than 13.4 ± 0.5 ka and 11.9 ± 0.5 ka, as indicated by the mean exposure ages calculated for re-advance moraines. This timing is consistent with the exposure age chronology of the last Lateglacial re-advance in the High Tatra Mts., Alps and lower mountain ranges in central Europe. The ELA in the Roháčská Valley estimated at 1690-1770 m a.s.l. in this period was located 130-300 m lower than in the north-facing valleys in the High Tatra Mts. 10Be exposure ages obtained for a rock glacier constrains the timing of this landform stabilization in the Salatínska Valley and provides the first chronological evidence for the Lateglacial activity of rock glaciers in the Carpathians.

  17. Depositional environments and cyclo- and chronostratigraphy of uppermost Carboniferous-Lower Triassic -lacustrine deposits, southern Bogda Mountains, NW China - A terrestrfluvialial paleoclimatic record of mid-latitude NE Pangea

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    Yang, W.; Feng, Q.; Liu, Yajing; Tabor, N.; Miggins, D.; Crowley, J.L.; Lin, J.; Thomas, S.

    2010-01-01

    Two uppermost Carboniferous–Lower Triassic fluvial–lacustrine sections in the Tarlong–Taodonggou half-graben, southern Bogda Mountains, NW China, comprise a 1834 m-thick, relatively complete sedimentary and paleoclimatic record of the east coast of mid-latitude NE Pangea. Depositional environmental interpretations identified three orders (high, intermediate, and low) of sedimentary cycles. High-order cycles (HCs) have five basic types, including fluvial cycles recording repetitive changes of erosion and deposition and lacustrine cycles recording repetitive environmental changes associated with lake expansion and contraction. HCs are grouped into intermediate-order cycles (ICs) on the basis of systematic changes of thickness, type, and component lithofacies of HCs. Nine low-order cycles (LCs) are demarcated by graben-wide surfaces across which significant long-term environmental changes occurred. A preliminary cyclostratigraphic framework provides a foundation for future studies of terrestrial climate, tectonics, and paleontology in mid-latitude NE Pangea.Climate variabilities at the intra-HC, HC, IC, and LC scales were interpreted from sedimentary and paleosol evidence. Four prominent climatic shifts are present: 1) from the humid–subhumid to highly-variable subhumid–semiarid conditions at the beginning of Sakamarian; 2) from highly-variable subhumid–semiarid to humid–subhumid conditions across the Artinskian-Capitanian unconformity; 3) from humid–subhumid to highly-variable subhumid–semiarid conditions at early Induan; and 4) from the highly-variable subhumid–semiarid to humid–subhumid conditions across the Olenekian-Anisian unconformity. The stable humid–subhumid condition from Lopingian to early Induan implies that paleoclimate change may not have been the cause of the end-Permian terrestrial mass extinction. A close documentation of the pace and timing of the extinction and exploration of other causes are needed. In addition, the

  18. Conodont-bearing formations of Devonian and Lower Carboniferous age in northern León and Palencia (Spain)

    NARCIS (Netherlands)

    Adrichem Boogaert, van H.A.

    1965-01-01

    Conodonts have been extracted from calcareous units of the Devonian and Lower Carboniferous sequence from 3 areas in the S. part of the Cantabrian Mountains. There can be distinguished Emsian, Givetian, Frasnian, Famennian and Viséan faunas.

  19. The Shale Gas potential of Lower Carboniferous Sediments in Germany

    Science.gov (United States)

    Kerschke, D.; Mihailovic, A.; Schulz, H., -M.; Horsfield, B.

    2012-04-01

    Organic-rich Carboniferous sediments are proven source rocks for conventional gas systems in NW Europe and are likely gas shale candidates. Within the framework of GeoEnergie, an initiative to strengthen scientific excellence, funded by the German Ministry of Education and Research (BMBF), the influence of palaeogeography and basin dynamics on sedimentology and diagenesis is being investigated. Our aim is to unravel the evolution of shale gas-relevant properties which control gas prospectivity and production parameters like porosity, brittleness, etc. for the Lower Carboniferous in Germany. Northern Germany is underlain by thick, mudstone-bearing Carboniferous successions with a wide range of thermal maturities. Some of these mudstone horizons are rich in organic carbon which is either of marine and/or terrigenous origin. During the Carboniferous deposition of fine-grained, TOC-rich basinal sediments changed into shallow marine to paralic siliciclastic sediments (carbonates during the Lower Carboniferous) in the north, and grade into coarse-grained sediments close to the uprising Variscan mountains in the south. As a result different architectural elements including TOC-rich fine-grained sediments like basinal shales, fine-grained parts of turbidites, and shallow marine mudstones occur in both the Lower and the Upper Carboniferous section. A high shale gas potential occurs in basinal shales of Namurian age with marine organic material and TOC contents of up to 8 % (Rhenish Alum Shales). Such sediments with thermal maturities between 1.3 to 3.0 % vitrinite reflectance and sufficient quartz contents occur in wide areas of present-day Central European Basins System (CEBS), and are at favourable depth for shale gas exploration predominantly along the southern CEBS margin.

  20. Future glaciation in Fennoscandia

    Energy Technology Data Exchange (ETDEWEB)

    Forsstroem, L. [Oulu Univ. (Finland). Dept. of Geosciences

    1999-09-01

    Cyclic growing and melting of great ice sheets in the Northern Hemisphere is typical for the Quaternary Period, and it is likely that this cycle will continue in the future. This report discusses the principal processes predicted to occur during the future glaciation which are likely to be of importance for a nuclear waste repository. It is a revised version of a synthesis of the results of two state-of-the art reports, working meetings and a seminar. Based on present knowledge, two alternative trends (A and B) can be presented for fluctuations in climate in Fennoscandia. According to forecast A the climate will gradually become colder, permitting the growth of glaciers in the mountainous areas of Norway and Sweden after 5000 years. After a minor warmer period, a greater ice advance will cover a large part of Finland around 20 000 years from now. After a new minor interstade, the ice will advance again, so that c. 60 000 years from now the Stockholm-Helsinki region will be covered by thick ice. The ice sheet will melt partially at 70 000 years AP, but then it will grow to its maximum around 100 000 years AP and cover the whole Baltic basin. Almost complete melting of the ice sheet will take place during the next interglaciation c. 120 coo years AP. According to forecast B the growth of the ice sheet will not begin for another 50 000 years, and Finland will be covered by ice about 60 000 years from now. After a minor melting, the ice sheet will enlarge and cover almost the whole Baltic basin 100 000 years from now. During the following ice minimum, at 120 000 years AP, the ice sheet will still cover northern Finland. At 150 000 years it will cover the whole Baltic basin, but then it will melt almost completely by 165 000 years from now, during the following interglaciation. In both forecasts the main changes caused by the ice sheet will be downwarping/uplift of the crust and changes in sea level. In addition, changes in the groundwater head and flux are foreseen

  1. Tectonic controls of Holocene erosion in a glaciated orogen

    OpenAIRE

    Adams, Byron A.; Ehlers, Todd A.

    2018-01-01

    Recent work has highlighted a strong, worldwide, glacial impact of orogen erosion rates over the last 2 Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen, the Olympic Mountains, USA. We present 14 new 10Be and ...

  2. Sledovi pleistocenske poledenitve Stare Galičice, Makedonija = Remmants of Pleistocene glaciation on Stara Galičica Mountain, Macedonia

    Directory of Open Access Journals (Sweden)

    Uroš Stepišnik

    2012-01-01

    Full Text Available The Stara Galičica Mountain was highly reshaped by glacial processes during the Pleistocene.Based on the detailed morphographical mapping of glacial features, the extent ofglaciation was determined as being far larger than described in previous references. The innerpart of the massif was covered with an ice-cap from where outlet glaciers were flowingout. On the basis of morphometrical analysis of glacial features, the altitude of the glacierequilibrium line during the Last Glacial Maximum was established at 1840 m a.s.l.

  3. New lakes in de-glaciating high-mountain regions - a challenge for integrative research about hazard protection and sustainable use

    Science.gov (United States)

    Haeberli, W.

    2012-12-01

    As a consequence of rapid glacier vanishing, an increasing number of smaller and larger lakes are forming in high-mountain regions worldwide. Such new lakes can be touristic landscape attractions and may also represent interesting potentials for hydropower production. However, they more and more often come into existence at the foot of very large and steep icy mountain walls, which are progressively destabilizing due to changing surface and subsurface ice conditions. The probability of far-reaching flood and debris flow catastrophes caused by impact waves from large rock/ice avalanches into lakes may still appear to be small now but steadily increases for long time periods to come. Corresponding projects related to hazard protection and sustainable use should be combined in an integrative and participatory planning process. This planning process must start soon, because the development in nature is fast and most likely accelerating. Technical tools for creating the necessary scientific knowledge basis at local to regional scales exist and can be used. The location of future new lakes in topographic bed depressions of now still glacier-covered areas can be quite safely assessed on the basis of morphological criteria or by applying ice thickness estimates using digital terrain information. Models for ice-thickness estimates couple the depth to bedrock via the basal shear stress with the surface slope and provide a (relative) bed topography which is much more robust than the (absolute) value of the calculated ice thickness. Numerical models at various levels of sophistication can be used to simulate possible future glacier changes in order to establish the probable time of lake formation and the effects of glacier shrinking on runoff seasonality and water supply. The largest uncertainties thereby relate to the large uncertainties of (absolute) ice thickness and mass/energy fluxes at the surface (climate scenarios, precipitation and albedo changes, etc.). Combined

  4. Differential effects of historical migration, glaciations and human impact on the genetic structure and diversity of the mountain pasture weed Veratrum album L

    DEFF Research Database (Denmark)

    Treier, Urs; Müller-Schärer, H.

    2011-01-01

    Aim  Today’s genetic population structure and diversity of species can be understood as the result of range expansion from the area of origin, past climatic oscillations and contemporary processes. We examined the relative importance of these factors in Veratrum album L., a toxic weed of mountain...... grasslands. Location  Continental Europe. Methods  Forty populations from the Asian border (Urals and Caucasus) to Portugal were studied using amplified fragment length polymorphisms (AFLPs) combined with selected plant and population measures. The data were analysed with phylogenetic, population genetic...... and regression methods inferring both genetic structure and diversity from geographic and ecological factors. Results  Fragment frequency clines together with genetic distance clustering and principal coordinates analysis indicated an east–west direction in the genetic structure of V. album, suggesting ancient...

  5. Ancient glaciations and hydrocarbon accumulations in North Africa and the Middle East

    Science.gov (United States)

    Le Heron, Daniel Paul; Craig, Jonathan; Etienne, James L.

    2009-04-01

    At least six glaciations are purported to have affected North Africa and the Middle East region over the last one billion years, including two in the Cryogenian (Neoproterozoic), Hirnantian (Late Ordovician), Silurian, Carboniferous and Early Permian events. The sedimentary record associated with these glaciations, together with the intensity to which each has been investigated, is highly variable. As hydrocarbon exploration proceeds aggressively across the North Africa and Middle East regions, we review the relationship between glaciation and hydrocarbon accumulations. With the exception of Oman, and locally Egypt, which were tectonically active both during the Neoproterozoic and Early Palaeozoic all glaciations took place along an essentially stable passive continental margin. During the Neoproterozoic, two glaciations are recognised, referred to as older and younger Cryogenian glaciations respectively. Both of these Cryogenian events are preserved in Oman; only the younger Cryogenian has been reported in North Africa in Mauritania and Mali at the flanks of the Taoudenni Basin. The process of initial deglaciation in younger Cryogenian glaciations resulted in incision, at least locally producing large-bedrock palaeovalleys in Oman, and the deposition of glacial diamictites, gravels, sandstones and mudstones. As deglaciation progressed "cap carbonates" were deposited, passing vertically into shale with evidence for deposition in an anoxic environment. Hence, younger Cryogenian deglaciation may be associated with hydrocarbon source rock deposits. Hirnantian (Late Ordovician) glaciation was short lived (economic significance across central North Africa. Therefore, an appreciation of the processes of ice sheet growth and decay provides significant insights into the controls on large-scale heterogeneities within these sediments, and in analogue deposits produced by glaciations of different ages. Deglacial, Early Silurian black shale represents the most important

  6. Mountains

    Science.gov (United States)

    Regina M. Rochefort; Laurie L. Kurth; Tara W. Carolin; Robert R. Mierendorf; Kimberly Frappier; David L. Steenson

    2006-01-01

    This chapter concentrates on subalpine parklands and alpine meadows of southern British Columbia, Washington, Oregon, and western Montana. These areas lie on the flanks of several mountain ranges including the Olympics, the Cascades of Oregon and Washington, and the Coast Mountains in British Columbia.

  7. Late Pleistocene glaciation of the Mt Giluwe volcano, Papua New Guinea

    Science.gov (United States)

    Barrows, T.T.; Hope, G.S.; Prentice, M.L.; Fifield, L.K.; Tims, S.G.

    2011-01-01

    The Mt Giluwe shield volcano was the largest area glaciated in Papua New Guinea during the Pleistocene. Despite minimal cooling of the sea surface during the last glacial maximum, glaciers reached elevations as low as 3200 m. To investigate changes in the extent of ice through time we have re-mapped evidence for glaciation on the southwest flank of Mt Giluwe. We find that an ice cap has formed on the flanks of the mountain on at least three, and probably four, separate occasions. To constrain the ages of these glaciations we present 39 new cosmogenic 36Cl exposure ages complemented by new radiocarbon dates. Direct dating of the moraines identifies that the maximum extent of glaciation on the mountain was not during the last glacial maximum as previously thought. In conjunction with existing potassium/argon and radiocarbon dating, we recognise four distinct glacial periods between 293-306 ka (Gogon Glaciation), 136-158 ka (Mengane Glaciation), centred at 62 ka (Komia Glaciation) and from >20.3-11.5 ka (Tongo Glaciation). The temperature difference relative to the present during the Tongo Glaciation is likely to be of the order of at least 5 ??C which is a minimum difference for the previous glaciations. During the Tongo Glaciation, ice was briefly at its maximum for less than 1000 years, but stayed near maximum levels for nearly 4000 years, until about 15.4 ka. Over the next 4000 years there was more rapid retreat with ice free conditions by the early Holocene. ?? 2011 Elsevier Ltd.

  8. The Glaciation of the Ecuadorian Andes

    Science.gov (United States)

    Schubert, Carlos

    This pleasing book fills the gap in the knowledge about Pleistocene and recent glaciation between Colombia and Peru. A significant amount of data exists already for Colombia and Venezuela and for Peru, Bolivia, and, particularly, Chile. Hastenrath has now given us a description of glaciers and glaciation underneath the equator in the Andes.The book begins with brief summaries of the physiography and the atmospheric circulation, which give the general setting of Ecuador. Then follow detailed descriptions of the glaciers and glacial morphology of all the important mountains of the Western and Eastern Cordilleras. These are well illustrated, and a particularly useful feature is the comparison of old photographs and paintings of glaciers with modern photographs, many taken by the author. All illustrate the spectacular retreat of the glaciers in the Ecuadorian Andes during the last century and correlate quite well with observations elsewhere. This retreat is snown quantitatively in Table 4, in terms of decrease in glacier-covered area since the glacial advance of moraine stage III. The area of present-day glaciers is about 10% of the area during that stage (compared with about 1.5% in the Sierra Nevada de Mérida, Venezuela). A series of maps show the glacial morphology of the mountains (unfortunately, some of the maps have been included within the binding, thus losing some information; they could have been reduced somewhat to fit a single page or, if too large, could have been included in the pocket, together with the map of Chimborazo-Carihuairazo).

  9. CARBONIFEROUS CORALS AND CHAETETIDS FROM EXOTIC LIMESTONE BLOCK OF THE CRIMEA

    OpenAIRE

    OGAR, VICTOR; KLEVTSOVSKYI, ANDREY

    2015-01-01

    A chaetetid sponge and coral fauna from a Carboniferous exotic limestone block in the Lower Jurassic Esciorda olistostrome on the Bodrak River (Crimean Mountains) are described for the first time. The Bodrak exotic block is composed of massive limestone. It contains the chaetetid Chaetetes (Boswellia) sp., the tabulate coral Multithecopora sp., and poorly preserved rugose corals, including Dibunophyllum? sp., Cordibia? sp. and gen. et sp. indet. Only the fasciculate colonies of the rugose cor...

  10. The Carboniferous of the Western Karakoram (Pakistan)

    Science.gov (United States)

    Gaetani, M.; Zanchi, A.; Angiolini, L.; Olivini, G.; Sciunnach, D.; Brunton, H.; Nicora, A.; Mawson, R.

    2004-05-01

    The results of the study of the Carboniferous successions in the western part of the Northern Karakoram during three geological expeditions are summarized here. Rocks of that period are not uniformly preserved in the several thrust sheets forming the Northern Karakoram. In most of them only the basal part of the Carboniferous, up to the Visean, is preserved, whilst in the Karambar thrust sheet a more complete section—previously almost unknown—is preserved. Four new lithostratigraphic units, time-constrained by brachiopod and conodont biostratigraphy, are described, from bottom to top: (1) the Margach Formation: prevailing dark shales with subordinate fine subarkoses and quartzarenites, up to 300 m thick (mid-Famennian to middle Tournaisian); (2) the Ribat Formation: grey crinoidal limestones passing upwards to dark marly limestones and marls, at least 300 m thick (middle Tournaisian to Serpukhovian); (3) the Lupsuk Formation: subarkoses to feldspathic quartzarenites in thick beds, alternating with dark shales and siltstones, up to 400 m thick (Serpukhovian to uppermost Carboniferous); (4) within the Lupsuk Formation a local member, the Twin Valleys Member, up to 100 m thick, a bioclastic limestone intercalation of post-Moscovian age, is distinguished. The Carboniferous successions are invariably sealed by the arkoses to quartzarenites of the Gircha Formation, 133 m above the base of which, in the Karambar area, an Asselian brachiopod fauna was recovered. The Carboniferous succession is interpreted as recording the evolution of the passive margin of the Northern Karakoram Terrane, from early rifting stage in the Late Devonian to syn-rift events during the Late Carboniferous. The basal part of the Gircha Formation, of latest Carboniferous-earliest Permian age, is considered to have been deposited above a break-up unconformity, linked to the early drifting in the seaway bordering the Karakoram. In the palaeontological appendix the most significant brachiopod taxa

  11. Asynchronous glaciations in arid continental climate

    Science.gov (United States)

    Batbaatar, Jigjidsurengiin; Gillespie, Alan R.; Fink, David; Matmon, Ari; Fujioka, Toshiyuki

    2018-02-01

    Mountain glaciers at ∼26-19 ka, during the global Last Glacial Maximum near the end of the last 105 yr glacial cycle, are commonly considered on the basis of dating and field mapping in several well-studied areas to have been the largest of the late Quaternary and to have advanced synchronously from region to region. However, a numerical sensitivity model (Rupper and Roe, 2008) predicts that the fraction of ablation due to melting varies across Central Asia in proportion to the annual precipitation. The equilibrium-line altitude of glaciers across this region likely varies accordingly: in high altitude, cold and arid regions sublimation can ablate most of the ice, whereas glaciers fed by high precipitation cannot ablate completely due to sublimation alone, but extend downhill until higher temperatures there cause them to melt. We have conducted field studies and 10Be dating at five glaciated sites along a precipitation gradient in Mongolia to test the Rupper/Roe model. The sites are located in nearby 1.875 × 1.875° cells of the Rupper/Roe model, each with a different melt fraction, in this little-studied region. The modern environment of the sites ranges from dry subhumid in the north (47.7° N) to arid in the south (45° N). Our findings show that the maximum local advances in the dry subhumid conditions predated the global Last Glacial Maximum and were likely from MIS 3. However, we also found that at ∼8-7 ka a cirque glacier in one mountain range of the arid Gobi desert grew to a magnitude comparable to that of the local maximum extent. This Holocene maximum occurred during a regional pluvial period thousands of years after the retreat of the Pleistocene glaciers globally. This asynchronous behavior is not predicted by the prevailing and generally correct presumption that glacier advances are dominantly driven by temperature, although precipitation also plays a role. Our findings are consistent with and support the Rupper/Roe model, which calls for

  12. Aridification across the Carboniferous-Permian transition in central equatorial Pangea: The Catalan Pyrenean succession (NE Iberian Peninsula)

    Science.gov (United States)

    Mujal, Eudald; Fortuny, Josep; Marmi, Josep; Dinarès-Turell, Jaume; Bolet, Arnau; Oms, Oriol

    2018-01-01

    The Carboniferous-Permian terrestrial successions record a global climatic shift from icehouse to hothouse conditions. Our multidisciplinary study documents an aridification trend throughout the 1000 m thick composite terrestrial succession of the western Catalan Pyrenees (NE Iberian Peninsula), representing this time period. The detailed stratigraphic framework integrates sedimentology, paleopedology, biochronology (plant fossils and tetrapod footprints) and geochronology (paleomagnetism). Additional absolute age correlation is also carried out. The new and reviewed data show that the late Carboniferous wet environments (with short drought periods) progressively changed to a strong seasonal semi-arid and arid climate (with short humid periods) through the early Permian. This paleoclimatic trend supports the previously suggested aridification of the Pangean pan-tropical belt, and supports the hypothesis of the influence of the recurrent climatic fluctuations in Central Pangea, being tentatively correlated to the Southern Gondwanan glaciation-deglaciation periods. Therefore, the Carboniferous-Permian terrestrial succession from the Catalan Pyrenees emerges as a continuous record that can help to constrain late Paleozoic paleoenvironmental events.

  13. CARBONIFEROUS CORALS AND CHAETETIDS FROM EXOTIC LIMESTONE BLOCK OF THE CRIMEA

    Directory of Open Access Journals (Sweden)

    VICTOR OGAR

    2015-11-01

    Full Text Available A chaetetid sponge and coral fauna from a Carboniferous exotic limestone block in the Lower Jurassic Esciorda olistostrome on the Bodrak River (Crimean Mountains are described for the first time. The Bodrak exotic block is composed of massive limestone. It contains the chaetetid Chaetetes (Boswellia sp., the tabulate coral Multithecopora sp., and poorly preserved rugose corals, including Dibunophyllum? sp., Cordibia? sp. and gen. et sp. indet. Only the fasciculate colonies of the rugose coral Lytvophyllum askynensis (Kossovaya, 2009 are confidently identified. The studied association of fossils is similar to that of the Donets Basin and the Urals and confirms the Lower Bashkirian age of the Bodrak limestone block. 

  14. Cosmic Reason of Great Glaciation

    Science.gov (United States)

    Bagrov, Alexander; Murtazov, Andrey

    The origin of long-time and global glaciations in the past of our planet, which have been named «great», is still not clear. Both the advance of glaciers and their subsequent melting must be connected with some energy consuming processes. There is a powerful energy source permanently functioning throughout the Earth’s history - the solar radiation. The equality of the incoming shortwave solar energy and the transformed long-wave energy emitted by the Earth provides for the whole ecosphere’s sustainable evolution. Great glaciations might be caused by space body falls into the world oceans. If the body is large enough, it can stir waters down to the bottom. The world waters are part of the global heat transfer from the planet’s equator to its poles (nowadays, mostly to the North Pole). The mixing of the bottom and surface waters breaks the circulation of flows and they stop. The termination of heat transfer to the poles will result in an icecap at high latitudes which in its turn will decrease the total solar heat inflow to the planet and shift the pole ice boarder to the equator. This positive feedback may last long and result in long-time glaciations. The oceanic currents will remain only near the equator. The factor obstructing the global cooling is the greenhouse effect. Volcanic eruptions supply a lot of carbon dioxide into the atmosphere. When due to the increased albedo the planet receives less solar heat, plants bind less carbon oxide into biomass and more of it retains in the atmosphere. Therefore, the outflow of heat from the planet decreases and glaciations does not involve the whole planet. The balance established between the heat inflow and heat losses is unstable. Any imbalance acts as a positive feed-back factor. If the volcanic activity grows, the inflow of the carbon dioxide into the atmosphere will cause its heating-up (plants will fail to reproduce themselves quickly enough to utilize the carbonic acid). The temperature growth will lead to

  15. Carboniferous paleogeographic, phytogeographic, and paleoclimatic reconstructions

    Science.gov (United States)

    Rowley, D.B.; Raymond, A.; Parrish, Judith T.; Lottes, A.L.; Scotese, C.R.; Ziegler, A.M.

    1985-01-01

    Two revised paleogeographic reconstructions of the Visean and Westphalian C-D stages are presented based on recent paleomagnetic, phytogeographic, stratigraphic, and tectonic data. These data change the positions of some continental blocks, and allow the definition of several new ones. The most important modifications that have been incorporated in these reconstructions are: (1) a proposed isthmus linking North America and Siberia across the Bering Strait; and (2) the separation of China and Southeast Asia in six major blocks, including South China, North China, Shan Thai-Malaya, Indochina, Qangtang, and Tarim blocks. Evidence is presented that suggests that at least the South China, Shan Thai-Malaya, and Qangtang blocks were derived from the northern margin of Gondwana. Multivariate statistical analysis of phytogeographic data from the middle and late Paleozoic allow definition of a number of different phytogeographic units for four time intervals: (1) the Early Devonian, (2) Tournaisian-early Visean, (3) Visean, and (4) late Visean-early Namurian A. Pre-late Visean-early Namurian A floral assemblages from South China show affinities with northern Gondwana floras suggesting a southerly position and provides additional support for our reconstruction of South China against the northern margin of Gondwana. There is a marked decrease in the diversity of phytogeographic units in the Namurian and younger Carboniferous. This correlates closely with the time of assembly of most of Pangaea. The general pattern of Carboniferous phytogeographic units corresponds well with global distribution of continents shown on our paleogeographic reconstructions. In addition, we have constructed paleoclimatic maps for the two Carboniferous time intervals. These maps stress the distribution of rainfall, as this should be strongly correlated with the floras. There is marked change in the rainfall patterns between the Visean and Westphalian C-D. This change corresponds with the closing of

  16. Plant biodiversity changes in Carboniferous tropical wetlands

    DEFF Research Database (Denmark)

    Cleal, C. J.; Uhl, D.; Cascales-Miñana, B.

    2012-01-01

    and Sydney coal basins. In all cases, species richness expansion followed an essentially logistic curve typical of that associated with ecologically closed habitats, with niche saturation being achieved in about three million years. The resulting steady-state (“climax”) coal swamp vegetation had a local......Using a combination of species richness, polycohort and constrained cluster analyses, the plant biodiversity of Pennsylvanian (late Carboniferous) tropical wetlands (“coal swamps”) has been investigated in five areas in Western Europe and eastern North America: South Wales, Pennines, Ruhr, Saarland...

  17. Potential For Stratospheric Ozone Depletion During Carboniferous

    Science.gov (United States)

    Bill, M.; Goldstein, A. H.

    Methyl bromide (CH3Br) constitutes the largest source of bromine atoms to the strato- sphere whereas methyl chloride (CH3Cl) is the most abundant halocarbon in the tro- posphere. Both gases play an important role in stratospheric ozone depletion. For in- stance, Br coupled reactions are responsible for 30 to 50 % of total ozone loss in the polar vortex. Currently, the largest natural sources of CH3Br and CH3Cl appear to be biological production in the oceans, inorganic production during biomass burning and plant production in salt marsh ecosystems. Variations of paleofluxes of CH3Br and CH3Cl can be estimated by analyses of oceanic paleoproductivity, stratigraphic analyses of frequency and distribution of fossil charcoal indicating the occurrence of wildfires, and/or by paleoreconstruction indicating the extent of salt marshes. Dur- ing the lower Carboniferous time (Tournaisian-Visean), the southern margin of the Laurasian continent was characterized by charcoal deposits. Estimation on frequency of charcoal layers indicates that wildfires occur in a range of 3-35 years (Falcon-Lang 2000). This suggests that biomass burning could be an important source of CH3Br and CH3Cl during Tournaisian-Viesan time. During Tounaisian and until Merame- cian carbon and oxygen isotope records have short term oscillations (Bruckschen et al. 1999, Mii et al. 1999). Chesterian time (mid- Carboniferous) is marked by an in- crease in delta18O values ( ~ 2 permil) and an increase of glacial deposit frequency suggesting lower temperatures. The occurrence of glacial deposits over the paleopole suggests polar conditions and the associated special features of polar mete- orology such as strong circumpolar wind in the stratosphere (polar vortex) and polar stratospheric clouds. Thus, conditions leading to polar statospheric ozone depletion can be found. Simultaneously an increase in delta13C values is documented. We interpret the positive shift in delta13C as a result of higher bioproductivity

  18. Glaciation in the Andes during the Lateglacial and Holocene

    Science.gov (United States)

    Rodbell, Donald T.; Smith, Jacqueline A.; Mark, Bryan G.

    2009-10-01

    This review updates the chronology of Andean glaciation during the Lateglacial and the Holocene from the numerous articles and reviews published over the past three decades. The Andes, which include some of the world's wettest and driest mountainous regions, offer an unparalleled opportunity to elucidate spatial and temporal patterns of glaciation along a continuous 68-degree meridional transect. The geographic and altitudinal extent of modern glaciers and the sensitivity of both modern and former glaciers to respond to changes in specific climatic variables reflect broad-scale atmospheric circulation and consequent regional moisture patterns. Glaciers in the tropical Andes and in the mid-latitude Andes are likely to have been far more sensitive to changes in temperature than glaciers in the dry subtropical Andes. Broad-scale temporal and spatial patterns of glaciation during the Lateglacial are apparent. In the southernmost Andes, the Lateglacial chronology appears to have a strong Antarctic signature with the best-dated moraines correlating closely with the Antarctic Cold Reversal. The southernmost Andes do not appear to have experienced a significant ice advance coeval with the Younger Dryas (YD) climatic reversal. At the other end of the Andes, from ˜0 to 9°N, a stronger YD connection may exist, but critical stratigraphic and geochronologic work is required before a YD ice advance can be fully demonstrated. In the central Andes of Peru, well-dated moraines record a significant ice readvance at the onset of the YD, but ice was retreating during much of the remaining YD interval. The spatial-temporal pattern of Holocene glaciation exhibits tantalizing but incomplete evidence for an Early to Mid-Holocene ice advance(s) in many regions, but not in the arid subtropical Andes, where moraines deposited during or slightly prior to the Little Ice Age (LIA) record the most extensive advance of the Holocene. In many regions, there is strong evidence for Neoglacial

  19. Influence of Late Paleozoic Gondwana glaciations on the depositional evolution of the northern Pangean shelf, North Greenland, Svalbard and the Barents Sea

    DEFF Research Database (Denmark)

    Stemmerik, Lars

    2008-01-01

    Outcrop and subsurface data from the central northern margin of the Pangean shelf in North Greenland, Svalbard, and the Norwegian Barents Sea record the depositional response of a Northern Hemisphere subtropical shelf to Late Carboniferous-Early Permian (Bashkirian-Sakmarian) Gondwana glaciations....... The dominant motif is that of meters to tens of meters of exposure-capped cycles of carbonates, mixed carbonates, and siliciclastics and, in older stratigraphic levels, siliciclastics and gypsum. Halitegypsum-carbonate cycles developed in deeper, isolated basins. Individual cycles of carbonate and mixed...

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

    Directory of Open Access Journals (Sweden)

    Julien Denayer

    2016-02-01

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

  1. Glaciation and geosphere evolution - Greenland Analogue Project

    International Nuclear Information System (INIS)

    Hirschorn, S.; Vorauer, A.; Belfadhel, M.B.; Jensen, M.

    2011-01-01

    The deep geological repository concept for the long-term management of used nuclear fuel involves the containment and isolation of used nuclear fuel in a suitable geological formation. A key objective of the Canadian Nuclear Waste Management Organization (NWMO) geoscience technical research program is to advance the understanding of geosphere stability and its resilience to perturbations over time frames of relevance to a deep geological repository. Glaciation has been identified as the most probable and intense perturbation relevant to a deep geological repository associated with long-term climate change in northern latitudes. Given that the North American continent has been re-glaciated nine times over the past million years, it is strongly expected that a deep geological repository within a suitable crystalline or sedimentary rock formation in Canada will be subject to glaciation events associated with long-term climate change. As such, NWMO's geoscience research program has placed particular emphasis on investigations of the response of the geosphere to glaciations. As surface conditions change from present day conditions to periglacial, followed by ice-sheet cover of variable thickness and rapid glacial retreat, transient geochemical, hydraulic, mechanical and temperature conditions will be simultaneously imposed on groundwater systems. NWMO research activities related to glaciation events and their impacts on groundwater system evolution are being undertaken using a multi-disciplinary approach aimed at collecting multiple lines of evidence. These investigations include assessment of the: Impact of an ice sheet on groundwater composition at repository depth using the Greenland Ice Sheet as an analogue to future glaciations in North America; Expected physical and temporal surface boundary conditions related to potential future glaciation events by estimating the magnitude and time rate of change of ice sheet thickness, ground surface temperature and

  2. Minimal erosion of Arctic alpine topography during late Quaternary glaciation

    Science.gov (United States)

    Gjermundsen, Endre F.; Briner, Jason P.; Akçar, Naki; Foros, Jørn; Kubik, Peter W.; Salvigsen, Otto; Hormes, Anne

    2015-10-01

    The alpine topography observed in many mountainous regions is thought to have formed during repeated glaciations of the Quaternary period. Before this time, landscapes had much less relief. However, the spatial patterns and rates of Quaternary exhumation at high latitudes--where cold-based glaciers may protect rather than erode landscapes--are not fully quantified. Here we determine the exposure and burial histories of rock samples from eight summits of steep alpine peaks in northwestern Svalbard (79.5° N) using analyses of 10Be and 26Al concentrations. We find that the summits have been preserved for at least the past one million years. The antiquity of Svalbard’s alpine landscape is supported by the preservation of sediments older than one million years along a fjord valley, which suggests that both mountain summits and low-elevation landscapes experienced very low erosion rates over the past million years. Our findings support the establishment of northwestern Svalbard’s alpine topography during the early Quaternary. We suggest that, as the Quaternary ice age progressed, glacial erosion in the Arctic became inefficient and confined to ice streams, and high-relief alpine landscapes were preserved by minimally erosive glacier armour.

  3. Pleistocene glaciation of the Jackson Hole area, Wyoming

    Science.gov (United States)

    Pierce, Kenneth L.; Licciardi, Joseph M.; Good, John M.; Jaworowski, Cheryl

    2018-01-24

    Pleistocene glaciations and late Cenozoic offset on the Teton fault have played central roles in shaping the scenic landscapes of the Teton Range and Jackson Hole area in Wyoming. The Teton Range harbored a system of mountain-valley glaciers that produced the striking geomorphic features in these mountains. However, the comparatively much larger southern sector of the Greater Yellowstone glacial system (GYGS) is responsible for creating the more expansive glacial landforms and deposits that dominate Jackson Hole. The glacial history is also inextricably associated with the Yellowstone hotspot, which caused two conditions that have fostered extensive glaciation: (1) uplift and consequent cold temperatures in greater Yellowstone; and (2) the lowland track of the hotspot (eastern Snake River Plain) that funneled moisture to the Yellowstone Plateau and the Yellowstone Crescent of High Terrain (YCHT).The penultimate (Bull Lake) glaciation filled all of Jackson Hole with glacial ice. Granitic boulders on moraines beyond the south end of Jackson Hole have cosmogenic 10Be exposure ages of ~150 thousand years ago (ka) and correlate with Marine Isotope Stage 6. A thick loess mantle subdues the topography of Bull Lake moraines and caps Bull Lake outwash terraces with a reddish buried soil near the base of the loess having a Bk horizon that extends down into the outwash gravel. The Bull Lake glaciation of Jackson Hole extended 48 kilometers (km) farther south than the Pinedale, representing the largest separation of these two glacial positions in the Western United States. The Bull Lake is also more extensive than the Pinedale on the west (22 km) and southwest (23 km) margins of the GYGS but not on the north and east. This pattern is explained by uplift and subsidence on the leading and trailing “bow-wave” of the YCHT, respectively.During the last (Pinedale) glaciation, mountain-valley glaciers of the Teton Range extended to the western edge of Jackson Hole and built

  4. The low-latitude Rapitan glaciation (Invited)

    Science.gov (United States)

    MacDonald, F. A.; Schmitz, M. D.; Crowley, J. L.; Roots, C.; Maloof, A. C.; Jones, D. S.; Strauss, J.

    2009-12-01

    The snowball Earth hypothesis1 was developed in response to strong palaeomagnetic evidence for low-latitude glaciation from “Marinoan” glacial deposits in the Elatina Formation of Australia. An earlier Cryogenian glaciation, commonly referred to as the “Sturtian” glaciation, has been inferred from the ubiquity of pre-Marinoan glacial deposits; however, the synchroneity and global extent of this event have been questioned due to the lack of precise U/Pb ages and robust paleomagnetic data. Herein we provide new age constraints on the Franklin LIP with revised U/Pb ID-TIMS dates on the the Mt. Harper volcanic complex in the Yukon Territory and the Coronation sills of Victoria Island. Furthermore we present a new age from a tuff interbedded with diamictite in the Upper Mt. Harper Group. A glaciogenic origin of the diamictites is provided by striated clasts and laminae-penetrating dropstones. These glacial deposits can be traced from Alaska westward through the Yukon Territory and into the Northwest Territories, and are correlative to the Rapitan Group. Throughout the Cordillera, the Rapitan Group and its correlatives commonly host iron formation, are the lower of two Cryogenian glacial horizons, and globally are thought to be equivalent to the Sturtian glaciation. The age of the tuff interbedded with the glacial deposits in the Mt. Harper Group is within 1 million years of the revised age on the Franklin LIP. Several paleomagnetic studies on dikes, sills, and basalts spanning >2000 km of NW Canada have agreed that the Franklin LIP erupted when NW Laurentia was in an equatorial position2,3. Consequently, the Sturtian glaciation on Laurentia can now be confidently inferred to have occurred at a very low palaeolatitude. Thus, there were at least two Cryogenian glaciations of global extent. 1 Kirschvink, J.L., in The Proterozoic Biosphere, edited by J. W. Schopf and C. Klein (Cambridge University Press, Cambridge, 1992), pp. 51. 2 Park, J.K., Paleomagnetic

  5. Late Carboniferous Monzonite-Granosyenite Magmatism in the Northern Balkhash Region (Central Kazakhstan)

    Science.gov (United States)

    Ermolov, P. V.; Degtyarev, K. E.; Salnikova, E. B.; Tretyakov, A. A.; Kotov, A. B.; Anisimova, I. V.; Plotkina, Yu. V.

    2018-02-01

    U-Pb dating of the Torangalyk Complex (Northern Balkhash) yielded a Late Carboniferous age of 305 ± 2 Ma. Taking into account the previous data, a new scheme for Late Paleozoic granitic magmatism in this region has been proposed. It includes the Early Carboniferous granite-granodiorite Balkhash Complex, Late Carboniferous monzonite-granosyenite Kokdombak and Torangalyk complexes, and the Late Carboniferous-Early Permian granite-leucogranite Akchatau Complex.

  6. Devonian and Lower Carboniferous conodont biostratigraphy, Spanish Central Pyrenees

    NARCIS (Netherlands)

    Boersma, Kerst Th.

    1973-01-01

    Conodont faunas were collected from the Devonian and Lower Carboniferous in an area ranging from the Rio Fsera (prov. of Huesca) in the west to the Rio Llobregat (prov. of Barcelona) in the east. Most conodont zones and -Faunas recognized in Germany and Spain could be distinguished. The ages of the

  7. Review of monolete-producing Carboniferous-Permian sphenophylls

    Czech Academy of Sciences Publication Activity Database

    Libertín, M.; Bek, Jiří

    2008-01-01

    Roč. 2008, č. 2 (2008), s. 168-168 ISSN 0946-8978. [International Palynological Congress /12./ ; International Organisation of Palaeobotany Conference /8./. 30.08.2008-05.09.2008, Bonn] R&D Projects: GA AV ČR IAA300130503 Institutional research plan: CEZ:AV0Z30130516 Keywords : Carboniferous * Permian * sphenophylls Subject RIV: DB - Geology ; Mineralogy

  8. Taxonomy and stratigraphic importance of the Carboniferous miospore genus Vestispora

    Czech Academy of Sciences Publication Activity Database

    Bek, Jiří; Dimitrova, T.

    2014-01-01

    Roč. 202, March (2014), s. 15-28 ISSN 0034-6667 R&D Projects: GA AV ČR IAA301110701 Institutional support: RVO:67985831 Keywords : Vestispora * stratigraphy * Carboniferous * dispersed in situ spores Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.940, year: 2014

  9. Late Carboniferous to Late Permian carbon isotope stratigraphy

    DEFF Research Database (Denmark)

    Buggisch, Werner; Krainer, Karl; Schaffhauser, Maria

    2015-01-01

    An integrated study of the litho-, bio-, and isotope stratigraphy of carbonates in the Southern Alps was undertaken in order to better constrain δ13C variations during the Late Carboniferous to Late Permian. The presented high resolution isotope curves are based on 1299 δ13Ccarb and 396 δ13Corg...

  10. Paraglacial dynamics in Little Ice Age glaciated environments in the Iberian Peninsula

    Science.gov (United States)

    Oliva, Marc; Serrano, Enrique; Ruiz-Fernández, Jesús; Gómez-Ortiz, Antonio; Palacios, David

    2017-04-01

    Three Iberian mountain ranges encompassed glaciers during the Little Ice Age (LIA): the Pyrenees, Cantabrian Mountains and Sierra Nevada. The gradual warming trend initiated during the second half of the XIX century promoted the progressive shrinking of these glaciers, which completely melted during the first half of the 20th century in the Cantabrian Mountains and Sierra Nevada and reduced by 80% of their LIA extent in the Pyrenees. Currently, the formerly glaciated environments are located within the periglacial belt and still present to a major or lesser degree signs of paraglacial activity. LIA moraines are devoid of vegetation and composed of highly unstable sediments that are being intensely mobilized by slope processes. Inside the moraines, different landforms and processes generated following LIA glacial retreat have generated: (i) buried ice trapped within rock debris supplied from the cirque walls, which has also generated rock glaciers and protalus lobes; (ii) semi-permanent snow fields distributed above the ice-patches remnants of the LIA glaciers, and (iii) small periglacial features such as frost mounds, sorted circles and solifluction landforms generated by processes such as solifluction and cryoturbation. Present-day morphodynamics is mostly related to seasonal frost conditions, though patches of permafrost have formed in some areas in contact with the buried ice. This 'geomorphic permafrost' is undergoing a process of degradation since it is not balanced with present-day climate conditions. This is reflected in the occurrence of multiple collapses and subsidences of the debris cover where the frozen bodies sit. In the highest areas of the Pyrenees there is a permafrost belt next to the small glaciated environments in the highest massifs. Finally, we propose a model for paraglacial activity in Iberian mountain ranges and compare it to other mid-latitude mountain environments as well as to other past deglaciation stages.

  11. Thermokarst transformation of permafrost preserved glaciated landscapes.

    Science.gov (United States)

    Kokelj, S.; Tunnicliffe, J. F.; Fraser, R.; Kokoszka, J.; Lacelle, D.; Lantz, T. C.; Lamoureux, S. F.; Rudy, A.; Shakil, S.; Tank, S. E.; van der Sluijs, J.; Wolfe, S.; Zolkos, S.

    2017-12-01

    Thermokarst is the fundamental mechanism of landscape change and a primary driver of downstream effects in a warming circumpolar world. Permafrost degradation is inherently non-linear because latent heat effects can inhibit thawing. However, once this thermal transition is crossed thermokarst can accelerate due to the interaction of thermal, physical and ecological feedbacks. In this paper we highlight recent climate and precipitation-driven intensification of thaw slumping that is transforming permafrost preserved glaciated landscapes in northwestern Canada. The continental distribution of slump affected terrain reflects glacial extents and recessional positions of the Laurentide Ice sheet. On this basis and in conjunction with intense thermokarst in cold polar environments, we highlight the critical roles of geological legacy and climate history in dictating the sensitivity of permafrost terrain. These glaciated landscapes, maintained in a quasi-stable state throughout much of the late Holocene are now being transformed into remarkably dynamic environments by climate-driven thermokarst. Individual disturbances displace millions of cubic metres of previously frozen material downslope, converting upland sedimentary stores into major source areas. Precipitation-driven evacuation of sediment by fluidized mass flows perpetuates non-linear enlargement of disturbances. The infilling of valleys with debris deposits tens of metres thick increases stream base-levels and promotes rapid valley-side erosion. These processes destabilize adjacent slopes and proliferate disturbance effects. Physically-based modeling of thaw slump development provides insight into the trajectories of landscape change, and the mapping of fluvial linkages portrays the cascade of effects across watershed scales. Post-glacial or "paraglacial" models of landscape evolution provide a useful framework for understanding the nature and magnitude of climate-driven changes in permafrost preserved glaciated

  12. Late carboniferous foreland basin formation and Early Carboniferous stretching in Northwestern Europe: Inferences from quantitative subsidence analyses in the Netherlands

    NARCIS (Netherlands)

    Kombrink, H.; Leever, K.A.; Wees, J.-D. van; Bergen, F. van; David, P.; Wong, T.E.

    2008-01-01

    The large thickness of Upper Carboniferous strata found in the Netherlands suggests that the area was subject to long-term subsidence. However, the mechanisms responsible for subsidence are not quantified and are poorly known. In the area north of the London Brabant Massif, onshore United Kingdom,

  13. The timing of Late Pleistocene glaciation at Mount Wilhelm, Papua New Guinea

    Science.gov (United States)

    Mills, Stephanie; Barrows, Timothy; Hope, Geoff; Pillans, Brad; Fifield, Keith

    2016-04-01

    The highlands of New Guinea were the most extensively glaciated area in the Asian tropical region during the Late Pleistocene. Evidence for glaciation is widespread on most of the mountain peaks above ~3500 m. Glacial landforms include both valley and ice cap forms, but the timing of glaciation remains constrained to only a few local areas. This paper focuses on Mount Wilhelm, which is situated in the central southern region of Papua New Guinea at 5.78°S and is the highest peak (4510 m a.s.l.) We focus on a south easterly valley (Pindaunde Valley) emanating from the peak, where large moraines indicate the maximum ice extent of a valley glacier ~5 km long. Within this extensive moraine complex, recessional moraines document the retreat of the glacier towards the summit region. In order to determine the timing of deglaciation, we collected samples for surface exposure dating using 36Cl and 10Be from diorite boulders positioned on moraine crests. The ages indicate that maximum ice extent was attained during the last glacial maximum (LGM) and that ice remained near its maximum extent until after 15 ka but persisted at higher elevations almost until the Holocene. These results are similar to those described from Mt Giluwe to the northwest of Mount Wilhelm, where an ice cap reached its maximum extent at the LGM and remained there for around 3-4,000 years. This indicates that full glacial conditions were only brief in this region of the tropics.

  14. Geochronology of Quaternary glaciations from the tropical Cordillera Huayhuash, Peru

    Science.gov (United States)

    Hall, Sarah R.; Farber, Daniel L.; Ramage, Joan M.; Rodbell, Donald T.; Finkel, Robert C.; Smith, Jacqueline A.; Mark, Bryan G.; Kassel, Christopher

    2009-12-01

    The Cordillera Huayhuash in the central Peruvian Andes (10.3°S, 76.9°W) is an ideal mountain range in which to study regional climate through variations in paleoglacier extents. The range trends nearly north-south with modern glaciers confined to peaks >4800 m a.s.l. Geomorphology and geochronology in the nearby Cordillera Blanca and Junin Plain reveal that the Peruvian Andes preserve a detailed record of tropical glaciation. Here, we use ASTER imagery, aerial photographs, and GPS to map and date glacial features in both the western and eastern drainages of the Cordillera Huayhuash. We have used in situ produced cosmogenic 10Be concentrations in quartz bearing erratics on moraine crests and ice-polished bedrock surfaces to develop an exposure age chronology for Pleistocene glaciation within the range. We have also collected sediment cores from moraine-dammed lakes and bogs to provide limiting 14C ages for glacial deposits. In contrast to the ranges to the north and south, most glacial features within the Cordillera Huayhuash are Lateglacial in age, however we have identified features with ages that span ˜0.2 to ˜38 ka with moraine sets marking the onset of glacier retreat at ˜0.3 ka, ˜9-10 ka, ˜13-14 ka, ˜20-22 ka, and >26 ka. The range displays a pronounced east-west variation in maximum down-valley distance from the headwall of moraine crests with considerably longer paleoglaciers in the eastern drainages. Importantly, Lateglacial paleoglaciers reached a terminal elevation of ˜4000 m a.s.l. on both sides of the Cordillera Huayhuash; suggesting that temperature may have been a dominant factor in controlling the maximum glacier extent. We suggest that valley morphology, specifically valley slope, strongly influences down-valley distance to the maximum glacier extent and potential for moraine preservation. While regionally there is an extensive record of older (>50 ka) advances to the north (Cordillera Blanca) and to the south (Junin region), the apparent

  15. Asymmetric lithosphere as the cause of rifting and magmatism in the Permo-Carboniferous Oslo Graben, in Permo-Carboniferous Rifting and Magmatism in Europe.

    NARCIS (Netherlands)

    Pascal Candas, C.; Cloetingh, S.A.P.L.; Davies, G.R.

    2004-01-01

    Compared to other Permo-Carboniferous rift basins of NW Europe, the Oslo Graben has two distinct characteristics. First, it initiated inside cold and stable Precambrian lithosphere, whereas most Permo-Carboniferous basins developed in weaker Phanerozoic lithosphere, and second, it is characterized

  16. Carboniferous volcanic rocks associated with back-arc extension in the western Chinese Tianshan, NW China: Insight from temporal-spatial character, petrogenesis and tectonic significance

    Science.gov (United States)

    Su, Wenbo; Cai, Keda; Sun, Min; Wan, Bo; Wang, Xiangsong; Bao, Zihe; Xiao, Wenjiao

    2018-06-01

    The Yili-Central Tianshan Block, as a Late Paleozoic major continental silver of the Central Asian Orogenic Belt, holds a massive volume of Carboniferous volcanic rocks, occurring as subparallel magmatic belts. However, the petrogenesis and tectonic implications of these volcanic rocks remain enigmatic. This study compiled isotopic age data for mapping their temporal-spatial character, and conducted petrogenetic study of these magmatic belts, aiming to understand their tectonic implications. Our compiled dataset reveals four magmatic belts in the Yili-Central Tianshan Block, including the Keguqinshan-Tulasu belt and the Awulale belt in the north, and the Wusun Mountain belt and the Haerk-Nalati belt in the south. In addition, our new zircon U-Pb dating results define two significant Early Carboniferous eruptive events (ca. 355-350 Ma and 325 Ma) in the Wusun Mountain belt. Volcanic rocks of the early significant eruptive event (ca. 355-350 Ma) in the Wusun Mountain comprise basalt, trachy-andesite, andesite, dacite and rhyolite, which are similar to the typical rock assemblage of a continental arc. Their positive εNd(t) values (+0.3 to +1.5) and relatively high Th/Yb and Nb/Yb ratios suggest the derivation from a mantle source with additions of slab-derived components. The gabbroic dykes and rhyolites of the late volcanic event (ca. 325 Ma) form a bimodal rock association, and they show alkaline features, with relatively low Th/Yb and Th/Nb ratios, and higher positive εNd(t) values (εNd(t) = +3.3-+5.0). It is interpreted that the gabbroic dykes and rhyolites may have been derived from mantle and juvenile crustal sources, respectively. The isotopic and trace elemental variations with time elapse of the Wusun Mountain magmatic belt show an important clue for strengthening depletion of the magma sources. Considering the distinctive temporal-spatial character of the Carboniferous volcanic rocks, two separate subduction systems in the southern and northern margins of

  17. Contrasting Permo - Carboniferous Evolution of Resita and Sirinia - Presacina Basins (South Carpathians, Romania); an overview.

    Science.gov (United States)

    Tatu, M.; Seghedi, I.; Nutu, L. M.; Nicolae, I.

    2009-04-01

    Two important Permo-Carboniferous molasses basins Resita and Sirinia - Presacina occur in Romanian Banat (south-western part of Carpathian chain), unconformable overlie the Getic and Danubian domains with different pre-Variscan and Variscan geodynamic history. They show differences in their lithology reflecting various geotectonic settings and evolutions. In the Resita domain the Upper Carboniferous deposits (Westphalian - Stephanian in age, according to the previous paleobotanic and palynological data) are important in volume and they contain terrigeneous siliciclastic rocks represented by sandy - conglomerate and argillaceous - sandy rocks variable in thickness with siltstone, carbonaceous shale and coal beds interlayering. There are not volcanic rocks present in Upper Carboniferous of Resita domain. In contrast with Resita in the Sirinia - Presacina basins the Upper Carboniferous deposits are volumetrically more restrictive. These deposits transgresively overlie pre-Sudetian formations and consist of continental - lacustrine terrigeneous formations, rarely associated with limnic carbonatic rocks. In this association the alternating conglomerate, siliceous sandstone, siltstone and clay with lens - like coal inter-layers prevails. In two small areas Dragosela - Tulinecea - Camenita (in the western part) and Baia Noua - Cucuiova (in the eastern part) the terrigeneous deposits are associated with basaltic andesite and andesite rocks with alkaline affinity. In both of these basins the Lower Permian deposits (according to the paleobotanic data) unconformably overlie the Upper Carboniferous formations and/or pre-Sudetian basements. The Lower Permian deposits in the Resita basin occur in two superposed formations (Nastaseanu, 1987): (1) Walchia Beds dominated by black argillaceous shales, slightly bituminous with rare sandy-conglomerate interlayers and (2) Red Beds composed by sandy-conglomerate deposits with some argillaceous intercalations, all red in color, with

  18. LATE DEVONIAN-CARBONIFEROUS CONODONTS FROM EASTERN IRAN

    Directory of Open Access Journals (Sweden)

    MEHDI YAZDI

    1999-07-01

    Full Text Available Conodont data from acid-leaching 110 samples from two Late Devonian-Carboniferous areas in the Shotori Range (Tabas region of eastern Iran are presented. At Howz-e-Dorah, a section (88 samples commencing high in the Bahram Formation (Givetian-early Frasnian extended through the Shishtu Formation (Frasnian, Early hassi Zone or older, to latest Tournaisian, anchoralis-latus Zone and the Sardar Formation (earliest Visean, texanus Zone, to late Namurian, sinuatus-corrugatus-sulcatus Zone and into the Jamal Formation (Permian. Four less exhaustively sampled sections (22 samples show the Kale Sardar area to be tectonically more complicated than the Howz-e-Dorah area. Useful marker horizons in the Howz-e-Dorah section, well constrained by conodont data, are: the early Frasnian (no older than Early hassi Zone biostromal beds of the Shishtu Formation, an early Famennian (Late triangularis to Early crepida interval of oolitic limestone, a cyclothem sequence straddling the Early Carboniferous-Late Carboniferous boundary, and an Early Permian interval of siliceous sand ("the white quartzite" of previous authors. Additionally, several iron-rich horizons, readily traceable from locality to locality, are well constrained by conodont ages. Eighty-five conodont species/subspecies are documented representing 24 genera.. Two new species, Polygnathus capollocki and Polygnathus ratebi and one new subspecies, Icriodus alternatus mawsonae are described. 

  19. Middle and Late Pleistocene glaciations in the southwestern Pamir and their effects on topography [Topography of the SW Pamir shaped by middle-late Pleistocene glaciation

    International Nuclear Information System (INIS)

    Stübner, Konstanze; Grin, Elena; Hidy, Alan J.; Schaller, Mirjam; Gold, Ryan D.

    2017-01-01

    Glacial chronologies provide insight into the evolution of paleo-landscapes, paleoclimate, topography, and the erosion processes that shape mountain ranges. In the Pamir of Central Asia, glacial morphologies and deposits indicate extensive past glaciations, whose timing and extent remain poorly constrained. Geomorphic data and 15 new "1"0Be exposure ages from moraine boulders and roches moutonnées in the southwestern Pamir document multiple Pleistocene glacial stages. The oldest exposure ages, View the MathML source113 ± 10ka, underestimate the age of the earliest preserved glacial advance and imply that the modern relief of the southwestern Pamir (peaks at ~5000–6000 m a.s.l.; valleys at ~2000–3000 m a.s.l.) already existed in the late Middle Pleistocene. Younger exposure ages (~40–80 ka, ~30 ka) complement the existing Central Asian glacial chronology and reflect successively less extensive Late Pleistocene glaciations. The topography of the Pamir and the glacial chronologies suggest that, in the Middle Pleistocene, an ice cap or ice field occupied the eastern Pamir high-altitude plateau, whereas westward flowing valley glaciers incised the southwestern Pamir. Since the Late Pleistocene deglaciation, the rivers of the southwestern Pamir adjusted to the glacially shaped landscape. As a result, localized rapid fluvial incision and drainage network reorganization reflect the transient nature of the deglaciated landscape.

  20. Carboniferous Psammichnites: Systematic re-evaluation, taphonomy and autecology

    Science.gov (United States)

    Mángano, M. Gabriela; Rindsberg, Andrew K.

    2002-01-01

    The ichnogenus Psammichnites Torell 1870 includes a wide variety of predominantly horizontal, sinuous to looped, backfilled traces, characterized by a distinctive median dorsal structure. Though commonly preserved in full relief on upper bedding surfaces, some ichnospecies of Psammichnites may be preserved in negative hyporelief. Psammichnites records the feeding activities of a subsurface animal using a siphon-like device. Several ichnogenera reflect this general behavioral pattern, including Plagiogmus Roedel 1929 and the Carboniferous ichnogenera Olivellites Fenton and Fenton 1937a and Aulichnites Fenton and Fenton 1937b. Based on analysis of specimens from the United States, Spain, and the United Kingdom, three Carboniferous ichnospecies of Psammichnites are reviewed in this paper: P. plummeri (Fenton and Fenton, 1937a), P. grumula(Romano and Meléndez 1979), and P. implexus (Rindsberg 1994). Psammichnites plummeri is the most common Carboniferous ichnospecies and is characterized by a relatively straight, continuous dorsal ridge/groove, fine transverse ridges, larger size range, and non-looping geometric pattern. It represents a grazing trace of deposit feeders. Psammichnites grumula differs from the other ichnospecies of Psammichnitesby having median dorsal holes or protruding mounds. The presence of mounds or holes in P. grumulasuggests a siphon that was regularly connected to the sediment-water interface. This ichnospecies is interpreted as produced by a deposit feeder using the siphon for respiration or as a device for a chemosymbiotic strategy. Psammichnites implexus is characterized by its consistently smaller size range, subtle backfill structure, and tendency to scribble. Although displaying similarities with Dictyodora scotica, P. implexus is a very shallow-tier, grazing trace. Changes in behavioral pattern, preservational style, and bedform morphology suggest a complex interplay of ecological and taphonomic controls in

  1. The tectonic and stratigraphic history of the Cardaño area, Cantabrian mountains, Northwest Spain

    NARCIS (Netherlands)

    Veen, van J.

    1965-01-01

    The Devonian and Carboniferous rock-sequence in the Cantabrian Mountains is developed in two different facies which are separated by an E-W tectonic line, the León Line, and called the Leonide and Palentian facies, respectively to the S and N. The Leonide facies is widely exposed throughout the

  2. The geology of the Valderrueda, Tejerina, Ocejo and Sabero coal basins (Cantabrian Mountains, Spain)

    NARCIS (Netherlands)

    Helmig, H.M.

    1965-01-01

    Four Upper Carboniferous limnic coal basins in the Cantabrian mountains are described. In the coal measures, which are known as the Cea formation and unconformably overlie the Older Palaeozoic, two sedimentary cycles are recognised. Accordingly, the unconformable sequence is subdivided into two

  3. LATEST TOURNAISIAN (EARLY CARBONIFEROUS CONODONTS FROM THE TABAI LIMESTONE, TIRAH, NORTHWESTERN PAKISTAN

    Directory of Open Access Journals (Sweden)

    FAZL-I-RABBI KHAN

    2004-11-01

    Full Text Available A new stratigraphic unit, the Tabai Limestone of the poorly known Tirah area of northwest Pakistan, is one of several Early Carboniferous carbonate units distributed along the North Gondwana margin, some connected with transgressive interludes. The Tabai Limestone has produced latest Tournaisian (Early Carboniferous conodonts indicative of the middle of the anchoralis-latus Zone.

  4. Data-mining Based Detection of Glaciers: Quantifying the Extent of Alpine Valley Glaciation

    Directory of Open Access Journals (Sweden)

    Wei Luo

    2015-07-01

    Full Text Available The extent of glaciation in alpine valleys often gives clues to past climates, plate movement, mountain landforms, bedrock geology and more. However, without field investigation, the degree to which a valley was affected by a glacier has been difficult to assess. We developed a model that uses quantitative parameters derived from digital elevations model (DEM data to predict whether a glacier was likely present in an alpine valley. The model's inputs are mainly derived from the basin hypsometry, and a new parameter termed the Hypothetical Basin Equilibrium Elevation (HBEE, which is based on the equilibrium elevation altitude (ELA of a glacier. We used data mining techniques that comb through large data sets to find patterns for classification and prediction as the basis for the model. Four classifiers were utilized, and each was tested with two different training set/test data ratios of nearly 150 basins that were previously delineated as fully- or non-glaciated. The classifiers had a predictive accuracy of up to 90% with none falling below 72%. Two of the classifiers, classification tree and naïve-Bayes, have graphical outputs that visually describe the classification process, predictive results, and in the naïve-Bayes case, the relative effectiveness towards the model of each attribute. In all scenarios, the HBEE was found to be an accurate predictor for the model. The model can be applied to any area where glaciation may have occurred, but is particularly useful in areas where the valley is inaccessible for detailed field investigation.

  5. Late Carboniferous and Early Permian algal microflora (Liuzhou, South China)

    Energy Technology Data Exchange (ETDEWEB)

    Li Chun (Nanjing Inst. of Geology and Paleontology, Nanjing (China)); Mamet, B. (Montreal Univ., PQ (Canada))

    1993-03-01

    Paleozoic algae are important contributors to the formation of carbonate sediments. A study was conducted to compare an Upper Carboniferous-Lower Permian carbonate succession of South China with what is generally observed in the Tethys Sea and North America. The sequence studied was in the Maping Limestone at the Loutishan section in Liuzhou, with some additional information derived from the Maping Limestone at Shangxinping and from the Chuanshan Limestone at Yuhuangshan and in the Nanjing Hills. In the Late Carboniferous, the beresellid algae are important builders and the Tubiphytes-Archaeolithophyllum community is locally replaced by a Tubiphytes-Ungdarella association. Early Permian oncolites were formed by complex Osagia, then by Esmerella. The Asselian Sphaeroschwagerina fauna is underlined by the outburst of epimastoporid dasycladales and phylloid Anchicodiaceae. Microcodium is observed at the contact of the Sphaeroschwagerina moelleri/sphaerica Zones. The overlying and paraconformable Chihsia Limestone is characterized by a Gymnocodium-Gyroporella-Mizzia flora. In most cases, the base of the fusulinid zones, therefore, coincides with an important local floristic change. 72 refs., 4 figs.

  6. Late Pleistocene glaciations of the arid subtropical Andes and new results from the Chajnantor Plateau, northern Chile

    Science.gov (United States)

    Ward, Dylan J.; Cesta, Jason M.; Galewsky, Joseph; Sagredo, Esteban

    2015-11-01

    The spatiotemporal pattern of glaciation along the Andes Mountains is an important proxy record reflecting the varying influence of global and regional circulation features on South American climate. However, the timing and extent of glaciation in key parts of the orogen, particularly the deglaciated arid Andes, are poorly constrained. We present new cosmogenic 10Be and 36Cl exposure ages for glacial features on and near the Chajnantor Plateau (23 °S). The new dates, although scattered due to cosmogenic inheritance, imply that the most recent extensive glacial occupation ended before or during the global Last Glacial Maximum (LGM). We discuss this new record in the context of published glacial chronologies from glacial features in Peru, Bolivia, and northern Chile rescaled using the latest cosmogenic 10Be production rate calibration for the tropical Andes. The results imply regionally synchronous moraine stabilization ca. 25-40 ka, 15-17 ka, and 12-14 ka, with the youngest of these moraines absent in records south of ∼20 °S, including in our new Chajnantor area chronology. This spatial pattern implicates easterly moisture in generating sufficient snowfall to glaciate the driest parts of the Andes, while allowing a role for westerly moisture, possibly modulated by the migration of the Southern Westerly Wind belt, in the regions near and south of the Atacama Desert.

  7. The Evolution of Northern Hemisphere Glaciation

    Science.gov (United States)

    Wright, J. D.

    2001-05-01

    For much of the last 50 million years, high-latitude regions remained too warm to allow snow to accumulate and form ice sheets. Shackleton et al. (1984) published a landmark paper correlating the first occurrence of ice-rafted detritus (IRD) observed at Rockall Plateau with a prominent increase in benthic foraminiferal d18O values during the late Pliocene. These late Pliocene to Pleistocene ice sheets were modulated on an orbital frequency and have characterized the global climate over the past 2.6 myr (Shackleton and Opdyke, 1973; Shackleton et al., 1984; Ruddiman, et al., 1986). During the early Pliocene, northern hemisphere glaciation (NHG) variations were less significant (Jansen et al., 1993). Our understanding of the Plio-Pleistocene ice sheet cycles can be viewed from two different perspectives. When viewed from the late Pleistocene, the fundamental question is what changed near the early/late Pliocene boundary to produce the large-scale, glacial-interglacial cycles of the past 2.6 Ma. In contrast, the view from the middle to late Miocene is quite different. Since the pioneering work of Shackleton et al. (1984), the record of NHG has been extended further back in time with drilling in the Norwegian Sea (ODP Leg 104). At Sites 642 and 644, IRD was found throughout the late Miocene and back to ~12 Ma. More recent drilling in the high northern latitudes occurred on ODP Leg 151. Site 909 recovered a middle Miocene section from the Fram Straits with rounded quartz grains that were interpreted as IRD (Wolf-Welling et al., 1996). Age estimates for those sediments place the first northern hemisphere ice sheets at least as old as 14 Ma. The occurrence of sand-sized particles (>1000 μm) and coal below this level indicates the possibility of glacial activity in the Northern Hemisphere as early as 16 Ma. Thus, the late Pliocene to Pleistocene cycles appear to be the resumption of the glacial-interglacial pattern that began during the Miocene. While the Miocene ice

  8. Towards Greenland Glaciation: cumulative or abrupt transition?

    Science.gov (United States)

    Ramstein, Gilles; Tan, Ning; Ladant, Jean-baptiste; Dumas, Christophe; Contoux, Camille

    2017-04-01

    During the mid-Pliocene warming period (3-3.3 Ma BP), the global annual mean temperatures inferred by data and model studies were 2-3° warmer than pre-industrial values. Accordingly, Greenland ice sheet volume is supposed to reach at the most, only half of that of present-day [Haywood et al. 2010]. Around 2.7-2.6 Ma BP, just ˜ 500 kyr after the warming peak of mid-Pliocene, the Greenland ice sheet has reached its full size [Lunt et al. 2008]. A crucial question concerns the evolution of the Greenland ice sheet from half to full size during the 3 - 2.5 Ma period. Data show a decreasing trend of atmospheric CO2 concentration from 3 Ma to 2.5 Ma [Seki et al.2010; Bartoli et al. 2011; Martinez et al. 2015]. However, a recent study [Contoux et al. 2015] suggests that a lowering of CO2 is not sufficient to initiate a perennial glaciation on Greenland and must be combined with low summer insolation to preserve the ice sheet during insolation maxima. This suggests rather a cumulative process than an abrupt event. In order to diagnose the evolution of the ice sheet build-up, we carry on, for the first time, a transient simulation of climate and ice sheet evolutions from 3 Ma to 2.5 Ma. This strategy enables us to investigate the waxing and waning of the ice sheet during several orbital cycles. We use a tri-dimensional interpolation method designed by Ladant et al. (2014), which allows the evolution of CO2 concentration and of orbital parameters, and the evolution of the Greenland ice sheet size to be taken into account. By interpolating climatic snapshot simulations ran with various possible combinations of CO2, orbits and ice sheet sizes, we can build a continuous climatic forcing that is then used to provide 500 kyrs-long ice sheet simulations. With such a tool, we may offer a physically based answer to different CO2 reconstructions scenarios and analyse which one is the most consistent with Greenland ice sheet buildup.

  9. Impact of glaciations on the long-term erosion in Southern Patagonian Andes

    Science.gov (United States)

    Simon-Labric, Thibaud; Herman, Frederic; Baumgartner, Lukas; Shuster, David L.; Braun, Jean; Reiners, Pete W.; Valla, Pierre G.; Leuthold, Julien

    2014-05-01

    The Southern Patagonian Andes are an ideal setting to study the impact of Late-Cenozoic climate cooling and onset of glaciations impact on the erosional history of mountain belts. The lack of tectonic activity during the last ~12 Myr makes the denudation history mainly controlled by surface processes, not by tectonics. Moreover, the glaciations history of Patagonia shows the best-preserved records within the southern hemisphere (with the exception of Antarctica). Indeed, the dry climate on the leeward side of Patagonia and the presence of lava flows interbedded with glacial deposits has allowed an exceptional preservation of late Cenozoic moraines with precise dating using K-Ar analyses on lava flow. The chronology of moraines reveals a long history covering all the Quaternary, Pliocene, and up to the Upper Miocene. The early growth of large glaciers flowing on eastern foothills started at ~7-6 Myr, while the maximum ice-sheet extent dates from approximately 1.1 Myr. In order to quantify the erosion history of the Southern Patagonian Andes and compare it to the glaciations sediment record, we collected samples along an age-elevation profile for low-temperature thermochronology in the eastern side of the mountain belt (Torres del Paine massif). The (U-Th)/He age-elevation relationship shows a clear convex shape providing an apparent long-term exhumation rate of ~0.2 km/Myr followed by an exhumation rate increase at ~6 Myr. Preliminary results of 4He/3He thermochronometry for a subset of samples complete the erosion history for the Plio-Pleistocene epoch. We used inverse procedure predicting 4He distributions within an apatite grain using a radiation-damage and annealing model to quantify He-diffusion kinetics in apatite. The model also allows quantifying the impact of potential U-Th zonation throughout each apatite crystal. Inversion results reveal a denudation history composed by a pulse of denudation at ~6 Ma, as suggested by the age-elevation relationship

  10. Effects of water infusions on mechanical properties of carboniferous rocks

    Energy Technology Data Exchange (ETDEWEB)

    Vavro, M; Chlebik, J

    1977-01-01

    Method of water infusion is used in the Ostrava-Karvina coal region in Czechoslovakia, where the roof of the extracted coal seam consists of thick rock layers (sandstone, Namurian B series) characterized by high resistance to compression, high coefficient of linear elasticity and high capacity of accumulating energy. When the resistance boundary is crossed and the rocks are disturbed this energy is suddenly released and transferred to the surrounding rock masses, coal seam and support system. On the basis of laboratory experiments the physico-mechanical and energy properties of carboniferous rocks together with calculation of their energy coefficient and other parameters are described and calculated. The results of research and theoretical solutions are presented. Practical use of water infusions to influence mechanical properties of sandstone in the roof of coal seams is described with the example of the Dukla coal mine. (5 refs.) (In Polish)

  11. The major-ion composition of Carboniferous seawater

    Science.gov (United States)

    Holt, Nora M.; García-Veigas, Javier; Lowenstein, Tim K.; Giles, Peter S.; Williams-Stroud, Sherilyn

    2014-06-01

    The major-ion chemistry (Na+, Mg2+, Ca2+, K+, SO42-, and Cl-) of Carboniferous seawater was determined from chemical analyses of fluid inclusions in marine halites, using the cryo scanning electron microscopy (Cryo-SEM) X-ray energy-dispersive spectrometry (EDS) technique. Fluid inclusions in halite from the Mississippian Windsor and Mabou Groups, Shubenacadie Basin, Nova Scotia, Canada (Asbian and Pendleian Substages, 335.5-330 Ma), and from the Pennsylvanian Paradox Formation, Utah, USA, (Desmoinesian Stage 309-305 Ma) contain Na+-Mg2+-K+-Ca2+-Cl- brines, with no measurable SO42-, which shows that the Carboniferous ocean was a “CaCl2 sea”, relatively enriched in Ca2+ and low in SO42- with equivalents Ca2+ > SO42- + HCO3-. δ34S values from anhydrite in the Mississippian Shubenacadie Basin (13.2-14.0 ‰) and the Pennsylvanian Paradox Formation (11.2-12.6 ‰) support seawater sources. Br in halite from the Shubenacadie Basin (53-111 ppm) and the Paradox Basin (68-147 ppm) also indicate seawater parentages. Carboniferous seawater, modeled from fluid inclusions, contained ∼22 mmol Ca2+/kg H2O (Mississippian) and ∼24 mmol Ca2+/kg H2O (Pennsylvanian). Estimated sulfate concentrations are ∼14 mmol SO42-/kg H2O (Mississippian), and ∼12 mmol SO42-/kg H2O (Pennsylvanian). Calculated Mg2+/Ca2+ ratios are 2.5 (Mississippian) and 2.3 (Pennsylvanian), with an estimated range of 2.0-3.2. The fluid inclusion record of seawater chemistry shows a long period of CaCl2 seas in the Paleozoic, from the Early Cambrian through the Carboniferous, when seawater was enriched in Ca2+ and relatively depleted in SO42-. During this ∼200 Myr interval, Ca2+ decreased and SO42- increased, but did not cross the Ca2+-SO42- chemical divide to become a MgSO4 sea (when SO42- in seawater became greater than Ca2+) until the latest Pennsylvanian or earliest Permian (∼309-295 Ma). Seawater remained a MgSO4 sea during the Permian and Triassic, for ∼100 Myr. Fluid inclusions also record

  12. Astronomical cycles in the Serpukhovian-Moscovian (Carboniferous) marine sequence, South China and their implications for geochronology and icehouse dynamics

    Science.gov (United States)

    Fang, Qiang; Wu, Huaichun; Wang, Xunlian; Yang, Tianshui; Li, Haiyan; Zhang, Shihong

    2018-05-01

    The Late Paleozoic Ice Age (ca. 335-260 Ma, LPIA) has long been considered as an analogy for the Cenozoic ice age since the Oligocene. The impact of astronomical forcing on the LPIA glaciation has been hampered due to the low-resolution (multi-million year scale) time framework. In the present study, high-resolution cyclostratigraphy based on magnetic susceptibility (MS), covering the Serpukhovian to late Moscovian icehouse climate, has been investigated in the Luokun section of South China. Power spectral analysis of the MS series reveals 3.44-4 m, 0.8-1.07 m, 0.3-0.32 m, and 0.17-0.19 m thick sedimentary cycles. Based on the available biostratigraphic constraints, calibrating the 3.44-4 m cycles to the 405 kyr eccentricity cycles indicates short eccentricity (136 and 100 kyr), short obliquity (34 kyr), and precession (19 and 15.9 kyr) orbital bands in addition to long eccentricity (405 kyr) band. We assigned the basal Serpukhovian and Moscovian stages in Luokun with the numerical ages from Geological Time Scale 2012 to construct two floating time scales ranging from 331.55 ± 0.5 Ma to 323.2 ± 0.5 Ma, and from 315.34 ± 0.35 Ma to 310.17 ± 0.35 Ma, respectively. The modulation of main obliquity (s4-s3 term) has a main periodicity of ∼1200 kyr. The modulation of ∼100 kyr eccentricity (g4-g3 term) shows a main periodicity of ∼2400 kyr with subordinate periodicities of ∼1620 and ∼1200 kyr for the Serpukhovian, and a main periodicity of ∼1600 kyr for the Moscovian. They may provide the geological evidence for a chaotic resonance associated with interactions between the orbits of Mars and the Earth in the Carboniferous. A duration of 7.68 ± 0.15 Myr was estimated for the Serpukhovian Stage. Eight higher accumulation rate events due to glacioeustatic drawdown were temporally constrained, and show close correspondence to far-field and near-field reconstructions of the LPIA glaciation. Glacioeustasy was paced with 405-kyr-long eccentricity and 1.2-Myr

  13. Expert Panel Elicitation of Seismicity Following Glaciation in Sweden

    International Nuclear Information System (INIS)

    Hora, Stephen; Jensen, Mikael

    2005-12-01

    The Swedish Radiation Protection Authority, the Swedish Nuclear Power Inspectorate and the Swedish Nuclear Fuel and Waste Management Company have jointly carried out a project on expert panel elicitation on the issue of glacial induced Swedish earthquakes. Following a broad nomination procedure, 5 experts were chosen by a selection committee of 4 professors within Earth sciences disciplines. The 5 experts presented judgments about the frequency of earthquakes greater the magnitude 6 within 10 km for two Swedish sites, Oskarshamn and Forsmark, in connection with a glaciation cycle. The experts' median value vas 0,1 earthquakes for one glaciation cycle

  14. Expert Panel Elicitation of Seismicity Following Glaciation in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Hora, Stephen; Jensen, Mikael (eds.)

    2005-12-15

    The Swedish Radiation Protection Authority, the Swedish Nuclear Power Inspectorate and the Swedish Nuclear Fuel and Waste Management Company have jointly carried out a project on expert panel elicitation on the issue of glacial induced Swedish earthquakes. Following a broad nomination procedure, 5 experts were chosen by a selection committee of 4 professors within Earth sciences disciplines. The 5 experts presented judgments about the frequency of earthquakes greater the magnitude 6 within 10 km for two Swedish sites, Oskarshamn and Forsmark, in connection with a glaciation cycle. The experts' median value vas 0,1 earthquakes for one glaciation cycle.

  15. Evolution of the Southern Margin of the Donbas (Ukraine) from Devonian to early Carboniferous Times.

    NARCIS (Netherlands)

    McCann, T.; Saintot, A.N.

    2003-01-01

    A Devonian-Early Carboniferous succession comprising thick clastic and carbonate sediments with interbedded volcanics was examined along the southern margin of the Donbas fold belt. Ukraine. Following initial rifting and subsidence, a continental (fluvial, lacustrine) succession was established.

  16. Carbon isotope variations in the upper Carboniferous - Permian Mallemuk Mountain Group, eastern North Greenland

    International Nuclear Information System (INIS)

    Stemmerik, L.; Magaritz, M.

    1989-01-01

    Isotope data from Late Palaeozoic limestones of the Wandel Sea Basin in eastern North Greenland show a variation of δ 13 C from 0.0 0/00 to 5.7 0/00 vs PDB. Carbonates depleted in 13 C occur in the basal part of lower Moscovian, upper Moscovian and middle Gzhelian transgressive sequences. 13 C enriched limestones occur later in the cycles. The most 13 C enriched limestones occur in the youngest (late Early Permian-early Late Permian) part of the sequence in Amdrup Land. The isotopic data is believed to represent changes in the global carbon cycle. Thus 13 C enriched carbonates correlate to periods of burial of organic carbon mostly as coal, while 13 C depleted carbonates formed as the result of erosion and oxidation of organic carbon during sea-level low stands. (author)

  17. Microfacies, Depositional environment and Sequence Stratigraphy of Upper Carboniferous- Lower Permian rocks from Ozbak-Kuh region (Zaladou Section, East Central Iran

    Directory of Open Access Journals (Sweden)

    Ali Ahmadi

    2016-01-01

    Full Text Available Zaladou section is located in Ozbak-Kuh mountains in the nourthen part of Tabas block and consist of shale, limy sandstone, limestone and dolomite. Continous relationship of Upper Carboniferous and Lower Permian deposits, is quite evident in Zaladou section. The lower boundry of this section is located on the Absheni formation of Sardar Group with disconformity surface, and upper boundry’s is covered by disconformity surface and bauxite horizon of Bagh-e-Vang formation. According to the lithological Characters and microscopic studies, tidal flat, lagoon, bar, tidal inlet and open marine sub-environment are identified for Zaladou section. Results of this study show that Zaladou section was deposited in silisiclastic-carbonate mix homoclinal ramp in late Carboniferous and in carbonate homoclinal ramp in early Permian. Field study, microfacies and analysis through the sequence led to recognition of main sequence surface, such as: sequence boundry, maximum flooding surface, marine flooding surface, system tracts and two depositional sequences.

  18. From the central Jura mountains to the molasse basin (France and Switzerland)

    Energy Technology Data Exchange (ETDEWEB)

    Sommaruga, A. [Institut de Géophysique, University of Lausanne, Bâtiment Amphipôle, Lausanne (Switzerland)

    2011-07-01

    This illustrated article discusses the geology of the area covering the Swiss Jura chain of mountains and the molasse basin which is to be found to the south-east of the mountain chain. The geological setting with the Jura Mountains and the molasse basin are described, as are the rocks to be found there. Their structures and faults are discussed in detail and their origin and formation are described. The paper presents a number of geological profiles and maps. The methods used to explore these structures are noted, which also indicated the presence of permo-carboniferous troughs in the molasse basin.

  19. From the central Jura mountains to the molasse basin (France and Switzerland)

    International Nuclear Information System (INIS)

    Sommaruga, A.

    2011-01-01

    This illustrated article discusses the geology of the area covering the Swiss Jura chain of mountains and the molasse basin which is to be found to the south-east of the mountain chain. The geological setting with the Jura Mountains and the molasse basin are described, as are the rocks to be found there. Their structures and faults are discussed in detail and their origin and formation are described. The paper presents a number of geological profiles and maps. The methods used to explore these structures are noted, which also indicated the presence of permo-carboniferous troughs in the molasse basin

  20. Concentration of gallium in the Permo-Carboniferous coals of China

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Cunliang; Qin, Shenjun; Yang, Yinchao; Li, Yanheng; Lin, Mingyue [Hebei University of Engineering, Handan (China)

    2009-10-15

    Gallium is widely used in electronic industry and its current price is about 500 US dollars per kilogram. It has been found that its contents are very high in Permo-Carboniferous coal of China. In order to look for valuable associated gallium deposits in coal, gallium contents of 177 coal samples were determined by using inductively coupled plasma-mass spectrometry (ICP-MS) and the data of 873 coal samples from Chinese Permo-Carboniferous coalfields were collected. The results show that the average gallium concentration of Chinese Permo-Carboniferous coals is 15.49{mu}g{center_dot}g{sup -1}. There are two concentration types of gallium in Chinese Permo-Carboniferous coals: one type is that gallium has enriched to an ore deposit, and another type is that gallium is locally enriched in coal seams, but has not formed a valuable associated gallium ore deposit. The gallium concentration in Chinese Permo-Carboniferous coal may have several different sources: concentration in sedimentation stage, magmatic hydrothermal inputs and low-temperature hydrothermal fluids.

  1. Geochemical characteristics of Carboniferous-Permian coal-formed gas in Bohai Bay Basin

    Energy Technology Data Exchange (ETDEWEB)

    Shipeng Huang; Fengrong Liao; Xiaoqi Wu [PetroChina, Beijing (China). Research Institute of Petroleum Exploration & Development

    2010-03-15

    Coal-formed gas reservoirs have been found in several depressions in Bohai Bay Basin. The gas was mainly generated by the Carboniferous-Permian coal measures, which are good source rocks. The exploration of coal-formed gas has a broad prospect. The main reservoirs of the coal-formed gas are Ordovician, Carboniferous-Permian, and Paleogene stratum. Coal-formed gas in the Bohai Bay Basin is chiefly composed of hydrocarbon gases. The percentage content of carbon dioxide is more than that of the nitrogen gas. The stable carbon isotope values of the hydrocarbon gases of different depressions and different reservoirs usually reversed. The reversed values of gas samples account for 52.1% of all the samples. Reversion values of the carbon isotope are mainly because of the mixing of gases from same source rocks but with different maturity. Among the three main reservoirs, coal-formed gas preserved in Paleogene stratum has the heaviest carbon isotope, the second is the gas in Carboniferous-Permian stratum, and the Ordovician gas possesses the lightest carbon isotope. Based on the analysis of the characteristics of carbon isotope of hydrocarbon gases in well Qishen-1 and the distribution of the Carboniferous-Permian coal measures, the gas of the well is derived from the high-matured Carboniferous-Permian coal measures.

  2. Quaternary glaciation of the Tashkurgan Valley, Southeast Pamir

    Science.gov (United States)

    Owen, Lewis A.; Chen, Jie; Hedrick, Kathyrn A.; Caffee, Marc W.; Robinson, Alexander C.; Schoenbohm, Lindsay M.; Yuan, Zhaode; Li, Wenqiao; Imrecke, Daniel B.; Liu, Jinfeng

    2012-07-01

    The Quaternary glacial history of Tashkurgan valley, in the transition between the Pamir and Karakoram, in Xinjiang Province, China was examined using remote sensing, field mapping, geomorphic analysis of landforms and sediments, and 10Be terrestrial cosmogenic nuclide dating. Moraines were assigned to four glacial stages: 1) the Dabudaer glacial stage that dates to the penultimate glacial cycle and/or earlier, and may represent one or more glaciations; 2) the Tashkurgan glacial stage that dates to early last glacial, most likely Marine Oxygen Isotope Stage (MIS) 4; 3) the Hangdi glacial stage that dates to MIS 2, possibly early MIS 2; and 4) the Kuzigun glacial stage that dates to the MIS 2, possibly the global Last Glacial Maximum, and is younger than the Hangdi glacial stage. Younger moraines and rock glaciers are present at the heads of tributary valleys; but these were inaccessible because they are located close to politically sensitive borders with Pakistan, Afghanistan and Tajikistan. Glaciers during the Dabudaer glacial stage advanced into the central part of the Tashkurgan valley. During the Tashkurgan glacial stages, glaciers advanced several kilometers beyond the mouths of the tributary valleys into the Tashkurgan valley. Glaciers during the Hangdi and Kuzigun glacial stages advanced just beyond the mouths of the tributary valleys. Glaciation in this part of the Himalayan-Tibetan orogen is likely strongly controlled by northern hemisphere climate oscillations, although a monsoonal influence on glaciation cannot be ruled out entirely.

  3. Biomarkers of a Low-Latitude Neoproterozoic Glaciation

    Science.gov (United States)

    Olcott, A. N.; Sessions, A. L.; Corsetti, F. A.; Kaufman, A. J.

    2005-12-01

    Neoproterozoic low-latitude glaciations are often considered times of great biologic limitation because of the hypothesized presence of thick, global sea ice. Alternatively, climate models have suggested that tropical oceans could have remained ice-free, or covered by only thin sea ice, allowing life to continue unimpeded throughout the glaciations. The analysis of organic remains from synglacial sediments provides an approach to address the debate. Here we describe molecular, isotopic, and petrographic analyses of organic rich strata (up to 3.0 percent TOC) deposited in southeastern Brazil during Neoproterozoic low-latitude glaciation ca. 700 Ma. These strata contain extractable biomarkers, including 2-α-methyl hopanes, 2,3,6-trimethylarylisoprenoids, C29-C31 hopanes, and C27-C29 steranes. The preserved biomarkers reflect the presence of a complex and productive ecosystem comprised of both aerobic and anaerobic phototrophs, heterotrophs, and eukaryotes. The biomarker data indicate euxinia extending into the photic zone, providing evidence that the oceans were strongly stratified. Significantly, the occurrence of photosynthetic cyanobacteria and green sulfur bacteria at this time indicates that sea-ice cover at this location was thin to nonexistent, and is incompatible with models for snowball Earth that envision kilometers of ice thickness.

  4. Synoptic climate change as a driver of late Quaternary glaciations in the mid-latitudes of the Southern Hemisphere

    Science.gov (United States)

    Rother, H.; Shulmeister, J.

    2006-05-01

    The relative timing of late Quaternary glacial advances in mid-latitude (40-55° S) mountain belts of the Southern Hemisphere (SH) has become a critical focus in the debate on global climate teleconnections. On the basis of glacial data from New Zealand (NZ) and southern South America it has been argued that interhemispheric synchrony or asynchrony of Quaternary glacial events is due to Northern Hemisphere (NH) forcing of SH climate through either the ocean or atmosphere systems. Here we present a glacial snow-mass balance model that demonstrates that large scale glaciation in the temperate and hyperhumid Southern Alps of New Zealand can be generated with moderate cooling. This is because the rapid conversion of precipitation from rainfall to snowfall drives massive ice accumulation at small thermal changes (1-4°C). Our model is consistent with recent paleo-environmental reconstructions showing that glacial advances in New Zealand during the Last Glacial Maximum (LGM) and the Last Glacial Interglacial Transition (LGIT) occurred under very moderate cooling. We suggest that such moderate cooling could be generated by changes in synoptic climatology, specifically through enhanced regional flow of moist westerly air masses. Our results imply that NH climate forcing may not have been the exclusive driver of Quaternary glaciations in New Zealand and that synoptic style climate variations are a better explanation for at least some late Quaternary glacial events, in particular during the LGIT (e.g. Younger Dryas and/or Antarctic Cold Reversal).

  5. Synoptic climate change as a driver of late Quaternary glaciations in the mid-latitudes of the Southern Hemisphere

    Directory of Open Access Journals (Sweden)

    H. Rother

    2006-01-01

    Full Text Available The relative timing of late Quaternary glacial advances in mid-latitude (40-55° S mountain belts of the Southern Hemisphere (SH has become a critical focus in the debate on global climate teleconnections. On the basis of glacial data from New Zealand (NZ and southern South America it has been argued that interhemispheric synchrony or asynchrony of Quaternary glacial events is due to Northern Hemisphere (NH forcing of SH climate through either the ocean or atmosphere systems. Here we present a glacial snow-mass balance model that demonstrates that large scale glaciation in the temperate and hyperhumid Southern Alps of New Zealand can be generated with moderate cooling. This is because the rapid conversion of precipitation from rainfall to snowfall drives massive ice accumulation at small thermal changes (1-4°C. Our model is consistent with recent paleo-environmental reconstructions showing that glacial advances in New Zealand during the Last Glacial Maximum (LGM and the Last Glacial Interglacial Transition (LGIT occurred under very moderate cooling. We suggest that such moderate cooling could be generated by changes in synoptic climatology, specifically through enhanced regional flow of moist westerly air masses. Our results imply that NH climate forcing may not have been the exclusive driver of Quaternary glaciations in New Zealand and that synoptic style climate variations are a better explanation for at least some late Quaternary glacial events, in particular during the LGIT (e.g. Younger Dryas and/or Antarctic Cold Reversal.

  6. Contribution of chemical and isotopic tools to the knowledge of the Carboniferous limestone aquifer - final report

    International Nuclear Information System (INIS)

    Gourcy, L.; Crastes de Paulet, F.

    2012-05-01

    Based on two sampling, analysis and interpretation campaigns, this study aimed at revealing hydro-chemical phenomena occurring within the Carboniferous and interactions between water and rock (ionic exchanges, oxido-reduction, dissolution, precipitation...), at characterizing underground flows (origins, circulation timing, mixing of different waters...), at identifying sources and at understanding phenomena related to the occurrence of high contents of sulphates (SO 4 ) in some drilling in the Carboniferous. The report presents the adopted methodology (analysis of underground and ground waters, selection of sampling points) and comments the obtained results

  7. Geological analysis and petrographic training Tarata in careers (Upper Paleozoic)-test paleoclimatic interpretation in the light of the glacial episode devono-carboniferous (Arlit region, northern Niger)

    International Nuclear Information System (INIS)

    El Hamet, Mai Ousmane

    1983-01-01

    I - Lower Carboniferous glacial Designed west of the Air (northern Niger), it consists mainly of coarse sandstone with few pebbles scattered or polygenic conglomerate matrix abundant silty-clay sandstone. The ice structures, such as eskers, kames and Pingo are very well represented, but are smaller. The glacial facies are characterized by rapid lateral variations and fall into a narrow submeridional. The small extension of these facies and the position of this region at about 50 degrees south latitude in the Carboniferous period Devono-lead to believe that these phenomena related to valley glaciers mountain, but not necessarily requiring very high altitude at this latitude. II - Formation of Tarat:1-Stratigraphy. The sedimentological and petrographic study of tarat in the quarries in the region SOMAIR Arlit shows that this training has three distinct lithostratigraphic units separated by erosive surfaces of discontinuities with a major tarat located between the middle and upper Tarat . Biostratigraphy made from pollen analysis and paleobotanical studies confirm that major lithologic discontinuity between the deposition of Lower Carboniferous and Upper Permian those with a gap in the Upper Carboniferous and Lower Permian, it will be specified by further studies.2-Paleoclimatology. The new observations in the same career and the existence of glacial phenomena mentioned above before submitting the formation of tarat, led to consider the latter assuming a palaeoenvironment periglacial hypothesis that, in light periglacial seems to reject. Indeed, many characters observed (solifluction, grooves and ridges possible, relatively fresh feldspar) can also be observed in temperate and cold at that time, the region was located approximately 40 degrees south latitude.3-Volcanism.The existence of volcanism contemporaneous with deposition of Tarat was highlighted on one hand with the study of elements vitroclastiques, other hand with the cluster analysis of zircon, the zirconium

  8. Geochemistry of marine and lacustrine bands in the Upper Carboniferous of the Netherlands

    NARCIS (Netherlands)

    Kombrink, H.; Os, B.J.H. van; Zwan, C.J. van der; Wong, Th.E.

    2008-01-01

    Geochemical studies on Upper Carboniferous marine bands showed that marked enrichment in redox-sensitive trace elements (uranium (U), vanadium (V), molybdenum (Mo)) mostly occur if they contain Goniatites. Goniatites indicate deposition in relatively distal and deep marine environments. In contrast,

  9. On two new species of marine Ostracodes in the Carboniferous of Asturias, Spain

    NARCIS (Netherlands)

    Bless, M.J.M.

    1965-01-01

    This note is the result of a preliminary investigation made in the summer of 1964. During that season the author visited the coal-mine ”Villoria” of ”Cementos Fradera S.A.” (Asturias, Spain) in order to collect specimens of Carboniferous ostracodes. Two new species of Hollinella were found and are

  10. A new biostratigraphical tool for reservoir characterisation and well correlation in permo-carboniferous sandstones

    NARCIS (Netherlands)

    Garming, J.F.L.; Cremer, H.; Verreussel, R.M.C.H.; Guasti, E.; Abbink, O.A.

    2010-01-01

    Permo-Carboniferous sandstones are important reservoir rocks for natural gas in the Southern North Sea basin. This is a mature area which makes tools for reservoir characterization and well to well correlation important for field optimalisation and ongoing exploration activities. Within the

  11. The main fish communities of the limnic Permian and Carboniferous basins of the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Zajíc, Jaroslav

    33-34, - (2006), s. 99-101. ISBN 80-210-4097-1. ISSN 1211-281X. [Paleontological Conference /7./. Brno, 19.10.2006-20.10.2006] Institutional research plan: CEZ:AV0Z30130516 Keywords : ichthyofaunae * Upper Carboniferous * Lower Permian Subject RIV: EG - Zoology

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  13. Semiplanus (Productida, Brachiopoda) from the Carboniferous limestone of Kotaki, Niigata Prefecture, central Japan

    OpenAIRE

    Ibaraki, Yousuke; Sato, Kiichi

    2013-01-01

    An Early Carboniferous large–sized productid brachiopod species, Semiplanus semiplanus (Schwetzow, 1922), is described from the Tsuchikurazawa Limestone (upper Visean–Serpukhovian), a limestone block within a Permian accretionary complex, distributed in the Kotaki area, Itoigawa City, Niigata Prefecture, central Japan. This is the first record of Semipanus species from Japan.

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

    Science.gov (United States)

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

    2016-04-01

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

  15. Geochronology of Tropical Alpine Glaciations From the Cordillera Huayhuash, Peru

    Science.gov (United States)

    Hall, S. R.; Farber, D. L.; Rodbell, D. T.; Finkel, R. C.; Ramage, J. M.; Smith, J. A.; Mark, B. G.; Seltzer, G. O.

    2004-12-01

    The Cordillera Huayhuash of the Central Peruvian Andes (10.3° S, 76.9° W) is an ideal range to study regional climate signals and variations in paleo-ice volumes. Located between the Cordillera Blanca to the north and the Junin region to the south, the range trends nearly north-south with modern glaciers confined to the high peaks (>4800 m). Cross-cutting relationships, geomorphology, and correlation with surface exposure dated moraines in the nearby Cordillera Blanca suggest the region preserves a rich record of tropical glaciation. In order to determine the glacial chronology we mapped and dated glacial features of the Jahuacocha valley (which drains the western side of the range) and two eastern drainages, the Mitococha valley, and the Carhuacocha valley. At each locality we used ASTER data, aerial photographs, and GPS to map glacial features both within main valleys and tributaries. We sampled quartz-bearing erratics on moraine crests as well as ice-polished bedrock surfaces for exposure age dating using in situ produced cosmogenic 10Be and 26Al. In the Jahuacocha valley, the greatest ice extent reached an elevation of ˜4090m and moraine crest boulders yield and age of ˜11.2 ±0.6 ka suggesting a significant late Glacial ice advance or stillstand. A younger cluster of moraines exists ˜1 km up-valley at an elevation of ˜4100m. These moraines, dated at ˜8.0 ±1.0 ka, suggest an early Holocene advance. In the Mitococha valley, a young moraine and polished bedrock dated at ˜0.2 ka and ˜11.4 ±0.4 ka respectively span the late Glacial through recent. The late Glacial features of this eastern drainage occur at an elevation of ˜4100m while the recent events occur at an elevation of ˜4380m. Our preliminary results suggest that all three valleys experienced a very similar glacial history with minor differences likely due to the variations in valley morphology. Comparing the chronology of glaciation in the Cordillaera Huayhuash with that in regions to the

  16. Mountaineering Tourism

    Directory of Open Access Journals (Sweden)

    Patrick Maher

    2016-08-01

    Full Text Available Reviewed: Mountaineering Tourism Edited by Ghazali Musa, James Higham, and Anna Thompson-Carr. Abingdon, United Kingdom: Routledge, 2015. xxvi + 358 pp. Hardcover. US$ 145.00. ISBN 978-1-138-78237-2.

  17. Contrasting neogene denudation histories of different structural regions in the transantarctic mountains rift flank constrained by cosmogenic isotope measurements

    NARCIS (Netherlands)

    Wateren, F.M. van der; Dunai, T.J.; Balen, R.T. van; Klas, W.; Verbers, A.L.L.M.; Passchier, S.; Herpers, U.

    1999-01-01

    Separate regions within the Transantarctic Mountains, the uplifted flank of the West Antarctic rift system, appear to have distinct Neogene histories of glaciation and valley downcutting. Incision of deep glacial outlet valleys occurred at different times throughout central and northern Victoria

  18. Crustaceans from bitumen clast in Carboniferous glacial diamictite extend fossil record of copepods.

    Science.gov (United States)

    Selden, Paul A; Huys, Rony; Stephenson, Michael H; Heward, Alan P; Taylor, Paul N

    2010-08-10

    Copepod crustaceans are extremely abundant but, because of their small size and fragility, they fossilize poorly. Their fossil record consists of one Cretaceous (c. 115 Ma) parasite and a few Miocene (c. 14 Ma) fossils. In this paper, we describe abundant crustacean fragments, including copepods, from a single bitumen clast in a glacial diamictite of late Carboniferous age (c. 303 Ma) from eastern Oman. Geochemistry identifies the source of the bitumen as an oilfield some 100-300 km to the southwest, which is consistent with an ice flow direction from glacial striae. The bitumen likely originated as an oil seep into a subglacial lake. This find extends the fossil record of copepods by some 188 Ma, and of free-living forms by 289 Ma. The copepods include evidence of the extant family Canthocamptidae, believed to have colonized fresh water in Pangaea during Carboniferous times.

  19. Mössbauer study of Fe mineralogy with respect to rank, type and Colombian carboniferous zone

    International Nuclear Information System (INIS)

    Caballero, F. Reyes; Martínez Ovalle, S. A.; Díaz Lagos, M.; Gómez, O. P.; Blandón, A.

    2017-01-01

    The transmission mode of Fe-57 Mössbauer spectroscopy was used to identify iron bearing minerals and establish relationships between and among these minerals and the ranks and types of various carboniferous zones in Colombia. Maceral and mineral compositions vary significantly among Colombian carboniferous zones. These variations determine some of the final characteristics and potential uses of coal, and therefore significantly contribute to defining coal quality. A comparison of spectroscopy results shows that the thermal maturity of the Colombian coals ranges from lignite to semianthracite. Similarities and differences exist with respect to conventional parameters. The coals of Córdoba and Cauca have higher sulfur contents > 2 % ash contents. Iron bearing minerals identified included pyrite, which was, found everywhere, and illite, ankerite, siderite, iron sulfates were found in particular areas. Coals from Valle del Cauca, Córdoba, Caldas and Santander are characterized by oxidation of pyrite and its transformation into ferrous or ferric sulfate.

  20. Carboniferous Granitoid Magmatism of Northern Taimyr: Results of Isotopic-Geochemical Study and Geodynamic Interpretation

    Science.gov (United States)

    Kurapov, M. Yu.; Ershova, V. B.; Makariev, A. A.; Makarieva, E. V.; Khudoley, A. K.; Luchitskaya, M. V.; Prokopiev, A. V.

    2018-03-01

    Data on the petrography, geochemistry, and isotopic geochronology of granites from the northern part of the Taimyr Peninsula are considered. The Early-Middle Carboniferous age of these rocks has been established (U-Pb, SIMS). Judging by the results of 40Ar/39Ar dating, the rocks underwent metamorphism in the Middle Permian. In geochemical and isotopic composition, the granitic rocks have much in common with evolved I-type granites. This makes it possible to specify a suprasubduction marginal continental formation setting. The existence of an active Carboniferous margin along the southern edge of the Kara Block (in presentday coordinates) corroborates the close relationship of the studied region with the continent of Baltia.

  1. Uranium minerals in Upper Carboniferous rocks in the Nowa Ruda region

    International Nuclear Information System (INIS)

    Bareja, E.

    1981-01-01

    Results of mineralogical studies on uranium in Upper Carboniferous rocks (Glinik Beds - Westphalian C - D and Ludwikowice Beds - Stephanian) in the vicinities of Nowa Ruda (Central Sudetic Depression) are presented. Uranium mineralization is here related to sandstones and polymictic conglomerates with clay and clay-carbonate cement. The major uranium-bearing horizon was found in middle part of the Glinik Beds, and some increase in uranium content - at the base of that unit. In the case of Stephanian rocks, points with uranium mineralization were found in various parts of the Ludwikowice Beds sequence: in basal conglomerate horizon and platy sandstones. Uranium minerals mainly occur in cement of sandstones and conglomerates. They were mainly identified as uranium blende and minerals of the sulfate group - zippeite and uranopilite. Mineralized uranium-bearing horizons display mineral paragenesis typical of Upper Carboniferous rocks of the Central Sudetic Depression: uranium blende, pyrite, chalcopyrite, sphalerite and galena. (author)

  2. Mössbauer study of Fe mineralogy with respect to rank, type and Colombian carboniferous zone

    Energy Technology Data Exchange (ETDEWEB)

    Caballero, F. Reyes, E-mail: carefa4@hotmail.com; Martínez Ovalle, S. A., E-mail: s.agustin.martinez@uptc.edu.co [Universidad Pedagógica y Tecnológica de Colombia, Grupo de Física Nuclear Aplicada y Simulación (Colombia); Díaz Lagos, M., E-mail: mercedes.diaz@uptc.edu.co [Universidad Pedagógica y Tecnológica de Colombia, Escuela de Ingeniería Geológica (Colombia); Gómez, O. P., E-mail: olgapatricia.gomez@uptc.edu.co [Universidad Pedagógica y Tecnológica de Colombia, Escuela de Ingeniería de Minas (Colombia); Blandón, A., E-mail: asblando@unal.edu.co [Universidad Nacional de Colombia, Departamento de Materiales y Minerales, Facultad de Minas (Colombia)

    2017-11-15

    The transmission mode of Fe-57 Mössbauer spectroscopy was used to identify iron bearing minerals and establish relationships between and among these minerals and the ranks and types of various carboniferous zones in Colombia. Maceral and mineral compositions vary significantly among Colombian carboniferous zones. These variations determine some of the final characteristics and potential uses of coal, and therefore significantly contribute to defining coal quality. A comparison of spectroscopy results shows that the thermal maturity of the Colombian coals ranges from lignite to semianthracite. Similarities and differences exist with respect to conventional parameters. The coals of Córdoba and Cauca have higher sulfur contents > 2 % ash contents. Iron bearing minerals identified included pyrite, which was, found everywhere, and illite, ankerite, siderite, iron sulfates were found in particular areas. Coals from Valle del Cauca, Córdoba, Caldas and Santander are characterized by oxidation of pyrite and its transformation into ferrous or ferric sulfate.

  3. Population genetics of the westernmost distribution of the glaciations-surviving black truffle Tuber melanosporum.

    Science.gov (United States)

    García-Cunchillos, Iván; Sánchez, Sergio; Barriuso, Juan José; Pérez-Collazos, Ernesto

    2014-04-01

    The black truffle (Tuber melanosporum Vittad.) is an important natural resource due to its relevance as a delicacy in gastronomy. Different aspects of this hypogeous fungus species have been studied, including population genetics of French and Italian distribution ranges. Although those studies include some Spanish populations, this is the first time that the genetic diversity and genetic structure of the wide geographical range of the natural Spanish populations have been analysed. To achieve this goal, 23 natural populations were sampled across the Spanish geographical distribution. ISSR technique demonstrated its reliability and capability to detect high levels of polymorphism in the species. Studied populations showed high levels of genetic diversity (h N  = 0.393, h S  = 0.678, Hs = 0.418), indicating a non threatened genetic conservation status. These high levels may be a consequence of the wide distribution range of the species, of its spore dispersion by animals, and by its evolutionary history. AMOVA analysis showed a high degree of genetic structure among populations (47.89%) and other partitions as geographical ranges. Bayesian genetic structure analyses differentiated two main Spanish groups separated by the Iberian Mountain System, and showed the genetic uniqueness of some populations. Our results suggest the survival of some of these populations during the last glaciation, the Spanish southern distribution range perhaps surviving as had occurred in France and Italy, but it is also likely that specific northern areas may have acted as a refugia for the later dispersion to other calcareous areas in the Iberian Peninsula and probably France.

  4. Zircon dating of Devonian-Carboniferous rocks from the Bombala area, New South Wales

    International Nuclear Information System (INIS)

    Sircombe, K.N.; McQueen, K.G.

    2000-01-01

    Zircons from two igneous and two sedimentary units in the Bombala area of southeastern New South Wales have been examined by the sensitive high resolution ion microprobe (SHRIMP) to establish a time frame in which to interpret these rocks. Previous studies have correlated these rocks with Late Devonian units of the south coast, solely upon the basis of stratigraphy and lithology as palaeontological evidence was absent. The two igneous units are the Hospital Porphyry and Paradise Porphyry occurring beneath the sedimentary units. Both give a Frasnian age that can be correlated with the Boyd Volcanic Complex. The sedimentary samples are from the basal and upper sections of the Rosemeath Formation, a fluvial 'redbed' consisting of conglomerate, coarse sandstone, and associated red siltstone and mudstone. Detrital zircons from the basal conglomeratic section at Kilbrechin indicate a dominant provenance from local Silurian granites and volcanics and a maximum depositional age that can be correlated with the Frasnian-Famennian Merrimbula Group. However, detrital zircons from the upper coarse sandstone section of the Rosemeath Formation at Endeavour Lookout challenge the positive correlation trend with a lack of Silurian-age grains and a presence of grains ranging from Late Devonian to Early Carboniferous in age. These results imply either that the south coast correlation is not valid for the upper sequences, or that the Merrimbula Group sequences also extend upward into the Carboniferous. The general coarseness of the Rosemeath Formation also suggests a relatively local provenance. No Early Carboniferous source is known in the immediate vicinity suggesting that Early Carboniferous igneous activity in this region of the Lachlan Orogen may have been more extensive than is currently realised. Copyright (1999) Geological Society of Australia

  5. Facies and sedimentary series in the La Camocha Carboniferous, (Gijon, NW Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Corrales, I; Flor, G; Pello, J; Peon, A

    1985-01-01

    The Carboniferous of La Camocha Mine consists mainly of terrigenous facies belonging to a fluvial-dominated delta system. Occasionally, as a consequence of avulsion, the area is abandoned by the distributary channels; it gives occasion for some quick marine transgression, the sediments of which being of carbonate character. This situation occurs in the lower part of the studied succession; the upper one is characterised only by sediments of the delta plain environments. 12 references.

  6. Revision of the Xenacanthida (Chondrichthyes : Elasmobranchii) from the Carboniferous of the British Isles

    Energy Technology Data Exchange (ETDEWEB)

    Hampe, O. [Humboldt University, Berlin (Germany)

    2003-07-01

    Xenacanthids were a very successful group of elasmobranchs that ranged from the Lower Carboniferous to the Upper Triassic. The history of discovery of the xenacanthids, which is closely connected with the history of coal prospecting in England, began with the finding of the type specimen of Xenacanthus laevissimus in the Westphalian B of the West Midlands. In this first review of British Carboniferous xenacanthids, the number of taxa, mainly erected during Victorian times, is reduced to 14 species distributed among six genera. Determinable remains are recorded from at least 96 localities in the British Isles. Unique characteristics of the Dinantian Diplodoselache suggest that the lineage to which this taxon belongs marks a dead end in xenacanthid evolution. This investigation also shows that the Pendleian Dicentrodus, formerly described as Cladodus, belongs to the xenacanthids. The occurrence of Orthacanthus cf. kounoviensis in the Pennines, also known from the German Saar-Nahe basin, the Saale depression and from Bohemia, indicates a faunal exchange between these intramontainous basins during the Carboniferous. The genus Triodus is identified from British deposits for the first time. A cladistic analysis of the xenacanthids suggests that they evolved from phoebodontid elasmobranchs. This analysis also confirms separation of the Middle Devonian Antarctilamna from a relationship with xenacanthid sharks.

  7. Fire history and climate variability during the Mid-Late Holocene in the Picos de Europa (Cantabrian Mountains, NW Spain), based on sedimentary sequence of Belbín

    Science.gov (United States)

    Ruiz-Fernández, Jesús; Nieuwendam, Alexandre; Oliva, Marc; Lopes, Vera; Cruces, Anabela; Conceição Freitas, Maria; Janeiro, Ana; López-Sáez, José Antonio; García-Hernández, Cristina

    2017-04-01

    The environmental changes during the last millennia in the Mediterranian Region (including the Cantabrian Mountains in the NW part of the Iberian Peninsula) are partially related to fire activity, generated by early human societies for grazing purposes. Fire activity has mostly been reconstructed based on the analysis of pollen, spores and other macro- and microscopic organic remains, such as charcoal particles. However, new techniques (as the analysis of micro-scale frost weathering of quartz grains), can provide further information about the magnitude and intensity of fire as a landscape modeler. The purpose of this work was to analyze a sedimentary sequence collected from Belbín depression in the Western Massif of the Picos de Europa (Cantabrian Mountains, NW Spain) by using an innovative multi-proxy approach, in order to reconstruct the fire history in this area. The Picos de Europa Mountains constitute the highest and most extensive massif in the Cantabrian Mountains. This area encloses three different massifs separated by deep gorges carved by four rivers (Dobra, Cares, Duje and Deva). The Western Massif is the largest of the three units (137 km2). The Picos de Europa are essentially composed by Carboniferous limestones. This mountain area was heavily glaciated during the Last Glaciation, though the post-glacial environmental evolution is still poorly understood. Within the Western Massif, the mid-altitude area of Belbín is a karstic depression dammed by a lateral moraine generated by Enol Glacier during the Last Glaciation. Between 23 and 8 ky cal BP this depression was a lake that became progressively infilled with sediments, and nowadays it is occupied by grasslands (Ruiz-Fernández et al., 2016). In order to study the environmental changes during the Mid-Late Holocene in this massif, a 182 cm-long sequence was retrieved in the Belbín area. The core was subsampled every centimeter in the top most superficial 60 cm. The laboratory analyses were: 1

  8. Holocene glaciation of the central Sierra Nevada, California

    Science.gov (United States)

    Bowerman, Nicole D.; Clark, Douglas H.

    2011-05-01

    Sediment cores from two bedrock-dammed lakes in North Fork Big Pine Creek, Sierra Nevada, California, preserve the most detailed and complete record of Holocene glaciation yet recovered in the region. The lakes are fed by outwash from the Palisade Glacier, the largest (˜1.3 km 2) and presumably longest-lived glacier in the range, and capture essentially all of the rock flour it produces. Distinct late-Holocene (Matthes) and late-Pleistocene (Recess Peak) moraines lie between the modern glacier and the lakes. The lakes have therefore received continuous sedimentation from the basin since the retreat of the Tioga glacier (Last Glacial Maximum) and capture rock flour related to all post-LGM advances. A total of eight long cores (up to 5.5 m sediment depth) and one short surface sediment short core preserve a coherent record of fluctuating rock flour flux to the lakes through the Holocene. Age constraints on rock flour spikes in First and Second lakes based on 31 14C-dated macrofossils indicate Holocene glaciation began ˜3200 cal yr B P, followed by a possible glacier maximum at ˜2800 cal yr B P and four distinct glacier maxima at ˜2200, ˜1600, ˜700 and ˜250-170 cal yr. B.P., the most recent maximum being the largest. Reconstruction of the equilibrium-line altitudes (ELA) associated with each distinct advance recorded in the moraines (Recess Peak, Matthes, and modern) indicates ELA depressions (relative to modern) of ˜250 m and 90 m for Recess Peak and Matthes advances, respectively. These differences represent decreases in summer temperatures of 1.7-2.8 °C (Recess Peak) and 0.2-2° (Matthes), and increases in winter precipitation of 22-34 cm snow water equivalent (s.w.e.) (Recess Peak) and 3-26 cm s.w.e. (Matthes) compared to modern conditions. Although small, these changes are significant and similar to those noted in the Cascade Range to the north, and represent a significant departure from historical climate trends in the region.

  9. Understanding and modelling Neo-proterozoic glaciations and their associated phenomena

    International Nuclear Information System (INIS)

    Le Hir, Guillaume

    2007-01-01

    The objective of this research thesis is to provide a consistent image of extreme glaciations which occurred during the Neo-proterozoic era. By using climate and carbon cycle models (or model of bio-geochemical cycles), the author aims at answering various scientific questions raised by the Snowball Earth hypothesis. After a description of the main geological features which characterize the Proterozoic, scientific problems are presented. The author then reports the study of carbon cycle during glaciation in order to understand its operation. Based on this constraint, a consistent scenario of exit from glaciation is defined. The physical-chemical evolution of the ocean during and after a global glaciation is then quantified in order to assess its potential effects on the environment and on the Precambrian biosphere. The last part focuses on the post-glacial evolution to establish the delay for a return to equilibrium of climate after such an extreme event [fr

  10. Saline lakes of the glaciated Northern Great Plains

    Science.gov (United States)

    Mushet, David M.

    2011-01-01

    Unless you have flown over the region or seen aerial photographs, it is hard to grasp the scale of the millions of lakes and wetlands that dot the prairie landscape of the glaciated Northern Great Plains (Figure 1). This region of abundant aquatic habitats within a grassland matrix provides for the needs of a wide diversity of wildlife species and has appropriately been deemed the "duck factory of North America." While the sheer number of lakes and wetlands within this area of the Northern Great Plains can be truly awe-inspiring, their diversity in terms of the chemical composition of their water adds an equally important component supporting biotic diversity and productivity. Water within these lakes and wetlands can range from extremely fresh with salinities approaching that of rainwater to hypersaline with salinity ten times greater than that of seawater. Additionally, while variation in salinity among these water bodies can be great, the ionic composition of lakes and wetlands with similar salinities can vary markedly, influencing the overall spatial and temporal diversity of the region's biota.

  11. Seabed geodiversity in a glaciated shelf area, the Baltic Sea

    Science.gov (United States)

    Kaskela, Anu Marii; Kotilainen, Aarno Tapio

    2017-10-01

    Geodiversity describes the heterogeneity of the physical terrain. We have performed basin-wide geodiversity analysis on a glaciated epicontinental seabed to assess geodiversity measures and patterns, locate areas with high geodiversity, and draw conclusions on contributing processes. Geodiversity quantification is a rather new topic and is mainly practiced in land areas. We applied geodiversity methods developed for terrestrial studies to a seabed environment. Three geodiversity parameters, including the richness, patchiness, and geodiversity index, of the Baltic Sea were assessed in a GIS environment based on broad-scale datasets on seabed substrates, structures, and bedrock. A set of environmental and geological variables, which were considered to reflect geological processes under seabed conditions, were compared with the geodiversity to identify some of its drivers. We observed differences in the geodiversity levels of the Baltic subbasins, which are mainly due to basement type/bedrock, roughness, shore density, and glacier-derived processes. The geodiversity of the Baltic Sea generally increases from South to North and from open-sea to high-shore density areas (archipelagos). Crystalline bedrock areas provide more diverse seabed environments than sedimentary rock areas. The analysis helps to inform scientists, marine spatial planners, and managers about abiotic conservation values, the dynamics of the seabed environment, and potential areas with elevated biodiversity.

  12. Groundwater flow and transport modelling during a glaciation period

    International Nuclear Information System (INIS)

    Jaquet, O.; Siegel, P.

    2003-01-01

    Subsequent to earlier work, SKB has decided to carry out additional hydrogeological modelling studies related to glaciation effects at Aespoe. In particular, sub glacial groundwater flow and the impact assessment on a repository require further studies. As compared to the previous model, the domain geometry and processes involved remain identical, but this time, numerical calculations are performed with the NAMMU package (version 7.1.1) using a finite element formulation. Modified assumptions corresponding to specific boundary conditions are implemented and additional variations of the base case are simulated. The objectives of the study are based on the technical specifications established by SKB. The main objectives may be summarised as follows: Enhancement of the understanding of sub glacial groundwater flow due to basal ice melting. Evaluation of the impact of sub glacial roundwater flow on a repository with respect to its position to the ice margin of the glacier. Assessment of the feasibility of performing large 3D simulations of density-driven flow induced by variable salinity of the groundwater using the NAMMU package. The report begins with an account of the modelling approach applied. Then, the results of the different cases simulated are described, analysed and interpreted in detail. Finally, conclusions are drawn up together with some recommendations related to potential modelling issues for the future. The objectives proposed for the groundwater flow and transport modelling for period of glaciation have been met: The results have shown the importance of the ice tunnels in governing sub glacial groundwater flow due to basal ice melting. The influence of the ice tunnels on the salinity distribution is significant as is their impact on the flow trajectories and, hence, on the resulting travel times. The results of simulation S0 have revealed that no steady-state flow conditions are reached. Due to the chosen salt boundary conditions, salt will continue to

  13. The Carboniferous - Permian basins of Central and Western Bohemia, the Krkonoše Mt. foreland and the Bohemian Massif, Czech Republic : part I

    Czech Academy of Sciences Publication Activity Database

    Opluštil, S.; Martínek, K.; Lojka, R.; Rosenau, N.; Zajíc, Jaroslav; Šimůnek, Z.; Drábková, J.; Štamberg, S.

    2014-01-01

    Roč. 46, č. 1 (2014), s. 14-54 ISSN 1433-1284. [Field Meeting on Carboniferous and Permian Nonmarine – Marine Correlation. Freiberg, 21.07.2014-27.07.2014] Institutional support: RVO:67985831 Keywords : Carboniferous * Permian * excursion guide Subject RIV: DB - Geology ; Mineralogy

  14. ANALYZING THE CLASSIC METHODS OF ORGANIZING THE ADMINISTRATION ACCOUNTACY USED IN THE CARBONIFEROUS MINING INDUSTRY

    Directory of Open Access Journals (Sweden)

    PALIU-POPA Lucia

    2009-12-01

    Full Text Available Information regarding production costs occupy a central slot, determined by their implications regarding the present and future evolution of a company. The value of information regarding the cost of production justifies its use both in decisions regarding the current activity and in the company’s future strategy. The efficient organization of economic activity in the carboniferous mining industry imposes a constant improvement of management methods, which also implies a reconsideration of administration accountancy methods and cost control, which have to become capable of offering information that can be compatible to the requirements for an efficient management of the production process, in a market economy.

  15. Population genetic structure and demographic history of the freshwater crab Potamon elbursi (Brachyura: Potamidae) from the Alborz Mountains in northern Iran

    OpenAIRE

    Alireza Keikhosravi; Sara Fratini; Christoph D. Schubart

    2015-01-01

    Hydrographically separated populations of the freshwater crab Potamon elbursi Pretzmann, 1976 were genetically investigated to assess their local diversity and to reconstruct the possible role of Quaternary glaciations in shaping current diversity in the Alborz Mountains, northern Iran. A total of 61 specimens from six rivers were collected from the two different drainage systems of the Alborz Mountains, Namak Lake and the South Caspian watershed. A comparative analysis of a partial sequence ...

  16. Late Quaternary glaciation history of monsoon-dominated Dingad basin, central Himalaya, India

    Science.gov (United States)

    Shukla, Tanuj; Mehta, Manish; Jaiswal, Manoj K.; Srivastava, Pradeep; Dobhal, D. P.; Nainwal, H. C.; Singh, Atul K.

    2018-02-01

    The study presents the Late Quaternary glaciation history of monsoon-dominated Dokriani Glacier valley, Dingad basin, central Himalaya, India. The basin is tested for the mechanism of landforms preservation in high relief and abundant precipitation regimes of the Higher Himalaya. Field geomorphology and remote sensing data, supported by Optical Stimulated Luminescence (OSL) dating enabled identification of five major glacial events of decreasing magnitude. The oldest glacial stage, Dokriani Glacial Stage I (DGS-I), extended down to ∼8 km (2883 m asl) from present-day snout (3965 m asl) followed by other four glaciations events viz. DGS-II, DGS-III, DGS-IV and DGS-V terminating at ∼3211, 3445, 3648 and ∼3733 m asl respectively. The DGS-I glaciation (∼25-∼22 ka BP) occurred during early Marine Isotope Stage (MIS) -2, characterized as Last Glacial Maximum (LGM) extension of the valley. Similarly, DGS-II stage (∼14-∼11 ka BP) represents the global cool and dry Older Dryas and Younger Dryas event glaciation. The DGS-III glaciation (∼8 ka BP) coincides with early Holocene 8.2 ka cooling event, the DGS-IV glaciations (∼4-3.7 ka BP) corresponds to 4.2 ka cool and drier event, DGS-V (∼2.7-∼1 ka BP) represents the cool and moist late Holocene glacial advancement of the valley. This study suggests that the Dokriani Glacier valley responded to the global lowering of temperature and variable precipitation conditions. This study also highlights the close correlation between the monsoon-dominated valley glaciations and Northern Hemisphere cooling events influenced by North Atlantic climate.

  17. Seasonal changes in Fe along a glaciated Greenlandic fjord.

    Directory of Open Access Journals (Sweden)

    Mark James Hopwood

    2016-03-01

    Full Text Available Greenland’s ice sheet is the second largest on Earth, and is under threat from a warming Arctic climate. An increase in freshwater discharge from Greenland has the potential to strongly influence the composition of adjacent water masses with the largest impact on marine ecosystems likely to be found within the glaciated fjords. Here we demonstrate that physical and chemical estuarine processes within a large Greenlandic fjord are critical factors in determining the fate of meltwater derived nutrients and particles, especially for non-conservative elements such as Fe. Concentrations of Fe and macronutrients in surface waters along Godthåbsfjord, a southwest Greenlandic fjord with freshwater input from 6 glaciers, changed markedly between the onset and peak of the meltwater season due to the development of a thin (<10 m, outflowing, low-salinity surface layer. Dissolved (<0.2 µm Fe concentrations in meltwater entering Godthåbsfjord (200 nM, in freshly melted glacial ice (mean 38 nM and in surface waters close to a land terminating glacial system (80 nM all indicated high Fe inputs into the fjord in summer. Total dissolvable (unfiltered at pH <2.0 Fe was similarly high with concentrations always in excess of 100 nM throughout the fjord and reaching up to 5.0 µM close to glacial outflows in summer. Yet, despite the large seasonal freshwater influx into the fjord, Fe concentrations near the fjord mouth in the out-flowing surface layer were similar in summer to those measured before the meltwater season. Furthermore, turbidity profiles indicated that sub-glacial particulate Fe inputs may not actually mix into the outflowing surface layer of this fjord. Emphasis has previously been placed on the possibility of increased Fe export from Greenland as meltwater fluxes increase. Here we suggest that in-fjord processes may be effective at removing Fe from surface waters before it can be exported to coastal seas.

  18. Early Carboniferous ammonoid faunas and stratigraphy of the Montagne Noire (France

    Directory of Open Access Journals (Sweden)

    D. Korn

    2007-08-01

    Full Text Available The early Carboniferous (Mississippian sedimentary succession of the Montagne Noire is subdivided into three major lithostratigraphic units, in ascending order the Montagne Noire Griotte Group (Devonian to Early Tournaisian, the Tournaisian to Viséan Saint-Nazaire Group (with the Lydiennes, Faugères, Colonnes, and Puech Capel Formations, the latter new, and the Laurens Flysch Group (late Viséan. The ammonoid assemblages in these rock units are reviewed. A total of 29 Early Carboniferous ammonoid taxa at species level are determined. The new genus Nigrocyclus n. gen., and the new species Gattendorfia nazairensis n. sp., Globimitoceras albaillei n. sp., and Neogoniatites canovasi n. sp. are described. Die unterkarbonische Abfolge von Sedimentgesteinen in der Montagne Noire wird in drei lithostratigraphische Einheiten untergliedert, von unten nach oben die Montagne Noire Griotte Gruppe (Oberdevon bis Untertournai, die Saint-Nazaire Gruppe des Tournaisium und Viséum (mit den Lydiennes Faugères, Colonnes und Puech Capel Formationen, von denen die letzte neu ist, und der Laurens Flysch Gruppe (Oberviséum. Die Ammonoideen-Vergesellschaftungen in diesen Gesteinen werden revidiert. Insgesamt werden 29 unterkarbonische Ammonoideen-Taxa auf Artebene aufgeführt; neu beschrieben werden die Gattung Nigrocyclus n. gen. sowie die Arten Gattendorfia nazairensis n. sp., Globimitoceras albaillei n. sp. und Neogoniatites canovasi n. sp. doi:10.1002/mmng.200700002

  19. Age of the last glaciation of Vestfold Hills and significance for sea level change

    International Nuclear Information System (INIS)

    Gore, D.B.; Colhoun, E.A.

    1998-01-01

    The Vestfold Hills form the second largest deglaciated oasis area in East Antarctica. The last time that the oasis was submerged by the East Antarctic ice sheet as it extended onto the continental shelf has been termed the ''Vestfold Glaciation'' (Adamson and Pickard 1986). To date the Vestfold Glaciation has been assumed to correlate with the late Wisconsin Glaciation on the basis of Holocene radiocarbon dates obtained from marine deposits in the inlets and from derived sediments ice-proximal to the margin of the Sorsdal Glacier (Adamson and Pickard 1986; Fitsimons and Dormack 1993). Radiocarbon dating of shell fragments from Vestfold till deposits distributed throughout the southern and seaward parts of the oasis have given assays from 31.1 to .43.7k yr BP. If the assays represent true ages of the time of growth of the marine shells then it would appear that the Vestfold Glaciation ice expansion onto the continental shelf post-dates 31 k yr and the glaciation is equivalent to the late Wisconsin. Similarly, if the range of assays represents true ages then the fiords must have been occupied by the sea during late middle Wisconsin time, presumably when the continental margin was isostatically depressed below present level. There is, however, the possibility that the assays are minimal, and being derived into till from older marine deposits they could have true greater and mixed ages. This alternative is being explored

  20. Permo-Carboniferous volcanism in late Variscan continental basins of the Bohemian Massif (Czech Republic): geochemical characteristic

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Pešek, J.; Štěpánková-Svobodová, Jana; Bosák, Pavel; Lloyd, F. E.; Seckendorff, von, V.; Lang, Miloš; Novák, Jiří Karel

    2006-01-01

    Roč. 66, č. 1 (2006), s. 37-56 ISSN 0009-2819 R&D Projects: GA AV ČR(CZ) IAA3013903 Institutional research plan: CEZ:AV0Z30130516 Keywords : Permo-Carboniferous * volcanics * continental basin * Bohemian Massif * underplating * crustal anatexis * Sr-Nd isotopes Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.824, year: 2006

  1. Climatic and biotic changes around the Carboniferous/Permian boundary recorded in the continental basins of the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Opluštil, S.; Šimůnek, Z.; Zajíc, Jaroslav; Mencl, V.

    2013-01-01

    Roč. 119, č. 1 (2013), s. 114-151 ISSN 0166-5162 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : biotic change * Bohemian Massif * Carboniferous-Permian transition * continental basin Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.313, year: 2013

  2. Quaternary glaciation of the Lato Massif, Zanskar Range of the NW Himalaya

    Science.gov (United States)

    Orr, Elizabeth N.; Owen, Lewis A.; Saha, Sourav; Caffee, Marc W.; Murari, Madhav K.

    2018-03-01

    The glacial chronostratigraphy and history of the Lato Massif of Zanskar northern India is defined for the first time using geomorphic mapping and 10Be surface exposure dating. Three local glacial stages, the Lato, Shiyul and Kyambu, are dated to 244-49, 25-15 and 3.4-0.2 ka, respectively. The Lato glacial stage was the most extensive period of glaciation, characterized by expanded ice caps with glaciers advancing to ∼16 km from their present position. Large till deposits are associated with this glacial stage, which represent a time of heightened glacial erosion and localized incision, and increased rates of sediment transfer and deposition. The glacial style transitioned to entrenched valley glaciation during the Shiyul glacial stage. Hummocky moraine complexes reflecting fluctuating glacier margins characterize this glaciation. Glaciers have been confined to the cirques and headwalls of the massif during and since the Kyambu glacial stage. Equilibrium-line altitude (ELA) reconstructions help define the shifts in glaciation over time, with ELA depressions changing from 470 ± 140, 270 ± 80 to 100 ± 30 m for the Lato, Shiyul and Kyambu glacial stages, respectively. The change of glacial style during the latter part of the Quaternary is similar to other regions of the Transhimalaya and Tibet suggesting that this pattern of glaciation may reflect regional climatic forcing. The evolution of the Lato Massif from an isolated alpine plateau to a steeply incised massif over the last several glacial-interglacial cycles may have also influenced the shifts from ice cap to valley glaciation.

  3. Sensitivity of glaciation in the arid subtropical Andes to changes in temperature, precipitation, and solar radiation

    Science.gov (United States)

    Vargo, L. J.; Galewsky, J.; Rupper, S.; Ward, D. J.

    2018-04-01

    The subtropical Andes (18.5-27 °S) have been glaciated in the past, but are presently glacier-free. We use idealized model experiments to quantify glacier sensitivity to changes in climate in order to investigate the climatic drivers of past glaciations. We quantify the equilibrium line altitude (ELA) sensitivity (the change in ELA per change in climate) to temperature, precipitation, and shortwave radiation for three distinct climatic regions in the subtropical Andes. We find that in the western cordillera, where conditions are hyper-arid with the highest solar radiation on Earth, ELA sensitivity is as high as 34 m per % increase in precipitation, and 70 m per % decrease in shortwave radiation. This is compared with the eastern cordillera, where precipitation is the highest of the three regions, and ELA sensitivity is only 10 m per % increase in precipitation, and 25 m per % decrease in shortwave radiation. The high ELA sensitivity to shortwave radiation highlights the influence of radiation on mass balance of high elevation and low-latitude glaciers. We also consider these quantified ELA sensitivities in context of previously dated glacial deposits from the regions. Our results suggest that glaciation of the humid eastern cordillera was driven primarily by lower temperatures, while glaciations of the arid Altiplano and western cordillera were also influenced by increases in precipitation and decreases in shortwave radiation. Using paleoclimate records from the timing of glaciation, we find that glaciation of the hyper-arid western cordillera can be explained by precipitation increases of 90-160% (1.9-2.6× higher than modern), in conjunction with associated decreases in shortwave radiation of 7-12% and in temperature of 3.5 °C.

  4. Carboniferous bioconstructions of the Bechar Basin, Algerian Sahara: Sedimentology, diagenesis, and petroleum potential. Les bioconstructions carboniferes du Bassin de Bechar, Sahara algerien: Sedimentologie, diagenese et potentiel petrolifere

    Energy Technology Data Exchange (ETDEWEB)

    Madi, A.

    1994-01-01

    Carbonate massifs which surface on the northwest of the Bechar Basin in the Algerian Sahara are studied, in particular the lithostratigraphic section of the upper Visean of the Grand Erg Occidental. The latter corresponds to a succession of 13 shallowing-upward parasequences. An ideal parasequence comprises a massive biohermal assemblage, constructed by the association of Fenestelles and sponges, buried under strata of crinoidal and/or oolithic grainstones. The vertical distribution of the microflora within the facies translates into a zonation as function of depth. An idealized ecological succession formed from seven benthic assemblages is proposed. Diagenetic analysis of the studied sequences has revealed nine diagenetic phases corresponding to six calcitic cements, two dolomitization phases, and one of silicification. Most of these diagenetic events were produced in medium to deep burial, after 650 m. The stratified oolithic-crinoidal carbonates could have served as reservoir rocks if trapping conditions were present. A hypothesis has been formed according to which the porous strata formed natural conduits on a regional scale and three trapping possibilities are proposed. These models, which integrate all the parameters which influence the existence of a petroleum deposit, could contribute to the establishment of an exploration strategy for the Bechar Basin Carboniferous carbonate strata. 146 refs., 61 figs., 29 tabs.

  5. Foraminiferal-based paleobiogeographic reconstructions in the Carboniferous of Iran and its implications for the Neo-Tethys opening time: a synthesis

    International Nuclear Information System (INIS)

    Arefifard, S.

    2017-01-01

    The biogeographic distribution of foraminifers and their belonging to either the southern or northern margins of the Paleo-Tethys are used here for paleogeographic reconstructions of Iran during the Carboniferous. Lower Carboniferous foraminiferal assemblages from northern and central Iran show a cosmopolitan character and affinities to both the southern and northern borders of the Paleo-Tethys. Hence, in the Early Carboniferous Iran occupied an intermediate southern latitude position, forming part of Gondwana. This conclusion is consistent with the Late Ordovician to Early Carboniferous drift history of Iran based on paleomagnetic data. In the Late Carboniferous, the foraminiferal affinities of northern and central Iran with the northern part of Paleo-Tethys suggest that Iran separated from Gondwana and moved northwards to a lower latitude. This separation is also evidenced by the Upper Carboniferous coal-bearing sandstones of the Sardar Formation and sandstones with high degree of chemical weathering, which would indicate warm and humid conditions. Considering the composition of foraminiferal fauna along with the evidence of magmatic activities in northwest Iran, it can be inferred that the commencement of the Neo-Tethys opening and continental break-up in Iran occurred sometime in the Late Carboniferous, which contradicts the previous claims that the separation of Iran from Gondwana occurred in Permian and/or Triassic times.

  6. Foraminiferal-based paleobiogeographic reconstructions in the Carboniferous of Iran and its implications for the Neo-Tethys opening time: a synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Arefifard, S.

    2017-11-01

    The biogeographic distribution of foraminifers and their belonging to either the southern or northern margins of the Paleo-Tethys are used here for paleogeographic reconstructions of Iran during the Carboniferous. Lower Carboniferous foraminiferal assemblages from northern and central Iran show a cosmopolitan character and affinities to both the southern and northern borders of the Paleo-Tethys. Hence, in the Early Carboniferous Iran occupied an intermediate southern latitude position, forming part of Gondwana. This conclusion is consistent with the Late Ordovician to Early Carboniferous drift history of Iran based on paleomagnetic data. In the Late Carboniferous, the foraminiferal affinities of northern and central Iran with the northern part of Paleo-Tethys suggest that Iran separated from Gondwana and moved northwards to a lower latitude. This separation is also evidenced by the Upper Carboniferous coal-bearing sandstones of the Sardar Formation and sandstones with high degree of chemical weathering, which would indicate warm and humid conditions. Considering the composition of foraminiferal fauna along with the evidence of magmatic activities in northwest Iran, it can be inferred that the commencement of the Neo-Tethys opening and continental break-up in Iran occurred sometime in the Late Carboniferous, which contradicts the previous claims that the separation of Iran from Gondwana occurred in Permian and/or Triassic times.

  7. Simulating the impact of glaciations on continental groundwater flow systems: 2. Model application to the Wisconsinian glaciation over the Canadian landscape

    Science.gov (United States)

    Lemieux, J.-M.; Sudicky, E. A.; Peltier, W. R.; Tarasov, L.

    2008-09-01

    A 3-D groundwater flow and brine transport numerical model of the entire Canadian landscape up to a depth of 10 km is constructed in order to capture the impacts of the Wisconsinian glaciation on the continental groundwater flow system. The numerical development of the model is presented in the companion paper of Lemieux et al. (2008b). Although the scale of the model prevents the use of a detailed geological model, commonly occurring geological materials that exhibit relatively consistent hydrogeological properties over the continent justify the simplifications while still allowing the capture of large-scale flow system trends. The model includes key processes pertaining to coupled groundwater flow and glaciation modeling, such a density-dependent (i.e., brine) flow, hydromechanical loading, subglacial infiltration, isostasy, and permafrost development. The surface boundary conditions are specified with the results of a glacial system model. The significant impact of the ice sheet on groundwater flow is evident by increases in the hydraulic head values below the ice sheet by as much as 3000 m down to a depth of 1.5 km into the subsurface. Results also indicate that the groundwater flow system after glaciation did not fully revert to its initial condition and that it is still recovering from the glaciation perturbation. This suggests that the current groundwater flow system cannot be interpreted solely on the basis of present-day boundary conditions and it is likely that several thousands of years of additional equilibration time will be necessary for the system to reach a new quasi-steady state. Finally, we find permafrost to have a large impact on the rate of dissipation of high hydraulic heads that build at depth and capturing its accurate distribution is important to explain the current hydraulic head distribution across the Canadian landscape.

  8. Late Carboniferous remagnetisation of Palaeozoic rocks in the NE Rhenish Massif, Germany

    Science.gov (United States)

    Zwing, A.; Bachtadse, V.; Soffel, H. C.

    During stepwise thermal and alternating field demagnetisation experiments on Devonian and Lower Carboniferous carbonate and clastic rocks from the north-eastern part of the Rhenish Massif, Germany, three components of magnetisation (A, B, C) are identified. Component A is a recent viscous overprint that parallels the local present day geomagnetic field. Component B is mainly observed from 260 up to 550 °C during thermal demagnetisation and is carried by magnetite. In two localities, where red siltstones and red carbonate rocks were sampled, component B is stable up to 670 °C, indicating the presence of hematite. Three clusters of in situ B directions can be identified, which are controlled by the tectonic position of the sampling areas. These are from NW to SE: the Remscheid anticline (RA), the Lüdenscheid syncline (LS) and the Attendorn and Wittgenstein synclines (AS/WS). Standard and inclination-only fold tests, using parametric resampling, yield optimal statistical parameters at increasing amounts of untilting ranging from 0% in the South up to 57% in the North of the NE Rhenish Massif. Despite the variations in optimal untilting, the resulting site mean directions of component B do not differ significantly in inclination. These results are interpreted to reflect the acquisition of magnetisation during progressive northward migration of the deformation front in Late Carboniferous times. The resulting palaeolatitudes (RA: 1°S +2°-3°; LS: 2°S +3°-2°; AS/WS: 1°S +3°-4°) are in good agreement with the predicted position of the sampling area in the Late Carboniferous, as derived from a published Apparent Polar Wander Path for Baltica and Laurentia. The unblocking temperature spectra and the synfolding nature of B yield strong evidence that chemical processes, possibly driven by fluid migration during orogenesis, caused this remagnetisation. A third component C was observed in zones of tight folding with steeply dipping to overturned bedding planes and is

  9. 36Chlorine exposure dating of a terminal moraine in the Galicica Mountains, Macedonia

    Science.gov (United States)

    Gromig, R.; Mechernich, S.; Ribolini, A.; Dunai, T. J.; Wagner, B.

    2015-12-01

    The glaciation history of the Balkan Peninsula is subject of research since the late 19th century. To date, only a few moraines on the Balkan Peninsula are dated, mainly using 10Be exposure dating applied on quartz bearing rocks. Since large parts of the Balkan Peninsula mountains are composed of carbonatic rocks, absolute age dating is restricted to 36Cl exposure dating, which, to date, was not conducted in this region yet. So far, an absolute chronological control in limestone-dominated areas is limited to U-series minimum ages of calcitic cements. In order to obtain more information about the timing of the glaciation history on the Balkan Peninsula, we investigated a terminal moraine in a NNE-facing cirque in the Galicica Mountains (40°56´N, 20°49´E) in the Former Yugoslav Republic of Macedonia. The cirque comprises a series of nested moraine ridges at the base of the cirque wall, with the largest one being sampled. Samples from five limestone boulders in crest position (≈ 2050 m a.s.l.) were taken and pre-treated for AMS measurement at the University of Cologne. Three preliminary ages point to a moraine formation in the course of a late Pleistocene glaciation, either Last Glacial Maximum or Younger Dryas. The data were discussed concerning corrections for topographic shielding, snow cover, inheritance, and erosion. However, five AMS re-measurements are currently in progress in order to refine the correlation of the moraine formation to a specific glacial period. The resulting ages will be compared to sediments of the adjacent Lakes Ohrid and Prespa, which represent valuable climatic and environmental archives. Several studies on these sediments were carried out in order to reconstruct relative changes in temperature and moisture availability. Moreover, the inferred moraine formation ages will be compared to glaciation reconstructions of other mountainous regions on the Balkan Peninsula to improve the knowledge on past climatic conditions.

  10. Use of {sup 10}Be exposure ages and Schmidt hammer data for correlation of moraines in the Krkonose Mountains, Poland/Czech Republic

    Energy Technology Data Exchange (ETDEWEB)

    Engel, Zbynek; Krizek, Marek [Charles Univ., Prague (Czech Republic). Dept. of Physical Geography and Geoecology; Traczyk, Andrzej [Wroclaw Univ. (Poland). Dept. of Geomorphology; Braucher, Regis [CEREGE, Aix-en-Provence (France); Woronko, Barbara [Warsaw Univ. (Poland). Dept. of Geography and Regional Development

    2011-06-15

    Exposure ages and relative-age data are presented from eight sites in the Lomnica and Lomniczka valleys to provide essential information for reconstructing local glaciation chronology. A combination of {sup 10}Be exposure ages and Schmidt hammer data obtained for moraines indicate relatively short period of glacier accumulation lasting from 17.0{+-}0.4 ka to 13.6{+-}0.9 ka. Exposure age of 8.4{+-}0.3 ka measured on the lowermost section of the Lomnica cirque headwall further confirms the view of glacier preservation in favourable sites until the beginning of the Holocene. A comparison of the obtained chronological data with timing of mountain glaciation in the nearby Upa Valley is used to propose the first correlative model of Late Quaternary glaciation in the eastern part of the Krkonose Mountains. The correlation implies that the lowermost preserved moraines originated during the local maximum of the last glaciation whereas recessional moraines were deposited until the Lateglacial period. A subsequent melting of glaciers terminated at the beginning of the Holocene. The implications of the model are discussed and further investigations are suggested to extend its validity to the whole mountain area. (orig.)

  11. STRATIGRAPHY AND FUSULINIDS OF THE MOSCOVIAN STAGE (MIDDLE CARBONIFEROUS IN THE SOUTHWESTERN DARVAZ (PAMIR

    Directory of Open Access Journals (Sweden)

    ERNST JA. LEVEN

    1998-03-01

    Full Text Available A refined subdivision, based on fusulinids, of the Moscovian stage in southwestern Darvaz is proposed. Seven local zones, three in the Lower Moscovian substage and four in the Upper Moscovian substage were established, based on investigations of three stratigraphic sections. The zones were correlated with those of the Eastern European and Middle Asian stratigraphic schemes. One hundred and forty-three species and subspecies, which belong to 29 genera and 13 families of fusulinids, were identified in the Middle Carboniferous of Darvaz. Among them, one genus (Undatafusulina and 16 species, i.e. Taitzehoella compacta, Ovatella panjensis, Aljutovella darvasica, Undatafusulina asiatica, Citronites panjensis, C. reticulatus, Beedeina darvasica, B. dutkevichi, Putrella admiranda, Hemifusulina orientalis, Fusulinella (Moellerites subundulata, F. (M. jucunda, F. (M. orientalis, F.(Fusulinella crassitectoria, F. (F. bogushi, and F. (F. pamirensis are new. 

  12. Stratigraphy and palynology of the Lower Carboniferous Sortebakker Formation, Wandel Sea Basin, eastern North Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Dalhoff, F.; Stemmerik, L. [Geological Survey of Denmark and Greenland, Copenhagen (Denmark); Vigran, J.O. [IKU Petroleum Research, Trondheim (Norway)

    2000-07-01

    Two palynological assemblages of Early Carboniferous age have been recorded from the upper parts of the non-marine, fluvial-dominated Sortebakker Formation in the Wandel Sea Basin. The stratigraphically lower assemblage includes poorly preserved Cingulizonates spp., Densosporites spp., Lycospora spp. and Schulzospora spp. whereas the upper assemblage contains a more diversified microflora including the stratigraphically important Tripartites distinctus, Potoniespores delicatus and Savitrisporites spp. The microflora enables correlation and dating of the succession to the late Visean Perotrilites tessellatus - Schulzospora campyloptera (TC) and Raistrickia nigra - Triquitrites marginatus (NM) miospore Biozones of western Europe. The depositional facies correspond to those seen in time equivalent deposits from East Greenland, Svalbard, Bjoernoeya and the Barents Sea. (au)

  13. On the genesis of the uranium occurrence in the carboniferous sediments, wadi Intahahah area, southwest Libya

    International Nuclear Information System (INIS)

    Assaf, H.S.

    1988-01-01

    In the course of covering the southwestern part of Libya by a systematic airborne radiometric survey, a significant group of anomalies was detected in the carboniferous sediments. Ground verification of these anomalies disclosed the confinement of these anomalies to the limestone and sandstone beds of the Assedjefar Formation assigned to visean-namurian age. Uranium content as much as 1000 PPm was detected. The strong lithologic control of these uranium mineralizations together with the lack of evidences of hydrothermal activity implies an intrinsic source for the uranium. The uranium, most likely, was transported and introduced into the sediments, by geochemically active groundwater, during their deposition. Uranium, from this solution, could have been adsorbed onto organic matter or clay minerals

  14. Lower Carboniferous Siderites: A Product of Bottom Seeps and Bacterial Metanogenesis (Subpolar Urals)

    Science.gov (United States)

    Antoshkina, A. I.; Ryabinkina, N. N.

    2018-02-01

    Complex modern micro- and spectroscopic methods for study of siderite concretions in the Lower Carboniferous terrigenous strata on the Kozhym River (Subpolar Urals) have shown that its formation was caused by destruction of clay minerals due to the activity of bacterial communities. The abundance of these bacteria was caused by gas-fluid seeps and bacterial methanogenesis processes in bottom deposits. In basins with normal marine fauna, this led to local desalination, hydrogen sulfide contamination, mass collapse of primary organisms, and the development of element-specific bacteria. The occurrence of these bacteria caused the formation of specific authigenic mineralization in the concretion of sideritic bacteriolites: the framboidal pyrite, sphalerite, galenite, barite, sulfoselenides, and tellurides.

  15. EFFECTS OF SOIL TREATMENT BY COAL MINING CARBONIFEROUS WASTE SLUDGE IN MAIZE GROWING

    Directory of Open Access Journals (Sweden)

    Robin Mujačić

    2011-11-01

    Full Text Available The multifuncional role and importance of organic matter in soil is widely known. It is also known that the organic matter in soil is subjected to microbiological-biochemical processes of transformation, which includes synthesis of humus as well as it’s decomposition -mineralization. Mineralization means transformation-decomposition of organic matter by microbiological processes to mineral products; plant nutrients and water + CO2 as starting and ending component of photosyntesis. Nutrients are partly plant available with fertilizing effect, partly lost from the soil - leaching in ground water, causing it’s eutrophication, but CO2 in atmosphere participates in greenhouse effect. Practically, mineralization means decreasing of organic matter content in soil and soil degradation [1,4]. In natural ecosystems (phytocenoses natural forests and meadows, it is almost a balanced between inflow and consumption of organic matter, while the cultural and anthropogenic soils agrobiocenosis in general, this relationship is disturbed that there is a disproportion between the inflow and loss [1,4]. Therefore, various materials that contains organic material (waste, various flotation, sludge, etc. are often used with more or less success. One of such materials, as well as the potential fertilizer, is carboniferous lake sludge like waste of coal mining sedimented at the bottom of the lake in huge quantities, which is the subject of our reasearch. The research were conducted to determine its fertilizing efects and value for repairing of physical and chemical properties of soil. The research refered to: -- Laboratory analysis of physical and chemical characteristics of the carboniferous sludge samples, -- Analysis of soil of the experimental field -- Research on heavy metals concentration in soil of the experimental farm and in carboniferous sludge, and Research of fertilizing effects of sludge, comparative mineral fertilizer and farmyard manure treatment by

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

    Directory of Open Access Journals (Sweden)

    Conghui Xiong

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

  17. Understanding the mobilisation of metal pollution associated with historical mining in a carboniferous upland catchment.

    Science.gov (United States)

    Valencia-Avellan, Magaly; Slack, Rebecca; Stockdale, Anthony; Mortimer, Robert John George

    2017-08-16

    Point and diffuse pollution from metal mining has led to severe environmental damage worldwide. Mine drainage is a significant problem for riverine ecosystems, it is commonly acidic (AMD), but neutral mine drainage (NMD) can also occur. A representative environment for studying metal pollution from NMD is provided by carboniferous catchments characterised by a circumneutral pH and high concentrations of carbonates, supporting the formation of secondary metal-minerals as potential sinks of metals. The present study focuses on understanding the mobility of metal pollution associated with historical mining in a carboniferous upland catchment. In the uplands of the UK, river water, sediments and spoil wastes were collected over a period of fourteen months, samples were chemically analysed to identify the main metal sources and their relationships with geological and hydrological factors. Correlation tests and principal component analysis suggest that the underlying limestone bedrock controls pH and weathering reactions. Significant metal concentrations from mining activities were measured for zinc (4.3 mg l -1 ), and lead (0.3 mg l -1 ), attributed to processes such as oxidation of mined ores (e.g. sphalerite, galena) or dissolution of precipitated secondary metal-minerals (e.g. cerussite, smithsonite). Zinc and lead mobility indicated strong dependence on biogeochemistry and hydrological conditions (e.g. pH and flow) at specific locations in the catchment. Annual loads of zinc and lead (2.9 and 0.2 tonnes per year) demonstrate a significant source of both metals to downstream river reaches. Metal pollution results in a large area of catchment having a depleted chemical status with likely effects on the aquatic ecology. This study provides an improved understanding of geological and hydrological processes controlling water chemistry, which is critical to assessing metal sources and mobilization, especially in neutral mine drainage areas.

  18. Upper Carboniferous retroarc volcanism with submarine and subaerial facies at the western Gondwana margin of Argentina

    Science.gov (United States)

    Koukharsky, M.; Kleiman, L.; Etcheverría, M.; Quenardelle, S.; Bercowski, F.

    2009-04-01

    During Late Carboniferous times a continental magmatic arc developed at the western margin of Gondwana in South America, as several marine sedimentary basins were formed at the same time in the retroarc region. North of 33°S, at Cordón Agua del Jagüel, Precordillera of Mendoza, Argentina, a volcanic sequence crops out which was emplaced in a submarine environment with some subaerial exposures, and it is intercalated in marine sediments of Agua del Jagüel Formation, which fills of one of these retroarc basins. This paper presents, for the first time, a facies analyses together with geochemical and isotopic data of this volcanic suite, suggesting its deposition in an ensialic retroarc marine basin. The volcanic succession comprises debris flows with either sedimentary or volcanic fragments, base surge, resedimented massive and laminated dacitic-andesitic hyaloclastite, pillow lava, basic hyaloclastite and dacitic-andesitic lavas and hyaloclastite facies. Its composition is bimodal, either basaltic or dacitic-andesitic. The geochemistry data indicate a subalkaline, low K calk-alkaline and metaluminous affinity. The geochemistry of the basalts points to an origin of the magmas from a depleted mantle source with some crustal contamination. Conversely, the geochemistry of the dacites-andesites shows an important participation of both crustal components and subduction related fluids. A different magmatic source for the basalts than for the dacites-andesites is also supported by Sr and Nd isotopic initial ratios and Nd model ages. The characteristics of this magmatic suite suggest its emplacement in an extensional setting probably associated with the presence of a steepened subduction zone at this latitude during Upper Carboniferous times.

  19. Glaciation in the surroundings of Prášilské Lake (Bohemian Forest, Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Mentlík, P.; Minár, J.; Břízová, E.; Lisá, Lenka; Tábořík, P.; Stacke, V.

    2010-01-01

    Roč. 117, 1/2 (2010), s. 181-194 ISSN 0169-555X Institutional research plan: CEZ:AV0Z30130516 Keywords : Bohemian Forest * Pleistocene glaciations * Prášilské Lake * Šumava * sedimentology * chronology Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.352, year: 2010

  20. A Million-Year Record of Glaciation in the Tropical Andes

    Science.gov (United States)

    Smith, J. A.; Seltzer, G. O.; Rodbell, D. T.; Farber, D. L.; Finkel, R. C.

    2004-12-01

    We present a longterm record of glaciation in the tropical Andes based on cosmogenic dating (10Be) of boulders on moraines. Well-preserved moraines in deglaciated valleys bordering the Junin Plain in central Peru ( ˜11° S, 76° W, 4000 m) were deposited during several glacial cycles extending back more than one million years before present (1 Myr BP). The presence of boulders with zero-erosion 10Be exposure ages >1 Myr constrains boulder erosion rates to relatively low values. For boulders at high altitudes, however, even low boulder erosion rates (0.3 to 0.5 m/Myr) make calculated old exposure ages markedly older [e.g., ˜20% older for a zero-erosion age of 400,000 10Be years (400 10Be kyr)]. Exposure ages recalculated with boulder erosion rates of 0.3 m/Myr straddle interglacial marine isotope stage (MIS) 11 ( ˜430-390 kyr BP), fall within glacial MIS 12 ( ˜480-430 kyr BP), but skip over glacial MIS 16 ( ˜670-630 kyr BP), perhaps the largest ice volume of the past 2 Myr. Increasing the erosion rate used in the calculations to 0.5 m/Myr moves ages into both MIS 11 and MIS 16. If we assume that the older Andean glaciations were indeed synchronous with global ice volume, our data suggest that boulder preservation cannot be treated as a simple linear process. Conversely, the data may be suggesting correctly that glaciation of the tropical Andes was not synchronous with the global glaciations as inferred from the marine isotope record. Our chronology for the last glacial maximum (LGM) in the region supports the idea of asynchrony between the global ice volume record and the terrestrial record of glaciation in the tropical Andes. The LGM in the Junin region of Peru and in the Cordillera Real of Bolivia (16° S 68° W) occurred ˜34 to 22 10Be kyr BP and was less extensive than older glaciations. Asynchrony between the LGM in the Northern Hemisphere ( ˜21 kyr BP) and the tropical Andes suggests that previous glaciations in the tropical Andes may have been

  1. Inferred Early Permian Arc Rifting in Bogda Mountain, Southernmost of the Central Asia Orogenic Belt: Evidence from a Peperite Bearing Volcano-Sedimentary Succession

    Science.gov (United States)

    Memtimin, M.; Guo, Z.

    2017-12-01

    Late Paleozoic tectonic history, especially Carboniferous-Permian periods, of the Central Asia Orogenic Belt (CAOB) is considered to be the turning point for the termination of terrane amalgamation and closure of the Paleoasian Ocean. However, the debate about the paleoenvironment and tectonic setting of the region during the period is still not resolved. In this study, we report a set of volcano-sedimentary sequence in the Bogda Mountain of the southernmost of CAOB, which is associated with contemporaneous subaqueous emplacement of and interaction between mafic lava and carbonate sediments. The succession contains four distinct facies including closely packed pillow basalts, pillow basalts with interstitial materials, hyaloclastites and peperites. We discuss their formation and emplacement mechanism, interaction between hot magma-water/unconsolidated sediments and thermal metamorphism during the interaction. Textural features of the sequence, especially hyaloclastites and peperites, provide clear evidence for in situ autofragmentation of lava flows, synvolcanic sedimentation of carbonates, fuel coolant interaction when hot magma bulldozed into wet unconsolidated sediments, and represent autochthonous origin of the succession. Lateral transition of the lithofacies indicate a progressively deepening subaqueous environment, resembling a stepwise evolution from early stage of volcanic intrusion with lower lava flux in shallower water level to increasingly subsiding basin with more lava flux in greater depth. Previous studies determined that the mafic magma was intruded around the Carboniferous-Permian boundary ( 300Ma), and geochemical studies showed the magma was originated from dry depleted mantle with little crustal contamination. Nevertheless, the succession was thought to be fault related allochthones formation which was transferred in as part of a Carboniferous intraplate arc. Combining our findings with the previous study results, we propose a new model to

  2. Application of the method of optimum increase of Carboniferous gass exploitation for the determination of its extractable amount from the space of attenuated plant of the Paskov Mine

    Directory of Open Access Journals (Sweden)

    Dragon Vladimír

    2003-09-01

    Full Text Available A way of optimum extraction increase of Carboniferous gas which can be applied in any mine of the Ostrava-Karviná Mining District (OKMD during the current period of the restructuralisation and mining attenuation.

  3. The geological model calibration - Learnings from integration of reservoir geology and field performance - Example from the upper carboniferous reservoirs of the Southern North Sea

    NARCIS (Netherlands)

    Moscariello, A.; Hoof, T.B. van; Kunakbayeva, G.; Veen, J.H. ten; Belt, F. van den; Twerda, A.; Peters, L.; Davis, P.; Williams, H.

    2013-01-01

    The Geological Model Calibration - Learnings from Integration of Reservoir Geology and Field Performance: example from the Upper Carboniferous Reservoirs of the Southern North Sea. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.

  4. Petrographic and EMP study of metamorphic rocks from the Variscan basement of Dinarides (Vranica Mountains, Bosnia and Herzegovina)

    Energy Technology Data Exchange (ETDEWEB)

    Hrvanovic, S [Department of Mineralogy and Petrology, Faculty of Natural Sciences, Comenius University, 84215 Bratislava (Slovakia)

    2012-04-25

    The Vranica Mountains are located in the middle part of Bosnia and Herzegovina or in the southeastern part of the Mid - Bosnian schist Mountains (MBSM). The Mid - Bosnian schist Mountains represent one of the largest allochtonous Paleozoic terranes in the Dinarides. This region is characterized by a multistage geodynamic evolution. The presented results concern Variscan metamorphism of the Silur-Devonian protolith formations that occurred mainly during the Early Carboniferous in LT/MP greenschist facies. Petrographical description of metamorphic rocks is completed by EMPA of muscovite, chlorite and chloritoid. The Early Alpine metamorphic overprint is related to the closure of a Tethyan Basin and Early Cretaceous collision of the Adria microplate with the Tissia-Moesia continental Blocks. The Neo-Alpine metamorphic overprint occurred due to the collision of the African and Euroasian Plates. (authors)

  5. Late Frasnian-Famennian climates based on palynomorph analyses and the question of the Late Devonian glaciations

    Science.gov (United States)

    Streel, Maurice; Caputo, Mário V.; Loboziak, Stanislas; Melo, José Henrique G.

    2000-11-01

    have alternated with less cold but wetter climates, thus giving rise to the development of mountain glaciers in high latitudes and explaining the jerking character of the global major marine regression. In high latitude regions, the development of an ice cap reaching sea level is only recorded by the end of the Latest Famennian, immediately below the DCB but, even if glacial evidences are not known at near the FFB, a short (0.1 Ma?) glaciation seems the best reasonable explanation of the major eustatic fall following the Kellwasser Event. The sudden growth and decay of a hypothetical Earliest Famennian ice sheet can be explained by the reduction and, later, increase in greenhouse capacity of the atmosphere. These changes in the atmospheric CO 2 might have provoked changes in the mode of ocean-atmosphere operation. It may also be partly controlled by a volcanic paroxysm and/or bolide impacts. The Hony microtektites represent the best known evidence of the impact of extraterrestrial bodies on Earth corresponding to the UKW, and they are immediately followed by a regression, suggested by the quantitative analysis of acritarch assemblages. In the paleo-tropical Late Famennian, a peat-forming vascular plant community occurs for the first time and makes possible quantitative palynology of autochthonous sediments allowing the recognition of different swamp and near-swamp characteristic miospores. The early Latest Famennian starts with a widespread transgression which could correspond to the melting phases of the hypothetical Late Famennian mountain glaciers. During the end-Famennian, the coastal lowland vegetation has a worldwide distribution from sub-polar to equatorial regions. The climate has become less cold in high latitudes but wetter than before probably because the midlatitude cyclonic activity allows sufficient polar transportation of moisture to form large snow cover. Extensive coastal glaciers developed in different Bolivian and Brazilian basins, well dated by

  6. Contemporary suspended sediment yield of a partly glaciated catchment, Riffler Bach (Tyrol, Austria)

    Science.gov (United States)

    Weber, Martin; Baewert, Henning; Morche, David

    2015-04-01

    Due to glacier retreat since the LIA (Little Ice Age) proglacial areas in high mountain landscapes are growing. These systems are characterized by a high geomorphological activity, especially in the fluvial subsystem. Despite the long tradition of geomorphological research in the European Alps there is a still a lack of understanding in the interactions between hydrology, sediment sources, sediments sinks and suspended sediment transport. As emphasized by ORWIN ET AL. (2010) those problems can be solved by gathering data in a higher frequency and/or in a higher spatial resolution or density - both leading to a big amount of data. In 2012 a gauging station was installed at the outlet of the partly glaciated catchment of the Riffler Bach (Kaunertal valley, Tyrol). During the ablation seasons in 2012 and 2013 water stage was logged automatically every 15 minutes. In both seasons discharge was measured at different water levels to calculate a stage-discharge relation. Additionally, water samples were taken by an automatic water sampler. Within 16 sampling cycles with sampling frequencies ranging from 1 to 24 hours 389 water samples have been collected. The samples were filtered to calculate the suspended sediment concentration (SSC) of each sample. Furthermore, the climate station Weißsee provided meteorological data at a 15 minute interval. Due to the high variability in suspended sediment transport in proglacial rivers it is impossible to compute a robust annual Q-SSC-relation. Hence, two other approaches were used to calculate the suspended sediment load (SSL) and the suspended sediment yield (SSY): A) Q-SSC-relations for every single sampling cycle (e.g. GEILHAUSEN ET AL. 2013) B) Q-SSC-relations based on classification of dominant runoff-generating processes (e.g. ORWIN AND SMART 2004). The first approach uses commonly operated analysis methods that are well understood. While the hydro-climatic approach is more feasible to explain discharge generation and to

  7. Criteria for identification of carbonate reservoirs according to well logging data (carboniferous deposits of Astrakhan' vault taken as an example)

    International Nuclear Information System (INIS)

    Makarova, A.N.; Mitalev, I.A.

    1979-01-01

    Described are the criteria for identification of carbonate reservoirs according to well logging data (carboniferous deposits of Astrakhan' vault taken as an example). According to gamma logging and cavitymetry data clay areas (decreased readings of neutron-gamma logging opposite dense rocks) are distinguished in a well log. ''Reservoir-nonreserVoir'' boundary is relatively drawn on the basis of the relation between neutron-gamma logaing indications and average general porosity of carbonate rocks determined by accoustic and neutron gamma logging

  8. Trace Fossils as Indicators of Depositional Sequence Boundaries in Lower Carboniferous Deep-Sea Fan Environment Moravice Formation, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Lehotský, T.; Bábek, O.; Mikuláš, Radek; Zapletal, J.

    2002-01-01

    Roč. 14, - (2002), s. 59-60 ISSN 1210-9606. [Áelazno 2002. Meeting of the Czech Tectonic Studies Group /7./. Áelazno, 09.05.2002-12.05.2002] R&D Projects: GA ČR GA205/00/0118 Keywords : trace fossils * Carboniferous * Deep- Sea Environment Subject RIV: DB - Geology ; Mineralogy http://geolines.gli.cas.cz/fileadmin/volumes/volume14/G14-059.pdf

  9. Carboniferous continental arc in the Hegenshan accretionary belt: Constrains from plutonic complex in central Inner Mongolia

    Science.gov (United States)

    Wei, Ruihua; Gao, Yongfeng; Xu, Shengchuan; Santosh, M.; Xin, Houtian; Zhang, Zhenmin; Li, Weilong; Liu, Yafang

    2018-05-01

    The architecture and tectonic evolution of the Hegenshan accretionary belt in the Central Asian Orogenic Belt (CAOB) remains debated. Here we present an integrated study of zircon U-Pb isotopic ages, whole rock major-trace elements, and Sr-Nd-Pb isotopic data from the Hegenshan volcanic-plutonic belt in central Inner Mongolia. Field observations and zircon U-Pb ages allow us to divide the intrusive complex into an early phase at 329-306 Ma and a late phase at 304 to 299 Ma. The intrusive bodies belong to two magma series: calc-alkaline rocks with I-type affinity and A-type granites. The early intrusions are composed of granodiorite, monzogranite and porphyritic granite, and the late calc-alkaline intrusions include gabbro though diorite to granodiorite. The calc-alkaline intrusive rocks exhibit a well-defined compositional trend from gabbro to granite, reflecting continuous fractional crystallization. These rocks show obvious enrichment in LILEs and LREEs and relative depletion of HFSEs, typical of subduction-related magma. They also exhibit isotopic characteristics of mantle-derived magmas such as low initial 87Sr/86Sr (0.7029-0.7053), positive ɛNd(t) values (0.06-4.76) and low radiogenic Pb isotopic compositions ((206Pb/204Pb)I = 17.907-19.198, (207Pb/204Pb)I = 15.474-15.555, (208Pb/204Pb)I = 37.408-38.893). The marked consistency in geochemical and isotopic compositions between the intrusive rocks and the coeval Baoligaomiao volcanic rocks define a Carboniferous continental arc. Together with available regional data, we infer that this east-west trending continental arc was generated by northward subduction of the Hegenshan ocean during Carboniferous. The late alkali-feldspar granites and the high-Si rhyolites of the Baoligaomiao volcanic succession show similar geochemical compositions with high SiO2 and variable total alkali contents, and low TiO2, MgO and CaO. These rocks are characterized by unusually low Sr and Ba, and high abundances of Zr, Th, Nb, HREEs

  10. Greisen deposits associated to carboniferous post-orogenic granites with mineralization potential, Sierra de Fiambala, Catamarca, Argentina

    International Nuclear Information System (INIS)

    Fogliata, A. S.; Rubinstein, N. R.; Avila, J. C.; Baez, M.

    2008-01-01

    The Fiambala range is located in the central south part of the province of Catamarca, Western Sierras Pampeanas, Argentina. It is largely conformed by Precambrian metamorphic rocks, a Cambrian granitic intrusive, Ordovician basic and ultra basic rocks and epi zonal Carboniferous granites (Los Ratones, El Salto and Ayacucho Granites). The Carboniferous granites are sub alkaline, weakly peraluminous, high silica (except for the porphyritic facies of Los Ratones granite) and moderately enriched in K. Contents of trace elements and REE indicate that El S alto and Ayacucho granites and the granular facies of Los Ratones granite have characteristics of evolved and differentiated granite associated with hydrothermal systems. The variations of trace elements, particularly Sn, W, U, Rb, Ba, Zr and Sr suggest that they correspond to granites with mineralization potential. Genetically linked to these granites there are Sn, W, U and minor base metals greisen deposits. The hydrothermal process that yield to these deposits involved two main alteration stages, beginning with alkali metasomatism follow by greissenization. According to the isotopic ages the hydrothermal processes postdate about 1 Ma the magmatic activity. The analyses of the granites and the associated greisen deposits confirm that the post orogenic carboniferous magmatism is the major metallogenetic control of the ore deposits from the studied area. This metallogenetic control could be a useful tool in prospecting similar deposits in the rest of the Western Sierras Pampeanas. (Author)

  11. Reconnaissance surficial geologic map of the Taylor Mountains quadrangle, southwestern Alaska

    Science.gov (United States)

    Wilson, Frederic H.

    2015-09-28

    This map and accompanying digital files are the result of the interpretation of aerial photographs from the 1950s as well as more modern imagery. The area, long considered a part of Alaska that was largely not glaciated (see Karlstrom, 1964; Coulter and others, 1965; or Péwé, 1975), actually has a long history reflecting local and more distant glaciations. An unpublished photogeologic map of the Taylor Mountains quadrangle from the 1950s by J.N. Platt Jr. was useful in the construction of this map. Limited new field mapping in the area was conducted as part of a mapping project in the Dillingham quadrangle to the south (Wilson and others, 2003); however, extensive aerial photograph interpretation represents the bulk of the mapping effort. The accompanying digital files show the sources for each line and geologic unit shown on the map.

  12. Mid Carboniferous lamprophyres, Cobequid Fault Zone, eastern Canada, linked to sodic granites, voluminous gabbro, and albitization

    Science.gov (United States)

    Pe-Piper, Georgia; Piper, David J. W.; Papoutsa, Angeliki

    2018-01-01

    Major intra-continental shear zones developed during the later stages of continental collision in a back-arc setting are sites of prolonged magmatism. Mantle metasomatism results from both melting of subducted sediments and oceanic crust. In the Cobequid Fault Zone of the northern Appalachians, back-arc A-type granites and gabbros dated ca. 360 Ma are locally intruded by lamprophyric dykes dated ca. 335 Ma. All the lamprophyres are kersantites with biotite and albite, lesser ilmenite, titanite and fluorapatite, and minor magmatic calcite, allanite, pyrite, magnetite, quartz and K-feldspar in some samples. The lamprophyres show enrichment in Rb, Ba, K, Th and REE and classify as calc-alkaline lamprophyre on the basis of biotite and whole rock chemistry. Pb isotopes lie on a mixing line between normal mantle-derived gabbro and OIB magma. Nd isotopes range from 1.3-3.5 εNdt, a little lower than in local gabbro. Most lamprophyres have δ18O = 3.8-4.4‰. Country rock is cut by pyrite-(Mg)-chlorite veins with euhedral allanite crystals that resemble the lamprophyres mineralogically, with the Mg-chlorite representing chloritized glass. Early Carboniferous unenriched mafic dykes and minor volcanic rocks are widespread along the major active strike-slip fault zones. The lamprophyres are geographically restricted to within 10 km of a small granitoid pluton with some sodic amphibole and widespread albitization. This was displaced by early Carboniferous strike-slip faulting from its original position close to the large Wentworth Pluton, the site of mantle-derived sodic amphibole granite, a major late gabbro pluton, and a volcanic carapace several kilometres thick, previously demonstrated to be the site of mantle upwelling and metasomatism. The age of the lamprophyres implies that enriched source material in upper lithospheric mantle or lower crust was displaced 50 km by crustal scale strike-slip faulting after enrichment by the mantle upwelling before lamprophyre emplacement

  13. Rocky Mountain Spotted Fever

    Science.gov (United States)

    ... with facebook share with twitter share with linkedin Rocky Mountain Spotted Fever Credit: CDC A male cayenne tick, Amblyomma cajennense, ... and New Mexico. Why Is the Study of Rocky Mountain Spotted Fever a Priority for NIAID? Tickborne diseases are becoming ...

  14. Rocky Mountain spotted fever

    Science.gov (United States)

    ... spotted fever on the foot Rocky Mountain spotted fever, petechial rash Antibodies Deer and dog tick References McElligott SC, Kihiczak GG, Schwartz RA. Rocky Mountain spotted fever and other rickettsial infections. In: Lebwohl MG, Heymann ...

  15. Relief Evolution in Tectonically Active Mountain Ranges

    Science.gov (United States)

    Whipple, Kelin X.

    2004-01-01

    The overall aims of this 3-yr project, as originally proposed were to: (1) investigate quantitatively the roles of fluvial and glacial erosion in the evolution of relief in mountainous regions, and (2) test rigorously the quality and accuracy of SRTM topographic data in areas of rugged relief - both the most challenging and of greatest interest to geomorphic, neotectonic, and hazards applications. Natural laboratories in both the western US and the Southern Alps of New Zealand were identified as most promising. The project has been both successful and productive, despite the fact that no SRTM data for our primary field sites in New Zealand were released on the time frame of the work effort. Given the delayed release of SRTM data, we pursued the scientific questions of the roles of fluvial and, especially, glacial erosion in the evolution of relief in mountainous regions using available digital elevation models (DEMs) for the Southern Alps of New Zealand (available at both 25m and 50m pixel sizes), and USGS 10m and 30m DEMs within the Western US. As emphasized in the original proposal, we chose the emphasis on the role of glacial modification of topographic relief because there has been little quantitative investigation of glacial erosion processes at landscape scale. This is particularly surprising considering the dramatic sculpting of most mid- and high-latitude mountain ranges, the prodigious quantities of glacially-derived sediment in terrestrial and marine basins, and the current cross-disciplinary interest in the role of denudational processes in orogenesis and the evolution of topography in general. Moreover, the evolution of glaciated landscapes is not only a fundamental problem in geomorphology in its own right, but also is at the heart of the debate over Late Cenozoic linkages between climate and tectonics.

  16. Determining the rates and drivers of headwall erosion within glaciated catchments in the NW Himalaya

    Science.gov (United States)

    Orr, E.; Owen, L. A.; Saha, S.; Caffee, M. W.

    2017-12-01

    Rates of headwall erosion are defined for fourteen glaciated catchments in the NW Himalaya by measuring 10Be terrestrial cosmogenic nuclide concentrations in supraglacial debris. The investigated catchments are located throughout three broad climatic zones, which include the Lesser Himalaya (rainfall >1000 mm a-1), Greater Himalaya (500-1000 mm a-1) and Transhimalaya (arid catchments that are occupied by sub-polar glaciers, suggesting that there are additional controls upon periglacial domain landscape change. Other factors and catchment-specific dynamics influencing these landscapes include, temperature, surface processes, topography, valley morphology, geologic setting and glacial history. Defining rates of headwall erosion is one of the first steps to understanding the nature of sediment production and transfer within high-altitude glaciated catchments, and highlights the importance of periglacial rockfall processes in landscape evolution.

  17. GLANAM (Glaciated North Atlantic Margins): A Marie Curie Initial Training Network between Norway, the UK & Denmark

    Science.gov (United States)

    Petter Sejrup, Hans; Oline Hjelstuen, Berit

    2015-04-01

    GLANAM (Glaciated North Atlantic Margins) is an Initial Training Network (ITN) funded under the EU Marie Curie Programme. It comprises 10 research partners from Norway, UK and Denmark, including 7 University research teams, 1 industrial full partner and 2 industrial associate partners. The GLANAM network will employ and train 15 early career researchers (Fellows). The aim of GLANAM is to improve the career prospects and development of young researchers in both the public and private sector within the field of earth science, focusing on North Atlantic glaciated margins. The young scientists will perform multi-disciplinary research and receive training in geophysics, remote sensing, GIS, sedimentology, geomorphology, stratigraphy, geochemistry and numerical modeling through three interconnected work packages that collectively address knowledge gaps related to the large, glacial age, sedimentary depocentres on the North Atlantic margin. The 15 Fellows will work on projects that geographically extend from Ireland in the south to the High Arctic. Filling these gaps will not only result in major new insights regarding glacial age processes on continental margins in general, but will also provide paleoclimate information essential for understanding the role of marine-based ice sheets in the climate system and for the testing of climate models. GLANAM brings together leading European research groups working on glaciated margins in a coordinated and collaborative research and training project. Focusing on the North Atlantic margins, this coordinated approach will lead to a major advance in the understanding of glaciated margins more widely and will fundamentally strengthen European research and build capacity in this field.

  18. An overview of the Upper Carboniferous fossil deposit at Linton, Ohio

    Energy Technology Data Exchange (ETDEWEB)

    Hook, R.W.; Baird, D.

    1988-03-01

    The cannel coal that underlies the Upper Freeport coal (Westphalian D, Upper Carboniferous) at Linton in Jefferson County, Ohio, has yielded a remarkable fossil assemblage of at least 10 invertebrate taxa and nearly 40 vertebrate taxa. Spirorbid worms, crustaceans (primarily syncarids and conchostracans), and fishes (coelacanths, haplolepid palaeoniscoids, and xenacanth sharks) are the most abundant fossils in the deposit; small aquatic amphibians (including nectridean, temnospondyl, and aistopod species) are also common. Other arthropod and tetrapod taxa are exceedingly rare and possess obvious adaptations for terrestial existence. The fossiliferous cannel originated as the sapropelic filling of an approximately 15-m-deep abandoned river meander within an alluviated delta plain setting. Remains of animals that lived in and near the freshwater oxbow accumulated in this anaerobic, scavenger-free lake bottom. The assemblage is autochthonous at the scale of the floodplain lake and its margins and represents a lowland biocoenose. Previous paleoecological interpretations of the Linton assemblage and similar Westphalian vertebrate deposits cannot be upheld because they are based largely on paleontological inferences and incorrect paleoenvironmental diagnoses. 34 refs., 3 figs., 3 tabs.

  19. Reservoir heterogeneity in carboniferous sandstone of the Black Warrior basin. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

    1994-06-01

    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  20. Global iridium anomaly, mass extinction, and redox change at the Devonian-Carboniferous boundary

    Energy Technology Data Exchange (ETDEWEB)

    Wang, K. (Geological Survey of Canada, Calgary, Alberta (Canada) Univ. of Calgary, Alberta (Canada)); Attrep, M. Jr.; Orth, C.J. (Los Alamos National Lab., NM (United States))

    1993-12-01

    Iridium abundance anomalies have been found on a global scale in the Devonian-Carboniferous (D-C) boundary interval, which records one of the largest Phanerozoic mass-extinction events, an event that devastated many groups of living organisms, such as plants, ammonoids, trilobites, conodonts, fish, foraminiferans, brachiopods, and ostracodes. At or very close to the D-C boundary, there exists a geographically widespread black-shale interval, and Ir abundances reach anomalous maxima of 0.148 ppb (Montagne Noire, France), 0.138 ppb (Alberta, Canada) 0.140 ppb (Carnic Alps, Austria), 0.156 ppb (Guangxi, China), 0.258 ppb (Guizhou, China), and 0.250 ppb (Oklahoma). The discovery of global D-C Ir anomalies argues for an impact-extinction model. However, nonchondritic ratios of Ir to other important elements and a lack of physical evidence (shocked quartz, microtektites) do not support such a scenario. The fact that all Ir abundance maxima are at sharp redox boundaries in these sections leads us to conclude that the Ir anomalies likely resulted from a sudden change in paleo-redox conditions during deposition and/or early diagenesis. 36 refs., 2 figs., 1 tab.

  1. Reservoir heterogeneity in Carboniferous sandstone of the Black Warrior basin. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

    1994-04-01

    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  2. Is the extent of glaciation limited by marine gas-hydrates?

    Science.gov (United States)

    Paull, Charles K.; Ussler, William; Dillon, William P.

    1991-01-01

    Methane may have been released to the atmosphere during the Quaternary from Arctic shelf gas-hydrates as a result of thermal decomposition caused by climatic warming and rising sea-level; this release of methane (a greenhouse gas) may represent a positive feedback on global warming [Revelle, 1983; Kvenvolden, 1988a; Nisbet, 1990]. We consider the response to sea-level changes by the immense amount of gas-hydrate that exists in continental rise sediments, and suggest that the reverse situation may apply—that release of methane trapped in the deep-sea sediments as gas-hydrates may provide a negative feedback to advancing glaciation. Methane is likely to be released from deep-sea gas-hydrates as sea-level falls because methane gas-hydrates decompose with pressure decrease. Methane would be released to sediment pore space at shallow sub-bottom depths (100's of meters beneath the seafloor, commonly at water depths of 500 to 4,000 m) producing zones of markedly decreased sediment strength, leading to slumping [Carpenter, 1981; Kayen, 1988] and abrupt release of the gas. Methane is likely to be released to the atmosphere in spikes that become larger and more frequent as glaciation progresses. Because addition of methane to the atmosphere warms the planet, this process provides a negative feedback to glaciation, and could trigger deglaciation.

  3. Assessment of geomorphological and hydrological changes produced by Pleistocene glaciations in a Patagonian basin

    Science.gov (United States)

    Scordo, Facundo; Seitz, Carina; Melo, Walter D.; Piccolo, M. Cintia; Perillo, Gerardo M. E.

    2018-04-01

    This work aims to assess how Pleistocene glaciations modeled the landscape in the upper Senguer River basin and its relationship to current watershed features (drainage surface and fluvial hydrological regime). During the Pleistocene six glacial lobes developed in the upper basin of the Senguer River localized east of the Andean range in southern Argentinean Patagonia between 43° 36' - 46° 27‧ S. To describe the topography and hydrology, map the geomorphology, and propose an evolution of the study area during the Pleistocene we employed multitemporal Landsat images, national geological sheets and a mosaic of the digital elevation model (Shuttle Radar Topography Mission) along with fieldwork. The main conclusion is that until the Middle Pleistocene, the drainage divide of the Senguer River basin was located to the west of its current limits and its rivers drained the meltwater of the glaciers during interglacial periods. However, processes of drainage inversion and drainage surface reduction occurred in the headwater of most rivers of the basin during the Late Pleistocene. Those processes were favored by a relative shorter glacial extension during LGM and the dam effect produced by the moraines of the Post GPG I and III glaciations. Thus, since the Late Pleistocene, the headwaters of several rivers in the basin have been reduced, and the moraines corresponding to the Middle Pleistocene glaciations currently divide the watersheds that drain towards the Senguer River from those that flow west towards the Pacific Ocean.

  4. Constraining Middle Pleistocene Glaciations in Birmingham, England; Using Optical Stimulated Luminescence (OSL) Dating.

    Science.gov (United States)

    Gibson, S. M.; Gibbard, P. L.; Bateman, M. D.; Boreham, S.

    2014-12-01

    Birmingham is built on a complex sequence of Middle Pleistocene sediments, representing at least three lowland glaciations (MIS12, MIS6, and MIS2). British Geological Survey mapping accounts 75% of the land mass as Quaternary deposits; predominantly glacial-sandy tills, glacial-fluvial sands, clays and organic silts and peats. Understanding the age of fluvial-glacial outwash, related to specific glaciations, is critical in establishing a Geochronology of Birmingham. Shotton (1953) found a series of Middle Pleistocene glacial sediments, termed the Wolstonian, intermediate in age between MIS11 and MIS5e Interglacial's. Uncertainty surrounding the relation to East Anglian sequences developed by Rose (1987) implies Birmingham sequences should be referred to MIS12. Despite this, younger Middle Pleistocene glacial sequences occur in Birmingham, yet uncertainty has deepened over our understanding of the complex, inaccessible sediments, especially as deposits have similar extent with MIS2 sequences. Five Optical Stimulated Luminescence (OSL) dates from three sites around Birmingham have been sampled. East of Birmingham, ice advanced from the Irish Sea and later the North East. In Wolston, a sample of outwash sand, associated with the Thurssington Till, is dated. In Meriden, two samples of outwash sands, associated with a distal Oadby Till, are dated. West of Birmingham, ice advanced from the Welsh Ice Sheet. In Seisdon, two samples of an Esker and outwash sand, associated with a Ridgeacre Till, are dated. Correlation of OSL dates provide an important constraint on understanding the history of Birmingham. Using GSI3D modeling to correlate geochronology and sedimentology, the significance of OSL dating can be understood within the complex sequences (and regional stratigraphy), complimented by Cosmogenic and Palynology dates taken in South West and North East. OSL dating on Birmingham's outwash sands, deposited by extensive repeated Middle Pleistocene glaciations, asserts the

  5. Extreme mass flux from the glaciated, collisional St. Elias Orogen: Preliminary results from IODP Expedition 341 (Invited)

    Science.gov (United States)

    Gulick, S. P.; Jaeger, J. M.

    2013-12-01

    Integrated Ocean Drilling Program Expedition 341 drilled a cross-margin transect to investigate the linkages between global climate change, modification of the dynamics of surficial processes, and subsequent tectonic responses. The Gulf of Alaska (GoA) borders the St. Elias orogen, the highest coastal mountain range on Earth. Exp. 341 drilled five sites within a regional seismic reflection grid that spans from the distal Surveyor Fan to the continental shelf. More than 3000 m of high-quality core coupled with seismic reflection profiles collected with nested vertical resolution allows us to address the major objectives of drilling in the GoA. These objectives were to: 1) document the tectonic response of an active orogenic system to late Miocene to recent climate change; 2) establish the timing of advance/retreat phases of the northern Cordilleran ice sheet to test its relation to dynamics of other global ice sheets; 3) implement an expanded source-to-sink study of the interactions between glacial, tectonic, and oceanographic processes responsible for creation of one of the thickest Neogene high-latitude continental margin sequences; 4) understand the dynamics of productivity, nutrients, freshwater input to the ocean, and ocean circulation in the northeast Pacific and their role in the global carbon cycle, and 5) document the spatial and temporal behavior of the geomagnetic field at extremely high temporal resolution in an under-sampled region of the globe. The Exp. 341 cross-margin transect discovered transitions in sediment accumulation rates from >100 m/Ma at the distal site to > 1000 m/Ma in the proximal fan, slope and on the continental shelf that provide a telescoping view of strata formation from the Miocene to the Holocene. Complete recovery and development of spliced sedimentary records of the Pleistocene through Holocene were achieved at the distal, proximal, and slope Sites U1417, U1418, and U1419, respectively, because of exceptional piston core

  6. Carboniferous geology and uranium potential of the northeast flank of the Parana Basin and southwest flank of the Parnaiba Basin, Brazil

    International Nuclear Information System (INIS)

    Andrade, S.M. de; Camarco, P.E.N.

    1984-01-01

    The Carboniferous sequences of the northeast flank of the Parana Basin and those of the southwest flank of the Parnaiba Basin have been the subject of discussion and polemics for quite a long time, especially in terms of their stratigraphic relations and depositional environments. Thus, we reinforce our main objective, which is to furnish data for the definition of the uranium potential in these Carboniferous sediments, by adding recently acquired information that should aid in the clarification of the existing controversies. The Carboniferous along the northeast flank of the Parana Basin is represented by the Aquidauana Formation which has been informally divided into three members: lower, middle and upper members. The middle member, of marine origin, constitutes a prospective target for uranium and phosphate associations, in which sandstones interbedded with shales constitute the host rocks. On the other hand, the Carboniferous of the southwest margin of the Parnaiba Basin, which encompasses the Longa, Poti and Piaui Formations has shown very remote possibilities of uranium occurrences. The regional structural framework, as reflected by the Carboniferous rocks along both basin flanks, is characterized by homoclines cut by gravity faults. The faults along these weakness zones were occasionally intruded by basic rocks of Cretaceous age. Superimposed on the regional structure, open folds appear in the form of anticlines and domes. These folds are discontinuous structures resulting from uplift due to vertical stresses or result from differential subsidence along the limbs of the folds. (Author) [pt

  7. History and development of Carboniferous palynology in North America during the early and middle twentieth century

    Energy Technology Data Exchange (ETDEWEB)

    Cross, A.T.; Kosanke, R.M. [Michigan State University, East Lansing, MI (United States). Dept. of Geological Sciences

    1995-12-31

    Three main roots of upper Palaeozoic palynology in North America date from the opening of the twentieth century. These are Gresley`s recognition of spores in Iowa coal balls in 1901, analyses of spores by Sellards from Mazon Creek compressions in 1902, and Thiessen`s analyses of dispersed spores from coal maceration and thin sections in 1913. The Pollen Analysis Circular brought workers into contact in the 1940s and generated interest in older fossils. The Paleobotanical Section of the Botanical Society of America (1936) and the Coal Geology Division of the Geological Society of America (1955) encouraged palynologists to participate in meetings and field trips. Fundamental papers by Schopf et al. in 1944 and Kosanke in 1950 established Carboniferous palynology in North America. Active teaching and research centers at the University of Chicago in the 1920s and the University of Illinois and Coe College in the 1930s spawned new palynological centers, particularly throughout the Midwest. Palynological contributions on dispersed spores, mainly from coals and associated rocks, appeared from educational centers from 1929 through the 1950s. Limited reviews of early researches at early palynologic centers are here included by region. Palynology applied to petroleum exploration appeared in the 1940s and major petroleum companies had palynology laboratories in place by 1960. The first international palynology journals appeared in the 1950s and catalogs first appeared in the mid-1960s, except the Catalog of Fossil Spores and Pollen, which began in 1957. The first specific palynology organization, the American Association of Stratigraphic Palynologisst, was founded in 1968. 304 refs., 38 figs

  8. Sustainable management of transboundary water resources (Belgium/France): Characterization and modelling of the Carboniferous aquifer

    Science.gov (United States)

    Bastien, J.; Picot-Colbeaux, G.; Crastes de Paulet, F.; Rorive, A.; Bouvet, A.; Goderniaux, P.; Thiery, D.

    2016-12-01

    The Carboniferous Limestone groundwater extends from East to West across Belgium and the North of France (1420 km²). In a high population density and industrial activity region, it represents huge volumes of abstracted groundwater (98 Mm³). The aquifer thus constitutes a critical reserve for public distribution and industrial uses. This water reservoir is intensively exploited from both sides of the border since the end of the 19th century. Historically, this transboundary aquifer was overexploited, due to the massive requirements of the industry. As a consequence, a substantial piezometric level decrease was observed (up to 50 m). Due to the karstic nature of the aquifer, many sinkhole collapses were induced in the studied area. A reduction of the abstracted volumes was implemented in the 90s, which contributed to the relative stabilization of the piezometric levels, but the equilibrium remains uncertain. Due to complex political, urbanistic and industrial developments across this region, a reasonable and long-term management model was needed, involving all concerned countries and regions. Within the framework of the Interreg ScaldWIN Project, a belgo-french collaboration allowed the acquisition of new sets of geological and hydrogeological data. A new piezometric map was established and correlated with chemical and isotopic analyses. It enabled a more accurate knowledge on the main flow directions within the aquifer, and the relation between recharge area and the confined area, where groundwater is aged up to 10000 years. A new numerical model of the aquifer was implemented and calibrated by using the MARTHE code. This 4 layer-model includes a part of the French chalk aquifer and integrates all abstracted groundwater volumes (wells and quarries) from 1900 to 2010. Atmospheric and surface waters and potential evapotranspiration are included in relation to the groundwater. This model is used by the different partners to consider globally and locally the impact of

  9. Tonganoxichnus, a new insect trace from the Upper Carboniferous of eastern Kansas

    Science.gov (United States)

    Mangano, M.G.; Buatois, L.A.; Maples, C.G.; Lanier, Wendy E.

    1997-01-01

    Upper Carboniferous tidal rhythmites of the Tonganoxie Sandstone Member (Stranger Formation) at Buildex Quarry, eastern Kansas, USA, host a relatively diverse arthropod-dominated ichnofauna. Bilaterally symmetrical traces displaying unique anterior and posterior sets of morphological features are well represented within the assemblage. A new ichnogenus, Tonganoxichnus, is proposed for these traces. T. buildexensis, the type ichnospecies, has an anterior region characterized by the presence of a frontal pair of maxillary palp impressions, followed by a head impression and three pairs of conspicuous thoracic appendage imprints symmetrically opposite along a median axis. The posterior region commonly exhibits numerous delicate chevron-like markings, recording the abdominal appendages, and a thin, straight, terminal extension. T. buildexensis is interpreted as a resting trace. A second ichnospecies, T. ottawensis, is characterized by a fan-like arrangement of mostly bifid scratch marks at the anterior area that records the head- and thoracic-appendage backstrokes against the substrate. The posterior area shows chevron-like markings or small subcircular impressions that record the abdominal appendages of the animal, also ending in a thin, straight, terminal extension. Specimens display lateral repetition, and are commonly grouped into twos or threes with a fix point at the posteriormost tail-like structure. T. ottawensis is interpreted as a jumping structure, probably in connection with feeding purposes. The two ichnospecies occur in close association, and share sufficient morphologic features to support the same type of arthropod producer. T. buildexensis closely mimics the ventral anatomy of the tracemaker, whereas T. ottawensis records the jumping abilities of the animal providing significant ethologic and paleoecologic information. The presence of well-differentiated cephalic, thoracic, and abdominal features, particularly in T. buildexensis, resembles the

  10. Tabulate Corals after the Frasnian/Famennian Crisis: A Unique Fauna from the Holy Cross Mountains, Poland.

    Science.gov (United States)

    Zapalski, Mikołaj K; Berkowski, Błażej; Wrzołek, Tomasz

    2016-01-01

    Famennian tabulate corals were very rare worldwide, and their biodiversity was relatively low. Here we report a unique tabulate fauna from the mid- and late Famennian of the western part of the Holy Cross Mountains (Kowala and Ostrówka), Poland. We describe eight species (four of them new, namely ?Michelinia vinni sp. nov., Thamnoptychia mistiaeni sp. nov., Syringopora kowalensis sp. nov. and Syringopora hilarowiczi sp. nov.); the whole fauna consists of ten species (two others described in previous papers). These corals form two assemblages-the lower, mid-Famennian with Thamnoptychia and the upper, late Famennian with representatives of genera ?Michelinia, Favosites, Syringopora and ?Yavorskia. The Famennian tabulates from Kowala represent the richest Famennian assemblage appearing after the F/F crisis (these faunas appear some 10 Ma after the extinction event). Corals described here most probably inhabited deeper water settings, near the limit between euphotic and disphotic zones or slightly above. At generic level, these faunas show similarities to other Devonian and Carboniferous faunas, which might suggest their ancestry to at least several Carboniferous lineages. Tabulate faunas described here represent new recruits (the basin of the Holy Cross mountains was not a refuge during the F/F crisis) and have no direct evolutionary linkage to Frasnian faunas from Kowala. The colonization of the seafloor took place in two separate steps: first was monospecific assemblage of Thamnoptychia, and later came the diversified Favosites-Syringopora-Michelinia fauna.

  11. Tabulate Corals after the Frasnian/Famennian Crisis: A Unique Fauna from the Holy Cross Mountains, Poland.

    Directory of Open Access Journals (Sweden)

    Mikołaj K Zapalski

    Full Text Available Famennian tabulate corals were very rare worldwide, and their biodiversity was relatively low. Here we report a unique tabulate fauna from the mid- and late Famennian of the western part of the Holy Cross Mountains (Kowala and Ostrówka, Poland. We describe eight species (four of them new, namely ?Michelinia vinni sp. nov., Thamnoptychia mistiaeni sp. nov., Syringopora kowalensis sp. nov. and Syringopora hilarowiczi sp. nov.; the whole fauna consists of ten species (two others described in previous papers. These corals form two assemblages-the lower, mid-Famennian with Thamnoptychia and the upper, late Famennian with representatives of genera ?Michelinia, Favosites, Syringopora and ?Yavorskia. The Famennian tabulates from Kowala represent the richest Famennian assemblage appearing after the F/F crisis (these faunas appear some 10 Ma after the extinction event. Corals described here most probably inhabited deeper water settings, near the limit between euphotic and disphotic zones or slightly above. At generic level, these faunas show similarities to other Devonian and Carboniferous faunas, which might suggest their ancestry to at least several Carboniferous lineages. Tabulate faunas described here represent new recruits (the basin of the Holy Cross mountains was not a refuge during the F/F crisis and have no direct evolutionary linkage to Frasnian faunas from Kowala. The colonization of the seafloor took place in two separate steps: first was monospecific assemblage of Thamnoptychia, and later came the diversified Favosites-Syringopora-Michelinia fauna.

  12. 87Sr/86Sr ratios in permo-carboniferous sea water from the analyses of well-preserved brachiopod shells

    International Nuclear Information System (INIS)

    Popp, B.N.; Anderson, T.F.

    1986-01-01

    Sr isotopic analyses of well-preserved portions of Permo-Carboniferous brachiopods distributed globally confirm the general shape of the Sr isotope age curve established by previous workers for this time interval. There is little variation between the SR isotopic composition of unaltered portions of brachiopods and that of portions of the same shell interpreted to be diagenetically altered (based on cathodoluminescence, elemental, and stable isotopic data). However, the Sr isotopic composition in diagenetically altered micritic matrix adjacent to the shell is more radiogenic. The Sr isotopic composition in the unaltered portions of calcitic megafossils has potential as a stratigraphic tool. (author)

  13. A new, rare and distinctive species of Panorthoptera (Insecta, Archaeorthoptera from the Upper Carboniferous of Xiaheyan (Ningxia, China

    Directory of Open Access Journals (Sweden)

    J.-J. Gu

    2017-11-01

    Full Text Available The Xiaheyan locality is providing abundant material on one of the earliest insect faunas. The most common species are comparatively remote relatives of Orthoptera (grasshoppers, crickets and katydids, belonging to the Archaeorthoptera nec Panorthoptera (the latter including crown Orthoptera. We establish the genus Sinogerarus gen. nov. to accommodate a new, rare species, S. pectinatus spec. nov., which can be conclusively assigned to Panorthoptera. It therefore represents the second occurrence of the group at this locality. The new species displays a distinctive combination of character states, adding to the knowledge of a number of Upper Carboniferous Panorthoptera whose relationships are poorly understood.

  14. Mountain Plover [ds109

    Data.gov (United States)

    California Natural Resource Agency — Point locations representing observations of mountain plover (Charadrius montanus) feeding and roosting flocks (and occasional individuals) documented during an...

  15. Petrological, geochemical, isotopic, and geochronological constraints for the Late Devonian-Early Carboniferous magmatism in SW Gondwana (27-32°LS): an example of geodynamic switching

    Science.gov (United States)

    Dahlquist, Juan A.; Alasino, Pablo H.; Basei, Miguel A. S.; Morales Cámera, Matías M.; Macchioli Grande, Marcos; da Costa Campos Neto, Mario

    2018-04-01

    We report a study integrating 13 new U-Pb LA-MC-ICP-MS zircon ages and Hf-isotope data from dated magmatic zircons together with complete petrological and whole-rock geochemistry data for the dated granitic rocks. Sample selection was strongly based on knowledge reported in previous investigations. Latest Devonian-Early Carboniferous granite samples were collected along a transect of 900 km, from the inner continental region (present-day Eastern Sierras Pampeanas) to the magmatic arc (now Western Sierras Pampeanas and Frontal Cordillera). Based on these data together with ca. 100 published whole-rock geochemical analyses we conclude that Late Devonian-Early Carboniferous magmatism at this latitude represents continuous activity (ranging from 322 to 379 Ma) on the pre-Andean margin of SW Gondwana, although important whole-rock and isotopic compositional variations occurred through time and space. Combined whole-rock chemistry and isotope data reveal that peraluminous A-type magmatism started in the intracontinental region during the Late Devonian, with subsequent development of synchronous Carboniferous peraluminous and metaluminous A-type magmatism in the retro-arc region and calc-alkaline magmatism in the western paleomargin. We envisage that magmatic evolution was mainly controlled by episodic fluctuations in the angle of subduction of the oceanic plate (between flat-slab and normal subduction), supporting a geodynamic switching model. Subduction fluctuations were relatively fast (ca. 7 Ma) during the Late Devonian and Early Carboniferous, and the complete magmatic switch-off and switch-on process lasted for 57 Ma. Hf T DM values of zircon (igneous and inherited) from some Carboniferous peraluminous A-type granites in the retro-arc suggest that Gondwana continental lithosphere formed during previous orogenies was partly the source of the Devonian-Carboniferous granitic magmas, thus precluding the generation of the parental magmas from exotic terranes.

  16. Geoprospective study of a nuclear waste repository. Climatology: climatic changes and glaciations

    International Nuclear Information System (INIS)

    Courbouleix, S.

    1985-01-01

    Within the frame of a contract with the CEC dealing with storage and disposal of radioactive wastes in geological formations, the B.R.G.M. has been involved in a research on climatic changes and glaciations. For over three million years, the terrestrial environment has undergone a climate crisis, which causes are still discussed. 700 000 years ago, the paroxysm of this crisis was caracterized by the development of big ice-caps in the northern hemisphere. The last important glacial expansion - the Wurm- begun 70 000 years ago and ended less than 10 000 years ago. Since then, the climate warmed up slightly again with the ''small glacial age'' between the 16th and the 19th centuries. All glaciers regressed during a warmer phase lasting about one century, but, since 1945, the trend is again to a deep in temperature, the climatologists are not able to agree on its causes and its possible develoment. Considering the amplitude and the frequency of the Quaternary climatic changes, it is difficult to think that the glacial crisis is over. Many arguments let suppose the contrary. Therefore, all evidences lead, to the probability of at least one new glaciation wither the next 100 000 years. The problem is to know its importance and when it will occur. If during the present interglacial time, all ices could melt, one can expect a rise sea-levels of about 80 m. On the contrary, in the case of a future glaciation of the same amplitude as the previous one, the stocking of waters by the ice-caps would bring down the sea-level to 120 m which would lead to an important erosion period and a drastic change in landscapes

  17. Analysis of the strength of sea gas pipelines of positive buoyancy conditioned by glaciation

    Science.gov (United States)

    Malkov, Venyamin; Kurbatova, Galina; Ermolaeva, Nadezhda; Malkova, Yulia; Petrukhin, Ruslan

    2018-05-01

    A technique for estimating the stress state of a gas pipeline laid along the seabed in northern latitudes in the presence of glaciation is proposed. It is assumed that the pipeline lies on the bottom of the seabed, but under certain conditions on the some part of the pipeline a glaciation is formed and the gas pipeline section in the place of glaciation can come off the ground due to the positive buoyancy of the ice. Calculation of additional stresses caused by bending of the pipeline is of practical interest for strength evaluation. The gas pipeline is a two-layer cylindrical shell of circular cross section. The inner layer is made of high-strength steel, the outer layer is made of reinforced ferroconcrete. The proposed methodology for calculating the gas pipeline for strength is based on the equations of the theory of shells. The procedure takes into account the effect of internal gas pressure, external pressure of sea water, the weight of two-layer gas pipeline and the weight of the ice layer. The lifting force created by the displaced fluid and the positive buoyancy of the ice is also taken into account. It is significant that the listed loads cause only two types of deformation of the gas pipeline: axisymmetric and antisymmetric. The interaction of the pipeline with the ground as an elastic foundation is not considered. The main objective of the research is to establish the fact of separation of part of the pipeline from the ground. The method of calculations of stresses and deformations occurring in a model sea gas pipeline is presented.

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

    Science.gov (United States)

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

    2016-02-10

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

  19. Late Variscan, Permo-Carboniferous, Al-K plutonism in the South Portuguese Zone: El Crispinejo cordierite-bearing granite

    Energy Technology Data Exchange (ETDEWEB)

    Díez Montes, A.; Valverde-Vaquero, P.; Rey-Moral, C.; Sánchez García, L.

    2017-07-01

    The El Crispinejo granite forms part of a small, but distinctive late intrusive suite of cordierite-bearing peraluminous granites in the South Portuguese Zone (SPZ). This granite has the best outcrop relationships of the suite. It cross-cuts different members of the Sierra Norte Batholith of the SPZ and the Carboniferous Volcano-Sedimentary Complex of the Iberian Pyrite Belt, producing contact metamorphism. This late pluton has a high K content which results in a contrasting geophysical response (K-Th-U) with respect to the surrounding trondhjemitic granitoids of the TTG suite of the Sierra Norte Batholith. A concordant monazite-zircon U-Pb ID-TIMS age of 300.5 +0.5/-1.5Ma demonstrates Permo-Carboniferous age for this late Variscan magmatic event. The granite is associated with a series of ore showings (F-Pb-Zn and Sn-W) which are completely different from the nearby, massive sulphide and manganese ore deposits of the Iberian Pyrite Belt, indicating the unique character of this intrusion.

  20. Irradiation of quartz grains - a new method of sedimentological analysis applied to Permian - Carboniferous arenites in the Maranhao Basin - Brazil

    International Nuclear Information System (INIS)

    Carmo Faria Junior, L.E. do

    1980-01-01

    The quartz grains of sediments and sedimentary rocks change their colour in variable intensity to smoky-quartz by X-ray irradiation, Co 60 or in reactors, dependent on their temperature of cristallization. The quantity of quartz grains which were stained and which were not stained after being irradiated are related to rock types from the source areas. This method was applied for selected sandstones of different stratigraphical levels of the Permian-Carboniferous in the Maranhao Basin of Brazil. Studeis on heavy minerals of these sandstones have been done before. The heavy mineral associations of the Permian Pedra de Fogo Formation corroborate the results of the analysis of quartz grains which indicate a predominance of the metamorphic rocks in the source area. However, the heavy mineral parageneses of the Carboniferous Piaui Formation are different. This may be because the frequency of those heavy minerals depend directly on the stage of the weathering of the sandstones. It should be mentioned that heavy minerals occur in paleozoic sediments only in a small quantity, sometimes below 1% of the rock constitution. The irradiation analysis, which is applied for the predominant mineral in sandstones, appears to be most reliable. It is used here as the basis for the interpretations presented. (Author) [pt

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-01

    Upper Carboniferous tight gas sandstone reservoirs in NW-Germany consist of thick successions of cyclothems. Our focus is the Westphalian D of the Piesberg quarry near Osnabrueck, which exposes cemented, faulted and jointed third-order coarse- to fine-grained sandstone cycles separated by anthracite coal seams. We characterize the rocks and the lateral variation of rock properties such as porosity to better constrain input data for reservoir modelling. Three cycles are exposed, each approximately 50 m thick. Rock types can be clearly distinguished by spectral gamma ray in the quarry. Sandstones are intensely compacted and cemented with quartz and generally characterized by low porosities < 8 % (Hepycnometry on plugs and cuttings). Porosities are secondary and mainly related to detrital carbonate dissolution. Around faults dissolution is higher and the porosities can increase to up to 25%. The normal faults show different throws in the quarry and bands of shale and coal have smeared into the fault at juxtaposed beds, which may result in compartments. They dominantly strike W-E and NNW-SSE, but subordinate NE-SW striking fault patterns are also present. Joints were analyzed in a 50 x 50 m section of the quarry wall using Lidar (Light detection and ranging) laser scanning, which allows the characterization of the lithology and quantitative measurement of bedding and fracture orientation data in inaccessible areas. NNE-SSW and W-E joint sets are accompanied by northeasterly and northwesterly striking sets. Around faults, fault planes and fractures are cemented with quartz veins, showing localized mass transport. Due to the intense cementation, the sandstones can reach uniaxial strengths of more than 100 MPa normal to bedding, and approximately 50 MPa parallel to bedding. Sandstone beds within and close to faults are leached by fluids, and their uniaxial strength is reduced by a factor of more than two. Our high resolution field data enables a better understanding of

  2. Flow variation in Astore river under assumed glaciated extents due to climate change

    International Nuclear Information System (INIS)

    Naeem, U.A.

    2012-01-01

    Various researchers have concluded the existence of many glaciers in doubt by the end of this century due to global warming phenomenon. The great Himalayas are also under such stress. The recent acceleration in rainfall pattern resulted the ever worst destruction due to floods (2010) in Pakistan. Many Watershed models, capable of incorporating the climate change scenarios have been developed in this regard to predict the future flows. But it is not easy to select the most appropriate model for a particular watershed to get the best results. In this regard. the paper is an effort where the analysis has been made on Astore Watershed, Pakistan, by considering the model results obtained from the three watershed models i.e. UBC Watershed Model, HBV-Met and HBV-PRECIS. The results are obtained by considering different glaciated extents of 100%, 50% and 0% under future climate scenario (SRES A2), simulated by PRECIS Regional Climate Model for (2071-2100). For changed climate scenario, discharges for the simulations at 100% reduction in glaciated area were -72%, -15% and-46% for HBV-Met, HBV-PRECIS and UBC Watershed Model respectively. (author)

  3. Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean.

    Science.gov (United States)

    Coxall, Helen K; Wilson, Paul A; Pälike, Heiko; Lear, Caroline H; Backman, Jan

    2005-01-06

    The ocean depth at which the rate of calcium carbonate input from surface waters equals the rate of dissolution is termed the calcite compensation depth. At present, this depth is approximately 4,500 m, with some variation between and within ocean basins. The calcite compensation depth is linked to ocean acidity, which is in turn linked to atmospheric carbon dioxide concentrations and hence global climate. Geological records of changes in the calcite compensation depth show a prominent deepening of more than 1 km near the Eocene/Oligocene boundary (approximately 34 million years ago) when significant permanent ice sheets first appeared on Antarctica, but the relationship between these two events is poorly understood. Here we present ocean sediment records of calcium carbonate content as well as carbon and oxygen isotopic compositions from the tropical Pacific Ocean that cover the Eocene/Oligocene boundary. We find that the deepening of the calcite compensation depth was more rapid than previously documented and occurred in two jumps of about 40,000 years each, synchronous with the stepwise onset of Antarctic ice-sheet growth. The glaciation was initiated, after climatic preconditioning, by an interval when the Earth's orbit of the Sun favoured cool summers. The changes in oxygen-isotope composition across the Eocene/Oligocene boundary are too large to be explained by Antarctic ice-sheet growth alone and must therefore also indicate contemporaneous global cooling and/or Northern Hemisphere glaciation.

  4. Simulation of the European ice sheet through the last glacial cycle and prediction of future glaciation

    International Nuclear Information System (INIS)

    Boulton, G.S.; Payne, A.

    1992-12-01

    Global climates of the recent past appear to correlate with patterns of variation in the earths orbit round the sun. As such orbital changes can be predicted into the future, it is argued that the pattern of natural long-term future change can also be estimated. From this, future trends of glaciation can be inferred. The physical and mathematical basis of a time-dependent, thermo mechanically coupled, three dimensional ice sheet model is described. The model is driven by changes in the equilibrium line altitude (ELA) on its surface. This causes flexure of the underlying lithosphere. The model is tuned to the maximum extension of the last (Weichselian) ice sheet and driven by an ELA fluctuation which reflects the NE Atlantic sea surface temperature fluctuation pattern during the last glacial cycle in such a way that the model reproduces the ice sheet margin at the glacial maximum. The distribution of internal ice sheet velocity, temperature, basal melting rate and sub glacial permafrost penetration are all computed. The model is then tested against its predictions of the areal pattern of ice sheet expansion and decay, the pattern of crustal flexure and relative sea level change, and the distribution of till produced by the last European ice sheet. The tested model is then driven by predictions of future climate change to produce simulations of future ice sheet glaciation in northern Europe

  5. Sensitivity study of rock mass response to glaciation at Finnsjoen, central Sweden

    International Nuclear Information System (INIS)

    Israelsson, J.; Rosengren, L.; Stephansson, O.

    1992-11-01

    The safety analysis SKB-91 of the Swedish Nuclear Fuel and Waste Management Company (SKB) paid specific attention to the glaciation scenario and related phenomena. In the first phase, Rosengren and Stephansson (1990), used the distinct element computer code UDEC to examine the response of the rock mass in the Finnsjoen area to the processes of glaciation and deglaciation. This report describes the second phase, in which the sensitivity of the results to different in situ stresses and fault zone strength properties have been analyzed. A statistical approach was used to extrapolate the range of in-situ stresses at depth from measured in-situ stresses at shallower depths. Three different linear in-situ stress variations with depth were defined using a 99% confidence interval. For each in-situ stress case, three fault zone strength assumptions were analyzed for an ice loading sequence, involving 3 km, 1 km, 0-1 km (ice wedge) and 0 km of ice thickness. Each combination of in-situ stress and fault zone strength was analyzed with and without an ice lake, situated on top of the ice sheet. Consequently, a total of 18 models were studied. The results indicated significant differences in stress distribution, failure (reactivation) of fault zones, and shear displacement on fault zones for some combinations of in-situ stress, fault zone strength, and ice lake pressure. Based on the results, several preliminary recommendations for repository siting are made, as well as recommendations for further study. (authors)

  6. Antarctic glaciation caused ocean circulation changes at the Eocene-Oligocene transition.

    Science.gov (United States)

    Goldner, A; Herold, N; Huber, M

    2014-07-31

    Two main hypotheses compete to explain global cooling and the abrupt growth of the Antarctic ice sheet across the Eocene-Oligocene transition about 34 million years ago: thermal isolation of Antarctica due to southern ocean gateway opening, and declining atmospheric CO2 (refs 5, 6). Increases in ocean thermal stratification and circulation in proxies across the Eocene-Oligocene transition have been interpreted as a unique signature of gateway opening, but at present both mechanisms remain possible. Here, using a coupled ocean-atmosphere model, we show that the rise of Antarctic glaciation, rather than altered palaeogeography, is best able to explain the observed oceanographic changes. We find that growth of the Antarctic ice sheet caused enhanced northward transport of Antarctic intermediate water and invigorated the formation of Antarctic bottom water, fundamentally reorganizing ocean circulation. Conversely, gateway openings had much less impact on ocean thermal stratification and circulation. Our results support available evidence that CO2 drawdown--not gateway opening--caused Antarctic ice sheet growth, and further show that these feedbacks in turn altered ocean circulation. The precise timing and rate of glaciation, and thus its impacts on ocean circulation, reflect the balance between potentially positive feedbacks (increases in sea ice extent and enhanced primary productivity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The Antarctic ice sheet had a complex, dynamic role in ocean circulation and heat fluxes during its initiation, and these processes are likely to operate in the future.

  7. Exploring the MIS M2 glaciation occurring during a warm and high atmospheric CO2 Pliocene background climate

    Science.gov (United States)

    Tan, Ning; Ramstein, Gilles; Dumas, Christophe; Contoux, Camille; Ladant, Jean-Baptiste; Sepulchre, Pierre; Zhang, Zhongshi; De Schepper, Stijn

    2017-08-01

    Prior to the Northern Hemisphere glaciation around ∼2.7 Ma, a large global glaciation corresponding to a 20 to 60 m sea-level drop occurred during Marine Isotope Stage (MIS) M2 (3.312-3.264 Ma), interrupted the period of global warmth and high CO2 concentration (350-450 ppmv) of the mid Piacenzian. Unlike the late Quaternary glaciations, the M2 glaciation only lasted 50 kyrs and occurred under uncertain CO2 concentration (220-390 ppmv). The mechanisms causing the onset and termination of the M2 glaciation remain enigmatic, but a recent geological hypothesis suggests that the re-opening and closing of the shallow Central American Seaway (CAS) might have played a key role. In this article, thanks to a series of climate simulations carried out using a fully coupled Atmosphere Ocean General Circulation Model (GCM) and a dynamic ice sheet model, we show that re-opening of the shallow CAS helps precondition the low-latitude oceanic circulation and affects the related northward energy transport, but cannot alone explain the onset of the M2 glaciation. The presence of a shallow open CAS, together with favourable orbital parameters, 220 ppmv of CO2 concentration, and the related vegetation and ice sheet feedback, led to a global ice sheet build-up producing a global sea-level drop in the lowest range of proxy-derived estimates. More importantly, our results show that the simulated closure of the CAS has a negligible impact on the NH ice sheet melt and cannot explain the MIS M2 termination.

  8. Advances in global mountain geomorphology

    Science.gov (United States)

    Slaymaker, Olav; Embleton-Hamann, Christine

    2018-05-01

    Three themes in global mountain geomorphology have been defined and reinforced over the past decade: (a) new ways of measuring, sensing, and analyzing mountain morphology; (b) a new emphasis on disconnectivity in mountain geomorphology; and (c) the emergence of concerns about the increasing influence of anthropogenic disturbance of the mountain geomorphic environment, especially in intertropical mountains where population densities are higher than in any other mountain region. Anthropogenically induced hydroclimate change increases geomorphic hazards and risks but also provides new opportunities for mountain landscape enhancement. Each theme is considered with respect to the distinctiveness of mountain geomorphology and in relation to important advances in research over the past decade. The traditional reliance on the high energy condition to define mountain geomorphology seems less important than the presence of unique mountain landforms and landscapes and the distinctive ways in which human activity and anthropogenically induced hydroclimate change are transforming mountain landscapes.

  9. Proceedings from glaciation and hydrogeology. Workshop on the impact of climate change and glaciations on rock stresses, groundwater flow and hydrochemistry - Past, present and future

    Energy Technology Data Exchange (ETDEWEB)

    King-Clayton, L.; Chapman, N. [eds.] [QuantiSci Ltd (United Kingdom); Ericsson, L.O. [ed.] [SKB, Stockholm (Sweden); Kautsky, F. [ed.] [SKI, Stockholm (Sweden)

    1997-04-01

    Assessment of the long term safety of radioactive waste disposal requires assimilation of evidence for the impact of climate change and especially glaciation on the geosphere, particularly in terms of its implications for: the distribution and stability of stress regimes, groundwater flux and flow patterns, groundwater chemistry, and thermal conditions. This workshop was intended to promote informal scientific discussion and the exchange of information and ideas between a wide range of disciplines such as climatology, glaciology, hydrology, hydrochemistry, rock mechanics and structural geology. Participants from outside the radioactive waste community were welcome. Of particular need were palaeosignatures, direct observational information and models of the impact of continental ice sheets and periglacial conditions on crystalline bedrock. The workshop has highlighted the fact that there is a great deal of interest in the area of climate change and its impact on the performance of a deep geological repository, but that there are still many issues remaining that require further resolution. The first half of these proceedings gives overviews of the discussions and conclusions from the different sessions at the workshop, as well as the general conclusion and summary. In the second half, summaries of 49 contributions to the workshop are printed. These summaries have been indexed separately.

  10. Proceedings from glaciation and hydrogeology. Workshop on the impact of climate change and glaciations on rock stresses, groundwater flow and hydrochemistry - Past, present and future

    International Nuclear Information System (INIS)

    King-Clayton, L.; Chapman, N.; Kautsky, F.

    1997-04-01

    Assessment of the long term safety of radioactive waste disposal requires assimilation of evidence for the impact of climate change and especially glaciation on the geosphere, particularly in terms of its implications for: the distribution and stability of stress regimes, groundwater flux and flow patterns, groundwater chemistry, and thermal conditions. This workshop was intended to promote informal scientific discussion and the exchange of information and ideas between a wide range of disciplines such as climatology, glaciology, hydrology, hydrochemistry, rock mechanics and structural geology. Participants from outside the radioactive waste community were welcome. Of particular need were palaeosignatures, direct observational information and models of the impact of continental ice sheets and periglacial conditions on crystalline bedrock. The workshop has highlighted the fact that there is a great deal of interest in the area of climate change and its impact on the performance of a deep geological repository, but that there are still many issues remaining that require further resolution. The first half of these proceedings gives overviews of the discussions and conclusions from the different sessions at the workshop, as well as the general conclusion and summary. In the second half, summaries of 49 contributions to the workshop are printed. These summaries have been indexed separately

  11. isotopic chronological study on gold-stibium deposits in Bayinbuluke area of Tianshan mountains

    International Nuclear Information System (INIS)

    Chen Fuwen; Li Huaqin

    2003-01-01

    Several gold-stibium deposits have recently been found in Bayinbuluke area of Tianshan Mountains, such as the Dashankou gold deposit and Chahansala stibium deposit. isotopic chronological study of mineralization show that the fluid inclusion Rb-Sr isochron age for gold-bearing pyrite-quartz veins and pyrite-limonite-quartz veins from the Dashankou gold mine are 354 ± 8.1 Ma (2 σ) and 344 ± 21 Ma (2 σ), respectively. The two ages are consistent in test errors, indicating the gold deposit was formed in early Carboniferous and related to regional shearing; the fluid inclusion Rb-Sr isochron age for quartz-stibnite veins and quartz-tetrahedrite-bismuthinite-stibnite veins from the Chahansala stibium mine is 257 ± 23 Ma (2 σ), indicating the deposit was formed during the late Hercynian-Early Indosinian Period and related to intracontinental deformation. (authors)

  12. Cuticles and spores of Senftenbergia plumosa (Artis) Bek and Pšenička from the Carboniferous of Pilsen Basin, Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Pšenička, J.; Bek, Jiří

    2003-01-01

    Roč. 125, 3-4 (2003), s. 299-312 ISSN 0034-6667 R&D Projects: GA AV ČR IAA3013902; GA MK RK01P03OMG023 Institutional research plan: CEZ:AV0Z3013912 Keywords : Carboniferous * cuticular analysis * ferns Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.935, year: 2003

  13. Trace fossils of the Moravice Formation from the southern Nízký Jeseník Mts. (Lower Carboniferous, Culm facies; Moravia, Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Mikuláš, Radek; Lehotský, T.; Bábek, O.

    2004-01-01

    Roč. 79, č. 2 (2004), s. 81-98 ISSN 1214-1119 R&D Projects: GA ČR(CZ) GA205/00/0118 Keywords : ichnofossils * Lower Carboniferous * Culm facies Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/bulletin/contents/2004/vol79no2/bullgeosci200402081.pdf

  14. Devonian/Carboniferous boundary glacioeustatic fluctuations in a platform-to-basin direction: A geochemical approach of sequence stratigraphy in pelagic settings

    Czech Academy of Sciences Publication Activity Database

    Bábek, O.; Kumpan, T.; Kalvoda, J.; Matys Grygar, Tomáš

    2016-01-01

    Roč. 337, MAY (2016), s. 81-99 ISSN 0037-0738 Institutional support: RVO:61388980 Keywords : Element geochemistry * Hangenberg event * Glacioeustasy * Devonian/Carboniferous boundary * Sedimentation rate Subject RIV: DD - Geochemistry Impact factor: 2.373, year: 2016

  15. Yucca Mountain digital database

    International Nuclear Information System (INIS)

    Daudt, C.R.; Hinze, W.J.

    1992-01-01

    This paper discusses the Yucca Mountain Digital Database (DDB) which is a digital, PC-based geographical database of geoscience-related characteristics of the proposed high-level waste (HLW) repository site of Yucca Mountain, Nevada. It was created to provide the US Nuclear Regulatory Commission's (NRC) Advisory Committee on Nuclear Waste (ACNW) and its staff with a visual perspective of geological, geophysical, and hydrological features at the Yucca Mountain site as discussed in the Department of Energy's (DOE) pre-licensing reports

  16. Deglacial history of the Pensacola Mountains, Antarctica from glacial geomorphology and cosmogenic nuclide surface exposure dating

    Science.gov (United States)

    Bentley, M. J.; Hein, A. S.; Sugden, D. E.; Whitehouse, P. L.; Shanks, R.; Xu, S.; Freeman, S. P. H. T.

    2017-02-01

    The retreat history of the Antarctic Ice Sheet is important for understanding rapid deglaciation, as well as to constrain numerical ice sheet models and ice loading models required for glacial isostatic adjustment modelling. There is particular debate about the extent of grounded ice in the Weddell Sea embayment at the Last Glacial Maximum, and its subsequent deglacial history. Here we provide a new dataset of geomorphological observations and cosmogenic nuclide surface exposure ages of erratic samples that constrain the deglacial history of the Pensacola Mountains, adjacent to the present day Foundation Ice Stream and Academy Glacier in the southern Weddell Sea embayment. We show there is evidence of at least two glaciations, the first of which was relatively old and warm-based, and a more recent cold-based glaciation. During the most recent glaciation ice thickened by at least 450 m in the Williams Hills and at least 380 m on Mt Bragg. Progressive thinning from these sites was well underway by 10 ka BP and ice reached present levels by 2.5 ka BP, and is broadly similar to the relatively modest thinning histories in the southern Ellsworth Mountains. The thinning history is consistent with, but does not mandate, a Late Holocene retreat of the grounding line to a smaller-than-present configuration, as has been recently hypothesized based on ice sheet and glacial isostatic modelling. The data also show that clasts with complex exposure histories are pervasive and that clast recycling is highly site-dependent. These new data provide constraints on a reconstruction of the retreat history of the formerly-expanded Foundation Ice Stream, derived using a numerical flowband model.

  17. Reconstructing the groundwater flow in the Baltic Basin during the Last glaciation

    Science.gov (United States)

    Saks, T.; Sennikovs, J.; Timuhins, A.; Kalvāns, A.

    2012-04-01

    In last decades it has been discussed that most large ice sheets tend to reside on warm beds even in harsh clima tic conditions and subglacial melting occurs due to geothermal heat flow and deformation heat of the ice flow. However the subglacial groundwater recharge and flow conditions have been addressed in only few studies. The aim of this study is to establish the groundwater flow pattern in the Baltic Basin below the Scandinavian ice sheet during the Late Weichselian glaciation. The calculation results are compared to the known distribution of the groundwater body of the glacial origin found in Cambrian - Vendian (Cm-V) aquifer in the Northern Estonia which is believed to have originated as a result of subglacial meltwater infiltration during the reoccurring glaciations. Steady state regional groundwater flow model of the Baltic Basin was used to simulate the groundwater flow beneath the ice sheet with its geometry adjusted to reflect the subglacial topography. Ice thickness modelling data (Argus&Peltier, 2010) was used for the setup of the boundary conditions: the meltwater pressure at the ice bed was assumed equal to the overlying ice mass. The modelling results suggest two main recharge areas of the Cm-V aquifer system, and reversed groundwater flow that persisted for at least 14 thousand years. Model results show that the groundwater flow velocities in the Cm-V aquifer in the recharge area in N-Estonia beneath the ice sheet exceeded the present velocities by a factor of 10 on average. The calculated meltwater volume recharged into the Cm-V aquifer system during the Late Weichselian corresponds roughly to the estimated, however, considering the fact, that the study area has been glaciated at least 4 times this is an overestimation. The modeling results attest the hypothesis of light dO18 groundwater glacial origin in the Cm-V aquifer system, however the volumes, timing and processes involved in the meltwater intrusion are yet to be explored. This study was

  18. A 565 Ma old glaciation in the Ediacaran of peri-Gondwanan West Africa

    Science.gov (United States)

    Linnemann, Ulf; Pidal, Agustín Pieren; Hofmann, Mandy; Drost, Kerstin; Quesada, Cecilio; Gerdes, Axel; Marko, Linda; Gärtner, Andreas; Zieger, Johannes; Ulrich, Jens; Krause, Rita; Vickers-Rich, Patricia; Horak, Jana

    2018-04-01

    In the Cadomian orogen of the NE Bohemian Massif and of SW Iberia, a post-Gaskiers glacial event dated at c. 565 Ma has been detected. Such Ediacaran-aged glaciomarine deposits occur in the Weesenstein and Clanzschwitz groups of the Saxo-Thuringian zone (Bohemia) and in the Lower Alcudian group of the southern Central Iberian zone (Iberia). Both areas are parts of Cadomia situated in the Western and Central European Variscides. Glaciomarine sedimentary rocks are characterized by such features as dropstones, flat iron-shaped pebbles (" Bügeleisen- Geschiebe"), facetted pebbles, dreikanters, and zircon grains affected by ice abrasion. For age and provenance determination, LA-ICP-MS U-Pb ages ( n = 1124) and Hf isotope ( n = 446) analyses were performed. The maximum age of the glaciomarine deposits within a Cadomian back-arc basin based on U-Pb analytics resulted in the youngest detrital zircon populations showing ages of 562-565 Ma and of c. 566-576 Ma old zircon derived from granitoid pebbles within the diamictites. The youngest age recorded was 538-540 Ma based on zircon from the plutons which had intruded the previously deformed Ediacaran metasedimentary rocks. Previously described glaciomarine diamictites of Cadomia (Weesenstein, Clanzschwitz, and Orellana diamictites) are most definitely younger than the c. 579-581 Ma Gaskiers glaciation in Newfoundland (Gaskiers) and in SE New England (Squantum). We propose the term Weesenstein- Orellana glaciation for this new Ediacaran glacial event, named after the most relevant regions of exposure. Palaeogeographically, these glaciomarine diamictites and related sedimentary deposits lie on the periphery of the West African Craton (western peri-Gondwana), and evidence has been provided by detrital zircon U-Pb ages and their Hf isotope composition. Correlation with similar glaciomarine deposits in the Anti-Atlas (Bou Azzer) and Saudi Arabia suggests a continued distribution of post-Gaskiers glacial deposits along the

  19. Association between catastrophic paleovegetation changes during Devonian-Carboniferous boundary and the formation of giant massive sulfide deposits

    Science.gov (United States)

    Menor-Salván, Cesar; Tornos, Fernando; Fernández-Remolar, David; Amils, Ricardo

    2010-11-01

    The Iberian Pyrite Belt (SW Iberia) is one of the largest sulfur anomalies in the Earth's crust. In the southern Iberian Pyrite Belt, more than 820 Mt of exhalative massive sulfides were deposited in less than one million years at the Devonian-Carboniferous boundary. The shale of the ore-bearing horizon contains biomarkers indicating major biogenic activity in a methanogenic setting, including a five-fold increase in typical vascular plant biomarkers and a significant anomaly in those probably indicating the presence of thermophilic Archaea. This contrasts with signatures in the average sedimentary rocks of the basin that indicate the sediments settled in oxic to sub-oxic environments, and that they have only minor biomarkers derived from continental paleoflora. These data show that the formation of the mineralization was not only related to major hydrothermal activity synchronous with volcanism but may also have been controlled by the input of large amounts of organic matter, mostly derived from the degradation of woodland detritus sourced in the nearby continent. This massive influx of organic matter could have accelerated extremophilic microbial activity that used short-chain hydrocarbons as electron donors for seawater sulfate reduction, resulting in concomitant massive sulfide precipitation. We propose that the giant massive sulfide deposits resulted from overlapping of geological and biological processes that occurred at the Devonian to Carboniferous transition, including: (1) continent collision during the onset of the Variscan orogeny leading to major paleogeographic changes and volcanism; (2) dramatic stress of continental ecosystems due to the combination of climatic change, volcanism, variations in the sea level and erosion on a regional scale; (3) major biomass destruction and increase of organic supply to marine environments; and, (4) generation of anoxic conditions and the thriving of sulfate reducing microorganisms. Under these conditions, massive

  20. Palynology and detrital zircon geochronology of the Carboniferous Fenestella Shale Formation of the Tethyan realm in Kashmir Himalaya: Implications for global correlation and floristic evolution

    Science.gov (United States)

    Agnihotri, Deepa; Pandita, Sundeep K.; Tewari, Rajni; Ram-Awatar; Linnemann, Ulf; Pillai, S. Suresh K.; Joshi, Arun; Gautam, Saurabh; Kumar, Kamlesh

    2018-05-01

    First palynological data, supplemented by detrital zircon U-Pb ages, from the Fenestella Shale Formation near the Gund Village in the Banihal area of Jammu and Kashmir State, India, provide new insights into the floristic evolution of Gondwana during the Late Palaeozoic, especially in India, from where the Carboniferous-Permian macro- and microfloral records are impoverished. We also present a first approach to the palynological correlation of the Carboniferous-Permian palynoassemblages described from the various Gondwana countries. The palynomorphs from the Fenestella Shale Formation are fairly well preserved and diversified and include 11 genera and 18 species. While the trilete spores and striate bisaccate pollen grains are scarce, monosaccate pollen taxa mainly - Parasaccites, Plicatipollenites and Potonieisporites are dominant. The assemblage is most similar to the Parasaccites korbaensis palynozone of the Lower Gondwana basins of the Indian peninsula and the Stage 2 palynozone of the late Carboniferous of east Australia. Besides, it is comparable with the known Carboniferous assemblages of Pakistan, Yemen and South America; Carboniferous-early Permian assemblages of South Africa and Permian assemblages of Antarctica. The sediment source of the siliciclastic shelf and delta deposits intercalated in the Fenestella Shale Formation is a hinterland in which Precambrian rocks dominantly were exposed and the Th-U ratios of detrital zircons suggest, that most rocks exposed on the erosion level in the hinterland had a felsic composition. The youngest U-Pb zircon age of the investigated fossiliferous strata is 329 ± 16 Ma (late Visean to early Serpukhovian), providing a maximum age of deposition of the studied succession. Based on the affinities of the palynofloral assemblage and earlier palaeontological records, a warm, temperate and arid climate has been inferred for the Fenestella Shale Formation.

  1. Education and Yucca Mountain

    International Nuclear Information System (INIS)

    Lamont, M.A.

    1995-01-01

    This paper outlines a middle school social studies curriculum taught in Nevada. The curriculum was designed to educate students about issues related to the Yucca Mountain project. The paper focuses on the activities used in the curriculum

  2. Recreational mountain biking injuries.

    Science.gov (United States)

    Aitken, S A; Biant, L C; Court-Brown, Charles M

    2011-04-01

    Mountain biking is increasing in popularity worldwide. The injury patterns associated with elite level and competitive mountain biking are known. This study analysed the incidence, spectrum and risk factors for injuries sustained during recreational mountain biking. The injury rate was 1.54 injuries per 1000 biker exposures. Men were more commonly injured than women, with those aged 30-39 years at highest risk. The commonest types of injury were wounding, skeletal fracture and musculoskeletal soft tissue injury. Joint dislocations occurred more commonly in older mountain bikers. The limbs were more commonly injured than the axial skeleton. The highest hospital admission rates were observed with head, neck and torso injuries. Protective body armour, clip-in pedals and the use of a full-suspension bicycle may confer a protective effect.

  3. Landforms of High Mountains

    Directory of Open Access Journals (Sweden)

    Derek A. McDougall

    2016-05-01

    Full Text Available Reviewed: Landforms of High Mountains. By Alexander Stahr and Ewald Langenscheidt. Heidelberg, Germany: Springer, 2015. viii + 158 pp. US$ 129.99. Also available as an e-book. ISBN 978-3-642-53714-1.

  4. Acute mountain sickness

    Science.gov (United States)

    ... GO About MedlinePlus Site Map FAQs Customer Support Health Topics Drugs & Supplements Videos & Tools Español You Are Here: Home → Medical Encyclopedia → Acute mountain sickness URL of this page: //medlineplus.gov/ency/article/ ...

  5. YUCCA MOUNTAIN SITE DESCRIPTION

    International Nuclear Information System (INIS)

    Simmons, A.M.

    2004-01-01

    The ''Yucca Mountain Site Description'' summarizes, in a single document, the current state of knowledge and understanding of the natural system at Yucca Mountain. It describes the geology; geochemistry; past, present, and projected future climate; regional hydrologic system; and flow and transport within the unsaturated and saturated zones at the site. In addition, it discusses factors affecting radionuclide transport, the effect of thermal loading on the natural system, and tectonic hazards. The ''Yucca Mountain Site Description'' is broad in nature. It summarizes investigations carried out as part of the Yucca Mountain Project since 1988, but it also includes work done at the site in earlier years, as well as studies performed by others. The document has been prepared under the Office of Civilian Radioactive Waste Management quality assurance program for the Yucca Mountain Project. Yucca Mountain is located in Nye County in southern Nevada. The site lies in the north-central part of the Basin and Range physiographic province, within the northernmost subprovince commonly referred to as the Great Basin. The basin and range physiography reflects the extensional tectonic regime that has affected the region during the middle and late Cenozoic Era. Yucca Mountain was initially selected for characterization, in part, because of its thick unsaturated zone, its arid to semiarid climate, and the existence of a rock type that would support excavation of stable openings. In 1987, the United States Congress directed that Yucca Mountain be the only site characterized to evaluate its suitability for development of a geologic repository for high-level radioactive waste and spent nuclear fuel

  6. YUCCA MOUNTAIN SITE DESCRIPTION

    Energy Technology Data Exchange (ETDEWEB)

    A.M. Simmons

    2004-04-16

    The ''Yucca Mountain Site Description'' summarizes, in a single document, the current state of knowledge and understanding of the natural system at Yucca Mountain. It describes the geology; geochemistry; past, present, and projected future climate; regional hydrologic system; and flow and transport within the unsaturated and saturated zones at the site. In addition, it discusses factors affecting radionuclide transport, the effect of thermal loading on the natural system, and tectonic hazards. The ''Yucca Mountain Site Description'' is broad in nature. It summarizes investigations carried out as part of the Yucca Mountain Project since 1988, but it also includes work done at the site in earlier years, as well as studies performed by others. The document has been prepared under the Office of Civilian Radioactive Waste Management quality assurance program for the Yucca Mountain Project. Yucca Mountain is located in Nye County in southern Nevada. The site lies in the north-central part of the Basin and Range physiographic province, within the northernmost subprovince commonly referred to as the Great Basin. The basin and range physiography reflects the extensional tectonic regime that has affected the region during the middle and late Cenozoic Era. Yucca Mountain was initially selected for characterization, in part, because of its thick unsaturated zone, its arid to semiarid climate, and the existence of a rock type that would support excavation of stable openings. In 1987, the United States Congress directed that Yucca Mountain be the only site characterized to evaluate its suitability for development of a geologic repository for high-level radioactive waste and spent nuclear fuel.

  7. Hypothesis for the last stage of glaciation in the Černé Lake area (Bohemian Forest, Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Vočadlová, K.; Křížek, M.; Čtvrtlíková, Martina; Hekera, P.

    2007-01-01

    Roč. 13, č. 3 (2007), s. 205-216 ISSN 1211-7420 R&D Projects: GA ČR GA206/04/0967; GA AV ČR(CZ) KJB300460501 Institutional research plan: CEZ:AV0Z60050516 Keywords : geomorphology * glaciation * Černé Lake Subject RIV: EF - Botanics

  8. Subglacial bed conditions during Late Pleistocene glaciations and their impact on ice dynamics in the southern North Sea

    NARCIS (Netherlands)

    Passchier, S.; Laban, C.; Mesdag, C.S.; Rijsdijk, K.F.

    2010-01-01

    Changes in subglacial bed conditions through multiple glaciations and their effect on ice dynamics are addressed through an analysis of glacigenic sequences in the Upper Pleistocene stratigraphy of the southern North Sea basin. During Elsterian (MIS 12) ice growth, till deposition was subdued when

  9. Greenhouse effect and ice ages: historical perspective; Effet de serre et glaciations, une perspective historique

    Energy Technology Data Exchange (ETDEWEB)

    Bard, E. [College de France, Chaire d' Evolution du Climat et de l' Ocean, 75 - Paris (France); CEREGE (UMR 6635), 13 - Aix en Provence (France)

    2004-06-01

    This article provides a brief historical perspective on the first scientific research on the greenhouse effect and glaciations. While these two aspects of our climate can be investigated separately, naturalists, physicists and chemists during the 19. century were interested jointly in both issues, as well as the possible relationship between them. The contributions of famous pioneers are mentioned, ranging from scholars with encyclopedic knowledge such as Horace-Benedict de Saussure, to modern scientists like Svante Arrhenius, who was first to predict global warming as a consequence of using fossil fuels. Despite fragmentary observations, these pioneers had prophetic insights. Indeed, the main fundamental concepts used nowadays have been developed during the 19. century. However, we must wait until the second half of the 20. century to see a true revolution of investigative techniques in the Earth Sciences, enabling full access to previously unknown components of the climate system, such as deep oceans and the interior of the polar ice caps. (author)

  10. Mechanical effects associated with surface loading of dry rock due to glaciation

    International Nuclear Information System (INIS)

    Wahi, K.K.; Hunter, R.L.

    1985-01-01

    Many scenarios of interest for a repository in the Pasco Basin begin with glaciation. Loading and unloading of joints and fractures due to the weight of ice sheets could affect the hydrologic properties of the host rock and surrounding units. Scoping calculations performed using two-dimensional numerical models with simplifying assumptions predict stress changes and uplift or subsidence caused by an advancing glacier. The magnitudes of surface uplift and subsidence predicted by the study agree well with previous independent predictions. Peak stress unloading near the repository horizon is a small fraction of the ambient stress. Any resultant aperture increase is likewise small. Based on the results of this study, mechanical loading caused by a glacier is expected to have a minimal effect on rock permeability, assuming that the excess compressive loads do not crush the rock. 13 refs., 3 figs., 1 tab

  11. An Exploration of Mechanisms for Mediating the Influence of Extratropical Glaciation on the Tropical Climate

    Science.gov (United States)

    Pierrehumbert, R. T.; Frierson, D. M.

    2006-05-01

    To obtain a better understanding of the basic mechanisms by which the atmosphere transmits extratropical influences into the tropics, we have analyzed a series of general circulation model experiments carried out with idealized continental boundary conditions. These experiments were carried out with the FOAM1.5 model, which is in essence a portable Beowulf-oriented reimplementation of CCM3. In accord with our focus on the atmosphere in this work, the atmospheric model is coupled to a mixed-layer ocean with lateral ocean heat flux set to zero. The continental geometry consists of a pair of zonally symmetric continents, one centered on each pole. The Southern Hemisphere continent extends to 65S, and is kept glaciated in all experiments. The Northern Hemisphere continent extends to 42N, and is glaciated in the NHCOLD experiment but bare land in the NHWARM experiment. Sea ice feedback was suppressed in these simulations, but given the geometry of the Northern Hemisphere continent, the NHCOLD case can be taken as representing the combined forcing due to land glaciation and equatorward advance of sea ice. These experiments allow us to examine, in a very clean way, the response of the tropics to a very large extratropical cooling imposed at the surface, in a model which is energetically closed. Comparison of the two simulations has yielded the following results. The principal means by which the midlatitude glaciation affects the tropics is via a marked increase in poleward NH wintertime sensible heat flux, which is uncompensated by reduction in latent heat flux. The coupling of the storm tracks to the tropics is weak, however, and causes only a moderate cooling in the Northern subtropics and hardly any south of the Equator. The dynamics behind this barrier effect are discussed. The increased sensible heat flux,however, causes a considerable strengthening of the Hadley circulation; this strengthening allows the ITCZ precipitation to remain approximately unchanged between

  12. Glaciation and Hydrologic Variability in Tropical South America During the Last 400,000 Years

    Science.gov (United States)

    Fritz, S. C.; Baker, P. A.; Seltzer, G. O.; Ekdahl, E. J.; Ballantyne, A.

    2005-12-01

    The expansion and contraction of northern continental ice sheets is a fundamental characteristic of the Quaternary. However, the extent of tropical glaciation is poorly constrained, particularly for periods prior to the Last Glacial Maximum (LGM). Similarly, the magnitude and timing of hydrologic variation in tropical South America is not clearly defined over multiple glacial cycles. Thus, the relative roles of global temperature change and insolation control of the South American Summer Monsoon (SASM) are unclear. We have reconstructed the timing of glaciation and precipitation variability in the tropical Andes of South America from drill cores from Lake Titicaca, Bolivia/Peru. The longest core (site LT01-2B, 235 m water depth) is 136 m and consists of four major silt-dominated units with high magnetic susceptibility, low organic carbon concentration, and no carbonate, which are indicative of extensive glacial activity in the cordillera surrounding the lake. These units alternate with laminated low-susceptibility units, with high carbonate and organic carbon concentrations, which reflect times when detrital input from the watershed was low and lake-level was lowered to below the outlet threshold, driving carbonate precipitation. Thus, the stratigraphy suggests that the core spans four major periods of glaciation and the subsequent interstadials. Core chronology is based on radiocarbon in the uppermost 25m, U-series dates on aragonite laminae, and tuning of the calcium carbonate stratigraphy in the lowermost sediments to the Vostok CO2 record. High-resolution (ca. 100 yr) sampling of sediments spanning the last glacial stage shows distinct millennial-scale variability from 20 - 65 kyr BP. This variability is evident in the periodic deposition of turbidites, which are characterized by low biogenic silica concentrations, elevated benthic diatom abundances, heavy carbon isotopic values, high C/N ratios, and an increase in mean grain size - a composite signal

  13. Meltwater channel scars and the extent of Mid-Pleistocene glaciation in central Pennsylvania

    Science.gov (United States)

    Marsh, Ben

    2017-10-01

    High-resolution digital topographic data permit morphological analyses of glacial processes in detail that was previously infeasible. High-level glaciofluvial erosional scars in central Pennsylvania, identified and delimited using LiDAR data, define the approximate ice depth during a pre-Wisconsin advance, > 770,000 BP, on a landscape unaffected by Wisconsin glaciation. Distinctive scars on the prows of anticlinal ridges at 175-350 m above the valley floor locate the levels of subice meltwater channels. A two-component planar GIS model of the ice surface is derived using these features and intersected with a digital model of contemporary topography to create a glacial limit map. The map is compared to published maps, demonstrating the limits of conventional sediment-based mapping. Additional distinctive meltwater features that were cut during deglaciation are modeled in a similar fashion.

  14. Aquatic insect assemblages associated with subalpine stream segment types in relict glaciated headwaters

    Science.gov (United States)

    Kubo, Joshua S.; Torgersen, Christian E.; Bolton, Susan M.; Weekes, Anne A.; Gara, Robert I.

    2013-01-01

    1. Aquatic habitats and biotic assemblages in subalpine headwaters are sensitive to climate and human impacts. Understanding biotic responses to such perturbations and the contribution of high-elevation headwaters to riverine biodiversity requires the assessment of assemblage composition among habitat types. We compared aquatic insect assemblages among headwater stream segment types in relict glaciated subalpine basins in Mt. Rainier National Park, Washington, USA. 2. Aquatic insects were collected during summer and autumn in three headwater basins. In each basin, three different stream segment types were sampled: colluvial groundwater sources, alluvial lake inlets, and cascade-bedrock lake outlets. Ward's hierarchical cluster analysis revealed high β diversity in aquatic insect assemblages, and non-metric multidimensional scaling indicated that spatial and temporal patterns in assemblage composition differed among headwater stream segment types. Aquatic insect assemblages showed more fidelity to stream segment types than to individual basins, and the principal environmental variables associated with assemblage structure were temperature and substrate. 3. Indicator species analyses identified specific aquatic insects associated with each stream segment type. Several rare and potentially endemic aquatic insect taxa were present, including the recently described species, Lednia borealis (Baumann and Kondratieff). 4. Our results indicate that aquatic insect assemblages in relict glaciated subalpine headwaters were strongly differentiated among stream segment types. These results illustrate the contribution of headwaters to riverine biodiversity and emphasise the importance of these habitats for monitoring biotic responses to climate change. Monitoring biotic assemblages in high-elevation headwaters is needed to prevent the potential loss of unique and sensitive biota.

  15. Models for the runoff from a glaciated catchment area using measurements of environmental isotope contents

    International Nuclear Information System (INIS)

    Behrens, H.; Moser, H.; Oerter, H.; Rauert, W.; Stichler, W.; Ambach, W.; Kirchlechner, P.

    1979-01-01

    For several years, in the glaciated catchment area of the Rofenache (Oetztal Alps, Austria), measurements have been made of the environmental isotopes 2 H, 18 O and 3 H in precipitation, snow and ice samples and in the runoff. Furthermore, the electrolytic conductivity of runoff samples was measured and tracing experiments were made with fluorescent dyes. From core samples drilled in the accumulation area of the Vernagtferner, the gross beta activity was investigated and compared with the data from 2 H, 3 H and 18 O analyses and the data from mass balance studies. It is shown that the annual net balance from previous years can be recovered on temperate glaciers using environmental isotope techniques. From the diurnal variations of the 2 H and 3 H contents and the electrolytic conductivity, the following proportions in the runoff of the Vernagtferner catchment area were obtained during a 24-hour interval at a time of strong ablation (August 1976): about 50% ice meltwater, 25% direct runoff of firn and snow meltwater, and 7% of mineralized groundwater. The rest of the runoff consists of non-mineralized meltwater seeping from the glacier body. The annual variations of the 2 H and 3 H contents in the runoff of the glaciated catchment area permit conclusions on the time sequence of the individual ablation periods, and on the residence time, on the basis of model concepts. The residence times of approximately 100 days or four years, respectively, are obtained from the decrease in the 2 H content at the end of the ablation period and from the variation of the 3 H content in the winter discharge. (author)

  16. Final closure of the Panamaian Isthmus and the onset of northern hemisphere glaciation

    Science.gov (United States)

    Sarnthein, M.; Bartoli, G.; Weinelt, M.; Erlenkeuser, H.; Garbe-Schoenberg, D.; Lea, D. W.

    2005-12-01

    The Greenland ice sheet forms a key factor controlling the Quaternary-style glacial scenario. However, origin and mechanisms of major Arctic glaciation starting at 3.15 Ma and culminating at 2.74 Ma have remained controversial. For this phase of intense cooling Ravelo et al. (2004) proposed a complex gradual forcing mechanism. In contrast, our new submillennial-scale paleoceanographic records from the Pliocene North Atlantic suggest a far more precise timing and forcing for the initiation of northern hemisphere glaciation (NHG), since it was linked to a 2-3 /degC surface water warming during warm stages from 2.95 to 2.82 Ma (until glacial stage G10). These records support previous models (Haug and Tiedemann, 1998) claiming that the final closure of the Panama Isthmus (3.0 - ~2.5 Ma; Groeneveld, 2005) induced an increased poleward salt and heat transport. Associated strengthening of North Atlantic thermohaline circulation and in turn, an intensified moisture supply to northern high latitudes resulted in the build-up of NHG, finally culminating in the great, irreversible climate crash at glacial stage G6 (2.74 Ma). In summary, we see a two-step threshold mechanism that marked the onset of NHG with glacial-to-interglacial cycles quasi-persistent until today. G r o e n e v e l d, J., The final closure of the Central American Seaway. PhD Thesis Kiel, 2005. H a u g, G. and T i e d e m a n n , R., 1 9 9 8. Nature 393, 676-678. R a v e l o , A.C., e t a l ., 2004. Nature 429, 263-267.

  17. Orbital forcing of Arctic climate: mechanisms of climate response and implications for continental glaciation

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, C S [Program in Atmospheric and Oceanic Sciences, Princeton University, NJ 08542, Princeton (United States); Institute for Geophysics, The John A. and Katherine G. Jackson School of Geosciences, The University of Texas at Austin, 4412 Spicewood Springs Rd., Bldg 600, TX 78759, Austin (United States); Broccoli, A J [NOAA/Geophysical Fluid Dynamics Laboratory, NJ 08542, Princeton (United States); Department of Environmental Sciences, Rutgers University, NJ 08903, New Brunswick (United States)

    2003-12-01

    Progress in understanding how terrestrial ice volume is linked to Earth's orbital configuration has been impeded by the cost of simulating climate system processes relevant to glaciation over orbital time scales (10{sup 3}-10{sup 5} years). A compromise is usually made to represent the climate system by models that are averaged over one or more spatial dimensions or by three-dimensional models that are limited to simulating particular ''snapshots'' in time. We take advantage of the short equilibration time ({proportional_to}10 years) of a climate model consisting of a three-dimensional atmosphere coupled to a simple slab ocean to derive the equilibrium climate response to accelerated variations in Earth's orbital configuration over the past 165,000 years. Prominent decreases in ice melt and increases in snowfall are simulated during three time intervals near 26, 73, and 117 thousand years ago (ka) when aphelion was in late spring and obliquity was low. There were also significant decreases in ice melt and increases in snowfall near 97 and 142 ka when eccentricity was relatively large, aphelion was in late spring, and obliquity was high or near its long term mean. These ''glaciation-friendly'' time intervals correspond to prominent and secondary phases of terrestrial ice growth seen within the marine {delta}{sup 18}O record. Both dynamical and thermal effects contribute to the increases in snowfall during these periods, through increases in storm activity and the fraction of precipitation falling as snow. The majority of the mid- to high latitude response to orbital forcing is organized by the properties of sea ice, through its influence on radiative feedbacks that nearly double the size of the orbital forcing as well as its influence on the seasonal evolution of the latitudinal temperature gradient. (orig.)

  18. Atmospheric and oceanic impacts of Antarctic glaciation across the Eocene-Oligocene transition.

    Science.gov (United States)

    Kennedy, A T; Farnsworth, A; Lunt, D J; Lear, C H; Markwick, P J

    2015-11-13

    The glaciation of Antarctica at the Eocene-Oligocene transition (approx. 34 million years ago) was a major shift in the Earth's climate system, but the mechanisms that caused the glaciation, and its effects, remain highly debated. A number of recent studies have used coupled atmosphere-ocean climate models to assess the climatic effects of Antarctic glacial inception, with often contrasting results. Here, using the HadCM3L model, we show that the global atmosphere and ocean response to growth of the Antarctic ice sheet is sensitive to subtle variations in palaeogeography, using two reconstructions representing Eocene and Oligocene geological stages. The earlier stage (Eocene; Priabonian), which has a relatively constricted Tasman Seaway, shows a major increase in sea surface temperature over the Pacific sector of the Southern Ocean in response to the ice sheet. This response does not occur for the later stage (Oligocene; Rupelian), which has a more open Tasman Seaway. This difference in temperature response is attributed to reorganization of ocean currents between the stages. Following ice sheet expansion in the earlier stage, the large Ross Sea gyre circulation decreases in size. Stronger zonal flow through the Tasman Seaway allows salinities to increase in the Ross Sea, deep-water formation initiates and multiple feedbacks then occur amplifying the temperature response. This is potentially a model-dependent result, but it highlights the sensitive nature of model simulations to subtle variations in palaeogeography, and highlights the need for coupled ice sheet-climate simulations to properly represent and investigate feedback processes acting on these time scales. © 2015 The Author(s).

  19. Study of Mechanisms of Aerosol Indirect Effects on Glaciated Clouds: Progress during the Project Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Vaughan T. J.

    2013-10-18

    This 3-year project has studied how aerosol pollution influences glaciated clouds. The tool applied has been an 'aerosol-cloud model'. It is a type of Cloud-System Resolving Model (CSRM) modified to include 2-moment bulk microphysics and 7 aerosol species, as described by Phillips et al. (2009, 2013). The study has been done by, first, improving the model and then performing sensitivity studies with validated simulations of a couple of observed cases from ARM. These are namely the Tropical Warm Pool International Cloud Experiment (TWP-ICE) over the tropical west Pacific and the Cloud and Land Surface Interaction Campaign (CLASIC) over Oklahoma. During the project, sensitivity tests with the model showed that in continental clouds, extra liquid aerosols (soluble aerosol material) from pollution inhibited warm rain processes for precipitation production. This promoted homogeneous freezing of cloud droplets and aerosols. Mass and number concentrations of cloud-ice particles were boosted. The mean sizes of cloud-ice particles were reduced by the pollution. Hence, the lifetime of glaciated clouds, especially ice-only clouds, was augmented due to inhibition of sedimentation and ice-ice aggregation. Latent heat released from extra homogeneous freezing invigorated convective updrafts, and raised their maximum cloud-tops, when aerosol pollution was included. In the particular cases simulated in the project, the aerosol indirect effect of glaciated clouds was twice than of (warm) water clouds. This was because glaciated clouds are higher in the troposphere than water clouds and have the first interaction with incoming solar radiation. Ice-only clouds caused solar cooling by becoming more extensive as a result of aerosol pollution. This 'lifetime indirect effect' of ice-only clouds was due to higher numbers of homogeneously nucleated ice crystals causing a reduction in their mean size, slowing the ice-crystal process of snow production and slowing

  20. A Carboniferous Cabinet of Wonders: an example of how the collaboration of art and Earth Sciences can inspire conservation

    Science.gov (United States)

    Grey, Melissa; Rogers, Janine

    2016-04-01

    The Joggins Fossil Cliffs (Nova Scotia, Canada) is a UNESCO World Heritage Site representing the Late Carboniferous time period (ca. 310-325 mya). The site was formative for Charles Lyell in constructing his geological principles. It is still the best place in the world to view fossils from the Carboniferous 'Coal Age', a time when much of the coal that we use today was formed. The Joggins Fossil Institute is a not-for-profit, charitable organization that co-manages the site with the Province of Nova Scotia. Its mission is to conduct research and educate the public about Earth Sciences through interpretation (e.g., exhibits and tours of the site) and a fossil collection. Fossils are the only direct evidence of how biodiversity has changed over deep time; they are the texts and artifacts that we 'read' in order to understand the development of the earth and that can help humans decipher the deeper histories that produced us. At the Joggins Fossil Institute we primarily present the scientific history of the Carboniferous Period through the use of fossils, but we are also interested in the cultural history of coal production and usage, which is an essential part of the region's economic history. However, this industry has also contributed to climate change and the emergence of a new geological age called the Anthropocene. We encourage our visitors to connect palaeontology and coal energy consumption, and ask them to consider how different values (economic and scientific) are attributed to both coal and fossils; such questions lead directly to discussions about conservation issues. The Joggins Fossil Institute has partnered with the Faculty of Arts at nearby Mount Allison University to create an exhibit that will interrogate these questions. The medium of display that we have chosen is the "cabinet of wonders" or "cabinet of curiosity," which has a rich tradition in western cultures going back to the Renaissance. A venerable intersection of art and science, the cabinet

  1. Regional groundwater flow model for a glaciation scenario. Simpevarp subarea - version 1.2

    International Nuclear Information System (INIS)

    Jaquet, O.; Siegel, P.

    2006-10-01

    A groundwater flow model (glaciation model) was developed at a regional scale in order to study long term transient effects related to a glaciation scenario likely to occur in response to climatic changes. Conceptually the glaciation model was based on the regional model of Simpevarp and was then extended to a mega-regional scale (of several hundred kilometres) in order to account for the effects of the ice sheet. These effects were modelled using transient boundary conditions provided by a dynamic ice sheet model describing the phases of glacial build-up, glacial completeness and glacial retreat needed for the glaciation scenario. The results demonstrate the strong impact of the ice sheet on the flow field, in particular during the phases of the build-up and the retreat of the ice sheet. These phases last for several thousand years and may cause large amounts of melt water to reach the level of the repository and below. The highest fluxes of melt water are located in the vicinity of the ice margin. As the ice sheet approaches the repository location, the advective effects gain dominance over diffusive effects in the flow field. In particular, up-coning effects are likely to occur at the margin of the ice sheet leading to potential increases in salinity at repository level. For the base case, the entire salinity field of the model is almost completely flushed out at the end of the glaciation period. The flow patterns are strongly governed by the location of the conductive features in the subglacial layer. The influence of these glacial features is essential for the salinity distribution as is their impact on the flow trajectories and, therefore, on the resulting performance measures. Travel times and F-factor were calculated using the method of particle tracking. Glacial effects cause major consequences on the results. In particular, average travel times from the repository to the surface are below 10 a during phases of glacial build-up and retreat. In comparison

  2. Regional groundwater flow model for a glaciation scenario. Simpevarp subarea - version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Jaquet, O.; Siegel, P. [Colenco Power Engineering Ltd, Baden-Daettwil (Switzerland)

    2006-10-15

    A groundwater flow model (glaciation model) was developed at a regional scale in order to study long term transient effects related to a glaciation scenario likely to occur in response to climatic changes. Conceptually the glaciation model was based on the regional model of Simpevarp and was then extended to a mega-regional scale (of several hundred kilometres) in order to account for the effects of the ice sheet. These effects were modelled using transient boundary conditions provided by a dynamic ice sheet model describing the phases of glacial build-up, glacial completeness and glacial retreat needed for the glaciation scenario. The results demonstrate the strong impact of the ice sheet on the flow field, in particular during the phases of the build-up and the retreat of the ice sheet. These phases last for several thousand years and may cause large amounts of melt water to reach the level of the repository and below. The highest fluxes of melt water are located in the vicinity of the ice margin. As the ice sheet approaches the repository location, the advective effects gain dominance over diffusive effects in the flow field. In particular, up-coning effects are likely to occur at the margin of the ice sheet leading to potential increases in salinity at repository level. For the base case, the entire salinity field of the model is almost completely flushed out at the end of the glaciation period. The flow patterns are strongly governed by the location of the conductive features in the subglacial layer. The influence of these glacial features is essential for the salinity distribution as is their impact on the flow trajectories and, therefore, on the resulting performance measures. Travel times and F-factor were calculated using the method of particle tracking. Glacial effects cause major consequences on the results. In particular, average travel times from the repository to the surface are below 10 a during phases of glacial build-up and retreat. In comparison

  3. The Sanfengshan copper deposit and early Carboniferous volcanogenic massive sulfide mineralization in the Beishan orogenic belt, Northwestern China

    Science.gov (United States)

    Wang, Jialin; Gu, Xuexiang; Zhang, Yongmei; Zhou, Chao; He, Ge; Liu, Ruiping

    2018-03-01

    The Sanfengshan copper deposit, located in the Beishan orogenic belt, Northwestern China, is hosted in the lower member of the Hongliuyuan Formation, an early Carboniferous metavolcanic-sedimentary sequence. Mineralization occurs as stratiform, stratiform-like and lenticular orebodies, and comprises of laminated, brecciated, banded, massive, and disseminated ores. The mineralogy is dominated by pyrite, chalcopyrite and sphalerite. Fe-Mn chert is widely distributed and generally occurs as massive, laminated, bands or lenses, which are consistent with the orebody. Alteration at Sanfengshan displays a clear concentric zoning pattern and the footwall alteration is more intense and somewhat thicker than the hanging-wall alteration. Systematic geochemical investigation on the volcanic rocks in this area shows that the basalts of the Hongliuyuan Formation (HLY) are predominantly tholeiites with nearly flat rare earth element (REE) pattern, insignificant negative anomalies of high field strength elements (HFSEs), and low Ti/V and Th/Nb ratios. They were most likely derived from partial melting of depleted asthenospheric mantle and formed in a fore-arc setting during initiation of the southward subduction of the Paleo-Asian Ocean. The basalts of the Maotoushan Formation (MTS) display a calc-alkaline nature and are enriched in large ion lithophile elements (LILEs) and depleted in HFSEs, suggesting an active continental margin setting. Sulfur isotope (δ34S) values of the sulfide and sulfate minerals vary between 0‰ and 5.4‰, which are consistent with sulfur derivation from leaching of the host volcanic rocks, although a direct magmatic contribution cannot be ruled out. The Re-Os isotope data of pyrite yield an isochron age of 353 ± 35 Ma, consistent with the age of the host HLY basalts. Thus, a syngenetic (volcanogenic massive sulfide) model is proposed and it is concluded that the Sanfengshan copper deposit is a typical Cyprus-type VMS deposit that formed in an early

  4. Evolution of pores and fractures in an unconventional Upper Carboniferous reservoir analogue, Westphalian D, W-Germany

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, M.; Schurk, K.; Hilgers, C. [RWTH Aachen Univ. (Germany). Reservoir-Petrology, Energy and Mineral Resources Group (EMR); Koehrer, B. [Wintershall Holding GmbH, Barnstorf (Germany); Bertier, P. [RWTH Aachen Univ. (Germany). Inst. of Clay and Interface Mineralogy

    2013-08-01

    Uncertainties in reservoir characterization of tight gas sandstones can be significantly reduced by using quantitative data from outcrops. The active Piesberg quarry near Osnabrueck exposes Upper Carboniferous strata and therefore provides a reservoir outcrop analog to the gas-bearing tight gas fields in NW-Germany. This study focused on variations of sedimentary facies, porosity, diagenesis and structural inventory in the quarry. The Westphalian D strata at Piesberg consist of siliciclastic, coarse- to fine-grained sandstones with a strong cementation, intercalated with coal seams, siltstones and mudstones. Petrography shows shale-, mudstone and clay rip-up fragments squeezed into primary porosity during eodiagenesis. Sandstone types commonly show low porosities (<10 %) and very low permeabilities (<0.01 mD) mainly due to intense quartz cementation. Scarce authigenic carbonates are euhedral ankerites formed during burial. Secondary porosity resulted mostly from detrital carbonate leaching and limited dissolution of feldspars. Within a zone of up to several meters around faults, porosity is much higher. Feldspars are almost completely altered to illite and locally to kaolinite. Partly dissolved detrital carbonates show Fe-oxide margins around intragranular pores, indicative of Fe-rich compositions formed during telo-diagenesis. Both joints and faults were mapped throughout the quarry and strike, slip and throw of the latter were documented. Cemented fractures prevail around faults and may thus be associated with the structural and diagenetic evolution of the Upper Carboniferous of the Piesberg area. This study is embedded into a larger outcrop analog study of RWTH Aachen in cooperation with Wintershall. Its aim is to unravel the impact of structural diagenesis on the alteration and evolution of pore space and thus reservoir quality. Results can be used to develop datadriven exploration strategies and improved development options for analogous subsurface tight gas

  5. A geochemical modelling study of the evolution of the chemical composition of seawater linked to a "snowball" glaciation

    Directory of Open Access Journals (Sweden)

    G. Le Hir

    2008-02-01

    Full Text Available The Snowball Earth theory initially proposed by Kirschvink (1992 to explain the Neoproterozoic glacial episodes, suggested that the Earth was fully ice-covered at 720 Ma (Sturtian episode and 640 Ma (Marinoan episode. This succession of extreme climatic crises induced environmental perturbations which are considered as a strong selective pressure on the evolution of life (Hoffman et al., 1998. Using a numerical model of carbon-alkalinity global cycles, we quantify environmental stresses caused by a global glaciation. According to our results, we suggest that during global glaciations, the ocean becomes acidic (pH~6, and undersaturated with respect to carbonate minerals. Moreover the quick transition from ice-house to greenhouse conditions implies an abrupt and large shift of the oceanic surface temperature which causes an extended hypoxia. The intense continental weathering, in the aftermath of the glaciation, deeply affects the seawater composition inducing rapid changes in terms of pH and alkalinity. We also propose a new timing for post glacial perturbations and for the cap carbonates deposition, ~2 Myr instead of 200 kyr as suggested in a previous modelling study. In terms of Precambrian life sustainability, seawater pH modifications appear drastic all along the glaciation, but we suggest that the buffering action of the oceanic crust dissolution avoids a total collapse of biological productivity. But short-lived and large post-glacial perturbations are more critical and may have played the role of an environmental filter proposed in the classic snowball Earth theory. Although the link between environmental changes and life sustainability cannot be modelled accurately, we suggest that only a permissive life (Knoll, 2003 may explain the relative continuity in microfossils diversity observed before, during and after Neoproterozoic glaciation events.

  6. Advances in Holocene mountain geomorphology inspired by sediment budget methodology

    Science.gov (United States)

    Slaymaker, Olav; Souch, Catherine; Menounos, Brian; Filippelli, Gabriel

    2003-09-01

    The sediment budget, which links sediment sources to sediment sinks with hydroclimatic and weathering processes mediating the response, is applied to the analysis of sediments in three alpine lakes in British Columbia. We provide two ways of using the sediment budget as an integrating device in the interpretation of mountain geomorphology. These approaches differ in their resolution and ability to budget the major components of the fine-sediment cascade in glaciated environments. Taken together, they provide an integrated index of landscape change over the Holocene. The first example compares the hydroclimatic controls of lake sedimentation for the last 600 years (A.D. 1370-1998) preserved in varved sediments from two of the lake basins. This hydroclimatological approach incorporates contemporary monitoring, air photo analysis, and detailed stratigraphy of sedimentation events within a single varve to infer the timing, sources, and preferred pathways of fine-grained sediments reaching the lake basins. The results indicate that glaciers, hillslope, and channel instability within the major subbasins are the principal sediment sources to the lake basins. Transitory sediment storage of glacially derived sediments within the channels is believed to modulate the episodic and more frequent delivery of sediments from adjacent hillslope and fluvial storage sites and direct routing of glacial rock flour during years of prolonged glacial melt. The second example, relying on the phosphorus geochemistry of sediments in an alpine lake basin, considers the evolution of phosphorus forms (from mineral to occluded and organic fractions) as a function of the soil development, inherent slope instability, and repeated cycles of glaciation and neoglaciation over the Holocene. This geochemical approach demonstrates that both neoglaciation and full glaciation have essentially zeroed the system in such a way that a high proportion of mineral phosphorus remains in the present lake sediments

  7. Mountain Biking Injuries.

    Science.gov (United States)

    Ansari, Majid; Nourian, Ruhollah; Khodaee, Morteza

    With the increasing popularity of mountain biking, also known as off-road cycling, and the riders pushing the sport into extremes, there has been a corresponding increase in injury. Almost two thirds of acute injuries involve the upper extremities, and a similar proportion of overuse injuries affect the lower extremities. Mountain biking appears to be a high-risk sport for severe spine injuries. New trends of injury patterns are observed with popularity of mountain bike trail parks and freeride cycling. Using protective gear, improving technical proficiency, and physical fitness may somewhat decrease the risk of injuries. Simple modifications in bicycle-rider interface areas and with the bicycle (bike fit) also may decrease some overuse injuries. Bike fit provides the clinician with postural correction during the sport. In this review, we also discuss the importance of race-day management strategies and monitoring the injury trends.

  8. Current glaciation of the Chikhachev ridge (South-Eastern Altai and its dynamics after maximum of the Little Ice Age

    Directory of Open Access Journals (Sweden)

    D. A. Ganyushkin

    2016-01-01

    Full Text Available Glaciation of the Chikhachev ridge (South-Eastern Altai remains poorly known: field observations were not performed since the mid-twentieth century, available schemes and estimates of the glaciation and its scale made on the basis of remote sensing cover only a part of the glaciers, reconstructions of the Little Ice Age (LIA glaciations are absent. This research was based on interpretation of the satellite images: Landsat-4 (1989, Landsat-7 (2001, and Spot-5 (2011, as well as with the use of data of the field season of 2015. Characteristics of glaciations of the Chikhachev ridge as the whole and of its individual centers (Talduair massif, Mongun-Taiga-Minor massif, and southern part of the Chikhachev ridge were determined for the first time. Recent glaciation is represented by 7 glaciers with their total area of 1.12 km2 in the Talduair massif, by 5 glaciers with total area of 0.75 km2 in the Mongun-Taiga-Minor massif, and by 85 glaciers with total area of 29 km2 in the southern part of the Chikhachev ridge. Since the LIA maximum, areas of glaciers decreased by 61% in the Talduair massif, by 74% in the Mongun-Taiga-Minor massif, by 56% in the southern part of the Chikhachev ridge with simultaneous lifting of the firn line by 50 m, 65 m, and 70 m, respectively.The largest rates of the glacier contractions were determined for the period 1989–2011. Different mechanisms of the glacier retreats were shown by the example of the glacier complexes Burgastyn-Gol (one-sided retreat and disintegration and the Grigorjev glacier (gradual retreat of the tongue. Retreat of the Grigorjev glacier has been reconstructed for the period from the LIA maximum until 2015. Average rate of the retreat increased from 1,6 m/year in 1957–1989 up to 11,3 m/year in 2011–2015. The present-day scales of the glaciers and rates of their retreating do not significantly differ from estimations made by other researchers for the nearest centers of glaciation of the

  9. Numerical simulation of permafrost depth during a future glaciation, Campine area, Northern Belgium

    International Nuclear Information System (INIS)

    Govaerts, Joan; Weetjens, Eef; Beerten, Koen

    2012-01-01

    Document available in extended abstract form only. Given the long time frames involved and their potential detrimental effects, climate changes are considered in the safety assessment of long-term geological disposal of radioactive waste. One such effect that climate changes may govern is the re-appearance of permafrost in north-western Europe. This condition already existed during previous glaciations (e.g., Weichselian glacial, 115-11 ka BP), and may have several consequences for the hydrosphere, geosphere, biosphere and repository. Here, we present calculations of permafrost depth based on the climatic scenario with the Weichselian (last glacial) as an analog to estimate the permafrost depth during a future glaciation. Whereas the lateral extent of permafrost can be deduced from surface features, not much is known about the maximum depth of permafrost during a cold stage in the Campine region. Realistic values of the latent heat of melting of pure water, and thermal conductivity of dry or frozen and unfrozen saturated sand and clay are used as input parameters. In addition, detailed and refined climatic scenarios for the last glacial are used to improve the quality of boundary conditions, together with a more advanced description of freezing/thawing processes. To describe heat transport in the subsoil of the Mol site, the one-dimensional enthalpy conservation equation is used with heat transport only occurring by conduction. In the first calculation case, the temperature at the top of the soil layer is set equal to the air temperatures of a realistic glacial cycle (Weichselian glaciation). In a second calculation case, the insulating effects of the surface cover are considered, and the air temperatures are converted into surface temperatures by making use of the 'n-factor concept', which yields an empirical relationship between the mean annual surface temperature, T s , and the mean annual air temperature, T a . In Figure 1 the permafrost pro-gradation front

  10. Present and past denudation rates in the central Tianshan (Central Asia): impact of the Quaternary glaciations?

    Science.gov (United States)

    Charreau, J.; Puchol, N.; Blard, P.; Braucher, R.; Leanni, L.; Bourles, D. L.; Graveleau, F.; Dominguez, S.

    2012-12-01

    Denudation controls the mass transfer from the uplifting highlands to the lowlands basin. It impacts the isostatic compensation and hence tectonics, the rheology and may drives the Earth climate through its potential impact on atmospheric CO2. Denudation is therefore a key factor governing the evolution of the Earth's surface. Quantitative records of past denudation rates over geological time scales are thus of major importance to untangle the complex interactions between tectonics, climate and surface processes. This is particularly true at the Plio-pleistocene transition where the onset of Quaternary glaciations may have enhanced worldwide denudation rates. The Tianshan stands out as a key area to better address these problems. This range owes its impressive present high topography to the recent deformation due to the India-Asia collision and is moreover sandwiched between two large intracontinental endorheic basins where the total material eroded from the uplifting range may be deciphered from the sedimentary archive. Moreover, here, potential changes in the sediment volume are insensitive to global sea-level variations. Accurate reconstruction of past denudation rate require well-dated sedimentary archives. Over past decades, several magnetostratigraphic studies were carried out in the piedmonts, where remarkable sedimentary sections are exposed in deep rivers entrenchment which expose the thick conglomeratic Xiyu formation, initially assigned to be Plio-pleistocene in age. This led several authors to conclude that, in this region, the sediment fluxes rapidly increaseed at the onset of glaciations. However, absolute magnetostratigraphic dating unambiguously show that this formation is highly diachronous and, therefore, can't owe its origin to a climate change. Given the strong lateral facies variations, reconstruction of past denudation rates from the sedimentary archive require detailed chronostratigraphy and a knowledge of the basin geometry, both almost

  11. Evidence for Multiple Late Quaternary Glaciations in the Southernmost Cordillera Blanca, Peru

    Science.gov (United States)

    Smith, J. A.; Rodbell, D. T.; Ramage, J. M.

    2007-12-01

    Surface-exposure dating with in-situ-produced cosmogenic isotopes has provided the basis for a growing framework of glacial chronologies in the tropical Andes. In the Peruvian Andes, long chronologies (>400 ka) with relatively small local last glacial maximum (LLGM) advances have been reported for the central Cordillera Blanca (ca. 9°30'S) and Junin Plain (11°00'S), whereas preliminary data suggest a shorter record (<40 ka) in the intervening Cordillera Huayhuash (10°15'S). These seemingly contradictory findings raise several questions: Was the LLGM a relatively minor event in the Peruvian Andes, far exceeded by bigger, older advances? Which combination of geographic and geomorphic factors increases the likelihood that evidence of older advances will be preserved? With these questions in mind, we sought a site with both high peaks and a high-altitude plateau. The glaciated Nevado Jeulla Rajo massif (10°00'S, 77°16'W, peaks ca. 5600 masl) marks the southern end of the Cordillera Blanca and the Callejon de Huaylas valley in the central Peruvian Andes. The Conococha Plain (ca. 4050 masl) borders the western side of the massif. Large lateral moraines extend onto the Conococha Plain from the west-facing valleys and multiple moraine loops lie upvalley, closer to active ice margins. Surface-exposure dating (10Be) indicates that the largest lateral moraines from Jeullesh Valley are compound features deposited during the LLGM (ca. 30 ka) and a late-glacial readvance (ca. 16 ka). The LLGM/late-glacial moraines cross-cut an older pair of lateral moraines (ca. 70 ka) that may provide evidence for a smaller advance during marine isotope stage 4. Although the LLGM/late-glacial moraines are impressively large (ca. 150 m high), they do not represent the maximum ice extent in the region. Fluvial outwash deposits beyond the termini of the moraines on the Conococha Plain are underlain by lodgement till that is up to 20 m thick and extends ca. 6 km across the width of the Plain

  12. Clastic sediment flux to tropical Andean lakes: records of glaciation and soil erosion

    Science.gov (United States)

    Rodbell, Donald T.; Seltzer, Geoffrey O.; Mark, Bryan G.; Smith, Jacqueline A.; Abbott, Mark B.

    2008-08-01

    We developed records of clastic sediment flux to 13 alpine lakes in Peru, Ecuador, and Bolivia, and compared these with independently dated records of regional glaciation. Our objectives are to determine whether a strong relationship exists between the extent of ice cover in the region and the rate of clastic sediment delivery to alpine lakes, and thus whether clastic sediment records serve as reliable proxies for glaciation during the late Pleistocene. We isolated the clastic component in lake sediment cores by removing the majority of the biogenic and authigenic components from the bulk sediment record, and we dated cores by a combination of radiocarbon and tephrochronology. In order to partially account for intra-basin differences in sediment focusing, bedrock erosivity, and sediment availability, we normalized each record to the weighted mean value of clastic sediment flux for each respective core. This enabled the stacking of all 13 lake records to produce a composite record that is generally representative of the tropical Andes. There is a striking similarity between the composite record of clastic sediment flux and the distribution of ˜100 cosmogenic radionuclide (CRN) exposure ages for erratics on moraine crests in the central Peruvian and northern Bolivian Andes. The extent of ice cover thus appears to be the primary variable controlling the delivery of clastic sediment to alpine lakes in the region, which bolsters the increasing use of clastic sediment flux as a proxy for the extent of ice cover in the region. The CRN moraine record and the stacked lake core composite record together indicate that the expansion of ice cover and concomitant increase in clastic sediment flux began at least 40 ka, and the local last glacial maximum (LLGM) culminated between 30 and 20 ka. A decline in clastic sediment flux that began ˜20 ka appears to mark the onset of deglaciation from the LLGM, at least one millennium prior to significant warming in high latitude regions

  13. How Strong is the Case for Proterozoic Low-Latitude Glaciation?

    Science.gov (United States)

    Evans, D. A.

    2004-05-01

    The most recent global compilations of paleomagnetic depositional latitudes for Proterozoic glaciogenic formations indicate a dominant mode near the paleo-equator (Evans 2000 AJS; Evans 2003 Tectonophysics). This result would therefore support either the snowball Earth or the large-obliquity hypotheses for Precambrian ice ages, but would reject the uniformitarian comparison to polar-temperate-restricted Phanerozoic glaciogenic deposits. The most reliable low-latitude results come from the Australian Marinoan succession, but a recent summary of these units has suggested that a glaciogenic origin is not yet demonstrated (Eyles and Januszczak 2004 Earth-Sci Reviews). It becomes useful, then, to review the global evidence for Proterozoic low-latitude glaciation. Eyles and Januszczak (ibid.) identified 13 Neoproterozoic deposits with "demonstrated" glacial influence. Among these, poor age constraints and lack of paleomagnetic data prohibit estimation of depositional paleolatitudes for the Fiq, Sturtian, Vreeland, Taoudeni, East Greenland, Port Askaig, and Zhengmuguan units. Moderate paleolatitudes are reasonably well supported for the South China, Gaskiers, Smalfjord, and Moelv units. Among the three remaining units, the Rapitan Group can be assigned a near-equatorial paleolatitude indirectly through use of the Galeros and Franklin-Natkusiak paleomagnetic results, as long as the Rapitan age lies within 750-720 Ma as generally expected. The Moonlight Valley Formation in northern Australia may be assigned a tropical paleolatitude according to high-quality paleomagnetic results from compellingly correlated Marinoan strata in southern Australia. Those strata, including the famous Elatina Formation, have yielded a robust paleomagnetic signature that is commonly interpreted to imply frigid climate (manifest in part by frost-wedge polygons) at near-equatorial latitudes. Concerns that the Neoproterozoic geomagnetic field was either nonaxial or nondipolar are valid in principle

  14. Chemotaxonomy for naturally macerated tree-fern cuticles (Medullosales and Marattiales), Carboniferous Sydney and Mabou Sub-Basins, Nova Scotia, Canada

    Science.gov (United States)

    Zodrow, E.L.; Mastalerz, Maria

    2001-01-01

    Naturally macerated cuticles (NMC) and one synangium, representing medullosalean and marattialean tree-fern species, from two Carboniferous coalfields in Nova Scotia, Canada, are investigated. The samples were analyzed by infrared spectroscopy (FTIR), and by pyrolysis-gas chromatograph/mass spectrometry (py-Gc/Ms) techniques in search for chemical signatures that would help in developing a chemotaxonomic classification of Carboniferous fern species, assuming genetically dependent make-up of cuticles. FTIR-derived CH2/CH3 ratios, in conjunction with contributions from carboxyl groups, demonstrated a better potential for discriminating between medullosalean genera and species than molecular signatures obtained by py-Gc/Ms. However, the latter provided better data for differentiating medullosalean from marattialean tree ferns as a group. Changes in the chemical make-up of naturally macerated cuticles due to sample preparation are discussed. ?? 2001 Elsevier Science B.V. All rights reserved.

  15. Chemotaxonomy for naturally macerated tree-fern cuticles (Medullosales and Marattiales), Carboniferous Sydney and Mabou Sub-Basins, Nova Scotia, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Zodrow, Erwin L. [Department of Earth Sciences, University College of Cape Breton, PO Box 5300, Nova Scotia, B1P 6L2 Sydney (Canada); Mastalerz, Maria [Indiana Geological Survey, Indiana University, 611 North Walnut Grove, 47405-2208 Bloomington, IN (United States)

    2001-07-01

    Naturally macerated cuticles (NMC) and one synangium, representing medullosalean and marattialean tree-fern species, from two Carboniferous coalfields in Nova Scotia, Canada, are investigated. The samples were analyzed by infrared spectroscopy (FTIR), and by pyrolysis-gas chromatograph/mass spectrometry (py-Gc/Ms) techniques in search for chemical signatures that would help in developing a chemotaxonomic classification of Carboniferous fern species, assuming genetically dependent make-up of cuticles. FTIR-derived CH{sub 2}/CH{sub 3} ratios, in conjunction with contributions from carboxyl groups, demonstrated a better potential for discriminating between medullosalean genera and species than molecular signatures obtained by py-Gc/Ms. However, the latter provided better data for differentiating medullosalean from marattialean tree ferns as a group. Changes in the chemical make-up of naturally macerated cuticles due to sample preparation are discussed.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  17. Carboniferous - Early Permian magmatic evolution of the Bogda Range (Xinjiang, NW China): Implications for the Late Paleozoic accretionary tectonics of the SW Central Asian Orogenic Belt

    Science.gov (United States)

    Wali, Guzalnur; Wang, Bo; Cluzel, Dominique; Zhong, Linglin

    2018-03-01

    The Late Paleozoic magmatic evolution of the Bogda Range (Chinese North Tianshan) is important for understanding the accretionary history of the Central Asian Orogenic Belt. We investigated the Carboniferous and Lower Permian volcanic and sedimentary sequences of the Daheyan section, southern Bogda Range, and present new zircon U-Pb ages and whole-rock geochemical data for the volcanic rocks. One Carboniferous rhyolite is dated at 298 ± 8 Ma; a Permian basalt yielded many Proterozoic zircon xenocrysts, and its maximum age (∼297 Ma) is constrained by the detrital zircon ages of the sandstone that stratigraphically underlies it. These volcanic rocks belong to calc-alkaline series. We further synthesize previous geochronological, geochemical and isotopic data of magmatic and sedimentary rocks in the Bogda Range. The available data indicate that the magmatism occurred continuously from 350 Ma to 280 Ma. A comprehensive analysis allows us to propose that: (1) the Carboniferous to Early Permian magmatic rocks of the Bogda Range generally show consistent arc-type features; (2) increasing mantle input through time suggests intra-arc extension in a supra-subduction zone; (3) the localized occurrence of Early Permian alkaline pillow basalts and deep water sediments close to the major shear zone advocate a transtensional crustal thinning during the transition from Carboniferous convergence to Early Permian transcurrent tectonics; (4) occurrence of a large number of Proterozoic zircon xenocrysts in the Late Paleozoic magmatic rocks, and Proterozoic detrital zircons in the coeval clastic sediments suggest a continental or transitional basement of the Bogda Arc; (5) subduction in the Bogda area terminated prior to the deposition of Middle Permian terrestrial sediments.

  18. Retrowedge-related Carboniferous units and coeval magmatism in the northwestern Neuquén province, Argentina

    Science.gov (United States)

    Zappettini, Eduardo O.; Chernicoff, Carlos J.; Santos, Joao O. S.; Dalponte, Marcelo; Belousova, Elena; McNaughton, Neal

    2012-11-01

    The studied Carboniferous units comprise metasedimentary (Guaraco Norte Formation), pyroclastic (Arroyo del Torreón Formation), and sedimentary (Huaraco Formation) rocks that crop out in the northwestern Neuquén province, Argentina. They form part of the basement of the Neuquén Basin and are mostly coeval with the Late Paleozoic accretionary prism complex of the Coastal Cordillera, south-central Chile. U-Pb SHRIMP dating of detrital zircon yielded a maximum depositional age of 374 Ma (Upper Devonian) for the Guaraco Norte Formation and 389 Ma for the Arroyo del Torreón Formation. Detrital magmatic zircon from the Guaraco Norte Formation are grouped into two main populations of Devonian and Ordovician (Famatinian) ages. In the Arroyo del Torreón Formation, zircon populations are also of Devonian and Ordovician (Famatinian), as well as of Late Neoproterozoic and Mesoproterozoic ages. In both units, there is a conspicuous population of Devonian magmatic zircon grains (from 406 ± 4 Ma to 369 ± 5 Ma), indicative of active magmatism at that time range. The ɛHf values of this population range between -2.84 and -0.7, and the TDM-(Hf) are mostly Mesoproterozoic, suggesting that the primary sources of the Devonian magmatism contained small amounts of Mesoproterozoic recycled crustal components. The chemical composition of the Guaraco Norte Formation corresponds to recycled, mature polycyclic sediment of mature continental provenance, pointing to a passive margin with minor inputs from continental margin magmatic rocks. The chemical signature of the Huaraco Formation indicates that a magmatic arc was the main provenance for sediments of this unit, which is consistent with the occurrence of tuff—mostly in the Arroyo del Torreón Formation and very scarcely in the Huaraco Formation—with a volcanic-arc signature, jointly indicating the occurrence of a Carboniferous active arc magmatism during the deposition of the two units. The Guaraco Norte Formation is interpreted

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

    Science.gov (United States)

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

    2004-01-01

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

  20. Global snowline and mountain topography: a contrasted view

    Science.gov (United States)

    Champagnac, Jean-Daniel; Herman, Frédéric; Valla, Pierre

    2013-04-01

    The examination of the relationship between Earth's topography and present and past climate (i.e., long-term elevation of glaciers Equilibrium Line Altitude) reveals that the elevation of mountain ranges may be limited or controlled by glaciations (e.g. Porter, 1989). This is of prime importance, because glacial condition would lead to a limit the mountain development, hence the accumulation of gravitational energy and prevent the development of further glacial conditions as well as setting the erosion in (peri)glacial environments. In this study, we examine the relationships between topography and the global Equilibrium Line Altitude of alpine glaciers around the world (~ long term snowline, i.e. the altitude where the ice mass balance is null). This analysis reinforce a global study previously published (Champagnac et al., 2012), and provide a much finer view of the climate-topography-tectonics relationships. Specifically, two main observations can be drawn: 1) The distance between the (averaged and maximum) topography, and the ELA decreases pole ward the poles, and even become reversed (mean elevation above to ELA) at high latitude. Correlatively, the elevation of very large portion of land at mid-latitude cannot be related to glaciations, simply because it was never glaciated (large distance between topography and long-term mean ELA). The maximum distance between the ELA and the topography is greater close to the equator and decreases poleward. In absence of glacial and periglacial erosion, this trend cannot have its origin in glacial and periglacial processes. Moreover, the ELA elevation shows a significant (1000~1500m) depression in the intertropical zone. This depression of the ELA is not reflected at all in the topography 2) The distribution of relief on Earth, if normalized by the mean elevation of mountain ranges (as a proxy for available space to create relief, see Champagnac et al., 2012 for details) shows a latitudinal band of greater relief between

  1. Mountain-Plains Curriculum.

    Science.gov (United States)

    Mountain-Plains Education and Economic Development Program, Inc., Glasgow AFB, MT.

    The document lists the Mountain-Plains curriculum by job title (where applicable), including support courses. The curriculum areas covered are mathematics skills, communication skills, office education, lodging services, food services, marketing and distribution, welding support, automotive, small engines, career guidance, World of Work, health…

  2. Injuries in mountain biking.

    Science.gov (United States)

    Gaulrapp, H; Weber, A; Rosemeyer, B

    2001-01-01

    Despite still growing attraction mountain biking as a matter of sports traumatology still lacks relevant data based on large cross-sectional surveys. To obtain an overview of risk factors, types, and main body sites of injuries occurring in mountain biking we assessed the results of a questionnaire answered by 3873 athletes. A total of 8133 single lesions were reported by 3474 athletes, 36% of whom regularly participated in competitions. The incidence of injuries in mountain biking is comparable to that in other outdoor sports, the majority of injuries being minor. Mountain biking athletes were found to have an overall injury risk rate of 0.6% per year and 1 injury per 1000 h of biking. The main risk factors included slippery road surface, cyclist's poor judgement of the situation, and excessive speed, representing personal factors that could be altered by preventive measures. Of all injuries 14% were due to collision with some part of the bike, especially the pedals and the handlebar. While 75% of the injuries were minor, such as skin wounds and simple contusions, 10% were so severe that hospitalization was required. A breakdown of the injuries according to body site and frequency of occurrence is presented.

  3. Rocky Mountain Riparian Digest

    Science.gov (United States)

    Deborah M. Finch

    2008-01-01

    The Rocky Mountain Riparian Digest presents the many facets of riparian research at the station. Included are articles about protecting the riparian habitat, the social and economic values of riparian environments, watershed restoration, remote sensing tools, and getting kids interested in the science.

  4. Rocky Mountain High.

    Science.gov (United States)

    Hill, David

    2001-01-01

    Describes Colorado's Eagle Rock School, which offers troubled teens a fresh start by transporting them to a tuition- free campus high in the mountains. The program encourages spiritual development as well as academic growth. The atmosphere is warm, loving, structured, and nonthreatening. The article profiles several students' experiences at the…

  5. Large-scale evolution of the central-east Greenland margin: New insights to the North Atlantic glaciation history

    Science.gov (United States)

    Pérez, Lara F.; Nielsen, Tove; Knutz, Paul C.; Kuijpers, Antoon; Damm, Volkmar

    2018-04-01

    The continental shelf of central-east Greenland is shaped by several glacially carved transverse troughs that form the oceanward extension of the major fjord systems. The evolution of these troughs through time, and their relation with the large-scale glaciation of the Northern Hemisphere, is poorly understood. In this study seismostratigraphic analyses have been carried out to determine the morphological and structural development of this important sector of the East Greenland glaciated margin. The age of major stratigraphic discontinuities has been constrained by a direct tie to ODP site 987 drilled in the Greenland Sea basin plain off Scoresby Sund fan system. The areal distribution and internal facies of the identified seismic units reveal the large-scale depositional pattern formed by ice-streams draining a major part of the central-east Greenland ice sheet. Initial sedimentation along the margin was, however, mainly controlled by tectonic processes related to the margin construction, continental uplift, and fluvial processes. From late Miocene to present, progradational and erosional patterns point to repeated glacial advances across the shelf. The evolution of depo-centres suggests that ice sheet advances over the continental shelf have occurred since late Miocene, about 2 Myr earlier than previously assumed. This cross-shelf glaciation is more pronounced during late Miocene and early Pliocene along Blosseville Kyst and around the Pliocene/Pleistocene boundary off Scoresby Sund; indicating a northward migration of the glacial advance. The two main periods of glaciation were separated by a major retreat of the ice sheet to an inland position during middle Pliocene. Mounded-wavy deposits interpreted as current-related deposits suggest the presence of changing along-slope current dynamics in concert with the development of the modern North Atlantic oceanographic pattern.

  6. Tropical/Subtropical Peatland Development and Global CH4 during the Last Glaciation.

    Science.gov (United States)

    Xu, Hai; Lan, Jianghu; Sheng, Enguo; Liu, Yong; Liu, Bin; Yu, Keke; Ye, Yuanda; Cheng, Peng; Qiang, Xiaoke; Lu, Fengyan; Wang, Xulong

    2016-07-28

    Knowledge of peatland development over the tropical/subtropical zone during the last glaciation is critical for understanding the glacial global methane cycle. Here we present a well-dated 'peat deposit-lake sediment' alternate sequence at Tengchong, southwestern China, and discuss the peatland development and its linkage to the global glacial methane cycle. Peat layers were formed during the cold Marine Isotope Stage (MIS)-2 and -4, whereas lake sediments coincided with the relatively warm MIS-3, which is possibly related to the orbital/suborbital variations in both temperature and Asian summer monsoon intensity. The Tengchong peatland formation pattern is broadly synchronous with those over subtropical southern China and other tropical/subtropical areas, but it is clearly in contrast to those over the mid-high Northern Hemisphere. The results of this work suggest that the shifts of peatland development between the tropical/subtropical zone and mid-high Northern Hemisphere may have played important roles in the glacial/interglacial global atmospheric CH4 cycles.

  7. Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

    Science.gov (United States)

    Menezes, Riya C.; Jayarajan, Aditi; Shanker, Kartik

    2016-01-01

    The historical processes underlying high diversity in tropical biodiversity hotspots like the Western Ghats of Peninsular India remain poorly understood. We sampled bush frogs on 13 massifs across the Western Ghats Escarpment and examined the relative influence of Quaternary glaciations, ecological gradients and geological processes on the spatial patterns of lineage and clade diversification. The results reveal a large in situ radiation (more than 60 lineages), exhibiting geographical structure and clade-level endemism, with two deeply divergent sister clades, North and South, highlighting the biogeographic significance of an ancient valley, the Palghat Gap. A majority of the bush frog sister lineages were isolated on adjacent massifs, and signatures of range stasis provide support for the dominance of geological processes in allopatric speciation. In situ diversification events within the montane zones (more than 1800 m) of the two highest massifs suggest a role for climate-mediated forest-grassland persistence. Independent transitions along elevational gradients among sub-clades during the Miocene point to diversification along the elevational gradient. The study highlights the evolutionary significance of massifs in the Western Ghats with the high elevations acting as centres of lineage diversification and the low- and mid-elevations of the southern regions, with deeply divergent lineages, serving as museums. PMID:27534957

  8. Some aspects of the last glaciation in the Mazury Lake District (north-eastern Poland

    Directory of Open Access Journals (Sweden)

    Pochocka-Szwarc Katarzyna

    2013-06-01

    Full Text Available The morphology of the Mazury Lake District (north-eastern Poland dates from 24-19 ka (main stadial of the youngest Vistulian glaciation. During this last glacial maximum (MIS 2 a belt with lacustrine basins was formed when the ice sheet retreated at the end of the Pomeranian phase. The ice-sheet retreat is morphologically also expressed by the occurrence of end moraines. The study area is situated in the Skaliska Basin, in the northern part of the Lake District (near the Polish/ Russian border, at the periphery of zone with end moraines. Originally the basin was an ice-dammed depression filled with melt water; the water flowed out into the developing Pregoła valley when the ice retreated and did no longer dam off the depression. The basin, which is surrounded by hill-shaped moraines, is filled now with Late Glacial and Holocene glaciolacustrine sediments. The organic sediments of the basin record the history of the Late Glacial and Holocene climatic changes in this region.

  9. Export of nutrient rich Northern Component Water preceded early Oligocene Antarctic glaciation

    Science.gov (United States)

    Coxall, Helen K.; Huck, Claire E.; Huber, Matthew; Lear, Caroline H.; Legarda-Lisarri, Alba; O'Regan, Matt; Sliwinska, Kasia K.; van de Flierdt, Tina; de Boer, Agatha M.; Zachos, James C.; Backman, Jan

    2018-03-01

    The onset of the North Atlantic Deep Water formation is thought to have coincided with Antarctic ice-sheet growth about 34 million years ago (Ma). However, this timing is debated, in part due to questions over the geochemical signature of the ancient Northern Component Water (NCW) formed in the deep North Atlantic. Here we present detailed geochemical records from North Atlantic sediment cores located close to sites of deep-water formation. We find that prior to 36 Ma, the northwestern Atlantic was stratified, with nutrient-rich, low-salinity bottom waters. This restricted basin transitioned into a conduit for NCW that began flowing southwards approximately one million years before the initial Antarctic glaciation. The probable trigger was tectonic adjustments in subarctic seas that enabled an increased exchange across the Greenland-Scotland Ridge. The increasing surface salinity and density strengthened the production of NCW. The late Eocene deep-water mass differed in its carbon isotopic signature from modern values as a result of the leakage of fossil carbon from the Arctic Ocean. Export of this nutrient-laden water provided a transient pulse of CO2 to the Earth system, which perhaps caused short-term warming, whereas the long-term effect of enhanced NCW formation was a greater northward heat transport that cooled Antarctica.

  10. Sequence stratigraphy from ``spot'' outcrops—example from a carbonate-dominated setting: Devonian-Carboniferous transition, Dinant synclinorium (Belgium)

    Science.gov (United States)

    Van Steenwinkel, M.

    1990-12-01

    The application of sequence stratigraphy appears to be perfectly valid in isolated "spot" outcrops, which usually are badly exposed and located in areas of strong tectonic overprint. The case study presented here is in a carbonate-dominated setting at the northern edge of the Cornwall-Rhenish basin, during latest Devonian and earliest Carboniferous times. The approach taken involved the analysis of facies and vertical facies evolutions, in combination with detailed biostratigraphy. The subsequent deduction of deepening and shallowing events, and the understanding of the sedimentary response to these events in different palaeogeographical positions, are the basis for lateral correlation of facies sequences. A similar trend in the changes of deepenings and shallowings throughout the area, regardless of lateral facies differentiation, indicates a relationship between bathymetric changes and relative sea-level changes, that is independent of local differences in the sedimentation or subsidence rates. The studied stratigraphic interval, with its apparently "abrupt" changes in facies or lithology, is the sedimentary response to six, gradually changing trends in the rate of relative sea-level fall and rise. End-Devonian, offshore highstand deposits (1) are capped by an unconformity surface or by a surface of submarine erosion and nondeposition, representing a sequence boundary (2). The overlying lowstand unit consists of a basal (3) and an upper (4) part. The basal part contains an oolitic and crinoidal sand shoals, associated with a transgressive lag deposit in offshore position; the upper, main part is a prograding wedge of shallow-marine crinoidal sands, intercalated with increasingly deeper-water shaly facies (higher-order fluctuation). This lowstand unit was deposited during the initial, slow phase of relative sea-level rise. It levelled the topographic relief before the final drowning during the subsequent rapid (near the rise inflection point) relative sea

  11. Mountains: top down.

    Science.gov (United States)

    Woodwell, George M

    2004-11-01

    Mountainous regions offer not only essential habitat and resources, including water, to the earth's more than 6 billion inhabitants, but also insights into how the global human habitat works, how it is being changed at the moment as global climates are disrupted, and how the disruption may lead to global biotic and economic impoverishment. At least 600 million of the earth's more than 6 billion humans dwell in mountainous regions. Such regions feed water into all the major rivers of the world whose valleys support most of the rest of us. At least half of the valley dwellers receive part or all of their water from montane sources, many from the melt water of glaciers, others from the annual snow melt. Glaciers are retreating globally as the earth warms as a result of human-caused changes in the composition of the atmosphere. Many are disappearing, a change that threatens municipal water supplies virtually globally. The warming is greatest in the higher latitudes where the largest glaciers such as those of Greenland and the Antarctic Continent have become vulnerable. The melting of ice in the northern hemisphere raises serious concerns about the continued flow of the Gulf Stream and the possibility of massive climatic changes in Scandinavia and northern Europe. Mountains are also biotic islands in the sea life, rich in endemism at the ecotype level. The systematic warming of the earth changes the environment out from under these genetically specialized strains (ecotypes) which are then maladapted and vulnerable to diseases of all types. The process is systematic impoverishment in the pattern conspicuous on mountain slopes with increasing exposure to climatic extremes. It is seen now in the increased mortality and morbidity of plants as climatic changes accumulate. The seriousness of the global climatic disruption is especially clear in any consideration of mountains. It can and must be addressed constructively despite the adamancy of the current US administration.

  12. Glacier Monitoring and Capacity Building: Important Ingredients for Sustainable Mountain Development

    Directory of Open Access Journals (Sweden)

    Samuel U. Nussbaumer

    2017-02-01

    Full Text Available Glacier observation data from major mountain regions of the world are key to improving our understanding of glacier changes: they deliver fundamental baseline information for climatological, hydrological, and hazard assessments. In many mountain ecosystems, as well as in the adjacent lowlands, glaciers play a crucial role in freshwater provision and regulation. This article first presents the state of the art on glacier monitoring and related strategies within the framework of the Global Terrestrial Network for Glaciers (GTN-G. Both in situ measurements of changes in glacier mass, volume, and length as well as remotely sensed data on glacier extents and changes over entire mountain ranges provide clear indications of climate change. Based on experiences from capacity-building activities undertaken in the Tropical Andes and Central Asia over the past years, we also review the state of the art on institutional capacity in these regions and make further recommendations for sustainable mountain development. The examples from Peru, Ecuador, Colombia, and Kyrgyzstan demonstrate that a sound understanding of measurement techniques and of the purpose of measurements is necessary for successful glacier monitoring. In addition, establishing durable institutions, capacity-building programs, and related funding is necessary to ensure that glacier monitoring is sustainable and maintained in the long term. Therefore, strengthening regional cooperation, collaborating with local scientists and institutions, and enhancing knowledge sharing and dialogue are envisaged within the GTN-G. Finally, glacier monitoring enhances the resilience of the populations that depend on water resources from glacierized mountains or that are affected by hazards related to glacier changes. We therefore suggest that glacier monitoring be included in the development of sustainable adaptation strategies in regions with glaciated mountains.

  13. THE GLACIER COMPLEXES OF THE MOUNTAIN MASSIFS OF THE NORTH-WEST OF INNER ASIA AND THEIR DYNAMICS

    Directory of Open Access Journals (Sweden)

    Kirill Chistyakov

    2011-01-01

    Full Text Available The subject of this paper is the glaciation of the mountain massifs Mongun-Taiga, Tavan-Boghd-Ola, Turgeni-Nuru, and Harhira-Nuru. The glaciation is represented mostly by small forms that sometimes form a single complex of dome-shaped peaks. According to the authors, the modern glaciated area of the mountain massifs is 21.2 km2(Tavan-Boghd-Ola, 20.3 km2 (Mongun-Taiga, 42 km2 (Turgeni-Nuru, and 33.1 km2 (Harhira-Nuru. The area of the glaciers has been shrinking since the mid 1960’s. In 1995–2008, the rate of reduction of the glaciers’ area has grown considerably: valley glaciers were rapidly degrading and splitting; accumulation of morainic material in the lower parts of the glaciers accelerated. Small glaciers transformed into snowfields and rock glaciers. There has been also a degradation of the highest parts of the glaciers and the collapse of the glacial complexes with a single zone of accumulation into isolated from each other glaciers. Reduced snow cover area has led to a rise in the firn line and the disintegration of a common accumulation area of the glacial complex. In the of the Mongun-Taiga massif, in 1995–2008, the firn line rose by 200–300 m. The reduction of the glaciers significantly lagged behind the change in the position of the accumulation area boundary. In the past two years, there has been a significant recovery of the glaciers that could eventually lead to their slower degradation or stabilization of the glaciers in the study area.

  14. Late Carboniferous porphyry copper mineralization at La Voluntad, Neuquén, Argentina: Constraints from Re-Os molybdenite dating

    Science.gov (United States)

    Garrido, Mirta; Barra, Fernando; Domínguez, Eduardo; Ruiz, Joaquin; Valencia, Victor A.

    2008-07-01

    The La Voluntad porphyry Cu-Mo deposit in Neuquén, Argentina, is one of several poorly known porphyry-type deposits of Paleozoic to Early Jurassic age in the central and southern Andes. Mineralization at La Voluntad is related to a tonalite porphyry from the Chachil Plutonic Complex that intruded metasedimentary units of the Piedra Santa Complex. Five new Re-Os molybdenite ages from four samples representing three different vein types (i.e., quartz-molybdenite, quartz-sericite-molybdenite and quartz-sericite-molybdenite ± chalcopyrite-pyrite) are identical within error and were formed between ~312 to ~316 Ma. Rhenium and Os concentrations range between 34 to 183 ppm and 112 to 599 ppb, respectively. The new Re-Os ages indicate that the main mineralization event at La Voluntad, associated to sericitic alteration, was emplaced during a time span of 1.7 ± 3.2 Ma and that the deposit is Carboniferous in age, not Permian as previously thought. La Voluntad is the oldest porphyry copper deposit so far recognized in the Andes and indicates the presence of an active magmatic arc, with associated porphyry style mineralization, at the proto-Pacific margin of Gondwana during the Early Pennsylvanian.

  15. Organic petrology and geochemistry of the Carboniferous coal seams from the Central Asturian Coal Basin (NW Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Piedad-Sanchez, Noe; Martinez, Luis; Izart, Alain; Elie, Marcel [UMR G2R/7566, Geologie et Gestion des Ressources Minerales et Energetiques, Faculte des Sciences, Universite Henri Poincare, Nancy 1, BP-239, Boulevard des Aiguillettes, Vandoeuvre-les-Nancy Cedex 54506 (France); Suarez-Ruiz, Isabel [Instituto Nacional del Carbon (CSIC), C/ Francisco Pintado Fe, 26, Ap. Co., 73, Oviedo 33011 (Spain); Keravis, Didier [Institut des Sciences de la Terre (ISTO), CNRS-Universite d' Orleans, Batiment Geosciences, BP 6759, Orleans 45067 (France)

    2004-03-23

    This paper presents for the first time a petrological and geochemical study of coals from the Central Asturian Coal Basin (North Spain) of Carboniferous (Pennsylvanian), mainly of Moscovian, age. A paleoenvironmental approach was used, taking into account both petrographic and organic geochemical studies. Vitrinite reflectance (R{sub r}) ranges from 0.5% to 2.5%, which indicates a high volatile bituminous to semianthracite and anthracite coal rank. The coal samples selected for paleoenvironmental reconstruction are located inside the oil-gas-prone phase, corresponding to the interval between the onset of oil generation and first gas generation and efficient expulsion of oil. This phase is represented by coals that have retained their hydrocarbon potential and also preserved biomarker information. Paleodepositional reconstruction based on maceral and petrographic indices points to a swamp environment with vitrinite-rich coal facies and variable mineral matter content. The gelification index (GI) and groundwater influence index (GWI) indicate strong gelification and wet conditions. The biomarkers exhibit a high pristane/phytane ratio, suggesting an increase in this ratio from diagenetic processes, and a high diterpanes ratio. This, in turn, would seem to indicate a high swamp water table and a humid climate. The maximum point of coal accumulation occurred during the regressive part of the Late Moscovian sequence and in the most humid climate described for this period of time in the well-known coal basins of Europe and North America.

  16. Carboniferous high-pressure metamorphism of Ordovician protoliths in the Argentera Massif (Italy), Southern European Variscan belt

    Science.gov (United States)

    Rubatto, Daniela; Ferrando, Simona; Compagnoni, Roberto; Lombardo, Bruno

    2010-04-01

    The age of high-pressure metamorphism is crucial to identify a suitable tectonic model for the vast Variscan orogeny. Banded H P granulites from the Gesso-Stura Terrain in the Argentera Massif, Italy, have been recently described (Ferrando et al., 2008) relicts of high-pressure metamorphism in the western part of the Variscan orogen. Bulk rock chemistry of representative lithologies reveals intermediate silica contents and calc-alkaline affinity of the various cumulate layers. Enrichment in incompatible elements denotes a significant crustal component in line with intrusion during Ordovician rifting. Magmatic zircon cores from a Pl-rich layer yield scattered ages indicating a minimum protolith age of 486 ± 7 Ma. Carboniferous zircons (340.7 ± 4.2 and 336.3 ± 4.1 Ma) are found in a Pl-rich and a Pl-poor layer, respectively. Their zoning, chemical composition (low Th/U, flat HREE pattern and Ti-in-zircon temperature) and deformation indicate that they formed during the high-pressure event before decompression and mylonitisation. The proposed age for high-pressure metamorphism in the Argentera Massif proves that subduction preceded anatexis by less than 20 Ma. The new data allow a first-order comparison with the Bohemian Massif, which is located at the eastern termination of the Variscan orogen. Similarities in evolution at either end of the orogen support a Himalayan-type tectonic model for the entire European Variscides.

  17. Geochemistry and 40Ar/39Ar age of Early Carboniferous dolerite sills in the southern Baltic Sea

    Directory of Open Access Journals (Sweden)

    Gediminas Motuza

    2015-08-01

    Full Text Available The Early Carboniferous magmatic event in the southern Baltic Sea is manifested by dolerite intrusions. The presumable area in which the dolerite intrusions occur ranges from 30 to 60 km in east–west direction, and is about 100 km in north–south direction. The dolerites were sampled in well D1-1 and investigated by applying chemical analysis and 40Ar/39Ar step-heating dating. Dolerites are classified as alkali and sodic, characterized by high TiO2 (3.92, 3.99 wt% and P2O5 (1.67, 1.77 wt% and low MgO (4.89, 4.91 wt% concentrations, enriched in light rare earth elements, originated from an enriched mantle magma source and emplaced in a continental rift tectonic setting. The 351 ± 11 Ma 40Ar/39Ar plateau age for groundmass plagioclase indicates a considerable age gap with the 310–250 Ma magmatism in southern Scandinavia and northern Germany. The magmatic rocks in the Baltic Sedimentary Basin are coeval with alkaline intrusions of NE Poland. Both magmatic provinces lie in the northwestward prolongation of the Pripyat–Dnieper–Donetsk Rift (370–359 Ma and may constitute a later phase of magmatic activity of this propagating rift system.

  18. Results and synthesis of integrated geologic studies of the carboniferous Lisburne Group of Northeastern Alaska. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Watts, K.F.

    1995-05-01

    The primary objective of this project was to develop an integrated database to characterize reservoir heterogeneities resulting from numerous small-scale shallowing-upward cycles (parasequences) comprising the Pennsylvanian Wahoo 1imestone. The Wahoo Limestone is the upper part of an extensive carbonate platform sequence of the Carboniferous Lisburne Group which is widely exposed in the Brooks Range and is a widespread hydrocarbon reservoir unit in the subsurface of the North Slope of Alaska. A leading goal is to determine lateral and vertical variations in the complex mosaic of carbonate facies comprising the Wahoo. Aspects of rock units adjacent to the Wahoo, the underlying Endicott Group and Alapah Limestone and overlying Echooka Formation are also discussed. This report includes an overview of the regional geological framework; a discussion of biostratigraphic results; a summary of diagenetic studies; and preliminary results of comparative studies of a cored well in the Lisburne oil field. A computerized database system (the Wahoo database) was developed and is explained in a users manual. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  19. Evidence of a low-latitude glacial buzzsaw: Progressive hypsometry reveals height-limiting glacial erosion in tropical mountain belts

    Science.gov (United States)

    Cunningham, M.; Stark, C. P.; Kaplan, M. R.; Schaefer, J. M.; Winckler, G.

    2017-12-01

    It has been widely demonstrated that glacial erosion limits the height of mid-latitude mountain ranges—a phenomenon commonly referred to as the "glacial buzzsaw." The strength of the buzzsaw is thought to diminish, or die out completely, at lower latitudes, where glacial landscapes occupy only a small part of mountain belts affected by Pleistocene glaciation. Here we argue that glacial erosion has actually truncated the rise of many tropical orogens. To elicit signs of height-limiting glacial erosion in the tropics, we employ a new take on an old tool: we identify transient geomorphic features by tracking the evolution of (sub)catchment hypsometry with increasing elevation above base level, a method we term "progressive hypsometry." In several tropical mountain belts, including the Central Range of Taiwan, the Talamanca of Costa Rica, the Finisterres of Papua New Guinea, and the Rwenzoris of East Africa, progressive hypsometry reveals transient landscapes perched at various elevations, but the highest of these transient features are consistently glacial landscapes near the lower limit of late-Pleistocene glacial equilibrium line altitude (ELA) fluctuation. We attribute this pattern to an efficient glacial buzzsaw. In many cases, these glacial landscapes are undergoing contemporary destruction by headward propagating, fluvially-driven escarpments. We deduce that a duel between glacial buzzcutting and fluvially-driven scarp propagation has been ongoing throughout the Pleistocene in these places, and that the preservation potential of tropical glacial landscapes is low. To this end, we have identified possible remnants of glacial landscapes in the final stages of scarp consumption, and use 3He surface exposure age dating of boulders and bedrock surfaces in two of these landscapes to constrain major geomorphic activity to before the onset of the Last Glacial Maximum. Our work points to a profound climatic influence on the evolution of these warm, tectonically active

  20. An integrative water balance model framework for a changing glaciated catchment in the Andes of Peru

    Science.gov (United States)

    Drenkhan, Fabian; Huggel, Christian; García Hernández, Javier; Fluixá-Sanmartín, Javier; Seidel, Jochen; Muñoz Asmat, Randy

    2017-04-01

    In the Santa River catchment [SRC] (Cordillera Blanca, Andes of Peru), human livelihoods strongly depend on year-round streamflow from glaciers and reservoirs, particularly in the dry season and in adjacent arid lowlands. Perennial glacial streamflow represents a buffer to water shortages, annual discharge variability and river contamination levels. However, climate change impacts, consecutive glacier shrinkage as well as new irrigated agriculture and hydropower schemes, population growth and thus water allocation might increase water scarcity in several areas of the SRC. This situation exerts further pressure and conflict potential over water resources and stresses the need to analyze both water supply and demand trends in a multidisciplinary and interlinked manner. In this context, an integrative glacio-hydrological framework was developed based on the Glacier and Snow Melt (GSM) and SOil CONTribution (SOCONT) models using the semi-distributed free software RS MINERVE. This water balance model incorporates hydroclimatic, socioeconomic and hydraulic objects and data at daily scale (with several gaps) for the last 50 years (1965-2015). A particular challenge in this context represents the poor data availability both in quantity and quality. Therefore, the hydroclimatic dataset to be used had to be carefully selected and data gaps were filled applying a statistical copula-based approach. The socioeconomic dataset of water demand was elaborated using several assumptions based on further census information and experiences from other projects in the region. Reservoirs and hydropower models were linked with additional hydraulic data. In order to increase model performance within a complex topography of the 11660 km2 SRC, the area was divided into 22 glaciated (GSM) and 42 non-glaciated (SOCONT) subcatchment models. Additionally, 382 elevation bands at 300 m interval were created and grouped into 22 different calibration zones for the whole SRC. The model was calibrated

  1. Geochronology and Equilibrium Line Altitudes of LLGM through Holocene Glaciations from the Tropical Cordillera Huayhuash, Peru

    Science.gov (United States)

    Hall, S. R.; Ramage, J. M.; Rodbell, D. T.; Finkel, R. C.; Smith, J. A.; Mark, B. G.; Farber, D. L.

    2006-12-01

    Geomorphologic relationships and cosmogenic 10Be ages from the Central Peruvian Andes reveal a rich record of glaciations from at least the late Holocene, Late Glacial, Last Local Glacial Maximum (LLGM), and older more extensive glaciations - dated between 50ka and 440ka in both the Cordillera Blanca, to the north and the Junin Region to the south. The Cordillera Huayhuash (10.3°S, 76.9°W) is located between these two well-studied regions. The spine of the range trends nearly north-south and contains a substantial east-west spur which together can be used to evaluate the spatial variation in paleo-ELAs. The range is thus a key location to study changes in ice extent and equilibrium line altitudes (ELAs) between the LLGM and modern periods. Modern glaciers are confined to altitudes >4800 m and the present (1997) ELA is 4800- 5100m. In order to determine the paleo-ice positions of glaciers in different valleys we have developed a new chronology from cosmogenic 10Be ages of moraine boulder and 14C basal bog core ages. Through field mapping of glacial features, analysis of satellite imagery, digital elevation models (DEMs), and geochronology, we have delineated the ice limits associated with the LLGM, Late Glacial, and Late Holocene advances. Ages in the three valleys we have studied cluster at ~29ka, ~13ka, and ~9ka and overall we have identified surfaces with ages that range from 39.9±1.4ka to 0.2ka±0.05ka. Based on these data, we have mapped the extent of the correlative paleo-glaciers in these three drainages and extracted the modern hypsometry for each paleo-glacier from the DEMs. From this data set, we have generated paleo- ELAs using a range of methods: Toe-to-Headwall-Altitude Ratio (THAR), the Accumulation Area Ratio (AAR), and Accumulation Area Balance Ratio (AABR). For each of the LLGM, Late Glacial and Holocene stages, we have calculated both: (1) the temperature depression assuming no moisture variations, and (2) the potential relative moisture

  2. Sensor Webs and Virtual Globes: Enabling Understanding of Changes in a partially Glaciated Watershed

    Science.gov (United States)

    Heavner, M.; Fatland, D. R.; Habermann, M.; Berner, L.; Hood, E.; Connor, C.; Galbraith, J.; Knuth, E.; O'Brien, W.

    2008-12-01

    The University of Alaska Southeast is currently implementing a sensor web identified as the SouthEast Alaska MOnitoring Network for Science, Telecommunications, Education, and Research (SEAMONSTER). SEAMONSTER is operating in the partially glaciated Mendenhall and Lemon Creek Watersheds, in the Juneau area, on the margins of the Juneau Icefield. These watersheds are studied for both 1. long term monitoring of changes, and 2. detection and analysis of transient events (such as glacier lake outburst floods). The heterogeneous sensors (meteorologic, dual frequency GPS, water quality, lake level, etc), power and bandwidth constraints, and competing time scales of interest require autonomous reactivity of the sensor web. They also present challenges for operational management of the sensor web. The harsh conditions on the glaciers provide additional operating constraints. The tight integration of the sensor web and virtual global enabling technology enhance the project in multiple ways. We are utilizing virtual globe infrastructures to enhance both sensor web management and data access. SEAMONSTER utilizes virtual globes for education and public outreach, sensor web management, data dissemination, and enabling collaboration. Using a PosgreSQL with GIS extensions database coupled to the Open Geospatial Consortium (OGC) Geoserver, we generate near-real-time auto-updating geobrowser files of the data in multiple OGC standard formats (e.g KML, WCS). Additionally, embedding wiki pages in this database allows the development of a geospatially aware wiki describing the projects for better public outreach and education. In this presentation we will describe how we have implemented these technologies to date, the lessons learned, and our efforts towards greater OGC standard implementation. A major focus will be on demonstrating how geobrowsers and virtual globes have made this project possible.

  3. Mount Meager Volcano, Canada: a Case Study for Landslides on Glaciated Volcanoes

    Science.gov (United States)

    Roberti, G. L.; Ward, B. C.; van Wyk de Vries, B.; Falorni, G.; Perotti, L.; Clague, J. J.

    2015-12-01

    Mount Meager is a strato-volcano massif in the Northern Cascade Volcanic Arc (Canada) that erupted in 2350 BP, the most recent in Canada. To study the stability of the Massif an international research project between France ( Blaise Pascal University), Italy (University of Turin) and Canada (Simon Fraser University) and private companies (TRE - sensing the planet) has been created. A complex history of glacial loading and unloading, combined with weak, hydrothermally altered rocks has resulted in a long record of catastrophic landslides. The most recent, in 2010 is the third largest (50 x 106 m3) historical landslide in Canada. Mount Meager is a perfect natural laboratory for gravity and topographic processes such as landslide activity, permafrost and glacial dynamics, erosion, alteration and uplift on volcanoes. Research is aided by a rich archive of aerial photos of the Massif (1940s up to 2006): complete coverage approximately every 10 years. This data set has been processed and multi-temporal, high resolution Orthophoto and DSMs (Digital Surface Models) have been produced. On these digital products, with the support on field work, glacial retreat and landslide activity have been tracked and mapped. This has allowed for the inventory of unstable areas, the identification of lava flows and domes, and the general improvement on the geologic knowledge of the massif. InSAR data have been used to monitor the deformation of the pre-2010 failure slope. It will also be used to monitor other unstable slopes that potentially can evolve to catastrophic collapses of up to 1 km3 in volume, endangering local communities downstream the volcano. Mount Meager is definitively an exceptional site for studying the dynamics of a glaciated, uplifted volcano. The methodologies proposed can be applied to other volcanic areas with high erosion rates such as Alaska, Cascades, and the Andes.

  4. Onset and Multiple Fluctuations of Holocene Glaciation in the Sierra Nevada, California

    Science.gov (United States)

    Bowerman, N. D.; Clark, D. H.

    2004-12-01

    Multiple sediment cores from two paternoster tarns (First and Second lakes) in North Fork Big Pine Creek, Sierra Nevada, preserve the most detailed and complete record of Holocene glaciation yet recovered in the range; they indicate that the glacier was absent during the early Holocene, reformed in the late Holocene, and experienced several expansions and contractions, culminating with the Matthes maximum during the last ˜200 years. The lakes are fed by outwash from the Palisade Glacier, the largest ( ˜1.3 km2) and presumably longest-lived glacier in the Sierra Nevada, and capture essentially all of the rock flour produced by the glacier. Distinct late-Holocene (Matthes) and late-Pleistocene (Recess Peak) moraines lie between the modern glacier and the lakes. Thus, the lakes have received continuous sedimentation since the retreat of the Tioga glacier ( ˜15,000 yr B.P.), and therefore capture rock flour related to all subsequent advances. First and Second lakes occupy relatively deep bedrock basins at 3036 m and 3066 m asl., respectively. Third Lake, a shallow (rock flour (outwash) from the upstream Palisade Glacier, most likely related to formation and expansions of the glacier in the late Holocene. The maximum peak at the top of the cores confirms the moraine record, which indicates that the maximum Holocene advance of Sierran glaciers occurred during the late Little Ice Age (last ˜200 yr) At least one tephra layer, possibly related to the Mono/Inyo dome complexes, occurs in the middle depths of the First Lake cores. Other narrow peaks in MS may also be associated with tephra deposits. Ongoing detailed analyses of the sediments, including AMS radiocarbon dating, visual and x-ray imaging, particle size analysis, organic content, tephrochronology, diatom assemblages, and palynology will constrain the timing and character of the environmental fluctuations related to the rock-flour flux. We will present results of these analyses at the meeting.

  5. District element modelling of the rock mass response to glaciation at Finnsjoen, central Sweden

    International Nuclear Information System (INIS)

    Rosengren, L.; Stephansson, O.

    1990-12-01

    Six rock mechanics models of a cross section of the Finnsjoen test site have been simulated by means of distinct element analysis and the computer code UDEC. The rock mass response to glaciation, deglaciation, isostatic movements and water pressure from an ice lake have been simulated. Four of the models use a boundary condition with boundary elements at the bottom and sides of the model. This gives a state of stress inside the model which agrees well with the analytical solution where the horizontal and vertical stresses are almost similar. Roller boundaries were applied to two models. This boundary condition cause zero lateral displacement at the model boundaries and the horizontal stress are always less than the vertical stress. Isostatic movements were simulated in one model. Two different geometries of fracture Zone 2 were simulated. Results from modelling the two different geometries show minor changes in stresses, displacements and failure of fracture zones. Under normal pore pressure conditions in the rock mass the weight of the ice load increases the vertical stresses in the models differ depending on the boundary condition. An ice thickness of 3 km and 1 km and an ice wedge of 1 km thickness covering half the top surface of the model have been simulated. For each loading sequence of the six models a complete set of data about normal stress, stress profiles along selected sections, displacements and failure of fracture zones are presented. Based on the results of this study a protection zone of about 100 m width from the outer boundary of stress discontinuity to the repository location is suggested. This value is based on the result that the stress disturbance diminishes at this distance from the outer boundary of the discontinuity. (25 refs.) (authors)

  6. DOE's Yucca Mountain studies

    International Nuclear Information System (INIS)

    1992-12-01

    This booklet is about the disposal of high-level nuclear waste in the United States. It is for readers who have a general rather than a technical background. It discusses why scientists and engineers thinkhigh-level nuclear waste may be disposed of safely underground. It also describes why Yucca Mountain, Nevada, is being studied as a potential repository site and provides basic information about those studies

  7. Yucca Mountain Milestone

    International Nuclear Information System (INIS)

    Hunt, Rod

    1997-01-01

    The Department of Energy project to determine if the Yucca Mountain site in Nevada is suitable for geologic disposal of high-level nuclear waste reached a major milestone in late April when a 25-foot-diameter tunnel boring machine ''holed through'' completing a five-mile-long, horseshoe-shaped excavation through the mountain. When the cutting-head of the giant machine broke through to daylight at the tunnel's south portal, it ended a 2 1/2-year excavation through the mountain that was completed ahead of schedule and with an outstanding safety record. Video of the event was transmitted live by satellite to Washington, DC, where it was watched by Secretary of Energy Frederico Pena and other high-level DOE officials, signifying the importance of the project's mission to find a repository for high-level nuclear waste and spent nuclear fuel produced by nuclear power plants. This critical undertaking is being performed by DOE's Office of Civilian Radioactive Waste Management (OCRWM). The tunnel is the major feature of the Exploratory Studies Facility (ESF), which serves as an underground laboratory for engineers and scientists to help determine if Yucca Mountain is suitable to serve as a repository for the safe disposal of high-level nuclear waste. Morrison Knudsen's Environmental/Government Group is providing design and construction-management services on the project. The MK team is performing final design for the ESF and viability assessment design for the underground waste repository that will be built only if the site is found suitable for such a mission. In fact, if at anytime during the ESF phase, the site is found unsuitable, the studies will be stopped and the site restored to its natural state

  8. ACUTE MOUNTAIN SICKNESS

    Directory of Open Access Journals (Sweden)

    Jakub Krzeszowiak

    2012-03-01

    Full Text Available This paper presents the most likely pathophysiological causes of the development of acute mountain sickness (AMS, also known as altitude sickness, its pulmonary form i.e. high altitude pulmonary edema (HAPE, and high altitude cerebral edema (HACE. These diseases constitute extraordinary environmental hazards because they are directly connected with low atmospheric pressure, and thus low partial oxygen pressure. The above adverse atmospheric conditions start to affect humans already at an altitude of 2,500 meters above the sea level and, coupled with extreme physical exertion, can quickly lead to respiratory alkalosis, which is not present under any other conditions in the lowlands. Mountaineering above 4,500 m a.s.l. leads to hypoxia of internal organs and, primarily, reduced renal perfusion with all its consequences. The above adverse changes, combined with inadequate acclimatization, can lead to a situation of imminent danger to life and health. This paper describes in detail the consequences of acute mountain sickness, which can ultimately lead to the development of AMS and one of severe forms of HACE and/or HAPE.

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

    Science.gov (United States)

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

    2018-03-01

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

  10. Water Resources and Groundwater in a Glaciated Andean Watershed (Cordillera Blanca, Peru)

    Science.gov (United States)

    McKenzie, J. M.; Gordon, R.; Baraer, M.; Lautz, L.; Mark, B. G.; Wigmore, O.; Chavez, D.; Aubry-Wake, C.

    2014-12-01

    It is estimated that almost 400 million people live in watersheds where glaciers provide at least 10% of the runoff, yet many questions remain regarding the impact of climate change and glacier recession on water resources derived from these high mountain watersheds. We present research from the Cordillera Blanca, Peru, an area with the highest density of glaciers in the tropics. While glacier meltwater buffers stream discharge throughout the range, groundwater is a major component of dry season runoff, contributing up to 50-70% of outflow in some tributaries. In order to predict future changes to water resources it is critical to understand how groundwater can offset future hydrologic stress by maintaining stream baseflow, including recharge mechanisms, subsurface pathways, storage, and net fluxes to rivers. We present a synthesis of results based on hydrologic modeling, drilling/piezometers, geophysics, and artificial and natural hydrologic tracers. Our findings show that 'pampas', low-relief mountain valleys, are critical for baseflow generation by storing groundwater on interannual timescales. Pampas have a total area of ~65 km2 and are comprised of unconsolidated glacial, talus, lacustrine and wetland (bofedales) deposits. The valleys commonly have buried talus aquifers that are overlain by low permeability, glaciolacustrine deposits. Glaciofluvial outwash deposits and small wetlands also act as unconfined aquifers. These groundwater systems appear to be primarily recharged by wet season precipitation, and at higher elevations also by glacial meltwater. Additionally a ubiquitous feature in the valleys are springs, often located at the base of talus deposits, which generate a large hydrologic flux within the hydrologic systems. While glaciers are the most visible and vulnerable component of the Andean waterscape, we argue that it is crucial to understand the complete mountain hydrologic cycle, including groundwater, in order to understand the ongoing

  11. Extremely low long-term erosion rates around the Gamburtsev Mountains in interior East Antarctica

    Science.gov (United States)

    Cox, S. E.; Thomson, S. N.; Reiners, P. W.; Hemming, S. R.; van de Flierdt, T.

    2010-11-01

    The high elevation and rugged relief (>3 km) of the Gamburtsev Subglacial Mountains (GSM) have long been considered enigmatic. Orogenesis normally occurs near plate boundaries, not cratonic interiors, and large-scale tectonic activity last occurred in East Antarctica during the Pan-African (480-600 Ma). We sampled detrital apatite from Eocene sands in Prydz Bay at the terminus of the Lambert Graben, which drained a large pre-glacial basin including the northern Gamburtsev Mountains. Apatite fission-track and (U-Th)/He cooling ages constrain bedrock erosion rates throughout the catchment. We double-dated apatites to resolve individual cooling histories. Erosion was very slow, averaging 0.01-0.02 km/Myr for >250 Myr, supporting the preservation of high elevation in interior East Antarctica since at least the cessation of Permian rifting. Long-term topographic preservation lends credence to postulated high-elevation mountain ice caps in East Antarctica since at least the Cretaceous and to the idea that cold-based glaciation can preserve tectonically inactive topography.

  12. Carboniferous rifted arcs leading to an archipelago of multiple arcs in the Beishan-Tianshan orogenic collages (NW China)

    Science.gov (United States)

    Tian, Zhonghua; Xiao, Wenjiao; Windley, Brian F.; Zhang, Ji'en; Zhang, Zhiyong; Song, Dongfang

    2017-10-01

    The Beishan and East Tianshan Orogenic Collages in the southernmost Central Asian Orogenic Belt (CAOB) record the final stages of evolution of the Paleo-Asian Ocean. These collages and their constituent arcs have an important significance for resolving current controversies regarding their tectonic setting and age, consequent accretionary history of the southern CAOB, and the closure time of the Paleo-Asian Ocean. In this paper, we present our work on the southern Mazongshan arc and the northern Hongyanjing Basin in the Beishan Orogenic Collage (BOC), and our comparison with the Bogda arc and associated basins in the East Tianshan Orogenic Collage. Field relationships indicate that the Pochengshan fault defines the boundary between the arc and basin in the BOC. Volcanic rocks including basalts and rhyolites in the Mazongshan arc have bimodal calc-alkaline characteristics, an enrichment in large ion lithophile elements such as Rb, Ba, and Pb and depletion in high field-strength elements (e.g., Nb and Ta), which were probably developed in a subduction-related tectonic setting. We suggest that these bimodal calc-alkaline volcanic rocks formed in rifted arcs instead of post-orogenic rifts with mantle plume inputs. By making detailed geochemical comparisons between the Mazongshan arc and the Bogda arc to the west, we further propose that they are similar and both formed in arc rifts, and helped generate a Carboniferous archipelago of multiple arcs in the southern Paleo-Asian Ocean. These data and ideas enable us to postulate a new model for the tectonic evolution of the southern CAOB.

  13. Sedimentological analysis and bed thickness statistics from a Carboniferous deep-water channel-levee complex: Myall Trough, SE Australia

    Science.gov (United States)

    Palozzi, Jason; Pantopoulos, George; Maravelis, Angelos G.; Nordsvan, Adam; Zelilidis, Avraam

    2018-02-01

    This investigation presents an outcrop-based integrated study of internal division analysis and statistical treatment of turbidite bed thickness applied to a Carboniferous deep-water channel-levee complex in the Myall Trough, southeast Australia. Turbidite beds of the studied succession are characterized by a range of sedimentary structures grouped into two main associations, a thick-bedded and a thin-bedded one, that reflect channel-fill and overbank/levee deposits, respectively. Three vertically stacked channel-levee cycles have been identified. Results of statistical analysis of bed thickness, grain-size and internal division patterns applied on the studied channel-levee succession, indicate that turbidite bed thickness data seem to be well characterized by a bimodal lognormal distribution, which is possibly reflecting the difference between deposition from lower-density flows (in a levee/overbank setting) and very high-density flows (in a channel fill setting). Power law and exponential distributions were observed to hold only for the thick-bedded parts of the succession and cannot characterize the whole bed thickness range of the studied sediments. The succession also exhibits non-random clustering of bed thickness and grain-size measurements. The studied sediments are also characterized by the presence of statistically detected fining-upward sandstone packets. A novel quantitative approach (change-point analysis) is proposed for the detection of those packets. Markov permutation statistics also revealed the existence of order in the alternation of internal divisions in the succession expressed by an optimal internal division cycle reflecting two main types of gravity flow events deposited within both thick-bedded conglomeratic and thin-bedded sandstone associations. The analytical methods presented in this study can be used as additional tools for quantitative analysis and recognition of depositional environments in hydrocarbon-bearing research of ancient

  14. Geochemistry and tectonic implications of the Early Carboniferous Keketuobie intrusion in the West Junggar foldbelt, NW China

    Science.gov (United States)

    Deng, Yu-Feng; Yuan, Feng; Zhou, Taofa; Hollings, Pete; Zhang, Dayu

    2018-06-01

    The Keketuobie intrusion is situated in the northern part of the West Junggar foldbelt at the southern margin of the Central Asian Orogeic Belt. The intrusion consists of medium- to coarse-grained gabbro, fine-grained gabbro and diorite. Igneous zircons from the medium- to coarse-grained gabbro yielded a LA-ICP-MS U-Pb age of 320.8 ± 5.7 Ma, indicating that the intrusion was emplaced in the Early Carboniferous. The intrusive contact between the medium- to coarse-grained gabbro and the fine-grained gabbro indicates they formed from distinct magma pulses. Magnetite crystals from the fine-grained gabbro have lower V2O3 but higher TiO2 and Al2O3 contents than those of the medium- to coarse-grained gabbro, suggesting that the fine-grained gabbro crystallized in a relatively higher fO2 and temperature magma than the medium- to coarse-grained gabbro. The Keketuobie intrusive rocks are characterized by enriched large ion lithophile elements and depleted high field strength elements relative to N-MORB with restricted (87Sr/86Sr)t ratios (0.70370-0.70400) and εNd(t) values (+5.85 to +6.97). The petrography and geochemistry are comparable to those of subduction-related volcanic rocks. The trace elements and isotopic compositions of the mafic intrusive rocks suggest that the primary magmas were derived from mixing of metasomatized lithospheric mantle and depleted asthenospheric melts, perhaps triggered by slab break-off. The Keketuobie intrusion is younger than adjacent ophiolite sequences, island arc volcanic rocks and porphyry deposits, but predates the post-collisional A-type granites and bimodal volcanic rocks in the district, suggesting that the Keketuobie intrusion likely formed in a syn-collisional setting.

  15. A new paleozoic Symmoriiformes (Chondrichthyes from the late Carboniferous of Kansas (USA and cladistic analysis of early chondrichthyans.

    Directory of Open Access Journals (Sweden)

    Alan Pradel

    Full Text Available BACKGROUND: The relationships of cartilaginous fishes are discussed in the light of well preserved three-dimensional Paleozoic specimens. There is no consensus to date on the interrelationship of Paleozoic chondrichthyans, although three main phylogenetic hypotheses exist in the current literature: 1. the Paleozoic shark-like chondrichthyans, such as the Symmoriiformes, are grouped along with the modern sharks (neoselachians into a clade which is sister group of holocephalans; 2. the Symmoriiformes are related to holocephalans, whereas the other Paleozoic shark-like chondrichthyans are related to neoselachians; 3. many Paleozoic shark-like chondrichthyans, such as the Symmoriiformes, are stem chondrichthyans, whereas stem and crown holocephalans are sister group to the stem and crown neoselachians in a crown-chondrichthyan clade. This third hypothesis was proposed recently, based mainly on dental characters. METHODOLOGY/PRINCIPAL FINDINGS: On the basis of two well preserved chondrichthyan neurocrania from the Late Carboniferous of Kansas, USA, we describe here a new species of Symmoriiformes, Kawichthys moodiei gen. et sp. nov., which was investigated by means of computerized X-ray synchrotron microtomography. We present a new phylogenetic analysis based on neurocranial characters, which supports the third hypothesis and corroborates the hypothesis that crown-group chondrichthyans (Holocephali+Neoselachii form a tightly-knit group within the chondrichthyan total group, by providing additional, non dental characters. CONCLUSIONS/SIGNIFICANCE: Our results highlight the importance of new well preserved Paleozoic fossils and new techniques of observation, and suggest that a new look at the synapomorphies of the crown-group chondrichthyans would be worthwhile in terms of understanding the adaptive significance of phylogenetically important characters.

  16. Testing new methodologies and assessing their potential for reservoir characterisation: Geoelectrical studies in the Northwest Carboniferous Basin (Ireland).

    Science.gov (United States)

    Ogaya, Xènia; Campanyà, Joan; Rath, Volker; Jones, Alan G.; Reay, Derek; Raine, Rob; McConnell, Brian; Ledo, Juanjo

    2016-04-01

    The overarching objective of this study is to improve our methods of characterising saline aquifers by integrating newly acquired electromagnetic data with existing geophysical and geological data. The work presented here is part of an ongoing project to evaluate Ireland's potential for onshore carbon sequestration (IRECCSEM; funded by Science Foundation Ireland). The methodology presented in this characterisation work is not only relevant for studying the potential for onshore carbon sequestration, but is generally applicable for aquifer characterisation, particularly for the evaluation of geothermal resources in appropriate geological settings. We present first results of the three-dimensional (3D) modelling and inversion of the magnetotelluric (MT) data acquired in the Northwest Carboniferous Basin (Ireland) in summer 2015. The electrical resistivity distribution beneath the survey area is constrained using a joint inversion of three different types of electromagnetic data: MT impedance tensor responses (Z), geomagnetic transfer functions (GTF) and inter-station horizontal magnetic transfer-functions (HMT). The preliminary 3D resistivity model obtained reveals the geoelectrical structure of the subsurface, which is translated into parameters relevant to fluid flow. The electromagnetic data were acquired along profiles linking four wells drilled in the area and the available well log data from those wells are used to evaluate some of the existing petrophysical relationships and calibrate them for the study area. This allows us to interpolate the rock physical properties from one well to another well, using the computed geoelectrical model as a reference. The obtained results are compared to available independent geological and geophysical data in order to analyse the validity of this technique, to characterise the uncertainties inherent to our approach, and to assess the potential of this methodology for reservoir characterisation.

  17. Genesis of Pb-Zn-Cu-Ag Deposits within Permian Carboniferous-Carbonate Rocks in Madina Regency, North Sumatra

    Directory of Open Access Journals (Sweden)

    Bhakti Hamonangan Harahap

    2015-09-01

    Full Text Available DOI:10.17014/ijog.2.3.167-184Strong mineralized carbonate rock-bearing Pb-Zn-Cu-Ag-(Au ores are well exposed on the Latong River area, Madina Regency, North Sumatra Province. The ore deposit is hosted within the carbonate rocks of the Permian to Carboniferous Tapanuli Group. It is mainly accumulated in hollows replacing limestone in the forms of lensoidal, colloform, veins, veinlets, cavity filling, breccia, and dissemination. The ores dominantly consist of galena (126 000 ppm Pb and sphalerite (2347 ppm Zn. The other minerals are silver, azurite, covellite, pyrite, marcasite, and chalcopyrite. This deposit was formed by at least three phases of mineralization, i.e. pyrite and then galena replaced pyrite, sphalerite replaced galena, and pyrite. The last phase is the deposition of chalcopyrite that replaced sphalerite. The Latong sulfide ore deposits posses Pb isotope ratio of 206Pb/204Pb = 19.16 - 20.72, 207Pb/204Pb = 16.16 - 17.29, and 208Pb/204Pb = 42.92 - 40.78. The characteristic feature of the deposit indicates that it is formed by a sedimentary process rather than an igneous activity in origin. This leads to an interpretation that the Latong deposit belongs to the Sedimentary Hosted Massive Sulfide (SHMS of Mississippi Valley-Type (MVT. The presence of SHMS in the island arc such as Sumatra has become controversial. For a long time, ore deposits in the Indonesian Island Arc are always identical with the porphyry and hydrothermal processes related to arc magmatism. This paper is dealing with the geology of Latong and its base metal deposits. This work is also to interpret their genesis as well as general relationship to the regional geology and tectonic setting of Sumatra.

  18. Continental glaciation and its potential impact on a used-fuel disposal vault in the Canadian Shield

    International Nuclear Information System (INIS)

    Ates, Y.; Bruneau, D.; Ridgway, W.R.

    1997-09-01

    AECL has been assessing the concept of nuclear fuel waste disposal in a vault excavated at a depth ranging between 500 m and 1000 m in a plutonic rock mass of the Canadian Shield. Glaciation is a natural process that has occurred in the past, and is likely to occur in the future, thus causing changes in the loading conditions on the rock mass hosting the disposal vault. Because the rock mass is a natural barrier to the migration of radionuclides, it is important to evaluate its integrity under load changes caused by the glaciation process. Assuming that the magnitude and extent of the future glaciation will be similar to those of the past, we have reviewed published data pertaining to the last continental ice sheet that covered a large area of North America. Estimates have been made for the magnitude of stresses due to ice sheet loading for a vault located at depths of 500 to 1000 m. These analyses have shown that the uniform loading of a continental ice sheet would reduce the deviatoric stresses in the Canadian Shield, creating more favourable conditions than those existing at the present time, namely, high horizontal stresses. The effects of surface erosion and increase in the in-situ shear stresses have also been examined. Based on the existing data and structural modelling studies, there would be no significant structural effect on a disposal vault located at 1000-m depth in a plutonic rock. At its maximum size, an ice sheet comparable to the Laurentide ice sheet could reactivate the faults and fracture zones along the perimeter areas. Our analyses have been based on fully drained conditions only. At a potential disposal site, it would be important also to consider the potential for excess pore pressure in the analyses. (author)

  19. Continental glaciation and its potential impact on a used-fuel disposal vault in the Canadian Shield

    Energy Technology Data Exchange (ETDEWEB)

    Ates, Y.; Bruneau, D.; Ridgway, W.R

    1997-09-01

    AECL has been assessing the concept of nuclear fuel waste disposal in a vault excavated at a depth ranging between 500 m and 1000 m in a plutonic rock mass of the Canadian Shield. Glaciation is a natural process that has occurred in the past, and is likely to occur in the future, thus causing changes in the loading conditions on the rock mass hosting the disposal vault. Because the rock mass is a natural barrier to the migration of radionuclides, it is important to evaluate its integrity under load changes caused by the glaciation process. Assuming that the magnitude and extent of the future glaciation will be similar to those of the past, we have reviewed published data pertaining to the last continental ice sheet that covered a large area of North America. Estimates have been madefor the magnitude of stresses due to ice sheet loading for a vault located at depths of 500 to 1000 m. These analyses have shown that the uniform loading of a continental ice sheet would reduce the deviatoric stresses in the Canadian Shield, creating more favourable conditions than those existing at the present time, namely, high horizontal stresses. The effects of surface erosion and increase in the in-situ shear stresses have also been examined. Based on the existing data and structural modelling studies, there would be no significant structural effect on a disposal vault located at 1000-m depth in a plutonic rock. At its maximum size, an ice sheet comparable to the Laurentide ice sheet could reactivate the faults and fracture zones along the perimeter areas. Our analyses have been based on fully drained conditions only. At a potential disposal site, it would be important also to consider the potential for excess pore pressure in the analyses. (author)

  20. Glaciation style and the geomorphological record: evidence for Younger Dryas glaciers in the eastern Lake District, northwest England

    Science.gov (United States)

    McDougall, Derek

    2013-08-01

    The Younger Dryas (c. 12,900-11,700 years ago) in Britain witnessed renewed glaciation, with the readvance of ice masses that had survived the preceding Lateglacial Interstadial as well as the formation of new glaciers. The extents of these former glaciers have been mapped by many workers over the past fifty years, usually as a basis for palaeoclimatic investigations. It has frequently been asserted that the landform record is sufficiently clear to allow accurate ice mass reconstructions at or near maximum extents. Detailed geomorphological mapping in the eastern Lake District in NW England, however, demonstrates that this confidence may not always be warranted. Whereas previous workers have interpreted the well-developed moraines that exist in some locations as evidence for an alpine-style of glaciation, with ice restricted to a small number of valleys, this study shows that the most recent glaciation to affect the area was characterised by: (i) extensive summit icefields, which supplied ice to the surrounding valleys; and (ii) a much greater volume of ice in the valleys than previously thought. The discovery that summit icefields were relatively common at this time is consistent with recent studies elsewhere in the Lake District and beyond. More significant, however, is the recognition that changing glacier-topographic interactions over both space and time appears to have had a profound impact on valley-floor glacial landform development, with the absence of clear moraines not necessarily indicating ice-free conditions at this time. This complicates glacier reconstructions based solely on the geomorphological record. Similar geomorphological complexity may be present in other areas that previously supported summit icefields, and this needs to be taken into account in glacier reconstructions.

  1. Mantle contribution and tectonic transition in the Aqishan-Yamansu Belt, Eastern Tianshan, NW China: Insights from geochronology and geochemistry of Early Carboniferous to Early Permian felsic intrusions

    Science.gov (United States)

    Du, Long; Long, Xiaoping; Yuan, Chao; Zhang, Yunying; Huang, Zongying; Wang, Xinyu; Yang, Yueheng

    2018-04-01

    Late Paleozoic is a key period for the accretion and collision of the southern Central Asian Orogenic Belt (CAOB). Here, we present new zircon U-Pb ages, whole-rock geochemistry and Sr-Nd isotopic compositions for four Late Paleozoic felsic plutons in Eastern Tianshan (or Tienshan in some literatures) in order to constrain the tectonic evolution of the southern CAOB. The granodioritic pluton and its dioritic enclaves were synchronously formed in the Early Carboniferous (336 ± 3 Ma and 335 ± 2 Ma, respectively). These rocks are depleted in Nb, Ta and Ti, and enriched in Rb, Ba, Th and U related to the primitive mantle, which show typical features of arc rocks. They both have similar Sr-Nd isotopic ratios to those granitic rocks from the eastern Central Tianshan Block and have the latest Mesoproterozoic two stage Nd model ages (TDM2) (1111-1195 Ma for the granodioritic pluton and 1104-1108 Ma for the enclaves, respectively), indicating that their source magmas may have been derived from the Mesoproterozoic crust. The albitophyric pluton was also emplaced in the Early Carboniferous (333 ± 3 Ma). Rocks of this pluton have similar εNd(t) values (-0.69 to -0.37) and TDM2 ages (1135-1161 Ma) to those of the granodioritic rocks, suggest similar crustal source for both types of rocks. In contrast, the K-feldspar granitic and monzonitic plutons were emplaced in the Early Permian (292 ± 3 Ma and 281 ± 2 Ma, respectively). Samples of the K-feldspar granitic pluton have high K2O + Na2O, FeO/MgO, Ga/Al, HFSE (e.g., Zr and Hf) and low CaO, Sr and Ba, exhibiting characteristics of A2-type granites, which probably emplaced in a post-collisional extension environment. They have higher εNd(t) values (+2.77 to +3.27) and more juvenile TDM2 ages (799-841 Ma) than the Early Carboniferous plutons, suggesting that they were derived from relatively younger crustal sources. The monzonitic granites are metaluminous to weakly peraluminous with A/CNK ranging from 0.93 to 1.05, and have

  2. Quantifying Heterogeneities in Soil Cover and Weathering in the Bitterroot and Sapphire Mountains, Montana: Implications for Glacial Legacies and their Morphologic Control on Soil Formation

    Science.gov (United States)

    Benjaram, S. S.; Dixon, J. L.

    2017-12-01

    To what extent is chemical weathering governed by a landscape's topography? Quantifying chemical weathering in both steep rocky landscapes and soil-mantled landscapes requires describing heterogeneity in soil and rock cover at local and landscape scales. Two neighboring mountain ranges in the northern Rockies of western Montana, USA, provide an ideal natural laboratory in which to investigate the relationship between soil chemical weathering, persistence of soil cover, and topography. We focus our work in the previously glaciated Bitterroot Mountains, which consist of steep, rock-dominated hillslopes, and the neighboring unglaciated Sapphire Mountains, which display convex, soil-mantled hillslopes. Soil thickness measurements, soil and rock geochemistry, and digital terrain analysis reveal that soils in the rock-dominated Bitterroot Mountains are only slightly less weathered than those in the Sapphire Mountains. However, these differences are magnified when adjusted for rock fragments at a local scale and bedrock cover at a landscape scale, using our newly developed metric, the rock-adjusted chemical depletion fraction (RACDF) and rock-adjusted mass transfer coefficient (RA τ). The Bitterroots overall are 30% less weathered than the Sapphires despite higher mean annual precipitation in the former, with an average rock-adjusted CDF of 0.38 in the postglacial Bitterroots catchment and 0.61 in the nonglacial Sapphire catchment, suggesting that 38% of rock mass is lost in the conversion to soil in the Bitterroots, whereas 61% of rock mass is lost in the nonglaciated Sapphires. Because the previously glaciated Bitterroots are less weathered despite being wetter, we conclude that the glacial history of this landscape exerts more influence on soil chemical weathering than does modern climate. However, while previous studies have correlated weathering intensity with topographic parameters such as slope gradient, we find little topographic indication of specific controls

  3. ICESat laser altimetry over small mountain glaciers

    Directory of Open Access Journals (Sweden)

    D. Treichler

    2016-09-01

    Full Text Available Using sparsely glaciated southern Norway as a case study, we assess the potential and limitations of ICESat laser altimetry for analysing regional glacier elevation change in rough mountain terrain. Differences between ICESat GLAS elevations and reference elevation data are plotted over time to derive a glacier surface elevation trend for the ICESat acquisition period 2003–2008. We find spatially varying biases between ICESat and three tested digital elevation models (DEMs: the Norwegian national DEM, SRTM DEM, and a high-resolution lidar DEM. For regional glacier elevation change, the spatial inconsistency of reference DEMs – a result of spatio-temporal merging – has the potential to significantly affect or dilute trends. Elevation uncertainties of all three tested DEMs exceed ICESat elevation uncertainty by an order of magnitude, and are thus limiting the accuracy of the method, rather than ICESat uncertainty. ICESat matches glacier size distribution of the study area well and measures small ice patches not commonly monitored in situ. The sample is large enough for spatial and thematic subsetting. Vertical offsets to ICESat elevations vary for different glaciers in southern Norway due to spatially inconsistent reference DEM age. We introduce a per-glacier correction that removes these spatially varying offsets, and considerably increases trend significance. Only after application of this correction do individual campaigns fit observed in situ glacier mass balance. Our correction also has the potential to improve glacier trend significance for other causes of spatially varying vertical offsets, for instance due to radar penetration into ice and snow for the SRTM DEM or as a consequence of mosaicking and merging that is common for national or global DEMs. After correction of reference elevation bias, we find that ICESat provides a robust and realistic estimate of a moderately negative glacier mass balance of around −0.36 ± 0.07

  4. Application of surface-geophysical methods to investigations of sand and gravel aquifers in the glaciated Northeastern United States

    Science.gov (United States)

    Haeni, F.P.

    1995-01-01

    Combined use of seismic-refraction, direct-current resistivity, very-low-frequency terrain-resistivity, and inductive terrain-conductivity methods were demonstrated at sites in Connecticut, New York, and Maine. Although no single method can define both the hydrogeologic boundaries and general grain-size characteristics of sand and gravel aquifers, a combination of these methods can. Comparisons of measured electrical properties of aquifers with logs of test holes and wells indicate that, for a given conductivity of ground water, the bulk electrical resistivity of aquifers in the glaciated Northeast increases with grain size.

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

    Directory of Open Access Journals (Sweden)

    Grant M. Young

    2013-05-01

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

  6. Holocene depositional history of a large glaciated estuary, Penobscot Bay, Maine

    Science.gov (United States)

    Knebel, H.J.

    1986-01-01

    Data from seismic-reflection profiles, sidescan sonar images, and sediment samples reveal the Holocene depositional history of the large (1100 km2) glaciated Penobscot Bay estuary of coastal Maine. Previous work has shown that the late Wisconsinan ice sheet retreated from the three main passages of the bay between 12,700 and 13,500 years ago and was accompanied by a marine transgression during which ice and sea were in contact. Isostatic recovery of the crust caused the bay to emerge during the immediate postglacial period, and relative sea level fell to at least -40 m sometime between 9000 and 11,500 years ago. During lowered sea level, the ancestral Penobscot River flowed across the subaerially exposed head of the bay and debouched into Middle Passage. Organic-matter-rich mud from the river was deposited rapidly in remnant, glacially scoured depressions in the lower reaches of Middle and West Passages behind a shallow (???20 m water depth) bedrock sill across the bay mouth. East Passage was isolated from the rest of the bay system and received only small amounts of locally derived fine-grained sediments. During the Holocene transgression that accompanied the eustatic rise of sea level, the locus of sedimentation shifted to the head of the bay. Here, heterogeneous fluvial deposits filled the ancestral valley of the Penobscot River as base level rose, and the migrating surf zone created a gently dipping erosional unconformity, marked by a thin (energy conditions and the waning influence of the Penobscot River at the head of the bay. In contrast, relatively thick (up to 25 m) silty clays accumulated within a subbottom trough in the western half of the bay head. This deposit apparently developed late in the transgression after sea level had reached -20 m and after the westward transport of fine-grained sediments from the Penobscot River had been established. During and since the late Holocene transgression of sea level, waves and currents have eroded, reworked, and

  7. Groundwater-supported evapotranspiration within glaciated watersheds under conditions of climate change

    Science.gov (United States)

    Cohen, D.; Person, M.; Daannen, R.; Locke, S.; Dahlstrom, D.; Zabielski, V.; Winter, T.C.; Rosenberry, D.O.; Wright, H.; Ito, E.; Nieber, J.L.; Gutowski, W.J.

    2006-01-01

    This paper analyzes the effects of geology and geomorphology on surface-water/-groundwater interactions, evapotranspiration, and recharge under conditions of long-term climatic change. Our analysis uses hydrologic data from the glaciated Crow Wing watershed in central Minnesota, USA, combined with a hydrologic model of transient coupled unsaturated/saturated flow (HYDRAT2D). Analysis of historical water-table (1970-1993) and lake-level (1924-2002) records indicates that larger amplitude and longer period fluctuations occur within the upland portions of watersheds due to the response of the aquifer system to relatively short-term climatic fluctuations. Under drought conditions, lake and water-table levels fell by as much as 2-4 m in the uplands but by 1 m in the lowlands. The same pattern can be seen on millennial time scales. Analysis of Holocene lake-core records indicates that Moody Lake, located near the outlet of the Crow Wing watershed, fell by as much as 4 m between about 4400 and 7000 yr BP. During the same time, water levels in Lake Mina, located near the upland watershed divide, fell by about 15 m. Reconstructed Holocene climate as represented by HYDRAT2D gives somewhat larger drops (6 and 24 m for Moody Lake and Lake Mina, respectively). The discrepancy is probably due to the effect of three-dimensional flow. A sensitivity analysis was also carried out to study how aquifer hydraulic conductivity and land-surface topography can influence water-table fluctuations, wetlands formation, and evapotranspiration. The models were run by recycling a wet year (1985, 87 cm annual precipitation) over a 10-year period followed by 20 years of drier and warmer climate (1976, 38 cm precipitation). Model results indicated that groundwater-supported evapotranspiration accounted for as much as 12% (10 cm) of evapotranspiration. The aquifers of highest hydraulic conductivity had the least amount of groundwater-supported evapotranspiration owing to a deep water table. Recharge

  8. A mountain river sediment cascade and its controls: the Schöttlbach torrent, Styria

    Science.gov (United States)

    Lutzmann, Silke; Stangl, Johannes; Sass, Oliver

    2017-04-01

    Steep alpine headwater torrents are characterized by episodic heavy floods and bedload pulses triggered by local high-intensity mountain rainstorms. They frequently pose serious risks and damage in the densely populated East Alpine Region. It is important to understand where critical sediments are mobilized, how much bedload is delivered to the outlet and what controls the variability. We present a concept to quantify the sediment cascade's components and influencing factors for the Schöttlbach torrent - a 71 km2 non-glaciated catchment in the Niedere Tauern mountain Range in Styria, Austria. Geomorphic mapping is used to identify primary bedload sources on slope as well as patterns of lithology, slope-channel coupling and vegetation conditioning erosion intensity. We apply modern near-range measuring techniques (TLS, Structure from Motion) to monitor erosion rates from representative erosion sites and sediment delivery rates at the outlet since 2014. These measurements are interpreted based on the geomorphic map to derive a catchment-wide seasonal sediment budget. To explain seasonal variations we evaluate precipitation and discharge data from a dense station network as storm precipitation and runoff events are the main triggers of torrent sediment mobilization. Torrent reaches in instable glaciofluvial sediments of the last glaciation show high average erosion rates of ca. 0.08 m/a from 2014 to 2016 surpassing rates in deeply weathered bedrock reaches by an order of magnitude (approx. 0.006 m/a). We model a torrent-wide erosion volume of 2000 m3/a opposing an output of 7000 m3/a in that period. We attribute parts of this discrepancy to a sediment wave reworking signal of an extreme flood event in 2011.

  9. "Christ is the Mountain"

    Directory of Open Access Journals (Sweden)

    Carl Hallencreutz

    1979-01-01

    Full Text Available In this paper the author focuses on the religious function of symbols in the encounter and interaction of Christianity and other religions. Some observations on the religious function of the symbol of the Holy Mountain in different African contexts are presented. These contexts are a traditional Kikuyu religion, b a Christian hymn from Northern Tanzania, and c the New Year's Fiest of the independent Nazaretha Church among Zulu in South Africa. The examples of how the symbol of the holy mountain is used in different religious contexts in Africa are, of course, too limited to provide a basis for far-reaching generalizations on how symbols function religiously in the encounter of Christianity and other religions. However, this kind of analysis can be applied also when studying other encounters of religions inside and outside Africa. The symbol functions both as a carrier of a new religious message and as an indigenous means to appropriate this message locally and give it adequate form in different milieus. The symbols, which most likely have the religious functions are those which are of a general nature; light, way, living water, and which some are tempted to speak of as archetypes. Yet the comparison between the Chagga-hymn to the holy mountain and Shembe's interpretation of the blessing of the New Year's Fiest on Inhlangakozi indicates, that in the encounter of Christianity and other religions it is not only the symbols as such which produce the local appropriation of the new religious message and give it adequate localized form. Not even in the encounter of Christianity and other religions the symbols function religiously without human beings as actors in the historical process.

  10. Late Carboniferous to early Permian sedimentary–tectonic evolution of the north of Alxa, Inner Mongolia, China: Evidence from the Amushan Formation

    Directory of Open Access Journals (Sweden)

    Haiquan Yin

    2016-09-01

    Full Text Available The late Paleozoic evolution of the Wulijishanhen (WSH-Shangdan (SD area near to the Chaganchulu Ophiolite belt is reinterpreted. Analysis of the upper Carboniferous to lower Permian sedimentary sequence, biological associations, detrital materials, sandstone geochemistry and volcanic rocks indicates that the SD area was an epicontinental sea and rift during the late Paleozoic rather than a large-scale ocean undergoing spreading and closure. This study reveals that the actual evolution of the study area is from the late Carboniferous to the early Permian. The fusulinids Triticites sp. and Pseudoschwagerina sp. in the limestones demonstrate that the Amushan Formation develops during the late Carboniferous to the early Permian. The limestones at the base of the SD section indicate that it is a stable carbonate platform environment, the volcanic rocks in the middle of the sequence support a rift tectonic background, and the overlying conglomerates and sandstones are characteristic of an epicontinental sea or marine molasse setting. The rift volcanism made the differences in the fossil content of the SD and WSH sections and led to two sections expose different levels within the Amushan Formation and different process of tectonic evolution. Moreover, the geochemical characteristics and detrital materials of the sandstones show that the provenance and formation of the sandstones were related to the setting of active continental margin. The quartz-feldspar-lithic fragments distribution diagram indicates that the material source for the sandstones was a recycled orogenic belt. Thus, the source area of the sandstones may have been an active continental margin before the late Carboniferous–early Permian. The characteristics of the regional tectonic evolution of the area indicate that the region may form a small part of the Gobi–Tianshan rift of southern Mongolia.

  11. Carboniferous and Permian evolutionary records for the Paleo-Tethys Ocean constrained by newly discovered Xiangtaohu ophiolites from central Qiangtang, central Tibet

    Science.gov (United States)

    Zhang, Xiu-Zheng; Dong, Yong-Sheng; Wang, Qiang; Dan, Wei; Zhang, Chunfu; Deng, Ming-Rong; Xu, Wang; Xia, Xiao-Ping; Zeng, Ji-Peng; Liang, He

    2016-07-01

    Reconstructing the evolutionary history of the Paleo-Tethys Ocean remains at the center of debates over the linkage between Gondwana dispersion and Asian accretion. Identifying the remnants of oceanic lithosphere (ophiolites) has very important implications for identifying suture zones, unveiling the evolutionary history of fossil oceans, and reconstructing the amalgamation history between different blocks. Here we report newly documented ophiolite suites from the Longmu Co-Shuanghu Suture zone (LSSZ) in the Xiangtaohu area, central Qiangtang block, Tibet. Detailed geological investigations and zircon U-Pb dating reveal that the Xiangtaohu ophiolites are composed of a suite of Permian (281-275 Ma) ophiolites with a nearly complete Penrose sequence and a suite of Early Carboniferous (circa 350 Ma) ophiolite remnants containing only part of the lower oceanic crust. Geochemical and Sr-Nd-O isotopic data show that the Permian and Carboniferous ophiolites in this study were derived from an N-mid-ocean ridge basalts-like mantle source with varied suprasubduction-zone (SSZ) signatures and were characterized by crystallization sequences from wet magmas, suggesting typical SSZ-affinity ophiolites. Permian and Carboniferous SSZ ophiolites in the central Qiangtang provide robust evidence for the existence and evolution of an ancient ocean basin. Combining with previous studies on high-pressure metamorphic rocks and pelagic radiolarian cherts, and with tectonostratigraphic and paleontological data, we support the LSSZ as representing the main suture of the Paleo-Tethys Ocean which probably existed and evolved from Devonian to Triassic. The opening and demise of the Paleo-Tethys Ocean dominated the formation of the major framework for the East and/or Southeast Asia.

  12. Human impacts to mountain streams

    Science.gov (United States)

    Wohl, Ellen

    2006-09-01

    Mountain streams are here defined as channel networks within mountainous regions of the world. This definition encompasses tremendous diversity of physical and biological conditions, as well as history of land use. Human effects on mountain streams may result from activities undertaken within the stream channel that directly alter channel geometry, the dynamics of water and sediment movement, contaminants in the stream, or aquatic and riparian communities. Examples include channelization, construction of grade-control structures or check dams, removal of beavers, and placer mining. Human effects can also result from activities within the watershed that indirectly affect streams by altering the movement of water, sediment, and contaminants into the channel. Deforestation, cropping, grazing, land drainage, and urbanization are among the land uses that indirectly alter stream processes. An overview of the relative intensity of human impacts to mountain streams is provided by a table summarizing human effects on each of the major mountainous regions with respect to five categories: flow regulation, biotic integrity, water pollution, channel alteration, and land use. This table indicates that very few mountains have streams not at least moderately affected by land use. The least affected mountainous regions are those at very high or very low latitudes, although our scientific ignorance of conditions in low-latitude mountains in particular means that streams in these mountains might be more altered than is widely recognized. Four case studies from northern Sweden (arctic region), Colorado Front Range (semiarid temperate region), Swiss Alps (humid temperate region), and Papua New Guinea (humid tropics) are also used to explore in detail the history and effects on rivers of human activities in mountainous regions. The overview and case studies indicate that mountain streams must be managed with particular attention to upstream/downstream connections, hillslope

  13. Pre-Carboniferous sedimentary sequences of the northeastern flank of the Parana basin and southwestern of the Parnaiba basin and its uraniferous possibilites

    International Nuclear Information System (INIS)

    Andrade, S.M. de; Camarco, P.E.N.

    1982-01-01

    The analyses of the already existent geological data of the northeastern flank of the Parana Basin and the Southwestern flank of the Parnaiba Basin, added to new data from drilling and geological mapping allowed a better knowledge of the stratigraphy of the pre-carboniferous sedimentary sequences (silurian and devonian ages) as well as provided subsidies for the definition of its uranium possibilites. Besides the already known uranium deposits of the Ponta Grossa Formation, is should be considered as worth while of prospecting the Pimenteiras Formation. (Author) [pt

  14. Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran

    Directory of Open Access Journals (Sweden)

    Shakerardakani Farzaneh

    2017-06-01

    Full Text Available In this paper, we present detailed field observations, chronological, geochemical and Sr–Nd isotopic data and discuss the petrogenetic aspects of two types of mafic dykes, of alkaline to subalkaline nature. The alkaline mafic dykes exhibit a cumulate to foliated texture and strike NW–SE, parallel to the main trend of the region. The 40Ar/39Ar amphibole age of 321.32 ± 0.55 Ma from an alkaline mafic dyke is interpreted as an indication of Carboniferous cooling through ca. 550 °C after intrusion of the dyke into the granitic Galeh-Doz orthogneiss and Amphibolite-Metagabbro units, the latter with Early Carboniferous amphibolite facies grade metamorphism and containing the Dare-Hedavand metagabbro with a similar Carboniferous age. The alkaline and subalkaline mafic dykes can be geochemically categorized into those with light REE-enriched patterns [(La/YbN = 8.32–9.28] and others with a rather flat REE pattern [(La/YbN = 1.16] and with a negative Nb anomaly. Together, the mafic dykes show oceanic island basalt to MORB geochemical signature, respectively. This is consistent, as well, with the (Tb/YbPM ratios. The alkaline mafic dykes were formed within an enriched mantle source at depths of ˃ 90 km, generating a suite of alkaline basalts. In comparison, the subalkaline mafic dykes were formed within more depleted mantle source at depths of ˂ 90 km. The subalkaline mafic dyke is characterized by 87Sr/86Sr ratio of 0.706 and positive ɛNd(t value of + 0.77, whereas 87Sr/86Sr ratio of 0.708 and ɛNd(t value of + 1.65 of the alkaline mafic dyke, consistent with the derivation from an enriched mantle source. There is no evidence that the mafic dykes were affected by significant crustal contamination during emplacement. Because of the similar age, the generation of magmas of alkaline mafic dykes and of the Dare-Hedavand metagabbro are assumed to reflect the same process of lithospheric or asthenospheric melting. Carboniferous back-arc rifting is

  15. Soft-sediment deformation structures from an ice-marginal storm-tide interactive system, Permo-Carboniferous Talchir Formation, Talchir Coalbasin, India

    Science.gov (United States)

    Bhattacharya, H. N.; Bhattacharya, Biplab

    2010-01-01

    Permo-Carboniferous Talchir Formation, Talchir Coalbasin, India, records sedimentation during a phase of climatic amelioration in an ice-marginal storm-affected shelf. Evidences of subtidal processes are preserved only under thick mud drapes deposited during waning storm phases. Various soft-sediment deformation structures in some sandstone/siltstone-mudstone interbeds, like syn-sedimentary faults, deformed laminations, sand-silt flows, convolute laminations and various flame structures, suggest liquefaction and fluidization of the beds due to passage of syn-depositional seismic shocks. In the Late Paleozoic ice-marginal shelf, such earthquake tremors could be generated by crustal movements in response to glacioisostatic adjustments of the basin floor.

  16. Ice marginal fluctuations during the Weichselian glaciation in Fennoscandia, a literature review

    International Nuclear Information System (INIS)

    Lokrantz, Hanna; Sohlenius, Gustav

    2006-12-01

    This report presents an overview regarding ice marginal fluctuations during the last glacial, the Weichselian. It is focusing on marginal positions in Sweden with surroundings. The results are used to calibrate a computer simulation of the Weichselian ice sheet. The report also contains some information regarding basal conditions beneath the Swedish part of the Weichselian ice sheet. This information will be used to validate the results of the simulation of the Weichselian ice sheet. The Weichselian glaciation started 115 ka BP (thousands of years before present) and ended at the transition to the Holocene 11.5 ka BP. Terrestrial and marine records show that ice volumes fluctuated drastically during the Weichselian. The marine isotope record shows the global variations in climate and ice volume during the last ice age and has been divided into Marine Isotope Stages (MIS), which are well dated (MIS5d to MIS 2). Dating of terrestrial records is, however, problematic due to stratigraphical gaps and deposits, which are difficult to date. In many areas the timing of local and regional ice marginal fluctuations, prior to the Last Glacial Maximum (LGM), is therefore poorly understood. Age attribution of terrestrial deposits is often interpreted from bio- and litostratigraphical information, which has been correlated to other records, e.g. marine stratigraphies. The marine record from Early Weichselian (MIS 5d-5a) shows that two relatively warm periods, interstadials (MIS 5c and 5a), prevailed 105-9 ka BP and 85-74 ka BP. After MIS 5a global ice volume increased and remained large throughout Middle Weichselian (74-24 ka BP). During the LGM (c 21 ka BP), before the onset of the deglaciation, the ice volume was at its largest. Stratigraphical data indicate at least two periods with ice-free conditions in northern Fennoscandia, which have been correlated with the two early Weichselian interstadials Broerup and Odderade (MIS 5c and 5a). Few absolute dates have, however, been

  17. Ice marginal fluctuations during the Weichselian glaciation in Fennoscandia, a literature review

    Energy Technology Data Exchange (ETDEWEB)

    Lokrantz, Hanna; Sohlenius, Gustav [Geological Survey of Sweden, Uppsala (Sweden)

    2006-12-15

    This report presents an overview regarding ice marginal fluctuations during the last glacial, the Weichselian. It is focusing on marginal positions in Sweden with surroundings. The results are used to calibrate a computer simulation of the Weichselian ice sheet. The report also contains some information regarding basal conditions beneath the Swedish part of the Weichselian ice sheet. This information will be used to validate the results of the simulation of the Weichselian ice sheet. The Weichselian glaciation started 115 ka BP (thousands of years before present) and ended at the transition to the Holocene 11.5 ka BP. Terrestrial and marine records show that ice volumes fluctuated drastically during the Weichselian. The marine isotope record shows the global variations in climate and ice volume during the last ice age and has been divided into Marine Isotope Stages (MIS), which are well dated (MIS5d to MIS 2). Dating of terrestrial records is, however, problematic due to stratigraphical gaps and deposits, which are difficult to date. In many areas the timing of local and regional ice marginal fluctuations, prior to the Last Glacial Maximum (LGM), is therefore poorly understood. Age attribution of terrestrial deposits is often interpreted from bio- and litostratigraphical information, which has been correlated to other records, e.g. marine stratigraphies. The marine record from Early Weichselian (MIS 5d-5a) shows that two relatively warm periods, interstadials (MIS 5c and 5a), prevailed 105-9 ka BP and 85-74 ka BP. After MIS 5a global ice volume increased and remained large throughout Middle Weichselian (74-24 ka BP). During the LGM (c 21 ka BP), before the onset of the deglaciation, the ice volume was at its largest. Stratigraphical data indicate at least two periods with ice-free conditions in northern Fennoscandia, which have been correlated with the two early Weichselian interstadials Broerup and Odderade (MIS 5c and 5a). Few absolute dates have, however, been

  18. Protected areas in mountains

    Directory of Open Access Journals (Sweden)

    Hamilton, L. S.

    2006-12-01

    Full Text Available

    The importance of a global Protected Areas Network in sustaining appropriate mountain development is presented in this paper. Present status of the world’s “official” Protected Areas in the UN List, and the proportion that are in mountain areas, and including international designations (World Heritage and Biosphere Reserves. Current and future challenges in the management of these special areas are also commented.



    El autor destaca la importancia de una Red Mundial de Espacios Protegidos para el desarrollo sostenible de las montañas. Comenta luego el estatus actual de las Áreas Protegidas “oficiales” del Mundo en la Lista de las Naciones Unidas y qué proporción de ellas forma parte de las montañas, sin olvidar las figuras internacionales de protección como Patrimonio de la Humanidad y Reservas de Biosfera. Para terminar, se discuten los problemas de gestión actuales y futuros de estas áreas tan especiales

  19. SP mountain data analysis

    Science.gov (United States)

    Rawson, R. F.; Hamilton, R. E.; Liskow, C. L.; Dias, A. R.; Jackson, P. L.

    1981-01-01

    An analysis of synthetic aperture radar data of SP Mountain was undertaken to demonstrate the use of digital image processing techniques to aid in geologic interpretation of SAR data. These data were collected with the ERIM X- and L-band airborne SAR using like- and cross-polarizations. The resulting signal films were used to produce computer compatible tapes, from which four-channel imagery was generated. Slant range-to-ground range and range-azimuth-scale corrections were made in order to facilitate image registration; intensity corrections were also made. Manual interpretation of the imagery showed that L-band represented the geology of the area better than X-band. Several differences between the various images were also noted. Further digital analysis of the corrected data was done for enhancement purposes. This analysis included application of an MSS differencing routine and development of a routine for removal of relief displacement. It was found that accurate registration of the SAR channels is critical to the effectiveness of the differencing routine. Use of the relief displacement algorithm on the SP Mountain data demonstrated the feasibility of the technique.

  20. 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

  1. YUCCA MOUNTAIN PROJECT - A BRIEFING -

    International Nuclear Information System (INIS)

    2003-01-01

    This report has the following articles: Nuclear waste--a long-term national problem; Spent nuclear fuel; High-level radioactive waste; Radioactivity and the environment; Current storage methods; Disposal options; U.S. policy on nuclear waste; The focus on Yucca Mountain; The purpose and scope of the Yucca Mountain Project; The approach for permanently disposing of waste; The scientific studies at Yucca Mountain; The proposed design for a repository at Yucca Mountain; Natural and engineered barriers would work together to isolate waste; Meticulous science and technology to protect people and the environment; Licensing a repository; Transporting waste to a permanent repository; The Environmental Impact Statement for a repository; Current status of the Yucca Mountain Project; and Further information available on the Internet

  2. EVOLUTION OF THE ELBRUS GLACIATION SINCE THE MID XIX CENTURY UNDER CHANGING CLIMATE. KEY FINDINGS OF THE GLACIO-CARTOGRAPHICAL MONITORING

    Directory of Open Access Journals (Sweden)

    Yevgeniy Zolotarev

    2010-01-01

    Full Text Available Changes in the area and volume that have been occurring from the middle of the XIX century within the largest in Europe Elbrus glaciation were studied using lichenometry and digital cartography methods. There were cyclical, approximately 55 years long, frontal fluctuations of glaciers Bolshoi Azau (the largest Elbrus glacier and Dzhankuat (which is representative of all Central Caucasus glaciation. Quantitative data on changes in the area and volume of the Elbrus glaciation indicated that the greatest rates of its retreat coincided with the 1850–1887 period. Beginning in 1887, the area reduction was occurring practically evenly through time while the decrease in its volume has even slowed down. These facts suggest that global climate warming, which alternated with short-term cooling periods, began in the middle of the XIX century after the end of the Little Ice Age. The warming was most likely due to natural rather than anthropogenic causes.

  3. Links between CO2, glaciation and water flow: reconciling the Cenozoic history of the Antarctic Circumpolar Current

    International Nuclear Information System (INIS)

    Ladant, J.B.; Donnadieu, Y.; Dumas, C.

    2014-01-01

    The timing of the onset of the Antarctic Circumpolar Current (ACC) is a crucial event of the Cenozoic because of its cooling and isolating effect over Antarctica. It is intimately related to the glaciations occurring throughout the Cenozoic from the Eocene - Oligocene (EO) transition (∼ 34 Ma) to the middle Miocene glaciations (∼ 13.9 Ma). However, the exact timing of the onset remains debated, with evidence for a late Eocene setup contradicting other data pointing to an occurrence closer to the Oligocene - Miocene (OM) boundary. In this study, we show the potential impact of the Antarctic ice sheet on the initiation of a strong proto- ACC at the EO boundary. Our results reveal that the regional cooling effect of the ice sheet increases sea ice formation, which disrupts the meridional density gradient in the Southern Ocean and leads to the onset of a circumpolar current and its progressive strengthening. We also suggest that subsequent variations in atmospheric CO 2 , ice sheet volumes and tectonic reorganizations may have affected the ACC intensity after the Eocene - Oligocene transition. This allows us to build a hypothesis for the Cenozoic evolution of the Antarctic Circumpolar Current that may provide an explanation for the second initiation of the ACC at the Oligocene - Miocene boundary while reconciling evidence supporting both early Oligocene and early Miocene onset of the ACC. (authors)

  4. New Zealand Maritime Glaciation: Millennial-Scale Southern Climate Change Since 3.9 Ma

    Science.gov (United States)

    Carter, Robert M.; Gammon, Paul

    2004-06-01

    Ocean Drilling Program Site 1119 is ideally located to intercept discharges of sediment from the mid-latitude glaciers of the New Zealand Southern Alps. The natural gamma ray signal from the site's sediment core contains a history of the South Island mountain ice cap since 3.9 million years ago (Ma). The younger record, to 0.37 Ma, resembles the climatic history of Antarctica as manifested by the Vostok ice core. Beyond, and back to the late Pliocene, the record may serve as a proxy for both mid-latitude and Antarctic polar plateau air temperature. The gamma ray signal, which is atmospheric, also resembles the ocean climate history represented by oxygen isotope time series.

  5. European mountain biodiversity

    Directory of Open Access Journals (Sweden)

    Nagy, Jennifer

    1998-12-01

    Full Text Available This paper, originally prepared as a discussion document for the ESF Exploratory Workshop «Trends in European Mountain Biodiversity - Research Planning Workshop», provides an overview of current mountain biodiversity research in Europe. It discusses (a biogeographical trends, (b the general properties of biodiversity, (c environmental factors and the regulation of biodiversity with respect to ecosystem function, (d the results of research on mountain freshwater ecosystems, and (e climate change and air pollution dominated environmental interactions.- The section on biogeographical trends highlights the importance of altitude and latitude on biodiversity. The implications of the existence of different scales over the different levels of biodiversity and across organism groups are emphasised as an inherent complex property of biodiversity. The discussion on ecosystem function and the regulation of biodiversity covers the role of environmental factors, productivity, perturbation, species migration and dispersal, and species interactions in the maintenance of biodiversity. Regional and long-term temporal patterns are also discussed. A section on the relatively overlooked topic of mountain freshwater ecosystems is presented before the final topic on the implications of recent climate change and air pollution for mountain biodiversity.

    [fr] Ce document a été préparé à l'origine comme une base de discussion pour «ESF Exploratory Workshop» intitulé «Trends in European Mountain Biodiversity - Research Planning Workshop»; il apporte une vue d'ensemble sur les recherches actuelles portant sur la biodiversité des montagnes en Europe. On y discute les (a traits biogéographiques, (b les caractéristiques générales- de la biodiversité, (c les facteurs environnementaux et la régulation de la biodiversité par rapport à la fonction des écosystèmes, (d les résultats des études sur les écosystèmes aquatiques des montagnes et (e les

  6. The comparative phylogeography of east coast estuarine fishes in formerly glaciated sites: Persistence versus recolonization in Cyprinodon variegatus ovinus and Fundulus heteroclitus macrolepidotus.

    Science.gov (United States)

    Haney, Robert A; Dionne, Michelle; Puritz, Jon; Rand, David M

    2009-01-01

    Species distributions may be dramatically affected by climatic variability, such as occurred during Pleistocene glaciation. Populations of coastal organisms could have been affected directly by ice movement or through sea level change. Response could involve shifts in distribution southwards or persistence through the full range or in limited high-latitude refugia. Comparative studies of the response of ecologically similar species can provide a useful complement to those examining response across disparate species in defining what parameters influence persistence. Patterns of mitochondrial genetic variation in 2 estuarine fish subspecies from the Northwest Atlantic, Fundulus heteroclitus macrolepidotus and Cyprinodon variegatus ovinus, indicate that ecological similarity does not necessarily predict propensity for glacial persistence. Fundulus heteroclitus macrolepidotus is highly diverse in glaciated regions, with isolated populations whose origins predate the last glacial maximum and may have recently expanded it's range to the south from New England. However, within glaciated regions, signals of population growth and distributional shifts indicate a dynamic Pleistocene history for F. h. macrolepidotus, in contrast with recent studies involving microsatellites. A different pattern is found in C. v. ovinus, which is depauperate in formerly glaciated sites, with a clear signal of recent recolonization of glaciated regions from the south. Genetic differentiation in glaciated areas is consistent with isolation after glacial withdrawal. In C. v. ovinus, rapidly evolving microsatellite loci show a similar pattern to mitochondrial DNA but may be reaching equilibrium on small spatial scales. These contrasting patterns of variation illustrate how ecologically similar species can respond to large-scale environmental change in distinct ways.

  7. Plate tectonics hiati as the cause of global glaciations: 2. The late Proterozoic 'Snowball Earth'

    Science.gov (United States)

    Osmaston, M. F.

    2003-04-01

    A fundamental reappraisal of the mechanisms that drive plate tectonics has yielded the remarkable conclusion that, for at least the past 130 Ma, the principal agent has not been ridge-push or slab-pull but a CW-directed torque (probably of electromagnetic origin at the CMB) reaching the deep (>600 km, e.g.[1]) tectospheric keel of the Antarctica craton. Major changes in spreading direction marked both ends of the 122--85 Ma Cretaceous Superchron and started by forming the Ontong Java Plateau. Action of MORs as gearlike linkages has driven Africa and India CCW since Gondwana breakup and continues to drive the Pacific plate CCW. In the Arctic there is now no cratonic keel to pick up any corresponding polar torque, so northern hemisphere plate tectonics is far less active. The thesis of this contribution is that in the Neoproterozoic the lack of cratons at high latitudes would have deprived plate tectonics of this motivation, causing MORs to die (see below) and a major fall in sea-level, leading to global glaciation as outlined in Part 1 for the Huronian events. Like that seen during that first hiatus, dyke-swarm volcanism could have arisen from thermal shrinkage of the global lithosphere, providing CO2 and ash-covering that interrrupted glacial episodes. In oceanic settings this volcanism would have lowered pH and supplied Fe2+ for shallow bio-oxygenic action to deposit as BIF. My multifacet studies of the subduction process convince me that the rapid development of "flat-slab" interface profiles involves the physical removal of hanging-wall material in front of the downbend by basal subduction tectonic erosion (STE). Historically this, and its inferred ubiquity in the Archaean as the precursor to PSM (Part 1), suggests that the required subducting-plate buoyancy is thermal. Accordingly, a redesign [2] of the MOR process has incorporated the heat-containing LVZ as an integral part of the plate and luckily provides a lot more ridge-push to ensure the subduction of

  8. Reservoir characteristics and control factors of Carboniferous volcanic gas reservoirs in the Dixi area of Junggar Basin, China

    Directory of Open Access Journals (Sweden)

    Ji'an Shi

    2017-02-01

    Full Text Available Field outcrop observation, drilling core description, thin-section analysis, SEM analysis, and geochemistry, indicate that Dixi area of Carboniferous volcanic rock gas reservoir belongs to the volcanic rock oil reservoir of the authigenic gas reservoir. The source rocks make contact with volcanic rock reservoir directly or by fault, and having the characteristics of near source accumulation. The volcanic rock reservoir rocks mainly consist of acidic rhyolite and dacite, intermediate andesite, basic basalt and volcanic breccia: (1 Acidic rhyolite and dacite reservoirs are developed in the middle-lower part of the structure, have suffered strong denudation effect, and the secondary pores have formed in the weathering and tectonic burial stages, but primary pores are not developed within the early diagenesis stage. Average porosity is only at 8%, and the maximum porosity is at 13.5%, with oil and gas accumulation showing poor performance. (2 Intermediate andesite and basic basalt reservoirs are mainly distributed near the crater, which resembles the size of and suggests a volcanic eruption. Primary pores are formed in the early diagenetic stage, secondary pores developed in weathering and erosion transformation stage, and secondary fractures formed in the tectonic burial stage. The average porosity is at 9.2%, and the maximum porosity is at 21.9%: it is of the high-quality reservoir types in Dixi area. (3 The volcanic breccia reservoir has the same diagenetic features with sedimentary rocks, but also has the same mineral composition with volcanic rock; rigid components can keep the primary porosity without being affected by compaction during the burial process. At the same time, the brittleness of volcanic breccia reservoir makes it easily fracture under the stress; internal fracture was developmental. Volcanic breccia developed in the structural high part and suffered a long-term leaching effect. The original pore-fracture combination also made

  9. Geology at Yucca Mountain

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    Both advocates and critics disagree on the significance and interpretation of critical geological features which bear on the safety and suitability of Yucca Mountain as a site for the construction of a high-level radioactive waste repository. Critics believe that there is sufficient geological evidence to rule the site unsuitable for further investigation. Some advocates claim that there is insufficient data and that investigations are incomplete, while others claim that the site is free of major obstacles. We have expanded our efforts to include both the critical evaluations of existing geological and geochemical data and the collection of field data and samples for the purpose of preparing scientific papers for submittal to journals. Summaries of the critical reviews are presented in this paper

  10. The Yucca Mountain tours

    International Nuclear Information System (INIS)

    Shepard, N.F.; Champagne, D.L.

    1992-01-01

    In 1978, Mderthaner et al. observed that opposition to nuclear facilities was lowest near the facility. This suggested that opposition decreased as familiarity with the facility increased, with distance from the facility as an inverse measure of familiarity. In this paper, the authors analyze data from the literature supporting this hypothesis and examine a poll of 1200 public visitors to the candidate repository site at Yucca Mountain, Nevada, in March through June 1991. The tour poll and independent pools show that most Nevadans support the present scientific investigation of the site while opposing the repository. Among the visitors, support for the investigation increased from 66 to 90 percent, which we attribute to increased familiarity

  11. Hydrological system dynamics of glaciated Karnali River Basin Nepal Himalaya using J2000 Hydrological model

    Science.gov (United States)

    Khatiwada, K. R.; Nepal, S.; Panthi, J., Sr.; Shrestha, M.

    2015-12-01

    Hydrological modelling plays an important role in understanding hydrological processes of a catchment. In the context of climate change, the understanding of hydrological characteristic of the catchment is very vital to understand how the climate change will affect the hydrological regime. This research facilitates in better understanding of the hydrological system dynamics of a himalayan mountainous catchment in western Nepal. The Karnali River, longest river flowing inside Nepal, is one of the three major basins of Nepal, having the area of 45269 sq. km. is unique. The basin has steep topography and high mountains to the northern side. The 40% of the basin is dominated by forest land while other land cover are: grass land, bare rocky land etc. About 2% of the areas in basin is covered by permanent glacier apart from that about 12% of basin has the snow and ice cover. There are 34 meteorological stations distributed across the basin. A process oriented distributed J2000 hydrologial model has been applied to understand the hydrological system dynamics. The model application provides distributed output of various hydrological components. The J2000 model applies Hydrological Response Unit (HRU) as a modelling entity. With 6861 HRU and 1010 reaches, the model was calibrated (1981-1999) and validated (2000-2004) at a daily scale using split-sample test. The model is able to capture the overall hydrological dynamics well. The rising limbs and recession limbs are simulated equally and with satisfactory ground water conditions. Based on the graphical and statistical evaluation of the model performance the model is able to simulate hydrological processes fairly well. Calibration shows that Nash Sutcliffe efficiency is 0.91, coefficient of determination is 0.92 Initial observation shows that during the pre-monsoon season(March to May) the glacial runoff is 25% of the total discharge while in the monsoon(June to September) season it is only 13%. The surface runoff

  12. The Carboniferous to Jurassic evolution of the pre-Alpine basement of Crete: Constraints from U-Pb and U-(Th)-Pb dating of orthogneiss, fission-track dating of zircon, structural and petrological data

    Czech Academy of Sciences Publication Activity Database

    Romano, S. S.; Brix, M. R.; Dörr, K.; Fiala, Jiří; Krenn, E.; Zulauf, G.

    2006-01-01

    Roč. 260, - (2006), s. 69-90 ISSN 0375-6440 Institutional research plan: CEZ:AV0Z30130516 Keywords : tectonic-evolution * Carboniferous * Jurassic * uranium-lead-dating * orthogneiss * fission-track-dating * zircon * structural-geology * petrology * metamorphism * high-temperature Subject RIV: DB - Geology ; Mineralogy

  13. Glaciation history of Queen Maud Land (Antarctica) – New exposure data from nunataks

    Energy Technology Data Exchange (ETDEWEB)

    Strub, E.; Wiesel, H. [Division of Nuclear Chemistry, University of Cologne, Cologne (Germany); Delisle, G. [Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover (Germany); Binnie, S.A.; Liermann, A.; Dunai, T.J. [Institute of Geology and Mineralogy, University of Cologne, Cologne (Germany); Herpers, U. [Division of Nuclear Chemistry, University of Cologne, Cologne (Germany); Dewald, A.; Heinze, S. [Institute of Nuclear Physics, University of Cologne, Cologne (Germany); Christl, M. [Laboratory of Ion Beam Physics, ETH Zurich (Switzerland); Coenen, H.H. [Division of Nuclear Chemistry, University of Cologne, Cologne (Germany); Institute of Nuclear Chemistry (INM-5), Research Centre Jülich (Germany)

    2015-10-15

    Terrestrial cosmogenic nuclide exposure ages for the Wohlthat Massif (Antarctica), have previously been determined. This was done with {sup 10}Be and {sup 26}Al measurements by accelerator mass spectrometry (AMS) at the AMS facility at the ETH Zurich. In order to determine the extent to which the results from the Wohlthat Massif are of regional significance, additional samples were collected during the 2007 BGR-expedition “Queenmet”. Two of the Steingarden Nunataks (isolated mountain peaks) were chosen as sampling locations, approximately 100 km south-east of the Wohlthat Massif/Queen Maud Land, at the edge of the Polar Plateau. Quartz rich samples were collected at different elevations on the nunataks to reconstruct an elevation-dependent exposure history. The in situ produced cosmogenic nuclides {sup 10}Be and {sup 26}Al in these samples were measured by AMS. During sample processing the quartz separates were prepared by two different methods (Kohl and Nishiizumi, 1992, Altmaier, 2000) and measurements were performed at two different facilities (CologneAMS und Zurich AMS) to confirm the reproducibility of the results. The new results of rock surface exposure ages reveal that the exposure of the lower nunatak to cosmic radiation started between 0.65 and 1.1 Ma ago, while the more elevated regions of the second nunatak were apparently above the ice 3–4 Ma ago.

  14. A mountain of millipedes IV

    DEFF Research Database (Denmark)

    Enghoff, Henrik

    2016-01-01

    Two species of the genus Prionopetalum Attems, 1909, are recorded from the Udzungwa Mountains: P. asperginis sp. nov. and P. kraepelini (Attems, 1896). Prionopetalum stuhlmanni Attems, 1914, is synonymized under P. kraepelini. Odontopyge fasciata Attems, 1896, is transferred from Prionopetalum...

  15. The Table Mountain Field Site

    Data.gov (United States)

    Federal Laboratory Consortium — The Table Mountain Field Site, located north of Boulder, Colorado, is designated as an area where the magnitude of strong, external signals is restricted (by State...

  16. Geography and Weather: Mountain Meterology.

    Science.gov (United States)

    Mogil, H. Michael; Collins, H. Thomas

    1990-01-01

    Provided are 26 ideas to help children explore the effects of mountains on the weather. Weather conditions in Nepal and Colorado are considered separately. Nine additional sources of information are listed. (CW)

  17. Extinction of Harrington's mountain goat

    International Nuclear Information System (INIS)

    Mead, J.I.; Martin, P.S.; Euler, R.C.; Long, A.; Jull, A.J.T.; Toolin, L.J.; Donahue, D.J.; Linick, T.W.

    1986-01-01

    Keratinous horn sheaths of the extinct Harrington's mountain goat, Oreamnos harringtoni, were recovered at or near the surface of dry caves of the Grand Canyon, Arizona. Twenty-three separate specimens from two caves were dated nondestructively by the tandem accelerator mass spectrometer (TAMS). Both the TAMS and the conventional dates indicate that Harrington's mountain goat occupied the Grand Canyon for at least 19,000 years prior to becoming extinct by 11,160 +/- 125 radiocarbon years before present. The youngest average radiocarbon dates on Shasta ground sloths, Nothrotheriops shastensis, from the region are not significantly younger than those on extinct mountain goats. Rather than sequential extinction with Harrington's mountain goat disappearing from the Grand Canyon before the ground sloths, as one might predict in view of evidence of climatic warming at the time, the losses were concurrent. Both extinctions coincide with the regional arrival of Clovis hunters

  18. The Dilemma of Mountain Roads

    Science.gov (United States)

    Mountain roads and trails are proliferating throughout developing Southeast Asia with severe but largely unrecognized long-term consequences related to effects of landslides and surface erosion on communities and downstream resources.

  19. Yucca Mountain Project public interactions

    International Nuclear Information System (INIS)

    Reilly, B.E.

    1990-01-01

    The US Department of Energy (DOE) is committed to keeping the citizens of Nevada informed about activities that relate to the high-level nuclear waste repository program. This paper presents an overview of the Yucca Mountain Project's public interaction philosophy, objectives, activities and experiences during the two years since Congress directed the DOE to conduct site characterization activities only for the Yucca Mountain site

  20. The regional species richness and genetic diversity of Arctic vegetation reflect both past glaciations and current climate

    DEFF Research Database (Denmark)

    Stewart, L.; Alsos, Inger G.; Bay, Christian

    2016-01-01

    Aim The Arctic has experienced marked climatic differences between glacial and interglacial periods and is now subject to a rapidly warming climate. Knowledge of the effects of historical processes on current patterns of diversity may aid predictions of the responses of vegetation to future climate...... species richness of the vascular plant flora of 21 floristic provinces and examined local species richness in 6215 vegetation plots distributed across the Arctic. We assessed levels of genetic diversity inferred from amplified fragment length polymorphism variation across populations of 23 common Arctic...... size compared to the models of bryophyte and lichen richness. Main conclusion Our study suggests that imprints of past glaciations in Arctic vegetation diversity patterns at the regional scale are still detectable today. Since Arctic vegetation is still limited by post-glacial migration lag...

  1. A wireless partially glaciated watershed in a virtual globe: Integrating data, models, and visualization to increase climate change understanding

    Science.gov (United States)

    Jones, J.; Hood, E.; Fatland, D. R.; Berner, L.; Heavner, M.; Connor, C.; O'Brien, W.

    2008-12-01

    SEAMONSTER, a NASA funded sensor web project, is the SouthEast Alaska MOnitoring Network for Science, Telecommunications, Education and Research. SEAMONSTER is operating in the partially glaciated Mendenhall and Lemon Creek Watersheds, in the Juneau area, on the margins of the Juneau Icefield. These watersheds are studied for both 1. long term monitoring of changes, and 2. detection and analysis of transient events (such as glacier lake outburst floods). The diverse sensors (meteorological, dual frequency GPS, water quality, lake level, etc), power and bandwidth constraints, and competing time scales of interest require autonomous reactivity of the sensor web. The sensors are deployed throughout two partially glaciated watersheds and facilitated data acquisition in temperate rain forest, alpine, lacustrine, and glacial environments. Understanding these environments is important for public understanding of climate change. These environments are geographically isolated, limiting public access to, and understanding of, such locales. In an effort to inform the general public and primary educators about the basic processes occurring in these unique natural systems, we have developed an interactive website. This web portal supplements and enhances environmental science primary education by providing educators and students with interactive access to basic information from the glaciological, hydrological, and meteorological systems we are studying. In addition, we have developed an interactive virtual tour of the Lemon Glacier and its watershed. The focus of this presentation is using the data gathered by the SEAMONSTER sensor web, coupled with a temperature-indexed glacial melt model, to educate students and the public on topics ranging from modeling responses due to environmental changes to glacial hydrology. The interactive SEAMONSTER web site is the primary source for visualizing the data, while Google Earth can be used to visualize the isolated Lemon Creek watershed

  2. Cyclostratigraphic constraints on the duration of the Datangpo Formation and the onset age of the Nantuo (Marinoan) glaciation in South China

    Science.gov (United States)

    Bao, Xiujuan; Zhang, Shihong; Jiang, Ganqing; Wu, Huaichun; Li, Haiyan; Wang, Xinqiang; An, Zhengze; Yang, Tianshui

    2018-02-01

    Constructing an accurate timeline is critical for reconstructing the Earth systems through critical transitions in climate, geochemistry, and life. Existing dates constrain synchronous initiation (ca. 717 Ma) and termination (ca. 660 Ma) of the Sturtian glaciation from multiple continents. The termination of the younger Marinoan glaciation is also well dated at ca. 635 Ma, but the onset of this glaciation is only roughly constrained as ≤ ca. 654 Ma (South China) and ≥ ca. 639 Ma (Namibia). To test if the Marinoan glaciation started close to ca. 654 Ma or ca. 639 Ma, we have conducted a cyclostratigraphic study on the Cryogenian non-glacial Datangpo Formation that conformably overlies and underlies Sturtian and Marinoan glacial diamictites, respectively, in a deep-water basin section in South China. A total of 28,765 magnetic susceptibility (MS) measurements from a drillcore of the 292-m-thick, muddy siltstone- and shale-dominated Datangpo Formation are used for cyclostratigraphic analysis. The results reveal significant decameter- to meter-scale sedimentary cycles of 16-12 m, 3.6-3.0 m, 1.0-0.8 m, and 0.6-0.4 m. The ratios of these cycle wavelengths match well with those of the Milankovitch cycles calibrated for the Cryogenian Period. The established astrochronologic time scale suggests that the duration of the Datangpo Formation is about 9.8 million years. Together with the radiometric age of ca. 660 Ma for the termination of the Sturtian glaciation, the cyclostratigraphic data suggest that the Nantuo (Marinoan) glaciation in South China initiated at ca. 650 Ma, which is slightly younger than but consistent with the ca. 654 Ma U-Pb age from the top of the Datangpo Formation in shelf sections. This age, however, is significantly older than the ages obtained from Marinoan-age glacial diamictites in South China (ca. 636 Ma) and Namibia (ca. 639 Ma). Given that most of the shelf sections may have suffered from glacial erosion, obtaining the onset age of the

  3. Testing the efficiency of nested barriers to dispersal in the Mediterranean high mountain plant Edraianthus graminifolius (Campanulaceae).

    Science.gov (United States)

    Surina, Boštjan; Schneeweiss, Gerald M; Glasnović, Peter; Schönswetter, Peter

    2014-06-01

    Due to strong spatial heterogeneity and limited Pleistocene glaciation, the Balkan Peninsula is a major European biodiversity hot spot. Surprisingly little, however, is known about patterns and processes of intraspecific diversification of its biota in general and of high-altitude species in particular. A well-suited system to test hypotheses with respect to various isolating factors acting at different geographic scales and to explore full-range phylogeographic patterns on the Balkan Peninsula is Edraianthus graminifolius (Campanulaceae), distributed in the western Balkan mountain systems, the southwestern Carpathians and the Apennine Peninsula. To this end, we used a dense population sampling and employed amplified fragment length polymorphism (AFLP) markers and plastid DNA sequences supplemented by ecological niche modelling. The strongest splits were inferred to separate southern and northern Balkan populations from the central ones, from where range extension occurred to the Carpathians and, in more recent times, once or twice to the Apennine Peninsula. The three genetic groups in the western Balkan Peninsula were remarkably congruent among molecular markers, suggesting that the barriers to gene flow acted over long time periods facilitating allopatric differentiation. Each main group of Balkan populations contained genetically and geographically distinct subgroups, which likely are the result of local refugia during warmer periods. Evidently, the topographically highly complex and during the Last Glacial Maximum only locally glaciated Balkan Peninsula is a hot spot of species richness and endemism as well as a sanctuary of intraspecific genetic diversity, even if the underlying causes remain insufficiently understood. © 2014 John Wiley & Sons Ltd.

  4. The potential drivers in forming avian biodiversity hotspots in the East Himalaya Mountains of Southwest China.

    Science.gov (United States)

    Lei, Fumin; Qu, Yanhua; Song, Gang; Alström, Per; Fjeldså, Jon

    2015-03-01

    Little has been published to describe or interpret Asian biodiversity hotspots, including those in the East Himalayan Mountains of Southwest China (HMSC), thus making necessary a review of the current knowledge. The Pliocene and Pleistocene geological and glacial histories of the Asian continent differ from those of Europe and North America, suggesting different mechanisms of speciation and extinction, and, thus, different responses to climate changes during the Quaternary glaciations. This short review summarizes potential drivers in shaping and maintaining high species richness and endemism of birds in the HMSC. The geographical location at the junction of different biogeographical realms, the wide range of habitats and climates along the extensive elevational range, the complex topography and the distinct geological history of this region have probably contributed to the evolution of an exceptionally species-rich and endemic-rich, specialized montane avian fauna. The Mountain systems in the HMSC may have provided refugia where species survived during the glacial periods and barriers for preventing species dispersal after the glacial periods. More studies are required to further test this refugia hypothesis by comparing more cold-tolerent and warm-tolerent species. © 2014 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

  5. The origins of mountain geoecology

    Directory of Open Access Journals (Sweden)

    Ives, Jack D.

    2012-05-01

    Full Text Available Mountain geoecology, as a sub-discipline of Geography, stems from the life and work of Carl Troll who, in turn, was inspired by the philosophy and mountain travels of Alexander von Humboldt. As founding chair of the IGU Commission on High-Altitude Geoecology (1968, Troll laid the foundations for inter-disciplinary and international mountain research. The paper traces the evolution of the Commission and its close links with the UNESCO Man and Biosphere Programme (1972- and the United Nations University’s mountain Project (1978-. This facilitated the formation of a major force for inclusion of a mountain chapter in AGENDA 21 during the 1992 Rio de Janeiro Herat Summit (UNCED and the related designation by the United Nations of 2002 as the International Year of Mountains. In this way, mountain geoecology not only contributed to worldwide mountain research but also entered the political arena in the struggle for sustainable mountain development and the well-being of mountain people.La geoecología de montaña, como sub-disciplina de la Geografía, entronca con la vida y trabajo de Carl Troll, quien, a su vez, fue inspirado por la filosofía y viajes de Alexander von Humboldt. Como presidente fundador de la comisión de la UGI sobre High Altitude Geoecology (1968, Troll colocó las bases para la investigación interdisciplinar e internacional de las montañas. Este trabajo presenta la evolución de la Comisión y sus estrechas relaciones con el Programa Hombre y Biosfera de UNESCO (1972- y con el Proyecto de montaña de la Universidad de Naciones Unidas (1978-. Esto facilitó la inclusión de un capítulo sobre la montaña en AGENDA 21 durante la Cumbre de la Tierra de Río de Janeiro (UNCED, y la consiguiente designación de 2002 como el Año Internacional de las Montañas por parte de Naciones Unidas. En este sentido, la geoecología de montaña no sólo contribuyó a la investigación de las montañas del mundo sino que también empujó a la pol

  6. Middle to Late Devonian–Carboniferous collapse basins on the Finnmark Platform and in the southwesternmost Nordkapp basin, SW Barents Sea

    Directory of Open Access Journals (Sweden)

    J.-B. P. Koehl

    2018-03-01

    Full Text Available The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle–Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, (i the Måsøy Fault Complex, (ii the Rolvsøya fault, and (iii the Troms–Finnmark Fault Complex. We discuss the formation of the Måsøy Fault Complex as a possible extensional splay of an overall NE–SW-trending, NW-dipping, basement-seated Caledonian shear zone, the Sørøya–Ingøya shear zone, which was partly inverted during the collapse of the Caledonides and accommodated top–NW normal displacement in Middle to Late Devonian–Carboniferous times. The Troms–Finnmark Fault Complex displays a zigzag-shaped pattern of NNE–SSW- and ENE–WSW-trending extensional faults before it terminates to the north as a WNW–ESE-trending, NE-dipping normal fault that separates the southwesternmost Nordkapp basin in the northeast from the western Finnmark Platform and the Gjesvær Low in the southwest. The WNW–ESE-trending, margin-oblique segment of the Troms–Finnmark Fault Complex is considered to represent the offshore prolongation of a major Neoproterozoic fault complex, the Trollfjorden–Komagelva Fault Zone, which is made of WNW–ESE-trending, subvertical faults that crop out on the island of Magerøya in NW Finnmark. Our results suggest that the Trollfjorden–Komagelva Fault Zone dies out to the northwest before reaching the western Finnmark Platform. We propose an alternative model for the origin of the WNW–ESE-trending segment of the Troms–Finnmark Fault Complex as a possible hard-linked, accommodation cross fault that developed along the Sørøy–Ingøya shear zone. This brittle fault decoupled the western Finnmark Platform from the southwesternmost Nordkapp basin and merged with the

  7. Glaciation control of melting rates in the mantle: U-Th systematics of young basalts from Southern Siberia and Central Mongolia

    Science.gov (United States)

    Rasskazov, S.; Chebykin, E.

    2012-04-01

    Eastern Sayans, Siberia and Hangay, Central Mongolia are mountainous uplifts effected by Quaternary volcanism, but only the former area was covered by glaciers that were as thick as 500 m. Glaciation time intervals were marked by moraines and sub-glacial hyaloclastite-bearing volcanic edifices, whereas interglacial ones were exhibited by sub-aerial "valley" flows and cinder cones. To estimate temporal variations of maximum rates of melting and mantle upwelling in the glacial and glacial-free areas, we measured radionuclides of the U-Th system for 74 samples of the Middle-Late Pleistocene through Holocene basalts by ICP-MS technique (Chebykin et al. Russian Geol. Geophys. 2004. 45: 539-556) using mass-spectrometer Agilent 7500ce. The obtained U-Th isochron ages for the Pleistocene volcanic units in the age interval of the last 400 Kyr are mostly consistent with results of K-Ar dating. The measured (230Th/238U) ratios for the Holocene basalts from both areas are within the same range of 1.08-1.16 (parentheses denote units of activity), whereas the 50 Kyr lavas yield, respectively, the higher and lower initial (230Th0/238U) ratios (1.18-1.46 and 1.05-1.13). This discrepancy demonstrates contrast maximum rates of melting in conventional garnet peridotite sources. We suggest that this dynamical feature was provided by the abrupt Late Pleistocene deglaciation that caused the mantle decompression expressed by the earlier increasing melting beneath Eastern Sayans than beneath Hangay. In the last 400 Kyr, magmatic liquids from both Eastern Sayans and Hangay showed the overall temporal decreasing (230Th0/238U) (i.e. relative increasing rates of melting and upwelling of the mantle) with the systematically lower isotopic ratios (i.e. increased mantle activity) in the former area than in the latter. The 400 Kyr phonotephrites in Hangay showed elevated concentrations of Th (6-8 ppm) and Th/U (3.7-3.9). The high (230Th0/238U) (4.3-6.0) reflected slow fractional melting

  8. Plagioclase-mantled K-feldspar in the Carboniferous porphyritic microgranite of Altenberg-Frauenstein, Eastern Erzgebirge/Krusné Hory

    Directory of Open Access Journals (Sweden)

    Axel Müller

    2002-01-01

    Full Text Available The Upper Carboniferous porphyritic microgranite of Altenberg-Frauenstein, formerly known as Granitporphyr (Dalmer 1896 and here abbreviated as GP, forms a 36 km long and up to 18 km wide complex of ring dykes related to the Teplice-Altenberg caldera in the German–Czech border region of the Eastern Erzgebirge/Krusné Hory. The microgranites are characterized by the occurrence of plagioclase-mantled K-feldspar phenocrysts. The microgranite varieties representtwo main stages of intrusion evolved from acid (GP I to intermediaterocks (GP II within the intrusion. The most acid rock (GP Icum occurs as enclaves in GP I and GP II and is interpreted as a cumulate of K-feldspar and quartz phenocrysts. The porphyritic microgranites show field, textural and geochemical evidence suggesting that some of them have formed as a result of interaction between felsic and mafic magmas. Mixing features are abundant in the porphyriticquartz-feldspar-hornblende microgranite (GP II interpreted as a hybrid rock. They are less discrete in the early phase (GP I and not obvious in the acid enclaves (GP Icum. This trend seems to reflect a continuous deflation of the magma chamber from the top to the bottom. According to the definition of rapakivi granites after Haapala and Rämö (1992, the porphyritic microgranite of Altenberg-Frauenstein may be considered as rapakivi granite although ovoid alkali feldspar megacrysts typical of classical rapakivi granites are not recorded.However, due to its Carboniferous age and being the only known granitewith rapakivi texture in the German–Czech part of the Variscan belt, the microgranite of Altenberg-Frauenstein is exceptional.

  9. Mountain biking injuries: a review.

    Science.gov (United States)

    Carmont, Michael R

    2008-01-01

    Mountain biking is a fast, exciting adventure sport with increasing numbers of participants and competitions. A search of PubMed, Medline, CINAHL, DH data, and Embase databases was performed using the following keywords: mountain, biking and injuries. This revealed 2 review articles, 17 case controlled studies, 4 case series and 5 case reports. This review summarises the published literature on mountain biking injuries, discusses injury frequency and common injury mechanisms. Riders are quick to adopt safety measures. Helmet usage is now increasingly common and handlebar adaptations have been discontinued. Although the sport has a reputation for speed and risk with research and awareness, injury prevention measures are being adopted making the sport as safe as possible.

  10. The Olympic Mountains Experiment (OLYMPEX)

    Energy Technology Data Exchange (ETDEWEB)

    Houze, Robert A. [University of Washington, Seattle, Washington; Pacific Northwest National Laboratory, Richland, Washington; McMurdie, Lynn A. [University of Washington, Seattle, Washington; Petersen, Walter A. [NASA Marshall Space Flight Center, Huntsville, Alabama; Schwaller, Mathew R. [NASA Goddard Space Flight Center, Greenbelt, Maryland; Baccus, William [Olympic National Park, Port Angeles, Washington; Lundquist, Jessica D. [University of Washington, Seattle, Washington; Mass, Clifford F. [University of Washington, Seattle, Washington; Nijssen, Bart [University of Washington, Seattle, Washington; Rutledge, Steven A. [Colorado State University, Fort Collins, Colorado; Hudak, David R. [Environment and Climate Change Canada, King City, Ontario, Canada; Tanelli, Simone [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California; Mace, Gerald G. [University of Utah, Salt Lake City, Utah; Poellot, Michael R. [University of North Dakota, Grand Forks, North Dakota; Lettenmaier, Dennis P. [University of California, Los Angeles, Los Angeles, California; Zagrodnik, Joseph P. [University of Washington, Seattle, Washington; Rowe, Angela K. [University of Washington, Seattle, Washington; DeHart, Jennifer C. [University of Washington, Seattle, Washington; Madaus, Luke E. [National Center for Atmospheric Research, Boulder, Colorado; Barnes, Hannah C. [Pacific Northwest National Laboratory, Richland, Washington

    2017-10-01

    the Olympic Mountains Experiment (OLYMPEX) took place during the 2015-2016 fall-winter season in the vicinity of the mountainous Olympic Peninsula of Washington State. The goals of OLYMPEX were to provide physical and hydrologic ground validation for the U.S./Japan Global Precipitation Measurement (GPM) satellite mission and, more specifically, to study how precipitation in Pacific frontal systems is modified by passage over coastal mountains. Four transportable scanning dual-polarization Doppler radars of various wavelengths were installed. Surface stations were placed at various altitudes to measure precipitation rates, particle size distributions, and fall velocities. Autonomous recording cameras monitored and recorded snow accumulation. Four research aircraft supplied by NASA investigated precipitation processes and snow cover, and supplemental rawinsondes and dropsondes were deployed during precipitation events. Numerous Pacific frontal systems were sampled, including several reaching "atmospheric river" status, warm and cold frontal systems, and postfrontal convection

  11. Yucca Mountain project prototype testing

    International Nuclear Information System (INIS)

    Hughes, W.T.; Girdley, W.A.

    1990-01-01

    The U.S. DOE is responsible for characterizing the Yucca Mountain site in Nevada to determine its suitability for development as a geologic repository to isolate high-level nuclear waste for at least 10,000 years. This unprecedented task relies in part on measurements made with relatively new methods or applications, such as dry coring and overcoring for studies to be conducted from the land surface and in an underground facility. The Yucca Mountain Project has, since 1988, implemented a program of equipment development and methods development for a broad spectrum of hydrologic, geologic, rock mechanics, and thermomechanical tests planned for use in an Exploratory Shaft during site characterization at the Yucca Mountain site. A second major program was fielded beginning in April 1989 to develop and test methods and equipment for surface drilling to obtain core samples from depth using only air as a circulating medium. The third major area of prototype testing has been during the ongoing development of the Instrumentation/ Data Acquisition System (IDAS), designed to collect and monitor data from down-hole instrumentation in the unsaturated zone, and store and transmit the data to a central archiving computer. Future prototype work is planned for several programs including the application of vertical seismic profiling methods and flume design to characterizing the geology at Yucca Mountain. The major objectives of this prototype testing are to assure that planned Site Characterization testing can be carried out effectively at Yucca Mountain, both in the Exploratory Shaft Facility (ESF), and from the surface, and to avoid potential major failures or delays that could result from the need to re-design testing concepts or equipment. This paper will describe the scope of the Yucca Mountain Project prototype testing programs and summarize results to date. 3 figs

  12. Glaciation of alpine valleys: The glacier - debris-covered glacier - rock glacier continuum

    Science.gov (United States)

    Anderson, Robert S.; Anderson, Leif S.; Armstrong, William H.; Rossi, Matthew W.; Crump, Sarah E.

    2018-06-01

    Alpine ice varies from pure ice glaciers to partially debris-covered glaciers to rock glaciers, as defined by the degree of debris cover. In many low- to mid-latitude mountain ranges, the few bare ice glaciers that do exist in the present climate are small and are found where snow is focused by avalanches and where direct exposure to radiation is minimized. Instead, valley heads are more likely to be populated by rock glaciers, which can number in the hundreds. These rock-cloaked glaciers represent some of the most identifiable components of the cryosphere today in low- to mid-latitude settings, and the over-steepened snouts pose an often overlooked hazard to travel in alpine terrain. Geomorphically, rock glaciers serve as conveyor belts atop which rock is pulled away from the base of cliffs. In this work, we show how rock glaciers can be treated as an end-member case that is captured in numerical models of glaciers that include ice dynamics, debris dynamics, and the feedbacks between them. Specifically, we focus on the transition from debris-covered glaciers, where the modern equilibrium line altitude (ELA) intersects the topography, to rock glaciers, where the modern ELA lies above the topography. On debris-covered glaciers (i.e., glaciers with a partial rock mantle), rock delivered to the glacier from its headwall, or from sidewall debris swept into the glacier at tributary junctions, travels englacially to emerge below the ELA. There it accumulates on the surface and damps the rate of melt of underlying ice. This allows the termini of debris-covered glaciers to extend beyond debris-free counterparts, thereby decreasing the ratio of accumulation area to total area of the glacier (AAR). In contrast, rock glaciers (i.e., glaciers with a full rock mantle) occur where and when the environmental ELA rises above the topography. They require avalanches and rockfall from steep headwalls. The occurrence of rock glaciers reflects this dependence on avalanche sources

  13. Mountain Warfare: The Need for Specialist Training

    National Research Council Canada - National Science Library

    Malik, Muhammad

    2003-01-01

    This study focuses on the need for specialist training for mountain warfare. It analyzes the special characteristics of mountain and high altitude terrain which affect conduct of military operations...

  14. New U-Pb age constraints on the upper Banxi Group and synchrony of the Sturtian glaciation in South China

    Directory of Open Access Journals (Sweden)

    Gaoyuan Song

    2017-09-01

    -Sturtian strata in Oman and Canada. These ages indicate that the Jiangkou (Sturtian glaciation in South China started at ca. 715 Ma instead of ca. 780 Ma and support a globally synchronous initiation of the Sturtian glaciation at ca. 715 Ma.

  15. A mountain of millipedes I

    DEFF Research Database (Denmark)

    Enghoff, Henrik

    2014-01-01

    Twenty new species of the millipede genus Chaleponcus Attems, 1914, are described from the Udzungwa Mountains: C. netus sp. nov., C. quasimodo sp. nov., C. malleolus sp. nov., C. scopus sp. nov., C. nikolajscharffi sp. nov., C. mwanihanensis sp. nov., C. basiliscus sp. nov., C. krai sp. nov., C...

  16. Soil variability in mountain areas

    OpenAIRE

    Zanini, E.; Freppaz, M.; Stanchi, S.; Bonifacio, E.; Egli, M.

    2015-01-01

    The high spatial variability of soils is a relevant issue at local and global scales, and determines the complexity of soil ecosystem functions and services. This variability derives from strong dependencies of soil ecosystems on parent materials, climate, relief and biosphere, including human impact. Although present in all environments, the interactions of soils with these forming factors are particularly striking in mountain areas.

  17. The Mountaineer-Malaysia Connection.

    Science.gov (United States)

    Young, Jeff

    1997-01-01

    A 26-day summer field course of West Virginia University's (WVU) Recreation and Parks Department took students to Malaysia's mountains and rainforests to observe how Malaysians are managing national parks, problem elephants, and population pressures on parks. The adventure provided powerful learning experiences. Further exchanges between WVU and…

  18. A mountain of millipedes V

    DEFF Research Database (Denmark)

    Enghoff, Henrik

    2016-01-01

    Three new genera of Odontopygidae are described, all based on new species from the Udzungwa mountains, Tanzania, and all monotypic: Casuariverpa gen. nov. (type species: C. scarpa gen. et sp. nov.), Yia gen. nov. (type species: Y. geminispina gen. et sp. nov.), and Utiliverpa gen. nov. (type spec...

  19. Mountain biking injuries: an update.

    Science.gov (United States)

    Kronisch, Robert L; Pfeiffer, Ronald P

    2002-01-01

    This article reviews the available literature regarding injuries in off-road bicyclists. Recent progress in injury research has allowed the description of several patterns of injury in this sport. Mountain biking remains popular, particularly among young males, although sales and participation figures have decreased in the last several years. Competition in downhill racing has increased, while cross-country racing has decreased somewhat in popularity. Recreational riders comprise the largest segment of participants, but little is known about the demographics and injury epidemiology of noncompetitive mountain cyclists. Most mountain bikers participating in surveys reported a history of previous injuries, but prospective studies conducted at mountain bike races have found injury rates of bike racing the risk of injury may be higher for women than men. Minor injuries such as abrasions and contusions occur frequently, but are usually of little consequence. Fractures usually involve the torso or upper extremities, and shoulder injuries are common. Head and face injuries are not always prevented by current helmet designs. Fatal injuries are rare but have been reported. Improvements in safety equipment, rider training and racecourse design are suggested injury prevention measures. The authors encourage continued research in this sport.

  20. Gearing Up for Mountain Biking.

    Science.gov (United States)

    Jahnke, Thomas; Hamson, Mike

    1999-01-01

    Examines the gear system of a mountain bike to discover any redundancy in the many gear settings available to the cyclist. Suggests a best strategy for changing up through the gears on a typical 21-gear system and an adjustment to the available gears that would result in a smoother change. (Author/ASK)

  1. A mountain of millipedes III

    DEFF Research Database (Denmark)

    Enghoff, Henrik

    2016-01-01

    The new genus Geotypodon gen. nov. is described. It includes two species from the Udzungwa Mountains: G. millemanus gen. et sp. nov. (type species) and G. submontanus gen. et sp. nov., one species from nearby Iringa: G. iringensis gen. et sp. nov., and 18 previously described species hitherto...

  2. Rocky Mountain spotted fever, Panama.

    Science.gov (United States)

    Estripeaut, Dora; Aramburú, María Gabriela; Sáez-Llorens, Xavier; Thompson, Herbert A; Dasch, Gregory A; Paddock, Christopher D; Zaki, Sherif; Eremeeva, Marina E

    2007-11-01

    We describe a fatal pediatric case of Rocky Mountain spotted fever in Panama, the first, to our knowledge, since the 1950s. Diagnosis was established by immunohistochemistry, PCR, and isolation of Rickettsia rickettsii from postmortem tissues. Molecular typing demonstrated strong relatedness of the isolate to strains of R. rickettsii from Central and South America.

  3. Rocky Mountain spotted fever, Colombia.

    Science.gov (United States)

    Hidalgo, Marylin; Orejuela, Leonora; Fuya, Patricia; Carrillo, Pilar; Hernandez, Jorge; Parra, Edgar; Keng, Colette; Small, Melissa; Olano, Juan P; Bouyer, Donald; Castaneda, Elizabeth; Walker, David; Valbuena, Gustavo

    2007-07-01

    We investigated 2 fatal cases of Rocky Mountain spotted fever that occurred in 2003 and 2004 near the same locality in Colombia where the disease was first reported in the 1930s. A retrospective serosurvey of febrile patients showed that > 21% of the serum samples had antibodies aaainst spotted fever group rickettsiae.

  4. Lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, investigated using optically stimulated luminescence dating of beach ridges

    International Nuclear Information System (INIS)

    Li Dewen; Li Yingkui; Ma Baoqi; Zhao, Junxiang; Dong Guocheng; Wang Liqiang

    2009-01-01

    This paper presents a preliminary study on lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, by dating four groups of beach ridges using optically stimulated luminescence (OSL). The highest/oldest beach ridge group (>100 m higher than the current lake level) is dated back to 67.9 ± 2.4 ka BP, corresponding to the early stage of the Last Glaciation (marine isotope stage (MIS) 4). This date further supports that no plateau-scale ice sheet covered the Tibetan Plateau during the Last Glaciation. The other three groups produce OSL ages of 30.4 ± 2.9 to 18.6 ± 1.7, 12.5 ± 1.6 to 9.2 ± 0.5, and 6.9 ± 0.2 ka BP respectively, most likely corresponding to cold or wet climate periods of the late stage of the Last Glaciation (MIS 2), deglaciation, and Holocene Hypsithermal. On the plateau scale, these four beach ridge groups are almost synchronous with advances or standstills of Himalayan glaciers, indicating similar climate controls across the central and southern Tibetan Plateau, and being consistent with the conclusion, obtained from nearby ice core records, that this area is affected by the South Asia monsoon. Furthermore, beach ridges are also synchronous with fluvial terraces in the northern Tibetan Plateau, implying common driving forces during their formation. Therefore, some terraces may be formed as a result of climate events rather than being of tectonic origin.

  5. Mass balance and sliding velocity of the Puget lobe of the cordilleran ice sheet during the last glaciation

    Science.gov (United States)

    Booth, D.B.

    1986-01-01

    An estimate of the sliding velocity and basal meltwater discharge of the Puget lobe of the Cordilleran ice sheet can be calculated from its reconstructed extent, altitude, and mass balance. Lobe dimensions and surface altitudes are inferred from ice limits and flow-direction indicators. Net annual mass balance and total ablation are calculated from relations empirically derived from modern maritime glaciers. An equilibrium-line altitude between 1200 and 1250 m is calculated for the maximum glacial advance (ca. 15,000 yr B.P.) during the Vashon Stade of the Fraser Glaciation. This estimate is in accord with geologic data and is insensitive to plausible variability in the parameters used in the reconstruction. Resultant sliding velocities are as much as 650 m/a at the equilibrium line, decreasing both up- and downglacier. Such velocities for an ice sheet of this size are consistent with nonsurging behavior. Average meltwater discharge increases monotonically downglacier to 3000 m3/sec at the terminus and is of a comparable magnitude to ice discharge over much of the glacier's ablation area. Palcoclimatic inferences derived from this reconstruction are consistent with previous, independently derived studies of late Pleistocene temperature and precipitation in the Pacific Northwest. ?? 1986.

  6. Munroa argentina, a Grass of the South American Transition Zone, Survived the Andean Uplift, Aridification and Glaciations of the Quaternary

    Science.gov (United States)

    Amarilla, Leonardo D.; Anton, Ana M.; Chiapella, Jorge O.; Manifesto, María M.; Angulo, Diego F.; Sosa, Victoria

    2015-01-01

    The South American Transition Zone (SATZ) is a biogeographic area in which not only orogeny (Andes uplift) and climate events (aridification) since the mid-Miocene, but also Quaternary glaciation cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species’ range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2–1.2) Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity. PMID:26110533

  7. Munroa argentina, a Grass of the South American Transition Zone, Survived the Andean Uplift, Aridification and Glaciations of the Quaternary.

    Directory of Open Access Journals (Sweden)

    Leonardo D Amarilla

    Full Text Available The South American Transition Zone (SATZ is a biogeographic area in which not only orogeny (Andes uplift and climate events (aridification since the mid-Miocene, but also Quaternary glaciation cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species' range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2-1.2 Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity.

  8. Quaternary glaciation and hydrologic variation in the South American tropics as reconstructed from the Lake Titicaca drilling project

    Science.gov (United States)

    Fritz, Sherilyn C.; Baker, Paul A.; Seltzer, Geoffrey O.; Ballantyne, Ashley; Tapia, Pedro; Cheng, Hai; Edwards, R. Lawrence

    2007-11-01

    A 136-m-long drill core of sediments was recovered from tropical high-altitude Lake Titicaca, Bolivia-Peru, enabling a reconstruction of past climate that spans four cycles of regional glacial advance and retreat and that is estimated to extend continuously over the last 370,000 yr. Within the errors of the age model, the periods of regional glacial advance and retreat are concordant respectively with global glacial and interglacial stages. Periods of ice advance in the southern tropical Andes generally were periods of positive water balance, as evidenced by deeper and fresher conditions in Lake Titicaca. Conversely, reduced glaciation occurred during periods of negative water balance and shallow closed-basin conditions in the lake. The apparent coincidence of positive water balance of Lake Titicaca and glacial growth in the adjacent Andes with Northern Hemisphere ice sheet expansion implies that regional water balance and glacial mass balance are strongly influenced by global-scale temperature changes, as well as by precessional forcing of the South American summer monsoon.

  9. Moraine preservation and boulder erosion in the tropical Andes: interpreting old surface exposure ages in glaciated valleys

    Science.gov (United States)

    Smith, Jacqueline A.; Finkel, Robert C.; Farber, Daniel L.; Rodbell, Donald T.; Seltzer, Geoffrey O.

    2005-10-01

    Cosmogenic dating provides a long-awaited means of directly dating glacial deposits that pre-date the last glacial cycle. Although the potential benefits of longer chronologies are obvious, the greater uncertainty associated with older cosmogenic ages may be less readily apparent. We illustrate the challenges of developing and interpreting a long chronology using our data from the Peruvian Andes. We used surface exposure dating with cosmogenic radionuclides (CRNs; 10Be and 26Al) to date 140 boulders on moraines in valleys bordering the Junin Plain (11° S, 76° W) in central Peru. Our chronology spans multiple glacial cycles and includes exposure ages greater than 1 million years, which indicate that long-term rates of boulder erosion have been very low. Interpreting the chronology of moraines for glaciations that predate the last glacial cycle is complicated by the need to consider boulder erosion and exhumation, surface uplift, and inheritance of CRNs from previous exposure intervals. As an example, we recalculate exposure ages using our boulder erosion rates (0.3-0.5 metres per million years) and estimated surface uplift rates to emphasise both the challenges involved in interpreting old surface exposure ages and the value of chronological data, even with large uncertainties, when reconstructing the palaeoclimate of a region.

  10. Munroa argentina, a Grass of the South American Transition Zone, Survived the Andean Uplift, Aridification and Glaciations of the Quaternary.

    Science.gov (United States)

    Amarilla, Leonardo D; Anton, Ana M; Chiapella, Jorge O; Manifesto, María M; Angulo, Diego F; Sosa, Victoria

    2015-01-01

    The South American Transition Zone (SATZ) is a biogeographic area in which not only orogeny (Andes uplift) and climate events (aridification) since the mid-Miocene, but also Quaternary glaciation cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species' range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2-1.2) Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity.

  11. Lithologic influences on groundwater recharge through incised glacial till from profile to regional scales: Evidence from glaciated Eastern Nebraska

    Science.gov (United States)

    Gates, John B.; Steele, Gregory V.; Nasta, Paolo; Szilagyi, Jozsef

    2014-01-01

    Variability in sediment hydraulic properties associated with landscape depositional and erosional features can influence groundwater recharge processes by affecting soil-water storage and transmission. This study considers recharge to aquifers underlying river-incised glaciated terrain where the distribution of clay-rich till is largely intact in upland locations but has been removed by alluvial erosion in stream valleys. In a stream-dissected glacial region in eastern Nebraska (Great Plains region of the United States), recharge estimates were developed for nested profile, aquifer, and regional scales using unsaturated zone profile measurements (matric potentials, Cl- and 3H), groundwater tracers (CFC-12 and SF6), and a remote sensing-assisted water balance model. Results show a consistent influence of till lithology on recharge rates across nested spatial scales despite substantial uncertainty in all recharge estimation methods, suggesting that minimal diffuse recharge occurs through upland glacial till lithology whereas diffuse recharge occurs in river valleys where till is locally absent. Diffuse recharge is estimated to account for a maximum of 61% of total recharge based on comparison of diffuse recharge estimated from the unsaturated zone (0-43 mm yr-1) and total recharge estimated from groundwater tracers (median 58 mm yr-1) and water balance modeling (median 56 mm yr-1). The results underscore the importance of lithologic controls on the distributions of both recharge rates and mechanisms.

  12. Producing an integrated climate-land-energy-water (CLEW) model for glaciated regions in the developing world

    Science.gov (United States)

    Delman, E. M.; Thomas, B. F.; Famiglietti, J. S.

    2013-12-01

    Growing concern over the impact of climate change on global freshwater resources has spurred a demand for practical, basin-specific adaptation tools. The potential for water stress is particularly inflated in the glaciated watersheds of the developing world; widespread and rapid glacial retreat has forced regional resource managers to reconcile the reality of a diminishing supply with an overall increase in demand, while accounting for the underlying geopolitical and cultural context. An integrated approach, such as the development of a Climate-Land-Energy-Water (CLEW) model that examines relationships among climate, land-use, and the energy and water sectors, can be used to assess the impact of different climate change scenarios on basin sustainability and vulnerability. This study will first constrain the hydrologic budget in the Río Santa Watershed of Peru using satellite imagery, historical and contemporary stream discharge data, hydrologic modeling, climatic data analysis, and isotopic and chemical tracers. Ultimately, glacier retreat will be examined at the watershed scale and be used as an input in the CLEW model framework to assess hydrologic budget scenarios and the subsequent impact on regional economic and environmental sustainability.

  13. Quantification and economic valuation of the capture of CO2 for Eucalyptus plantations, established by the Preca in the carboniferous Basins of Cesar, Cauca Valley, Cauca and Highland Cundiboyacense

    International Nuclear Information System (INIS)

    Diaz Fonseca, Sandra Ximena; Molano Morales, Miguel Angel

    2001-01-01

    This study, as first measure it looks for to quantify the tons of CO 2 captured by the increment in the biomass of forestall plantations of the Eucalyptus genus established by the PRECA of Ecocarbon in the carboniferous basins of the Cesar, Cauca Valley, Cauca and Highland Cundiboyacense and in second measure to determine the economic value that the sale of this environmental service can represent for a developing country as Colombia. The results obtained for each one of the plantations in each carboniferous basin are determined, and statistical models that will allow calculating the capture of CO 2 carried out by plantations of three different species of Eucalyptus (E. camaldulensis, e. grandis and E. globulus), starting from the volume in foot of the timber only barked

  14. Quantification and economic valuation of the capture of CO2 for plantations of the Eucalyptus, genus, settled down by the PRECA in the carboniferous basins of Cesar, Cauca Valley, Cauca and Cundiboyacense Highland

    International Nuclear Information System (INIS)

    Diaz F, Sandra Ximena; Molano M, Miguel Angel

    2001-01-01

    In this study, the first measure is to quantify the tons of CO 2 captured by the increment in the biomass of forest plantations of the Eucalyptus genus, settled down by the PRECA of Ecocarbon in the carboniferous basins of the Cesar, Cauca Valley, Cauca and Cundiboyacense highland and in second measure to determine the economic value that the sale of this environmental service can represent for a developing country as Colombia. The results obtained for each one of the plantations settled down in each carboniferous basin are determined and statistical models that will allow to calculate the capture of CO 2 carried out by plantations of three different species of Eucalyptus (E. Camaldulensis, E. grandis and E. globulus)

  15. The stratigraphic imprint of a mid-Telychian (Llandovery, Early Silurian glaciation on far-field shallow-water carbonates, Anticosti Island, Eastern Canada

    Directory of Open Access Journals (Sweden)

    François Clayer

    2014-12-01

    Full Text Available The near-field stratigraphic record of the Early Silurian glaciations is well documented in the literature. Data from far-field areas are, however, sparse. One of the best far-field stratigraphic records of these Llandovery glaciations is exposed on Anticosti Island in eastern Canada. Eight shallow-water paleotropical facies are present close to the mid-Telychian Jupiter–Chicotte formational boundary along the south-central coast of Anticosti Island. These can be grouped into three facies associations that include, from bottom to top: a carbonate facies association (FA-1, a mixed siliciclastic and carbonate facies association (FA-2 and an encrinitic facies association (FA-3. These mid- to outer-ramp strata represent deposition mostly from episodic, high-energy storm events as evidenced by their sharp bases, hummocky cross-stratification, large wave ripples, gutter casts and wave-enhanced sediment gravity flow deposits. Superimposed on a long-term regressive trend, one main transgressive–regressive (TR sequence and four meter-scale TR cycles are evident, indicating a multi-order stratigraphic framework developed under the influence of glacio-eustasy. The Jupiter–Chicotte formational boundary, a regional discontinuity surface caused by a forced regression, corresponds to the onset of a far-field mid-Telychian glaciation.

  16. Continuous Lake-Sediment Records of Glaciation in the Sierra Nevada between 52,600 and 12,500 14C yr B.P

    Science.gov (United States)

    Benson, Larry V.; May, Howard M.; Antweiler, Ronald C.; Brinton, Terry I.; Kashgarian, Michaele; Smoot, Joseph P.; Lund, Steve P.

    1998-09-01

    The chemistry of the carbonate-free clay-size fraction of Owens Lake sediments supports the use of total organic carbon and magnetic susceptibility as indicators of stadial-interstadial oscillations. Owens Lake records of total organic carbon, magnetic susceptibility, and chemical composition of the carbonate-free, clay-size fraction indicate that Tioga glaciation began ˜24,500 and ended by ˜13,600 14C yr B.P. Many of the components of glacial rock flour (e.g., TiO 2, MnO, BaO) found in Owens Lake sediments achieved maximum values during the Tioga glaciation when valley glaciers reached their greatest extent. Total organic carbon and SiO 2(amorphous) concentrations reached minimum values during Tioga glaciation, resulting from decreases in productivity that accompanied the introduction of rock flour into the surface waters of Owens Lake. At least 20 stadial-interstadial oscillations occurred in the Sierra Nevada between 52,600 and 14,000 14C yr B.P. Total organic carbon data from a Pyramid Lake sediment core also indicate oscillations in glacier activity between >39,500 and ˜13,600 14C yr B.P. Alpine glacier oscillations occurred on a frequency of ≤1900 yr in both basins, suggesting that millennial-scale oscillations occurred in California and Nevada during most of the past 52,600 yr.

  17. Changes in mountain glacier systems and the distribution of main climatic parameters on the territory of Russia (second part of the XX -beginning of the XXI century).

    Science.gov (United States)

    Tatiana, K.; Nosenko, G.; Popova, V.; Muraviev, A.; Nikitin, S.; Chernova, L.

    2017-12-01

    Mountain glaciers are vital sources of water worldwide to many densely-populated regions. Most glaciers are now shrinking, resulting in variable water supplies and sustained sea level rise. Rapid glacier change threatens water, energy and food security. Further glacier mass loss is likely in response to recent climate change, driven by global increases in air temperatures and the production of atmospheric pollutants. However, high altitudes and rugged topography generate regional weather systems that complicate the investigation of the relationship between climate and glacier change. Predictive models need to move beyond the state-of-the-art to couple advanced climate models with accurate representations of glacier processes, and more detailed and reliable data describing the state of mountain glaciers are required to constrain these models, both from monitoring individual glaciers and regional remote-sensing observations. Glaciation exists on the territory of Russia for thousands of years. At present both mountain glaciers and continental ice sheets are present there. Continental ice sheets are located on islands and archipelagoes of Russian Arctic region and mountain glaciers are wide-spread on continental part of the country where it currently covers the area of about 3,480,000 km². Now there are 18 mountain glacier regions on the territory of Russia. We present recent data on glaciers state and changes in mountain regions of Russia based on remote sensing and in situ studies and distribution of main climatic parameters that affect the existence of glaciers: summer air temperature, winter precipitations and maximum value of snow thickness. Acknowledgements. This presentation includes the results of research project № 0148-2014-0007 of the Research Plan of the Institute of Geography, RAS and research project supported by the Russian Geographical Society (grant number 05/2017/RGS-RFBR).

  18. A comparative study of detrital zircon ages from river sediment and rocks of the Karoo Supergroup (Late Carboniferous to Jurassic), Eastern Cape Province, South Africa : implications for the tectono-sedimentary evolution of Gondwanaland’s southern continental margin

    OpenAIRE

    2014-01-01

    M.Sc. (Geology) The Mzimvubu River, situated in the Eastern Cape Province of South Africa, drains essentially strata of the Late Carboniferous to Jurassic Karoo Supergroup with minor intersection of the underlying Devonian Msikaba Formation near the mouth of the river at Port St. Johns. Rock- and river sediment samples were collected at specific points from within the Mzimvubu River drainage basin, based on changes in the geology through which the rivers flow. Detrital zircon age populatio...

  19. Carboniferous-Permian tectonic transition envisaged in two magmatic episodes at the Kuruer Cu-Au deposit, Western Tianshan (NW China)

    Science.gov (United States)

    Yu, Jie; Li, Nuo; Qi, Nan; Guo, Jian-Ping; Chen, Yan-Jing

    2018-03-01

    The Western Tianshan in NW China is one of the most important gold provinces in the Central Asian Orogenic Belt (CAOB). The recently discovered Kuruer Cu-Au deposit has been interpreted to represent a transition from high-sulfidation epithermal to porphyry mineralization system. In this study, we present new LA-ICP-MS zircon U-Pb ages for the many magmatic rock types at Kuruer, including the Dahalajunshan Formation andesitic tuff (333.2 ± 1.6 Ma), diorite porphyry (269.7 ± 2.0 Ma), slightly-altered (264.4 ± 2.6 Ma) and intensively-altered (270.5 ± 2.5 Ma) albite porphyry. These ages reveal two distinct magmatic episodes: The Early Carboniferous Dahalajunshan Formation (wall rocks) andesitic tuff samples contain narrow ranges of SiO2 (60.29-61.28 wt.%), TiO2 (0.96-0.98 wt.%), Al2O3 (16.55-16.57 wt.%) and Fe2O3T (5.36-5.57 wt.%). The tuff is characterized by LREE enrichment and HFSE depletion, as well as LREE/HREE enrichment ((La/Yb)N = 8.31-8.76) and negative Eu anomalies (δEu = 0.64-0.76). Zircon εHf (t) values are 5.4-8.2, and two-stage Hf model ages (TDM2) are 821-1016 Ma, indicating partial melting of a moderately depleted mantle wedge with Precambrian continental crustal input. The ore-forming Middle Permian diorite porphyry and (quartz) albite porphyry have variable major oxide compositions (e.g., SiO2 = 53.09-53.12 wt.% for the diorite porphyry, 70.84-78.03 wt.% for the albite porphyry, and 74.07-75.03 wt.% for the quartz albite porphyry) but similar chondrite-normalized REE and primitive mantle-normalized multi-element patterns. These porphyries display LREE enrichment and HFSE depletion, as well as elevated LREE/HREE enrichment and negative Eu anomalies. The positive zircon εHf(t) values (11.7-15.9 for the diorite porphyry, 8.9-14.9 for the albite porphyry) and young two-stage Hf model ages (TDM2) (282-542 Ma for the diorite porphyry, 337-717 Ma for the albite porphyry) indicate a major juvenile continental crustal involvement. We propose that the

  20. Early Silurian to Early Carboniferous ridge subduction in NW Junggar: Evidence from geochronological, geochemical, and Sr-Nd-Hf isotopic data on alkali granites and adakites

    Science.gov (United States)

    Zhang, Chen; Santosh, M.; Liu, Luofu; Luo, Qun; Zhang, Xin; Liu, Dongdong

    2018-02-01

    The Central Asian Orogenic Belt (CAOB) evolved through a long-lived orogeny involving multiple episodes of subduction and accretion marking a major phase of continental growth during the Paleozoic. The northern part of the Western Junggar region (NW Junggar) offers a window into these processes, particularly to constrain the timing of closure of the Paleo-Asian Ocean. Here we report geochemical, geochronological, and isotopic data from K-feldspar granites and adakitic rocks from the NW Junggar region. Zircon U-Pb ages suggest that the granites were emplaced during Early Silurian to the Early Carboniferous (434-328 Ma). The granites show geochemical characteristics similar to those of A-type granites, with high SiO2 (71.13-76.72 wt%), Na2O + K2O (8.00-9.59 wt%), and Al2O3 (12.28-14.08 wt%), but depleted Sr, Nb, Ta and Eu. They display moderate to high positive εNd(t) and εHf(t) values (4.26-8.21 and 7.69-14.60, respectively) and young Nd and Hf model ages (T2DM-Nd = 489-740 Ma and T2DM-Hf = 471-845 Ma), suggesting magma derivation through partial melting of lower crust in the Boshchekul-Chingiz and Zharma-Saur arcs. The adakites are characterized by high Sr content (406.5-751.6 ppm), and low Y (13.8-16.4 ppm) and Yb (1.5-1.8 ppm) content, yielding relatively high Sr/Y ratios (25.38-49.41) similar to those of modern adakites. They have high positive εNd(t) and εHf(t) values (7.85-8.25 and 13.23-15.97, respectively) and young Nd and Hf model ages (T2DM-Nd = 429-535 Ma and T2DM-Hf = 355-550 Ma), indicating that their source magmas were likely derived from partial melting of the oceanic crust beneath the Boshchekul-Chingiz arc. The petrogenesis and distribution of the A-type granites and adakites, as well as the tectonic architecture of the region, suggest that a ridge subduction event might have occurred during the Early Silurian to Early Carboniferous. In combination with previous studies in the Chinese Altai, we suggest a two-sided ridge subduction model for the

  1. Geomechanical characterization of the Upper Carboniferous under thermal stress for the evaluation of a High Temperature - Mine Thermal Energy Storage (HT-MTES)

    Science.gov (United States)

    Hahn, Florian; Brüggemann, Nina; Bracke, Rolf; Alber, Michael

    2017-04-01

    The goal of this R&D project is to create a technically and economically feasible conceptual model for a High Temperature - Mine Thermal Energy Storage (HT-MTES) for the energetic reuse of a mine on the example of the Prosper-Haniel coal mine in Bottrop, Germany. This project is funded by the "Initiative Energy Storage" program of the German Federal Ministries BMWi, BMU and BMBF. At the end of 2018, the last operative coal mine in North Rhine-Westphalia, Germany (Prosper-Haniel), is going to be closed down, plugged and abandoned. Large amounts of subsurface infrastructures, resembled mainly by open parts of former galleries and mining faces are going to be flooded, after the mine is closed down and therefore have the potential to become an enormous geothermal reservoir for a seasonal heat storage. During the summer non-used (waste) heat from solar thermal power plants, garbage incineration, combined heat and power plants (CHP) or industrial production processes can be stored within dedicated drifts of the mine. During the winter season, this surplus heat can be extracted and directly utilized in commercial and/or residential areas. For the evaluation of such a HT-MTES within a former coal mine, the corresponding geomechanical parameters of the Upper Carboniferous under thermal stress needs to be evaluated. Therefore the main rock types of the Upper Carboniferous (claystone, siltstone and sandstone) are subject to a geomechanical characterization before and after thermal cyclic loadings of temperatures up to 200 °C. The samples have been collected directly from the coal mine Prosper-Haniel within a depth range of 1000 - 1200 m. Unconfined compressive and tensile strengths, as well as triaxial tests were performed at room temperature. Furthermore, a range of petrophysical properties like density, thin-section analysis and P-wave velocities were determined. First results show an indication that the overall strength properties of the samples are not effected by

  2. Characterising the hydrothermal circulation patterns beneath thermal springs in the limestones of the Carboniferous Dublin Basin, Ireland: a geophysical and geochemical approach.

    Science.gov (United States)

    Blake, Sarah; Henry, Tiernan; Muller, Mark R.; Jones, Alan G.; Moore, John Paul; Murray, John; Campanyà, Joan; Vozár, Jan; Walsh, John; Rath, Volker

    2016-04-01

    A hydrogeological conceptual model of the sources, circulation pathways and temporal variations of two low-enthalpy thermal springs is derived from a multi-disciplinary approach. The springs are situated in the Carboniferous limestones of the Dublin Basin, in east-central Ireland. Kilbrook spring (Co. Kildare) has the highest recorded temperatures for any thermal spring in Ireland (maximum of 25.0 °C), and St. Gorman's Well (Co. Meath) has a complex and variable temperature profile (maximum of 21.8 °C). These temperatures are elevated with respect to average Irish groundwater temperatures (9.5 - 10.5 °C), and represent a geothermal energy potential, which is currently under evaluation. A multi-disciplinary investigation based upon audio-magnetotelluric (AMT) surveys, time-lapse temperature and chemistry measurements, and hydrochemical analysis, has been undertaken with the aims of investigating the provenance of the thermal groundwater and characterising the geological structures facilitating groundwater circulation in the bedrock. The hydrochemical analysis indicates that the thermal waters flow within the limestones of the Dublin Basin, and there is evidence that Kilbrook spring receives a contribution from deep-basinal fluids. The time-lapse temperature, electrical conductivity and water level records for St. Gorman's Well indicate a strongly non-linear response to recharge inputs to the system, suggestive of fluid flow in karst conduits. The 3-D electrical resistivity models of the subsurface revealed two types of geological structure beneath the springs; (1) Carboniferous normal faults, and (2) Cenozoic strike-slip faults. These structures are dissolutionally enhanced, particularly where they intersect. The karstification of these structures, which extend to depths of at least 500 m, has provided conduits that facilitate the operation of a relatively deep hydrothermal circulation pattern (likely estimated depths between 240 and 1,000 m) within the Dublin

  3. Spiders in mountain habitats of the Giant Mountains

    Czech Academy of Sciences Publication Activity Database

    Růžička, Vlastimil; Vaněk, J.; Šmilauer, P.

    2012-01-01

    Roč. 43, č. 4 (2012), s. 341-347 ISSN 1067-4136 Institutional research plan: CEZ:AV0Z50070508 Keywords : Giant Mountains (Krkonoše, Karkonosze) * spider s * anemo-orographic systems Subject RIV: EH - Ecology, Behaviour Impact factor: 0.236, year: 2012 http://www.springerlink.com/content/0k5g721q1155r146/fulltext.pdf

  4. Microbial activity at Yucca Mountain

    International Nuclear Information System (INIS)

    Horn, J.M.; Meike, A.

    1995-01-01

    The U.S. Department of Energy is engaged in a suitability study for a potential geological repository at Yucca Mountain, Nevada, for the containment and storage of commercially generated spent fuel and defense high-level nuclear waste. There is growing recognition of the role that biotic factors could play in this repository, either directly through microbially induced corrosion (MIC), or indirectly by altering the chemical environment or contributing to the transport of radionuclides. As a first step toward describing and predicting these processes, a workshop was held on April 10-12, 1995, in Lafayette, California. The immediate aims of the workshop were: (1) To identify microbially related processes relevant to the design of a radioactive waste repository under conditions similar to those at Yucca Mountain. (2) To determine parameters that are critical to the evaluation of a disturbed subterranean environment. (3) To define the most effective means of investigating the factors thus identified

  5. Microbial activity at Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    Horn, J.M.; Meike, A.

    1995-09-25

    The U.S. Department of Energy is engaged in a suitability study for a potential geological repository at Yucca Mountain, Nevada, for the containment and storage of commercially generated spent fuel and defense high-level nuclear waste. There is growing recognition of the role that biotic factors could play in this repository, either directly through microbially induced corrosion (MIC), or indirectly by altering the chemical environment or contributing to the transport of radionuclides. As a first step toward describing and predicting these processes, a workshop was held on April 10-12, 1995, in Lafayette, California. The immediate aims of the workshop were: (1) To identify microbially related processes relevant to the design of a radioactive waste repository under conditions similar to those at Yucca Mountain. (2) To determine parameters that are critical to the evaluation of a disturbed subterranean environment. (3) To define the most effective means of investigating the factors thus identified.

  6. Managing Rocky Mountain spotted fever.

    Science.gov (United States)

    Minniear, Timothy D; Buckingham, Steven C

    2009-11-01

    Rocky Mountain spotted fever is caused by the tick-borne bacterium Rickettsia rickettsii. Symptoms range from moderate illness to severe illness, including cardiovascular compromise, coma and death. The disease is prevalent in most of the USA, especially during warmer months. The trademark presentation is fever and rash with a history of tick bite, although tick exposure is unappreciated in over a third of cases. Other signature symptoms include headache and abdominal pain. The antibiotic therapy of choice for R. rickettsii infection is doxycycline. Preventive measures for Rocky Mountain spotted fever and other tick-borne diseases include: wearing long-sleeved, light colored clothing; checking for tick attachment and removing attached ticks promptly; applying topical insect repellent; and treating clothing with permethrin.

  7. The physiology of mountain biking.

    Science.gov (United States)

    Impellizzeri, Franco M; Marcora, Samuele M

    2007-01-01

    Mountain biking is a popular outdoor recreational activity and an Olympic sport. Cross-country circuit races have a winning time of approximately equal 120 minutes and are performed at an average heart rate close to 90% of the maximum, corresponding to 84% of maximum oxygen uptake (VO2max). More than 80% of race time is spent above the lactate threshold. This very high exercise intensity is related to the fast starting phase of the race; the several climbs, forcing off-road cyclists to expend most of their effort going against gravity; greater rolling resistance; and the isometric contractions of arm and leg muscles necessary for bike handling and stabilisation. Because of the high power output (up to 500W) required during steep climbing and at the start of the race, anaerobic energy metabolism is also likely to be a factor of off-road cycling and deserves further investigation. Mountain bikers' physiological characteristics indicate that aerobic power (VO2max >70 mL/kg/min) and the ability to sustain high work rates for prolonged periods of time are prerequisites for competing at a high level in off-road cycling events. The anthropometric characteristics of mountain bikers are similar to climbers and all-terrain road cyclists. Various parameters of aerobic fitness are correlated to cross-country performance, suggesting that these tests are valid for the physiological assessment of competitive mountain bikers, especially when normalised to body mass. Factors other than aerobic power and capacity might influence off-road cycling performance and require further investigation. These include off-road cycling economy, anaerobic power and capacity, technical ability and pre-exercise nutritional strategies.

  8. Timing of Pleistocene glaciations in the High Atlas, Morocco: New 10Be and 36Cl exposure ages

    Science.gov (United States)

    Hughes, Philip D.; Fink, David; Rodés, Ángel; Fenton, Cassandra R.; Fujioka, Toshiyuki

    2018-01-01

    This paper presents data from 42 new samples yielding Late Pleistocene cosmogenic 10Be and 36Cl exposure ages of moraine boulders across a series of glaciated valleys in the Toubkal Massif (4167 m a.s.l.), High Atlas, Morocco. This represents the first comprehensive Pleistocene glacial chronology in North Africa and one of the largest datasets from the Mediterranean region. The timing of these glacier advances has major implications for understanding the influence of Atlantic depressions on moisture supply to North Africa and the Mediterranean basin during the Pleistocene. The oldest and lowest moraines which span elevations from ∼1900 to 2400 m a.s.l. indicate that the maximum glacier advance occurred from MIS 5 to 3 with a combined mean 10Be and 36Cl age of 50.2 ± 19.5 ka (1 SD; n = 12, 7 outliers). The next moraine units up-valley at higher elevations (∼2200-2600 m a.s.l.) yielded exposure ages close to the global Last Glacial Maximum (LGM) with a combined mean 10Be and 36Cl age of 22.0 ± 4.9 ka (1 SD; n = 9, 7 outliers). The youngest exposure ages are from moraines that were emplaced during the Younger Dryas with a combined mean 10Be and 36Cl age of 12.3 ± 0.9 ka (1 SD; n = 7, no outliers) and are found in cirques at the highest elevations ranging from ∼2900 to 3300 m a.s.l. From moraines predating the Younger Dryas, a large number of young outliers are spread evenly between 6 and 13 ka suggesting a continuing process of exhumation or repositioning of boulders during the early to mid-Holocene. This attests to active seismic processes and possibly intense erosion during this period.

  9. Texture and geochemistry of surface horizons of Arctic soils from a non-glaciated catchment, SW Spitsbergen

    Directory of Open Access Journals (Sweden)

    Szymański Wojciech

    2016-09-01

    Full Text Available Physical and chemical properties of Arctic soils and especially the properties of surface horizons of the soils are very important because they are responsible for the rate and character of plant colonization, development of vegetation cover, and influence the rate and depth of thawing of soils and development of active layer of permafrost during summer. The main aim of the present study is to determine and explain the spatial diversity of selected physical and chemical properties of surface horizons of Arctic soils from the non-glaciated Fuglebekken catchment located in the Hornsund area (SW Spitsbergen by means of geostatistical approach. Results indicate that soil surface horizons in the Fuglebekken catchment are characterized by highly variable physical and chemical properties due to a heterogeneous parent material (marine sediments, moraine, rock debris, tundra vegetation types, and non-uniform influence of seabirds. Soils experiencing the strongest influence of seabird guano have a lower pH than other soils. Soils developed on the lateral moraine of the Hansbreen glacier have the highest pH due to the presence of carbonates in the parent material and a lack or presence of a poorly developed and discontinuous A horizon. The soil surface horizons along the coast of the Hornsund exhibit the highest content of the sand fraction and SiO2. The surface of soils occurring at the foot of the slope of Ariekammen Ridge is characterized by the highest content of silt and clay fractions as well as Al2O3, Fe2O3, and K2O. Soils in the central part of the Fuglebekken catchment are depleted in CaO, MgO, and Na2O in comparison with soils in the other sampling sites, which indicates the highest rate of leaching in this part of the catchment.

  10. Mountain Plant Community Sentinels: AWOL

    Science.gov (United States)

    Malanson, G. P.

    2017-12-01

    Mountain plant communities are thought to be sensitive to climate change. Because climatic gradients are steep on mountain slopes, the spatial response of plant communities to climate change should be compressed and easier to detect. These expectations have led to identifying mountain plant communities as sentinels for climate change. This idea has, however, been criticized. Two critiques, for alpine treeline and alpine tundra, are rehearsed and supplemented. The critique of alpine treeline as sentinel is bolstered with new model results on the confounding role of dispersal mechanisms and sensitivity to climatic volatility. In alpine tundra, for which background turnover rates have yet to be established, community composition may reflect environmental gradients only for extremes where effects of climate are most indirect. Both plant communities, while primarily determined by energy at broad scales, may respond to water as a proximate driver at local scales. These plant communities may not be in equilibrium with climate, and differently scaled time lags may mean that ongoing vegetation change may not signal ongoing climate change (or lack thereof). In both cases a double-whammy is created by scale dependence for time lags and for drivers leading to confusion, but these cases present opportunities for insights into basic ecology.

  11. New archaeorthopteran insects from the Late Carboniferous of the Nord and Pas-de-Calais basins in northern France (Insecta: Cnemidolestodea, Panorthoptera).

    Science.gov (United States)

    Coty, David; Háva, Jiří; Prokop, Jakub; Roques, Patrick; Nel, André

    2014-10-29

    New polyneopteran insects are described from Pennsylvanian (Bashkirian, Moscovian) compressed fossils from the North of France (Insecta: Archaeorthoptera). Discovery of wing apex with distinct venation, e.g., apical fusion of RA with RP, numerous parallel posterior branches of RP with transversal crossveins, can be assigned to cf. Tococladus sp. (Cnemidolestodea: Tococladidae). It represents the second record of Cnemidolestodea from the Avion locality apart from Aviocladus pectinatus Prokop et al., 2014. Bruaylogus magnificus gen. et sp. nov., based on forewing venation, is attributed to Panorthoptera nec Orthoptera having some distinct characters for the placement either close to Oedischiidae or a more basal position possibly with affinities to genus Heterologus. Aviologus duquesnei gen. et sp. nov., based on forewing venation, differs from Oedischiidae by the presence of basal fork of M far from point of separation between M and Cu and fusion of MA with first posterior branch of RP. Aviologus share a long stem of M and simple CuPaβ with Heterologus duyiwuer and H. langfordorum, but both differ in well separated median and radial veins. These new fossils demonstrate that the archaeorthopterid insect fauna from the North of France was rather diverse with links to late Carboniferous and early Permian assemblages in Euramerica such as the Mazon Creek, Carbondale Formation or Elmo, Wellington Formation (Illinois, Kansas, USA) entomofaunas.

  12. Evaluation of the carboniferous resources of the sectors El Jupal, El Carmen y Guayabal. Zone Chinavita, Umbita, Tibana, Department of Boyaca

    International Nuclear Information System (INIS)

    Mejia, Luis Jorge; Pulido Gonzalez, Orlando

    1985-01-01

    The area of the sub-project Chinavita-Umbita-Tibana, located in the Southwest part of the Department of Boyaca was object of a geologic exploration with the purpose of evaluating its carboniferous resources. It was defined an stratigraphic interval of 250 m denominated, middle member from the Guaduas Formation of Maestrichtian to Paleocene age; in which they were determined until 9 coal layers, that were recognized total or partially in 7 chosen sectors during the exploration stage. In them it was made the quantification of the resources and the determination of the physical-chemical characteristics of the coal. The results of 4 of these denominated, El Arenal, Quina, Chiguata and Sisa sectors, they were presented in previous reports. In this report the 3 remaining, denominated El Jupal, El Carmen and Guayabal sectors are studied. The certain coal is bituminous high volatile, capable for thermal use and their importance are in the use that can be given inside the plan of national electrification, of the future amplifications of the thermoelectric of Paipa or Zipaquira. Keeping in mind that resources of the order of 148 million tons were calculated with a power heating average of 6.000 kcal/kg. It is possible to planning a new thermoelectric in this area that could serve as energy source in the critical times of the hydroelectric of Chivor

  13. A uranium-bearing coalificated wood remain from the Upper Carboniferous uranium ore deposit in the Baden-Baden region of the Black Forest

    International Nuclear Information System (INIS)

    Kirchheimer, F.

    1981-01-01

    From the 1973 discovered Upper Carboniferous uranium ore sandstone deposit in the Baden-Baden region (Black Forest) a uranium-bearing coalificated wood remain derived, probably the relic of a Cordaites-trunk. The chemical determinated whole uranium content of this amounts about to 40 wght.-%. Pitchblende of the collomorphic type is embedded in the vitrinite of the fossil and imitates the nearly destroyed former wood-structure. The aggregates of this mineral, surrounded by zones of contact, consist of at least two modifications of different reflectance and hardness. Radiometric analyses reveale a different disturbed radioactive equilibrium, which indicated partly loss and re-enrichment of the uranium-content in recent time. A part of the fossil is completely mineralized by pitchblende of high reflectance and associated galena. For this paragenesis the radiometric investigations proved an approached equilibrium of radioactive substances. Therefore it is to be estimated, that the pitchblende is not alterated substantially, in contrast to the embeddings in the vitrinite, rich in little reflecting and soft nasturanium. The inhomogenic mineralization of the highly coalificated fossil, also to recognise microscopically, is set in relation to the controverse genetic interpretation of the deposit. Final remarks are concerned to other uranium-enriched fossils, especially remains of bones of different origin and age. (orig.) [de

  14. Comparative organic petrology of interlayered sandstones, siltstones, mudstones and coals in the Upper Carboniferous Ruhr basin, northwest Germany, and their thermal history and methane generation

    Energy Technology Data Exchange (ETDEWEB)

    Scheidt, G.; Littke, R. (Harress Geotechnik GmbH, Floersheim (Germany, F.R.))

    1989-01-01

    In the coal-mining Ruhr-area, Upper Carboniferous rocks consist of interlayered sandstones, siltstones, mudstones and coals. They were deposited in a tropical, paralic environment where alternating fluvial sedimentation, occasional marine ingressions, and swamp growth resulted in an irregular cyclic succession. The total sedimentary package contains on an average 6 Vol.% of organic manner. About 70 Vol. % of the organic matter occurs in coal seams, the rest as dispersed organic matter in clastic rocks. The organic matter is autochthonous in the coals and allochthonous in associated sandstones and siltstones. It consists of about 70% vitrinite, 20% inertinite, and 10% liptinite. The overall maceral group composition is the same for coals and dispersed organic matter. This surprising similarity is caused by a nearly exclusive input of land-plant derived organic matter to swamps and fluvial systems and a similar degree of preservation. Highest average liptinite contents were found in unrooted mudstones, highest average inertinite contents in coarse-grained siltstones and highest average vitrinite percentages in sandstones. Maturities of the sediments studied are well within the hydrocarbon generation window, e.g. vitrinite reflectivities range from 0.6% to 1.6%. Reflectivities measured on dispersed particles in clastic rocks are similar to those measured in coal seams. Calculations of the amount of methane generated indicate that coal seams contributed more to the total hydrocarbon generation than dispersed organic matter. 51 refs., 13 figs.

  15. Devonian to Early Carboniferous magmatic alkaline activity in the Tafilalt Province, Eastearn Morocco: An Eovariscan episode in the Gondwana margin, north of the West African Craton

    Science.gov (United States)

    Pouclet, André; El Hadi, Hassan; Bardintzeff, Jacques-Marie; Benharref, Mohammed; Fekkak, Abdelilah

    2017-05-01

    To the eastern edge of the Moroccan Anti-Atlas, the Tafilalt Province is the repository of a Lower Palaeozoic platform and basin sedimentation constrained by a W-E and NW-SE fault network. During the mid-late Devonian, an extensional tectonic activity, demonstrated by sharp changes in sediment thickness and development of syn-sedimentary faults, was contemporaneous with a significant magmatic activity. A great number of doleritic dykes, sills, and laccoliths intruded sedimentary Silurian to Lower Visean strata. The intrusions were linked to sub-water volcanic activities with spilitic lava flows and pyroclastites during two main pulses in the Famennian-Tournaisian and in the Early Visean. The rocks consist of basaltic dolerites, lamprophyric dolerites and analcite-bearing camptonites, sharing a sodic alkaline magma composition. The magma derived from low partial melting degree of the metasome layer of the lithospheric subcontinental mantle, below the spinel-garnet transition zone. This Tafilalt tectono-magmatic activity was coeval with the Eovariscan phase in the Moroccan Meseta, which was responsible for the opening of Western Meseta basins and their transitional to alkaline volcanic activities in the Late Devonian to Early Carboniferous time.

  16. New evidence of effusive and explosive volcanism in the Lower Carboniferous formations of the Moroccan Central Hercynian Massif: Geochemical data and geodynamic significance

    Science.gov (United States)

    Ntarmouchant, A.; Smaili, H.; Bento dos Santos, T.; Dahire, M.; Sabri, K.; Ribeiro, M. L.; Driouch, Y.; Santos, R.; Calvo, R.

    2016-03-01

    The Azrou-Khénifra basin, located in the SE sector of the Moroccan Central Hercynian Massif of the Western Meseta of Morocco comprises volcanic and volcanoclastic rocks where two magmatic sequences can be distinguished: i) the Dhar Lahmar Sequence, composed of Upper Visean basaltic lava flows and pyroclastic deposits; and ii) the Kef Al Asri Sequence, composed of Visean - Serpukhovian intermediate to acid rocks. A continuous spatial and temporal evolution between the two volcano-sedimentary sequences was observed during the detailed geological work performed in the studied area. Petrography and geochemical studies additionally suggest a continuous compositional evolution from the more basic magmatic rocks to the intermediate/acid rocks, which implies a cogenetic magmatic differentiation controlled by crystal fractionation (with minor crustal assimilation) of a calc-alkaline trend magmatic suite. The inferred magmatic evolution is consistent with a geodynamic environment of an orogenic zone within an active continental margin setting. This partly explosive Visean - Serpukhovian volcanism, identified for the first time in the Western Meseta of Morocco, displays very similar petrographic and geochemical characteristics to its Eastern Meseta analogues, which implies that the emplacement of these magmatic rocks must have occurred in similar collisional geodynamic settings for both major geological domains, further constraining the evolution of this major crustal segment within the Carboniferous events that shaped the Hercynian Orogeny.

  17. Early Carboniferous adakite-like and I-type granites in central Qiangtang, northern Tibet: Implications for intra-oceanic subduction and back-arc basin formation within the Paleo-Tethys Ocean

    Science.gov (United States)

    Liu, Jin-Heng; Xie, Chao-Ming; Li, Cai; Wang, Ming; Wu, Hao; Li, Xing-Kui; Liu, Yi-Ming; Zhang, Tian-Yu

    2018-01-01

    Recent studies have proposed that the Late Devonian ophiolites in the central Qiangtang region of northern Tibet were formed in an oceanic back-arc basin setting, which has led to controversy over the subduction setting of the Longmucuo-Shuanghu-Lancangjiang Suture Zone (LSLSZ) during the Late Devonian to Early Carboniferous. In this paper we present new data about a suite of granite plutons that intrude into ophiolite in central Qiangtang. Our aim was to identify the type of subduction and to clarify the existence of an intra-oceanic back-arc basin in the LSLSZ during the Late Devonian to Early Carboniferous. The suite of granites consists of monzogranites, syenogranites, and granodiorites. Our laser ablation-inductively coupled plasma-mass spectrometry zircon U-Pb data yielded Early Carboniferous crystallization ages of 357.2 Ma, 357.4 Ma and 351.1 Ma. We subsequently investigated the petrogenesis and tectonic setting of these granites based on their geochemical and Hf isotopic characteristics. First, we divided the granites into high Sr/Y (HSG) and low Sr/Y granites (LSG). The HSG group contains monzogranites and granodiorites that have similar geochemical characteristics to adakites (i.e., high Sr/Y and La/Yb ratios, low MgO, Y, and Yb contents, and no pronounced negative Eu anomaly), although they have slightly lower Sr and Al2O3 contents, caused by crystal fractionation during late magmatic evolution. Therefore, we define the HSG group as adakite-like granites. The study of the HSG shows that they are adakite-like granites formed by partial melting of oceanic crust and experience fractional crystallization process during late evolution. However, some differences between the monzogranites and granodiorites indicate that there are varying degree contributions of subducted sediments during diagenesis. The LSG group contains syenogranites that have distinct negative correlations between their P2O5 and SiO2 contents, and Y and Th contents have significant positive

  18. Alluvial Mountain Meadow Source-Sink Dynamics: Land-Cover Effects on Water and Fluvial Carbon Export

    Science.gov (United States)

    Weiss, T.; Covino, T. P.; Wohl, E.; Rhoades, C.; Fegel, T.; Clow, D. W.

    2017-12-01

    Fluvial networks of historically glaciated mountain landscapes alternate between confined and unconfined valley segments. In low-gradient unconfined reaches, river-connected wet meadows commonly establish, and have been recognized as important locations of long-term water, carbon, and nutrient storage. Among connected meadow floodplains, sink-source behavior shifts as a function of flow state; storing water at high flows (snowmelt) and contributing toward higher late-season baseflows. Despite these benefits, historical and contemporary land-use practices often result in the simplification of wet meadow systems, leading to reduced river-floodplain connectivity, lower water-tables and reductions in hydrologic buffering capacity. In this study, we are exploring hydrologic-carbon relationships across a gradient of valley confinement and river-floodplain connectivity (connected, n=3; disconnected, n=4) within the Colorado Rockies. Our approach includes hydrologic analysis, fluorometric assays, water chemistry, instream metabolic measures, and land-cover assessment to examine patterns between land-form, carbon quantity and quality, and stream ecosystem productivity. Between different meadow types, preliminary results suggest differences between instream productivity, carbon qualities, and hydrologic-carbon sink-source dynamics across the season. These data and analyses will provide insight into water, carbon and nutrient flux dynamics as a function of land-cover in mountain headwaters.

  19. Mountain Weather and Climate, Third Edition

    Science.gov (United States)

    Hastenrath, Stefan

    2009-05-01

    For colleagues with diverse interests in the atmosphere, glaciers, radiation, landforms, water resources, vegetation, human implications, and more, Mountain Weather and Climate can be a valuable source of guidance and literature references. The book is organized into seven chapters: 1, Mountains and their climatological study; 2,Geographical controls of mountain meteorological elements; 3, Circulation systems related to orography; 4, Climatic characteristics of mountains; 5, Regional case studies; 6, Mountain bioclimatology; and 7, Changes in mountain climates. These chapters are supported by l78 diagrams and photographs, 47 tables, and some 2000 literature references. The volume has an appendix of units and energy conversion factors and a subject index, but it lacks an author index.

  20. Beneath it all: bedrock geology of the Catskill Mountains and implications of its weathering.

    Science.gov (United States)

    Ver Straeten, Charles A

    2013-09-01

    The Devonian-age bedrock of the Catskill Mountains has been the focus of many studies. This paper reviews the character and composition of the rocks of the Catskills, and examines weathering (rock decay) processes and their implications in the Catskills. Rocks of the Catskills and closest foothills consist of siliciclastic rocks (sandstones, mudrocks, conglomerates) with minimal, locally dispersed carbonate rocks. The former are dominated by quartz, metamorphic and sedimentary rock fragments, and clay minerals. Other minor sediment components include cements, authigenic and heavy minerals, and fossil organic matter. Physical, chemical, and biological weathering of the Catskill bedrock since uplift of the Appalachian region, combined with glaciation, have dissected a plateau of nearly horizontally layered rocks into a series of ridges, valleys, and peaks. The varied weathering processes, in conjunction with many factors (natural and anthropogenic), fragment the rocks, forming sediment and releasing various elements and compounds. These may have positive, neutral, or negative implications for the region's soils, waters, ecology, and human usage. A new generation of studies and analyses of the Catskill bedrock is needed to help answer a broad set of questions and problems across various fields of interest. © 2013 New York Academy of Sciences.

  1. Lacustrine Records of Holocene Mountain Glacier Fluctuations from Western Greenland

    Science.gov (United States)

    Schweinsberg, A.; Briner, J. P.; Bennike, O.

    2014-12-01

    Recent studies have focused on documenting fluctuations of the Greenland Ice Sheet margin throughout the Holocene but few data exist that constrain past changes of local glaciers independent of the ice sheet. Our research combines proglacial lake sediment analysis with cosmogenic 10Be dating of Holocene moraines and radiocarbon dating of ice-cap-killed vegetation with an overall objective to use this multi-proxy approach to generate a detailed record of the coupled climate-glacier system through the Holocene. Here, we present lacustrine records of mountain glacier variability from continuous pro-glacial lake sediment sequences recovered from two glaciated catchments in northeastern Nuussuaq, western Greenland. We use radiocarbon-dated sediments from Sikuiui and Pauiaivik lakes to reconstruct the timing of advance and retreat of local glaciers. Sediments were characterized with magnetic susceptibility (MS), gamma density, Itrax XRF and visible reflectance spectroscopy at 0.2 cm intervals and sediment organic matter at 0.5 cm intervals. Basal radiocarbon ages provide minimum-age constraints on deglaciation from Sikuiui and Pauiaivik lakes of ~9.6 and 8.7 ka, respectively. Organic-rich gyttja from deglaciation until ~5.0 ka in Pauiaivik Lake suggests minimal glacial extent there while slightly elevated MS values from ~9.0 - 7.0 ka in Sikuiui Lake may reflect early Holocene glacial advances. Minerogenic sediment input gradually increases starting at ~5.0 ka in Pauiaivik Lake, which we interpret as the onset of Neoglaciation in the catchment. Furthermore, a distinct episode of enhanced glacial activity from ~4.0 - 2.2 ka in Sikuiui Lake may be correlative to a period of persistent snowline lowering evidenced by radiocarbon dates of ice-killed vegetation from nearby ice cap margins. Results from these lacustrine records and our ice-killed vegetation dataset suggest a middle Holocene onset of Neoglaciation ~5.0 - 4.0 ka in this region. We are supplementing these records

  2. Evidence for submarine landslides and continental slope erosion related to fault reactivation during the last glaciation offshore eastern Canada

    Science.gov (United States)

    Saint-Ange, F.; Campbell, C.; MacKillop, K.; Mosher, D. C.; Piper, D. J.; Roger, J.

    2012-12-01

    Many studies have proposed that reactivation of dormant faults during deglaciation is a source of neotectonic activity in glaciated regions, but few have demonstrated the relationship to submarine landslides. In this study, seabed morphology and shallow geology of the outer continental margin adjacent to the Charlie Gibbs Fracture Zone off Newfoundland, Canada was investigated for evidence of this relationship. The glacial history and morphology of the margin suggest that the entire continental shelf in the area, coincident with major continental crustal lineaments, was ice-covered during the Last glacial cycle, and transverse troughs delineate the paleo-icestream drainage patterns. A recent investigation of Notre Dame Trough revealed the existence of large sediment failures on the shelf. The current study investigates complex seafloor erosion and widespread mass transport deposition (MTD) on the continental slope seaward of Notre Dame Trough, using recently-acquired high resolution seismic reflection data and piston cores. The new data reveal that a trough mouth fan (TMF) is present on the slope seaward of Notre Dame Trough. The Notre Dame TMF is characterized by a succession of stacked debris flows, but does not show a lobate shape in plan view like other classic TMFs. Instead, the Notre Dame TMF has abruptly-truncated margins suggesting post-depositional failure and erosion of the fan deposits. Seismic reflection data show that the locations of the failures along the TMF margin are coincident with a set of shallow faults; however the current dataset does not image the deeper portion of the faults. On the upper slope immediately south of the TMF, a narrow and deeply incised canyon is located along-trend with the Notre Dame Trough. The location of this canyon appears to be controlled by a fault. Downslope from this canyon, along the southern margin of the TMF, a 25 km wide, flat-floored, U-shaped valley was eroded into a succession of stacked MTD-filled channels

  3. A field and glacier modelling based approach to determine the timing and extent of glaciation in southern Africa

    Science.gov (United States)

    Mills, Stephanie C.; Rowan, Ann V.; Barrow, Timothy T.; Plummer, Mitchell A.; Smith, Michael; Grab, Stefan W.; Carr, Simon J.; Fifield, L. Keith

    2014-05-01

    Moraines identified at high-altitude sites in southern Africa and dated to the last glacial maximum (LGM) indicate that the climate in this region was cold enough to support glaciers. Small glaciers are very sensitive to changes in temperature and precipitation and the identification of LGM moraines in southern Africa has important palaeoclimatic implications concerning the magnitude of temperature change and the seasonality of precipitation during the last glacial cycle. This paper presents a refined time-frame for likely glaciations based on surface exposure dating using Cl-36 at sites in Lesotho and reports results of a 2D glacier energy balance and ice flow modelling approach (Plummer and Phillips, 2003) to evaluate the most likely climatic scenarios associated with mapped moraine limits. Samples for surface exposure dating were collected from glacially eroded bedrock at several locations and yield ages within the timescale of the LGM. Scatter in the ages may be due to insufficient erosion of the bedrock surface due to the small and relatively thin nature of the glaciers. To determine the most likely climatic conditions that may have caused the glaciers to reach their mapped extent, we use a glacier-climate model, driven by data from local weather stations and a 30m (ASTER) DEM (sub-sampled to 10m) representation of the topographic surface. The model is forced using modern climate data for primary climatic controls (temperature and precipitation) and for secondary climatic parameters (relative humidity, cloudiness, wind speed). Various sensitivity tests were run by dropping temperature by small increments and by varying the amount of precipitation and its seasonality relative to present-day values. Results suggest that glaciers could have existed in the Lesotho highlands with a temperature depression of ~5-6 ºC and that the glaciers were highly sensitive to small changes in temperature. The additional accumulation of mass through wind redistribution appears to

  4. OS X Mountain Lion bible

    CERN Document Server

    Gruman, Galen

    2012-01-01

    The complete guide to Mac OS X, fully updated for the newest release! The Mac's solid, powerful operating system and the exploding popularity of iOS devices are fueling a strong increase in market share for Apple. Previous editions of this book have sold more than 75,000 copies, and this new edition is fully updated with all the exciting features of OS X Mountain Lion, including Game Center, Messages, and Notifications. Written by industry expert Galen Gruman, it covers all the basics and then delves deep into professional and higher-end topics, making it the one book you need to succeed with

  5. Seaside, mountain and... wind turbines

    International Nuclear Information System (INIS)

    Gossement, A.

    2011-01-01

    Several courts have given a ruling considering that the law 'Montagne' (January 9., 1985) and the law 'Littoral' (January 3., 1986) are opposable to the building license of wind turbines. The law 'Littoral' imposes that any new construction in seaside areas has to be built in continuity of existing villages or hamlets. The law 'Montagne' imposes similar constraints to avoid the construction of isolated buildings in mountain areas but, contrary to the law 'Littoral', it allows some impairment for instance for the construction of certain public equipment. (A.C.)

  6. Yucca Mountain and The Environment

    International Nuclear Information System (INIS)

    NA

    2005-01-01

    The Yucca Mountain Project places a high priority on protecting the environment. To ensure compliance with all state and federal environmental laws and regulations, the Project established an Environmental Management System. Important elements of the Environmental Management System include the following: (1) monitoring air, water, and other natural resources; (2) protecting plant and animal species by minimizing land disturbance; (3) restoring vegetation and wildlife habitat in disturbed areas; (4) protecting cultural resources; (5) minimizing waste, preventing pollution, and promoting environmental awareness; and (6) managing of hazardous and non-hazardous waste. Reducing the impacts of Project activities on the environment will continue for the duration of the Project

  7. SANDIA MOUNTAIN WILDERNESS, NEW MEXICO.

    Science.gov (United States)

    Hedlund, D.C.; Kness, R.F.

    1984-01-01

    Geologic and mineral-resource investigations in the Sandia Mountains in New Mexico indicate that a small part of the area has a probable mineral-resource potential. Most of the mineral occurrences are small barite-fluorite veins that occur along faults on the eastern slope of the range. The barite veins in the Landsend area and in the Tunnel Spring area are classed as having a probable mineral-resource potential. Fluorite veins which occur at the La Luz mine contain silver-bearing galeana and the area near this mine is regarded as having a probable resource potential for silver. No energy resources were identified in this study.

  8. Protection of the Mountain Ridgelines Utilizing GIS

    Science.gov (United States)

    Lee, S.; Lee, M.

    2013-12-01

    Korean peninsula is characterized by numerous hills and mountains. The longest mountain ridgeline starting from Mt. Baekdusan to Mt. Jirisan is called Baekdudaegan which is similar to the continental divide or topographical watershed. In this study, GIS data, such as remotesensing images, national digital map, and watershed map, are used to analyze Korean mountain ridgelines structure and one Baekdudaegan data and nine Ridgelines are extracted. When extracted Baekdudaegan and other Ridgelines are overlaid on geologic maps, granite and gneiss are main components on the mountain ridgelines. The main mountain ridgelines are considered as the spiritual heritage overlapped in the land in Korea. As the environmental state is relatively better than those of other region in Korea, so many mountain ridgelines are legally protected by national legislation. The mountain ridgelines has hierarchical system; Baekdudaegan, Jeongmaek, Gimaek and Jimaek etc. according to their scale and total lengths of ridgelines. As only part of mountain ridgelines are currently protected by law or managed in environmental impact assessment (EIA) procedure, we think that most part of them should be under protection. Considering the environmental state of the ridgelines, we think that some protective measures should be set up nearby 1 km on both sides of them. If there goes a development plan or project near the main mountain ridgelines, topographical change index (TCI) and topographical scale index (TSI) etc. are to be applied in EIA. This study intends: firstly, to analyze the topological characteristics of the Korean mountain ridgelines using GIS, secondly, to analyze the geological characteristics of nearby mountain ridgelines, and lastly, to find a way to utilize the results on EIA.

  9. Coeval interaction between magmas of contrasting composition (Late Carboniferous-Early Permian Santa Eulália-Monforte massif, Ossa-Morena Zone): field relations and geochronological constraints

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, M.F.; Gama, C.; Rodríguez, C.

    2017-07-01

    The Santa Eulália-Monforte massif is a post-kinematic Late Carboniferous-Early Permian calc-alkaline composite massif (LC-EP) located in the Ossa-Morena Zone (OMZ, Portugal). This paper examines the field relationships between pinkish granites and mafic-intermediate rocks from the external ring of this massif and presents new U-Pb zircon age determinations. The estimated 206Pb/238U ages, 297±4Ma for the pinkish granite and 303±3Ma for a gabbro-diorite point to a short time interval between the crystallization of both magmas. At outcrop scale, contacts of the mafic-intermediate rocks with the host pinkish granite are sharp and corroborate this age relationship, but do not justify why the host-enclave contacts often has curved and irregular shapes, indicating liquid-liquid interaction. A full analysis of the distribution of U-Pb zircon ages and respective Th/U ratios suggests that the compositionally distinct magmas were roughly contemporaneous. The obtained ages also fit the LC-EP Iberian calc-alkaline suite that was formed contemporaneously to the development of the Iberian-Armorican Arc and when the Paleotethyan oceanic Plate subducted under the Eurasian active margin. Taking this geodynamic setting as a reference, the LC-EP Iberian calc-alkaline magmatism can be interpreted as most probably related to the Cimmerian cycle instead of the traditionally accepted model that ascribe a closer connection of this magmatism with the Variscan cycle. The Santa Eulália-Monforte massif is a post-kinematic Late Carboniferous-Early Permian calc-alkaline composite massif (LC-EP) located in the Ossa-Morena Zone (OMZ, Portugal). This paper examines the field relationships between pinkish granites and mafic-intermediate rocks from the external ring of this massif and presents new U-Pb zircon age determinations. The estimated 206Pb/238U ages, 297±4Ma for the pinkish granite and 303±3Ma for a gabbro-diorite point to a short time interval between the crystallization of both

  10. Coeval interaction between magmas of contrasting composition (Late Carboniferous-Early Permian Santa Eulália-Monforte massif, Ossa-Morena Zone): field relations and geochronological constraints

    International Nuclear Information System (INIS)

    Pereira, M.F.; Gama, C.; Rodríguez, C.

    2017-01-01

    The Santa Eulália-Monforte massif is a post-kinematic Late Carboniferous-Early Permian calc-alkaline composite massif (LC-EP) located in the Ossa-Morena Zone (OMZ, Portugal). This paper examines the field relationships between pinkish granites and mafic-intermediate rocks from the external ring of this massif and presents new U-Pb zircon age determinations. The estimated 206Pb/238U ages, 297±4Ma for the pinkish granite and 303±3Ma for a gabbro-diorite point to a short time interval between the crystallization of both magmas. At outcrop scale, contacts of the mafic-intermediate rocks with the host pinkish granite are sharp and corroborate this age relationship, but do not justify why the host-enclave contacts often has curved and irregular shapes, indicating liquid-liquid interaction. A full analysis of the distribution of U-Pb zircon ages and respective Th/U ratios suggests that the compositionally distinct magmas were roughly contemporaneous. The obtained ages also fit the LC-EP Iberian calc-alkaline suite that was formed contemporaneously to the development of the Iberian-Armorican Arc and when the Paleotethyan oceanic Plate subducted under the Eurasian active margin. Taking this geodynamic setting as a reference, the LC-EP Iberian calc-alkaline magmatism can be interpreted as most probably related to the Cimmerian cycle instead of the traditionally accepted model that ascribe a closer connection of this magmatism with the Variscan cycle. The Santa Eulália-Monforte massif is a post-kinematic Late Carboniferous-Early Permian calc-alkaline composite massif (LC-EP) located in the Ossa-Morena Zone (OMZ, Portugal). This paper examines the field relationships between pinkish granites and mafic-intermediate rocks from the external ring of this massif and presents new U-Pb zircon age determinations. The estimated 206Pb/238U ages, 297±4Ma for the pinkish granite and 303±3Ma for a gabbro-diorite point to a short time interval between the crystallization of both

  11. Mountaineers

    OpenAIRE

    Thomson, John, 1837-1921, photographer

    2003-01-01

    89 x 110 mm. Woodburytype. A half-length portrait of a seated man from the village of Prodromos. The portrait appears in Thomson's 'Through Cyprus with the camera, in the autumn of 1878' (vol.2, London: Sampson Low, Marston, Searle, and Rivington, 1879). It is annotated: 'The villagers are a robust race, as may be gathered from the two following photographs, the first of which represents one of the chief people of the place, a man who deserves to be rendered famous for the kind manner in w...

  12. Mountaineers

    OpenAIRE

    Thomson, John, 1837-1921, photographer

    2003-01-01

    84 x 107 mm. Woodburytype. A posed portrait of a man from Prodromos. The portrait appears in Thomson's 'Through Cyprus with the camera, in the autumn of 1878' (vol.2, London: Sampson Low, Marston, Searle, and Rivington, 1879). It is annotated: 'Another Highlander figures in the second plate - a tall, bony man of a most obligingly good-natured disposition. He, however, looked a bold, determined character, whose massive hands and muscular frame would stand him in good stead in carrying out ...

  13. Rocky Mountain Research Station: 2011 Annual Accomplishments

    Science.gov (United States)

    Rick Fletcher

    2011-01-01

    The Rocky Mountain Research Station is one of seven regional units that make up the USDA Forest Service Research and Development organization ­ the most extensive natural resources research organization in the world. We maintain 12 field laboratories throughout a 12-state territory encompassing the Great Basin, Southwest, Rocky Mountains, and parts of the Great Plains...

  14. Rocky Mountain Research Station: 2010 Research Accomplishments

    Science.gov (United States)

    Rick Fletcher

    2010-01-01

    The Rocky Mountain Research Station is one of seven regional units that make up the USDA Forest Service Research and Development organization ­ the most extensive natural resources research organization in the world. We maintain 12 field laboratories throughout a 12-state territory encompassing the Great Basin, Southwest, Rocky Mountains, and parts of the Great Plains...

  15. Impact of Hypoxia on Man on Mountaineering

    Directory of Open Access Journals (Sweden)

    A. N. Kislitsyn

    2006-01-01

    Full Text Available External respiratory function was studied in those engaged in mountaineering. A negative correlation was found between the intensity of exercise and the changes in vital capacity under mountainous conditions. Changes occurring in the levels of glucose and cholesterol were considered in tourists.

  16. Rocky Mountain spotted fever in children.

    Science.gov (United States)

    Woods, Charles R

    2013-04-01

    Rocky Mountain spotted fever is typically undifferentiated from many other infections in the first few days of illness. Treatment should not be delayed pending confirmation of infection when Rocky Mountain spotted fever is suspected. Doxycycline is the drug of choice even for infants and children less than 8 years old. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Rocky Mountain Spotted Fever: Statistics and Epidemiology

    Science.gov (United States)

    ... Search Form Controls Cancel Submit Search the CDC Rocky Mountain Spotted Fever (RMSF) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Rocky Mountain Spotted Fever (RMSF) Transmission Signs and Symptoms Diagnosis and Testing ...

  18. 78 FR 29366 - Green Mountain Power Corporation

    Science.gov (United States)

    2013-05-20

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. TS04-277-002] Green Mountain Power Corporation Notice of Filing Take notice that on May 2, 2013, Green Mountain Power Corporation filed additional information in support of its request for continued waiver of Standards of Conduct. Any...

  19. The Carboniferous-Permian boundary in the central western Argentinean basins: paleontological evidences El límite Carbonífero-Pérmico en las cuencas del centro oeste de Argentina: evidencias paleontológicas

    Directory of Open Access Journals (Sweden)

    Gabriela A Cisterna

    2011-07-01

    Full Text Available The central western Argentinean basins of Río Blanco, Calingasta-Uspallata and western Paganzo, enclose the most complete marine successions used for examining the Carboniferous-Permian boundary in Gondwana. A detailed review of the key stratigraphical sections has allowed the identification of the latest Carboniferous assemblages; NBG, Interval megafloristic Zone and DM (Raistrickia densa-Convolutispora muriornata Palynological Zone in the lower part, and the earliest Permian T-S (Tivertonia jachalensis-Streptorhynchus inaequiornatus invertebrate Zone and FS (Pakhapitesfusus-Vittatina subsaccata Palynological Zone in the upper part. This diagnostic mega/microflora and marine invertebrate paleontological evidence provides a biostratigraphical framework for the definition of the Carboniferous-Permian boundary inside the basins of central western Argentina.Las cuencas del centro oeste de Argentina, Río Blanco, Calingasta-Uspallata y el sector oeste de la cuenca Paganzo, contienen las secuencias marinas más completas para el estudio del límite Carbonífero-Pérmico en Gondwana. Un estudio detallado de secciones estratigráficas claves ha permitido la identificación de las asociaciones megaflo-rísticas NBG y de Intervalo, y de la palinozona DM (Raistrickia densa-Convolutispora muriornata, del Carbonífero Tardío, en la parte inferior de dichas secciones; en tanto, en la parte media superior de las secciones estudiadas, se han identificado la biozona de invertebrados T-S (Tivertonia jachalensis-Streptorhynchus inaequiornatus y la palinozona FS (Pakhapites fusus-Vittatina subsaccata, ambas asignadas al Pérmico Temprano. El registro de estas asociaciones diagnósticas de mega/microflora e invertebrados marinos provee un esquema bioestratigráfico integrado que permite ubicar el límite Carbonífero-Pérmico en las cuencas del centro oeste de Argentina.

  20. A sightability model for mountain goats

    Science.gov (United States)

    Rice, C.G.; Jenkins, K.J.; Chang, W.-Y.

    2009-01-01

    Unbiased estimates of mountain goat (Oreamnos americanus) populations are key to meeting diverse harvest management and conservation objectives. We developed logistic regression models of factors influencing sightability of mountain goat groups during helicopter surveys throughout the Cascades and Olympic Ranges in western Washington during summers, 20042007. We conducted 205 trials of the ability of aerial survey crews to detect groups of mountain goats whose presence was known based on simultaneous direct observation from the ground (n 84), Global Positioning System (GPS) telemetry (n 115), or both (n 6). Aerial survey crews detected 77 and 79 of all groups known to be present based on ground observers and GPS collars, respectively. The best models indicated that sightability of mountain goat groups was a function of the number of mountain goats in a group, presence of terrain obstruction, and extent of overstory vegetation. Aerial counts of mountain goats within groups did not differ greatly from known group sizes, indicating that under-counting bias within detected groups of mountain goats was small. We applied HorvitzThompson-like sightability adjustments to 1,139 groups of mountain goats observed in the Cascade and Olympic ranges, Washington, USA, from 2004 to 2007. Estimated mean sightability of individual animals was 85 but ranged 0.750.91 in areas with low and high sightability, respectively. Simulations of mountain goat surveys indicated that precision of population estimates adjusted for sightability biases increased with population size and number of replicate surveys, providing general guidance for the design of future surveys. Because survey conditions, group sizes, and habitat occupied by goats vary among surveys, we recommend using sightability correction methods to decrease bias in population estimates from aerial surveys of mountain goats.

  1. AHP 21: Review: Moving Mountains

    Directory of Open Access Journals (Sweden)

    William B. Noseworthy

    2012-12-01

    Full Text Available Moving Mountains stands out among recent discussions of the Southeast Asian Highlands, drawing from twelve contributors with extensive field experience living and working in locales closed to nonCommunist academics between 1945 and 1990 (3. The authors' methodologies focus on the anthropological approach of participant observation combined with oral history. Previously, substantial research had been confined to the experience of "hill tribes" in Northern Thailand (11, unless one gained access to the massive collections of French language research under the École Française d'Extrême Orient (EFEO or the Société Asiatique (SA, both in Paris. As such, this volume's contributors are able to ring out the voices of Southeast Asian Massif populations in a way that demonstrates a mindful assembly of research, while carefully narrating a more complex view of the region than that presented by Scott's (2009:22 "zones of refuge." ...

  2. Natural analogs for Yucca Mountain

    International Nuclear Information System (INIS)

    Murphy, W.M.

    1995-01-01

    High-level radioactive waste in the US, spent fuels from commercial reactors and nuclear materials generated by defense activities, will remain potentially hazardous for thousands of years. Demonstrable long-term stability of certain geologic and geochemical systems motivates and sustains the concept that high-level waste can be safely isolated in geologic repositories for requisite periods of time. Each geologic repository is unique in its properties and performance with reguard to isolation of nuclear wastes. Studies of processes analogous to waste-form alteration and radioelement transport in environments analogous to Yucca Mountain are being conducted at two sites, described in this article to illustrate uses of natural analog data: the Nopal I uranium deposit in the Sierra Pena Blanca, Mexico, and the Akrotiri archaeological site on the island of Santorini, Greece

  3. Occupational Health in Mountainous Kyrgyzstan.

    Science.gov (United States)

    Dzhusupov, Kenesh O; Colosio, Claudio; Tabibi, Ramin; Sulaimanova, Cholpon T

    2015-01-01

    In the period of transition from a centralized economy to the market economy, occupational health services in Kyrgyzstan have survived through dramatic, detrimental changes. It is common for occupational health regulations to be ignored and for basic occupational health services across many industrial enterprises and farms to be neglected. The aim of this study was to demonstrate the present situation and challenges facing occupational health services in Kyrgyzstan. The transition from centralized to the market economy in Kyrgyzstan has led to increased layoffs of workers and unemployment. These threats are followed by increased workload, and the health and safety of workers becomes of little concern. Private employers ignore occupational health and safety; consequently, there is under-reporting of occupational diseases and accidents. The majority of enterprises, especially those of small or medium size, are unsanitary, and the health status of workers remains largely unknown. The low official rates of occupational diseases are the result of data being deliberately hidden; lack of coverage of working personnel by medical checkups; incompetent management; and the poor quality of staff, facilities, and equipment. Because Kyrgyzstan is a mountainous country, the main environmental and occupational factor of enterprises is hypoxia. Occupational health specialists have greatly contributed to the development of occupational medicine in the mountains through science and practice. The enforcement of existing strong occupational health legislation and increased financing of occupational health services are needed. The maintenance of credible health monitoring and effective health services for workers, re-establishment of medical services and sanitary-hygienic laboratories in industrial enterprises, and support for scientific investigations on occupational risk assessment will increase the role of occupational health services in improving the health of the working population

  4. Mountain laurel toxicosis in a dog.

    Science.gov (United States)

    Manhart, Ingrid O; DeClementi, Camille; Guenther, Christine L

    2013-01-01

    To describe a case of mountain laurel (Kalmia latifolia) toxicosis in a dog, including case management and successful outcome. A dog presented for vomiting, hematochezia, bradycardia, weakness, and ataxia, which did not improve with supportive treatment. Mountain laurel ingestion was identified as cause of clinical signs after gastrotomy was performed to remove stomach contents. Supportive treatment was continued and the dog made a full recovery. This report details a case of mountain laurel toxicosis in a dog, including management strategies and outcome, which has not been previously published in the veterinary literature. © Veterinary Emergency and Critical Care Society 2013.

  5. Transport of neptunium through Yucca Mountain tuffs

    International Nuclear Information System (INIS)

    Triay, I.R.; Robinson, B.A.; Mitchell, A.J.; Overly, C.M.; Lopez, R.M.

    1993-01-01

    Neptunium has a high solubility in groundwaters from Yucca Mountain [1]. Uranium in nuclear reactors produces 237 Np which has a half-life of 2.1 4 x 10 6 years. Consequently, the transport of 237 Np through tuffs is of major importance in assessing the performance of a high-level nuclear waste repository at Yucca Mountain. The objective of this work is to determine the amount of Np retardation that is provided by the minerals in Yucca Mountain tuffs as a function of groundwater chemistry

  6. The polycyclic Lausche Volcano (Lausitz Volcanic Field) and its message concerning landscape evolution in the Lausitz Mountains (northern Bohemian Massif, Central Europe)

    Science.gov (United States)

    Wenger, Erik; Büchner, Jörg; Tietz, Olaf; Mrlina, Jan

    2017-09-01

    The Tertiary Lausitz Volcanic Field covers a broad area encompassing parts of Eastern Saxony (Germany), Lower Silesia (Poland) and North Bohemia (Czech Republic). Volcanism was predominantly controlled by the volcano-tectonic evolution of the Ohře Rift and culminated in the Lower Oligocene. This paper deals with the highest volcano of this area, the Lausche Hill (792.6 m a.s.l.) situated in the Lausitz Mountains. We offer a reconstruction of the volcanic edifice and its eruptive history. Its complex genesis is reflected by six different eruption styles and an associated petrographic variety. Furthermore, the Lausche Volcano provides valuable information concerning the morphological evolution of its broader environs. The remnant of an alluvial fan marking a Middle Paleocene-Lower Eocene (62-50 Ma) palaeo-surface is preserved at the base of the volcano. The deposition of this fan can be attributed to a period of erosion of its nearby source area, the Lausitz Block that has undergone intermittent uplift at the Lausitz Overthrust since the Upper Cretaceous. The Lausche Hill is one of at least six volcanoes in the Lausitz Mountains which show an eminent low level of erosion despite their Oligocene age and position on elevated terrain. These volcanoes are exposed in their superficial level which clearly contradicts their former interpretation as subvolcanoes. Among further indications, this implies that the final morphotectonic uplift of the Lausitz Mountains started in the upper Lower Pleistocene ( 1.3 Ma) due to revived subsidence of the nearby Zittau Basin. It is likely that this neotectonic activity culminated between the Elsterian and Saalian Glaciation ( 320 ka). The formation of the low mountain range was substantially controlled by the intersection of the Lausitz Overthrust and the Ohře Rift.

  7. Shahejie-Shahejie/Guantao/Wumishan and Carboniferous/Permian Coal-Paleozoic Total Petroleum Systems in the Bohaiwan Basin, China (based on geologic studies for the 2000 World Energy Assessment Project of the U.S. Geological Survey)

    Science.gov (United States)

    Ryder, Robert T.; Qiang, Jin; McCabe, Peter J.; Nuccio, Vito F.; Persits, Felix

    2012-01-01

    This report discusses the geologic framework and petroleum geology used to assess undiscovered petroleum resources in the Bohaiwan basin province for the 2000 World Energy Assessment Project of the U.S. Geological Survey. The Bohaiwan basin in northeastern China is the largest petroleum-producing region in China. Two total petroleum systems have been identified in the basin. The first, the Shahejie&ndashShahejie/Guantao/Wumishan Total Petroleum System, involves oil and gas generated from mature pods of lacustrine source rock that are associated with six major rift-controlled subbasins. Two assessment units are defined in this total petroleum system: (1) a Tertiary lacustrine assessment unit consisting of sandstone reservoirs interbedded with lacustrine shale source rocks, and (2) a pre-Tertiary buried hills assessment unit consisting of carbonate reservoirs that are overlain unconformably by Tertiary lacustrine shale source rocks. The second total petroleum system identified in the Bohaiwan basin is the Carboniferous/Permian Coal–Paleozoic Total Petroleum System, a hypothetical total petroleum system involving natural gas generated from multiple pods of thermally mature coal beds. Low-permeability Permian sandstones and possibly Carboniferous coal beds are the reservoir rocks. Most of the natural gas is inferred to be trapped in continuous accumulations near the center of the subbasins. This total petroleum system is largely unexplored and has good potential for undiscovered gas accumulations. One assessment unit, coal-sourced gas, is defined in this total petroleum system.

  8. Discontinuities and sequences in the Tarat formation (Upper Visean) and the Arlit Unit (Namurian-Westphalian) at Arlit (Niger). Sedimentary climatic and tectonic evolution of the area during Carboniferous

    International Nuclear Information System (INIS)

    Sempere, T.; Beaudoin, B.

    1984-01-01

    The Tarat Formation is composed at Arlit of three sequences consisting of sandstones and black mudstones rich in organic matter of continental origin. The three of them are interpreted as estuarine sediments deposited in different tectonic frameworks. The Arlit Unit consists of motley argillaceous sandstones deposited in a very flat lacustrine or alluvial environment and under an arid climate. These formations are separated by a fundamental discontinuity linked to the structuration of the Tim Mersoi Trough. At regional scale, the sediments lying below this discontinuity are grouped in tectono-sedimentary supersequences, which are interpreted as biorhexistasic rhythms; their deposition was horizontally directed by complex evolving synsedimentary tectonics controlled by the N-S In Azawa Lineament, and was influenced by the permanent proximity of a northern sea. The sediments lying above the fundamental discontinuity belong to the ''Continental Intercalaire'' Supergroup; their deposition was influenced by the Tim Mersoi Trough. The whole Carboniferous sedimentation took place in a climatic context which evolved from cold (Lower Visean) to warm and arid (Upper Carboniferous) through temperate climates [fr

  9. Annual Copper Mountain Conferences on Multigrid and Iterative Methods, Copper Mountain, Colorado

    International Nuclear Information System (INIS)

    McCormick, Stephen F.

    2016-01-01

    This project supported the Copper Mountain Conference on Multigrid and Iterative Methods, held from 2007 to 2015, at Copper Mountain, Colorado. The subject of the Copper Mountain Conference Series alternated between Multigrid Methods in odd-numbered years and Iterative Methods in even-numbered years. Begun in 1983, the Series represents an important forum for the exchange of ideas in these two closely related fields. This report describes the Copper Mountain Conference on Multigrid and Iterative Methods, 2007-2015. Information on the conference series is available at http://grandmaster.colorado.edu/~copper/

  10. Recent population trends of mountain goats in the Olympic Mountains, Washington

    Science.gov (United States)

    Jenkins, Kurt J.; Happe, Patricia J.; Beirne, Katherine F.; Hoffman, Roger A.; Griffin, Paul C.; Baccus, William T.; Fieberg, John

    2012-01-01

    Mountain goats (Oreamnos americanus) were introduced in Washington's Olympic Mountains during the 1920s. The population subsequently increased in numbers and expanded in range, leading to concerns by the 1970s over the potential effects of non-native mountain goats on high-elevation plant communities in Olympic National Park. The National Park Service (NPS) transplanted mountain goats from the Olympic Mountains to other ranges between 1981 and 1989 as a means to manage overabundant populations, and began monitoring population trends of mountain goats in 1983. We estimated population abundance of mountain goats during 18–25 July 2011, the sixth survey of the time series, to assess current population status and responses of the population to past management. We surveyed 39 sample units, comprising 39% of the 59,615-ha survey area. We estimated a population of 344 ± 72 (90% confidence interval [CI]) mountain goats in the survey area. Retrospective analysis of the 2004 survey, accounting for differences in survey area boundaries and methods of estimating aerial detection biases, indicated that the population increased at an average annual rate of 4.9% since the last survey. That is the first population growth observed since the cessation of population control measures in 1990. We postulate that differences in population trends observed in western, eastern, and southern sections of the survey zone reflected, in part, a variable influence of climate change across the precipitation gradient in the Olympic Mountains.

  11. Annual Copper Mountain Conferences on Multigrid and Iterative Methods, Copper Mountain, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, Stephen F. [Front Range Scientific, Inc., Lake City, CO (United States)

    2016-03-25

    This project supported the Copper Mountain Conference on Multigrid and Iterative Methods, held from 2007 to 2015, at Copper Mountain, Colorado. The subject of the Copper Mountain Conference Series alternated between Multigrid Methods in odd-numbered years and Iterative Methods in even-numbered years. Begun in 1983, the Series represents an important forum for the exchange of ideas in these two closely related fields. This report describes the Copper Mountain Conference on Multigrid and Iterative Methods, 2007-2015. Information on the conference series is available at http://grandmaster.colorado.edu/~copper/.

  12. Radioecological situation in the Khibiny mountains

    International Nuclear Information System (INIS)

    Sedova, N.B.

    2008-01-01

    Radioecological situation in the Khibiny Mountains is considered. Two former areas of engineering nuclear explosions are monitored. The accumulation and migration of radionuclides in soil, vegetation and snow are examined.

  13. VT Green Mountain Power Pole Data

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Green Mountain Power (GMP) pole and OVERHEAD linear distribution/sub-transmission model data. THE LINEAR DISTRIBUTION LAYER ONLY INCLUDES OVERHEAD...

  14. VT Green Mountain National Forest - Roads

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) GMNFTRAILS contains minor Forest Service roads and all trails within the proclamation boundary of the Green Mountain National Forest and many of...

  15. Mountain Wave Analysis Using Fourier Methods

    National Research Council Canada - National Science Library

    Roadcap, John R

    2007-01-01

    ...) their requirements for only a coarse horizontal background state. Common traits of Fourier mountain wave models include use of the Boussinesq approximation and neglect of moisture and Coriolis terms...

  16. MOUNTAIN TOURISM-PLEASURE AND NECESSITY

    Directory of Open Access Journals (Sweden)

    Gabriela Corina SLUSARIUC

    2015-07-01

    Full Text Available Tourism has a more and more important role in the economic development of many countries. Mountain tourism is an anti-stress solutions and a type of disconnection from the citadel life style through replacing some activities of media consuming type, games and virtual socializing with therapy through movement, the physical activity being an essential dimension in assuring the high life quality. Mountaineering is searched for: practicing winter sports, its invigorating and comforting, relaxing role, medical spa treatments practicing hiking, alpinism. Mountain tourism generates increased economic benefits for the surrounding areas, improves the life quality of the local communities and can assure the prosperity of some disadvantaged areas, being able to be a remedy for unindustrialised regions. Mountain tourism contributes to the economic development of the region and also to satisfying spiritual and psychological needs of the people, representing a necessity for a touristic area and a pleasure for tourist consumers.

  17. Nuclear Waste Disposal: Alternatives to Yucca Mountain

    National Research Council Canada - National Science Library

    Holt, Mark

    2009-01-01

    Congress designated Yucca Mountain, NV, as the nation's sole candidate site for a permanent high-level nuclear waste repository in 1987, following years of controversy over the site-selection process...

  18. Alternative transportation study : Wichita Mountains Wildlife Refuge

    Science.gov (United States)

    2010-08-01

    This report provides an assessment of historic and current visitation, infrastructure, and transportation conditions at the Wichita Mountains Wildlife Refuge and surrounding areas in southwest Oklahoma. The study defines transportation-related goals ...

  19. VT Green Mountain National Forest - Trails

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) GMNFTRAILS contains minor Forest Service roads and all trails within the proclamation boundary of the Green Mountain National Forest and many of...

  20. Rethinking risk and disasters in mountain areas

    OpenAIRE

    Hewitt, Kenneth; Mehta, Manjari

    2012-01-01

    This chapter presents a view of risk and disaster in the mountains that finds them fully a part of public safety issues in modern states and developments, rather than separated from them. This contrasts with prevailing approaches to disaster focused on natural hazards, “unscheduled” or extreme events, and emergency preparedness; approaches strongly reinforced by mountain stereotypes. Rather, we find the legacies of social and economic histories, especially relations to down-country or metropo...

  1. CURRENT MICROBIOLOGICAL ASPECTS IN HIGH MOUNTAIN

    OpenAIRE

    KURT HANSELMANN; MUNTI YUHANA

    2006-01-01

    Remote and normally unpolluted high mountain lakes provide habitats with no or very limited anthropogenic influences and, therefore, their hydrodynamics are mostly regulated by the natural c onditions. Researches in high mountain lakes deal with measuring and modeling the response of the habitats to environmental changes especially correlated to acid deposition, pollutants influx and climatic variability. The microbial world has also become a focus in many studies of these extreme ecosystem...

  2. AHP 35: An Abandoned Mountain Deity

    Directory of Open Access Journals (Sweden)

    Limusishiden (Li Dechun 李得春

    2015-02-01

    Full Text Available Lasizi are cairns where mountain deities dwell, and the same word also refers to the deities that dwell in these cairns. There are many lasizi in Tu areas in Huzhu Tu Autonomous County, Haidong Municipality, Qinghai Province. The most famous are: Chileb, located in the north part of both Danma Town and Donggou Township Durizang, located in the northern part of Wushi Town Lawa, located atop a mountain on the border between Danma Town and Wushi Town. The mountain is referred to as Lawa Lasizi. Lawa Village is located at the foot of Lawa Lasizi's west side, which is within Danma Town territory. Tughuan Village is located at the foot of Lawa Lasizi's east side, which belongs is within Wushi Town jurisdiction. Sughua, located atop a mountain on the border between Danma Town and Dongshan Township. The mountain is locally known as Sughua Lasizi. Qighaan Dawa Village is located at the foot of Sughua Lasizi's west side, which is part of Dongshan Township. Sughua Village is located at the foot of Sughua Lasizi's east side, which is part of belongs Danma Town. Walighuan, located atop a mountain in Hongyazigou Township and Sunduu, located on the border between Songduo and Bazha (two autonomous Tibetan townships in Huzhu County and Ledu Region. ...

  3. New age constraints for the Saalian glaciation in northern central Europe: Implications for the extent of ice sheets and related proglacial lake systems

    Science.gov (United States)

    Lang, Jörg; Lauer, Tobias; Winsemann, Jutta

    2018-01-01

    A comprehensive palaeogeographic reconstruction of ice sheets and related proglacial lake systems for the older Saalian glaciation in northern central Europe is presented, which is based on the integration of palaeo-ice flow data, till provenance, facies analysis, geomorphology and new luminescence ages of ice-marginal deposits. Three major ice advances with different ice-advance directions and source areas are indicated by palaeo-ice flow directions and till provenance. The first ice advance was characterised by a southwards directed ice flow and a dominance of clasts derived from southern Sweden. The second ice advance was initially characterised by an ice flow towards the southwest. Clasts are mainly derived from southern and central Sweden. The latest stage in the study area (third ice advance) was characterised by ice streaming (Hondsrug ice stream) in the west and a re-advance in the east. Clasts of this stage are mainly derived from eastern Fennoscandia. Numerical ages for the first ice advance are sparse, but may indicate a correlation with MIS 8 or early MIS 6. New pIRIR290 luminescence ages of ice-marginal deposits attributed to the second ice advance range from 175 ± 10 to 156 ± 24 ka and correlate with MIS 6. The ice sheets repeatedly blocked the main river-drainage pathways and led to the formation of extensive ice-dammed lakes. The formation of proglacial lakes was mainly controlled by ice-damming of river valleys and major bedrock spillways; therefore the lake levels and extends were very similar throughout the repeated ice advances. During deglaciation the lakes commonly increased in size and eventually drained successively towards the west and northwest into the Lower Rhine Embayment and the North Sea. Catastrophic lake-drainage events occurred when large overspill channels were suddenly opened. Ice-streaming at the end of the older Saalian glaciation was probably triggered by major lake-drainage events.

  4. Scientific progress at Yucca Mountain

    International Nuclear Information System (INIS)

    Gertz, C.P.

    1990-01-01

    The US Department of Energy (DOE) is moving forward with studies to determine whether Yucca Mountain, Nevada, would be a suitable site for the nation's first high-level radioactive waste repository; however, the DOE's Congressionally mandated task of characterizing the site has been severely delayed by a lack of cooperation from the state of Nevada. The state has refused to issue the appropriate permits that must be obtained before surface disturbing studies can proceed; therefore, an extensive surface-based drilling and trenching program and construction of underground exploration facilities are on hold until pending litigation between the DOE and Nevada has been resolved. Despite this major impasse, significant scientific progress has been made, and the DOE is aggressively pursuing investigations that can be conducted without the state-issued permits. Additionally, the DOE is developing a high-quality technical and management structure as well as equipment, plans, and quality assurance procedures, so that the scientific investigation program can proceed without delay once the appropriate permits are obtained

  5. ADVANCES IN YUCCA MOUNTAIN DESIGN

    International Nuclear Information System (INIS)

    Harrington, P.G.; Gardiner, J.T.; Russell, P.R.Z.; Lachman, K.D.; McDaniel, P.W.; Boutin, R.J.; Brown, N.R.; Trautner, L.J.

    2003-01-01

    Since site designation of the Yucca Mountain Project by the President, the U.S. Department of Energy (DOE) has begun the transition from the site characterization phase of the project to preparation of the license application. As part of this transition, an increased focus has been applied to the repository design. Several evolution studies were performed to evaluate the repository design and to determine if improvements in the design were possible considering advances in the technology for handling and packaging nuclear materials. The studies' main focus was to reduce and/or eliminate uncertainties in both the pre-closure and post-closure performance of the repository and to optimize operations. The scope and recommendations from these studies are the subjects of this paper and include the following topics: (1) a more phased approach for the surface facility that utilize handling and packaging of the commercial spent nuclear fuel in a dry environment rather than in pools as was presented in the site recommendation; (2) slight adjustment of the repository footprint and a phased approach for construction and emplacement of the repository subsurface; and (3) simplification of the construction, fabrication and installation of the waste package and drip shield

  6. Population genetic structure and demographic history of the freshwater crab Potamon elbursi (Brachyura: Potamidae from the Alborz Mountains in northern Iran

    Directory of Open Access Journals (Sweden)

    Alireza Keikhosravi

    2015-04-01

    Full Text Available Hydrographically separated populations of the freshwater crab Potamon elbursi Pretzmann, 1976 were genetically investigated to assess their local diversity and to reconstruct the possible role of Quaternary glaciations in shaping current diversity in the Alborz Mountains, northern Iran. A total of 61 specimens from six rivers were collected from the two different drainage systems of the Alborz Mountains, Namak Lake and the South Caspian watershed. A comparative analysis of a partial sequence of the mitochondrial cytochrome oxidase subunit I gene revealed relatively high overall haplotype diversity and low nucleotide diversity. In four populations, there is no association between the haplotype network and the geographical separation between drainages, whereas the remaining two populations consist of private haplotypes. Gene flow among rivers was estimated using pairwise differences of Φst; in almost all cases gene flow was significantly restricted, regardless of association to a particular river system. Surprisingly, the only exception was the pairwise comparison of two distant rivers belonging to different drainages; this lack of differentiation may be attributed to incomplete lineage sorting or secondary introduction events. The mismatch distribution analysis, together with the shape of the haplotype network and the nucleotide and haplotype diversity indices, indicates that the studied metapopulation show the signature of recent population bottlenecks followed by demographic or spatial expansion and dating back to Pleistocene climatic fluctuations. 

  7. Phylogeographic Structure of a Tethyan Relict Capparis spinosa (Capparaceae) Traces Pleistocene Geologic and Climatic Changes in the Western Himalayas, Tianshan Mountains, and Adjacent Desert Regions.

    Science.gov (United States)

    Wang, Qian; Zhang, Ming-Li; Yin, Lin-Ke

    2016-01-01

    Complex geological movements more or less affected or changed floristic structures, while the alternation of glacials and interglacials is presumed to have further shaped the present discontinuous genetic pattern of temperate plants. Here we consider Capparis spinosa, a xeromorphic Tethyan relict, to discuss its divergence pattern and explore how it responded in a stepwise fashion to Pleistocene geologic and climatic changes. 267 individuals from 31 populations were sampled and 24 haplotypes were identified, based on three cpDNA fragments (trnL-trnF, rps12-rpl20, and ndhF). SAMOVA clustered the 31 populations into 5 major clades. AMOVA suggests that gene flow between them might be restricted by vicariance. Molecular clock dating indicates that intraspecific divergence began in early Pleistocene, consistent with a time of intense uplift of the Himalaya and Tianshan Mountains, and intensified in mid-Pleistocene. Species distribution modeling suggests range reduction in the high mountains during the Last Glacial Maximum (LGM) as a result of cold climates when glacier advanced, while gorges at midelevations in Tianshan appear to have served as refugia. Populations of low-altitude desert regions, on the other hand, probably experienced only marginal impacts from glaciation, according to the high levels of genetic diversity.

  8. Phylogeographic Structure of a Tethyan Relict Capparis spinosa (Capparaceae Traces Pleistocene Geologic and Climatic Changes in the Western Himalayas, Tianshan Mountains, and Adjacent Desert Regions

    Directory of Open Access Journals (Sweden)

    Qian Wang

    2016-01-01

    Full Text Available Complex geological movements more or less affected or changed floristic structures, while the alternation of glacials and interglacials is presumed to have further shaped the present discontinuous genetic pattern of temperate plants. Here we consider Capparis spinosa, a xeromorphic Tethyan relict, to discuss its divergence pattern and explore how it responded in a stepwise fashion to Pleistocene geologic and climatic changes. 267 individuals from 31 populations were sampled and 24 haplotypes were identified, based on three cpDNA fragments (trnL-trnF, rps12-rpl20, and ndhF. SAMOVA clustered the 31 populations into 5 major clades. AMOVA suggests that gene flow between them might be restricted by vicariance. Molecular clock dating indicates that intraspecific divergence began in early Pleistocene, consistent with a time of intense uplift of the Himalaya and Tianshan Mountains, and intensified in mid-Pleistocene. Species distribution modeling suggests range reduction in the high mountains during the Last Glacial Maximum (LGM as a result of cold climates when glacier advanced, while gorges at midelevations in Tianshan appear to have served as refugia. Populations of low-altitude desert regions, on the other hand, probably experienced only marginal impacts from glaciation, according to the high levels of genetic diversity.

  9. Reconnaissance and economic geology of Copper Mountain metamorphic complex, Owl Creek Mountains, Wyoming

    International Nuclear Information System (INIS)

    Hausel, W.D.

    1983-01-01

    The Copper Mountain metamorphic complex lies within a westerly trending belt of Precambrian exposures known as the Owl Creek Mountains uplift. The metamorphic complex at Copper Mountain is part of a larger complex known as the Owl Creek Mountains greenstone belt. Until more detailed mapping and petrographic studies can be completed, the Copper Mountain area is best referred to as a complex, even though it has some characteristics of a greestone belt. At least three episodes of Precambrian deformation have affected the supracrustals, and two have disturbed the granites. The final Precambrian deformation event was preceded by a weak thermal event expressed by retrogressive metamorphism and restricted metasomatic alteration. During this event, a second phase of pegmatization was accompanied by hydrothermal solutions. During the Laramide orogeny, Copper Mountain was again modified by deformation. Laramide deformation produced complex gravity faults and keystone grabens. Uranium deposits were formed following major Laramide deformation. The genesis of these deposits is attributable to either the leaching of granites or the leaching of overlying tuffaceous sediments during the Tertiary. Production of metals and industrial minerals has been limited, although some gold, copper, silver, tungsten, beryl, feldspar, and lithium ore have been shipped from Copper Mountain. A large amount of uranium was produced from the Copper Mountain district in the 1950s

  10. Anti-Atlas Mountains, Morocco

    Science.gov (United States)

    2003-01-01

    The Anti-Atlas Mountains of Morocco formed as a result of the collision of the African and Eurasian tectonic plates about 80 million years ago. This collision destroyed the Tethys Ocean; the limestone, sandstone, claystone, and gypsum layers that formed the ocean bed were folded and crumpled to create the Atlas and Anti-Atlas Mountains. In this ASTER image, short wavelength infrared bands are combined to dramatically highlight the different rock types, and illustrate the complex folding. The yellowish, orange and green areas are limestones, sandstones and gypsum; the dark blue and green areas are underlying granitic rocks. The ability to map geology using ASTER data is enhanced by the multiple short wavelength infrared bands, that are sensitive to differences in rock mineralogy. This image was acquired on June 13, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and

  11. Stress and strain patterns, kinematics and deformation mechanisms in a basement-cored anticline: Sheep Mountain Anticline, Wyoming

    Science.gov (United States)

    Amrouch, Khalid; Lacombe, Olivier; Bellahsen, Nicolas; Daniel, Jean-Marc; Callot, Jean-Paul

    2010-02-01

    In order to characterize and compare the stress-strain record prior to, during, and just after folding at the macroscopic and the microscopic scales and to provide insights into stress levels sustained by folded rocks, we investigate the relationship between the stress-strain distribution in folded strata derived from fractures, striated microfaults, and calcite twins and the development of the Laramide, basement-cored Sheep Mountain Anticline, Wyoming. Tectonic data were mainly collected in Lower Carboniferous to Permian carbonates and sandstones. In both rock matrix and veins, calcite twins recorded three different tectonic stages: the first stage is a pre-Laramide (Sevier) layer-parallel shortening (LPS) parallel to fold axis, the second one is a Laramide LPS perpendicular to the fold axis, and the third stage corresponds to Laramide late fold tightening with compression also perpendicular to the fold axis. Stress and strain orientations and regimes at the microscale agree with the polyphase stress evolution revealed by populations of fractures and striated microfaults, testifying for the homogeneity of stress record at different scales through time. Calcite twin analysis additionally reveals significant variations of differential stress magnitudes between fold limbs. Our results especially point to an increase of differential stress magnitudes related to Laramide LPS from the backlimb to the forelimb of the fold possibly in relation with motion of an underlying basement thrust fault that likely induced stress concentrations at its upper tip. This result is confirmed by a simple numerical model. Beyond regional implications, this study highlights the potential of calcite twin analyses to yield a representative quantitative picture of stress and strain patterns related to folding.

  12. Rurality, ethnicity and mountain areas:

    Directory of Open Access Journals (Sweden)

    Anne-Laure Amilhat-Szary

    2009-07-01

    Full Text Available In a Latin American context where indigenous populations have had to wait until the end of the XXth century to recover a certain visibility, the definition of Andean identity is still an issue. In this paper, an analysis of the various steps in a territorially based collective movement provides insights into this identity that was for so long denied or repressed on account of socio-political conditions. The possible re-assertion of “Andeanity” is very complex, as the case study of the “Aymaras Sin Fronteras” (Aymaras without borders movement reveals. In this movement, the territorialisation process is based on the dialectics between its rural, ethnic and mountain (Andean components.Dans un contexte latinoaméricain où les populations autochtones ont dû attendre la fin du XXème siècle pour regagner en visibilité, l’identité andine pose question. Dans cet article, l’analyse des étapes d’une mobilisation collective à base territoriale permet de suivre la  redécouverte d’un ancrage identitaire longtemps nié ou refoulé du fait des conditions socio-politiques. L’affirmation retrouvée de l’ethnicité, voire de l’« andinité » s’avère très  complexe, comme le cas étudié, l’alliance « Aymaras sin Fronteras » (Aymaras sans frontières le révèle. Dans ce cas, le processus de territorialisation se fonde sur une interaction dialectique entre ses composantes rurale, ethnique, et montagnarde (andine.

  13. Precipitation interpolation in mountainous areas

    Science.gov (United States)

    Kolberg, Sjur

    2015-04-01

    Different precipitation interpolation techniques as well as external drift covariates are tested and compared in a 26000 km2 mountainous area in Norway, using daily data from 60 stations. The main method of assessment is cross-validation. Annual precipitation in the area varies from below 500 mm to more than 2000 mm. The data were corrected for wind-driven undercatch according to operational standards. While temporal evaluation produce seemingly acceptable at-station correlation values (on average around 0.6), the average daily spatial correlation is less than 0.1. Penalising also bias, Nash-Sutcliffe R2 values are negative for spatial correspondence, and around 0.15 for temporal. Despite largely violated assumptions, plain Kriging produces better results than simple inverse distance weighting. More surprisingly, the presumably 'worst-case' benchmark of no interpolation at all, simply averaging all 60 stations for each day, actually outperformed the standard interpolation techniques. For logistic reasons, high altitudes are under-represented in the gauge network. The possible effect of this was investigated by a) fitting a precipitation lapse rate as an external drift, and b) applying a linear model of orographic enhancement (Smith and Barstad, 2004). These techniques improved the results only marginally. The gauge density in the region is one for each 433 km2; higher than the overall density of the Norwegian national network. Admittedly the cross-validation technique reduces the gauge density, still the results suggest that we are far from able to provide hydrological models with adequate data for the main driving force.

  14. Paleomagnetic Results of Permo-Carboniferous Volcanic-sedimentary Strata in Mid-eastern Inner Mongolia, China: Implications for Tectonic Evolution of the Eastern CAOB

    Science.gov (United States)

    Zhang, D.; Huang, B.; Zhao, J.; Bai, Q.; Zhang, Y.; Zhou, T.

    2015-12-01

    There has been hotly debating over the closure time of the eastern Paleo-Asian Ocean and the tectonic evolution of the eastern CAOB (Central Asian Orogenic Belt) for decades. To better puzzle out this controversy, we carried out a detailed paleomagnetic study on the Permo-Carboniferous volcanic-sedimentary strata in mid-eastern Inner Mongolia, northeast of China. More than 820 samples were collected from 81 sites and titanium-poor magnetite and hematite are proved as the principal magnetic carriers. (1)In Kingan Block, 9 sites of volcanic rocks from Dashizhai Formation (P1) were calculated to get a mean magnetic direction Dg/Ig = 285.5°/77.4°, kg = 68.2, α95 = 6.8° before and Ds/Is = 206.5°/48.2°, ks = 100.8, α95 = 5.5°, N = 9 after bedding correction, which suggests a paleolatitude of 34.5°±5°N. Both the positive fold test and reversal test suggest a pre-folding magnetization and thus may indicate a primary remanence. (2)Three volcanic sections of Baoligaomiao Formation (C3-P1) from Uliastai Passive Margin were sampled and a mean magnetic direction derived from 16 sites is Dg/Ig = 30.1°/31.8°, kg = 16.3, α95 = 9.8° before and Ds/Is = 65.6°/58.1°, ks = 39.8, α95 = 6.1°, N = 16 after bedding correction. The corresponding paleomagnetic pole Plat. /Plong = 43.1° N/186.7°E, A95=8° suggests a paleolatitude of 38.7°±6.3°N. A primary remanence is confirmed by positive fold test. (3) In the northern margin of NCB (North China Block), a ChRM is successfully isolated from 6 sites of basaltic rocks in Elitu Formation (P2) as Dg/Ig = 351.1°/67.2°, kg = 2.1, α95 = 71.8° before and Ds/Is = 351.1°/29.1°, ks = 32.7, α95 = 71.8°, N = 16 after bedding correction, and thus yielded a paleomagnetic pole as Plat. /Plong = 63.1° N/313.5°E, A95=9.5°, which suggests a paleolatitude of 17.2°±7.2°N. A positive fold test and reversal test indicate that the remanence should be primary. The paleomagetic pole of Kingan Block and Uliastai Passive Margin are

  15. Late Carboniferous to Early Permian magmatic pulses in the Uliastai continental margin linked to slab rollback: Implications for evolution of the Central Asian Orogenic Belt

    Science.gov (United States)

    Chai, Hui; Wang, Qingfei; Tao, Jixiong; Santosh, M.; Ma, Tengfei; Zhao, Rui

    2018-05-01

    The Paleo Asian Ocean underwent a protracted closure history during Late Paleozoic. Here we investigate the magmatic evolution during this process based on a detailed study in the Baiyinwula region along the Uliastai continental margin. The major rock types in this area are Late Carboniferous-Early Permian volcanic sequences and coeval intrusions. We identified four stages of magmatic evolution based on the diverse assemblages and their precise isotopic ages. The first stage is represented by andesites with a zircon 206Pb/238U age of ca. 326 ± 12 Ma. These rocks are metaluminous to weakly peraluminous, high-K calc-alkaline, and possess high Na2O/K2O ratios in the range of 1.23 to 2.45. They also display enrichment of large ion lithophile elements (LILE) and depletion of high field strength elements (HFSE), with markedly positive zircon εHf (t) varying from 8.1 to 15.6.The geochemical features of these andesites are similar to those of typical arc volcanic rocks. The second stage includes granodiorites emplaced at 318.6 + 1.8 Ma. The rocks are high-K calc-alkaline with A/CNK values ranging from 0.95 to 1.06, and show enrichment in LILE and depletion in HFSE. They show geochemical affinities to adakites, with high Sr and low Y and Yb contents, indicating magma derivation from thickened lower crust. Zircon grains from these rocks display positive initial εHf (t) values ranging from 11.1 to 14.6 with corresponding two-stage Hf model ages (TDM2) of 394-622 Ma. The third stage consists of syenogranite together with a volcanic suite ranging in composition from rhyolite todacite, which formed during 303.4 ± 1.2 to 285.1 ± 2.2 Ma. They possess elevated silica and alkali contents, high FeOt/MgO and Ga/Al ratios, low Al2O3, MgO and CaO contents, and high Rb, Y, Nb, Ce, Zr, Y, and Ga contents, strong negative Ba, Sr and Eu anomalies, showing I- to A-type granitic affinities. Zircons in these rocks show elevated Hf isotopic compositions (εHf (t) = 9.9 to 14.6) with TDM2

  16. Research in karst aquifers developed in high-mountain areas combining KARSYS models with springs discharge records. Picos de Europa, Spain

    Science.gov (United States)

    Ballesteros, Daniel; Meléndez, Mónica; Malard, Arnauld; Jiménez-Sánchez, Montserrat; Heredia, Nemesio; Jeannin, Pierre-Yves; García-Sansegundo, Joaquín

    2014-05-01

    The study of karst aquifers developed in high-mountain areas is quite complex since the application of many techniques of hydrogeology in these areas is difficult, expensive, and requires many hours of field work. In addition, the access to the study area is usually conditioned by the orography and the meteorological conditions. A pragmatic approach to study these aquifers can be the combination of geometric models of the aquifer with the monitoring of the discharge rate of springs and the meteorological records. KARSYS approach (Jeannin et al. 2013) allows us to elaborate a geometric model of karst aquifers establishing the boundaries of the groundwater bodies, the main drainage axes and providing evidences of the catchment delineation of the springs. The aim of this work is to analyse the functioning of the karst aquifer from the western and central part of the Picos de Europa Mountains (Spain) combining the KARSYS approach, the discharge record from two springs and the meteorological records (rain, snow and temperature). The Picos de Europa (North Spain) is a high-mountains area up to 2.6 km altitude with 2,500 mm/year of precipitations. The highest part of these mountains is covered by snow four to seven months a year. The karst aquifer is developed in Carboniferous limestone which is strongly compartmentalized in, at least, 17 groundwater bodies. The method of work includes: 1) the elaboration of a hydrogeological 3D model of the geometry of the karst aquifers by KARSYS approach, 2) the definition of the springs catchment areas based on the hydrogeological 3D model, 3) the selection of two representative springs emerging from the aquifers to study it, 4) the continuous monitoring of water levels in two karst springs since October 2013, 5) the transformation of the water level values to flow values using height-stream relation curves constructed by measures of the spring discharge, and 5) the comparison of the spring discharge rate records and meteorological

  17. A new network on mountain geomorphosites

    Science.gov (United States)

    Giusti, Christian

    2013-04-01

    Since about two decades, the value of geoheritage in mountain areas has been re-discovered in various parts of the Alps (Reynard et al., 2010) and other mountain ranges, and various initiatives (protection of sites worthy of protection, inventories of geomorphosites, geotourist promotion, creation of geoparks, etc.) to conserve or promote mountain geoheritage have been developed. As mountains are recognized as natural areas with a very high geodiversity, and at the same time as areas with a great potential for the development of soft tourism, a new Network on Mountain Geomorphosites was created in October 2012 in conclusion to a workshop organized by the University of Lausanne (Switzerland). The Network is open to all researchers active in geoheritage, geoconservation and geotourism studies in mountain areas. For the first years research will focus on three main issues: - Geoheritage and natural processes: Mountains are very sensitive areas where climate change impacts are very acute and where active geomorphological processes rapidly modify landscapes. It is hypothesized that geoheritage will be highly impacted by global change in the future. Nevertheless, at the moment, very little research is carried out on the evolution of landforms recognized as geoheritage and no specific management measures have been developed. Also, the tourist activities related to geoheritage, especially the trails developed to visit geomorphosites, are sensitive to geomorphological processes in mountain areas in a context of global change, and need, therefore, to be better addressed by geomorphologists. - Geotourism: During the last two decades numerous initiatives have developed geotourism in mountain areas. Nevertheless, studies addressing issues such as the needs of the potential public(s) of geotourism, the evaluation of the quality of the geotourist products developed by scientists and/or local authorities, and the assessment of the economic benefits of geotourism for the regional

  18. Composition of microbial communities in aerosol, snow and ice samples from remote glaciated areas (Antarctica, Alps, Andes)

    Science.gov (United States)

    Elster, J.; Delmas, R. J.; Petit, J.-R.; Řeháková, K.

    2007-06-01

    Taxonomical and ecological analyses were performed on micro-autotrophs (cyanobacteria and algae together with remnants of diatom valves), micro-fungi (hyphae and spores), bacteria (rod, cocci and red clusters), yeast, and plant pollen extracted from various samples: Alps snow (Mt. Blank area), Andean snow (Illimani, Bolivia), Antarctic aerosol filters (Dumont d'Urville, Terre Adélie), and Antarctic inland ice (Terre Adélie). Three methods for ice and snow sample's pre-concentration were tested (filtration, centrifugation and lyophilisation). Afterwards, cultivation methods for terrestrial, freshwater and marine microorganisms (micro-autotrophs and micro-fungi) were used in combination with liquid and solid media. The main goal of the study was to find out if micro-autotrophs are commonly transported by air masses, and later stored in snow and icecaps around the world. The most striking result of this study was the absence of culturable micro-autotrophs in all studied samples. However, an unusual culturable pigmented prokaryote was found in both alpine snow and aerosol samples. Analyses of many samples and proper statistical analyses (PCA, RDA- Monte Carlo permutation tests) showed that studied treatments highly significantly differ in both microbial community and biotic remnants composition F=9.33, p=0.001. In addition, GLM showed that studied treatments highly significantly differ in numbers of categories of microorganisms and remnants of biological material F=11.45, p=0.00005. The Antarctic aerosol samples were characterised by having red clusters of bacteria, the unusual prokaryote and yeasts. The high mountain snow from the Alps and Andes contained much more culturable heterotrophs. The unusual prokaryote was very abundant, as were coccoid bacteria, red clusters of bacteria, as well as yeasts. The Antarctic ice samples were quite different. These samples had higher numbers of rod bacteria and fungal hyphae. The microbial communities and biological remnants of

  19. Understanding Hydrological Processes in Variable Source Areas in the Glaciated Northeastern US Watersheds under Variable Climate Conditions

    Science.gov (United States)

    Steenhuis, T. S.; Azzaino, Z.; Hoang, L.; Pacenka, S.; Worqlul, A. W.; Mukundan, R.; Stoof, C.; Owens, E. M.; Richards, B. K.

    2017-12-01

    The New York City source watersheds in the Catskill Mountains' humid, temperate climate has long-term hydrological and water quality monitoring data It is one of the few catchments where implementation of source and landscape management practices has led to decreased phosphorus concentration in the receiving surface waters. One of the reasons is that landscape measures correctly targeted the saturated variable source runoff areas (VSA) in the valley bottoms as the location where most of the runoff and other nonpoint pollutants originated. Measures targeting these areas were instrumental in lowering phosphorus concentration. Further improvements in water quality can be made based on a better understanding of the flow processes and water table fluctuations in the VSA. For that reason, we instrumented a self-contained upland variable source watershed with a landscape characteristic of a soil underlain by glacial till at shallow depth similar to the Catskill watersheds. In this presentation, we will discuss our experimental findings and present a mathematical model. Variable source areas have a small slope making gravity the driving force for the flow, greatly simplifying the simulation of the flow processes. The experimental data and the model simulations agreed for both outflow and water table fluctuations. We found that while the flows to the outlet were similar throughout the year, the discharge of the VSA varies greatly. This was due to transpiration by the plants which became active when soil temperatures were above 10oC. We found that shortly after the temperature increased above 10oC the baseflow stopped and only surface runoff occurred when rainstorms exceeded the storage capacity of the soil in at least a portion of the variable source area. Since plant growth in the variable source area was a major variable determining the base flow behavior, changes in temperature in the future - affecting the duration of the growing season - will affect baseflow and

  20. DANGERS AND SAFETY MEASURES IN A MOUNTAIN

    Directory of Open Access Journals (Sweden)

    Jovica Petković

    2013-07-01

    Full Text Available Mountaineering and everything that is connected with it is a sport with con¬tro¬lled risk. Mountaineers, alpinists, climbers, cavers and all the others who visit and sojourn in mountains are faced with many risks and dangers, which are caused by na¬ture and also by their own mistakes. The dangers in the mountains, like dangers in any other environment, are mainly predictable, so it is best to deal with them with good esti¬mation, knowledge and skill. One has to be aware of his surroundings – the moun¬tain, to respect it and to know what is dangerous and how much it is dangerous at any moment. The organization of the mountaineering expeditions and leadership per¬haps re¬present the highest level of security control. To develop skills for organizing and lead¬ing a group means to ensure the safety of the entire group – to work pre¬ven¬ti¬ve¬ly at the level of the entire group, not only at the level of an individual. The success of the enti¬re group as well as safety depends on the organization and leadership.

  1. Mountain goat abundance and population trends in the Olympic Mountains, Washington, 2011

    Science.gov (United States)

    Jenkins, Kurt; Happe, Patricia; Griffin, Paul C.; Beirne, Katherine; Hoffman, Roger; Baccus, William

    2011-01-01

    We conducted an aerial helicopter survey between July 18 and July 25, 2011, to estimate abundance and trends of introduced mountain goats (Oreamnos americanus) in the Olympic Mountains. The survey was the first since we developed a sightability correction model in 2008, which provided the means to estimate the number of mountain goats present in the surveyed areas and not seen during the aerial surveys, and to adjust for undercounting biases. Additionally, the count was the first since recent telemetry studies revealed that the previously defined survey zone, which was delineated at lower elevations by the 1,520-meter elevation contour, did not encompass all lands used by mountain goats during summer. We redefined the lower elevation boundary of survey units before conducting the 2011 surveys in an effort to more accurately estimate the entire mountain goat population. We surveyed 39 survey units, comprising 39 percent of the 59,615-hectare survey area. We estimated a mountain goat population of 344±44 (standard error, SE) in the expanded survey area. Based on this level of estimation uncertainty, the 95-percent confidence interval ranged from 258 to 430 mountain goats at the time of the survey. To permit comparisons of mountain goat populations between the 2004 and 2011 surveys, we recomputed population estimates derived from the 2004 survey using the newly developed bias correction methods, and we computed the 2004 and 2011 surveys based on comparable survey zone definitions (for example, using the boundaries of the 2004 survey). The recomputed estimates of mountain goat populations were 217±19 (SE) in 2004 and 303±41(SE) in 2011. The difference between the current 2011 population estimate (344±44[SE]) and the recomputed 2011 estimate (303±41[SE]) reflects the number of mountain goats counted in the expanded lower elevation portions of the survey zone added in 2011. We conclude that the population of mountain goats has increased in the Olympic Mountains at

  2. Morphological characteristics of overdeepenings in high-mountain glacier beds

    Science.gov (United States)

    Haeberli, Wilfried; Cochachin, Alejo; Fischer, Urs; Giráldez, Claudia; Linsbauer, Andreas; Salazar, Cesar

    2014-05-01

    Overdeepenings, i.e. closed topographic depressions with adverse slopes in the flow direction, are characteristic for glacier beds and glacially sculpted landscapes. Besides their importance as geomorphological landforms, groundwater bodies and sedimentary archives, they are of increasing interest in relation to climate-induced lake formation in de-glaciating landscapes and to depth erosion under ice age conditions in connection with the long-term safety of radioactive waste repositories in some mid-latitude countries. Quantitative predictions of their shape, distribution and conditions of occurrence, however, remain difficult. One major problem thereby relates to the still unsatisfactory treatment in glacier erosion theory of sediment evacuation at glacier beds, especially by subglacial meltwater. An alternative way of searching for realistic/empirical quantitative estimates is, therefore, to analyse the geometry of well-documented overdeepenings. The present study attempts to do this by combining statistical analyses of (a) detailed bathymetries from recently exposed lakes in the Peruvian Andes, (b) numerous bed overdeepenigs below still existing glaciers of the Swiss Alps and the Himalaya-Karakoram region modelled with a robust shear stress approximation linking surface slope to ice thickness at high resolution, and (c, for comparison) reconstructed overdeepenings produced by ice age glaciers in the Swiss Plateau based on numerous drillings and geophysical soundings. The sample of (a) has the advantage that geometries are exactly measured and only subject to young/small sedimentation effects. Sample (b) allows for a comparison with a modern model calculation and with known glacier characteristics. Sample (c) may provide some insights into the question how safely results from high mountain topography can be transferred to sites with markedly different topographic, climatic and glaciological controls (cold-arid lowland). Where possible, mean and maximum values of

  3. Pleistocene glacial refugia across the Appalachian Mountains and coastal plain in the millipede genus Narceus: Evidence from population genetic, phylogeographic, and paleoclimatic data

    Science.gov (United States)

    Walker, Matt J; Stockman, Amy K; Marek, Paul E; Bond, Jason E

    2009-01-01

    Background Species that are widespread throughout historically glaciated and currently non-glaciated areas provide excellent opportunities to investigate the role of Pleistocene climatic change on the distribution of North American biodiversity. Many studies indicate that northern animal populations exhibit low levels of genetic diversity over geographically widespread areas whereas southern populations exhibit relatively high levels. Recently, paleoclimatic data have been combined with niche-based distribution modeling to locate possible refugia during the Last Glacial Maximum. Using phylogeographic, population, and paleoclimatic data, we show that the distribution and mitochondrial data for the millipede genus Narceus are consistent with classical examples of Pleistocene refugia and subsequent post-glacial population expansion seen in other organismal groups. Results The phylogeographic structure of Narceus reveals a complex evolutionary history with signatures of multiple refugia in southeastern North America followed by two major northern expansions. Evidence for refugial populations were found in the southern Appalachian Mountains and in the coastal plain. The northern expansions appear to have radiated from two separate refugia, one from the Gulf Coastal Plain area and the other from the mid-Atlantic coastal region. Distributional models of Narceus during the Last Glacial Maximum show a dramatic reduction from the current distribution, with suitable ecological zones concentrated along the Gulf and Atlantic coastal plain. We found a strong correlation between these zones of ecological suitability inferred from our paleo-model with levels of genetic diversity derived from phylogenetic and population estimates of genetic structuring. Conclusion The signature of climatic change, during and after the Pleistocene, on the distribution of the millipede genus Narceus is evident in the genetic data presented. Niche-based historical distribution modeling strengthens the

  4. ESR dating of glacial tills of Baishuihe river on the southern slope of Lenglongling in the eastern part of Qilian Mountains

    International Nuclear Information System (INIS)

    Zhao Jingdong; Zhou Shangzhe; Shi Zhengtao; Zhang Shiqiang; Cui Jianxin; Xu Liubing; Ye Yuguang

    2001-01-01

    Baishuihe River is a tributary of Datong River, located on the southern slope of Lenglongling in the eastern part of the Qilian Mountains. An integral end till remains at the entrance of the valley. There is a push moraine in the till section. Three samples were derived from this section. Two samples were collected at the front of the push moraine and another sample (near the push moraine) collected from the rear of it, ESR ages were 73.0 ka, 55.8 ka, 36.7 ka respectively. The ESR ages being consistent with the relationship of deposits. The ages before the push moraine were correlated to the deep-sea oxygen isotope stage 4 within 10% deviation. Based on them, the authors could determine the till before the push moraine were formed in the early period of Last Glaciation. Comparing the ESR age of LS-5 with the results of previous 14 C, the authors found that the ESR age was older. Through the error correction, the authors concluded: the existing push moraine distorted the till around it, mixing the super-glacial till, englacial till and subglacial till together. The authors considered: the main reason influencing the ESR age was that the englacial till and the subglacial till were not exposed completely before they deposited. Although the result of LS-5 was older than the previous 14 C, combining the ESR age and the relationship of deposit and the existing 14 C ages, the authors inferred that the rear of the push moraine was deposited in the later period of the last glaciation and was correlated to the deep-sea oxygen isotope stage 2. At the same time, the conclusion once again proved the previous scholars' conclusion. This shows the ESR technique may be applied to glacial till dating

  5. Assessment of Appalachian basin oil and gas resources: Carboniferous Coal-bed Gas Total Petroleum System: Chapter G.1 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    Science.gov (United States)

    Milici, Robert C.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    The Carboniferous Coal-bed Gas Total Petroleum System, which lies within the central and southern Appalachian basin, consists of the following five assessment units (AUs): (1) the Pocahontas Basin AU in southern West Virginia, eastern Kentucky, and southwestern Virginia; (2) the Central Appalachian Shelf AU in Tennessee, eastern Kentucky, and southern West Virginia; (3) the East Dunkard (Folded) AU in western Pennsylvania and northern West Virginia; (4) the West Dunkard (Unfolded) AU in Ohio and adjacent parts of Pennsylvania and West Virginia; and (5) the Appalachian Anthracite and Semi-Anthracite AU in Pennsylvania and Virginia. Only two of these assessment units were assessed quantitatively by the U.S. Geological Survey (USGS) in the National Oil and Gas Assessment in 2002. The USGS estimated the Pocahontas Basin AU and the East Dunkard (Folded) AU to contain a mean of about 3.6 and 4.8 trillion cubic feet (TCF) of undiscovered, technically recoverable gas, respectively.

  6. Wildfires in Siberian Mountain Forest

    Science.gov (United States)

    Kharuk, V.; Ponomarev, E. I.; Antamoshkina, O.

    2017-12-01

    The annual burned area in Russia was estimated as 0.55 to 20 Mha with >70% occurred in Siberia. We analyzed Siberian wildfires distribution with respect to elevation, slope steepness and exposure. In addition, wildfires temporal dynamic and latitudinal range were analyzed. We used daily thermal anomalies derived from NOAA/AVHRR and Terra/MODIS satellites (1990-2016). Fire return intervals were (FRI) calculated based on the dendrochronology analysis of samples taken from trees with burn marks. Spatial distribution of wildfires dependent on topo features: relative burned area increase with elevation increase (ca. 1100 m), switching to following decrease. The wildfires frequency exponentially decreased within lowlands - highlands transition. Burned area is increasing with slope steepness increase (up to 5-10°). Fire return intervals (FRI) on the southfacing slopes are about 30% longer than on the north facing. Wildfire re-occurrence is decreasing exponentially: 90% of burns were caused by single fires, 8.5% by double fires, 1% burned three times, and on about 0.05% territory wildfires occurred four times (observed period: 75 yr.). Wildfires area and number, as well as FRI, also dependent on latitude: relative burned area increasing exponentially in norward direction, whereas relative fire number is exponentially decreasing. FRI increases in the northward direction: from 80 years at 62°N to 200 years at the Arctic Circle, and to 300 years at the northern limit of closed forests ( 71+°N). Fire frequency, fire danger period and FRI are strongly correlated with incoming solar radiation (r = 0.81 - 0.95). In 21-s century, a positive trend of wildfires number and area observed in mountain areas in all Siberia. Thus, burned area and number of fires in Siberia are significantly increased since 1990th (R2 =0.47, R2 =0.69, respectively), and that increase correlated with air temperatures and climate aridity increases. However, wildfires are essential for supporting fire

  7. Periurban landscapes in mountain areas

    Directory of Open Access Journals (Sweden)

    Nathalie Bertrand

    2009-06-01

    Full Text Available Les mutations des paysages régionaux dues aux pressions urbaines questionnent l’usage du sol. Elles interpellent à la fois des enjeux économiques, sociaux et environnementaux voire spatiaux sous-tendus par l’étalement urbain, l’accroissement des déplacements domicile-travail, le mitage de l’espace. Ces évolutions et dysfonctionnements renvoient à la question de la durabilité du développement des régions, et particulièrement des Alpes, espace contraint géographiquement et objet de nombreuses pressions anthropiques et riche en biotopes remarquables. Cet article est basé sur deux ans de travaux menés par des socio-économistes et des écologues sur les effets sur le paysage et l’environnement de la périurbanisation d’un massif alpin. Nous avons pris en compte l’espace dans les processus environnementaux, économiques ou sociaux. Intrinsèque dans les analyses écologiques, elle a longtemps posé problème à l’économie pour intégrer l’espace comme dimension à part entière des processus économiques. Trois thèmes sont ici développés : l’approche du point de vue du paysage, les problèmes d’échelles spatiales et temporelles, le choix d’indicateurs. Ils demandent de hiérarchiser les questions et de pratiquer le travail en commun. Aller au-delà nécessite de développer une interrogation plus écologique ou plus économique et/ou sociale en quittant de ce fait l’interface pour favoriser des interrogations disciplinaires particulières.Changes in regional landscapes due to urban pressures raise questions regarding land use. They also give rise to economic, social and environmental issues related to urban sprawl, increases in daily commuting, and land consumption. These changes and dysfunctions are ultimately underpinned by the question of sustainable regional development. Mountain regions such as the Alps, with their various outstanding biotopes in a restricted space, are particularly vulnerable.

  8. Yucca Mountain biological resources monitoring program

    International Nuclear Information System (INIS)

    1993-02-01

    The US Department of Energy (DOE) is required by the Nuclear Waste Policy Act of 1982 (as amended in 1987) to study and characterize Yucca Mountain as a potential site for a geologic repository for high-level nuclear waste. During site characterization, the DOE will conduct a variety of geotechnical, geochemical, geological, and hydrological studies to determine the suitability of Yucca Mountain as a potential repository. To ensure that site characterization activities (SCA) do not adversely affect the environment at Yucca Mountain, an environmental program has been implemented to monitor and mitigate potential impacts and ensure activities comply with applicable environmental regulations. This report describes the activities and accomplishments of EG ampersand G Energy Measurements, Inc. (EG ampersand G/EM) during fiscal year 1992 (FY92) for six program areas within the Terrestrial Ecosystem component of the YMP environmental program. The six program areas are Site Characterization Effects, Desert Tortoises, Habitat Reclamation, Monitoring and Mitigation, Radiological Monitoring, and Biological Support

  9. Yucca Mountain Biological Resources Monitoring Program

    International Nuclear Information System (INIS)

    1992-01-01

    The US Department of Energy (DOE) is required by the Nuclear Waste Policy Act of 1982 (as amended in 1987) to study and characterize Yucca Mountain as a possible site for a geologic repository for high-level nuclear waste. During site characterization, the DOE will conduct a variety of geotechnical, geochemical, geological, and hydrological studies to determine the suitability of Yucca Mountain as a repository. To ensure that site characterization activities (SCA) do not adversely affect the Yucca Mountain area, an environmental program has been implemented to monitor and mitigate potential impacts and to ensure that activities comply with applicable environmental regulations. This report describes the activities and accomplishments during fiscal year 1991 (FY91) for six program areas within the Terrestrial Ecosystem component of the YMP environmental program. The six program areas are Site Characterization Activities Effects, Desert Tortoises, Habitat Reclamation, Monitoring and Mitigation, Radiological Monitoring, and Biological Support

  10. Mechanical excavator performance in Yucca Mountain tuffs

    International Nuclear Information System (INIS)

    Ozdemir, L.; Hansen, F.D.

    1991-01-01

    A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests and potentially large-scale laboratory demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs. 3 refs., 2 tabs

  11. Yucca Mountain Biological resources monitoring program

    International Nuclear Information System (INIS)

    1991-01-01

    The US Department of Energy (US DOE) is required by the Nuclear Waste Policy Act of 1982 (as amended in 1987) to study and characterize Yucca Mountain as a possible site for a geological repository for high-level radioactive waste. To ensure site characterization activities do not adversely affect the Yucca Mountain area, an environmental program, the Yucca Mountain Biological Resources Monitoring Program, has been implemented monitor and mitigate environmental impacts and to ensure activities comply with applicable environmental laws. Potential impacts to vegetation, small mammals, and the desert tortoise (an indigenous threatened species) are addressed, as are habitat reclamation, radiological monitoring, and compilation of baseline data. This report describes the program in Fiscal Years 1989 and 1990. 12 refs., 4 figs., 17 tabs

  12. Mechanical excavator performance in Yucca Mountain tuffs

    International Nuclear Information System (INIS)

    Ozdemir, L.; Hansen, F.D.

    1991-01-01

    A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests, and potentially large-scale lab. demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well-quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs

  13. A case of Rocky Mountain spotted fever.

    Science.gov (United States)

    Rubel, Barry S

    2007-01-01

    Rocky Mountain spotted fever is a serious, generalized infection that is spread to humans through the bite of infected ticks. It can be lethal but it is curable. The disease gets its name from the Rocky Mountain region where it was first identified in 1896. The fever is caused by the bacterium Rickettsia rickettsii and is maintained in nature in a complex life cycle involving ticks and mammals. Humans are considered to be accidental hosts and are not involved in the natural transmission cycle of this pathogen. The author examined a 47-year-old woman during a periodic recall appointment. The patient had no dental problems other than the need for routine prophylaxis but mentioned a recent problem with swelling of her extremities with an accompanying rash and general malaise and soreness in her neck region. Tests were conducted and a diagnosis of Rocky Mountain spotted fever was made.

  14. Skarn-mineralized porphyry adakites in the Harlik arc at Kalatage, E. Tianshan (NW China): Slab melting in the Devonian-early Carboniferous in the southern Central Asian Orogenic Belt

    Science.gov (United States)

    Mao, Qigui; Yu, Mingjie; Xiao, Wenjiao; Windley, Brian F.; Li, Yuechen; Wei, Xiaofeng; Zhu, Jiangjian; Lü, Xiaoqiang

    2018-03-01

    The geodynamic control of mineralization in the accretionary evolution of the Central Asian Orogenic Belt (CAOB) has long been controversial. Here we report new field, geochemical and geochronological data on recently defined porphyry and skarn-type ore deposits (Devonian-Early Carboniferous) in the Kalatage area in the middle of the Harlik-Dananhu arc, Eastern Tianshan, NW China in the southern CAOB, with the aim of better understanding the accretionary tectonics and genesis of porphyry and skarn-type mineralization. The Yudai porphyry Cu-(Au) deposits and the Xierqu skarn Cu-Fe-(Au) deposits are closely associated with Middle Devonian adakitic diorite porphyries (382-390 Ma), which are calc-alkaline and characterized by high Na2O/K2O ratios and Sr contents (310-1020 ppm), strong depletion of HREE (e.g., Yb = 0.80-1.44 ppm) and Y (7.68-14.50 ppm), and all enriched in Rb, Sr, Ba, K and depleted in Nb and Ti. They are characterized by distinctive Eu positive anomalies, high Na2O contents and MORB-like Sr and Nd isotope signatures (high εNd(t) = +6.1 to +7.0 and low (87Sr/86Sr)i = 0.70412-0.70462). These adakites most likely formed by melting of a young/hot subducted oceanic slab, and adakites in general are important carriers of porphyry Cu ± (Au) deposits. Early Carboniferous adakites in the Tuwu area south of Kalatage are known to have similar features. Therefore, skarn-mineralized porphyry adakites get younger from north to south, suggesting southward migration of the Harlik-Dananhu arc from 390 Ma to 322 Ma. These data indicate that partial melting of hot (and/or young) oceanic crustal slabs were an important mechanism of accretionary crustal growth and mineralization in the southern CAOB.

  15. Glacier evolution in high-mountain Asia under stratospheric sulfate aerosol injection geoengineering

    Directory of Open Access Journals (Sweden)

    L. Zhao

    2017-06-01

    Full Text Available Geoengineering by stratospheric sulfate aerosol injection may help preserve mountain glaciers by reducing summer temperatures. We examine this hypothesis for the glaciers in high-mountain Asia using a glacier mass balance model driven by climate simulations from the Geoengineering Model Intercomparison Project (GeoMIP. The G3 and G4 schemes specify use of stratospheric sulfate aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP 4.5 scenario for the 50 years between 2020 and 2069, and for a further 20 years after termination of geoengineering. We estimate and compare glacier volume loss for every glacier in the region using a glacier model based on surface mass balance parameterization under climate projections from three Earth system models under G3, five models under G4, and six models under RCP4.5 and RCP8.5. The ensemble projections suggest that glacier shrinkage over the period 2010–2069 is equivalent to sea-level rise of 9.0 ± 1.6 mm (G3, 9.8 ± 4.3 mm (G4, 15.5 ± 2.3 mm (RCP4.5, and 18.5 ± 1.7 mm (RCP8.5. Although G3 keeps the average temperature from increasing in the geoengineering period, G3 only slows glacier shrinkage by about 50 % relative to losses from RCP8.5. Approximately 72 % of glaciated area remains at 2069 under G3, as compared with about 30 % for RCP8.5. The widely reported reduction in mean precipitation expected for solar geoengineering is unlikely to be as important as the temperature-driven shift from solid to liquid precipitation for forcing Himalayan glacier change. The termination of geoengineering at 2069 under G3 leads to temperature rise of about 1.3 °C over the period 2070–2089 relative to the period 2050-2069 and corresponding increase in annual mean glacier volume loss rate from 0.17 to 1.1 % yr−1, which is higher than the 0.66 % yr−1 under RCP8.5 during 2070–2089.

  16. Nuclear waste disposal: Gambling on Yucca Mountain

    International Nuclear Information System (INIS)

    Ginsburg, S.

    1995-01-01

    This document describes the historical aspects of nuclear energy ,nuclear weapons usage, and development of the nuclear bureaucracy in the United States, and discusses the selection and siting of Yucca Mountain, Nevada for a federal nuclear waste repository. Litigation regarding the site selection and resulting battles in the political arena and in the Nevada State Legislature are also presented. Alternative radioactive waste disposal options, risk assessments of the Yucca Mountain site, and logistics regarding the transportation and storage of nuclear waste are also presented. This document also contains an extensive bibliography

  17. The mountains influence on Turkey Climate

    International Nuclear Information System (INIS)

    Sensoy, Serhat

    2004-01-01

    Since the Black sea mountains at the north of the country and the Taurus mountains in the south lay parallel to the seashore and rise very sharply rain clouds can not penetrate to the internal part of the country. Rain clouds drops most of their water on the slopes opposite the sea. As rain clouds pass over the mountains and reach Central Anatolia they have no significant capability of rain. For this reason, the Central Anatolia does not have very much precipitation. The difference between the rates of precipitation on the inner and outer slopes seems to be effective on the expansion of plants. For example, there is a subtropical climate prevailing on the Black sea shore between Sinop and Batum where precipitation is more than 1000-2000 mm yearly. Going from Sinop to the mouth of the Sakarya River the rate of precipitation goes down to 800-1250 mm in a year. Running from the Sakarya River to the western area covering Thrace the climate seems to be continental, and in the area dominant plant cover is of the Mediterranean type. Since the succession of the mountains in Western Anatolia lay perpendicular to the seashore, rain clouds penetrate towards the inner regions for about 400 km. The continental climate with long, dry and summer affects this area. In the Eastern region of Anatolia, since the elevation of the mountains exceeds 2500-3000 m, valleys are disorderly scattered and located at high elevations, and the northern Black sea mountains and Caucasian mountains hold the rain clouds, the area is effected by the continental climate with long and very cold winters. Consequently precipitation at the lgdir River goes down to 300 mm while it is 500-800 mm in most of areas and 1000-1500 mm in some regions towards northern Mu and Bingol provinces. As mentioned above, high mountains, which hold rain clouds, surround the Central Anatolia, which has caused drought in this region. In the central Anatolia covering Afyon, Eski hir, Ankara, Qankiri, Qorum, Amasya, Kayseri

  18. Succession status on mountain farms in Slovenia

    Directory of Open Access Journals (Sweden)

    Boštjan Kerbler-Kefo

    2008-12-01

    Full Text Available This paper is based on the hypothesis that the offi cial statistical data does not refl ect actual succession status on mountain farms in Slovenia and also on Slovene farms in general, since the census criteria defi ning succession are still incomplete. With the purpose of confi rming our assumption, we formulated more accurate criteria and also determined as to what is the real status of succession on mountain farms in Slovenia. It has proved to be more favourable, than it is presented by the offi cial statistics.

  19. Risk management among mountain bikers in selected clubs in ...

    African Journals Online (AJOL)

    Risk management among mountain bikers in selected clubs in Malaysia. ... Journal of Fundamental and Applied Sciences. Journal Home · ABOUT ... is more risky. Keywords: mountain biking, risk management, event management, Malaysia ...

  20. MOUNTAIN TOURISM INTERCONNECTIONS. VARIATION OF MOUNTAIN TOURIST FLOW IN SUCEAVA COUNTY

    Directory of Open Access Journals (Sweden)

    George CHEIA

    2013-12-01

    Full Text Available Mountain tourism, in addition to one of the most common types of tourism, is generated by a complex of factors and at the same time, triggers a series of processes involving tourism phenomenon, especially the environment where it is taking place. This paper aims to discuss some of these causal factors, and the relationship between this type of tourism and the tourist area itself (1. By using SPSS analytical methods , it can be practically demonstrated the impact of mountain tourist flow in spas (2 and mountain resorts (3 in Suceava county.

  1. Geomorphological evidence of warm-humid and cold-dry glaciations in the dry western Cordillera of the tropical Peruvian Andes

    Science.gov (United States)

    Mächtle, B.; Hein, A. S.; Dunai, T.; Eitel, B.

    2012-04-01

    The western Cordillera of the Andes (14°30'S, 74°W) is characterized by high altitudes, strong radiation and semi-arid conditions. Therefore, glacial processes and resulting landforms differ markedly from these of the outer-tropics. However, under sub-arctic conditions similar glacial landforms occur. This congruence can be explained by comparable environmental conditions, which determine the dynamics of ice flow, glacial erosion, debris production as well as moraine deposition. Outside the higher latitudes, typical sub-arctic glacial landforms as controlled moraines and trimline moraines (Evans 2009, Ó Cofaigh et al. 2005) remained undescribed until now. These landforms result from polythermal or cold-basal ice flow, respectively, which is typical for polar conditions. Beside this, we also found steep lateral moraines, which give evidence of increased ice thickness, debris production and deposition and warm-basal ice flow, which is conceivable only for alpine-type valley glaciers. Striations of the bedrock give evidence of accompanied basal erosion. Coexisting trimline moraines and steep lateral moraines rule out the influence of topography on ice thickness and the resulting thermal regime. Therefore, we match the different moraine types to changes in ice thickness, which was controlled by considerable precipitation changes during the last glaciation. An erroneous classification of the observed boulder associations as trimline moraine due to selective erosion after deposition can be excluded due to general arid conditions, slow weathering and the chronological proximity of only a few millennia between both landforms, determined from cosmogenic nuclides. Therefore, the occurrence of different thermal regimes gives evidence of considerable changes in precipitation during the last glaciation - but furthermore requires an associated change in the thermal conditions to explain the very close spatial position of both ice margins. Changes in ice volume must have

  2. Reconstructing Southern Greenland Ice Sheet History During the Plio-Pleistocene Intensification of Northern Hemisphere Glaciation: Insights from IODP Site U1307

    Science.gov (United States)

    Blake-Mizen, K. R.; Hatfield, R. G.; Carlson, A. E.; Walczak, M. H.; Stoner, J. S.; Xuan, C.; Lawrence, K. T.; Bailey, I.

    2017-12-01

    Should it melt entirely, the Greenland Ice Sheet (GrIS) has the potential to raise global sea-level by 7 metres. With the Arctic continuing to warm at a remarkable rate, to better understand how the GrIS will respond to future anthropogenically-induced climate change we must constrain its natural variability in the geological past. In this regard, much uncertainty exists surrounding its pre-Quaternary history; particularly during the mid-Piacenzian warm period (mPWP; 3.3-3.0 Ma) - widely considered an analogue for near-future equilibrium climate with modern atmospheric CO2 levels and elevated temperatures relative to today - and the late Pliocene/early Pleistocene onset of widespread Northern Hemisphere glaciation (NHG, 2.7 Ma). GrIS reconstructions for these intervals have been largely hampered by a lack of well-dated, high-resolution records from suitable sites. To address this, we present new high-resolution, multi-proxy records from IODP Site U1307, a North Atlantic marine sediment core recovered from the Eirik Drift just south of Greenland. Generation of a new high-resolution relative palaeointensity (RPI)-based age-model - representing the first of its kind for high-latitude sediments deposited during NHG - has enabled strong orbital age control. Our ice-rafted debris (IRD) record confirms a 2.72 Ma initiation of major southern GrIS marine-terminating glaciations, which appear to persist even through interglacial periods up to at least 2.24 Ma. XRF-scanning and IRD evidence suggests, however, that an ephemeral ice-cap of likely considerable size persisted on southern Greenland prior to the mPWP. These data, together with the analysed provenance of individual IRD, indicate marine-based GrIS margins extended southward over the NHG interval and only occurred on Greenland's southern tip from 2.7 Ma. Despite a large increase in the deposition of GrIS-derived IRD from this time, bulk sedimentation rates and magnetic grain-size dropped significantly, implying that

  3. The Geologic Story of the Uinta Mountains

    Science.gov (United States)

    Hansen, Wallace R.

    1969-01-01

    The opening of the West after the Civil War greatly stimulated early geologic exploration west of the 100th Meridian. One of the areas first studied, the Uinta Mountains region, gained wide attention as a result of the explorations of three Territorial Surveys, one headed by John Wesley Powell, one by Clarence King, and one by Ferdinand V. Hayden. Completion of the Union Pacific Railroad across southern Wyoming 100 years ago, in 1869, materially assisted geologic exploration, and the railheads at Green River and Rock Springs greatly simplified the outfitting of expeditions into the mountains. The overlap of the Powell, King, and Hayden surveys in the Uinta Mountains led to efforts that were less concerted than competitive and not without acrimony. Many parts of the area were seen by all three parties at almost the same time. Duplication was inevitable, of course, but all three surveys contributed vast quantities of new knowledge to the storehouse of geology, and many now-basic concepts arose from their observations. Powell's area of interest extended mainly southward from the Uinta Mountains to the Grand Canyon, including the boundless plateaus and canyons of southern Utah and northern Arizona. King's survey extended eastward from the High Sierra in California to Cheyenne, Wyoming, and encompassed a swath of country more than 100 miles wide. Hayden's explorations covered an immense region of mountains and basins from Yellowstone Park in Wyoming southeast throughout most of Colorado. Powell first entered the Uinta Mountains in the fall of 1868, having traveled north around the east end of the range from the White River country to Green River, Wyoming, then south over a circuitous route to Flaming Gorge and Browns Park, and finally back to the White River, where he spent the winter. In 1869, after reexamining much of the area visited the previous season, Powell embarked on his famous 'first boat trip' down the Green and Colorado Rivers. This trip was more exploratory

  4. Eastern Arc Mountains and their national and global importance ...

    African Journals Online (AJOL)

    The Eastern Arc Mountains comprise a chain of separate mountain blocks running from southern Kenya through Tanzania in a crescent or arc shape. In Tanzania, the Eastern Arc consists of North and South Pare, East and West Usambaras, Nguru, Ukaguru, Rubeho, Uluguru, Udzungwa and Mahenge Mountains.

  5. Aspen biology, community classification, and management in the Blue Mountains

    Science.gov (United States)

    David K. Swanson; Craig L. Schmitt; Diane M. Shirley; Vicky Erickson; Kenneth J. Schuetz; Michael L. Tatum; David C. Powell

    2010-01-01

    Quaking aspen (Populus tremuloides Michx.) is a valuable species that is declining in the Blue Mountains of northeastern Oregon. This publication is a compilation of over 20 years of aspen management experience by USDA Forest Service workers in the Blue Mountains. It includes a summary of aspen biology and occurrence in the Blue Mountains, and a...

  6. Phytogeography of the tropical north-east African mountains

    Directory of Open Access Journals (Sweden)

    I. Friis

    1983-11-01

    Full Text Available The tropical north-east African mountains are tentatively divided into four phytochoria, the formal rank of which is not defined. The division is based on patterns of distribution and endemism in the region. The recognition of a distinct Afromontane phytochorion is now well established (Chapman & White, 1970; Werger, 1978; White, 1978. However, there is still very little information on the phytogeography of the individual mountains or mountain systems. This study hopes to fill a little of the gap by analysing distribution patterns and patterns of endemism in the flora of the tropical north-east African mountains. The north-east African mountain system is the largest in tropical Africa (see e.g. map in White, 1978. At the core of this system is the large Ethiopian massif, around which are located various mountains and mountain chains. These include the Red Sea Hills in the Sudan, the mountain chain in northern Somalia, the south-west Arabian mountains, and the Imatong mountains of south-east Sudan. The latter are often referred to the East African mountain system (White, 1978 but. as I will point out later, they also have a close connection with the south-west highlands of Ethiopia. The paper presents some results of my study of the mountain flora of tropical north-east Africa, particularly the forest species. Where no source is indicated, the data are from my own unpublished studies.

  7. Hydrologeologic characteristics of faults at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Dickerson, Robert P.

    2001-01-01

    Yucca Mountain is under study as a potential site for underground storage of high-level radioactive waste, with the principle goal being the safe isolation of the waste from the accessible environment. This paper addresses the hydrogeologic characteristics of the fault zones at Yucca Mountain, focusing primarily on the central part of the mountain where the potential repository block is located

  8. Anomalous cold in the Pangaean tropics

    Science.gov (United States)

    Soreghan, G.S.; Soreghan, M.J.; Poulsen, C.J.; Young, R.A.; Eble, C.F.; Sweet, D.E.; Davogustto, O.C.

    2008-01-01

    The late Paleozoic archives the greatest glaciation of the Phanerozoic. Whereas high-latitude Gondwanan strata preserve widespread evidence for continental ice, the Permo-Carboniferous tropics have long been considered analogous to today's: warm and shielded from the highlatitude cold. Here, we report on glacial and periglacial indicators that record episodes of freezing continental temperatures in western equatorial Pangaea. An exhumed glacial valley and associated deposits record direct evidence for glaciation that extended to low paleoelevations in the ancestral Rocky Mountains. Furthermore, the Permo-Carboniferous archives the only known occurrence of widespread tropical loess in Earth's history; the volume, chemistry, and provenance of this loess(ite) is most consistent with glacial derivation. Together with emerging indicators for cold elsewhere in low-latitude Pangaea, these results suggest that tropical climate was not buffered from the high latitudes and may record glacial-interglacial climate shifts of very large magnitude. Coupled climate-ice sheet model simulations demonstrate that low atmospheric CO2 and solar luminosity alone cannot account for such cold, and that other factors must be considered in attempting to explain this 'best-known' analogue to our present Earth. ?? 2008 The Geological Society of America.

  9. Mountain prophecies | IDRC - International Development Research ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2010-12-23

    Dec 23, 2010 ... ... of 2002 as the International Year of Mountains may seem an unlikely choice. ... streams) is begging new questions about how best to preserve this crucial ... In addition, there are the ever-looming hazards of avalanches, ...

  10. Characterize Eruptive Processes at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    D. Krier

    2004-01-01

    The purpose of this scientific analysis report, ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', is to present information about natural volcanic systems and the parameters that can be used to model their behavior. This information is used to develop parameter-value distributions appropriate for analysis of the consequences of volcanic eruptions through a repository at Yucca Mountain. This scientific analysis report provides information to four other reports: ''Number of Waste Packages Hit by Igneous Intrusion'', (BSC 2004 [DIRS 170001]); ''Atmospheric Dispersal and Deposition of Tephra from Potential Volcanic Eruption at Yucca Mountain, Nevada'' (BSC 2004 [DIRS 170026]); ''Dike/Drift Interactions'' (BSC 2004 [DIRS 170028]); ''Development of Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance Assessment of a Geologic Repository at Yucca Mountain, NV'' (BSC 2004 [DIRS 170027], Section 6.5). This report is organized into seven major sections. This section addresses the purpose of this document. Section 2 addresses quality assurance, Section 3 the use of software, Section 4 identifies the requirements that constrain this work, and Section 5 lists assumptions and their rationale. Section 6 presents the details of the scientific analysis and Section 7 summarizes the conclusions reached

  11. Human Infection in Wild Mountain Gorillas

    Centers for Disease Control (CDC) Podcasts

    This podcast discusses a study about the transmission of Human Metapneumovirus Infection to wild mountain gorillas in Rwanda in 2009, published in the April 2011 issue of Emerging Infectious Diseases. Dr. Ian Lipkin, Director of the Center for Infection and Immunity and Dr. Gustavo Palacios, investigator in the Center of Infection & Immunity share details of this study.

  12. Determination of characteristics maximal runoff Mountain Rivers

    African Journals Online (AJOL)

    Ovcharuk V and Todorova O

    Odessa State Environmental University, Ukraine. Received: 03 December 2015 / Accepted: 23 April 2016 / Published online: 01 May 2016. ABSTRACT. This article has been examined maximum runoff of the rivers of the Crimean Mountains. The rivers flow through the western and eastern part of the northern slope Crimean ...

  13. The mountain Cer: Potentials for tourism development

    Directory of Open Access Journals (Sweden)

    Grčić Mirko D.

    2003-01-01

    Full Text Available In northwest of Serbia in the meridians directions an elongated mountain range of Cer with Iverak and Vlašić stretches itself. On the north it goes down to Mačva and Posavina, on the west to Podrinje, on the east to the valley of Kolubara, on the south to the basins and valleys of Jadar and upper Kolubara, which separate it from the mountains of Valjevo and Podrinje area. Cer mountain offers extremely good condition for development of eco-tourism. The variety of relief with gorgeous see-sites, natural rarities, convenient bio-climatic conditions, significant water resources, forest complexes, medieval fortresses, cultural-historic monuments, richness of flora and fauna, preserved rural environment, traditions and customs of local population, were all neglected as strategic factors in the development of tourism. This mountain’s potentials are quite satisfactory for the needs of eco-tourism, similar to the National Park of Fruška Gora, but it has lacked an adequate ecotourist strategy so far. This study aims to pointing to the potential and possibilities of ecotourist valorization of this mountain.

  14. Mountain biking. Breezy ups and traumatic downs

    International Nuclear Information System (INIS)

    Schueller, G.

    2010-01-01

    For more than two decades the popularity of mountain biking as a national pastime as well as a competitive sport has been undiminished. However, its related risks are not monitored as closely as those, for example, of skiing. The injuries caused by mountain biking are specific and cannot be compared with those caused by other cycling sports. This is due not only to the characteristics of the terrain but also to the readiness to assume a higher risk compared to cycle racing. The particular value of radiology is in the acute trauma setting. Most often musculoskeletal lesions must be examined and digital radiography and MRI are the most useful techniques. Severe trauma of the cranium, face, spine, thorax and abdomen are primarily evaluated with CT, particularly in dedicated trauma centers. Therefore, radiology can play a role in the rapid diagnosis and optimal treatment of the trauma-related injuries of mountain biking. Thus, the unnecessarily high economical damage associated with mountain biking can be avoided. (orig.) [de

  15. [Mountain biking : Breezy ups and traumatic downs].

    Science.gov (United States)

    Schueller, G

    2010-05-01

    For more than two decades the popularity of mountain biking as a national pastime as well as a competitive sport has been undiminished. However, its related risks are not monitored as closely as those, for example, of skiing. The injuries caused by mountain biking are specific and cannot be compared with those caused by other cycling sports. This is due not only to the characteristics of the terrain but also to the readiness to assume a higher risk compared to cycle racing.The particular value of radiology is in the acute trauma setting. Most often musculoskeletal lesions must be examined and digital radiography and MRI are the most useful techniques. Severe trauma of the cranium, face, spine, thorax and abdomen are primarily evaluated with CT, particularly in dedicated trauma centers. Therefore, radiology can play a role in the rapid diagnosis and optimal treatment of the trauma-related injuries of mountain biking. Thus, the unnecessarily high economical damage associated with mountain biking can be avoided.

  16. Mountain Biking with Groups: A "Safe" Activity?

    Science.gov (United States)

    Allen, Terry

    2001-01-01

    A survey mailed to 200 British mountain bike leaders found that rates of cycling accidents and injuries were greater in forests and woodlands than on terrain where a license is required to lead groups of young cyclists. Excessive speed was mentioned in most accidents, coupled with poor use of breaks in many cases. (SV)

  17. Experiments on sediment pulses in mountain rivers

    Science.gov (United States)

    Y. Cui; T. E. Lisle; J. E. Pizzuto; G. Parker

    1998-01-01

    Pulses of sediment can be introduced into mountain rivers from such mechanisms as debris flows, landslides and fans at tributary confluences. These processes can be natural or associated with the activities of humans, as in the case of a pulse created by sediment derived from timber harvest or the removal of a dam. How does the river digest these pulses?

  18. Cerebral blood flow in acute mountain sickness

    DEFF Research Database (Denmark)

    Jensen, J B; Wright, Anne; Lassen, N A

    1990-01-01

    Changes in cerebral blood flow (CBF) were measured using the radioactive xenon technique and were related to the development of acute mountain sickness (AMS). In 12 subjects, ascending from 150 to 3,475 m, CBF was 24% increased at 24 h [45.1 to 55.9 initial slope index (ISI) units] and 4% increased...

  19. Rocky Mountain spotted fever in dogs, Brazil.

    Science.gov (United States)

    Labruna, Marcelo B; Kamakura, Orson; Moraes-Filho, Jonas; Horta, Mauricio C; Pacheco, Richard C

    2009-03-01

    Clinical illness caused by Rickettsia rickettsii in dogs has been reported solely in the United States. We report 2 natural clinical cases of Rocky Mountain spotted fever in dogs in Brazil. Each case was confirmed by seroconversion and molecular analysis and resolved after doxycycline therapy.

  20. Air pollution: worldwide effects on mountain forests

    Science.gov (United States)

    Anne M. Rosenthal; Andrzej Featured: Bytnerowicz

    2004-01-01

    Widespread forest decline in remote areas of the Carpathian Mountains has been linked to air pollution from urban and industrial regions. Besides injuring plant tissues directly, pollutants may deposit to soils and water, drastically changing susceptible ecosystems. Researcher Andrzej Bytnerowicz has developed effective methods for assessing air quality over wildlands...

  1. Mountain Guides: Between Ethics and Socioeconomic Trends

    Science.gov (United States)

    Long, Thierry; Bazin, Damien; Massiera, Bernard

    2012-01-01

    This study analysed mountain guides' representations of environmental responsibility and explored the paradox that these professionals face: using nature as a source of income while trying to preserve it. The study was mainly guided by the philosophical literature on this topic and made use of the concepts of sustainable development and nature.…

  2. Characterize Eruptive Processes at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    D. Krier

    2004-10-04

    The purpose of this scientific analysis report, ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', is to present information about natural volcanic systems and the parameters that can be used to model their behavior. This information is used to develop parameter-value distributions appropriate for analysis of the consequences of volcanic eruptions through a repository at Yucca Mountain. This scientific analysis report provides information to four other reports: ''Number of Waste Packages Hit by Igneous Intrusion'', (BSC 2004 [DIRS 170001]); ''Atmospheric Dispersal and Deposition of Tephra from Potential Volcanic Eruption at Yucca Mountain, Nevada'' (BSC 2004 [DIRS 170026]); ''Dike/Drift Interactions'' (BSC 2004 [DIRS 170028]); ''Development of Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance Assessment of a Geologic Repository at Yucca Mountain, NV'' (BSC 2004 [DIRS 170027], Section 6.5). This report is organized into seven major sections. This section addresses the purpose of this document. Section 2 addresses quality assurance, Section 3 the use of software, Section 4 identifies the requirements that constrain this work, and Section 5 lists assumptions and their rationale. Section 6 presents the details of the scientific analysis and Section 7 summarizes the conclusions reached.

  3. Thunder Mountain School Is Something Special.

    Science.gov (United States)

    NJEA Review, 1979

    1979-01-01

    This article describes Thunder Mountain School, operated year round by the Newton Board of Education under a special use permit granted by the National Park Service. The center includes sports facilities, nature preserves, a farm, and historic sites for use by residential and day students, kindergarten through college. (SJL)

  4. MOUNTAIN NATURAL BIODIVERSITY CONSERVATION IN RUSSIA

    Directory of Open Access Journals (Sweden)

    Arkady Tishkov

    2012-01-01

    Full Text Available High biodiversity and degree of endemism of mountain biota strengthen the mountain regions’ status for the territorial nature conservation. Analysis of the protected areas’ representativeness in various mountain regions of Russia shows some discrepancy between their quantity, square and regional biodiversity originality. The biggest divergences are marked for the Northern Caucasus. The main problems: small area of the protected territories and also cluster character of their spatial distribution, mostly in the high mountains are not supposed to conform with the highest values of the regional flora’s and fauna’s uniqueness, to compensate representativeness of the protected biota and, in anyway, to correspond with the purpose of nature protection frame—the protected territories ecologic network’s forming. The situation in the Urals, Siberia and the Far East seems to be better. The large areas of the protected territories are in general agreement with the high originality of the nature ecosystems. Nevertheless each concrete case needs analysis of the regional biota’s and ecosystems’ biodiversity distribution within the protected areas, including character and (or unique elements of the regional biodiversity to be held. The development of the effectual territorial conservation of mountain regions needs differential approach. The creation of the large representative parcels of nature landscapes in the key-areas has the considerable meaning in the low-developed regions, difficult to access. And well-developed regions have the necessity of nature protected territories’ network development and the planning of the ecological frame’s forming. The territorial biodiversity conservation, including the system of federal, regional and local levels with protective conservation of the rare species has to be combined with ecosystem’s restoration, especially in the zones disturbed by erosion, recreation and military actions. Also it is

  5. Extreme ground motions and Yucca Mountain

    Science.gov (United States)

    Hanks, Thomas C.; Abrahamson, Norman A.; Baker, Jack W.; Boore, David M.; Board, Mark; Brune, James N.; Cornell, C. Allin; Whitney, John W.

    2013-01-01

    Yucca Mountain is the designated site of the underground repository for the United States' high-level radioactive waste (HLW), consisting of commercial and military spent nuclear fuel, HLW derived from reprocessing of uranium and plutonium, surplus plutonium, and other nuclear-weapons materials. Yucca Mountain straddles the western boundary of the Nevada Test Site, where the United States has tested nuclear devices since the 1950s, and is situated in an arid, remote, and thinly populated region of Nevada, ~100 miles northwest of Las Vegas. Yucca Mountain was originally considered as a potential underground repository of HLW because of its thick units of unsaturated rocks, with the repository horizon being not only ~300 m above the water table but also ~300 m below the Yucca Mountain crest. The fundamental rationale for a geologic (underground) repository for HLW is to securely isolate these materials from the environment and its inhabitants to the greatest extent possible and for very long periods of time. Given the present climate conditions and what is known about the current hydrologic system and conditions around and in the mountain itself, one would anticipate that the rates of infiltration, corrosion, and transport would be very low—except for the possibility that repository integrity might be compromised by low-probability disruptive events, which include earthquakes, strong ground motion, and (or) a repository-piercing volcanic intrusion/eruption. Extreme ground motions (ExGM), as we use the phrase in this report, refer to the extremely large amplitudes of earthquake ground motion that arise at extremely low probabilities of exceedance (hazard). They first came to our attention when the 1998 probabilistic seismic hazard analysis for Yucca Mountain was extended to a hazard level of 10-8/yr (a 10-4/yr probability for a 104-year repository “lifetime”). The primary purpose of this report is to summarize the principal results of the ExGM research program

  6. Abrupt climatic events recorded by the Ili loess during the last glaciation in Central Asia: Evidence from grain-size and minerals

    Science.gov (United States)

    Song, Yougui; Zeng, Mengxiu; Chen, Xiuling; Li, Yue; Chang, Hong; An, Zhisheng; Guo, Xiaohua

    2018-04-01

    The loess record of Central Asia provides an important archive of regional climate and environmental changes. In contrast to the widely investigated loess deposits in the Chinese Loess Plateau, Central Asian loess-paleosol sequences remain poorly understood. Here, we present an aeolian loess section in the southern Ili Basin. Based on granularity and mineralogical analyses, we reconstruct climatic changes during the last glaciation. The results indicated that most of the abrupt climatic events (such as Dansgaard-Oeschger events and Heinrich events) were imprinted in this loess section, although their amplitudes and ages showed some differences. Compared with the millennial oscillations recoded in loess and stalagmites in East Asia, the arid Central Asia responded more sensitively to the warming events than to the cooling events. The shifting trajectory of westerlies across Central Asia played an important role in dust deposition during the stadials. The North Atlantic climatic signals may have been transmitted from Central Asia to the East Asian monsoon regions via the westerlies.

  7. High-resolution sub-bottom seismic and sediment core records from the Chukchi Abyssal Plain reveal Quaternary glaciation impacts on the western Arctic Ocean

    Science.gov (United States)

    Joe, Y. J.; Seokhoon, Y.; Nam, S. I.; Polyak, L.; Niessen, F.

    2017-12-01

    For regional context of the Quaternary history of Arctic marine glaciations, such as glacial events in northern North America and on the Siberian and Chukchi margins, we used CHIRP sub-bottom profiles (SBP) along with sediment cores, including a 14-m long piston core ARA06-04JPC taken from the Chukchi abyssal plain during the RV Araon expedition in 2015. Based on core correlation with earlier developed Arctic Ocean stratigraphies using distribution of various sedimentary proxies, core 04JPC is estimated to extend to at least Marine Isotope Stage 13 (>0.5 Ma). The stratigraphy developed for SBP lines from the Chukchi abyssal plain to surrounding slopes can be divided into four major seismostratigraphic units (SSU 1-4). SBP records from the abyssal plain show well preserved stratification, whereas on the surrounding slopes thi