Sample records for carboniferous mountain glaciation

  1. Carboniferous Fusulinids from the Cantabrian Mountains (Spain)

    NARCIS (Netherlands)

    Ginkel, van A.C.


    Fusulinid faunas from various locations spread throughout the Cantabrian mountains are described as belonging to about 180 species including 17 new species and 11 new subspecies of 18 genera. The latter are Staffella (with 3 new species), Parastaffella (with 3 new species and 2 new subspecies), Mill

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

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


    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. Late Pleistocene glaciation of the Changbai Mountains in northeastern China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; NIU YunBo; YAN Ling; CUI ZhiJiu; LI ChuanChuan; MU KeHua


    The Changbai Mountains (2749 m a.s.l.) in northeastern China are one of the typical mountain regions with glaciation since late Pleistocene as evidenced by well-preserved erosive and accumulative land-forms at elevations above 2000 m a.s.l. Formed by glaciers around the crater lake, Tianchi Lake. Cirque glaciers developed on both the inner and outer sides of the volcanic cone. Well-preserved cirques, glacial trough valleys, glacial threholds, polished surfaces of the glacial erratics and the moraine ridges indicate that several glaciation processes took place during the last glacial period in this region. Re-sults of optically stimulated luminescence (OSL) dating on the moraine sediments, and the K/Ar, ther-mal ionization mass spectrometry (TIMS), electronic spinning resonance (ESR) dating on the volcanic rocks suggest two periods of glacier advances. One is named the Black Wind Mouth glacier advance taking place on the west and north slopes of the volcanic cone at an elevation of 2000-2100 m a.s.l.,which is dated to about 20 ka, being the result of the Last Glacial Maximum (LGM). The other is named the Meteorological Station glacier advance at the elevation of 2400--2600 m a.s.l., dated to 11 ka during the late glacial period, and is tentatively correlated to the Younger Dryas stage. The scope of the former glacier advance is larger than that of the latter. Regional comparisons showed that the glacial se-quences in the Changbai Mountains are similar to other glaciated areas in eastern Asia during the later part of the last glacial cycle.

  4. Lower Carboniferous marine bivalves from the Cantabrian Mountains (Spain)

    NARCIS (Netherlands)

    Amler, M.R.W.; Winkler Prins, C.F.


    The Lower Carboniferous bivalves of the Vegamián and Genicera formations are described, followed by a brief discussion on palaeoenvironmental and palaeogeographical aspects. The black shales of the Vegamián Fm. (Tournaisian) yield a peculiar association of euchondriid taxa (Euchondria wagneri sp. no

  5. Reconstructing the pre-Quaternary landscape in Agnew-Lawlers area, Western Australia with emphasis on the Permo-Carboniferous glaciation and post-glacial weathering (United States)

    Salama, Walid; Anand, Ravi R.


    redox reactions. The formation of smectite and ferruginous cements in this unit is attributed to weathering of ferromagnesian and opaque heavy minerals under oxic and slightly alkaline conditions. Mineralogical and geochemical changes dominated in the upper unit is related mainly to Post-Permian chemical weathering, where almost all rock-forming minerals are altered to kaolinite and alkali and alkaline earth elements are leached forming bleached white saprolitic diamictites. A change in clay minerals from kaolinite in the weathered Permo-Carboniferous succession to smectite in the overlying Cenozoic succession demarcates the unconformity and probably reflects a change to an arid climatic condition. Chemically, the Cenozoic succession shows a sharp increase in Ti/Al and La/Ce ratios and a decrease in Ce anomaly that remain constant in the Permo-Carboniferous section. These mineralogical and chemical variations through the Phanerozoic stratigraphic section can be used to follow the landscape and climatic evolution since the late Palaeozoic glaciation.

  6. Mountain uplift and the threshold for sustained Northern Hemisphere Glaciation

    Directory of Open Access Journals (Sweden)

    G. L. Foster


    Full Text Available The Miocene (~24 to ~5 million years ago was a period of relative global warmth (e.g. Zachos et al. 2001 characterised by the glaciation of Antarctica only. Paradoxically, the majority of available proxy data suggest that during the Miocene pCO2 was similar, or even lower, than the pre-industrial levels (280 ppmv; Pagani et al., 1999; Pearson and Palmer, 2000; Kürschner et al., 1996, 2008 and at times probably crossed the modelled threshold value required for sustained glaciation in the Northern Hemisphere (DeConto et al., 2008. Records of ice rafted debris and the oxygen isotope composition of benthic foraminifera suggest that at several times over the last 25 million years substantial amounts of continental ice did build up in the Northern Hemisphere but none of these led to sustained glaciation. In this contribution we review evidence that suggests that in the Miocene the North American Cordillera was, at least in parts, considerably lower than today. We present new GCM simulations that imply that Late Miocene uplift of the North American Cordillera would have resulted in significant cooling of Northern North American Continent. Offline ice sheet modelling, driven by these GCM outputs, suggests that with a reduced topography inception of the Cordilleran ice sheet is prohibited, and there is a small, but potentially significant, reduction in the amount of ice grown on Baffin Island. This suggests uplift of the North American Cordillera in the Late Miocene may have played an important role in priming the climate for the intensification of Northern Hemisphere glaciation in the Late Pliocene.

  7. History of research on glaciation in the White Mountains, New Hampshire (U.S.A.) (United States)

    Thompson, W.B.


    The glacial geology of the White Mountains in New Hampshire has been the subject of many investigations since the 1840's. A series of controversies evolved during this period. First was the question of what geologic processes were responsible for eroding the bedrock and depositing the cover of surficial sediments. By the 1860's, the concept of glaciation replaced earlier theories invoking floods and icebergs. Research in the late 1800's concerned the relative impact of continental versus local glaciation. Some workers believed that surficial deposits in northern New Hampshire were the product of valley glaciers radiating from the White Mountains, but in the early 1900's continental glaciation was established as the most important process across the region. Debate over the extent and timing of alpine glaciation in the Presidential Range has continued until recent years. The most intensely argued topic has been the manner in which the Late Wisconsinan ice sheet withdrew from the White Mountains: whether by rapid stagnation and downwastage, or by progressive retreat of a still-active ice margin. The stagnation model became popular in the 1930's and was unchallenged until the late 1900's. Following a research hiatus lasting over 40 years, renewed interest in the glacial history of the White Mountains continues to inspire additional work.

  8. Asynchronous glaciation at Nanga Parbat, northwestern Himalaya Mountains, Pakistan (United States)

    Phillips, William M.; Sloan, Valerie F.; Shroder, John F., Jr.; Sharma, Pankaj; Clarke, Michèle L.; Rendell, Helen M.


    We present a new glacial chronology demonstrating asynchroneity between advances of Himalayan glaciers and Northern Hemisphere ice-sheet volumes. Glaciers at Nanga Parbat expanded during the early to middle Holocene ca. 9.0 5.5 ka. No major advances at Nanga Parbat during the last global glacial stage of marine oxygen isotope stage 2 (MIS-2) between 24 and 11 ka were identified. Preliminary evidence also indicates advances between ca. 60 and 30 ka. These periods of high ice volume coincide with warm, wet regional climates dominated by a strong southwest Asian summer monsoon. The general lack of deposits dating from MIS-2 suggests that Nanga Parbat was too arid to support expanded ice during this period of low monsoon intensity. Advances during warm, wet periods are possible for the high-altitude summer accumulation glaciers typical of the Himalayas, and explain asynchronous behavior. However, the Holocene advances at Nanga Parbat appear to have been forced by an abrupt drop in temperature ca. 8.4 8.0 ka and an increase in winter precipitation ca. 7 5.5 ka. These results highlight the overall sensitivity of Himalayan glaciation to orbital forcing of monsoon intensity, and on millennial or shorter time scales, to changes in North Atlantic circulation.

  9. Multi-scale curvature for automated identification of glaciated mountain landscapes. (United States)

    Prasicek, Günther; Otto, Jan-Christoph; Montgomery, David R; Schrott, Lothar


    Erosion by glacial and fluvial processes shapes mountain landscapes in a long-recognized and characteristic way. Upland valleys incised by fluvial processes typically have a V-shaped cross-section with uniform and moderately steep slopes, whereas glacial valleys tend to have a U-shaped profile with a changing slope gradient. We present a novel regional approach to automatically differentiate between fluvial and glacial mountain landscapes based on the relation of multi-scale curvature and drainage area. Sample catchments are delineated and multiple moving window sizes are used to calculate per-cell curvature over a variety of scales ranging from the vicinity of the flow path at the valley bottom to catchment sections fully including valley sides. Single-scale curvature can take similar values for glaciated and non-glaciated catchments but a comparison of multi-scale curvature leads to different results according to the typical cross-sectional shapes. To adapt these differences for automated classification of mountain landscapes into areas with V- and U-shaped valleys, curvature values are correlated with drainage area and a new and simple morphometric parameter, the Difference of Minimum Curvature (DMC), is developed. At three study sites in the western United States the DMC thresholds determined from catchment analysis are used to automatically identify 5 × 5 km quadrats of glaciated and non-glaciated landscapes and the distinctions are validated by field-based geological and geomorphological maps. Our results demonstrate that DMC is a good predictor of glacial imprint, allowing automated delineation of glacially and fluvially incised mountain landscapes.

  10. Glacial advances and ESR chronology of the Pochengzi Glaciation,Tianshan Mountains,China

    Institute of Scientific and Technical Information of China (English)


    The Pochengzi Glaciation is a typical glaciation in Quaternary in the Tianshan Mountains. The glacial landforms comprise several integrated end moraines, like a fan spreading from the north to the south at the mouth of the Muzhaerte River valley and on the piedmont on the southeastern slope of the Tumur Peak, the largest center of modern glaciation in the Tianshan Mountains. The landforms recorded a complex history of the ancient glacier change and contained considerable information of the glacial landscape evolution, and dating these landforms helps us understand the temporal and spatial shifts of the past cryosphere in this valley and reconstruct the paleoenvironment in this region. Electron spin resonance (ESR) dating of the glacial tills in the upper stratum from a well-exposed section, end moraines, and associated outwashes was carried out using Ge centers in quartz grains, which are sensitive to the sunlight and grinding. The results could be divided into three clusters, 13.6–25.3, 39.5–40.4 and 64.2–71.7 ka. Based on the principle of geomorphology and stratigraphy and the available paleoen- vironmental data from northwestern China, the end moraines were determined to deposit in the Last Glaciation. The landforms and the three clusters of ages demonstrate that at least three large glacial advances occurred during the Pochengzi Glaciation, which are corresponding to marine oxygen isotope stage 4 (MIS4), MIS3b and MIS2. The landforms also indicate that the gla- ciers were compound valley glacier in MIS2 and MIS3b and piedmont glacier in MIS4, and the ancient Muzhaerte glacier were 94, 95 and 99 km at their maximum extensions in these three glacial advances.

  11. Geomorphological and sedimentary evidence of probable glaciation in the Jizerské hory Mountains, Central Europe (United States)

    Engel, Zbyněk; Křížek, Marek; Kasprzak, Marek; Traczyk, Andrzej; Hložek, Martin; Krbcová, Klára


    The Jizerské hory Mountains in the Czech Republic have traditionally been considered to be a highland that lay beyond the limits of Quaternary glaciations. Recent work on cirque-like valley heads in the central part of the range has shown that niche glaciers could form during the Quaternary. Here we report geomorphological and sedimentary evidence for a small glacier in the Pytlácká jáma Hollow that represents one of the most-enclosed valley heads within the range. Shape and size characteristics of this landform indicate that the hollow is a glacial cirque at a degraded stage of development. Boulder accumulations at the downslope side of the hollow probably represent a relic of terminal moraines, and the grain size distribution of clasts together with micromorphology of quartz grains from the hollow indicate the glacial environment of a small glacier. This glacier represents the lowermost located such system in central Europe and provides evidence for the presence of niche or small cirque glaciers probably during pre-Weichselian glacial periods. The glaciation limit (1000 m asl) and paleo-ELA (900 m asl) proposed for the Jizerské hory Mountains implies that central European ranges lower than 1100 m asl were probably glaciated during the Quaternary.

  12. Progressive impact of glaciation on mountain erosion and topography: insights from in-situ thermochronometry (United States)

    Valla, Pierre


    Glacial processes have shaped conspicuous landscapes at the Earth surface. In alpine environments, glacial pre-conditioning of the topography exerts a strong control on the geomorphological response following glacier retreat. However, whether the late Cenozoic climate cooling and onset of glaciation have had a widespread impact on mountain erosion remains debated. Sediment budgets, in various mountain ranges and at a global scale, show an increase in sediment fluxes during the late Neogene, although their interpretation as proxy for increased erosion is challenged. In-situ low-temperature thermochronometry (including recent developments such as 4He/3He and OSL thermochronometry) records rock exhumation within the upper crust to quantify long-term erosion and relief histories. Here I will review some recent thermochronometric studies that investigate the mountain erosional and topographic response to glaciation, going from mid- to high-latitude regions. In the European Alps, recent apatite 4He/3He data combined with thermal-kinematic modelling suggest a significant increase in topographic relief over the last ˜1 Myr, with 1-1.5 km of valley deepening by large and erosive glaciers. This episode is synchronous with the Mid-Pleistocene climatic transition from symmetric 40-kyr to strongly asymmetric 100-kyr glacial/interglacial cycles. Similar findings in other mountain ranges, as well as recent compilations at a global scale, point toward a globally averaged (but more pronounced at mid-latitudes) increase in erosion rates since 1-2 Ma. This would support the assumption that enhanced climatic variability during the Plio-Pleistocene, rather than cooling through the Late Cenozoic, has controlled mountain erosion and topography. However, in the high-latitude settings of the Patagonian Andes and southern Alaska, which have been glaciated since the late Miocene, new thermochronometric results show that a substantial increase in erosion had already occurred at ˜6-8 Ma

  13. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes. (United States)

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


    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 hydrologic-altering 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.

  14. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes (United States)

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


    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.

  15. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes (United States)

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


    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 hydrologic-altering 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. PMID:27386570

  16. Environmental evolution in the Picos de Europa (Cantabrian Mountains, SW Europe) since the Last Glaciation (United States)

    Ruiz-Fernández, Jesús; Oliva, Marc; Cruces, Anabela; Lopes, Vera; Freitas, Maria da Conceição; Andrade, César; García-Hernández, Cristina; López-Sáez, José Antonio; Geraldes, Miguel


    The Western Massif of the Picos de Europa (latitude 43° N, longitude 4-5° W) includes some of the highest peaks in the Cantabrian Mountains. This massif was heavily glaciated during the Last Glaciation, though the post-glacial environmental evolution is still poorly understood. Using a complementary geomorphological and sedimentological approach, we have reconstructed the environmental events occurred in this massif since the last Pleistocene glaciation. The geomorphological distribution of glacial landforms suggests the occurrence of four main glacial stages: maximum glacial advance, glacial expansion after the maximum advance, Late Glacial and Little Ice Age. Moreover, a 5.4-m long sedimentary sequence was retrieved from the karstic depression of Belbín providing a continuous record of the paleoenvironmental conditions in this area since the Last Glaciation until nowadays. This section suggests that the maximum glacial expansion occurred at a minimum age of 37.2 ka cal BP, significantly prior to the global Last Glacial Maximum. Subsequently, periglacial processes prevailed in the mid lands of the massif until glaciers expanded between 22.5 and 18.7 ka cal BP. Following the melting of the glaciers, a shallow lake appeared in the Belbín depression. Lake sediments do not show evidence of a cold stage during the Late Glacial, when moraine systems formed at higher locations. The terrestrification of this lake started at 8 ka cal BP and the area turned into grassland. At 4.9 ka cal BP the existence of charcoal particles in the sediments of Belbín sequence reveals the onset of human occupation in the massif through the use of fire activity for grazing purposes. Finally, the presence of moraines inside the highest northern cirques shows evidence of the last glacial phase that occurred during the Little Ice Age cold event. Since then, the warming climate has led to the melting of these glaciers and periglacial processes prevail in the high lands of the massif.

  17. Climatic sensitivity of the non-glaciated mountains cryosphere (Tatra Mts., Poland and Slovakia) (United States)

    Gądek, Bogdan


    This paper concerns the response of the conditioned by orography cryosphere of the non-glaciated mountains of mid-latitude to the climate impulses. It presents the relationships among the air temperature, precipitation, snow cover, lake ice cover, firn-ice patches (glacierets) and permafrost in the Tatras. The data from the warmest multi-year in the history of the local meteorological measurements and statistical models (multiple regression) have been used. The results indicate that all the components of the contemporary cryosphere are very sensitive to the changes in the air temperature in winter or snow precipitation/accumulation. Due to the diverse orographic conditions, interannual variability of seasonal and perennial, surface and subsurface ice deposits in the mountain areas may not be synchronous. However, the long-term trends of this variability reflect the changes in the global climate system.

  18. Insights into the evolution of tectonically-active glaciated mountain ranges from digital elevation model analyses (United States)

    Brocklehurst, S. H.; Whipple, K. X.


    Glaciers have played an important role in the development of most active mountain ranges around the world during the Quaternary, but the interaction between glacial erosion (as modulated by climate change) and tectonic processes is poorly understood. The so-called glacial buzzsaw hypothesis (Brozovic et al., 1997) proposes that glaciers can incise as rapidly as the most rapid rock uplift rates, such that glaciated landscapes experiencing different rock uplift rates but the same snowline elevation will look essentially the same, with mean elevations close to the snowline. Digital elevation model-based analyses of the glaciated landscapes of the Nanga Parbat region, Pakistan, and the Southern Alps, New Zealand, lend some support to this hypothesis, but also reveal considerably more variety to the landscapes of glaciated, tectonically-active mountain ranges. Larger glaciers in the Nanga Parbat region maintain a low downvalley gradient and valley floor elevations close to the snowline, even in the face of extremely rapid rock uplift. However, smaller glaciers steepen in response to rapid uplift, similar to the response of rivers. A strong correlation between the height of hillslopes rising from the cirque floors and rock uplift rates implies that erosion processes on hillslopes cannot initially keep up with more rapid glacial incision rates. It is these staggering hillslopes that permit mountain peaks to rise above 8000m. The glacial buzzsaw hypothesis does not describe the evolution of the Southern Alps as well, because here mean elevations rise in areas of more rapid rock uplift. The buzzsaw hypothesis may work well in the Nanga Parbat region because the zone of rapid rock uplift is structurally confined to a narrow region. Alternatively, the Southern Alps may not have been rising sufficiently rapidly or sufficiently long for the glacial buzzsaw to be imposed outside the most rapidly uplifting region, around Mount Cook. The challenge now is to understand in detail

  19. Enhanced oxidative weathering in glaciated mountain catchments: A stabilising feedback on atmospheric carbon dioxide? (United States)

    Horan, K.; Hilton, R. G.; Burton, K. W.; Selby, D. S.; Ottley, C. J.


    Mountain belts act as sources of carbon dioxide (CO2) to the atmosphere if physical erosion and exhumation expose rock-derived organic carbon ('petrogenic' organic carbon, OCpetro) to chemical weathering. Estimates suggest 15x1021g of carbon is stored in rocks globally as OCpetro, ~25,000 times the amount of carbon in the pre-industrial atmosphere. Alongside volcanic and metamorphic degassing, OCpetro weathering is thought to be the main source of CO2 to the atmosphere over geological timescales. Erosion in mountain river catchments has been shown to enhance oxidative weathering and CO2 release. However, we still lack studies which quantify this process. In addition, it is not clear how glaciation may impact OCpetro oxidation. In analogy with silicate weathering, large amounts of fine sediment in glacial catchments may enhance oxidative weathering. Here we quantify oxidative weathering in nine catchments draining OCpetro bearing rocks in the western Southern Alps, New Zealand. Using rhenium (Re) as a tracer of oxidative weathering, we develop techniques to precisely measure Re concentration at sub-ppt levels in river waters. Using [Re]water/[Re]rock as a weathering tracer, we estimate that the weathering efficiency in glacial catchments is >4 times that of non-glacial catchments. Combining this with the OCpetro content of rocks and dissolved Re flux, we estimate the CO2 release by OCpetro oxidation. The analysis suggests that non-glacial catchments in the western Southern Alps release similar amounts of CO2 as catchments in Taiwan where erosion rates are comparable. In this mountain belt, the CO2 release does not negate CO2 drawdown by silicate weathering and by riverine transfer of organic matter. Based on our results, we propose that mountain glaciation may greatly enhance OCpetro oxidation rates. Depending on the global fluxes involved, this provides a feedback to damp low atmospheric CO2 levels and global cooling. During glacial periods (low CO2, low global

  20. Late Pleistocene glaciation of the Hulifang Massif of Gongwang mountains in Yunnan Province%云南东北部拱王山末次冰期

    Institute of Scientific and Technical Information of China (English)

    张威; 崔之久; 冯金良


    Late Pleistocene glaciation was restricted to only a few high mountains in eastern China.The Gongwang mountains constitute one of the typical places once glaciated. Geomorphic mapping of the area and the TL dating provides evidence for at least four distinct glaciations. YJT-Ⅰ glacial advance occurred about 100 ka BP and two TL absolute ages (101,100 ± 7780 a BP; 104,000± 8300 a BP) indicate this advance happened during the Penultimale Glaciation. The early stage glacial advance (YJT-Ⅱ advance) during the last glaciation occurred about 40,920 ± 3400 a BP. The last glacial maximum advance (YJT-Ⅲ advance) about 18-25 ka BP, which sustained by two TL ages (18,230 ±1420 a BP; 25,420 ± 2110 a BP). The Penultimale and the early stage glaciations were more extensive and the last glacial maximum (LGM) and the late-glacial period (YJT-Ⅳ advance, 10 ka BP) were progressively less extensive. Correlated with the other mountains in eastern China, these glacial advances in the Gongwang mountains just like the advances in the western part such as Diancang mountains, Yulong mountains of Yunnan Province and the glacier series are more complete than the adjacent mid-latitude regions such as Taibai mountain and Taiwan mountains and are roughly representative of climate changes during the last glacial cycle in Yunnan Province.

  1. Carboniferous Productidina and Chonetidina of the Cantabrian Mountains (NW Spain): Systematics, stratigraphy and palaeoecology

    NARCIS (Netherlands)

    Winkler Prins, C.F.


    The Carboniferous sediments of the thrust structures between the Porma and Bernesga rivers (map 2) and the headwaters of a tribuary of the Luna River (map 3) are described. In the lithostratigraphic chapter, the Vegamián, Alba, Escapa and San Emiliano formations are described, ranging in age from th

  2. The Significance of High, Isolated, Low-relief Surfaces in Glaciated Mountain Ranges (United States)

    Brocklehurst, S. H.


    The highest regions of glaciated mountain ranges are characterised by cirques, arêtes and steep hillslopes. In addition, though, many ranges exhibit high, isolated, low-relief surfaces, which may provide an important record of landscape evolution. Broad, low-curvature surfaces, for example in the Laramide Ranges of the western United States, reflect periglacial regolith production and transport (e.g., Anderson, 2002). Here, the focus is on smaller surfaces that appear to be out of equilibrium with current/recent surface processes, and are interpreted as former glacial valley floors isolated from the current valley network. The low-relief surfaces at the crest of the Sierra Nevada, California, are diamict covered. The top of Sardine Canyon is a beheaded cirque, while the cirque on the western side of Baxter Pass is in the process of being beheaded. Meanwhile, the isolated patch of diamict on the northeastern ridge of University Peak is surrounded on all sides by steep cliffs, and presumably represents a more evolved surface. It is inferred that the glaciated eastern Sierra Nevada is subject to a cycle of drainage capture and relief inversion, driven by headward erosion by cirque glaciers. The central Himalaya contains a number of low-relief, ice-covered surfaces far above the rest of the glacial valley network (e.g., the Sakyetang Glacier, >6,600m, above the Kazhen Glacier, 6,000m is frozen to the bedrock, so sub-glacial erosion will be outpaced by rock uplift. The extreme relief and active tectonics of the central Himalaya mean that drainage capture is not necessarily required in the generation of high, isolated, low-relief surfaces; glacial steps can become exaggerated to form reconstituted glaciers. High, isolated, low-relief surfaces are found across the Southern Alps, New Zealand, from Miserable Ridge and Kelly Saddle close to the western range front, through Urquhart Peak and Lake Browning near the Main Divide, to Kaimakamaka Peaks east of the Main Divide. As

  3. Lithostratigraphy, microlithofacies, and conodont biostratigraphy and biofacies of the Wahoo Limestone (Carboniferous), eastern Sadlerochit Mountains, Northeast Brooks Range, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Krumhardt, A.P.; Harris, A.G.; Watts, K.F. [Univ. of Alaska, Fairbanks, AK (United States)


    The Lisburne Group (chiefly Carboniferous) is a wide-spread succession of platform carbonate rocks that apparently developed along a south-facing passive continental margin in northern Alaska. Marine transgressions onlapped northward across northeast Alaska allowing the Lisburne platform to extend over terrigenous deposits of the Endicott Group and local pre-Mississippian paleotopographic highs. The Wahoo Limestone is the youngest formation of the Lisburne Group in northeasternmost Alaska, ranging from latest Mississippian (latest Chesterian) to Middle Pennsylvanian (at least early Atokan) in age. The Wahoo Limestone was systematically sampled for lithostratigraphy and conodont biostratigraphy and biofacies at a relatively continuous section (about 262 m in thickness) in the eastern Sadlerochit Mountains. Existing Carboniferous conodont zonations could not be readily applied to the study section because most zonal indicators are absent. Species diversity is low for a section that spans at least 10 million years. Twenty-four species, distributed among 14 genera, were identified in 72 productive samples; no new species were distinguished. The following biostratigraphic zones and faunal intervals were recognized: Upper muricatus Subzone (latest Chesterian); noduliferus-primus Zone (earliest Morrowan); minutus Fauna (Morrowan) containing a lower subdivision (lower minutus Fauna of early to middle? Morrowan age); and an Idiognathodus Fauna (Morrowan? to early Atokan). The presence of Idiognathodus incurvus? and Rhachistognathus minutus subspp. above the first occurrence of the foraminifer Pseudostaffella sp. in the uppermost part of the Wahoo Limestone indicates that the youngest beds are early Atokan in age. The Mississippian-Pennsylvanian boundary is placed at 56 m above the base of the lower member of the Wahoo Limestone on the basis of the lowest occurrence of Declinognathodus noduliferus japonicus above forms transitional from Gnathodus girtyl simplex.

  4. High-alumina basalts from the Bogda Mountains suggest an arc setting for Chinese Northern Tianshan during the Late Carboniferous (United States)

    Xie, Wei; Xu, Yi-Gang; Chen, Yi-Bing; Luo, Zhen-Yu; Hong, Lu-Bing; Ma, Liang; Liu, Hai-Quan


    Considerable debate persists as to the tectonic setting of the Tianshan Orogen during the Late Paleozoic, with active subduction system and intraplate large igneous provinces as two dominant schools. With aims of providing constraints on this issue, geochronological and geochemical analyses have been carried out on the Late Carboniferous high-Al basaltic lava (HAB) from the Bogda Mountains. These lavas, in conformable contact with the felsic rocks, belong to the Upper Carboniferous Liushugou Group. Zircon SHRIMP U-Pb dating of two felsic ignimbrites further suggest that they were mainly erupted during 315-319 Ma. The Bogda basaltic lava is classified as HAB given their high Al contents > 16% and their chemical resemblance to those from modern arcs such as Aleutian and Kamchatka. They are characterized by strong enrichment in large ion lithophile elements (LILE), strong negative Nb-Ta and Ti anomalies, and distinct positive Pb anomalies. Hence, they are significantly different from the mantle plume-related basalts, as exemplified by those from Siberian, Emeishan, and Tarim large igneous provinces. Instead, their MORB-like Nd-Hf-Pb isotopes and arc-like trace elements indicate that the Bogda HABs may have been generated from a mantle wedge metasomatized by sediment-derived melts. The sector and oscillatory zoning in clinopyroxene phenocrysts in the Bogda HABs is attributable to rapid dynamic crystallization during magma ascent. High Al content is due to delayed plagioclase nucleation likely by the high crystallization pressure rather than water content. Collectively, our data lend support to an island arc environment during the Late Paleozoic, probably related to southward subduction of the Paleo-Tianshan Ocean.

  5. The impact of the Quaternary glaciations on the Durmitor mountains (Montenegro) as understood from detailed geomorphological mapping (United States)

    Frankl, Amaury; Annys, Klaas; Spalević, Velibor; Čurović, Milic; Borota, Dragan; Nyssen, Jan


    In the Balkans, few studies exist that highlight the impact of the Quaternary glaciations on the landscape. However, the impact of the Quaternary glaciations was important and the glacial imprint remains well preserved in the limestone massifs where karst hydrology prevails. This study presents a detailed geomorphological map at scale 1:10,000 that was prepared of the northeastern Durmitor mountains (2523 m a.s.l.) and the plateau Jezerska Površ (47 km², Dinaric Alps, Montenegro). Mapping occurred from an intensive fieldwork campaign and remote sensing analysis, and was finalized in a GIS environment. The basic components of the legend are (i) processes/genesis, (ii) materials, (iii) morphometry/morphography, (iv) hydrography, (v) vegetation and (vi) anthropogenic features, that are organized as a box-of-bricks type of legend (AGRG-system). The geomorphological setting of the area consists of Mesozoic limestones which were eroded physically by Quaternary glacial and periglacial activity and chemically during interglacials. Glacial deposits of three Middle to Late Pleistocene glacial phases exist on the plateau, only scarcely dissected by meltwater channels. In the mountains, Holocene glacier retreat left behind a series of well-preserved recessional moraines and a static glacier remains in the cirque head. The presented map serves as a valuable tool for Quaternary research in the Durmitor Mountains, and serves as an example on the interaction between glacial and karst processes. Keywords: Debeli Namet glacier, Dinaric Alps, Geographic Information System (GIS), Glacial landforms, Karst.

  6. Late Pleistocene glaciation of the Kodar Mountains, south-central Siberia, constrained by Be-10 exposure dating (United States)

    Margold, Martin; Jansen, John D.; Gurinov, Artem L.; Reznichenko, Natalya V.; Codilean, Alexandru T.; Fink, David


    The glacial history of the mountainous Transbaikalia region NE of Lake Baikal, Siberia, has so far received little attention. The Kodar Mountains exceed 3000 m in elevation and small cirque glaciers currently occur in the central parts of the range. Yet, greatly expanded glaciation in the past is evidenced by massive moraine complexes at the mouth of glacial valleys in the Chara Depression (part of the Baikal rift system), and along the Vitim River valley to the NW. The moraines document the existence of large valley glaciers that reached to over 120 kilometres in length. We applied Be-10 exposure dating to determine the timing of glacier advances that formed the major moraines: 19 samples from boulders on 8 moraine ridges in 5 moraine complexes. Our results indicate extensive glaciation in the Kodar Mountains at the time of the Last Glacial Maximum, with our ages spanning from about 20 ka to the Late Glacial. We attribute the age spread on some of the moraines to boulder exhumation linked to permafrost dynamics.

  7. Internal structure and depositional environment of Late Carboniferous mounds from the San Emiliano Formation, Cármenes Syncline, Cantabrian Mountains, Northern Spain



    Well-exposed mounds are common in limestone of the Late Carboniferous San Emiliano Formation, Cantabrian Mountains (Northern Spain). They occur as obvious primary topographic features. Careful study of the mound intervals and surrounding strata revealed the internal structures of mounds and the factors controlling their growth. The substrate (2–3 m) of the mounds consists of greyish to reddish, bedded oolitic and oncolithic packstone and grainstone. Crinoids, fragments of the alga Epimastopor...

  8. Phylogeography of the large white-bellied rat Niviventer excelsior suggests the influence of Pleistocene glaciations in the Hengduan mountains. (United States)

    Chen, Weicai; Liu, Shaoying; Liu, Yang; Hao, Haibang; Zeng, Bo; Chen, Shunde; Peng, Hongyuan; Yue, Bisong; Zhang, Xiuyue


    The Hengduan Mountains, situated in the southeastern Tibetan Plateau, have undergone dramatic geological and climatic changes over the Pleistocene epoch. Several studies have revealed that the mountains served as a refugium during the ice age. The large white-bellied rat Niviventer excelsior is a rodent endemic to the Hengduan Mountains, which makes it an appropriate species for investigating the influence of glacial movements on the genetic structure of mammals. In this study, we sequenced the partial mitochondrial DNA control region from 72 N. excelsior specimens collected from 20 localities. The results revealed very high levels of haplotype diversity (h = 0.947) and nucleotide diversity (pi = 0.101) in this species. No common haplotype was found to be shared in samples from all geographic regions. Demographic analyses suggested that N. excelsior populations had not been subject to either expansion or bottleneck. The phylogenetic relationships among the haplotypes have no correlation with their geographical origins, while topology revealed two major clades. We speculate that the populations of N. excelsior may have been restricted to two separate refugia during the Last Glacial Maximum (0.60-0.17 Mya), with one west and one east of the Shaluli Mountains. Between the two major refugia, there existed a more widely distributed network subrefugia, which conserved genetic variations in N. excelsior. These results indicated that complex topographic configuration in the Hengduan Mountains provided a network of refugia to maintain the high level of genetic diversity in Pleistocene glaciations.

  9. A juvenile Early Carboniferous (Viséan coelacanth from Rösenbeck (Rhenish Mountains, Germany with derived postcranial characters

    Directory of Open Access Journals (Sweden)

    F. Witzmann


    Full Text Available A small coelacanth specimen of Viséan age from a newly described locality near Rösenbeck at the northern margin of the Rhenish Mountains (North Rhine-Westphalia, Germany is described. The head and pectoral girdle are not preserved, however, the specimen can be distinguished from all other known Carboniferous coelacanths by derived characters of the articulated postcranial skeleton. Derived characters include: (1 The slender first and second dorsal fins that carry only seven to eight and six fin rays, respectively. (2 Both the pelvic and anal fin have a broad base and are unusually weakly lobed. (3 The fin rays of the second dorsal fin are much more robust than those of the first dorsal fin. (4 The second dorsal and anal fins are longer than the first dorsal and pelvic fins. The Rösenbeck coelacanth is interpreted as a juvenile specimen, since the basal plates that support the fins are not ossified. doi:10.1002/mmng.201000004

  10. 10Be exposure age chronology of the last glaciation in the Krkonoše Mountains, Central Europe (United States)

    Engel, Zbyněk; Braucher, Régis; Traczyk, Andrzej; Laetitia, Léanni; AsterTeam


    A new chronology of the last glaciation is established for the Krkonoše (Giant) Mountains, Central Europe, based on in-situ produced 10Be in moraine boulders. Exposure ages and Schmidt Hammer rebound values obtained for terminal moraines on the northern and southern flank of the mountains suggest that the oldest preserved moraines represent early phases of the Last Glacial Maximum (LGM). Large moraines at the outlet of the Snowy Cirques (Śnieżne Kotły) and in the middle part of the Úpa (Obří důl) trough were deposited around 21 ka while a series of smaller moraines above the LGM deposits represent readvances that occurred no later than 18.1 ± 0.6 ka, 15.7 ± 0.5 ka, 13.5 ± 0.5 ka and 12.9 ± 0.7 ka. An exposure age of 13.8 ± 0.4 ka obtained for protalus ramparts at the foot of the Úpská jáma Cirque headwall indicates that glaciers advanced only in north- to east-facing cirques during the Lateglacial. The last glacier fluctuation was synchronous with the Younger Dryas cold event. The timing of local glacier advances during the last glacial episode correlates with the late Weichselian glacier phases in the Alps and in the Bavarian/Bohemian Forest.

  11. The Pleistocene Glaciation in the Karakoram-Mountains:Reconstruction of Past Glacier Extensions and Ice Thicknesses

    Institute of Scientific and Technical Information of China (English)

    Matthias Kuhle


    Geomorphological and Quaternarygeological field- and laboratory data (Fig.1) are introduced and interpreted with regard to the maximum Ice Age (LGM) glaciation of the Centraland South Karakoram in the Braldu-, Basna-, Shigarand Indus valley system as well as on the Deosai plateau between the Skardu Basin and the Astor valley (Fig.2). These data result from two research expeditions in the years 1997 and 2000. They show that between c. 60 and 20 Ka the Central Karakorum and its south slope were covered by a continuous c.125,000 km2 sized ice stream network. This ice stream network flowed together to a joint parent glacier, the Indus glacier. The tongue end of the Indus glacier reached down to 850 ~ 800 m a.s.l. In its centre the surface of this Indus ice stream network reached a height of a good 6000 m. Its most important ice thicknesses amounted to c. 2400 ~2900 m.

  12. The drowning of a carbonate platform: an example from the Devonian-Carboniferous of the southwestern Holy Cross Mountains, Poland (United States)

    Szulczewski, M.; Belka, Z.; Skompski, S.


    The broad Middle Devonian carbonate platform of the Holy Cross Mountains was fragmented during the Frasnian and afterwards submerged as isolated blocks and transformed into a topographic depression. The section exposed in the Ostrowka quarry illustrates a well-documented drowning of the last small fragment (seamount) of this carbonate platform which submerged during Late Devonian and Early Carboniferous times. The recognized facies succession reflects a progressive, stepwise lowering of the sediment surface through time from a peritidal, lagoonal environment to a deep-water, anoxic basin. The Frasnian shallow-water carbonate platform is represented by lagoonal facies with peritidal sediments. Small-scale deepening-upward cycles punctuated with emersion surfaces are a feature of this stage. They resulted from a combination and continuous balance between carbonate production, subsidence and low-order, eustatic sea-level fluctuations. The carbonate platform aggraded at rates around 100-125 m/Ma. The shallow-water peritidal carbonates are separated from the post-platform deposits by an unconformity surface developed during subaerial exposure. The flooding of the faulted block of Galezice in the pre-late marginifera time and the subsequent initial drowning resulted primarily from a rapid sea-level rise. Small dimension of the seamount and its cemented upper surface were the most important factors that facilitated the sediment removal and thus suppressed the sediment accumulation. A condensed section was deposited on the top of the seamount. Its stratigraphic succession and rare cephalopod storm beds account for a model of redistribution of sediment over the swell, disintegrated by small-scale faulting. During drowning, the seamount traversed down through the photic zone at an average rate not higher than 20-25 m/Ma. Transformation of the swell into a basin accelerated in the late Tournaisian anchoralis Zone. It is manifested by an increase of deposition rate and by a

  13. Dynamics of mountain glaciation in the South-Eastern Siberia over the past 160 years

    Directory of Open Access Journals (Sweden)

    E. Y. Osipov


    Full Text Available Changes in areas of glaciers in three South-East Siberian mountainous regions (East Sayan, Baikalsky and Kodar ridges had been analyzed for the period since end of Little Ice Age (LIA to the present time (about 160 years. It was determined that since the end of LIA area of these glaciers reduced, on the aver- age, by 59% (or 0.37% per a year, and their termini retreated by 550 m (3.5 m/year. At the second half of 20th century deglaciation in mountains of South- Eastern Siberia proceeded more intensive than in other Siberian regions. 

  14. 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.


    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. Furth

  15. Extensive glaciations in Anatolian Mountains during the global Last Glacial Maximum (United States)

    Akçar, Naki; Yavuz, Vural; Ivy-Ochs, Susan; Yeşilyurt, Serdar; Reber, Regina; Tikhomirov, Dmitry; Kubik, Peter; Vockenhuber, Christof; Schlüchter, Christian


    As a response to the changes in the atmospheric circulation at the beginning of the Last Glacial Maximum (LGM), equilibrium line altitude commenced to decrease and, thus, also Anatolian glaciers started to expand. Depending on the altitude of the mountains and size of the accumulation area, the advance began earlier in the eastern Black Sea Mountains prior to 27 ka. In the Kavron, Verçenik, Başyayla and Çoruh valleys, glaciers terminated at an altitude of 1600 m with a length of > 10 km. In eastern Anatolia, 15 km-long glaciers descended to 1400 m from the extensive ice-fields of the Munzır Mountains. In central and western Anatolia, glaciers were smaller (ca. 6 km-long) except for Dedegöl Mountains. There, a glacier length of around 9 km and an advance down to 1450 m were mapped. At Mount Erciyes glaciers began to advance down to 2150 m prior to 25 ka. In southwestern Anatolia, beginning of the LGM advance was documented at ca. 22 ka at Mount Sandıras, where a 1.5 km-long cirque glacier terminated at an altitude of 1900 m. Meanwhile, valley glaciers descended to 2050 m at Mount Akdaǧ, 6 km down from the peak. In northwestern Anatolia, one paleoglacier commenced to grow prior to ca. 25 ka at Uludaǧ and it reached a length of 5 km and an altitude 1600 m. In brief, Anatolian glaciers reached their maximum extent between 27 and 21 ka during the global LGM. The LGM deglaciation resulted in the collapse of Anatolian glaciers. The deglaciation was almost synchronous in all mountains. Climatic fluctuations at the end of LGM have produced only small glaciers, which are much more sensitive to temperature and/or precipitation changes than larger glaciers. Our recent study at Uludaǧ revealed that the glaciers re-advanced at least three times until 19 ka after their maximum extent at around 21 ka. We explain this dynamic behaviour as a response mechanism to different phases of the winter indices of the North Atlantic Oscillation, which resulted in an enhanced

  16. Late Pleistocene glaciation and deglaciation in the Crestone Peaks area, Colorado Sangre de Cristo Mountains, USA - chronology and paleoclimate (United States)

    Leonard, Eric M.; Laabs, Benjamin J. C.; Plummer, Mitchell A.; Kroner, Ryan K.; Brugger, Keith A.; Spiess, Vivian M.; Refsnider, Kurt A.; Xia, Yidong; Caffee, Marc W.


    Cosmogenic 10Be surface-exposure dating and numerical glacier modeling are used to reconstruct glacial chronology and climate in the Colorado Sangre de Cristo Mountains during the local last glacial maximum (LLGM) and the subsequent deglaciation. Twenty-two surface-exposure ages on moraine boulders and polished-bedrock outcrops in the Willow Creek valley and ten in two adjacent valleys indicate that glaciers were at or near their maxima from ∼21 ka until 17-16 ka, and then retreated rapidly, nearly deglaciating the Willow Creek valley entirely by ∼14 ka. Coupled energy/mass-balance and flow modeling of two of the glaciers indicates that, if changing ice extent was driven only by temperature and insolation changes, temperature depressions of 5.0 and 5.1 °C from modern conditions, with an uncertainty of approximately + 1.5 / - 1.0 °C, would have sustained the glaciers in mass-balance equilibrium at their LLGM extents. Doubling or halving of modern precipitation during the LLGM would have been associated with 2.7-3.0 °C and 6.9-7.0 °C temperature depression respectively. Approximately half of the subsequent LLGM-to-modern climate change was accomplished by ∼14 ka. If the rapid main phase of deglaciation between about 16 ka and 14 ka was driven solely by temperature and insolation changes, it would have been associated with a temperature rise of about 2.5 °C, at a mean rate of approximately 1.1 °C/ky. This new chronology of the last glaciation is generally consistent with others developed recently in the Colorado Rocky Mountains. The numerical modeling, however, suggests a lesser LLGM temperature depression from modern conditions than have most previous studies in Colorado.

  17. Comparing the skill of different reanalyses and their ensembles as predictors for daily air temperature on a glaciated mountain (Peru) (United States)

    Hofer, Marlis; Marzeion, Ben; Mölg, Thomas


    It is well known from previous research that significant differences exist amongst reanalysis products from different institutions. Here, we compare the skill of NCEP-R (reanalyses by the National Centers for Environmental Prediction, NCEP), ERA-int (the European Centre of Medium-range Weather Forecasts Interim), JCDAS (the Japanese Meteorological Agency Climate Data Assimilation System reanalyses), MERRA (the Modern Era Retrospective-Analysis for Research and Applications by the National Aeronautics and Space Administration), CFSR (the Climate Forecast System Reanalysis by the NCEP), and ensembles thereof as predictors for daily air temperature on a high-altitude glaciated mountain site in Peru. We employ a skill estimation method especially suited for short-term, high-resolution time series. First, the predictors are preprocessed using simple linear regression models calibrated individually for each calendar month. Then, cross-validation under consideration of persistence in the time series is performed. This way, the skill of the reanalyses with focus on intra-seasonal and inter-annual variability is quantified. The most important findings are: (1) ERA-int, CFSR, and MERRA show considerably higher skill than NCEP-R and JCDAS; (2) differences in skill appear especially during dry and intermediate seasons in the Cordillera Blanca; (3) the optimum horizontal scales largely vary between the different reanalyses, and horizontal grid resolutions of the reanalyses are poor indicators of this optimum scale; and (4) using reanalysis ensembles efficiently improves the performance of individual reanalyses.

  18. In situ cosmogenic 10Be dating of the Quaternary glaciations in the southern Shaluli Mountain on the Southeastern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG; Jian; Raisbeck; Grand; XU; Xiaobin; Yiou; Francios; BAI; Shibiao


    It is generally considered that four-times ice age happened during the Quaternary epoch on the Tibetan Plateau.However,the research on the chronology of the four-times ice age is far from enough.The Shaluli Mountain on the Southeastern Tibetan Plateau is an ideal place for plaeo-glacier study,because there are abundant Quaternary glacial remains there.This paper discusses the ages of the Quaternary glaciations,based on the exposure dating of roche moutonnée,moraines and glacial erosion surfaces using in situ cosmogenic isotopes 10Be.It is found that the exposure age of the roche moutonnée at Tuershan is 15 ka,corresponding to Stage 2 of the deep-sea oxygen isotope,suggesting that the roche moutonnée at Tuershan is formed in the last glacial maximum.The exposure age of glacial erosion surface at Laolinkou is 130-160 ka,corresponding to Stage 6 of the deep-sea oxygen isotope.The oldest end moraine at Kuzhaori may form at 421-766 kaBP,corresponding to Stages 12-18 of the deep-sea oxygen isotope.In accordance with the climate characteristic of stages 12,14,16 and 18 reflected by the deep-sea oxygen isotope,polar ice cores and loess sequence,the oldest end moraine at Kuzhaori may form at stage 12 or stage 16,the latter is more possible.

  19. Cyclostratigraphy of Uppermost Carboniferous-to-Lower Triassic Terrestrial Deposits in Bogda Mountains, NW China - A Potential Astrostratigraphic Proxy Section (United States)

    Yang, W.; Tabor, N. J.; Crowley, J. L.; Miggins, D. P.; Obrist, J.


    Lithologic and stratigraphic evidence from the uppermost Carboniferous-Lower Triassic fluvial-lacustrine deposits in the Tarlong-Taodonggou half-graben of southern Bogda Mountains, NW China shows 3 orders of depositional cyclicity. The section is thick (~1,700 m), relatively complete, and well-constrained by radiometric ages, as a potential candidate for Permo-Triassic astrostratigraphy in the mid-latitude of NE Pangea. 10 low-order cycles (LCs) are defined by their dominant depositional environments and prominent cycle boundaries. Upper Gzhelian-mid Sakamarian Lower, Middle, and Upper Daheyan LCs are composed mainly of meandering and braided stream deposits, formed during initial and early rifting. The Upper Daheyan LC contains mature Calcisols, indicating a subhumid-semi-arid climatic change. They were transgressed conformably by lake-margin, deltaic, and profundal deposits of the mid-Sakamarian-Artinskian Lucaogou and Hongyanchi LCs, indicating rapid graben subsidence. Contrasting lithologies suggest highly-fluctuating arid-subhumid conditions at the intermediate and high-order cycle scales. The two LCs are separated by a fluvial-incision and correlative deltaic downlap surface, indicating an uplifting event. Lake regression and fluvial peneplanation at the end of Hongyanchi LC is indicated by fluvial erosion and deposition of the thin (1-10s m) Lower Quanzijie LC, suggesting a tectonic uplift and/or climatic change. The basal two mature Calcisols and top Gleysols of the Upper Quanzijie LC containing fluvial and loess (?) deposits indicate an arid-to-humid climatic change. The two Quanzijie LCs span over Kungurian (?)-Capitanian ages and signify the beginning of late rifting. The humid condition magnified in overlying thick (~800 m) Lopingian-lower Induan Wutonggou LC, composed of deltaic, lake-margin, and meandering stream deposits. The overlying fluvial-lake margin deposits of the Induan Jiucaiyuan LC indicate a combination of tectonic uplift and a climatic

  20. Measuring crustal convergence using rock exhumation along the complex glaciated Chugach Mountains, southeast Alaska (United States)

    Spotila, J. A.; Buscher, J.


    Rates of rock uplift often constrain magnitudes of convergent plate motion in collisional settings. In complex orogenic belts, however, these rates can be difficult to measure. In southeast Alaska, a rapidly-evolving mountain system is centered at a syntaxial bend in the Pacific-North American plate boundary. Rugged topography of the Chugach Mountains stretches for more than 500 km along the hanging wall of the Aleutian Trench, above a colliding microplate, and as coast ranges along the Queen Charlotte-Fairweather transform fault. At each segment of the plate boundary, crustal convergence within North America should vary according to the obliquity of plate motion and the degree of underthrusting. Geodetic and neotectonic studies of rapidly-eroding structures have yet to define rates of horizontal plate motion partitioning. Surface uplift studies, based on short term geodesy or Holocene motion of coastal landforms, are also complicated by megathrust elastic strain accumulation cycles and the viscoelastic response to recent glacial ice thinning. It is thus important to measure exhumation and the erosional transfer of mass as a proxy for the degree of upper crustal convergence accommodated by rock uplift. We have attempted to determine exhumation pattern where the highly-deformed, oceanic and continental rocks of the Yakutat microplate collide with North America. Although the total shortening rate between this microplate and North America is of the order ~3-5 cm/yr, an unconstrained magnitude of shortening is absorbed by imbricate thrust faults within it, the suture between it and North America, and within the previously accreted terranes that form the edge of the continent. We have constrained rock cooling histories as a proxy for exhumation on samples along a dense grid that spans major structural elements, including the Pamplona and Chugach-St. Elias fault systems. Apatite and zircon radiogenic helium ages provide a range in temperature sensitivity that can be used

  1. Paired moraine-dammed lakes: a key landform for glaciated high mountain areas in the tropical Andes of Peru (United States)

    Iturrizaga, Lasafam


    The tropical mountain range of the Cordillera Blanca hosts one of the main concentrations of proglacial lakes in high-mountain settings worldwide, which have formed as a result of the dominant trend of modern glacier retreat. Based on empirical data from field research in over 20 valleys and the analysis of air and satellite images, a genetic classification of major lake types with their barriers and a generalized model for the distribution of the present lakes and paleolakes was set up. The origin of the lakes and their recurrent distribution pattern are associated with the individual stages of the Pleistocene to modern glaciation and their corresponding geomorphological landforms. Characteristic repetitive moraine sequences are found in the upper parts of numerous valleys of the Cordillera Blanca. In terms of the spatial arrangement of the lake types, combined lakes are classified as a distinct composite lake type. These lakes occur at nearly the same elevation or at successively lower elevations, and form characteristic lake sequences of two or more lakes. They may occur as multi-moraine-dammed lakes or mixed combined lakes such as moraine-rock-dammed lakes or multi-debris-dammed lakes. From special interest are in this study the paired moraine-dammed lakes (e.g. Lagunas Qoyllurcochas, Lagunas Safuna Alta and Baja). They are composed of the Great Endmoraine (GEM), primarily formed during the Little Ice Age and earlier, and the pre-GEM, formed during the Holocene. Both moraines are located in rather close vicinity to each other at a distance of 1-3 km. In contrast to the prominent sharp-crested GEM, the pre-GEM is a low-amplitude end-moraine complex, which usually does not exceed a few meters to tens of meters in height. The latter is often composed of several inserted moraine ridges or an irregular hummocky moraine landscape. It is argued here that the process of formation of these combined lakes is mainly controlled by a combination of distinct topographical

  2. Carboniferous paleogeographic and paleoclimatic reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Scotese, C.R. (Univ. of Texas, Arlington, TX (United States). Dept. of Geology); Raymond, A. (Texas A and M Univ., College Station, TX (United States). Dept. Geology)


    The Carboniferous was an important transitional period in earth history. The Paleozoic oceans separating the continents of Gondwana, Laurentia, Baltica, Kazakhstan, and Siberia had closed by the late Carboniferous forming the late Paleozoic supercontinent of Pangea. Plate motions which appear to have been rapid during the Early Carboniferous (6--10 cm/yr), slowed to a temperature gradient increased as the Earth's climate changed from hot-house to ice-house conditions. Sea level, which stood high during the Early Carboniferous, fell as a result of continental collision and mountain-building, and then began to rise and fall rhythmically as the South Polar ice-cap waxed and waned. These environmental changes intersected important evolutionary events, namely, the explosive colonization of the emergent land areas by plants and the rise of terrestrial vertebrates. In this paper the authors present paleogeographic reconstructions for 6 intervals during the Carboniferous. These maps illustrate the latitudinal position of the continents deduced from paleomagnetic data and the distribution of climatically restricted lithofacies (coal, bauxite, evaporite, calcrete, and tillite), the inferred location of active plate boundaries, and the changing configuration of mountains, land, shallow seas, and deep ocean basins. For each of these paleogeographic maps a climatic simulation was run using the Parametric Climate Model. These simulations predict the distribution of high and low pressure cells, prevailing wind directions, pole-to-equator temperature gradient, relative wetness/dryness, as well as zones of coastal upwelling.

  3. 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


    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.

  4. Paleoenvironmental changes recorded in a luminescence dated loess/paleosol sequence from the Tianshan Mountains, arid central Asia, since the Penultimate Glaciation (United States)

    Li, Guoqiang; Rao, Zhiguo; Duan, Yanwu; Xia, Dunsheng; Wang, Leibin; Madsen, David B.; Jia, Jia; Wei, Haitao; Qiang, Mingrui; Chen, Jianhui; Chen, Fahu


    Mid-latitude arid central Asia (ACA) is one of the driest regions in the world and is a key source area of global atmospheric dust. Loess records of paleoclimatic changes in ACA are complex and interpretations are problematic due primarily to the lack of robust chronologies. Quartz OSL and K-feldspar pIRIR dating methods were employed to date 8 quartz and 30 K-feldspar samples from a 30 m loess sequence (BYH10 section) on the northern slope of the Tianshan Mountains, central ACA, northwest China. The reliability of quartz and K-feldspar ages was monitored by internal checks of luminescence characteristics and by comparison of the quartz and K-feldspar ages. The section lithology, proxy indexes of grain size and magnetic susceptibility, and the high resolution OSL chronology together indicate: (1) Quartz OSL dating can be used to date ACA loess samples less than 40 ka, while K-feldspar pIRIR dating is reliable for loess samples at least as old as ∼150 ka from ACA; (2) Aeolian loess began to be deposited on the northern slope of Tianshan Mountains beginning at least ∼145 ka ago, and was deposited primarily during the penultimate and last glaciation periods; (3) Rapid loess deposition occurred during MIS 6, MIS 4 to early-mid MIS 3, and MIS 2, but little or no loess deposition occurred during MIS 5, MIS 3a and MIS 1; (4) This loess depositional sequence is comparable to previously published stalagmite growth records in the region on glacial-interglacial cycles. Rapid dust deposition and lack of stalagmite growth during glacials, and lack of loess deposition and stalagmite growth during interglacials, indicate a climatic pattern of wet-warm (interglacial) and dry-cold (glacial) climatic regimes on orbital cycles in ACA; (5) Variation in the loess deposition rates in ACA was much larger than in the central loess plateau during the last glaciation; (6) Depositional hiatuses of >50 kyr occur in ACA loess sequences, and high resolution chronologies are needed when

  5. Chronology of glaciations in the Cantabrian Mountains (NW Iberia) during the Last Glacial Cycle based on in situ-produced 10Be (United States)

    Rodríguez-Rodríguez, Laura; Jiménez-Sánchez, Montserrat; Domínguez-Cuesta, María José; Rinterknecht, Vincent; Pallàs, Raimon; Bourlès, Didier


    The mountain ranges of the Iberian Peninsula preserve a valuable record of past glaciations that may help reconstruct past atmospheric circulation patterns in response to cooling events in the North Atlantic Ocean. Available chronologies for the glacial record of the Cantabrian Mountains, which are mainly based on radiocarbon and luminescence dating of glacial-related sediments, suggest that glaciers recorded their Glacial Maximum (GM) during MIS 3 and experienced a later Last Glacial Maximum (LGM) advance. This LGM extent is not established yet, preventing a fair correlation with available Cosmic Ray Exposure (CRE) based chronologies for the glacial record of the Pyrenees and the Sistema Central. We present a glacial reconstruction and a 10Be CRE chronology for the Porma valley, in the southern slope of the central Cantabrian Mountains. Glacial evidence at the lowest altitudes correspond to erratic boulders and composite moraines whose minimum 10Be CRE age of 113.9 ± 7.1 ka suggests that glaciers were at their maximum extent during MIS 5d, most likely in response to the minima in summertime insolation of the Last Glacial Cycle. Recessional moraines preserved within the glacial maximum limits allow the assessment of subsequent glacier advances or stagnations. The most remarkable advance took place prior to 55.7 ± 4.0 ka (probably at the end of MIS 4), consistently with minimum radiocarbon ages previously reported for lacustrine glacial-related deposits in the Cantabrian Mountains. A limited number of 10Be CRE ages from a composite moraine suggest a possible advance of the Porma glacier coeval with the global LGM; the glacier front attributed to the LGM would be placed within the margins of the previous GM like in the western Pyrenees. Erratic boulders perched on an ice-moulded bedrock surface provided a mean 10Be CRE age of 17.7 ± 1.0 ka, suggesting that part of the recessional moraine sequence corresponds to minor advances or stagnations of the glacier fronts

  6. Increasing risks related to landslides from degrading permafrost into new lakes in de-glaciating mountain ranges (United States)

    Haeberli, Wilfried; Schaub, Yvonne; Huggel, Christian


    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

  7. Differentiation in stag beetles, Neolucanus swinhoei complex (Coleoptera: Lucanidae): four major lineages caused by periodical Pleistocene glaciations and separation by a mountain range. (United States)

    Tsai, Cheng-Lung; Wan, Xia; Yeh, Wen-Bin


    Taxonomic debates on Neolucanus swinhoei complex consisting of N. swinhoei, N. doro doro, N. doro horaguchii, and N. euganiae, distributed exclusively in Taiwan, have been ongoing for several decades because of their overlapping morphological characters. To clarify their taxonomic status and phylogeographical history, we analyzed nine morphological characteristics and four molecular amplicons. Phylogenetic inferences based on COI+16S rDNA+wingless showed one eastern and three western lineages, with the latter consisting of one low-hill and two montane lineages. Intermingled DNA sequences from different populations within each lineage, many low FST values, and a high variance component between lineages indicate the possibility of gene flow among populations. However, positive relationships were observed between the genetic divergences of 16S rDNA and its FST values with geographic distance. A divergence estimation based on COI+16S revealed that these beetles might have originated from Asian mainland and differentiated into western and eastern lineages ca. 1Mya, with the differentiation of the western lineages occurring approximately 0.50-0.75Mya. Isolation by mountain ranges and limited flying capability of these beetles as well as populations retreat to and expansion from refugia in response to glaciation cycles have resulted in the current distribution of N. swinhoei complex. Although most morphological characters are variable and undistinguishable, multi-dimensional scaling analysis based on measurable characteristics could recognize hill N. swinhoei as a cluster distinct from the others. However, based on the realities of genetic admixture, shared phylogeographical history and overlapping characteristics, all of these stag beetles should be regarded as Neolucanus swinhoei Bates, 1866.

  8. 10Be exposure age chronology of the last glaciation of the Roháčská Valley in the Western Tatra Mountains, central Europe (United States)

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


    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.

  9. The role of Spain in the development of the reef Brachiopod faunas during the Carboniferous

    NARCIS (Netherlands)

    Winkler Prins, C.P.


    After a short introduction on the reef development during the Late Palaeozoic, the tectono-stratigraphic history of the Cantabrian Mountains (northern Spain) during the Carboniferous is discussed, with an emphasis on the tectonically active Pennsylvanian (i.e., Late Carboniferous). The reef-bearing

  10. 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 (United States)

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


    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 semiarid-subhumid conditions

  11. Conodont faunas across the mid-Carboniferous boundary from the Barcaliente Formation at La Lastra (Palentian Zone, Cantabrian Mountains, northwest Spain); geological setting, sedimentological characters and faunal descriptions


    T. I. Nemyrovska; Wagner, R.H.; Winkler Prins, C.F.; Montañez, I.


    Two different tectono-stratigraphic domains are recognised in the Cantabrian Mountains, Asturian-Leonese (Cantabrian Zone) and Palentian (Palentian Zone). The area under investigation belongs to the southern part of the Palentian Domain and attention is focused on the Upper Viséan to lowermost Bashkirian limestones at the village of La Lastra in northern Palencia. A new geological map of the Palentian Zone is accompanied by a more detailed map centred on La Lastra. The Barcaliente Limestone F...

  12. Depositional framework and regional correlation of pre-Carboniferous metacarbonate rocks of the Snowden Mountain area, central Brooks Range, Northern Alaska (United States)

    Dumoulin, J.A.; Harris, A.G.


    This report describes lithofacies, conodont biostratigraphy and biofacies, and depositional environments of Proterozoic(?) through Devonian metacarbonate rocks in the Snowden Mountain area. These rocks are correlated with successions on the Seward Peninsula and across the Brooks Range. Lithologic and paleobiogeographic data suggest that these successions formed along a single continental margin which had faunal exchange with both North America and Siberia, rather than on a series of discrete platforms juxtaposed by later tectonic events.

  13. Response of Late Carboniferous and Early Permian Plant Communities to Climate Change (United States)

    Dimichele, William A.; Pfefferkorn, Hermann W.; Gastaldo, Robert A.

    Late Carboniferous and Early Permian strata record the transition from a cold interval in Earth history, characterized by the repeated periods of glaciation and deglaciation of the southern pole, to a warm-climate interval. Consequently, this time period is the best available analogue to the Recent in which to study patterns of vegetational response, both to glacial-interglacial oscillation and to the appearance of warm climate. Carboniferous wetland ecosystems were dominated by spore-producing plants and early gymnospermous seed plants. Global climate changes, largely drying, forced vegetational changes, resulting in a change to a seed plant-dominated world, beginning first at high latitudes during the Carboniferous, reaching the tropics near the Permo-Carboniferous boundary. For most of this time plant assemblages were very conservative in their composition. Change in the dominant vegetation was generally a rapid process, which suggests that environmental thresholds were crossed, and involved little mixing of elements from the wet and dry floras.

  14. Response of Late Carboniferous and Early Permian plant communities to climate change

    Energy Technology Data Exchange (ETDEWEB)

    DiMichele, W.A.; Pfefferkorn, H.W.; Gastaldo, R.A. [Smithsonian Institute, Washington, DC (USA). National Museum of National History


    Late Carboniferous and Early Permian strata record the transition from a cold interval in Earth history, characterized by the repeated periods of glaciation and deglaciation of the southern pole, to a warm-climate interval. Consequently, this time period is the best available analogue to the Recent in which to study patterns of vegetational response, both to glacial-interglacial oscillation and to the appearance of warm climate. Carboniferous wetland ecosystems were dominated by spore-producing plants and early gymnospermous seed plants. Global climate changes, largely drying, forced vegetational changes, resulting in a change to a seed plant-dominated world, beginning first at high latitudes during the Carboniferous, reaching the tropics near the Permo-Carboniferous boundary. For most of this time plant assemblages were very conservative in their composition. Change in the dominant vegetation was generally a rapid process, which suggests that environmental thresholds were crossed, and involved little mixing of elements from the wet and dry floras.

  15. Upper Carboniferous herbaceous lycopsids

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, B.A. [University of Wales, Cardigan (United Kingdom). Dept. of Geography


    Herbaceous lycopsids are often overlooked in palaeobotanical studies because of problems of morphological interpretation and identification. The literature on Euramerican Upper Carboniferous herbaceous lycopsids is reviewed on those species referred to the genera Selaginellites, Lycopodites, Paurodendron, Carinostrobus, Miadesmia, Spencerites and the identification of some specimens is challenged. The stratigraphical range of these lycopsids and those of dispersed spores referable to them are also reviewed and suggestions are given for the relatively late appearance of many of these lycopsids in the Euramerican Coal Measures swamps. It is suggested that anisophyllous Selaginella-like lycopsids made their first appearance in the Bolsovian (ex Westphalian C) of the Saar-Lorraine intramontane basin. Evidence from studies of coal balls and dispersed spore assemblages confirm that herbaceous lycopsids were most abundantly present in open-moor communities. Certain species of these herbaceous lycopsids, the Selaginella-like ones, are included within the extant genus Selaginella Linnaeus. For this reason a number of new combinations are proposed.

  16. Future glaciation in Fennoscandia

    Energy Technology Data Exchange (ETDEWEB)

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


    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

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

    NARCIS (Netherlands)

    Adrichem Boogaert, van H.A.


    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.

  18. New lakes in de-glaciating high-mountain regions - a challenge for integrative research about hazard protection and sustainable use (United States)

    Haeberli, W.


    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

  19. The Carboniferous reefs in China

    Institute of Scientific and Technical Information of China (English)


    The Carboniferous period was a unique period for reef developments during the Late Paleozoic;however,in past years,studies dealing with the Carboniferous reefs in China were very rare.In recent years,the Carboniferous reefs were studied in detail and diverse types of reefs have been discovered in different areas of China.In these areas,the Mississippian reefs were primarily built of bryozoans and rugose corals,which were associated with various kinds of calcareous algae.During the Pennsylvanian,in South China,the reef builders were composed of the rugose coral Fomichevella and phylloid algae,whereas in North China,the reef builders were composed of Chaetetes,bryozoans and corals.There are two main reef-building communities within Carboniferous reefs in China;an algal reef-building community and a reef-building community dominated by colonial coral.No evolutionary relationships between these two types of communities can be detected,thus indicating that two different linerages of reef-building communities evolved during the Carboniferous;the former community consists of cyanobacteria,bacteria and calcareous algae,while the latter one consists of various skeletal metazoan organisms.Through careful study of the developments of Chinese Carboniferous reefs,the evidence indicates that various communities of organisms played important reef-building functions during this period.The occurrence of these metazoan framework reefs also indicates that,during the Carboniferous,most areas in China would have been dominated by the environments with a tropical or subtropical climate.

  20. Ancient glaciations and hydrocarbon accumulations in North Africa and the Middle East (United States)

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


    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 (heterogeneities within these sediments, and in analogue deposits produced by glaciations of different ages. Deglacial, Early Silurian black shale represents the most important Palaeozoic source rock across the region. Existing models do not adequately explain the temporal and spatial development of anoxia, and hence of black shale/deglacial source rocks. The origins

  1. From valley to marginal glaciation in alpine-type relief: Lateglacial glacier advances in the Pięć Stawów Polskich/Roztoka Valley, High Tatra Mountains, Poland (United States)

    Zasadni, Jerzy; Kłapyta, Piotr


    The Pięć Stawów Polskich-Roztoka Valley in the High Tatras (Western Carpathians) features typical alpine-type relief with a deeply incised glacial trough and large, compound trough head cirque. The prominent hypsographic maximum in the valley (1680-2000 m) along with a broad cirque bottom had provided a vast space for recording glacial and periglacial landforms, specifically the most recent Lateglacial advances. The valley has been intensively studied before in the context of glacial chronology. In this paper, we re-establish the post-Last Glacial Maximum (LGM) glacial chronology of the valley via detailed geomorphologic mapping, equilibrium line altitude (ELA) reconstruction, and Schmidt hammer (SH) dating, along with a critical review of previously published cosmogenic exposure age data (36Cl) and lacustrine sediment chronology. Our results indicate that the first four of the five distinguished Lateglacial stages (Roztoka I-III, Pusta I) occurred before the Bølling/Allerød (B/A) interstadial; thus, virtually the entire valley became deglaciated in course of the Oldest Dryas cold phase. A distinct reorganization of deglacial patterns from valley-type to marginal-type occurred before B/A warming when the ELA increased above the valley hypsographic maximum concentrated at the cirque bottom elevation. It shows that noticeable deglaciation step can be caused due to topographic reason with a minimal climate forcing. This points also to an important role of glaciated valley hypsography in regulating the distribution of moraines which is rarely taken into account in paleoglaciological reconstructions. We infer that glaciers vanished in the Tatra Mountains during the B/A interstadial. Later, a renewed advance during the Younger Dryas (Pusta II) formed a nearly continuous, festoon shaped pattern of moraines and rock glaciers in close distance to cirque backwalls. Furthermore, we discus some paleoenvironmental significance of the geomorphological record in the valley

  2. Pleistocene glaciation of the Biokovo Massif

    Directory of Open Access Journals (Sweden)

    Manja Žebre


    Full Text Available Biokovo massif is situated in the coastal part of the Dinaric Mountains in Croatia. Detailed morphographic and morphometric analysis of the highest parts of the massif were used to determine the extent and characteristics of Late Pleistocene glaciation. The reconstruction of glaciers and calculations of equilibrium line altitude (ELA were carried out. Our research revealed that on the north-eastern side of the highest peak Sveti Jure two cirque glaciers with an overall area of 1 km2 were formed and their ELA was 1515 m a.s.l.

  3. Cirque development and the glaciation of the Carpathians

    Directory of Open Access Journals (Sweden)

    Ian S. EVANS


    Full Text Available The moderate altitudes of the Carpathian Mountains limited glaciation to cirque and short valley glaciers, but these were widespread: well-developed cirques are found inRomania,Ukraine,SlovakiaandPoland.  The ‘marginal’ nature of glaciation means that glaciers formed first on the most favourable (shadiest and leeward mountain slopes, giving valuable indications of former wind directions (from west-northwest inRomania.  Some cirques are completely isolated from others, but several mountain ranges rose sufficiently high above snowline that glaciers and cirques developed on all slopes, as in the Retezat, Făgăraş¸ and especially the High Tatra.  However, differences in snowline (palaeo-ELA are found between different slopes there also. The Low Tatra, by contrast, are strongly asymmetric, with many north-facing cirques.

  4. Present and past glaciation on Pluto (United States)

    Howard, Alan D.; Moore, Jeffrey M.; Umurhan, Orkan M.; White, Oliver L.; Anderson, Robert S.; McKinnon, William B.; Spencer, John R.; Schenk, Paul M.; Beyer, Ross A.; Stern, S. Alan; Ennico, Kimberly; Olkin, Cathy B.; Weaver, Harold A.; Young, Leslie A.


    Modern N2 ice glaciers flow from highlands to the east of the 750 × 1400 km2 lowland of Sputnik Planum [SP] and merge with the ices of similar composition on SP. We explore the possibility that glaciation may be fed by N2 sublimation from SP followed by redeposition on the highlands. The uplands to the northeast, north, and west of SP have been erosionally sculpted into a variety of dissected terrains that feature linear depressions (valleys), locally in dendritic networks. We interpret these dissected terrains to have been carved by N2 glaciers formerly covering the uplands. Depositional glacial landforms (moraines, eskers, outwash) have not been identified, however. N2 glaciation would have a different erosional manifestation because the substrate (porous water ice and CH4-rich mantles) probably has lower density than N2, and also because of the lack of freeze-thaw weathering. If sufficiently thick (1-4 km), N2 glaciers might have experienced basal melting. Past flow of N2 glaciers from the highlands into SP may have detached and transported the prominent mountainous water ice mountains along the western border of SP.

  5. Extensive Quaternary glaciations in eastern Turkey (United States)

    Yeşilyurt, Serdar; Akçar, Naki; Doǧan, Uǧur; Yavuz, Vural; Ivy-Ochs, Susan; Vockenhuber, Christof; Schlunegger, Fritz; Schlüchter, Christian


    During cold periods in the Quaternary, global ice volume increased and as a result valley glaciers advanced and the vice versa occurred during the warm periods. Quaternary glacier fluctuations had been also recorded in the Turkish mountains. Recently, the chronology of Late Quaternary advances in the northern and western Turkish mountains was reconstructed by surface exposure dating. However, these advances in the eastern Turkey are not dated yet. In this study, we investigated paleoglaciations in Kavuşşahap Mountains, which is located to the south of Lake Van in eastern Turkey. These mountains are one of the extensively glaciated areas in Turkey. Glacial activity is evidenced by more than 20 U-shaped valleys. For instance, one of the prominent and well-preserved glacial landscapes of Turkey is situated in the Narlıca valley system. Lateral and terminal moraines in the valley system indicate more than 10 glacial advances. To build their chronology, 39 erratic carbonaceous boulders were sampled for surface exposure dating with cosmogenic 36Cl. We also reconstructed the ice margin reconstruction of the Narlıca paleoglacier using the accumulation area ratio and area-altitude balance ratio approaches. We estimated an equilibrium line altitude (ELA) of ca. 2900 m above sea level based on the maximum ice extend, which implied ca. 800 m decrease in the ELA during the Late Quaternary in comparison to the lower bound of the modern ELA estimate. The first results of the surface exposure dating will be presented.

  6. Late Pleistocene glaciation of the Mt Giluwe volcano, Papua New Guinea (United States)

    Barrows, Timothy T.; Hope, Geoffrey S.; Prentice, Michael L.; Fifield, L. Keith; Tims, Stephen G.


    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.

  7. Late Pleistocene glaciation of the Mt Giluwe volcano, Papua New Guinea (United States)

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


    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. Mountaineering

    Institute of Scientific and Technical Information of China (English)



    Most young people enjoy some forms of physical activities.It may be walking,cycling or swimming,or in wither,skating or skiing.It may be a game of some kind,football,hockey(曲棍球),golf,or tennis.Perhaps it may be mountaineering.

  9. Discussion on the Neoproterozoic glaciations in the South China Block and their related paleolatitudes

    Institute of Scientific and Technical Information of China (English)

    ZHANG QiRui; CHU XueLei; FENG LianJun


    The Kaigas, Sturtian, Marinoan, and Gaskiers glaciations are widely recognized in Neoproterozoic. However, in the South China Block only the Jiangkou (Sturtian) and Nantuo (Marinoan) are symbolized by sedimentary records. The Kaigas, recorded by isotopic and chemical proxies, exhibited likely the nature of cold paleoclimate with local mountain glaciation. The correlation of the Doushantuo Forma-tion with the Gaskiers is indicated by the carbon isotope excursion and the dated age from the interval, however the South China Block was then under non-glacial weather. With no paleomagnetic data, the position of the South China Block during the Sturtian glaciation cannot be determined. The paleolati-tudes of the South China Block during the Kaigas and Nantuo glaciations are intermediate, even though the Nantuo was once rendered erratically deduced equatorial. In fact, the paleolatitudes of the South China Block during the Neoproterozoic glaciations are all likely at about 30°-40°.

  10. The Glaciation of the Ecuadorian Andes (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).

  11. The significance of tectonism in the glaciations of Greece (United States)

    Bathrellos, George; Skilodimou, Hariklia; Maroukian, Habik


    In Greece, Middle to Late Pleistocene mountain glaciations appear to have been quite extensive, along the mountain range of Pindus, on Mt. Olympus and in the highlands of Peloponnesus. This study focuses on the Middle to Late Pleistocene glaciations based on the examination of cirque formations and their elevation changes due to vertical tectonism, in certain parts of Greece, namely Pindus, Mt. Olympus and Peloponnesus. An initial spatial database of these glacial forms was created including their location and mean elevation. Some of the glaciated sites have been taken from previous literature and others were recorded from topographic maps, air photos and field work. ArcGIS 10 software was used to process the glaciated sites. A map depicting the glaciated areas of Greek regions was compiled with over 230 cirques. A cirque's top, lip and margins of each location were mapped. So altitudes of apex and lip and mean altitude of each cirque ([apex+lip]/2), were calculated. A total number of 239 inactive cirques was recorded with limestone as the dominant lithology. As one moves to the south, in the case of Pindus range and its extension in the Peloponnesus, the number of cirques decreases. These glacial forms occur at altitudes varying from 2,770 to 1,600 m.a.s.l. Thus the preservation of ice for longer periods of time is more likely at altitudes higher than 1,600 m.a.s.l. Concerning the distribution of the mean elevations of cirques one should take into consideration the tectonic activity of the study area. Especially in the Pindus range, Mount Olympus, and Peloponnesus this process is in the form of uplift. This has increased the mean elevation of the cirques in every following ice age. So, in older times many cirques were a few hundred meters lower than the more recent glacial period.


    Directory of Open Access Journals (Sweden)



    Full Text Available Carboniferous rocks from North Karakorum display sharp lateral variations in lithology and thickness suggesting accumulation in half-grabens during continental rifting between the Karakorum block and northern Gondwana. Different Carboniferous successions, belonging to distinct tectonic units, have been detected. Thin, poorly fossiliferous successions of arenites and crinoidal limestones contrast with very thick terrigenous-carbonate successions comprising two distinct fossiliferous horizons. The lower fossiliferous horizon yielded brachiopods (Pustula sp., Rhipidomella sp., Choristites sp., Martiniopsis sp., Afghanospirifer sp., Gypospirifer sp., Composita sp. of Bashkirian age. The upper fossiliferous horizon, lying about 90 m above the former, contains corals, crinoids and brachiopods (Densepustula cf. losarensis, Dowhatania sulcata n. sp., Brachythyris sp., Rhipidomella sp., Septacamera dowhatensis, Alispirifer middlemissi of Moscovian to Kasimovian age. The Carboniferous brachiopods of North Karakorum are similar to those collected in the Late Carboniferous of Central Afghanistan, Himalaya (Manang, Spiti, Tibet, and Lhasa Block (Xainza area. 

  13. New advances in the study of Alpine glaciations

    Institute of Scientific and Technical Information of China (English)

    ShangZhe Zhou


    The European Alps is the birthplace of glaciology and in particular Quaternary glaciology and for over one hundred years has been a model region for studying mountain glaciations. In this paper, we review the achievements from this region, which will benefit glaciological studies of the Tibetan Plateau, China. According to new evidences of glaciofluvial de-posits discovered in valleys and forelands of the Alps, researchers have progressed from an original four Pleistocene gla-ciations to seven glaciations:Biber, Donua, Günz, Haslach, Mindel, Riss and Würm. The earliest one Biber possibly oc-curred between the Pliocene and Pleistocene, but the chronology before Riss is still in doubt. Recent years, Riss and Würm glaciations have been supported by a large numbers of cosmogenic exposure dating. In particular, cosmogenic nuclide exposure dating has been carried out for different moraine boulders in numerous valleys, which reveals a series of climatic change events, and they are comparable to post-glacial age records of northern Europe. The advancement of glaciological studies in the Alps is important in promoting glaciological research in the Tibetan Plateau.

  14. Periglacial landforms in the Pohorje Mountains

    Directory of Open Access Journals (Sweden)

    Karel Natek


    Full Text Available Contrary to the well-studied Pleistocene glaciation, periglacial phenomena in Slovenia have been given less scientific attention because they are not particularly evident in high mountains due to prevailing carbonate rocks. This, however, is not the case in the Pohorje Mountains: built of igneous and metamorphic rocks, it was not glaciated due to its insufficient elevation, but was subject to periglacial processes. In the article, some of the periglacial landforms of the Pohorje Mountains are presented for the first time, especially nivation hollows in the uppermost zone, and the Jezerc cirque where a smaller glacier, unknown until recently, existed at the peak of the glaciation.

  15. Shaping the Rwenzoris: balancing uplift, erosion, and glaciation (United States)

    Kaufmann, Georg; Hinderer, Matthias; Romanov, Douchko


    The Rwenzori Mountains in Africa represent an extremely uplifted basement fault block at the eastern edge of the western branch of the East African Rift system, a large-scale rift system controlled by extensional stresses. The rugged alpine topography reaches an altitude of up to 5109 m, and the highest parts are ice-covered. Glacial landforms and moraines proof repeated more extensive glaciations during the last glacial cycles. In order to elucidate magnitudes and the varying role of erosional processes in shaping the relief of the Rwenzori Mountains over the past 2 mill. years, we performed numerical simulations with the landscape evolution programme ULTIMA THULE. It is controlled by a climate driver with temperature as a master variable as well as changing precipitation and evapotranspiration over time. The morphological processes considered are fluvial erosion, hillslope diffusion, and glacial abrasion, and the latter controlled by the simulated glaciation of the landscape. We provide three sets of model runs: the first one starting from the present-day topography and running for approx. 800 ka, the second one extending the modelling period to 2 Ma, and the third one starting from a peneplain and evolving for 2 Ma. Our results provide constraints on the temperature history of the Rwenzori Mountains, the interplay of morphological degradation and tectonic uplift, and a time frame for the formation of the mountain chain from a peneplain to the present relief. The modelled landscape evolves from a peneplain 2 Ma ago to a Rwenzori-type mountain range, when the fairly strong average rock uplift of 1-2 mm year-1 is compensated by a strong fluvial erosion component. The rock uplift rate is needed to obtain elevations above the equilibrium line altitude around 500 ka BP and results in surface uplift over time. Around that time, a periodic ice cap appears in the models, and glacial abrasion then limits the height of the Rwenzori Mountains to its present elevation.

  16. Plant biodiversity changes in Carboniferous tropical wetlands

    DEFF Research Database (Denmark)

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


    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. High-temperature carbidization of carboniferous rocks (United States)

    Goldin, B. A.; Grass, V. E.; Nadutkin, A. V.; Nazarova, L. Yu.


    Processes of thermal metamorphism of carboniferous rocks have been studied experimentally. The conditions of high-temperature interaction of shungite carbon with components of the contained rocks, leading to formation of carbide compounds, have been determined. The results of this investigation contribute to the works on searching for new raw material for prospective material production.

  18. The Response of Fluvial Landscapes to Glaciation (United States)

    Brocklehurst, S. H.; Whipple, K. X.


    A major consequence of climate cooling is the growth of glaciers in mountain ranges previously sculpted by fluvial and hillslope processes. Climate change and the tectonics of mountain ranges are linked if glacial erosion either alters the relief structure, or exhumes material in a different fashion from rivers. Glacial erosion carves cirques and U-shaped valleys, and cooler climates also affect hillslope processes, as freeze-thaw, rockfall, landsliding and debris flows start to dominate. The signature of glacial erosion on the landscape is readily identified from digital elevation model (DEM) analyses, including hypsometry and longitudinal profiles, and comparison with the evolution of fluvial landscapes can be made using a landscape evolution model. These techniques demonstrate that the evolution of glaciated landscapes is not a simple function of regional climate change. In smaller drainage basins in the eastern Sierra Nevada, California, glaciers have generated modest relief, and have incised the valley floor at higher elevations. In larger drainage basins, where accumulation areas are greater and the rainshadow effect is less, glaciers have carved a strikingly different morphology. There is more relief, and valley floor incision occurs at much lower elevations. The Sangre de Cristo Range, Colorado, has evolved similarly, although with pronounced asymmetry, caused by the prevailing winds from the west. Accumulation of wind-blown snow on the eastern side of the range causes much more substantial erosion and deposition of spectacular moraines. In more tectonically active regions, such as the Southern Alps of New Zealand, and the Nanga Parbat region of Pakistan, smaller glacial valley floors steepen in response to rapid rock uplift, whereas larger glaciers maintain shallow gradients despite rapid rock uplift. Hillslope processes are apparently slower than valley floor incision, at least for some period, allowing dramatic relief production and decoupling of valley

  19. Widespread Antarctic glaciation during the Late Eocene (United States)

    Carter, Andrew; Riley, Teal R.; Hillenbrand, Claus-Dieter; Rittner, Martin


    Marine sedimentary rocks drilled on the southeastern margin of the South Orkney microcontinent in Antarctica (Ocean Drilling Program Leg 113 Site 696) were deposited between ∼36.5 Ma to 33.6 Ma, across the Eocene-Oligocene climate transition. The recovered rocks contain abundant grains exhibiting mechanical features diagnostic of iceberg-rafted debris. Sand provenance based on a multi-proxy approach that included petrographic analysis of over 275,000 grains, detrital zircon geochronology and apatite thermochronometry rule out local sources (Antarctic Peninsula or the South Orkney Islands) for the material. Instead the ice-transported grains show a clear provenance from the southern Weddell Sea region, extending from the Ellsworth-Whitmore Mountains of West Antarctica to the coastal region of Dronning Maud Land in East Antarctica. This study provides the first evidence for a continuity of widespread glacier calving along the coastline of the southern Weddell Sea embayment at least 2.5 million yrs before the prominent oxygen isotope event at 34-33.5 Ma that is considered to mark the onset of widespread glaciation of the Antarctic continent.

  20. Periglacial landforms in the Pohorje Mountains

    Directory of Open Access Journals (Sweden)

    Karel Natek


    Full Text Available Contrary to the well-studied Pleistocene glaciation, periglacial phenomena in Slovenia havebeen given less scientific attention because they are not particularly evident in high mountainsdue to prevailing carbonate rocks. This, however, is not the case in the Pohorje Mountains:built of igneous and metamorphic rocks, it was not glaciated due to its insufficient elevation,but was subject to periglacial processes. In the article, some of the periglacial landforms ofthe Pohorje Mountains are presented for the first time, especially nivation hollows in theuppermost zone, and the Jezerc cirque where a smaller glacier, unknown until recently, existedat the peak of the glaciation.

  1. Quaternary glaciation in the Nubra and Shyok valley confluence, northernmost Ladakh, India (United States)

    Dortch, Jason M.; Owen, Lewis A.; Caffee, Marc W.


    Three glacial stages (Deshkit 1, Deshkit 2 and Dishkit 3 glacial stages) are identified in the Nubra and Shyok valleys in northernmost Ladakh, northwest India, on the basis of geomorphic field mapping, remote sensing, and 10Be terrestrial cosmogenic nuclide surface exposure dating. The glacial stages date to ˜ 45 ka (Deshkit 1 glacial stage), ˜ 81 ka (Deshkit 2 glacial stage) and ˜ 144 ka (Deshkit 3 glacial stage). A mean equilibrium line altitude depression of ˜ 290 m for the Deshkit 1 glacial stage was calculated using the area accumulation ratio, toe-to-headwall ratio, area-altitude, and area-altitude balance ratio methods. Comparison of glaciation in the Nubra and Shyok valleys with glaciations in the adjacent Central Karakoram of northern Pakistan and northern side of the Ladakh Range of northern India indicates that glaciation was synchronous on Milankovitch timescales across the region during MIS-6, but differed greatly in extent, with more extensive glaciation in the Karakoram than the morphostratigraphically equivalent glaciation on the northern slopes of the Ladakh Range. This highlights the strong contrast in the extent of glaciation across ranges in the Himalaya-Tibetan orogen, necessitating caution when correlating glacial successions within and between mountain ranges.


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    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. 

  3. Cosmic Reason of Great Glaciation (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

  4. Late Amazonian Glaciations in Utopia Planitia, Mars (United States)

    Osinski, G. R.; Capitan, R. D.; Kerrigan, M.; Barry, N.; Blain, S.


    We present evidence from western Utopia Planitia, including lineated valley fill and lobate debris aprons, for widespread glaciations over a large expanse of the northern plains and dichotomy boundary during Late Amazonian times.

  5. Carboniferous paleogeographic, phytogeographic, and paleoclimatic reconstructions (United States)

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


    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

  6. Sequence-Stratigraphic Framework from the Carboniferous to the Permian Chuanshanian Epoch in Dianqiangui Basin and Its Adjacent Areas, Southwest China

    Institute of Scientific and Technical Information of China (English)

    Mei Mingxiang; Ma Yongsheng; Deng Jun; Meng Qingfen; Li Donghai


    in the Dianqiangui basin and its adjacent areas in terms of two types of facies-changing surfaces as well as two kinds of diachronism in stratigraphic records. The sequence-stratigraphic subdivisions from the Carboniferous to the Permian Chuanshanian epoch in the study area show that the duration of third-order sequences, formed in the convergent period of Pangea, is more than 10 Ma. This could reflect the elementary feature that the period of sea-level change cycles formed in a relatively quiet period of tectonic action is more than 10 Ma. And this succession shows a marked cyclicity which is supposed to be the low-latitude response to the Gondwanan glaciation in the southern hemisphere.

  7. Post-Variscan thermal history of the Moravo-Silesian lower Carboniferous Culm Basin (NE Czech Republic - SW Poland) (United States)

    Botor, Dariusz; Dunkl, István; Anczkiewicz, Aneta; Mazur, Stanisław


    Apatite fission track analysis (AFT) and zircon (U-Th)/He thermochronology (ZHe) have been carried out for a lower Carboniferous greywacke succession of the Moravo-Silesian Culm Basin in the Nízký Jeseník Mountains. The range of apparent zircon helium ages is 303-233 Ma (late Carboniferous to Early Triassic) in the eastern part of the basin, whilst they are significantly younger in the western part, ranging from 194 to 163 Ma (Early-Middle Jurassic). Apatite fission track central ages range from 152 (Latest Jurassic) to 44 Ma (Eocene), with the majority being grouped between 114 (Aptian) and 57 Ma (Paleocene). All samples experienced substantial post-depositional thermal reset; both the AFT ages and the ZHe are considerably younger than the depositional ages. The mean track length varies in the range between 12.5 and 15.4 μm. The unimodal track length distribution, the relatively short mean track length (in most samples), and their rather low standard deviation values (1.2 to 2.1 μm) indicate that their thermal history was determined by Variscan and post-Variscan heating event(s) followed by a prolonged residence in the apatite partial annealing zone in the Mesozoic and finally by cooling in the Paleogene. Geological evidence combined with thermal modeling based on AFT and ZHe data indicate that the lower Carboniferous strata had already reached maximum palaeotemperatures in the late Carboniferous, however, they were presumably later re-heated during the Permian-Triassic. Post-Variscan extensional tectonics events were responsible for high heat flow that together with Carboniferous burial could account for the reset of both thermochronometers. A major phase of cooling occurred in the Late Cretaceous. Finally, exhumation was probably faster in the Paleogene, causing the present-day exposure of the studied rocks.

  8. Lepidophloios acerosus Lindley and Hutton 1831 in the Carboniferous Cucuiova Formation, “Iron Gates” Natural Park (Banat, Romania

    Directory of Open Access Journals (Sweden)

    Popa Mihai Emilian


    Full Text Available The Carboniferous Cucuiova Formation of the Sirinia Basin, Danubian Units, in Almăj Mountains, South Carpathians, yields a highly diverse yet rare compressive flora representing significant heritage values of the “Iron Gates” Natural Park. This flora includes pteridophytes (lycopsids, sphenopsids, filicopsids and gymnosperms (pteridosperms and conifers, some of these representatives being important coal generators during the Late Carboniferous times. The facies features, distribution and paleofloral features of the Cucuiova Formation are discussed in the framework of the Sirinia Basin. The lycopsid Lepidophloios acerosus Lindley and Hutton 1831 is reported for the first time in Romania from the Cucuiova Formation in Dragosela Valley, in the central part of the “Iron Gates” Natural Park.

  9. Carboniferous coprolites from Qinhuangdao of North China

    Institute of Scientific and Technical Information of China (English)


    Here we reported the coprolites that are preserved in the dark grey silty shale of the Carboniferous Benxi Formation from Shimenzhai,Qinhuangdao,North China.The coprolites occur in a sinusoidal and ribbon-like aggregate.A coprolite granule is sesame-shaped,roundish at the terminals,equidimensional and equimorphic.It is 2.2 mm long and 0.6 mm wide.Its ventral surface appears flat,and its dorsal surface is slightly convex and has an axial furrow consisting of a string of bead-shaped pits.The coprolite granule has a directional arrangement and general equality in distribution within the aggregate.Its long axis is commonly perpendicular to the margins of the aggregate.The undigested food remains of animals and plants and the organomineral calcites with heteromorphology can be seen within the coprolite granule under photomicroscope and SEM.We deduced that a tracemaker of coprolites may be a tiny polyphagia animal similar to a modern loach or a tiny fish and that the tracemaker defecated and moved in synchronization below the interface between water and sediment.The coprolites may have a high viscidity and intensity while they were defecated.Diagenesis of feces may take place earlier and quicker than the host strata because of microbes.The lagersttte of coprolites described herein may result from the combination of many factors,such as the high content of oxygen in the Carboniferous atmosphere,the brackish lagoon in humid and tropic climate background,the low water energy,and the anoxic taphonomic environment that was lack of other animals.Further we suggested that the deoxidized color (dark grey) of host strata of coprolites may be formed in the sedimentary environment rich in oxygen and the early anoxic diagenetic environment.

  10. When do glaciated landscapes form? (United States)

    Koppes, M. N.


    Glacial erosion is a fundamental link between climate and the tectonic and surface processes that create topography. Mountain ranges worldwide have undergone large-scale modification due the erosive action of ice masses, yet the mechanisms that control the timing of this modification and the rate by which ice erodes remain poorly understood. Available data report a wide range of erosion rates from individual ice masses over varying timescales, from the modern to orogenic. Recent numerical modeling efforts have focused on replicating the processes that produce the geomorphic signatures of glacial landscapes. Central to these models is a simple index that relates erosion rate to ice dynamics. To provide a quantitative test of the links between glacial erosion, sliding and ice discharge, we examined explicitly the factors controlling modern glacier erosion rates across climatic regimes, from Patagonia to the Antarctic Peninsula. We find that modern, basin-averaged erosion rates vary by three orders of magnitude, from 1->10 mm yr-1 in Patagonia to 0.01-ELA, in accord with theories of glacial erosion. Notably, erosion rates decrease by over two orders of magnitude between temperate and polar glaciers with similar discharge rates. The difference in erosion rates between temperate and colder glaciers of similar shape and size is primarily related to the abundance of meltwater accessing the bed. Since all glaciers worldwide have experienced colder than current climatic conditions, the 100-fold decrease in long-term relative to modern erosion rates may in part reflect the temporal averaging of temperate and polar conditions over the lifecycle of these glaciers. Hence, climatic variation, more than the extent of ice cover or tectonic changes, controls the pace at which glaciers shape mountains.

  11. Nature and Timing of Quaternary glaciation in the Himalaya: Review and Speculation (United States)

    Owen, L. A.


    Reconstructions of the extent and defining the timing of Quaternary glaciation across the Himalaya is an important step towards understanding the nature of long-term (centennial-millennial scale) climate-glacier dynamics in the high mountains of Central Asia. Recent efforts, aided by extensive programs of mapping and numerical dating, are beginning to more accurately define the extent and timing of Quaternary glaciation throughout the Himalayan-Tibetan orogen. The picture that is emerging is one of complex variation in the timing and extent of glaciation within and between regions. This variation is likely controlled by regional differences in the role of the major climatic systems that influence the region over time and topographic factors. A transect across the western end of the Himalayan-Tibetan orogen, including detailed studies in the Lahul Himalaya, Zanskar, Ladakh, Hunza and the Pamir, illustrates this complexity. This transect has the potential, when examined in more detail using newly developing numerical dating, and geomorphic and sedimentologic methods, to derive high-resolution records of glaciation that will help in understanding the complex relationship between climate-glacier dynamics and topography.

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

    Directory of Open Access Journals (Sweden)

    Julien Denayer


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

  13. Chronology of Tropical Glaciation from Cosmogenic Dating (United States)

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


    Moraines from multiple glaciations dating back more than a million years are preserved in deglaciated valleys bordering the Junin Plain in the Peruvian Andes. We have used cosmogenic dating (10Be) of boulders on moraines in Alcacocha Valley (S 11° 03', W 75° 58', elev. ~4100-4800 m) to identify deposits ranging in age from the last glaciation (~12-33 ka) to >1.5 Ma. This may be the longest and most detailed record of tropical glaciation yet produced. In Alcacocha Valley, lateral moraines of several older glaciations are considerably larger and extend farther downvalley than end moraines of the last glacial maximum. Preservation of the older moraines and of polished surfaces on some old boulders argues for extremely low boulder erosion rates. We estimate a maximum erosion rate of ~0.3 m/Myr, which approaches published rates for Antarctica and suggests that aridity is important in slowing boulder erosion. Our findings are consistent with results from other Andean locations, such as the Cordillera Real in Bolivia, where moraines of older glaciations are also more extensive than those of the last glacial maximum. Tectonics, climate, or a combination of both may have been responsible for the apparent decrease in glacial extent and ice volume in the Junin Plain during the Quaternary. A late Tertiary pulse of tectonism may have resulted in an increase in high-elevation topography in the Junin region, allowing growth of large ice masses. The subsequent trend in decreasing ice volume could have been caused by either a decrease in the area of high-elevation topography through glacial erosion or a decrease in the amplitude of climate variability. These hypotheses could be tested by analyzing the sediment record preserved in the Junin basin.

  14. Carboniferous paleogeographic, phytogeographic, and paleoclimatic reconstructions

    Energy Technology Data Exchange (ETDEWEB)

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


    Two revised paleographic 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, Indo-China, 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. In addition, we have constructed paleoclimatic maps for the two Carboniferous time intervals. 125 references.

  15. Persistence of Late Carboniferous tropical vegetation during glacially driven climatic and sea-level fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Di Michele, W.A.; Pfefferkorn, H.; Phillips, T.L. [Smithsonian Institution, Washington, DC (United States). Dept. of Paleobiology


    The Late Carboniferous glaciation reached its peak during the latter part of the Westphalian. In the tropical Illinois basin this was the time of deposition of the Carbondale and lower Modesto Formations, characterized by the cyclic repetition of major coal deposits, black shales, limestone, gray shales and sandstones. These lithological changes evidence repeated major fluctuations in climate and sealevel. Floras from coals, known from coal balls and palynology, characteristically were composed of three major plant communities: the wettest sites were dominated by monocarpic lycopsids, intermediate sites were dominated by polycarpic lycopsids, and areas subject to fires and intermittent flooding were dominated by medullosans and the small lycopsid Paralycopodites. Clastic-substrate environments were dominated by ferns and pteridosperms and conform to a single biozone, indicating their compositional unit and distinctness from earlier and later assemblages. The composition of lowland floras is poorly known from times between the deposition of coals and associated terrestrial rocks, intervals during which most of the lowlands were flooded and marine rocks were being deposited. Consequently, the temporally intermittent recurrence of lowland floras despite repeated, widespread environmental disruption may be explained either by vegetational persistence and migration of floras, or repeated disruption and reassembly. Several lines of evidence suggest persistence as a likely explanation.

  16. Influence of pre-Mississippian paleogeology on Carboniferous Lisburne Group, Arctic National Wildlife refuge, northeastern Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Watts, K.F.; Carlson, R.; Imm, T.; Gruzlovic, P.; Hanks, C.


    The Carboniferous Lisburne Group of northern Alaska formed an extensive carbonate platform, which was later deformed as part of the Brooks Range fold and thrust belt. In the northeast, the Lisburne Group is parautochthonous and analogous to that at Prudhoe Bay. The Lisburne's paleogeography and facies relationships pertain to assessment of the petroleum potential of the Arctic National Wildlife Refuge (ANWR). The Franklinian paleogeology, unconformably underlying the Ellesmerian sequence, has influenced sedimentation patterns in the Lisburne Group. The transgressive Endicott Group (Kekiktuk Conglomerate and Kayak, Shale) and Lisburne Group thin northward over Franklinian basement highs. In the Sadlerochit Mountains, the Katakturuk Dolomite formed a paleotopographic high over which the Endicott Group inched out and the Lisburne Group thinned. Shallow-marine oolitic grainstone developed in the cyclic Pennsylvanian Wahoo Limestone.

  17. Arsenic stress after the Proterozoic glaciations. (United States)

    Fru, Ernest Chi; Arvestål, Emma; Callac, Nolwenn; El Albani, Abderrazak; Kilias, Stephanos; Argyraki, Ariadne; Jakobsson, Martin


    Protection against arsenic damage in organisms positioned deep in the tree of life points to early evolutionary sensitization. Here, marine sedimentary records reveal a Proterozoic arsenic concentration patterned to glacial-interglacial ages. The low glacial and high interglacial sedimentary arsenic concentrations, suggest deteriorating habitable marine conditions may have coincided with atmospheric oxygen decline after ~2.1 billion years ago. A similar intensification of near continental margin sedimentary arsenic levels after the Cryogenian glaciations is also associated with amplified continental weathering. However, interpreted atmospheric oxygen increase at this time, suggests that the marine biosphere had widely adapted to the reorganization of global marine elemental cycles by glaciations. Such a glacially induced biogeochemical bridge would have produced physiologically robust communities that enabled increased oxygenation of the ocean-atmosphere system and the radiation of the complex Ediacaran-Cambrian life.

  18. Arsenic stress after the Proterozoic glaciations (United States)

    Chi Fru, Ernest; Arvestål, Emma; Callac, Nolwenn; El Albani, Abderrazak; Kilias, Stephanos; Argyraki, Ariadne; Jakobsson, Martin


    Protection against arsenic damage in organisms positioned deep in the tree of life points to early evolutionary sensitization. Here, marine sedimentary records reveal a Proterozoic arsenic concentration patterned to glacial-interglacial ages. The low glacial and high interglacial sedimentary arsenic concentrations, suggest deteriorating habitable marine conditions may have coincided with atmospheric oxygen decline after ~2.1 billion years ago. A similar intensification of near continental margin sedimentary arsenic levels after the Cryogenian glaciations is also associated with amplified continental weathering. However, interpreted atmospheric oxygen increase at this time, suggests that the marine biosphere had widely adapted to the reorganization of global marine elemental cycles by glaciations. Such a glacially induced biogeochemical bridge would have produced physiologically robust communities that enabled increased oxygenation of the ocean-atmosphere system and the radiation of the complex Ediacaran-Cambrian life.

  19. Plant biodiversity changes in Carboniferous tropical wetlands (United States)

    Cleal, C. J.; Uhl, D.; Cascales-Miñana, B.; Thomas, B. A.; Bashforth, A. R.; King, S. C.; Zodrow, E. L.


    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 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-scale (within an area of c. 0.1 ha) species diversity in South Wales of 16 ± 7 and Simpson Diversity Indices of 4.53 ± 2.55, which are very similar to values obtained from studies on North American coal swamp vegetation. Landscape diversity (within an area 105 km2) varied between 50 and 100 species in the lower to middle Westphalian Stage, falling to about 40-50 species in the upper Westphalian Stage. Regional-scale diversity (within an area > 105 km2) is difficult to estimate but was at least 120 species. Species turn-over was typically very low, at about 4 species per million years, but there were a number of intervals of more rapid species turn-over in the early Langsettian, late Duckmantian, early Bolsovian and middle Asturian times, which are recognised today as biozonal boundaries. The swamps were mostly subject to ecological stasis during early and middle Westphalian times, although they contracted locally in response to drying of substrates. Later in Westphalian times, however, the swamps were subject to regional-scale changes in composition and aerial extent, probably in response to climate change. The coal swamps had a much lower species diversity compared to modern-day tropical rain forests.

  20. Identification of Carboniferous (320 million years old) class Ic amber. (United States)

    Bray, P Sargent; Anderson, Ken B


    The presence of amber, the fossil form of the resins produced by many types of higher plants, has been reported from many localities in Mesozoic and Cenozoic rocks. We have found Class I (polylabdanoid) amber in Carboniferous sediments dating to approximately 320 million years ago. This result demonstrates that preconifer gymnosperms evolved the biosynthetic mechanisms to produce complex polyterpenoid resins earlier than previously believed and that the biosynthetic pathways leading to the types of polylabdanoid resins that are now typically found in conifers and those now typically found in angiosperms had already diverged by the Carboniferous.

  1. Paraglacial dynamics in Little Ice Age glaciated environments in the Iberian Peninsula (United States)

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


    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.

  2. The genesis of early Carboniferous adakitic rocks at the southern margin of the Alxa Block, North China (United States)

    Xue, Shuo; Ling, Ming-Xing; Liu, Yu-Long; Zhang, Hong; Sun, Weidong


    Adakite is a highly debated petrologic term that was originally proposed to describe igneous rocks formed by slab melting. Subsequent studies reported other ways to generate adakitic signatures such as the melting of mafic lower continental crust and fractional crystallization of basaltic magma. We studied adakitic rocks from the Taohuala Mountain at the southern margin of the Alxa Block, North China. These rocks are characterized by high Sr concentrations (300-450 ppm), high Sr/Y (20-75 ppm) and (La/Yb)N (25-67 ppm) ratios, and low Y (diagram, combined with their high (87Sr/86Sr)i ratios (0.7113-0.7131) and low εNd(t) (- 15.8 to - 16.8) and εHf(t) (- 18 to - 10) values of zircon, indicates that the adakitic rocks formed by partial melting of thickened continental crust. U-Pb dating of zircons using LA-ICP-MS yields an early Carboniferous age of 330 ± 5 Ma. The ages and spatial distribution of magmatic rocks indicate that the Paleo-Asian oceanic crust subducted towards the Alxa Block in the late Paleozoic. Subsequently, northward slab rollback occurred during the Carboniferous. Therefore, we propose that the adakitic rocks from the Taohuala Mountain formed by partial melting of previously thickened lower continental crust, induced by the upwelling of asthenospheric mantle during slab rollback.

  3. Glaciation and topographic evolution of the Central Patagonian Andes since 6 Ma (United States)

    Christeleit, E. C.; Laemel, R.; De Wolf, W. E.; Shuster, D. L.; Brandon, M. T.


    New and existing thermochronological data are used to model glacial erosion and topographic evolution of the central Patagonian Andes (~47S) over the last 6 Ma. The modern Andes are cut by large valleys and fjords with local valley relief of at least 2.5 km. It is currently thought that a formerly uniformly high Andes was 'buzzed' down to the elevation of the equilibrium line altitude, presumably in the last 2 Ma concurrent with late Cenozoic global cooling. However, studies of glacial debris show that glaciers were present in Patagonia as early as 6 Ma. The extent of these early glaciations is unclear, but recent work suggests that glacial valleys in the central Patagonian Andes were carved at a steady rate beginning at 6 Ma, implying that valley incision may be an important process in the topographic evolution of glaciated mountain ranges, rather than cirque retreat. To understand how valley relief has formed in the Andes, we dated 30 samples from Steffen Fjord in Chile using apatite (U-Th)/He thermochronology. We use this new data and existing thermochronological data in the region to estimate the topographic form of the central Andes at 6 Ma and model how the valley relief has evolved since the initiation of glaciation using Pecube.

  4. The timing of Late Pleistocene glaciation at Mount Wilhelm, Papua New Guinea (United States)

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


    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.

  5. Three dwarf lycophytes from the Carboniferous of Argentina*)

    NARCIS (Netherlands)

    Archangelsky, S.; Azcuy, C.L.; Wagner, R. H.


    Impressions of the bark of two small lycophytes, Bumbudendron paganzianum gen. et sp. nov. and Bumbudendron nitidum sp. nov., are described from middle Carboniferous shales in the Sierra de Paganzo. Lepidodendroid leaf cushions with a well-developed leaf scar showing a single trace, and the presence

  6. Late Carboniferous to Late Permian carbon isotope stratigraphy

    DEFF Research Database (Denmark)

    Buggisch, Werner; Krainer, Karl; Schaffhauser, Maria


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

  7. Archaeocidaris M’Coy (Echinoidea) from the Carboniferous of Egypt

    NARCIS (Netherlands)

    Lewis, D.N.; Donovan, S.K.


    Collections in museums usually have boxes of specimens which remain ‘undiscovered’ and yet which may be of importance or interest. The recent rediscovery of specimens of Archaeocidaris in the Nationaal Natuurhistorisch Museum, Leiden, from the Carboniferous of Egypt illustrates this point. These spe

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

    NARCIS (Netherlands)

    Boersma, Kerst Th.


    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

  9. Lateral weathering gradients in glaciated catchments (United States)

    McGuire, K. J.; Bailey, S. W.; Ross, D. S.; Strahm, B. D.; Schreiber, M. E.


    Mineral dissolution and the distribution of weathering products are fundamental processes that drive development and habitability of the Earth's critical zone; yet, the spatial configuration of these processes in some systems is not well understood. Feedbacks between hydrologic flows and weathering fluxes are necessary to understanding how the critical zone develops. In upland glaciated catchments of the northeastern USA, primary mineral dissolution and the distribution of weathering products are spatially distinct and predictable over short distances. Hillslopes, where shallow soils force lateral hydrologic fluxes through accumulated organic matter, produce downslope gradients in mineral depletion, weathering product accumulation, soil development, and solute chemistry. We propose that linked gradients in hydrologic flow paths, soil depth, and vegetation lead to predictable differences in the location and extent of mineral dissolution in regolith (soil, subsoil, and rock fragments) and bedrock, and that headwater catchments within the upland glaciated northeast show a common architecture across hillslopes as a result. Examples of these patterns and processes will be illustrated using observations from the Hubbard Brook Experimental Forest in New Hampshire where laterally distinct soils with strong morphological and biogeochemical gradients have been documented. Patterns in mineral depletion and product accumulation are essential in predicting how ecosystems will respond to stresses, disturbance, and management.

  10. 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.


    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,

  11. Influence of pre-Mississippian paleogeology on Carboniferous Lisburne Group, Arctic National Wildlife Refuge, northeastern Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Watts, K.F.; Carlson, R.; Imm, T.; Gruzlovic, P.; Hanks, C.


    The Carboniferous Lisburne Group of northern Alaska formed an extensive carbonate platform, which was later deformed as part of the Brooks Range fold and thrust belt. In the northeast, the Lisburne Group is parautochthonous and analogous to that at Prudhoe Bay. The Lisburne's paleogeography and facies relationships pertain to assessment of the petroleum potential of the Arctic National Wildlife Refuge (ANWR). The Franklinian paleogeology, unconformably underlying the Ellesmerial sequence, has influenced sedimentation patterns in the Lisburne Group. The transgressive Endicott Group (Kekiktuk conglomerate and Kayak Shale) and Lisburne Group thin northward over Franklinian basement highs. In the Sadlerochit Mountains, the Katakturuk Dolomite formed a paleotopographic high over which the Endicott Group pinched out and the Lisburne Group thinned. Shallow-marine oolitic grainstone developed in the cyclic Pennsylvanian Wahoo Limestone. To the south in the Shublik Mountains, a repeated sequence of Katakturuk Dolomite and the Nanook Limestone were lower, so the Endicott Group lapped over the area and was later overlain by comparable Lisburne Group rocks. In the Fourth Range, the Lisburne Group is thicker and limestones also occur in the upper Endicott Group. Oolitic grainstone in the Wahoo Limestone is rare, and broad ooid shoals apparently pinched out into deeper water carbonates on a southward sloping carbonate ramp.

  12. Pleistocene glaciation of the King Valley, Western Tasmania, Australia (United States)

    Fitzsimons, Sean J.; Colhoun, Eric A.


    Analysis of the geomorphology, geology, and palynology of deposits in the King Valley permits the identification of four glaciations and two interglaciations and has led to a revision of the Pleistocene stratigraphy of the West Coast Range. The oldest late-Cenozoic deposits in the valley appear to predate glaciation, contain extinct pollen types, and are probably of late-Tertiary age. Overlying deposits of the Linda Glaciation show intense chemical weathering and have a reversed detrital remanent magnetization indicating deposition before 730,000 yr B.P. The highly weathered tills are conformably overlain by organic deposits of the Regency Interglaciation which show a transition from montane scrub rainforest to lowland temperate rainforest. Deposits formed during the later Moore Glaciation record advances of the King Glacier and glaciers from the West Coast Range. A pollen-bearing fluvial deposit records an interstade during this glaciation. On the basis of weathering rinds, amino acid dating, and palaeomagnetism the deposits are estimated to have formed between 730,000 and 390,000 yr B.P. The Moore Glaciation deposits are overlain by sediments of the Henty Glaciation which are believed to predate 130,000 yr B.P. These deposits record multiple advances of the King Glacier and the development of a large lake during an interstade. Deposits of the subsequent Pieman Interglaciation consist of organic fine sands and silts that record a lowland scrub rainforest. Deposits of the last (Margaret) glaciation are restricted to small areas in the northern part of the valley. Although the most recent ice advance culminated after 19,000 yr B.P., evidence of older deposits of the Margaret Glaciation suggests that an early last-glaciation ice advance may have occurred. When combined with earlier studies, the recent work in the King Valley has provided one of the more complete records of Pleistocene glaciation in the Southern Hemisphere. Comparison of the deposits with the record

  13. Carboniferous Psammichnites: Systematic re-evaluation, taphonomy and autecology (United States)

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


    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 Mele??ndez 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 Psammichnites by having median dorsal holes or protruding mounds. The presence of mounds or holes in P. grumula suggests 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 Carboniferous tidal

  14. Regional mid-Pleistocene glaciation in central Patagonia (United States)

    Hein, Andrew S.; Cogez, Antoine; Darvill, Christopher M.; Mendelova, Monika; Kaplan, Michael R.; Herman, Frédéric; Dunai, Tibor J.; Norton, Kevin; Xu, Sheng; Christl, Marcus; Rodés, Ángel


    Southern South America contains a glacial geomorphological record that spans the past million years and has the potential to provide palaeoclimate information for several glacial periods in Earth's history. In central Patagonia, two major outlet glaciers of the former Patagonian Ice Sheet carved deep basins ∼50 km wide and extending over 100 km into the Andean plain east of the mountain front. A succession of nested glacial moraines offers the possibility of determining when the ice lobes advanced and whether such advances occurred synchronously. The existing chronology, which was obtained using different methods in each valley, indicates the penultimate moraines differ in age by a full glacial cycle. Here, we test this hypothesis further using a uniform methodology that combines cosmogenic nuclide ages from moraine boulders, moraine cobbles and outwash cobbles. 10Be concentrations in eighteen outwash cobbles from the Moreno outwash terrace in the Lago Buenos Aires valley yield surface exposure ages of 169-269 ka. We find 10Be inheritance is low and therefore use the oldest surface cobbles to date the deposit at 260-270 ka, which is indistinguishable from the age obtained in the neighbouring Lago Pueyrredón valley. This suggests a regionally significant glaciation during Marine Isotope Stage 8, and broad interhemispheric synchrony of glacial maxima during the mid to late Pleistocene. Finally, we find the dated outwash terrace is 70-100 ka older than the associated moraines. On the basis of geomorphological observations, we suggest this difference can be explained by exhumation of moraine boulders.

  15. Remagnetization of Lower Carboniferous Carbonates, Northeastern Ireland: Preliminary Paleomagnetic Results (United States)

    Pannalal, S. J.; Symons, D. T.; Stanley, G.; Sangster, D. F.


    Conodont color alteration index (CAI) values provide indirect paleotemperature estimates for rocks that have been subjected to a thermal event either by burial metamorphism or by hot hydrothermal fluids. Extensive CAI studies have been conducted on the Lower Carboniferous carbonates of Ireland that are host to the major sedimentary lead and zinc deposits in the Irish ore field. The CAI values show that these rocks have been affected by a regional thermal event with a decreasing trend from south (CAI=7.0) to north Ireland (CAI=1). In addition, the relative timing of the regional metamorphic event and ore mineralization in the Irish ore field, critical to the much debated genetic theories for ore genesis, has remained elusive. A paleomagnetic study, that includes thermal and alternating-field demagnetization and isothermal remanence procedures, has been conducted on 235 specimens representing 18 sites from Lower Carboniferous carbonates (CAI age than the A component and may indicate a secondary magnetization, likely the result of weathering of the carbonates by oxidizing fluids. In addition, this regional hydrothermal event may also be related to the observed CAI values in Lower Carboniferous carbonates of northeastern Ireland.


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    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. 

  17. Changes in tropical Late Carboniferous compression floras and their causes

    Energy Technology Data Exchange (ETDEWEB)

    Pfefferkorn, H.W. (Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Geology)


    In the Late Carboniferous ten biostratigraphic boundaries can be recognized based on compression floras. Some of these boundaries coincide with classical stage boundaries whereas others do not. These boundaries are observable throughout Eurameria. In most cases the same species are involved in North America and Europe. Four boundaries are characterized by extinction events that involve only a few or many taxa. Four boundaries are characterized by origination of single taxa or by changes in the dominance of taxonomic groups. Two boundaries near the base of the Late Carboniferous seem to coincide with different stages in the onset of the ice age on Gondwanaland. However, it has not been clearly demonstrated what the local climatic signals in the tropics were. Three boundaries in the late Late Carboniferous are connected with well established trends toward dryer climate. It appears that many of these floral changes were climatically controlled. The actual triggering condition seems to have been produced by a variable combination of short term (allocyclic) and long term (orogeny, continental movement) effects. In one case the reason for the extinction is not obvious and could be biotic in nature.

  18. The Devonian Lower Carboniferous succession in Northwest Peninsular Malaysia (United States)

    Meor, Hakif Hassan; Lee, Chai Peng


    A new stratigraphic nomenclature is proposed for the approximately 600 m thick, mainly clastic transitional sequence between the underlying Mempelam Limestone and overlying Kubang Pasu/Singa Formation in northwest Peninsular Malaysia. This sequence represents shallow marine deposits of the continental margin of the Sibumasu Terrane during the Middle Palaeozoic (Devonian-Carboniferous). It is separated into several formations. The Timah Tasoh Formation is an approximately 76 m sequence consisting of 40 m of laminated tentaculitid shales at the base, containing Monograptus yukonensis Jackson and Lenz and Nowakia (Turkestanella) acuaria Alberti, giving an Early Devonian (Pragian-Emsian) age, and about 36 m of rhythmically interbedded, light coloured argillo-arenites. The Chepor Formation is about 90 m thick and consists mainly of thick red mudstone interbedded with sandstone beds, of Middle to Late Devonian age. A new limestone unit is recognized and named the Sanai Limestone, which contains conodonts of Famennian age. The Binjal Formation consists of red and white mudstone interbedded with sandstone beds showing Bouma sequences. The Telaga Jatoh Formation is 9 m thick and consists mainly of radiolarian chert. The Wang Kelian Formation is composed of thick red mudstone beds interbedded with silty sandstone, and contain fossils indicative of an Early Carboniferous (Visean) age. The succession was deposited on the outer shelf, with depositional environments vertically fluctuating from prodelta to basinal marine. The Devonian-Carboniferous boundary is exposed at Hutan Aji and Kampung Guar Jentik, and indicates a major regressive event during the latest Devonian.

  19. Carboniferous-Permian rugose coral Cyathaxonia faunas in China

    Institute of Scientific and Technical Information of China (English)


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

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

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


    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

  1. Glacial effects limiting mountain height. (United States)

    Egholm, D L; Nielsen, S B; Pedersen, V K; Lesemann, J-E


    The height of mountain ranges reflects the balance between tectonic rock uplift, crustal strength and surface denudation. Tectonic deformation and surface denudation are interdependent, however, and feedback mechanisms-in particular, the potential link to climate-are subjects of intense debate. Spatial variations in fluvial denudation rate caused by precipitation gradients are known to provide first-order controls on mountain range width, crustal deformation rates and rock uplift. Moreover, limits to crustal strength are thought to constrain the maximum elevation of large continental plateaus, such as those in Tibet and the central Andes. There are indications that the general height of mountain ranges is also directly influenced by the extent of glaciation through an efficient denudation mechanism known as the glacial buzzsaw. Here we use a global analysis of topography and show that variations in maximum mountain height correlate closely with climate-controlled gradients in snowline altitude for many high mountain ranges across orogenic ages and tectonic styles. With the aid of a numerical model, we further demonstrate how a combination of erosional destruction of topography above the snowline by glacier-sliding and commensurate isostatic landscape uplift caused by erosional unloading can explain observations of maximum mountain height by driving elevations towards an altitude window just below the snowline. The model thereby self-consistently produces the hypsometric signature of the glacial buzzsaw, and suggests that differences in the height of mountain ranges mainly reflect variations in local climate rather than tectonic forces.

  2. Middle and Late Pleistocene glaciations in the southwestern Pamir and their effects on topography (United States)

    Stubner, Konstanze; Grin, Elena; Hidy, Alan J.; Schaller, Mirjam; Gold, Ryan D.; Ratschbacher, Lothar; Ehlers, Todd


    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 10Be exposure ages from moraine boulders and roches moutonnées in the southwestern Pamir document multiple Pleistocene glacial stages. The oldest exposure ages, , 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. Localized rapid fluvial incision and drainage network reorganization reflect the transient nature of the deglaciated landscape.

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

    NARCIS (Netherlands)

    Veen, van J.


    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 Cant

  4. On the Evolution of Glaciated Continental Margins (United States)

    Sverre Laberg, Jan; Rydningen, Tom Arne; Safronova, Polina A.; Forwick, Matthias


    Glaciated continental margins, continental margins where a grounded ice sheet repeatedly has been at or near the shelf break, are found at both northern and southern high-latitudes. Their evolution are in several aspects different from their low-latitude counterparts where eustatic sea-level variations possess a fundamental control on their evolution and where fluvial systems provide the main sediment input. From studies of the Norwegian - Barents Sea - Svalbard and NE Greenland continental margins we propose the following factors as the main control on the evolution of glaciated continental margins: 1) Pre-glacial relief controlling the accommodation space, 2) Ice sheet glaciology including the location of fast-flowing ice streams where source area morphology exerts a fundamental control, 3) Composition of the glacigenic sediments where the clay content in previous studies have been found to be important, and 4) Sea-level controlled both by eustacy and isostacy. From three case studies, 1) the western Barents Sea, 2) part of the North Norwegian (Troms), and 3) the Mid-Norwegian margin, the influence on these factors for the sea-floor morphology, sedimentary processes of the continental slope - deep sea and continental margin architecture are discussed. The pre-glacial relief of the mid-Norwegian and Troms margins relates to the onset of rifting and plate break-up from the early Cenozoic while for the SW Barents Sea, plate shear was followed by rifting. A wide zone of extended continental crust occurs offshore mid-Norway while this zone is much narrower offshore Troms leading to a more pronounced pre-glacial relief. Regarding sediment delivery and ice sheet glaciology the western Barents Sea exemplifies very high sediment input corresponding to an estimated average erosion of the source area of ~0.4 mm/yr (SW Barents Sea), much of which is related to subglacial erosion of Mesozoic - Cenozoic sedimentary rocks from large paleo-ice streams. The mid-Norwegian margin


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    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.

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

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


    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. Permo-Carboniferous gold epoch of northeast Queensland

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, C. [Australian National university, Canberra, ACT (Australia). Department of Geology and Research School of Earth Sciences; Kennedy, A.K. [Curtin University of Technology, Perth, WA (Australia). Department of Applied Physics


    The {sup 40}Ar/{sup 39}Ar and U-Pb methods of isotopic dating have been used to determine the age of alteration minerals and host rocks from a number of Permo-Carboniferous Au deposits in the Tasman Fold Belt system of northeast Queensland. There was a continuum in porphyry-style Au mineralisation from ca 330 to 290 Ma, which post-dates epithermal Au in the Eastern Basin sequence of the Drummond Basin. Porphyry-style Au at Kidston. and the Buck Reef. Ravenswood, formed at ca 330 Ma. The Red Dome and Mungana skarns were deposited at ca 320-310 Ma and ca 310 Ma. respectively The Au mineralisation at Mt Wright. and in the quartz-sulfide veins. Ravenswood. was emplaced at ca 310-305 Ma. The youngest porphyry-style Au deposit is Mt Leyshon, which probably formed at ca 290 Ma Where high-level intrusions are associated with Au, magmatism and mineralisation are. in general. essentially coeval. The age of the host rocks to the Permo-Carboniferous Au deposits is variable, and may be more than 150 million years older than the mineralisation. The plutonic-style Au deposit at Charters Towers is significantly older than the porphyry systems, and formed at ca 414 Ma. Copyright (1998) Blackwell Science Asia 64 refs., 2 tabs., 14 figs.

  8. 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))


    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.

  9. New data on the formation of Carboniferous coal balls

    Energy Technology Data Exchange (ETDEWEB)

    Scott, A.C.; Mattey, D.P.; Howard, R. [University of London, Egham (United Kingdom). Royal Holloway and Bedford New College, Dept. of Geology


    Coal balls are formed from the precipitation of carbonate minerals, predominantly calcite, from water during or immediately post-peat formation. Previous petrological studies suggest permineralization occurred at various stages during the peatificiation process by precipitation from a mixture of marine and meteoric freshwater. The geochemical studies reported here aimed to test previous theories of coal ball formation. The coal balls studied are from Upper Carboniferous and Carboniferous/Permian coal seams in Britain, United States of America, Belgium and China. Stable carbon isotopic values of calcites range from {delta}{sup 13}C of -5 to -35 parts per thousand indicating highly variable contribution of decayed organic matter to the carbonate cement. Oxygen isotopic values of delta({sup 18}) range from -3 to -15 parts per thousand suggest both marine and meteoric freshwater sources. The range, in the British coal balls in particular, with {delta}{sup 13}C ranging from -7 to -25 parts per thousand indicates the complexity of carbonate generation. Isotopic data support at least four theories of carbonate coal ball formation. This makes their absence from post-Permian coals the more puzzling and it is suggested that the overall structure of the peat may play a role.

  10. Rangewide glaciation in the Sierra Nevada, California (United States)

    Moore, James G.; Moring, Barry C.


    The 600-km-long Sierra Nevada underwent extensive Pleistocene glaciation except for its southernmost 100 km. Presently, ∼1700 small glaciers and ice masses near the crest of the range occur above 3250 m in elevation; these covered an area of ∼50 km2 in 1972. Fourteen of the largest glaciers decreased by about one half in area during the period from 1900 to 2004. Rock glaciers, generally glacial ice covered by 1–10 m of rockfall debris, occur in about the same span of the range as ice and permanent snowfields. They are, on average, lower by 200–300 m, apparently because of the insulating layer of rocky rubble that protects their internal ice from the sun’s heat and from wind. The principal Pleistocene glacial stages are the Sherwin (ca. 820 ka), Tahoe (170–130 and ca. 70 ka), Tioga (14–28 ka), and Recess Peak (13 ka). Some 7040 glacial lakes, produced primarily by quarrying from bedrock, were mostly exposed after recession of the Tioga glacial stage. The lakes largely mark the area of primary snow accumulation. Below the lower limit of the lakes, ice flowed downward into river-cut canyons, forming major trunk glaciers within the zone of ablation. The range is in general a westward-tilted block upfaulted on its east side. Therefore, the main late Pleistocene trunk glaciers (Tahoe/Tioga) west of the crest extend 25–60 km, whereas those east of the crest extend only 5–20 km. Because of higher precipitation northward, glacial features such as the toes of existing glaciers and rock glaciers, as well as the late season present-day snowline, all decrease in elevation northward. Likewise, the elevation of the lower limit of glacial lakes, an indication of the zone of snow accumulation during the late Pleistocene, decreases about the same degree. This similarity suggests that the overall climate patterns of the late Pleistocene, though cooler, were similar to those of today. The east slope glaciers show a similar northward depression, but they are ∼500

  11. Expert Panel Elicitation of Seismicity Following Glaciation in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Hora, Stephen; Jensen, Mikael (eds.)


    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.

  12. Diagenesis of Cambrian and lower Carboniferous sandstones, southwest Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Wahab, A.A.; Salem, A.M.K. [Tanta Univ., Kafr El-Sheikh (Egypt); McBride, E.F. [Univ. of Texas, Austin, TX (United States)


    Quartzose and feldspathic Cambrian and Lower Carboniferous sandstones (fluvial > marine > eolian) deposited on the Arabian shield in southwestern Sinai were not buried more than 1 to 1.5 km until Late Cretaceous and younger time, when the deepest rocks reached 2.5 km. Porosity was reduced by compaction to about 26%. Grain rearrangement was the main mechanism of compaction; intergranular pressure solution and ductile grain deformation are insignificant. Cementation by iron oxide (5%), quartz (3%), calcite (2%), kaolinite (2%) and K-feldspar (< 1%) reduced porosity to 12-15% except in silcretes and some ferricretes, where porosity was reduced to non-reservoir quality. Cements have no selectivity for certain textures or stratigraphic positions.

  13. Diagenesis of Cambrian and lower Carboniferous sandstones, southwest Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Wahab, A.A.; Salem, A.M.K. (Tanta Univ., Kafr El-Sheikh (Egypt)); McBride, E.F. (Univ. of Texas, Austin, TX (United States))


    Quartzose and feldspathic Cambrian and Lower Carboniferous sandstones (fluvial > marine > eolian) deposited on the Arabian shield in southwestern Sinai were not buried more than 1 to 1.5 km until Late Cretaceous and younger time, when the deepest rocks reached 2.5 km. Porosity was reduced by compaction to about 26%. Grain rearrangement was the main mechanism of compaction; intergranular pressure solution and ductile grain deformation are insignificant. Cementation by iron oxide (5%), quartz (3%), calcite (2%), kaolinite (2%) and K-feldspar (< 1%) reduced porosity to 12-15% except in silcretes and some ferricretes, where porosity was reduced to non-reservoir quality. Cements have no selectivity for certain textures or stratigraphic positions.

  14. Radiizonates arcuatus, a distinctive new miospore species from the Lower Carboniferous of Western Gondwana. (United States)

    Loboziak; Playford; Melo


    A new species of trilete zonate miospores, Radiizonates arcuatus, is established for Lower Carboniferous Western Gondwanan forms hitherto ascribed misguidedly to Radiizonates genuinus (Jushko) Loboziak and Alpern (1978), a Russian Lower Carboniferous species. The latter binomen is, moreover, not a valid combination and is more correctly designated as Vallatisporites genuinus (Jushko) Byvsheva, 1980. R. arcuatus is, from records to date, confined to westerly parts of Gondwana (Brazil, North Africa and Middle East), in which it is characteristic of Early Carboniferous strata, albeit with some slightly older and slightly younger occurrences.

  15. Morphometric analysis of glacial landforms in the Northern part of the Slovak High Tatra Mountains

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    Veronika KUPKOVÁ


    Full Text Available The High Tatra Mountains were glaciated during the European Last Glacial Maximum (LGM, dating back to 20 000 BP. Several studies (e.g. Midriak, 1983; Lindner et al., 2003 showed that all the main valleys, on both Slovak and Polish sides, were glaciated. We can identify glacial landforms typical of a high mountain environment: glacial cirques, complex cirques, troughs, and depositional zones. These form segments of a cascade system where ice accumulated in the upper parts (cirques and flowed down-valley. Cirque morphometric characteristics (e.g. width, length, altitude, azimuth were measured in GIS on the basis of the geomorphological map of Lukniš (1973

  16. The geology of Liébana, Cantabrian Mountains, Spain; deposition and deformation in a flysch area

    NARCIS (Netherlands)

    Maas, K.


    The Nansa-Deva map sheet of the Geological Map of the Southern Cantabrian Mountains is published. The accompanying thesis deals with the stratigraphy and structures of the Devonian, Carboniferous, Permian and Mesozoic rocks which constitute the mapped area. A condensed sequence of nodular limestones

  17. Ocean oxygenation in the wake of the Marinoan glaciation. (United States)

    Sahoo, Swapan K; Planavsky, Noah J; Kendall, Brian; Wang, Xinqiang; Shi, Xiaoying; Scott, Clint; Anbar, Ariel D; Lyons, Timothy W; Jiang, Ganqing


    Metazoans are likely to have their roots in the Cryogenian period, but there is a marked increase in the appearance of novel animal and algae fossils shortly after the termination of the late Cryogenian (Marinoan) glaciation about 635 million years ago. It has been suggested that an oxygenation event in the wake of the severe Marinoan glaciation was the driving factor behind this early diversification of metazoans and the shift in ecosystem complexity. But there is little evidence for an increase in oceanic or atmospheric oxygen following the Marinoan glaciation, or for a direct link between early animal evolution and redox conditions in general. Models linking trends in early biological evolution to shifts in Earth system processes thus remain controversial. Here we report geochemical data from early Ediacaran organic-rich black shales (∼635-630 million years old) of the basal Doushantuo Formation in South China. High enrichments of molybdenum and vanadium and low pyrite sulphur isotope values (Δ(34)S values ≥65 per mil) in these shales record expansion of the oceanic inventory of redox-sensitive metals and the growth of the marine sulphate reservoir in response to a widely oxygenated ocean. The data provide evidence for an early Ediacaran oxygenation event, which pre-dates the previous estimates for post-Marinoan oxygenation by more than 50 million years. Our findings seem to support a link between the most severe glaciations in Earth's history, the oxygenation of the Earth's surface environments, and the earliest diversification of animals.

  18. Is diatom richness responding to catchment glaciation? A case study from Cana+9dian headwater streams

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    Eugen Rott


    Full Text Available Due to global change affecting glaciers worldwide, glacial streams are seen as threatened environments deserving specific scientific interest. Glacial streams from the Coast Range and Rocky Mountains in British Columbia and at the border to Alberta were investigated. In particular glacial streams and downstream sites in the Joffré Lakes Provincial Park, a near by mountain river and two large glacial streams in the Rocky Mountains (Kootenay Range, Jasper National Park were studied. Regardless of a high variability of catchment glaciation (1 to 99% thin organic biofilms with firmly attached diatom frustules of the genera Achnanthidium, Psammothidium, Encyonema, Gomphonema and fragilaroid taxa were found in all cases. In spite of fundamentally different geological conditions between the Coast Range sites and the Rocky Mountain sites, the pioneer taxon Achnanthidium minutissimum (with a slimy long ecomorph was dominating quantitatively in most of the glacier stream samples together with the rheobiontic Hannaea arcus. Individual glacier stream samples were characterized by the dominance of Achnanthidium petersenii and Gomphonema calcifugum/Encyonema latens. The diatom community analysis (cluster analysis revealed the expected separation of glacier stream sites and sites of the lower segments of the river continuum (e.g., dominance of Diatoma ehrenbergii in the mountain river. In the Joffré area, the total species richness of turbid glacial streams close to the glacier mouth was significantly lower than in the more distant sites. The two largest glacial streams in the Rocky Mountains showed divergent results with a remarkable high species richness (43 taxa at the Athabasca River origin (Columbia Icefield and low diversity in Illecillewaet river (9 km downstream the glacier mouth. From the biogeographical point of view the dominant taxa comprised mainly widespread pioneer species coping best with the unstable conditions, while the subdominant taxa

  19. Geomorphic change in high mountains: a western Himalayan perspective (United States)

    Bishop, Michael P.; Shroder, John F.; Bonk, Radoslav; Olsenholler, Jeffrey


    Globally significant interactions between climate, surface processes, and tectonics have recently been proposed to explain climate change and mountain building. Assessing climate-driven erosion processes and geomorphic change in high-mountain environments, however, is notoriously difficult. In the western Himalaya, the coupling of climate, surface processes, and tectonics results in complex topography that frequently records the polygenetic nature of topographic evolution over the last ˜100 ka. Depending upon the erosional history of a particular landscape, temporal overprinting of geomorphic events can produce unique topographic properties which define the spatial complexity of the topography. Field work coupled with analysis of the topography using digital elevation models (DEMs) enable low- and high-frequency spatial patterns and scale-dependent properties of the topography to be detected and associated with geomorphic events caused by climate and tectonic forcing. We conducted spatial analysis of the topography at Nanga Parbat in northern Pakistan to demonstrate the utility of geomorphometry and to characterize dramatic geomorphic change over the past 100 ka. Results indicate rapid river incision, extensive glaciation, and variable denudation rates by mass movement, glaciation, and catastrophic flood flushing. Furthermore, topographic and chronologic evidence indicate that glaciation is strongly controlled by the southwestern monsoon, and that modern fluvial systems are still responding to tectonic forcing and deglaciation. Scale-dependent analysis of the topography revealed that different erosion processes uniquely alter the spatial complexity of the topography, such that the greatest mesoscale relief appears to be caused by glaciation. Collectively, our results indicate that topographic development in the western Himalaya is inherently polygenetic in nature, with glaciation, fluvial and slope processes all playing important roles at different times, and that

  20. Enigmatic Fossils from the Lower Carboniferous Shrimp Bed, Granton, Scotland. (United States)

    Zapalski, Mikołaj K; Clarkson, Euan N K


    The Lower Carboniferous (Visean) Granton Lagerstätte (Edinburgh, Scotland) is principally known for the discovery of the conodont animal, but has also yielded numerous crustaceans and other faunas. Here we report on small branching colonies, reaching 10 mm in length. They are small, erect, arborescent, and irregularly branched with predominant monopodial and dichotomous growth. They bud in a single plane. In one specimen the wall microstructure is well preserved and it is composed of evenly spaced, linear fibers, running parallel to the axis of the stems, and connected by transverse bars. We discuss possible biological affinities of these organisms; we consider algal, poriferan, hydrozoan and bryozoan affinities. The general pattern of branching, presence of fan-like structures (interpreted here as possible gonophores) and microstructure suggests affinity to Hydrozoa, affinity to non-calcifying algae is less likely. Assuming hydrozoan nature; the microstructure might suggest affinities with the extant family Solanderiidae Marshall, 1892 that possess an internal chitinous skeleton. The EDS analysis shows that fossils discussed here are preserved as phosphates. The skeletons were probably not mineralized, the presence of phosphorus suggests that the colonies were originally composed of chitin. We describe these organisms as Caledonicratis caridum gen. et sp. nov. (Solanderiidae?, Capitata?). Colonies of C. caridum gen et. sp. nov. sometimes encrust the exuviae of crustaceans, which very probably lived in fresh to brackish water thus indicating a likely habitat of Caledonicratis.

  1. Enigmatic Fossils from the Lower Carboniferous Shrimp Bed, Granton, Scotland.

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    Mikołaj K Zapalski

    Full Text Available The Lower Carboniferous (Visean Granton Lagerstätte (Edinburgh, Scotland is principally known for the discovery of the conodont animal, but has also yielded numerous crustaceans and other faunas. Here we report on small branching colonies, reaching 10 mm in length. They are small, erect, arborescent, and irregularly branched with predominant monopodial and dichotomous growth. They bud in a single plane. In one specimen the wall microstructure is well preserved and it is composed of evenly spaced, linear fibers, running parallel to the axis of the stems, and connected by transverse bars. We discuss possible biological affinities of these organisms; we consider algal, poriferan, hydrozoan and bryozoan affinities. The general pattern of branching, presence of fan-like structures (interpreted here as possible gonophores and microstructure suggests affinity to Hydrozoa, affinity to non-calcifying algae is less likely. Assuming hydrozoan nature; the microstructure might suggest affinities with the extant family Solanderiidae Marshall, 1892 that possess an internal chitinous skeleton. The EDS analysis shows that fossils discussed here are preserved as phosphates. The skeletons were probably not mineralized, the presence of phosphorus suggests that the colonies were originally composed of chitin. We describe these organisms as Caledonicratis caridum gen. et sp. nov. (Solanderiidae?, Capitata?. Colonies of C. caridum gen et. sp. nov. sometimes encrust the exuviae of crustaceans, which very probably lived in fresh to brackish water thus indicating a likely habitat of Caledonicratis.

  2. Climate dominated topography in a tectonically active mountain range (United States)

    Adams, B. A.; Ehlers, T. A.


    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The broad spatial trend in channel steepness values suggests that the locus of high rock uplift rates is coincident with the rugged range core, in a similar position as high temperature and pressure lithologies, but not in the low lying foothills as has been previously suggested by low-temperature thermochronometry. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns. We demonstrate the same topographic effects are recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on topography makes the argument of mountain range steadiness untenable in significantly glaciated settings. Furthermore, our results suggest that most glaciated Cenozoic ranges are likely still in a mode of readjustment as fluvial systems change topography and erosion rates to equilibrate with rock uplift rates.

  3. High-resolution photogrammetric surface extraction over glaciated regions from WorldView stereo pairs (United States)

    Noh, M.; Howat, I. M.; Morin, P. J.; Porter, C. C.


    The monitoring of surface change in glaciated regions such as Alaska, Greenland and Antarctica is an important pursuit in climate-related Earth Science. Repeat Digital Elevation Models (DEM) created by photogrammetric surface extraction from a time-series of stereo pairs provide an efficient and low cost means for analyzing surface change over large, remote areas. Stereo-photogrammetric DEM extraction over glaciated regions is challenging due to typically low-contrast surfaces such as ice, snow, mountain shadows and steep slopes, resulting in large feature search areas and matching failures. A method for reducing the feature search area is critical for successful and efficient DEM extraction in this terrain. The SETSM (Surface Extraction with TIN-based Search-space Minimization) algorithm is developed for overcoming these problems and performs surface extraction automatically, without any user-defined or a-priori information, such as seed DEMs, using only the sensor Rational Polynomial Coefficients (RPCs) for geometric constraints. Rotation-invariant, multi-patch Normalized Cross Correlation (NCC) is used as its basic similarity measurement. SETSM constructs a TIN (Triangular Irregular Network) in the object-space domain in order to minimize the necessary search space. It employs a pyramiding strategy that uses iteratively finer resolution TIN's to minimize the search space and uses a vertical line locus to provide precise geometric constraints for reducing the search area. As a major benefit, SETSM relatively adjusts the Rational Function Model (RFM) between stereo pairs to reduce the offset between corresponding points projected by the vertical line locus caused by RPC errors, dramatically reducing the number of matching failures. In SETSM, this offset is iteratively removed with a parabolic adjustment of the NCC solution. As a demonstration, Worldview stereo pairs for a variety of test areas in Alaska, Greenland and Antarctica are selected for creating 2m grid

  4. Northern hemisphere glaciation during the globally warm early Late Pliocene.

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    Stijn De Schepper

    Full Text Available The early Late Pliocene (3.6 to ∼3.0 million years ago is the last extended interval in Earth's history when atmospheric CO2 concentrations were comparable to today's and global climate was warmer. Yet a severe global glaciation during marine isotope stage (MIS M2 interrupted this phase of global warmth ∼3.30 million years ago, and is seen as a premature attempt of the climate system to establish an ice-age world. Here we propose a conceptual model for the glaciation and deglaciation of MIS M2 based on geochemical and palynological records from five marine sediment cores along a Caribbean to eastern North Atlantic transect. Our records show that increased Pacific-to-Atlantic flow via the Central American Seaway weakened the North Atlantic Current and attendant northward heat transport prior to MIS M2. The consequent cooling of the northern high latitude oceans permitted expansion of the continental ice sheets during MIS M2, despite near-modern atmospheric CO2 concentrations. Sea level drop during this glaciation halted the inflow of Pacific water to the Atlantic via the Central American Seaway, allowing the build-up of a Caribbean Warm Pool. Once this warm pool was large enough, the Gulf Stream-North Atlantic Current system was reinvigorated, leading to significant northward heat transport that terminated the glaciation. Before and after MIS M2, heat transport via the North Atlantic Current was crucial in maintaining warm climates comparable to those predicted for the end of this century.

  5. Quaternary glacial records in mountain regions:A formal stratigraphical approach

    Institute of Scientific and Technical Information of China (English)

    P.D.Hughes; P.L.Gibbard; J.C.Woodward


    Glacial deposits in locally-glaciated mountain regions are often expressed through their surface form and the study of these deposits constitutes a major branch of geomorphology. Studies of glacial depositional records in mountain areas have often neglected formal stratigraphical procedure resulting in an ad hoc development of quasi-stratigraphical nomenclature. Here, a formal stratigraphical procedure is recommended, since this enables a systematic approach to the subdivision of glacial deposits in mountain regions. Moreover, such an approach facilitates, in some instances, the development of a formal chronostratigraphy that can be compared to regional and global geological time scales. This is important in locally-glaciated mountain regions where glacial deposits represent one of the most important records of cold stage environments. Given that glacial landforms represent a key component of the Quaternary record, maintaining a formal link between geomorphological and geological stratigraphical procedure is a fundamental requirement of a consistent and comparable stratigraphical framework.

  6. Sedimentological and sequence stratigraphic analysis of Carboniferous deposits in western Libya: Recording the sedimentary response of the northern Gondwana margin to climate and sea-level changes (United States)

    Fröhlich, Sebastian; Petitpierre, Laurent; Redfern, Jonathan; Grech, Paul; Bodin, Stéphane; Lang, Simon


    Assedjefar Formation exibits a gradual decrease in coarse clastic sediment supply throughout the Serpukhovian and by the Bashkirian and Moscovian during the deposition of the Dembaba Formation a carbonate depositional system was established. Limestones are dominantly made up of a heterozoan fauna (brachiopods, crinoids, bryozoans, gastropods) and are mostly preserved as shallow marine storm and coastal deposits. It is hypothesised that a local increase in aridity and/or the gradual erosion and decreasing topography of the hinterland mountains, with the resulting reduction in discharge, controlled this shift from clastic to carbonate deposition. Available data indicate that the Murzuq Basin was interconnected with the Ghadames Basin at this time and is a postdepositional basin with respect to the Carboniferous interval. The sedimentological and sequence stratigraphic data from the present study offer new insights into the depositional setting and facies distribution in the Carboniferous, and the recognition of major incised fluvial systems has significant implications in the search for potential Carboniferous hydrocarbon reservoirs in the Murzuq, Ghadames, and Illizi Basins.

  7. Fingerprinting of glacial silt in lake sediments yields continuous records of alpine glaciation (35–15 ka), western USA (United States)

    Rosenbaum, Joseph G.; Reynolds, Richard L.; Colman, Steven M.


    Fingerprinting glacial silt in last glacial-age sediments from Upper Klamath Lake (UKL) and Bear Lake (BL) provides continuous radiocarbon-dated records of glaciation for the southeastern Cascade Range and northwestern Uinta Mountains, respectively. Comparing of these records to cosmogenic exposure ages from moraines suggests that variations in glacial flour largely reflect glacial extent. The two areas are at similar latitudes and yield similar records of glacial growth and recession, even though UKL lies less than 200 km from the ocean and BL is in the continental interior. As sea level began to fall prior to the global Last Glacial Maximum (LGM), existing glaciers in the UKL area expanded. Near the beginning of the global LGM (26.5 ka), the BL record indicates onset of glaciation and UKL-area glaciers underwent further expansion. Both records indicate that local glaciers reached their maximum extents near the end of the global LGM, remained near their maxima for ~1000 yr, and underwent two stages of retreat separated by a short period of expansion.

  8. Tropical Ice Core Records: Evidence for Asynchronous Glaciation on Milankovitch Time Scales (United States)

    Thompson, L. G.


    Ice core records are available from selected high altitude, low and mid-latitude ice caps. Comparisons are made among the histories from the Tibetan Plateau, the tropical Andes of South America, and Kilimanjaro in East Africa. Three of these records (Guliya in China, Huascarán in Peru, and Sajama in Bolivia) contain ice deposited during the Last Glacial Stage (LGS). The oxygen isotopic ratios (δ 18O) of this ice suggest significant tropical cooling ( ~5° C). Comparison of a global array of cores reveals large-scale similarities as well as important regional differences. The δ 18O shift from Early Holocene to LGM is 5.4‰ on Sajama, 6.3‰ on Huascarán, ~5.3‰ in central Greenland, 6.6‰ at Byrd Station in Antarctica and 5.4‰ at Vostok also in Antarctica. These records all show similar isotopic depletion, reflecting significant global cooling at the Late Glacial Maximum (LGM). As continental ice sheets form only in high latitudes (>40° ), those regions have provided most of the evidence for the pulsing of Quaternary glaciations. In low latitudes, glaciers are restricted to the high mountains and only recently have enough long tropical ice core histories become available to investigate the timing of glaciations there. Long ice cores recovered to bedrock at 7 high-altitude (>5300 m) sites on three continents are investigated for synchroneity of their glaciation histories. The cores from Huascarán in Peru at 9° S and Sajama in Bolivia at 18° S contain continuous records back into the LGS. Both glaciers clearly survived the early Holocene warm period (9 to 6 ka B.P.), but neither contains a long record of glacial stage climate back to the previous interglacial. Rather, the published records from Huascarán and Sajama extend back ~19 kyr and 25 kyr, respectively. Hence, both mountaintops, among the highest in South America, appear to have been ice free during a time considered significantly colder than the Holocene. The records from Dasuopu (28° N) and

  9. Cirque-driven erosion of the Scandinavian mountains (United States)

    Jansen, John D.; Codilean, Alexandru T.; Egholm, David L.; Knudsen, Mads F.; Korup, Oliver; Stroeven, Arjen; Goodfellow, Bradley; Andersen, Jane L.; Ugelvig, Sofie V.; Klein, Josefin


    Climatic versus tectonic explanations for Scandinavian topography have sustained a century-long dispute. Here, at high-latitudes, the more recent question of whether Late-Cenozoic cooling has influenced mountain erosion rates is especially apt because glaciations commenced earlier: >10 Myr and possibly ~34 Myr according to marine palaeorecords. Although selective glacial incision along valley troughs is well recognised in Scandinavia, the legacy of glacial cirque erosion has yet to be fully investigated. We examine the topographic legacy of mountain glaciation in seven massifs of the Caledonian Scandes (western Scandinavia ~61-70° N): Lyngen, Kebnekaise, Sarek, Saltfjellet, Dovrefjell, Jostedalsbreen, and Jotunheimen. Glacial cirques are the product of discrete alpine glaciers and so the elevation of ice-free cirques provides a guide to past fluctuations in regional equilibrium line altitude (ELA). The Scandes currently hosts >3400 mountain glaciers and the distribution of >10,000 ice-free cirques indicates that glaciers have extended much lower and farther in the past. Previous workers argue that alpine glaciations focus erosion selectively at and above a zone of cirques, which approximates the long-term average 'palaeo-ELA'. First, we set out to examine the topographic relationships between mountain peak elevation, ELA, cirque-floor elevations, and the distribution of low-slope (cirques were mapped and plotted relative to the ELA surfaces. For all seven massifs, cirque-floors cluster within a discrete elevational range: 240-490 m (25-75th percentiles) below ELA, suggesting a well-defined 'palaeo-ELA'. Hypsometric analyses show that this 'palaeo-ELA' closely matches the maximum frequency of low-slope terrain. Consistent with studies elsewhere, terrain surface area declines exponentially above modern ELA (4-13% in total) and peaks protrude cirque floors, and mountain peaks; namely, the erosional processes involved in generating a cold-climate topographic signature

  10. A process-based hierarchical framework for monitoring glaciated alpine headwaters (United States)

    Weekes, Anne A.; Torgersen, Christian E.; Montgomery, David R.; Woodward, Andrea; Bolton, Susan M.


    Recent studies have demonstrated the geomorphic complexity and wide range of hydrologic regimes found in alpine headwater channels that provide complex habitats for aquatic taxa. These geohydrologic elements are fundamental to better understand patterns in species assemblages and indicator taxa and are necessary to aquatic monitoring protocols that aim to track changes in physical conditions. Complex physical variables shape many biological and ecological traits, including life history strategies, but these mechanisms can only be understood if critical physical variables are adequately represented within the sampling framework. To better align sampling design protocols with current geohydrologic knowledge, we present a conceptual framework that incorporates regional-scale conditions, basin-scale longitudinal profiles, valley-scale glacial macroform structure, valley segment-scale (i.e., colluvial, alluvial, and bedrock), and reach-scale channel types. At the valley segment- and reach-scales, these hierarchical levels are associated with differences in streamflow and sediment regime, water source contribution and water temperature. Examples of linked physical-ecological hypotheses placed in a landscape context and a case study using the proposed framework are presented to demonstrate the usefulness of this approach for monitoring complex temporal and spatial patterns and processes in glaciated basins. This approach is meant to aid in comparisons between mountain regions on a global scale and to improve management of potentially endangered alpine species affected by climate change and other stressors.

  11. Late Quaternary glaciation history of Isla de los Estados, southeasternmost South America (United States)

    Möller, Per; Hjort, Christian; Björck, Svante; Rabassa, Jorge; Ponce, Juan Federico


    Isla de los Estados is a mountainous island southeast of Tierra del Fuego, in southernmost South America. Its central and eastern parts have an alpine topography, transected by U-shaped valleys, small, partly over-deepened fjords, and a multitude of abandoned cirques, all associated with extensive former local glaciations. Traces of glacial erosion generally reach 400-450 m a.s.l., and above that trimline a distinct sharp-edged nunatak derived landscape is present. The westernmost part of the island has a lower, more subdued topography, reflecting its "softer" geology but possibly also over-running and erosion by mainland-derived ice streams. The present study concentrated on glacigenic sediment sequences exposed along coastal erosional cliffs. A combination of OSL and 14C datings show that these sediments mostly date from the latest (Wisconsinan/Weichselian) glacial cycle, i.e. from the last ca. 100 ka with the oldest (glaciolacustrine) deposits possibly as old as 90-80 ka. The upper parts of overlying tills, with associated lateral and terminal moraines from glaciers that expanded onto an eustatically exposed dry shelf north of the island, date from the last global glacial maximum (LGM). Radiocarbon ages of peat and lake sediments indicate that deglaciation began 17-16 cal ka BP.

  12. Glaciation and erosion of Eastern Greenland at the Eocene-Oligocene transition: Insights from low-temperature thermochronology (United States)

    Bernard, Thomas; Steer, Philippe; Gallagher, Kerry; Szulc, Adam; Whittam, Andrew


    Climate cooling through the Late Cenozoic was important in the evolution of glaciated mountain ranges. While the onset of accelerated Cenozoic exhumation is generally associated with the Quaternary at mid-latitudes, coincident with the local onset of glaciation, some high-latitude passive margins may have experienced earlier glaciation starting at 30-38 Ma or even 45 Ma. To address this issue, we use a set of new AFT data from 16 sub-vertical profiles sampled along the fjords of the central Eastern Greenland margin between 68° and 76° N, combined with new apatite (U-Th-Sm)/He (AHe) data from selected profiles. To infer thermal histories and exhumation from these profiles, we use the software QTQt. The modeling results show a major phase of exhumation in the East Greenland margin between 68° and 76° N starting at 30±5 Ma. The spatial distribution of the exhumation shows that normal faulting on East Greenland margin had no resolvable influence on exhumation related to the cooling phase. However, the timing is coincident with the dramatic worldwide fall of surface temperature at the Eocene-Oligocene transition. We therefore suggest that a transition from an Eocene fluvial to an Oligocene glacial-dominated landscape triggered a period of enhanced erosion. We infer from the thermal histories that around 2.7±1.9 km of erosion occurred close to the coast since the Eocene-Oligocene transition. This amount of erosion is consistent with the incision of the fjords and with the effective removal of 2.3±1.5 km of basalt thickness, deduced by the thermal modeling of a heating phase at 55±5 Ma. This phase of erosion is most strongly evidenced near the coast, suggesting either that continental ice extent was limited to the coastal areas or that erosion was less efficient outside these areas, leading to no obvious signal in thermochronometric data further north. Overall, this study provides the first onshore evidence of the onset of continental ice in East Greenland margin


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    Full Text Available A new and well-preserved fossil whip scorpion (Arachnida: Uropygi: Thelyphonida is described from the Late Carboniferous of the Carnic Alps, Friuli, Italy. It is referred to Parageralinura marsiglioi n. sp. The new specimen is the first Carboniferous arachnid to be described from mainland Italy and is possibly the youngest Palaeozoic thelyphonid.

  14. The geomorphology of a glaciated continental shelf, Western Scotland, UK (United States)

    Howe, John; Dove, Dayton; Bradwell, Tom


    We present recently collected swath bathymetry and legacy seismic data from two regions of the north-west UK continental shelf: the Sea of the Hebrides; and the Firth of Lorn, western Scotland. Both regions have experienced extensive Pleistocene ice sheet glaciation and both provide abundant geomorphological evidence of subglacial and postglacial processes. The Sea of the Hebrides bathymetry data cover 2200 km2 and provide new geomorphological evidence for an ice stream flowing from western Scotland and the Inner Hebrides focusing towards a trough-mouth fan (the Barra Fan) at the continental shelf break during the height of the last glaciation. Notably, bedrock structures provide a control on the location and orientation of glacially overdeepened basins and troughs on the inner shelf. Whilst around the Islands of Canna and Rum, convergent seabed glacial lineations and other subglacially streamlined features eroded in bedrock preserve the direction of ice sheet movement - indicating ice streaming in a south-westerly direction across the continental shelf. We propose that this fast-flow zone formed part of a larger convergent ice stream system draining much of western Scotland and the north of Ireland. The Firth of Lorn bathymetry acquisition comprises 553km2 of data, collected as part of the INIS Hydro program (Ireland, Northern Ireland and Scotland Hydrographic Survey). This region of nearshore continental shelf is revealed as predominantly bedrock-dominated seabed, characterised by a series of narrow, strongly fault-controlled troughs, part of the Great Glen Fault Zone complex. Evidence for glaciation is widespread and well preserved in the Firth of Lorn and surrounding seabed with moraines, bedrock lineations (?megagrooves?) and overdeepened basins common across the area. Initial mapping shows that our understanding of the configuration and style of deglaciation in these sectors of the former British-Irish Ice Sheet can be greatly improved by the collection of


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    Svitlana Dovbenko


    Full Text Available Schools in the Ukrainian Carpathian mountain region work in specific conditions. They have original traditions, a special nature of learning and work. Indeed, because of a remote location mountain village school becomes the center for a cultural and spiritual life. Of course, it is related to a present social and economic situation in the country and a slow progress of society. Therefore, we need to look at mountain school with a broader angle, help it in comprehensive development of an individual and ensure an availability of quality education for children living in mountainous areas. Here we should talk about learning as well as laying the foundations for a life success. The international research project Mountain School. Status. Problems. Prospects for Development. Is established to help solve these problems. Precarpathian National University is an active member of the project.

  16. Petrogenesis and tectonic implications of the Early Carboniferous to the Late Permian Barleik plutons in the West Junggar (NW China) (United States)

    Liu, Bo; Han, Bao-Fu; Ren, Rong; Chen, Jia-Fu; Wang, Zeng-Zhen; Zheng, Bo


    The Paleozoic accretionary orogenesis and continental crustal growth in Central Asia are thought to have close relationship with the evolution of the Paleo-Asian Ocean (PAO). The well-exposed plutons in the northern Barleik Mountains of the West Junggar region, NW China, may provide essential insights into the evolution of the Junggar Ocean, a branch of the PAO, and mechanism of continental crustal growth. Our work on the Barleik plutons indicates an early suite of 324-320 Ma diorite and a late suite of 314-259 Ma quartz syenite and granitic porphyry. All the plutons are characterized by high-K calc-alkaline to shoshonitic signatures, varying depletion in Nb, Ta, Sr, P, Eu, and Ti, low initial 87Sr/86Sr ratios (0.70241-0.70585), strongly positive εNd(t) values (+ 5.7-+7.7), and young one-stage Nd model ages (390-761 Ma), suggesting that they resulted from different batches of magma that were produced by fractional crystallization of a metasomatized mantle source with minor crustal contamination. The diorite is coeval with the youngest arc magmatic rocks, indicating a subduction-related origin. By contrast, the quartz syenite and granitic porphyry are geochemically similar to A2-type granites, with high Zr, Ga, and FeOT/[FeOT + MgO], and are coeval with the widespread plutons in the West Junggar. This, together with the occurrence of Late Carboniferous fluvial deposits and the lack of < 320 Ma ophiolitic and subduction-related metamorphic lithologies, definitively indicates a post-collisional setting after the closure of the Junggar Ocean. Slab breakoff accompanied by asthenospheric upwelling and basaltic underplating is a possible geodynamic process that is responsible for the post-collisional magmatism and vertical crustal growth in the region. Thus a tectonic switch from subduction to post-collision started at the end of the Early Carboniferous ( 320 Ma), probably as a result of the final closure of the Junggar Ocean.

  17. Time scale bias in erosion rates of glaciated landscapes. (United States)

    Ganti, Vamsi; von Hagke, Christoph; Scherler, Dirk; Lamb, Michael P; Fischer, Woodward W; Avouac, Jean-Philippe


    Deciphering erosion rates over geologic time is fundamental for understanding the interplay between climate, tectonic, and erosional processes. Existing techniques integrate erosion over different time scales, and direct comparison of such rates is routinely done in earth science. On the basis of a global compilation, we show that erosion rate estimates in glaciated landscapes may be affected by a systematic averaging bias that produces higher estimated erosion rates toward the present, which do not reflect straightforward changes in erosion rates through time. This trend can result from a heavy-tailed distribution of erosional hiatuses (that is, time periods where no or relatively slow erosion occurs). We argue that such a distribution can result from the intermittency of erosional processes in glaciated landscapes that are tightly coupled to climate variability from decadal to millennial time scales. In contrast, we find no evidence for a time scale bias in spatially averaged erosion rates of landscapes dominated by river incision. We discuss the implications of our findings in the context of the proposed coupling between climate and tectonics, and interpreting erosion rate estimates with different averaging time scales through geologic time.

  18. Mountaineering Tourism

    Directory of Open Access Journals (Sweden)

    Patrick Maher


    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.

  19. 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.


    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 Permo-Ca

  20. The Permo-Carboniferous genus Sagenodus and the beginning of modern lungfish

    NARCIS (Netherlands)

    Schultze, H.-P.; Chorn, J.


    were present in North America ( The lungfish Sagenodus is a widespread Permo-Carboniferous genus found in Europe and North America. Important localities in the U.S.A. include Middle Pennsylvanian coals near Linton, Ohio, Upper Pennsylvanian deposits near Robinson and Hamilton, Kansas, and Peoria, Il

  1. A new carboniferous species of isogramma (dyctionellida, brachiopoda from NW Serbia

    Directory of Open Access Journals (Sweden)

    Stojanović-Kuzenko Smiljana


    Full Text Available Representatives of a new Early Moscovian, Carboniferous, species of the dictionelid brachiopod Isogramma MEEK & WORTHEN, 1870 from northwestern Serbia are described. Small dimensions, weakly developed dorsal lateral ridges and the absence of dorsal anterior sulcus characterize this new taxon. A comparison with other representatives of genus Isogramma and some remarks of this genus are given.

  2. The Permo-Carboniferous genus Sagenodus and the beginning of modern lungfish

    NARCIS (Netherlands)

    Schultze, H.-P.; Chorn, J.


    were present in North America ( The lungfish Sagenodus is a widespread Permo-Carboniferous genus found in Europe and North America. Important localities in the U.S.A. include Middle Pennsylvanian coals near Linton, Ohio, Upper Pennsylvanian deposits near Robinson and Hamilton, Kansas, and Peoria,

  3. Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets basin, Ukraine)

    NARCIS (Netherlands)

    Van Hinsbergen, Douwe J J; Abels, Hemmo A.; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; Van Der Meer, Douwe G.; Geluk, Mark; Stephenson, Randell A.


    The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of

  4. 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.


    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, B

  5. The alluvial architecture of the Coevorden Field (Upper Carboniferous), the Netherlands

    NARCIS (Netherlands)

    Kombrink, H.; Bridge, J.S.; Stouthamer, E.


    A detailed reconstruction of the alluvial architecture of the Coevorden gas Field (Tubbergen Formation, Upper Carboniferous), which is located in the northeastern part of the Netherlands, is presented. This reconstruction is based on well logs, cross-sections and paleogeographic maps. Sedimentolog

  6. Maturity of carboniferous source rocks in Central Onshore Netherlands. the impact of the Permian thermal anomaly

    NARCIS (Netherlands)

    Abdul Fattah, R.; Verweij, J.M.


    Pre-Westphalian layers are considered as potential source rocks in the Netherlands. However, there is little amount of information available on their maturity. 3D basin modelling is carried out on Central Onshore Netherlands to investigate the maturity of the deep Carboniferous source rocks. A detai

  7. Molecular characterization of flash pyrolysates of two Carboniferous coals and their constituting maceral fractions

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Hartgers, W.A.; Ling, Y.; Leeuw, J.W. de; Dyrckacz, G.


    Two high-volatile bituminous Upper Carboniferous coals from the Argonne Premium Coal Set and their constituting liptinite, vitrinite, and inertinite fractions, obtained by density gradient centrifugation (DGC), were characterized by Curie point pyrolysis-gas chromatography-mass spectrometry. A

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

    NARCIS (Netherlands)

    Bless, M.J.M.


    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 b

  9. Maturity of carboniferous source rocks in Central Onshore Netherlands. the impact of the Permian thermal anomaly

    NARCIS (Netherlands)

    Abdul Fattah, R.; Verweij, J.M.


    Pre-Westphalian layers are considered as potential source rocks in the Netherlands. However, there is little amount of information available on their maturity. 3D basin modelling is carried out on Central Onshore Netherlands to investigate the maturity of the deep Carboniferous source rocks. A

  10. A micropalaeontological and palynological insight into Early Carboniferous floodplain environments (United States)

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


    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

  11. Carboniferous granites on the northern margin of Gondwana, Anatolide-Tauride Block, Turkey - Evidence for southward subduction of Paleotethys (United States)

    Candan, O.; Akal, C.; Koralay, O. E.; Okay, A. I.; Oberhänsli, R.; Prelević, D.; Mertz-Kraus, R.


    Carboniferous metagranites with U-Pb zircon crystallization ages of 331-315 Ma crop out in the Afyon zone in the northern margin of the Anatolide-Tauride Block, which is commonly regarded as part of Gondwana during the Late Palaeozoic. They are peraluminous, calc-alkaline and are characterized by increase in Rb and Ba, decrease in Nb-Ta, and enrichment in Sr and high LILE/HFSE ratios compatible with a continental arc setting. The metagranites intrude a metasedimentary sequence of phyllite, metaquartzite and marble; both the Carboniferous metagranites and metasedimentary rocks are overlain unconformably by Lower Triassic metaconglomerates, metavolcanics and Upper Triassic to Cretaceous recrystallized limestones. The low-grade metamorphism and deformation occurred at the Cretaceous-Tertiary boundary. There is no evidence for Carboniferous deformation and metamorphism in the region. Carboniferous arc-type granites and previously described Carboniferous subduction-accretion complexes on the northern margin of the Anatolide-Tauride Block suggest southward subduction of Paleotethys under Gondwana during the Carboniferous. Considering the Variscan-related arc granites in Pelagonian and Sakarya zones on the active southern margin of Laurasia, a dual subduction of Paleotethys can be envisaged between Early Carboniferous and Late Permian. However, the southward subduction was short-lived and by the Late Permian the Gondwana margin became passive.

  12. Permo-Carboniferous Sequence Stratigraphy and Sea Level Changes in North China Platform

    Institute of Scientific and Technical Information of China (English)


    Through a sequence stratigraphic research on the Permo-Carboniferous in North China, it is suggested that the boundary of the Carboniferous and the Permian may be better moved down to the bottom of the main workable coalbed which is overlain by the limestones containing Pseudoschwagerina zone. This study mainly deals with the Upper Carboniferous, the Lower Permian and the lower part of the Middle Permian coal-bearing strata, which are 150-180 m thick totally and can be divided into 2 mesosequences, including 6 sequence sets and 19 sequences. The lithostratigraphic units are diachronous in North China. The upper two limestones of the Taiyuan Formation in the central part of the study area may be correlated with the bottom two limestones of the lower Taiyuan Formation in the southern part. The Shanxi Formation in the central and northern parts may be correlated with most of the Taiyuan Formation in the southern part. The Xiashihezi Formation in the northern part may be correlated with the upper part of Shanxi Formation in the central and southern parts. The Shangshihezi Formation in the northern part may be correlated with the Xiashihezi Formation in the southern part. The paleogeographical maps are compiled in a chrono-stratigraphic framework. From the Late Carboniferous to the Early Permian, 3 cycles of sea level change and transgression-regression occurred, and the major transgression took place in the Asselian. In the Late Carboniferous, the direction of transgression was from the east to the west, and in the Early Permian it was from the southeast and the southwest to the north. Three workable coalbed groups were formed in Asselian, early Sakmarian and late Sakmarian respectively. The TST coals developed under the bottom of the Asselian limestones are the best coals for coalbed meathane extracting. The Sakmarian coal beds were formed in HST. The coal beds of Lower Permian distribute southward along with the relative sea level falls and sediment progradation.

  13. The character of the glaciated Mid-Norwegian continental margin (United States)

    Oline Hjelstuen, Berit; Haflidason, Haflidi; Petter Sejrup, Hans


    During Pleistocene the development of the NW European continental margin was strongly controlled by the variability in ocean circulation, glaciations and sea-level changes. Repeated occurrence of shelf edge glaciations, from Ireland to Svalbard, started at Marine Isotope Stage 12 (c. 0.5 Ma). During these periods, fast moving ice streams also crossed the Mid-Norwegian continental shelf on a number of locations, and a thick prograding wedge accumulated on the continental slope. During shelf edge glaciations and in early deglaciation phases high sedimentation rates (>2000 cm/ka) existed, and glacigenic debris flows and melt water plumes were deposited. Within these depositional environments we identify three slide events. These slides have affected an area between 2900 and 12000 km2 and involved 580-2400 km3 of sediments, noting that the slide debrites left by the failure events reach a maximum thickness of c. 150 m. The failures have occurred within an area dominated by gradients less than 1 degree, and observation of long run-out distances indicate that hydroplaning was important during slide development. Gas hydrate bearing sediments are identified on the mid-Norwegian continental margin, but appears to be absent in the slide scars. Thus, dissociation of gas hydrates may have promoted conditions for the failures to occur. Within the region of gas hydrate bearing Pleistocene sediments the Nyegga Pockmark Field is observed. This field contains more than 200 pockmarks and is located at a water depth of 600-800 m. The pockmarks identified are up to 15 m deep, between 30 m and 600 m across and reach a maximum area of c. 315 000 m2. The pockmarks are sediment-empty features and are restricted to a <16.2 cal ka BP old sandy mud unit. It seems that the Nyegga Pockmark Field does not show any strong relationship neither to seabed features, sub-seabed structures nor the glacial sedimentary setting. Thus, this implies a more complex development history for the Nyegga

  14. A simple model for 100 K-year oscillations in glaciation (United States)

    Lindzen, R. S.


    A simple climatic model which produces glaciation cycles of 100 K periods in response to forcing by 20 K, 40 K, and 100 K periods is described. The model is based on Milankovitch's (1930) hypothesis that glaciation fluctuations are forced by orbital variation and the associated change in insolation. The sea ice/snow cover line for the model, and the relation between heat variations and the ice/snow line are analyzed. The sea ice/snow cover line for the model is between the pole and 53 deg latitude and the line's position is the forcing for the glaciation cycle. Examples of the model's response to forcing are presented and evaluated. The negative glaciation permitted by the model is studied. The role of CO2 feedback in the glaciation cycle is investigated.

  15. Map Showing Limits of Tahoe Glaciation in Sequoia and Kings Canyon National Parks, California (United States)

    Moore, James Gregory; Mack, Gregory S.


    The latest periods of extensive ice cover in the Sierra Nevada include the Tahoe glaciation followed by the Tioga glaciation, and evidence for these ice ages is widespread in the Sequoia and Kings Canyon National Parks area. However, the timing of the advances and retreats of the glaciers during the periods of glaciation continues to be a matter of debate. A compilation of existing work (Clark and others, 2003) defines the Tioga glaciation at 14-25 thousand years ago and splits the Tahoe glaciation into two stages that range from 42-50 and 140-200 thousand years ago. The extent of the Tahoe ice mass shown in the map area is considered to represent the younger Tahoe stage, 42-50 thousand years ago. Evidence of glaciations older than the Tahoe is limited in the southern Sierra Nevada. After the Tioga glaciation, only minor events with considerably less ice cover occurred. The Tioga glaciation was slightly less extensive than the Tahoe glaciation, and each covered about half of the area of Sequoia and Kings Canyon National Parks. The Tahoe glaciers extended 500-1,000 ft lower and 0.5-1.2 mi farther down valleys. Evidence for the Tahoe glacial limits is not as robust as that for Tioga, but the extent of the Tahoe ice is mapped because it covered a larger area and the ice did leave prominent moraines (piles of sediment and boulders deposited by glaciers as they melted at their margins) lower on the east front of the range. Current Sierra redwood (Sequoiadendron giganteum) groves occur in a belt on the west side of the Sierra Nevada, generally west of the area of Tahoe glaciation.

  16. 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.


    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 Lan

  17. Conodont zonation and the Devonian/Carboniferous (Famennian/Tournaisian) boundary in the Naltaş section, eastern Taurides, Turkey (United States)

    Atakul-Özdemir, Ayşe


    Conodont faunas from the Devonian/Carboniferous Naltaş section (eastern Taurides, Turkey) are presented. The faunas include important marker species of the latest Devonian earliest Carboniferous interval, belonging to the genera Siphonodella, Bispathodus, Polygnathus, Pseudopolygnathus, Apatognathus and Branmehla. Four conodont zones, comparable to the standard conodont zonation, are established in the studied succession, from the oldest to the youngest: (1) Bispathodus ultimus, (2) Siphonodella praesulcata Zones (Upper Famennian), (3) Siphonodella sulcata and (4) Siphonodella bransoni Zones (Lower Tournaisian). The Devonian/Carboniferous boundary in the eastern Taurides is recognized by the first appearance of Siphonodella sulcata.

  18. Seasonal changes in Fe along a glaciated Greenlandic fjord. (United States)

    Hopwood, Mark; Connelly, Douglas; Arendt, Kristine; Juul-Pedersen, Thomas; Stinchcombe, Mark; Meire, Lorenz; Esposito, Mario; Krishna, Ram


    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 (removing Fe from surface waters before it can be exported to coastal seas.

  19. Wet-based glaciation in Phlegra Montes, Mars. (United States)

    Gallagher, Colman; Balme, Matt


    Eskers are sinuous landforms composed of sediments deposited from meltwaters in ice-contact glacial conduits. This presentation describes the first definitive identification of eskers on Mars still physically linked with their parent system (1), a Late Amazonian-age glacier (~150 Ma) in Phlegra Montes. Previously described Amazonian-age glaciers on Mars are generally considered to have been dry based, having moved by creep in the absence of subglacial water required for sliding, but our observations indicate significant sub-glacial meltwater routing. The confinement of the Phlegra Montes glacial system to a regionally extensive graben is evidence that the esker formed due to sub-glacial melting in response to an elevated, but spatially restricted, geothermal heat flux rather than climate-induced warming. Now, however, new observations reveal the presence of many assemblages of glacial abrasion forms and associated channels that could be evidence of more widespread wet-based glaciation in Phlegra Montes, including the collapse of several distinct ice domes. This landform assemblage has not been described in other glaciated, mid-latitude regions of the martian northern hemisphere. Moreover, Phlegra Montes are flanked by lowlands displaying evidence of extensive volcanism, including contact between plains lava and piedmont glacial ice. These observations provide a rationale for investigating non-climatic forcing of glacial melting and associated landscape development on Mars, and can build on insights from Earth into the importance of geothermally-induced destabilisation of glaciers as a key amplifier of climate change. (1) Gallagher, C. and Balme, M. (2015). Eskers in a complete, wet-based glacial system in the Phlegra Montes region, Mars, Earth and Planetary Science Letters, 431, 96-109.

  20. Successful Female Mountaineers

    Institute of Scientific and Technical Information of China (English)



    The Third Mountaineering Meet took place from September 26 to October 8, 2003. It was sponsored by the Tibet Association for Mountaineers and undertaken by the Tibet Mountaineering Team and the Tibet Mountaineering School.

  1. Population genetics of the westernmost distribution of the glaciations-surviving black truffle Tuber melanosporum. (United States)

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


    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.

  2. The glacial relief in the Leaota Mountains

    Directory of Open Access Journals (Sweden)



    Full Text Available The presence of glacial relief in the Romanian medium height massifs is still controversial. The medium height mountains, such as theLeaota Mountains (in the Bucegi group, with maximum altitudes of almost 2000 m andmedium altitudes of approximately 1250 m, can display traces of glacial relief dating from theUpper Pleistocene. The aim of this article is to provide evidence about the presence of theglacial morphology in the northern part of the Leaota Peak, the main orographic node in themassif with the same name. Thus, on the basis of field observations, of topographical mapanalysis and by using the geographic information systems which made possible a detailedmorphometric analysis, I was able to gather evidence proving the existence of a glacial cirquein the Leaota Mountains. The arguments put forward in this article show that the glacial reliefis represented in the Leaota Mountains through a small-size suspended glacial cirque, whichdisplays all the morphologic elements proving the existence of glaciation in this massif.

  3. Glacial reorganization of topography in a tectonically active mountain range (United States)

    Adams, Byron; Ehlers, Todd


    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns, and not tectonic rock uplift rates. Alpine glaciers drastically altered the relief structure of the Olympic Mountains. The details of these relief changes are recorded in channel profiles as overdeepenings, reduced slopes, and associated knickpoints. We find the position of these relief changes within the orogen is dependent on the position of the Pleistocene ELA. While alpine glaciers overdeepened valleys in regions near the Pleistocene ELA (which has a tendency to increase relief), headward erosion of west and north flowing glacier systems captured significant area from opposing systems and caused drainage divide lowering. This divide lowering reduced relief throughout the range. We demonstrate similar topographic effects recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on

  4. 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 (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


    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

  5. Mountain medicin

    DEFF Research Database (Denmark)

    Bay, Bjørn; Hjuler, Kasper Fjellhaugen


    Travelling to high altitudes is an increasingly popular form of recreational holiday. Individual medical advice may be essential for certain groups of individuals such as patients with chronic disorders, pregnant women or children. This is the second part in a series of two articles on mountain...

  6. Changbai Mountains

    Institute of Scientific and Technical Information of China (English)


    The Changbai Mountains are located within the boundaries of Antu County, Fusong County and Changbai County of Jilin City of Jilin Province. They cover a total area of more than 200,000 hectares and is one of the largest nature preserves in China. There are abundant species of living things, such as Dongbei Tiger, sika, sable and

  7. Paleoecology of Late Carboniferous Phylloid Algae in Southern Guizhou,SW China

    Institute of Scientific and Technical Information of China (English)


    Phylloid algae are important reef-builders in the late Carboniferous. This paper focuses on the paleoecology of phylloid algae in the Late Carboniferous on well-exposed reefs in Ziyun County,Guizhou Province. Phylloid algae growing closely packed are attached via holdfast or similar structure to substrate. They were growing in environments such as shallow water, photic zone and below the wave base with medium energy currents. They have a variety of morphological forms, such as single cup-shaped, cabbage-shaped and clustering cup-shaped. The thalli are of certain tenacity and intensity. In the areas dominated by phylloid algae, other marine organisms are relatively scarce.Obviously, phylloid algae are stronger competitors for living space than other co-occurring organisms.

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

    Energy Technology Data Exchange (ETDEWEB)

    Caballero, F. Reyes, E-mail:; Martínez Ovalle, S. A., E-mail: [Universidad Pedagógica y Tecnológica de Colombia, Grupo de Física Nuclear Aplicada y Simulación (Colombia); Díaz Lagos, M., E-mail: [Universidad Pedagógica y Tecnológica de Colombia, Escuela de Ingeniería Geológica (Colombia); Gómez, O. P., E-mail: [Universidad Pedagógica y Tecnológica de Colombia, Escuela de Ingeniería de Minas (Colombia); Blandón, A., E-mail: [Universidad Nacional de Colombia, Departamento de Materiales y Minerales, Facultad de Minas (Colombia)


    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.

  9. Contributions of palynology to Carboniferous biostratigraphy and coal geology of the Atlantic provinces of Canada

    Energy Technology Data Exchange (ETDEWEB)

    Hacquebard, P.A. [Geological Survey of Canada, Dartmouth, NS (Canada). Atlantic Geoscience Centre


    W.A. Bell`s palaeobotanical and geological studies carried out between 1927 and 1948 resulted in the recognition of six stratigraphic units in the Carboniferous system of the Atlantic Provinces of Canada. Subsequent palynological research provided additional information on: (1) The recognition of nineteen miospore zones in the six groups of the Carboniferous succession. (2) Regional correlation of the stratigraphic units in areas where, due to lack of plant megafossils, no age relationship had been established. This resulted in recognizing the existence of the Gulf of St. Lawrence coalfield, the largest in eastern Canada. (3) Detailed coal seam correlations from miospore histograms, as an aid to structural and stratigraphic interpretations, resulted in delineating hitherto unknown coal reserves, notably in the Mabou and Pictou coalfields of Nova Scotia and in the Central Pennsylvanian Basin of New Brunswick. (4) The miospore assemblages provided information on the negotiation of the ancient peat mires that are valuable to coal-facies interpretations.

  10. Devonian-Carboniferous unconformity in Argentina and its relation to the Eo-Hercynian orogeny in southern South America (United States)

    López-Gamundí, O. R.; Rossello, E. A.


    The Devonian-Carboniferous contact in southern South America, characterized by a sharp unconformity, has been related to the Late Devonian-Early Carboniferous Eo-Hercynian orogeny. The Calingasta-Uspallata basin of western Argentina and the Sauce-Grande basin (Ventana Foldbelt) of eastern Argentina have been selected to characterize this unconformity. The Eo-Hercynian movements were accompanied in western Argentina by igneous activity related to a Late Devonian—Early Carboniferous magmatic arc mainly exposed today along the Andean Cordillera. This magmatic activity is partly reflected also in eastern Argentina (Ventana Foldbelt), where isotopic dates suggest a thermal event also related to the intrusions present to the west in the North Patagonian Massif and Sierras Pampeanas. The scarcity of Lower Carboniferous deposits in the stratigraphic record of southern South America suggests that the Early Carboniferous was a time interval dominated by uplift and erosion followed by widespread subsidence during the Middle and Late Carboniferous. The origin of the Eo-Hercynian orogeny can be linked with the convergence between the Arequipa Massif, and its southern extension, and the South American continent. Its effects are best represented along the ‘Palaeo-Pacific’ margin, although distant effects are discernible in the cratonic areas of eastern South America.

  11. Tyloses and Ecophysiology of the Early Carboniferous Progymnosperm Tree Protopitys buchiana


    SCHECKLER, STEPHEN E.; Galtier, Jean


    Trunk woods of Early Carboniferous Protopitys buchiana show the earliest example of tylose formation and the first record for a progymnosperm. Protopitys tyloses are more densely located in inner trunk woods and near growth layer boundaries. We suggest, therefore, that an altered physiological state of living ray cells, during dormancy and/or following water stress, was necessary to make the woods vulnerable to tylose formation. Coupled with the distribution and proximity of abundant wood ...

  12. Zircon age and heavy mineral constraints on provenance of North Sea Carboniferous sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Morton, A.C. [HM Research Associates, Woodhouse Eaves (United Kingdom); University of Aberdeen (United Kingdom). Dept. of Geology and Petroleum Geology; Hallsworth, C.R. [HM Research Associates, Woodhouse Eaves (United Kingdom); Claoue-Long, J.C. [Australian Geological Survey Organisation, Canberra (Australia)


    The understanding of sediment provenance and sediment transport routes is a key element in establishing reservoir presence in clastic petroleum systems. Determination of sediment provenance is particularly difficult in structurally complex areas and in sequences that have undergone extensive burial diagenesis. This paper describes a method that overcomes these problems, by combining quantitative heavy mineral analysis with detrital zircon age dating. Quantitative heavy mineral analysis identifies differences in sediment provenance within the sample set, and zircon age data provide diagnostic criteria for the identification of the various source terrains. The high degree of resolution shown by this approach is demonstrated using the North Sea Carboniferous as an example. The Carboniferous of the North Sea has suffered extensive diagenetic modification during its complex burial history, is difficult to image with seismic data, and in some areas, notably the central and northern North Sea, preservation is patchy. The understanding of Carboniferous sand provenance is therefore rudimentary. The Tayport and Firth Coal formations (latest Devonian to Early Carboniferous) of the Outer Moray Firth (central North Sea) were derived from a source area to the north of the British Isles, with sediment transported along the proto-Viking Graben. Some local input is recognised in the Firth Coal Formation. The Westoe Coal Formation (Westphalian B) in the southern North Sea was derived from the southeast, probably from the Saxo-Thuringian Zone of the central European Variscides. The Lower Ketch Member (Westphalian C) in the southern North Sea has a northern provenance, with abundant chrome spinel suggesting derivation from ophiolitic material on the Rinkoebing-Fyn High. (author)


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    Full Text Available A trigonotarbid arachnid from the Upper Carboniferous (Westphalian D of San Giorgio Basin, Sardinia, is described and referred to Anthracomartus voelkelianus Karsch, 1882, the type genus of the family Anthracomartidae. The occurrence extends the range of this arachnid order outside of the major Euramerican coal basins and into the western Mediterranean region. This is the first pre-Miocene arachnid from Italy to be described. 

  14. Impact of a Permo-Carboniferous high O2 event on the terrestrial carbon cycle


    Beerling, D. J.; Berner, R. A.


    Independent models predicting the Phanerozoic (past 600 million years) history of atmospheric O2 partial pressure (pO2) indicate a marked rise to approximately 35% in the Permo-Carboniferous, around 300 million years before present, with the strong potential for altering the biogeochemical cycling of carbon by terrestrial ecosystems. This potential, however, would have been modified by the prevailing atmospheric pCO2 value. Herein, we use a process-based terres...

  15. Smart engineering in the mid-carboniferous: how well could palaeozoic dragonflies Fly? (United States)

    Wootton; Kukalova-Peck; Newman; Muzon


    The wings of archaic Odonatoidea from the mid-Carboniferous of Argentina show features analogous to "smart" mechanisms in modern dragonflies that are associated with the agile, versatile flight necessary to catch prey in flight. These mechanisms act automatically in flight to depress the trailing edge and to facilitate wing twisting, in response to aerodynamic loading. The presence of similar features suggests that the earliest known odonatoids were already becoming adapted for high-performance flight in association with a predatory habit.

  16. The influence of diagenesis on the reservoir quality of Cambrian and Carboniferous sandstones, southwest Sinai, Egypt (United States)

    McBride, Earle F.; Abdel-Wahab, Antar; Salem, Alaa M. K.


    The diagenetic influence on hydrocarbon reservoir quality was investigated for the Cambrian and Lower Carboniferous sandstones of southwestern Sinai. These quartzose and feldspathic Palaeozoic sandstones were not buried more than 1 to 1.5 km until Late Cretaceous and more recent times, when the most deeply buried rocks may have reached 25 km. Porosity was reduced by compaction from an assumed original 45% to about 26%. In general, both Cambrian and Carboniferous sandstones lost more porosity by compaction (average of 19% for each) than by cementation (average of 17% and 13%, respectively). There is no significant difference in the degree of compaction shown by Cambrian (older, deeper buried) rather than Carboniferous sandstones. Cementation by iron oxide, quartz, calcite and kaolinite reduced porosity to 12-15%, except in silcretes and some ferricretes where porosity was reduced to <5%. Significant secondary porosity was created (5.8 and 5.1 % for Cambrian and Carboniferous sandstones, respectively ) chiefly by dissolution of feldspar. Kaolinite (maximum of 20%) is the most deleterious cement because it has high microporosity, which causes high residual water saturation, and occurs as tiny crystals that have the potential to break loose during rapid fluid flow and block the pore throats. The present-day porosity in these sandstones averages 19% and ranges from 1.5 to 32%. Many sandstone samples (47% of a total of 178 samples) have permeability values higher than 1000 md. The plot of porosity versus the log of permeability has a good correlation indicating that microporosity, even though locally important, does not significantly influence reservoir quality. In spite of their age and the large volumes of groundwater that probably passed through them, these Palaeozoic sandstones retain sufficient porosity and permeability to possess excellent reservoir quality.

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.


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    Full Text Available Four foraminiferal paleobiogeographic realms are distinguished in the Carboniferous – North Paleotethyan, Perigondwanian, Siberian and North American. The Carboniferous foraminiferal faunas of both the Istanbul and Anatolide-Tauride zones distinctly differ from both Cimmerian terranes (Central Afghanistan, Qiangtang and Libya and Egypt of the Perigondwana Realm and show close relation to the North Paleotethyan Realm, especially to the Fennosarmatian Province of southeastern Laurussia (Moesian and Scythian platforms or to the Central Asiatic Province. A model that best fits with available evidence is that the Anatolide-Tauride Zone was either a part or located close to Laurasia in Carboniferous. The Istanbul Zone represents an equivalent of the Rhenohercynian Zone of the Central Europe and can not be compared with Intra-Alpine or south Variscan terranes which may be correlated with the Anatolide-Tauride Zone. Later, in the Permian, the Anatolide -Tauride Zone may has been separated from the Eurasian mainland by the Karakaya back-arc ocean. 

  19. Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets basin, Ukraine) (United States)

    van Hinsbergen, Douwe J. J.; Abels, Hemmo A.; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; van der Meer, Douwe G.; Geluk, Mark; Stephenson, Randell A.


    The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of the basin's stratigraphy. Here, we provide detailed sedimentological data from 13 sections that cover 1.5 of the total of 5 km of the Bashkirian and Moscovian stages and assess the paleoenvironment and paleo-current directions. Middle Carboniferous deposition occurred in a shelf environment, with coal deposition, subordinate fluvial facies, and abundant lower and middle shoreface facies, comprising an intercalated package of potential source and reservoir rocks. Sedimentary facies indicate a paleodepth range from below storm wave base to near-coastal swamp environments. Sedimentation and subsidence were hence in pace, with subtle facies changes likely representing relative sea-level changes. Paleocurrent directions are remarkably consistently southeastward in time and space in the different sedimentary facies across the Donbas Fold Belt, illustrating a dominant sedimentary infill along the basin axis, with little basin margin influence. This suggests that the middle Carboniferous stratigraphy of the Dniepr-Donets basin to the northwest probably contains significant amounts of fluvial sandstones, important for assessing hydrocarbon reservoir potential.

  20. Sedimentary geology of the middle Carboniferous of the Donbas region (Dniepr-Donets Basin, Ukraine). (United States)

    van Hinsbergen, Douwe J J; Abels, Hemmo A; Bosch, Wolter; Boekhout, Flora; Kitchka, Alexander; Hamers, Maartje; van der Meer, Douwe G; Geluk, Mark; Stephenson, Randell A


    The Paleozoic Dniepr-Donets Basin in Belarus, Ukraine, and Russia forms a major hydrocarbon province. Although well- and seismic data have established a 20 km thick stratigraphy, field-studies of its sediments are scarce. The inverted Donbas segment (Ukraine) exposes the middle Carboniferous part of the basin's stratigraphy. Here, we provide detailed sedimentological data from 13 sections that cover 1.5 of the total of 5 km of the Bashkirian and Moscovian stages and assess the paleoenvironment and paleo-current directions. Middle Carboniferous deposition occurred in a shelf environment, with coal deposition, subordinate fluvial facies, and abundant lower and middle shoreface facies, comprising an intercalated package of potential source and reservoir rocks. Sedimentary facies indicate a paleodepth range from below storm wave base to near-coastal swamp environments. Sedimentation and subsidence were hence in pace, with subtle facies changes likely representing relative sea-level changes. Paleocurrent directions are remarkably consistently southeastward in time and space in the different sedimentary facies across the Donbas Fold Belt, illustrating a dominant sedimentary infill along the basin axis, with little basin margin influence. This suggests that the middle Carboniferous stratigraphy of the Dniepr-Donets basin to the northwest probably contains significant amounts of fluvial sandstones, important for assessing hydrocarbon reservoir potential.

  1. A revision of tetrapod footprints from the late Carboniferous of the West Midlands, UK

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    Luke E. Meade


    Full Text Available A series of sandstone slabs from Hamstead, Birmingham (West Midlands, UK, preserve an assemblage of tetrapod trackways and individual tracks from the Enville Member of the Salop Formation (late Carboniferous: late Moscovian–Kasimovian. This material has received limited previous study, despite being one of the few British sites to preserve Carboniferous tetrapod footprints. Here, we restudy and revise the taxonomy of this material, and document it using 3D models produced using photogrammetry. The assemblage is dominated by large tracks assigned to Limnopus isp., which were made by early amphibians (temnospondyls. A number of similar but smaller tracks are assigned to Batrachichnus salamandroides (also made by temnospondyls. Dimetropus leisnerianus (made by early synapsids and Dromopus lacertoides (made by lizard-like sauropsids such as araeoscelids are also present. This ichnofauna contrasts with a slightly stratigraphically older, more extensive and better-studied assemblage from Alveley (Shropshire, which is dominated by small amphibians with relatively rare reptiliomorphs, but which lacks Dromopus tracks. The presence of Dromopus lacertoides at Hamstead is consistent with the trend towards increasing aridity through the late Carboniferous. It is possible that the assemblage is the stratigraphically oldest occurrence of this important amniote ichnotaxon.

  2. Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by 10Be cosmogenic radionuclide surface exposure dating (United States)

    Owen, L.A.; Finkel, R.C.; Barnard, P.L.; Haizhou, Ma; Asahi, K.; Caffee, M.W.; Derbyshire, E.


    Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and 10Be cosmogenic radionuclide (CRN) surface dating in study areas in southeastern (Gonga Shan), southern (Karola Pass) and central (Western Nyainqentanggulha Shan and Tanggula Shan) Tibet, and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands. Each of the study regions receives its precipitation mainly during the south Asian summer monsoon when it falls as snow at high altitudes. Gonga Shan receives the most precipitation (>2000 mm a-1) while, near the margins of monsoon influence, the Karola Pass receives moderate amounts of precipitation (500-600 mm a-1) and, in the interior of the plateau, little precipitation falls on the western Nyainqentanggulha Shan (???300 mm a -1) and the Tanggula Shan (400-700 mm a-1). The higher precipitation values for the Tanggula Shan are due to strong orographic effects. In each region, at least three sets of moraines and associated landforms are preserved, providing evidence for multiple glaciations. The 10Be CRN surface exposure dating shows that the formation of moraines in Gonga Shan occurred during the early-mid Holocene, Neoglacial and Little Ice Age, on the Karola Pass during the Lateglacial, Early Holocene and Neoglacial, in the Nyainqentanggulha Shan date during the early part of the last glacial cycle, global Last Glacial Maximum and Lateglacial, and on the Tanggula Shan during the penultimate glacial cycle and the early part of the last glacial cycle. The oldest moraine succession in each of these regions varies from the early Holocene (Gonga Shan), Lateglacial (Karola Pass), early Last Glacial (western

  3. Quaternary Glaciations in the Rio Mendoza Valley, Argentine Andes (United States)

    Espizua, Lydia E.


    In the Rio Mendoza valley, five Pleistocene drifts and one Holocene drift are distinguished by multiple relative-age criteria, including surface-rock weathering, development of rock varnish, moraine morphology, soil-profile development, and stratigraphic relationships. Several absolute ages suggest a preliminary chronology. During the oldest (Uspallata) glaciation, a system of valley glaciers flowed 110 km from the Andean drainage divide and 80 km from Cerro Aconcagua to terminate at 1850 m. Drift of this ice advance is older than a widespread tephra dated by fission-track at 360,000 ± 36,000 yr. During the Punta de Vacas advance, ice terminated at 2350 m, while during the subsequent Penitentes advance, the glacier system ended at 2500 m. A travertine layer overlying Penitentes Drift has U-series age of 24,200 ± 2000 yr B.P. The distribution of Horcones Drift, which is inferred to represent the last glacial maximum, delimits an independent ice stream that flowed 22 km down Horcones valley to 2750 m. A later readvance (Almacenes) reached 3250 m. Confluencia Drift is considered to be Neoglacial in age and extends downvalley to 3300 m. The moraine sequence is compared with those studied by Caviedes (1972) along Rio Aconcagua on the Chilean flank of the Andes.

  4. Discovery of Quaternary glacial evidence of Snow Mountain in Taiwan,China

    Institute of Scientific and Technical Information of China (English)


    There are glacial remains of three different periods on the main peak of Snow Mountain in Taiwan province,including cirque lake,crosswall,polished surface,striation,moraine etc.These three different periods were called,respectively,Shanzhuang ((44.25 ± 3.72) kaBP),Shuiyuan ((18.26 ± 1.52) kaBP),and Xueshan glacial stages (the late period of last glaciation).It is characterized by the earlier glacier broad in scale.

  5. Famennian glaciation in the eastern side of Parnaíba Basin, Brazil: evidence of advance and retreat of glacier in Cabeças Formation

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    Roberto Cesar de Mendonça Barbosa

    Full Text Available ABSTRACTGlaciotectonic features studied in the siliciclastic deposits of Cabeças Formation, Upper Devonian, represent the first evidence of Famennian glaciation in Southeastern Parnaíba Basin, Brazil. Outcrop-based stratigraphic and facies analyses combined with geometric-structural studies of these deposits allowed defining three facies association (FA. They represent the advance-retreat cycle of a glacier. There are: delta front facies association (FA1 composed of massive mudstone, sigmoidal, medium-grained sandstone with cross-bedding and massive conglomerate organized in coarsening- and thickening-upward cycles; subglacial facies association (FA2 with massive, pebbly diamictite (sandstone, mudstone and volcanic pebbles and deformational features, such as intraformational breccia, clastic dikes and sills of diamictite, folds, thrust and normal faults, sandstone pods and detachment surface; and melt-out delta front facies associations (FA3, which include massive or bedded (sigmoidal cross-bedding or parallel bedding sandstones. Three depositional phases can be indicated to Cabeças Formation: installation of a delta system (FA1 supplied by uplifted areas in the Southeastern border of the basin; coastal glacier advance causing tangential substrate shearing and erosion (FA1 in the subglacial zone (FA2, thus developing detachment surface, disruption and rotation of sand beds or pods immersed in a diamicton; and retreat of glaciers accompanied by relative sea level-rise, installation of a high-energy melt-out delta (FA3 and unloading due to ice retreat that generates normal faults, mass landslide, folding and injection dykes and sills. The continuous sea-level rise led to the deposition of fine-grained strata of Longá Formation in the offshore/shoreface transition in the Early Carboniferous.

  6. Rocky Mountain Spotted Fever (United States)

    ... facebook share with twitter share with linkedin Rocky Mountain Spotted Fever Rocky Mountain spotted fever is a ... New Mexico. Why Is the Study of Rocky Mountain Spotted Fever a Priority for NIAID? Tickborne diseases ...

  7. Mrar formation of western Libya - evolution of an early Carboniferous delta system

    Energy Technology Data Exchange (ETDEWEB)

    Whitbread, T. (Univ. of Keele, England); Kelling, G.


    The Lower Carboniferous Mrar Formation is exposed extensively along the southern margin of the Ghadames basin in northwest Libya. The basal part of the Mrar forms the cap rock and possible hydrocarbon source for many of the producing reservoirs in the underlying Tahara sandstones. Furthermore, the Mrar itself is known to contain significant gas shows southwest of the outcrop, associated with some oil potential. The Mrar formation was deposited in a deltaic environment which developed on the northern part of the stable Saharan platform. The history of the Mrar formation's deposition is discussed. (JMT)

  8. Metallogenesis of Devonian—Carboniferous Strata—bound Carbonate—type Uranium Deposits in South China

    Institute of Scientific and Technical Information of China (English)



    This paper deais with the geological conditions.mineralization characteristics,genetic types and space-time distribution of the Devonian-Carboniferous strata-bound carbonate-type uranium deposits in South China.These ore deposits are genetically classified as the leaching type and the leaching-hydrothermal superimposed type,These ore deposits are confined mainly to the strata (D2-3,C1)of platform-lagoon carbonate facies.Unique tectonic settings are a vital factor leading to the formation of these uranium deposits.A metallogenetic model for these uranium deposits has been proposed.


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    PALIU-POPA Lucia


    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.

  10. Pleistocene glaciation of volcano Ajusco, central Mexico, and comparison with the standard Mexican glacial sequence (United States)

    White, Sidney E.; Valastro, Salvatore


    Three Pleistocene glaciations and two Holocene Neoglacial advances occurred on volcano Ajusco in central Mexico. Lateral moraines of the oldest glaciation, the Marqués, above 3250 m are made of light-gray indurated till and are extensively modified by erosion. Below 3200 m the till is dark red, decomposed, and buried beneath volcanic colluvium and tephra. Very strongly to strongly developed soil profiles (Inceptisols) have formed in the Marqués till and in overlying colluvia and tephra. Large sharp-crested moraines of the second glaciation, the Santo Tomás, above 3300 m are composed of pale-brown firm till and are somewhat eroded by gullies. Below 3250 m the till is light reddish brown, cemented, and weathered. Less-strongly developed soil profiles (Inceptisols) have formed in the Santo Tomás till and in overlying colluvia and tephra. Narrow-crested moraines of yellowish-brown loose till of the third glaciation, the Albergue, are uneroded. Weakly developed soil profiles (Inceptisols) in the Albergue till have black ash in the upper horizon. Two small Neoglacial moraines of yellowish-brown bouldery till on the cirque floor of the largest valley support weakly developed soil profiles with only A and Cox horizons and no ash in the upper soil horizons. Radiocarbon dating of organic matter of the B horizons developed in tills, volcanic ash, and colluvial volcanic sand includes ages for both the soil-organic residue and the humic-acid fraction, with differences from 140 to 660 yr. The dating provides minimum ages of about 27,000 yr for the Marqués glaciation and about 25,000 yr for the Santo Tomás glaciation. Dates for the overlying tephra indicate a complex volcanic history for at least another 15,000 yr. Comparison of the Ajusco glacial sequence with that on Iztaccíhuatl to the east suggests that the Marqués and Santo Tomás glaciations may be equivalent to the Diamantes glaciation First and Second advances, the Albergue to the Alcalican glaciations, and the

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

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    Mark James Hopwood


    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.

  12. Chemostratigraphy and lithological characters of Neoproterozoic cap carbonates from the Kuruktag Mountain, Xinjiang, western China

    Institute of Scientific and Technical Information of China (English)


    The Neoproterozoic Era includes some of the most largest ice ages in the geological history.The exact number of glaciations is unknown,though there were at least two events of global glaciation.Neoproterozoic glacial deposits in the Kurukmg Mountain,Xinjiang,western China have proven that there had occurred three discrete Neoproterozoic glaciations.Diamictite units occurred in the Bassi,Tereeken,and Hankalchough formations,carbonate units were recognized among the diamictites and immediately overlied the Bayisi,Tereeken and Hankalchough diamictites.Carbonates at the top of the Bayisi Formation are characterized by the dolo-sility stones with negative δ13C values ranging from-4.10‰ to-8.17‰(PDB),comparable to the Sturtian cap carbonates that overlie the Sturtian glacial deposits from other Neoproterozoic sequences.Carbonates overlying the Tereeken Formation are characterized by the pinkish cap dolostones fca.10 m thick)with negative δ13C values railging from -2.58‰ to-4.77‰(PDB),comparable to the Marinoan cap carbonates,The cap is alao characterized by tepee-like structures,barite precipitates and pseudomorphous aragonite crystal fan limestones.Carbonates at the top of the Hankalchough Formation are characterized by subaerial exposure crust(vadose pisolite structure,calcareous crust structure)dolostones with negative δ13C values ranging from-4.56‰δto-11.45‰(PDB)and the calcareous crust dolostones,implying that the Hankalchough cap carbonates differ from either the Sturtian or Marinoan cap carbonates in sedimentary environment and carbon isotopic composition.In addition,it is suggested the Hankalchough glaciation belongs to a terrestrial glaciation and it is the third largest glaciation during the Neoproterozoic period on the Tarim platform.

  13. Control of favorable lithology on Jinlongshan micro-fine disseminated gold deposits, southern Qinling Mountains

    Institute of Scientific and Technical Information of China (English)

    赵利青; 冯钟燕


    Jinlongshan gold orebelt, a newly discovered one in sedimentary rock region in southern Qinling Mountains, is mainly located in upper Devonian and lower Carboniferous calcareous siltstone and argillic silty limestone of later Paleozoic era. Typical disseminated gold mineralization occurred in calcareous siltstone, which is major host rock and mainly composed of silt (SiO2 mostly varies from 38% to 73%) and calcite (CaO mostly varies from 10% to 25%). Pyrite created by living beings in Nanyangshan formation may be poor in gold. Faults and favorable layers jointly control disseminated gold mineralization. The significance of this opinion is very great for gold exploration.

  14. Ancient Changjiang channel system in the East China Sea continental shelf during the last glaciation

    Institute of Scientific and Technical Information of China (English)

    LI Guangxue; LIU Yong; YANG Zigeng; YUE Shuhong; YANG Wenda; HAN Xibin


    Based on the data of high-resolution seismic profiles, an ancient river channel system of the last glaciation occurred along the Zhedong and Xihu depression in the southeast of Hupijiao rise. The distribution of the channel fill system shows that the ancient Changjiang River went through the Changjiang depression into the low land plain of the outside continental shelf during the low sea level cycle of the last glaciation. The big channel fill into Okinawa Trough is not found due to the depletion of the river kinetic energy in the low land plain. The river discharge dispersal was of an important role to the dilution of the northern Okinawa Trough sea at that time. Six ancient river channel systems (A―F), which are main distributaries of ancient Changjiang in the East China Sea continental shelf during the last glaciation, may be buried off the modern Changjiang estuary. The distribution of these channels coincides with the zonal elevations in the sea floor.

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

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    D. Korn


    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

  16. Biostratigraphic and sequence stratigraphic relationships of Upper Carboniferous conodont and foraminifer distribution, Canadian Arctic Archipelago

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, Charles M. [Calgary Univ., AB (Canada). Dept. of Geology and Geophysics; Pinard, S. [Geological Survey of Canada, Calgary, AB (Canada). Inst. of Sedimentary and Petroleum Geology; Beauchamp, B. [Geological Survey of Canada, Calgary, AB (Canada). Inst. of Sedimentary and Petroleum Geology


    The distribution of conodonts (CMH) and small foraminifers (SP) were documented in 2 Upper Carboniferous stratigraphic sections from the Sverdrup Basin. Conodont zonation was correlated with zones from the Russian platform. This finding is supported by ammonoid (Nassichuk and Henderson, 1986) and fusulinacean (Nassichuk and Rui Lin, 1992) data. It was found that facies control of conodonts and small foraminifers must be accounted for when making interregional correlations. The integration of biostratigraphic data with sequence stratigraphic data to reduce correlation pitfalls was demonstrated. Correlations between the Canadian Arctic and the Upper Moscovian to lower Gzhelian succession of the Russian Platform was discussed, with an emphasis on the Kasimovian. The base of the Kasimovian is recognizable by the close correspondence of the base of Streptognathodus gracilis-S. ippletus Zone and the Hemigordius Nodosinelloides-Protonodosaria Zone. Three foraminifer genera appear at this level with the absence of clear ancestors in underlying Moscovian strata. The underlying strata represent a speciation event in the genus Streptognathodus and Upper Carboniferous to Lower Permian conodont lineage. Variations in species ranges between Canadian Arctic and Russian Platform may be related to variation of boundary positions within a stratigraphic sequence.

  17. Changes in dominance patterns in upper Carboniferous plant-fossil assemblages (United States)

    Pfefferkorn, Hermann W.; Thomson, Margaret C.


    Upper Carboniferous (Pennsylvanian) terrestrial clastic rocks from North America and Europe contain compression-impression plant-fossil assemblages that represent the remains of plant communities that grew on floodplains, levees, and other clastic facies of fluvial and deltaic lowlands. Quantitative analysis of 66 plant-fossil assemblages spanning the entire late Carboniferous demonstrates that before the middle of the Westphalian D Stage the majority of plant-fossil assemblages are dominated by pteridosperms and sphenopsids. Lycopods and cordaites dominate only a few assemblages counted. Ferns do not dominate any assemblages. These findings contrast sharply with the dominance of lycopods reported by others from coal swamps of the same time interval. Above the middle of the Westphalian D, however, one-third of the compression-impression assemblages counted are dominated by ferns. The change in dominance pattern in compression-impression plant-fossil assemblages occurs half a stage earlier than the previously reported change from lycopod-dominated to fern-dominated assemblages at the Westphalian-Stephanian boundary in coal swamps. A trend toward dryer climate during Westphalian D apparently influenced plants growing on better-drained alluvial soils earlier than those growing on water-logged soils of contemporaneous coal swamps. *Present address: Room 108 Math.-Geology Building, University of Minnesota, Duluth, Minnesota 55812

  18. A Carboniferous non-onychophoran lobopodian reveals long-term survival of a Cambrian morphotype. (United States)

    Haug, Joachim T; Mayer, Georg; Haug, Carolin; Briggs, Derek E G


    Lobopodians, a nonmonophyletic assemblage of worm-shaped soft-bodied animals most closely related to arthropods, show two major morphotypes: long-legged and short-legged forms. The morphotype with stubby, conical legs has a long evolutionary history, from the early Cambrian through the Carboniferous, including the living onychophorans and tardigrades. Species with tubular lobopods exceeding the body diameter have been reported exclusively from the Cambrian; the three-dimensionally preserved Orstenotubulus evamuellerae from the uppermost middle Cambrian "Orsten" (Sweden) is the youngest long-legged lobopodian reported thus far. Here we describe a new long-legged lobopodian, Carbotubulus waloszeki gen. et sp. nov., from Mazon Creek, Illinois, USA (∼296 million years ago). This first post-Cambrian long-legged lobopodian extends the range of this morphotype by about 200 million years. The three-dimensionally preserved specimen differs significantly from the associated short-legged form Ilyodes inopinata, of which we also present new head details. The discovery of a Carboniferous long-legged lobopodian provides a more striking example of the long-term survival of Cambrian morphotypes than, for example, the occurrence of a Burgess Shale-type biota in the Ordovician of Morocco and dampens the effect of any major extinction of taxa at the end of the middle Cambrian.

  19. Mountain biodiversity patterns at low and high latitudes. (United States)

    Molau, Ulf


    This paper presents an overview of mountain biodiversity at a multitude of scales in space, time, and function. Even though species richness is usually the focal component in nature conservation, genetic diversity within species is equally important. The small-scale distribution of species in the tropical Andes, as exemplified by the plant genera Calceolaria and Bartsia, contrasts against the situation in high-latitude mountains, e.g., the Scandes, where species have wide ranges and many are circumpolar. Recent studies on alpine plants based on molecular methods show that the intraspecific genetic diversity tends to increase with latitude, a situation brought about by the glaciation history with repeated contraction-expansion episodes of species' distributions. In tropical mountains, species distributions are geographically much narrower, often as a result of relatively recent, local speciation. Thus, whereas species richness in mountains decreases from the Equator towards the poles, genetic diversity shows the opposite trend. Finally, a comparison of ecosystem diversity in low- and high-latitude mountain ranges (tropical Andes vs. Scandes) shows that the landscapes differ profoundly with regard to timberline ecotones, snow distribution, and climate variables, and are subject to widely different impacts of global change

  20. Devonian/Carboniferous boundary glacioeustatic fluctuations in a platform-to-basin direction: A geochemical approach of sequence stratigraphy in pelagic settings (United States)

    Bábek, Ondrej; Kumpan, Tomáš; Kalvoda, Jiří; Matys Grygar, Tomáš


    We investigated high-resolution stratigraphic distribution of selected major and trace elements and gamma-ray spectra of fourteen Devonian/Carboniferous (D/C) boundary sections of Europe located in the late Palaeozoic Laurussia and Gondwana. The aim was to trace the geochemical signature of a marked forced and normal regressive interval which was associated with rapid progradation of siliciclastics into the marine carbonate systems (Rhenish Massif) and a prominent hiatus in shallow-water ramp settings (Namur-Dinant Basin). This interval represents the late Devonian Hangenberg event (HBE) sensu lato (middle praesulcata conodont zone) as defined by previous authors. This regressive interval (FSST to LST) correlates with thin shale layers (HBE shale) sandwiched between monotonous nodular calcilutite/calcisiltite successions at five pelagic sections of Moravia, Carnic Alps, Montagne Noire, and Pyrenees. In all sections with continuous D/C sedimentation (i.e., except those of the Namur-Dinant Basin), the HBE s.l. interval is accompanied by elevated percentages of detrital proxies (Al, K, Rb, Zr) and changes in their ratios (Zr/Rb, K/Al, Rb/K) which are normally interpreted as indicators of increased siliciclastic input, provenance, and grain size. Zr/Rb and other proxies are traceable even without apparent lithological evidence and can, therefore, facilitate stratigraphic correlation. Paleoredox and productivity proxies (U/Th and Ni/Rb enrichment factors) only rarely show elevated values in the Hangenberg black shale interval, indicating that the associated water dysoxia/anoxia was a local rather than global phenomenon. Global correlations based on the HBE black shales should therefore be dropped in favor of the HBE s.l. interval. Moreover, analysis of sedimentation rates in the upper expansa to kockeli zone interval using the published radiometric ages suggests that the HBE s.l. was a time of significant increase in the rate of siliciclastic supply into the ocean, even

  1. New glacoated area in Rodna mountains-Tarnița la Cruce cirque

    Directory of Open Access Journals (Sweden)

    Marcel MÎNDRESCU


    Full Text Available Even though we refer just to one former glacial site in the Rodna mountain area, this is important from several points of view, firstly, this one was missed by previous researchers because of its lateral position from the axis of glaciation, the main ridge of the Rodna Mountains. Secondly, the cirque, with its altitude and shape,completes a population of cirques less represented in the Eastern Carpathians, compared with the Alps of Transylvania. These are called alpine cirques in the world literature, but we prefer this term of ‘Carpathian’ to fit better with the geomorphologic reality of the Romanian Carpathians. These alpine cirques have small dimensions, with apron floors where there were cold glaciers (in the ablationand accumulation areas situated inside the cirque but short ones, which ended immediately after the floor, without being continued by glacier tongues. Nowadays, after the disappearance of Quaternary glaciers, these appear hanging on the high mountain ridges (being also valley-side cirques, far from the bottom of the valleys,and have a clean aspect. Finally, this mountainous site is important and interesting, at the same time, because it is a natural mountainous environment, untouched by pollution and human influence, and very sensitive to the environmental changes. It is a ‘fresh’ glaciated site which undergoes changes because of the ending of glaciation,so any change of the environment will be sensed by its ecosystem. Therefore, this area represents a potential site for scientific research to evaluate the impact of present changes in the environment.

  2. 36Chlorine exposure dating of a terminal moraine in the Galicica Mountains, Macedonia (United States)

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


    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.

  3. 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


    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.)

  4. Aspects of late devonian and early carboniferous palynology of southern Ireland. III. Palynology of devonian—carboniferous transition sequences with special reference to the bantry bay area, co. cork

    NARCIS (Netherlands)

    Zwan, C.J. van der


    The present paper provides: (1) an analysis of the qualitative and quantitative compositional development of Late Devonian-Early Carboniferous palynological assemblages from the Bantry Bay and other sections of southern Ireland; (2) a scheme of successive phases, (inter) regionally recognizable in t

  5. Application of fluid flow systems analysis to reconstruct the post-Carboniferous hydrogeohistory of the onshore and offshore Netherlands

    NARCIS (Netherlands)

    Verweij, J.M.


    The reconstruction of the post-Carboniferous hydrogeohistory of the onshore and offshore Netherlands is part of an ongoing TNO project on fluid flow systems analysis on geological timescales. The scope of the project is to assess the present-day hydrogeological and fluid flow conditions of the

  6. Petroleum exploration of shallow marine deposit Carboniferous volcanic tuff reservoir in the western margin of Junggar Basin

    Institute of Scientific and Technical Information of China (English)

    Wang Jianyong; Wang Xuezhong; Ma Liqun


    In 2011,petroleum exploration of shallow marine deposits Carboniferous and volcanic tuff reservoir re-alized breakthroughs at Chepaizi slope in the western margin of Junggar Basin. Pai 61 well ,with 855.7 ~949.6 m section,in the conventional test oil obtained 6 t/d industrial oil flow. The surface viscosity is 390 mPa· s (50℃). The marine deposit of Carboniferous are deep oil source rocks and high-quality reservoir. Magma volcanic activity provides the basis for volcanic reservoir development and distribution. The weathering crust and secondary cracks developed volcanic tuff by strong rock weathering and dissolution of organic acids which has become top quality reservoir. Deep Permian oil-gas migrated and accumulated to high parts along Hong-Che fault belt and stratigraphic unconformity stripping. Permian and Triassic volcanic rocks or dense mudstone sedimentary cover as a regional seal for the late Carboniferous oil-gas to save critically. The seismic pre-stack time migration processing technologies for the problem of poor inner structures of Carboniferous were developed. Response of volcanic rock seismic and logging are obvious. The application imaging logging and nuclear magnetic technology achieved the qualitative identification and quantification of fracture description.

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

  8. Organic facies characteristics of the Carboniferous Pamucakyayla Formation, western Taurus, Antalya Nappes, Kemer (Antalya/Turkey) (United States)

    Bertan Gulludag, Cevdet; Altunsoy, Mehmet; Ozcelik, Orhan


    The study area is located in the western part of the Taurus Belt (SW Turkey). This region exhibits a complex structure involving two autochthonous units surrounded and imbricated with three allochthonous complexes. Antalya Nappes is a complex tectonic imbricate structure including sedimantary and ultrabasic rocks. In this study, organic facies characteristics of Carboniferous coaly units in the Pamucakyayla region (Kemer, Antalya-Turkey) were examined. The Carboniferous Pamucakyayla Formation, which is characterized by sandstone, claystone, marl and coaly units. This units includes different levels of coal seams in different thicknesses. Organic matter is composed predominantly of woody and amorphous material, with a minor contribution of planty and coaly material. Kerogen in the deposits is type II/III, as indicated by organic petrographic observations and Rock-Eval data. Total organic carbon (TOC) values are generally between 0.01 and 1.44 %, but reach 5.81 % in the formation. Tmax values vary between 446 and 451 °C and indicate mature zone (Based on the value of 0.25 % TOC). Organic facies type BC, C and CD were identified in the investigated units. Organic facies BC is related sandstoneand marl lithofacies. This facis is deposited under an anoxic water column in a fine grained clastics, where rapid deposition creates anoxia in the sediments after deposition. This facies is characterized by average values of HI around 317 (equivalent to type II kerogene), TOC around 0.02 %, and an average of S2 of 0.04 mg HC/g of rock. Organic facies C is related to sandstone, marl and coal lithofacies. This facies is characterized by average values of HI around 176 (equivalent to type III kerogene), TOC around 0.19 %, and an average of S2 of 0.03 mg HC/g of rock. The organic matter is partly oxidized, and terrestrial. Organic facies C is the "gas-prone" facies. Organic facies CD is related to limestone, marl and coal lithofacies. This facies is characterized by average values

  9. A first estimate of mountain permafrost distribution in the Mount Cook region of New Zealand’s southern alps


    Allen, S; Owens, I.; Huggel, C


    The heavily glaciated Mount Cook Region of New Zealand has experienced several recent large rock instabilities, but permafrost conditions related to these events remain unknown. This work presents the first systematic approach for investigating the distribution of mountain permafrost in New Zealand. At this level of the investigation, a firstorder estimate is based upon the adaptation of established topo-climatic relationships from the European Alps. In the southeast of the study region...

  10. Simulating the amplification of orbital forcing by ocean feedbacks in the last glaciation. (United States)

    Khodri, M; Leclainche, Y; Ramstein, G; Braconnot, P; Marti, O; Cortijo, E


    According to Milankovitch theory, the lower summer insolation at high latitudes about 115,000 years ago allowed winter snow to persist throughout summer, leading to ice-sheet build-up and glaciation. But attempts to simulate the last glaciation using global atmospheric models have failed to produce this outcome when forced by insolation changes only. These results point towards the importance of feedback effects-for example, through changes in vegetation or the ocean circulation-for the amplification of solar forcing. Here we present a fully coupled ocean-atmosphere model of the last glaciation that produces a build-up of perennial snow cover at known locations of ice sheets during this period. We show that ocean feedbacks lead to a cooling of the high northern latitudes, along with an increase in atmospheric moisture transport from the Equator to the poles. These changes agree with available geological data and, together, they lead to an increased delivery of snow to high northern latitudes. The mechanism we present explains the onset of glaciation-which would be amplified by changes in vegetation-in response to weak orbital forcing.

  11. Carboniferous Bimodal Volcanic Rocks and Their Plate Tectonic Setting,Hainan Island

    Institute of Scientific and Technical Information of China (English)

    夏邦栋; 施光宇; 等


    The Carboniferous volcanic rocks in western Hainan Island consist of a series of oceanic tholeite and rhyoporphyrite,showing bimodal nature.Similar geochemical characters,in terms of abun-daces and relative rations of incompatible elements and REE and the REE patterns,between the basalt and continental rift-associated tholeiite indicate the occurrence of Late Paleozoic rifting in the area.The basaltic magma,with a low degree of evolution,was originated from deep mantle,show-ing contamination by low crustal material.The rhyolite is thought to be formed from partial melting of the continental crust by higher thermal flow in a rift environment rather than from fractional crystallization of a basaltic magma.


    Directory of Open Access Journals (Sweden)

    Robin Mujačić


    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


    Directory of Open Access Journals (Sweden)



    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. 

  14. The smallest Neoptera (Baryshnyalidae fam. n. from Hagen-Vorhalle (early Late Carboniferous: Namurian B; Germany

    Directory of Open Access Journals (Sweden)

    Jan-Michael Ilger


    Full Text Available With Baryshnyala occulta gen. et sp. n. (Baryshnyalidae fam. n. we report a new small species from early Late Carboniferous (Pennsylvanian deposits in Hagen-Vorhalle. It differs in its unique venation pattern and small size from all other Neoptera known from this Lagerstätte and other contemporaneous locations worldwide. With an estimated wing length of <10mm it is by far the smallest species of Neoptera from Hagen-Vorhalle and is less than half as long as Heterologopsis ruhrensis Brauckmann & Koch, 1982 (~25mm. The specimen shows some relations to the earliest Holometabola and may date back the first appearance of holometaboly to the Namurian B (early Bashkirian: Marsdenian. The new species increases the paleo-biodiversity and span of inter-specific variability within the early Neoptera. It shows that very small and tiny specimens and species can easily be overlooked.

  15. Magmatism of the Shuteen Complex and Carboniferous subduction of the Gurvansaikhan terrane, South Mongolia (United States)

    Batkhishig, Bayaraa; Noriyoshi, Tsuchiya; Greg, Bignall


    The Carboniferous Shuteen Complex, a volcano-plutonic ring complex associated with Cu-Au porphyry mineralization, is located in the Gurvansaikhan island arc terrane of South Mongolia. This paper presents new data on the petrography, major and trace element chemistry, and Sr-Nd isotopic chemistry of the Shuteen Complex. We discuss the relationship between volcanic and plutonic rocks of the complex, and consider their similarity to high-Al 2O 3 trondhjemite-tonalite-granodiorite and adakites. We also consider the origin, magma source, and dynamic processes of the Shuteen Complex; propose a petrogenetic model; and investigate the composition of the subducting slab and the features of arc volcanism at the time. We assess some of the magmatic processes likely to have occurred within the Shuteen Complex, such as Carboniferous slab subduction and partial melting, and examine their influence on magma composition. The Shuteen Complex is geochemically similar to adakite-type rocks. The complex is silica-saturated (SiO 2 ⩾ 56%), rich in Al 2O 3 (⩾15%), MgO (400 ppm), and depleted in high field strength elements. It also has a high Sr/Y value, and ( 87Sr/ 86Sr) I arc setting, and partial melting was the dominant process during petrogenesis. The primary Shuteen magma had an adakitic composition and was probably derived from the partial melting of subducting oceanic crust, possibly with minor local interaction with mantle material. The results of quantitative modelling of mass balance and partial melt equilibrium for the magma source indicate that the subducting slab contained oceanic basalt and a minor component of oceanic sediment, which together with a restite eclogite phase formed the source of the Shuteen magma. The conclusive results of this study provide new insights into the magmatic evolution of the Shuteen Complex.

  16. Understanding the mobilisation of metal pollution associated with historical mining in a carboniferous upland catchment. (United States)

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


    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.

  17. Predicting methane accumulations generated from humic Carboniferous coals in the Donbas fold belt (Ukraine)

    Energy Technology Data Exchange (ETDEWEB)

    Alsaab, D.; Elie, M.; Izart, A.; Sachsenhofer, R.F.; Privalov, V.A. [Paradigm Co., Nancy (France)


    The numerical modeling of the Ukrainian part of the Donbas fold belt indicates that the coalification pattern was controlled mainly by the maximum burial depth of coal seams and the heat flow (HF) (40-75 mW/m{sup 2}) during the Permian. The coalification pattern was overprinted by magmatic events during the Late Permian in the south syncline (150 mW/m{sup 2}) and during the Permian-Triassic in the north of the Krasnoarmeisk region (120 mW/m{sup 2}). The coalification pattern shows a strong increase in vitrinite reflectance values toward the east and southeastern parts of the study area likely caused by (1) an eastward increase in burial depth, (2) a probable eastward increase in HF, and, (3) probable magmatic activity. An increase in total erosion toward the eastern and southeastern parts was also observed with a maximum erosional amount of approximately 8 km (5 mi) in the southeastern part of the study area. The basin modeling of this area predicts that the main phase of hydrocarbon generation occurred during the Carboniferous-Early Permian subsidence. The magmatic events that occurred during the Permian-Triassic caused renewed pulses of hydrocarbon generation. A large amount of the generated hydrocarbons was lost to the surface because of a lack of seals. However, the numerical simulation predicts accumulations of about 2 tcf (57 billion m{sup 3}) of methane generated from Carboniferous coals in the south and main synclines, where Lower Permian seal rocks are preserved. Finally, this study provides data on methane resources along the northern flank

  18. 准噶尔盆地春晖油田石炭系火山岩储层控制因素分析%Controlling factors of the Carboniferous volcanic reservoirs in the Chunhui Oil Field, Junggar Basin

    Institute of Scientific and Technical Information of China (English)



    春晖油田石炭系火山岩地层中,油气富集程度与储层发育程度呈正相关关系。研究认为,储层的发育与分布主要受岩相、岩性和构造运动的控制。岩相控制岩性,岩性控制储集空间组合类型,溢流相和火山沉积相围绕爆发相具有环带状分布特点,从火山角砾岩→玄武岩、安山岩→凝灰岩,储集性能逐渐变差;构造运动则控制裂缝的发育及溶蚀作用,断层周边微裂缝发育,沿着微裂缝则溶蚀作用增强,次生孔隙发育。%The Chunhui Oil Field in the Junggar Basin lies in the western part of the Halaalate Mountain tectonic zone, in which the Carboniferous volcanic strata consist dominantly of the volcanic rocks such as tuff, andesite, basalt and volcanic breccias. There is a positive correlation between the hydrocarbon enrichment and reservoir development in the Carboniferous volcanic reservoir rocks from the Chunhui Oil Field. The distribution and development of the volcanic reservoir rocks are primarily controlled by lithofacies, lithology and tectonism. On the whole, the lithofacies may exercise a major control on lithology of the volcanic reservoir rocks, which, in turn, may control the reservoir spaces types. The volcanic rocks in the Chunhui Oil Field exhibit a trend of the girdle pattern of lithofacies changes from the explosive facies through the effusive facies to the volcano-sedimentary facies. The reservoir capacity is gradually getting poor and poor from volcanic breccias to basalt and andesite and finally to tuff. The tectonism is also believed to be a major control on the fissure development and dissolution. The structural stress may give rise to the formation of the cracks or fissures in the brittle rocks, which may greatly improve the reservoir spaces of the Carboniferous volcanic reservoir rocks in the study area.

  19. Sedimentary Records of Shelf Edge Glaciation: A Young Trough-Mouth Fan on the Gulf of Alaska Yakutat Margin (United States)

    Swartz, J. M.; Gulick, S. P. S.; Goff, J. A.


    The St. Elias Mountains in Southeastern Alaska are an active orogen that host temperate marine glaciers. Here, ice streams advancing across the continental shelf during glacial periods create wide shelf-crossing troughs and deliver large sediment volumes directly to the shelf edge, and from there to the continental slope and the deep sea Surveyor Fan. The continental slope exhibits steep morphology (~10°-30°), controlled by the Transition Fault, a transform boundary between the Yakutat micro-plate and the Pacific plate. Prior statistical analysis of continental slope morphology indicates that these steep initial slope conditions have been modified by proximal sedimentation during repeated glacial advances. Downslope of the Yakutat Sea Valley an incipient trough-mouth fan exists while between the troughs and downslope of the Alsek Sea Valley sediment slope-bypass dominates. Seismic analysis indicates that the Yakutat margin has seen significant slope sedimentation since the intensification of northern hemisphere glaciation ~2.6 Ma, but it is only recently that sufficient sediment supply has existed to overwhelm the steep margin topography and form the young trough-mouth fan. The mid-Pleistocene climate transition at ~1 Ma, and its associated shift from 41Kyr to 100Kyr glacial-interglacial climate cycles, could have potentially allowed sustained ice stream advances to the shelf edge and associated high proximal sedimentation on the continental slope. Integration of seismic data and newly obtained age constraints from recent IODP cores allows for investigation into the timing of Yakutat trough-mouth fan sedimentation and its relation to climate transitions.

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

    Weber, Martin; Baewert, Henning; Morche, David


    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

  1. Acute mountain sickness (United States)

    High altitude cerebral edema; Altitude anoxia; Altitude sickness; Mountain sickness; High altitude pulmonary edema ... Acute mountain sickness is caused by reduced air pressure and lower oxygen levels at high altitudes. The faster you ...

  2. Geochemistry of amphibolites and related graphitic gneisses from the Suchý and Malá Magura Mountains (central Western Carpathians) – evidence for relics of the Variscan ophiolite complex


    Ivan Peter; Méres Štefan


    Three small bodies of amphibolites and associated graphitic gneisses from the Suchý and Malá Magura Mountains (Tatric Megaunit, central Western Carpathians) have been studied by petrographic and geochemical methods. Isolated, fault-bounded bodies first hundreds of meters in size are located in the complex of the Early Paleozoic paragneisses and migmatites intruded by the Lower Carboniferous granitoid rocks. Amphibolites (locally actinolite schists) were formed from effusive basalts, dolerites...

  3. Relief Evolution in Tectonically Active Mountain Ranges (United States)

    Whipple, Kelin X.


    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.

  4. Reconnaissance surficial geologic map of the Taylor Mountains quadrangle, southwestern Alaska (United States)

    Wilson, Frederic H.


    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.

  5. Provisional geological map of the Southern Cantabrian Mountains (Spain)

    NARCIS (Netherlands)

    Boschma, D.


    The area is mainly covered by Carboniferous sediments. Only two Devonian structures are present. The Devonian yielded sufficient fossils from Eifelian up to Famennian but in the Carboniferous fossils are scarce. Permian and Triassic cover the area unconformably in the east. In the Carboniferous seve

  6. Coal and oil shale of Early Carboniferous age in northern Canada - significance for paleoenvironmental and paleoclimatic interpretations. [Canada - Northwest Territories and Yukon Territory

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, A.R.; Goodarzi, F.; Potter, J. (Geological Survey of Canada, Calgary, AB (Canada))


    Lower Carboniferous (Mississippian) coal beds and oil shale occur at several locations in northern Canada. In the northern Yukon Territory coal of semi-anthracite/anthracite rank occurs in the Kayak Formation in the British Mountains and at Hoidahl Dome near the headwaters of Blow River. Farther south in the Liard Basin, Northwest Territories, coals of high volatile bituminous rank occur in the Mattson Formation. In the Arctic Islands thicker beds of the Emma Fiord Formation, the oldest unit in the Sverdrup Basin, contain thin coal seams and oil shale on Devon Island, near the southern edge of the basin and on Axel Heiberg and Ellesmere islands on the north side of the basin. Organic matter in the Devon Island section is at a low maturity level (R[sub o, max] % 0.26-0.50), whereas that from Ellesmere and Axel Heiberg has reached the level of meta-anthracite. Depositional environments for these carbonaceous sediments were different. The coal-bearing Kayak strata accumulated in a coastal plain setting overlain transgressively by younger marine beds. The Mattson coal beds appear to have formed in a prograding delta, but coal and oil shale in the Emma Ford were deposited in lacustrine environments in a rift basin. These Canadian occurrences resemble penecontemporaneous deposits in Svalbard and elsewhere, adjacent to the present-day Arctic Ocean. They formed at low latitudes where conditions were favourable for the preservation of carbonaceous matter. Prior to the opening of the Arctic Ocean basin in Mesozoic times, sites on the mainland were undoubtedly closer to sites in the Arctic Islands than they are today.

  7. Deformation patterns of the Carboniferous, illustrated by the example of the Harpstedt district in Northern Germany; Deformationsstile des Karbon am Beispiel des Gebietes Harpstedt, Norddeutschland

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, H. von [Niedersaechsisches Landesamt fuer Bodenforschung, Hannover (Germany)


    The Carboniferous basin of North West Germany is part of the piedmont basin north of the Variscides stretching from Ireland and England to France, Germany, and Poland. In the West German part of the piedmont basin, the Prepermian Jurassic and Cretacious took part in the development of the Lower Saxon basin and tectogenic. This results in a highly complex seismic deformation picture. For example, in the Harz mountains, deformations of the former piedmont basin are developed in the Culm facies, but the further direction of deformation remains unclear. Hydrocabon explorations in the North West German basin also developed the Prepermian underground strata. 3D seismic exploration provided a three-dimensional image of the region. A 3D seismic measurement made aAt the southern edge of Pompeckj's block was evaluated in order to obtain information on the deformation pattern and its interdependence with a Variscan piedmont basin deformation. [German] Das Nordwestdeutsche Karbonbecken ist Teil des noerdlich des variszischen Orogens vorgelagerten Vorlandbeckens. Dieses Becken erstreckt sich von Irland und England ueber Frankreich, Deutschland bis nach Polen. Im westdeutschen Teil des Vorlandbeckens wird das praepermische Stockwerk im Jura und in der Kreide in die Entwicklung des Niedersaechsischen Beckens und des Niedersaechsischen Tektogens einbezogen. Hierdurch werden aeltere Deformationen ueberpraegt und die seismische Abbildung so komplex, dass kaum noch Aussagen ueber einen frueheren Deformationszustand gemacht werden koennen. Im Harz ist die Deformationen des ehemaligen Vortiefenbeckens z.B. in der Kulmfazies aufgeschlossen. Der weitere Verlauf der Deformation in Richtung Vorland ist jedoch unklar. Durch die Kohlenwasserstoffexploration im Nordwestdeutschen Becken wurde auch der praepermische Untergrund erschlossen. Die 3D-Seismik ermoeglicht es, sich ein dreidimensionales Bild dieses Gebietes zu verschaffen. Am suedlichen Rand der Pompeckjschen Scholle wurde eine

  8. Record and time of Neoproterozoic glaciations on Earth%全球新元古代冰期的记录和时限

    Institute of Scientific and Technical Information of China (English)

    赵彦彦; 郑永飞


    events during chemical deposition. Extreme oxygen isotope records in minerals and rocks are also a geochemical proxy for continental glaciation. Examination of available data for geochronology, sedimentary geology and isotope geochemistry indicates that there were four main glacial episodes on Earth during the Neoproterozoic. They are named as the Kaigas (757 ~741Ma), Sturtian (718 ~660Ma) , Marinoan (651 ~635Ma) , and Gaskiers (583.7 ~582.1Ma) iceages. The Marinoan glaciation is of oceanic origin with the global scale, corresponding to the snowball Earth event The Sturtian glaciation may be of marine origin and was mainly deposited in the transitional facies from marine to continental margin. The Kaigas and Gaskiers glaciations are of continental or mountain origin and they occurred before and after the snowball Earth event, respectively. Although no sedimentary records have been recognized in South China for the Kaigas and Gaskiers glaciations, the abnormally negative carbon and oxygen isotope records provide the geochemical proxy for continental deglacial meltwater in the two episodes. Therefore, both geological and geochemical records can be used to retrieve the ancient glacial events in the history of Earth.

  9. Facing the Gamburtsev Subglacial Mountains: What other ranges do they look like? (United States)

    Creyts, T. T.; Ferraccioli, F.; Bell, R. E.; Wolovick, M.; Corr, H.; Jordan, T. A.; Frearson, N.; Damaske, D.; Rose, K. C.; Braaten, D. A.; Finn, C.


    Mountain ranges serve as nucleation sites for continental ice sheets over multiple glacial cycles. During warmer interglacial periods, such ranges provide a toe-hold for snow accumulation and small glaciers that expand as temperatures drop in response to declining carbon dioxide levels. Once an ice sheet grows beyond a critical size, its basal thermal regime favors melting and development of water networks. Studies of deglaciated ice sheet beds indicate a complex thermal regime where cold-based areas are interspersed with warm, temperate areas. The Gamburtsev Subglacial Mountains are a massive range in central East Antarctica. They are Earth's only completely ice-covered mountain range. Results from ice penetrating radar reveal steep headwalls with semicircular planform lying along high ridges and with peaks above 2500 m in the central mountain core. These likely represent cirque headwalls and provide evidence for widespread mountain glaciers within the Gamburtsevs. Headwalls are often accompanied by discrete overdeepenings that indicate occupation by cirque glaciers, and the cirque elevations are relatively uniform from north to south, spanning a distance of roughly 750 km. Such mountain glacier features have been preserved since the start of continental-scale glaciation (>33.9 Myr ago). Preservation results from freezing conditions beneath the ice sheet that have reduced erosion despite active water networks. Reconstructions of temperature indicate 17.1--19.3 +/- 4 at sea level, consistent with sedimentary proxies from the early Eocene (48--58 Myr ago). Here, we compare the Gamburtsevs to other mountain ranges using statistical tests. We focus on comparisons among mountain hypsometries, or the distributions of area with elevation. We introduce two tests, a decay-length test that relates the form of the peaks of the individual ranges and a χ2 goodness-of-fit test for the overall distribution. Results show that there is a striking similarity to mountains that are

  10. Two species of Selaginella cones and their spores from the Bohemian Carboniferous continental basins of the Czech Republic. (United States)

    Bek, J; Oplustil, S; Drábková, J


    Two species of Selaginella cones from the Bohemian Upper Carboniferous continental basins of the Bolsovian and Westphalian D age are described, together with their in situ spores. Two specimens of Selaginella gutbierii yielded microspores closely comparable with the dispersed species Cirratriradites saturnii and megaspores closely comparable with the dispersed species Triangulatisporites vermiculatus. Microspores closely comparable with the dispersed species Cirratriradites annulatus and megaspores resemble the dispersed species Triangulatisporites tertius were isolated from cones of Selaginella cf. leptostachys. All the spores isolated from one cone are of the same type and would be referred to one dispersed micro- and megaspore species if found as Sporae dispersae. The paper contains a review of all palynologically studied Carboniferous Selaginella and Selaginella-like cones and reviews of all in situ and dispersed Cirratriradites and Triangulatisporites spores.

  11. New Paleomagnetic Results and Inclination Correction for the Carboniferous Conemaugh Group rocks, Southwestern Pennsylvania (United States)

    Kodama, K. P.


    In order to check the inclination correction of the Carboniferous Mauch Chunk Formation red beds made by Tan and Kodama [2002], the Carboniferous Buffalo Siltstone and Brush Creek Limestone (Conemaugh Group) from southwestern Pennsylvania were sampled so that an inclination correction could be applied to these magnetite-bearing rocks. Paleopoles from the Buffalo Siltstone (BS) and Brush Creek Limestone (BCL) were previously reported by Payne et al. [1981]. Twenty-eight oriented hand samples were collected from 5 of Payne et al.'s 6 sites, predominately from clastic lithologies. A combination of low temperature thermal demagnetization (up to 200° C) followed by alternating field demagnetization (up to 50 mT) allowed characteristic remanences to be isolated in a majority of the samples. A mean direction for 21 samples from 5 sites of D=170.9° , I=23.4° , K=14.0 yielded an uncorrected paleopole at 36.6° N, 111.1° E, closer to the BCL paleopole (36.1° N, 124.3° E) than the BS paleopole (27.4° N, 123.0° E) of Payne et al. In order to make the inclination correction using the anisotropy of anhysteretic remanence (AAR) of the samples, we estimated the individual particle anisotropy (a), by fitting corrected directions to theoretical correction curves as a function of individual particle anisotropy. The best fit suggests an individual particle anisotropy (a value) of about 1.5 should be used; however, the corrected directions have a strongly elliptical distribution. Assuming that a circular distribution of directions would be closer to that caused by random errors in measurement and orientation, a correction using a=2 was made because it gives both an acceptable fit to the theoretical correction curves and a circular directional distribution. The mean corrected direction of D=173.5° , I=42.0° yields a corrected paleopole at 25° N, 106.5° E which agrees remarkably well with a corrected Mauch Chunk Formation paleopole at 26.3° N, 111.2° E. This corrected Mauch

  12. Approximate western limit of glaciation within the Standing Rock Indian Reservation, Sioux County, North Dakota, and Corson County, South Dakota (United States)

    U.S. Geological Survey, Department of the Interior — This coverage contains information about the western limit of glaciation within the Standing Rock Indian Reservation, Sioux County, North Dakota, and Corson County,...

  13. Extensive MIS 3 glaciation in southernmost Patagonia revealed by cosmogenic nuclide dating of outwash sediments (United States)

    Darvill, Christopher M.; Bentley, Michael J.; Stokes, Chris R.; Hein, Andrew S.; Rodés, Ángel


    The timing and extent of former glacial advances can demonstrate leads and lags during periods of climatic change and their forcing, but this requires robust glacial chronologies. In parts of southernmost Patagonia, dating pre-global Last Glacial Maximum (gLGM) ice limits has proven difficult due to post-deposition processes affecting the build-up of cosmogenic nuclides in moraine boulders. Here we provide ages for the Río Cullen and San Sebastián glacial limits of the former Bahía Inútil-San Sebastián (BI-SSb) ice lobe on Tierra del Fuego (53-54°S), previously hypothesised to represent advances during Marine Isotope Stages (MIS) 12 and 10, respectively. Our approach uses cosmogenic 10Be and 26Al exposure dating, but targets glacial outwash associated with these limits and uses depth-profiles and surface cobble samples, thereby accounting for surface deflation and inheritance. The data reveal that the limits formed more recently than previously thought, giving ages of 45.6 ka (139.9/-14.3) for the Río Cullen, and 30.1 ka (+45.6/-23.1) for the San Sebastián limits. These dates indicate extensive glaciation in southern Patagonia during MIS 3, prior to the well-constrained, but much less extensive MIS 2 (gLGM) limit. This suggests the pattern of ice advances in the region was different to northern Patagonia, with the terrestrial limits relating to the last glacial cycle, rather than progressively less extensive glaciations over hundreds of thousands of years. However, the dates are consistent with MIS 3 glaciation elsewhere in the southern mid-latitudes, and the combination of cooler summers and warmer winters with increased precipitation, may have caused extensive glaciation prior to the gLGM.

  14. Eskers and other evidence of wet-based glaciation in Phlegra Montes, Mars. (United States)

    Gallagher, Colman; Balme, Matt


    Although glacial landsystems produced under warm/wet based conditions are very common on Earth, glaciological and landform evidence indicates that glaciation on Mars during the Amazonian period (3 Ga to present) has been characterised by cold/dry based glaciers, consistent with the prevailing cold, hyperarid conditions. However, this presentation describes a system of sinuous ridges, interpreted as eskers (1), emerging from the degraded piedmont terminus of a Late Amazonian (˜150 Ma) glacier in the southern Phlegra Montes region of Mars. This is probably the first identification of martian eskers that can be directly linked to their parent glacier. Together with their contextual landform assemblage, the eskers are indicative of glacial melting and subglacial meltwater routing but the confinement of the system to a well-defined, regionally significant graben, and the absence of eskers elsewhere in the region, suggests that melting was a response to locally enhanced geothermal heat flux, rather than regional, climate-induced warming. Now, however, new observations reveal the presence of many assemblages of glacial abrasion forms and associated channels that could be evidence of more widespread wet-based glaciation in Phlegra Montes, including the collapse of several distinct ice domes. This landform assemblage has not been described in other glaciated, mid-latitude regions of the martian northern hemisphere. Moreover, Phlegra Montes are flanked by lowlands displaying evidence of extensive volcanism, including contact between plains lava and piedmont glacial ice. These observations suggest that the glaciation of Phlegra Montes might have been strongly conditioned by both volcanism and more restricted forms of ground-heating. These are important new insights both to the forcing of glacial dynamic and melting behaviour on Mars by factors other than climate and to the production of liquid water on Mars during the Late Amazonian. (1) Gallagher, C. and Balme, M. (2015

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

    Petter Sejrup, Hans; Oline Hjelstuen, Berit


    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.

  16. Pattern of Holocene glaciation in the monsoon-dominated Kosa Valley, central Himalaya, Uttarakhand, India (United States)

    Bisht, Pinkey; Nawaz Ali, S.; Rana, Naresh; Singh, Sunil; Poonam; Sundriyal, Y. P.; Bagri, D. S.; Juyal, Navin


    Reconstruction based on the geomorphology, lateral moraine stratigraphy, and limited optical chronology indicate that the monsoon-dominated Kosa Valley experienced four glacial advances during the late glacial to late Holocene. The oldest and most extensive glaciation, which is termed as Raj Bank Stage-1 (RBS-1), is represented by the degraded moraine ridge. This glaciation remains undated; however, the chronology of outwash terrace gravel dated to 12.7 ± 1.3 ka indicates that the RBS-1 probably represents the Last Glacial Maximum (LGM). The second glacial advance (RBS-2) is preserved as a curvilinear lateral moraine and is dated to 6.1 ± 0.4 ka. The third glacial advance viz. RBS-3 is bracketed between 5.0 ± 0.5 and 4.0 ± 0.4 ka. Following this, the glacier receded in pulses that are represented by two distinct recessional moraines (RBS-3a and b). The forth glacial stage (RBS-4), which is dated between 2.2 ± 0.2 and 1.6 ± 0.2 ka, shows a pulsating recession and is represented by a prominent recessional moraine (RBS-4a). Whereas, presence of unconsolidated, poorly defined moraine mounds proximal to the glacier snout are ascribed as neoglacial advance corresponding to the Little Ice Age (LIA). With the limited chronometric data, we speculated that the glaciation was driven during the weak to moderate Indian Summer Monsoon (ISM) aided by lowered temperature. Presence of recessional moraines associated with mid-Holocene glacial phase indicate that the monsoon-dominated glaciers respond sensitively to minor (sub-millennial scale) changes in temperature and precipitation conditions. The observations are broadly in accordance with the studies carried out in other monsoon-dominated valleys in the central Himalaya, implying that in ISM dominated regions, lowered temperature seems to be the major driver of glaciations during the late glacial to late Holocene.

  17. A Devonian to Carboniferous intra-oceanic subduction system in Western Junggar, NW China (United States)

    Zhang, Ji'en; Xiao, Wenjiao; Han, Chunming; Mao, Qigui; Ao, Songjian; Guo, Qianqian; Ma, Chong


    The Devonian and Carboniferous rock assemblages in Western Junggar, southern Altaids, include ophiolitic mélanges and coherent units. At Baijiantan, Yeyagou and Dagun Devonian gabbros and one group of volcanic rocks (type I lava) generally crop out as blocks in a matrix of ultramafic rocks and/or mudstone. They have a depleted light rare earth element (LREE) and mid-oceanic ridge basalt (MORB)-like signature with a small negative Nb anomaly, suggesting formation in a back-arc basin. Another group of volcanic rocks (type II lava) from Baijiantan, Yeyagou, Western Karamay and Maliya includes alkaline basalt, basanite, andesite, dacite and trachyte that contain microphenocrysts of clinopyroxene-plagioclase, amygdales filled with chalcedony and calcite, and accessory pyrite and ilmenite. The type II lavas are further subdivided into five sub-types: (1) Type II1 lava is strongly enriched in LREE with incompatible trace element ratios similar to oceanic island basalt (OIB), suggesting derivation from enriched mantle. (2) Type II2 lava and tuff are slightly LREE-enriched, with a marked negative Nb anomaly and Th/Yb-enrichment indicating that they were generated in a supra-subduction zone (SSZ). (3) Type II3 lava is also moderately enriched in LREE suggesting derivation from a more-enriched MORB mantle. (4) Type II4 lava is enriched in LREE and has high Nb/Yb values close to those of OIB. It is extensively depleted in Nb suggesting a source containing a mixture of enriched and SSZ mantle. (5) Type II5 lava has MORB-like REE patterns, and Nb/Yb and Th/Yb ratios. Based on field structural data, and the contemporaneity of the Baogutu adakite, a high-Mg diorite dike and the Miaoergou charnockite, these enriched and depleted magmatic features suggest generation in an intra-oceanic subduction zone influenced by ridge-trench interaction. The Altaids in Western Junggar are characterized by multiple intra-oceanic subduction systems, which may have continued to operate to the late

  18. Permo-Carboniferous granitoids with Jurassic high temperature metamorphism in Central Pontides, Northern Turkey (United States)

    Gücer, Mehmet Ali; Arslan, Mehmet; Sherlock, Sarah; Heaman, Larry M.


    In the northern part of the Central Pontides (N Turkey) there are different metamorphic rocks exposed, notably the Devrekani metamorphic rocks. Here, upper amphibolite-lower granulite facies metamorphic rocks contain predominantly paragneiss, orthogneiss and metacarbonate, and to a lesser extent, amphibolite and quartzite, with cross-cutting aplite, pegmatite and granite veins. This is the first report of these rocks and includes new data on the petrochemistry, geochronology and metamorphic evolution of the Devrekani orthogneisses from the Central Pontides. The orthogneisses show five different mineral parageneses with the characteristic mineral assemblage quartz + K-feldspar + plagioclase + biotite ± hornblende ± opaque (± ilmenite and ± magnetite), and accessory minerals (zircon, sphene and apatite). These metamorphic rocks exhibit generally granoblastic, lepidogranoblastic and nematolepidogranoblastic with locally migmatitic and relic micrographic textures. They have well-developed centimeter-spaced gneissic banding and display gneissose structure with symmetric, asymmetric and irregular folds. The petrographic features, mineralogical assemblages and weak migmatization reflect high temperature conditions. Thermometric calculations in the orthogneisses indicate metamorphic temperatures reached 744 ± 33 °C. Field relations, petrography and petrochemistry suggest that the orthogneisses have predominantly granodioritic and some granitic protoliths, that show features of I-type, medium to high-potassic calc-alkaline volcanic arc granitoids. The orthogneisses have high contents of LILEs and low contents of HFSEs with negative Nb and Ti anomalies, which are typical of subduction-related magmas. The orthogneisses also show significant LREE enrichment relative to HREE with negative Eu anomalies (EuN/Eu* = 0.33-1.07) with LaN/LuN = 6.98-20.47 values. Based on U-Pb zircon dating data, the protoliths are related to Permo-Carboniferous (316-252 Ma) magmatism. It is

  19. Climate instability in the Yili region,Xinjiang during the last glaciation

    Institute of Scientific and Technical Information of China (English)


    The climate is influenced by westerlies year in year out and the aeolian loess is widespread in the Yili region,the Xinjiang Uygur Autonomous Region. Through the study of the loess section with a thickness of 21.5 m,much useful information about climatic change in this region during the last glaciation was gotten. Grain size analysis of loess samples in the section showed that the climatic change in the Yili region was of instability during the last glaciation and similar to those of the North Atlantic Ocean and Greenland. In correspondence with the Heinrich events,the percentage of the size fraction of loess with grain size less than 10 mm decreased in cold stadials in the Yili region. This result suggests that the westerly wind be strengthened during the cold periods. Compared with the stadials,the content of the loess with grain size less than 10 mm was increased in interstadials,which indicated that the strength of the westerly wind was weakened. It is obvious that the climate was instable not only in the North Atlantic Ocean and polar regions,but also in other areas of Northern Hemisphere during the last glaciation.

  20. Palynostratigraphy of the Zorritas Formation, Antofagasta region, Chile: Insights on the Devonian/Carboniferous boundary in western Gondwana

    Directory of Open Access Journals (Sweden)

    Claudia V. Rubinstein


    Full Text Available The Middle Member of the Zorritas Formation in the Antofagasta region of northern Chile, yielded terrestrial and marine palynomorph assemblages which span the Devonian/Carboniferous boundary. The assemblages show a clear predominance of terrestrial palynomorphs with 70 miospore species, 18 marine phytoplankton species, two non-marine algae and one chitinozoan species, all coming from 15 productive levels. Palynomorphs are poorly preserved and most of them are reworked. Three palynological associations are recognized based on miospores. These are assigned to the Tournaisian–Visean, Tournaisian and probable latest Famennian. Age assignments are discussed in the frame of the spore zonal schemes established for Euramerica and western Gondwana. The stratigraphical distribution of spores allows the identification of the probable position of the Devonian/Carboniferous boundary within the Zorritas Formation. This system boundary is proposed for the first time in Palaeozoic sedimentary rocks of northern Chile. The presence of Gondwanan typical miospore species indicates affinities with this palaeocontinent even though the Tournaisian and Tournaisian–Visean miospore associations support the cosmopolitanism already suggested for the early Carboniferous flora. The significant number of reworked palynomorphs together with the sedimentological analysis of the studied sections, suggest that these deposits were severely impacted by the climatic change and major sea level fluctuations. Similar conditions were recorded in coeval western Gondwana basins.

  1. Tyloses and ecophysiology of the early carboniferous progymnosperm tree Protopitys buchiana. (United States)

    Scheckler, Stephen E; Galtier, Jean


    Trunk woods of Early Carboniferous Protopitys buchiana show the earliest example of tylose formation and the first record for a progymnosperm. Protopitys tyloses are more densely located in inner trunk woods and near growth layer boundaries. We suggest, therefore, that an altered physiological state of living ray cells, during dormancy and/or following water stress, was necessary to make the woods vulnerable to tylose formation. Coupled with the distribution and proximity of abundant wood ray parenchyma to large xylem conducting cells, the positions of conduits filled with tyloses can be interpreted as ecophysiological responses of the plant to changes in local environment. In addition, some xylem conducting cells might have functioned as vessels. Fungal hyphae are present in some tracheary cells and in some areas with tyloses, but there is no evidence for wood trauma; we conclude, therefore, that these particular cases of tyloses are probably not induced by wound trauma. Protopitys buchiana wood thus shows structure/function similarities to modern woods with vessels, such as those of dicot angiosperms. This implies that ancient and modern plant ecophysiological responses correlate well with the physical parameters of their cellular construction.

  2. In situ ion microprobe U-Pb dating and REE abundances of a carboniferous conodont (United States)

    Sano, Yuji; Terada, Kentaro

    We report here in situ ion microprobe U-Pb dating of a conodont micro-fossil using an ion microprobe method. Thirteen spots on the single fragment of the Carboniferous conodont (size: approximately 800 µm × 100 µm) yield a 238U/206Pb isochron age of 323±36 Ma and a Tera-Wasserburg concordia intercept age of 332±44 Ma in a three-dimensional 238U/206Pb-207Pb/206 Pb-204Pb/206Pb diagram. These ages are consistent with the depositional and early diagenetic ages of the fossil in its host Mississippian sedimentary sequence within experimental error. The success of the method depends on the chemical fractionation of U from Pb within a hundred-µm length scale and the consequent variations in Pb isotopic compositions due to radioactive decay. Shale-normalized rare earth element (REE) abundances of two spots on the same sample show flat patterns from light REE to middle REE and decreases from middle REE to heavy REE with negative anomalies of both Ce and Eu. The REE characteristics are significantly different from those of Devonian conodonts reported by other workers, suggesting discrepant redox states and/or formation environments.

  3. Paleomagnetism of the Upper Carboniferous and Upper Permian sedimentary rocks from Novaya Zemlya Archipelago (United States)

    Abashev, Victor V.; Mikhaltsov, Nikolay E.; Vernikovsky, Valery A.; Metelkin, Dmitry V.; Matushkin, Nikolay Yu.; Doubrovine, Pavel V.


    Here we present the first paleomagnetic directions and paleomagnetic poles for Upper Permian and Upper Carboniferous sedimentary rocks (sandstones and limestones) of the Novaya Zemlya Archipelago in the Russian High Arctic region. The paleomagnetic directions were obtained through detailed thermal and alternating field demagnetization experiments, using the principal component analysis of demagnetization data. A positive fold test and a positive reversal test indicate that the isolated paleomagnetic directions correspond to the primary magnetization components. Magnetic remanence carriers were characterized through rock-magnetic analyses, including measurements of temperature dependence of low-field magnetic susceptibility, magnetic hysteresis curves, and first-order reversal curves (FORC). We will describe the rock-magnetic properties of different lithological units and discuss their implications for the stability of natural remanent magnetization (NRM) and the veracity of paleomagnetic record. The tectonics implications of the new paleomagnetic data for the evolution of the Barents-Kara continental margin and the Novaya Zemlya Archipelago will be also discussed. The paleomagnetic poles differ slightly from the corresponding section of the APWP for Baltica, which is probably due to inclination shallowing effect or the tectonic features of the region. The study was supported by Russian Science Foundation grant 14-37-00030, the SIU project HNPla-2013/10049 (HEAT) and by Ministry of Education and Science of the Russian Federation grant 5.515.2014/K.

  4. Paleoenvironmental changes recorded on UPPer Carboniferous reef in Guangxi,China

    Institute of Scientific and Technical Information of China (English)

    GONG EnPu; CHEN Xiaohong; ZHANG Yongli; GUAN Changqing; CHANG Honglun; HONG Guang


    Based on detailed measurement in the field and a comPrehensive analysis of carbonate microfacies, the Pennsylvanian reefal microfacies characteristic and sedimentary environment from Longjiangdong,Guangxi, China are analyzed. The twelve carbonate microfacies have been recognized including micritic/microsParitic limestone,Peloidal/aggregate-grain grainstone,bioclastic wackestone/Packstone,laminated mudstone,bounds-tone,bioclastic wackestone/Packstone with single shell,coral framestone/bafflestone,bioclastic Packstones/grainstones with abundant benthic foraminifera or crinoids,wackestone/mudstone with calcisPheres,bioclastic Packstone/grainstone,unname reef-building organism framestone and brachioPod grainstone. In addition,four facies have been identified including oPen Platform facies,restricted Platform facies,coral reefal facies and shoal facies. According to analysis of microfacies combination and facies evolution,three stages and three reef units during the reef formation Process have been noted. The evolution of each stage indicates a rePeating fluctu-ation of the sea-level,but the water energy is still relatively low overall,which rePresents frequent changes of Paleoclimate in the early Late Carboniferous.

  5. 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.


    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.

  6. Single well multidisciplinary facies reconstruction (De Lute-6 Upper Carboniferous, Netherlands)

    Energy Technology Data Exchange (ETDEWEB)

    Van Der Zwan, C.J. (Nederlandse Aardolie Maatschappij B.V., Assen (Netherlands)); Van De Laar, J.G.M.; Pagnier, H.J.M.; Van Amerom, H.W.J. (Geological Survey of the Netherlands, Heerlen (Netherlands))


    De Lutte-6 is a key well situated in onshore Netherlands. A cored lithological sequence from the Upper Carboniferous has been investigated by means of palynology, palynofacies, paleobotany, and sedimentology. Paleobotanical data suggest a late Westphalian C to late Westphalian D Age. Palynological assemblages have a late Westphalian D-Stephanian character. This discrepancy suggests that the local paleobotanical remains allow for a more precise age determination, whereas the palynological data provide information about the regional facies development. Palynofacies analyses combined with palynoflora data indicate a gradual transition from a waterlogged flood plain characterized by a diverse lycopod/cordait palynoflora, to well-drained flood plain with an impoverished cordait/conifer palynoflora. The sedimentological data, combined with the palynological and the paleobotanical data, suggest that the flood plains alternate with swamp and lake deposits. The transition from a waterlogged flood plain to a well-drained flood plain coincides with transition from intervals characterized by seat-earth soils (indicating humid conditions) to intervals characterized by immature calcie soils (witnessing semihumid to semi-arid conditions).

  7. 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.


    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.

  8. Synthetic analysis of the Neuropterids - their interest for the decipherment of Carboniferous palaeogeography

    Energy Technology Data Exchange (ETDEWEB)

    Laveine, J.P. [Universitaire de Science et Technologie de Lille, Villeneuve d`Ascq (France). Lab. Paleobotanique


    `Neuropterids` are of the dominant groups of Carboniferous fossil-plants. The original definition of Nevropteris, initially given as a section of the genus Filicites, was based only on the shape, the mode of attachment to the rachis, and the venation of the pinnules. Subsequent information has shown that the originally defined taxon, in fact, comprises many genera belonging to several distinct families of Pteridosperms, which are distinguished on various features of frond architecture, male and female reproductive organs and apparatuses, anatom, and morphology and venation of the pinnules. Unfortunately, these characteristics are not equally known within each group, even at a general level, and are not always available through usual palaeobotanical collecting. However, it is essential to reach the most precise, `natural` level of taxonomy for the decipherment of the many interrelated problems raised by palaeobotanical studies, i.e. evolution, biostratigraphy, palaeobiogeography, palaeoecology and, as a feedback consequence, systematics. Despite restricting the analysis mainly to the external morphological characters, the `Neuropterids` provide a fine example of such interrelated fundamental questions.

  9. Origin and accumulation mechanisms of petroleum in the Carboniferous volcanic rocks of the Kebai Fault zone, Western Junggar Basin, China (United States)

    Chen, Zhonghong; Zha, Ming; Liu, Keyu; Zhang, Yueqian; Yang, Disheng; Tang, Yong; Wu, Kongyou; Chen, Yong


    The Kebai Fault zone of the West Junggar Basin in northwestern China is a unique region to gain insights on the formation of large-scale petroleum reservoirs in volcanic rocks of the western Central Asian Orogenic Belt. Carboniferous volcanic rocks are widespread in the Kebai Fault zone and consist of basalt, basaltic andesite, andesite, tuff, volcanic breccia, sandy conglomerate and metamorphic rocks. The volcanic oil reservoirs are characterized by multiple sources and multi-stage charge and filling history, characteristic of a complex petroleum system. Geochemical analysis of the reservoir oil, hydrocarbon inclusions and source rocks associated with these volcanic rocks was conducted to better constrain the oil source, the petroleum filling history, and the dominant mechanisms controlling the petroleum accumulation. Reservoir oil geochemistry indicates that the oil contained in the Carboniferous volcanic rocks of the Kebai Fault zone is a mixture. The oil is primarily derived from the source rock of the Permian Fengcheng Formation (P1f), and secondarily from the Permian Lower Wuerhe Formation (P2w). Compared with the P2w source rock, P1f exhibits lower values of C19 TT/C23 TT, C19+20TT/ΣTT, Ts/(Ts + Tm) and ααα-20R sterane C27/C28 ratios but higher values of TT C23/C21, HHI, gammacerane/αβ C30 hopane, hopane (20S) C34/C33, C29ββ/(ββ + αα), and C29 20S/(20S + 20R) ratios. Three major stages of oil charge occurred in the Carboniferous, in the Middle Triassic, Late Triassic to Early Jurassic, and in the Middle Jurassic to Late Jurassic periods, respectively. Most of the oil charged during the first stage was lost, while moderately and highly mature oils were generated and accumulated during the second and third stages. Oil migration and accumulation in the large-scale stratigraphic reservoir was primarily controlled by the top Carboniferous unconformity with better porosity and high oil enrichment developed near the unconformity. Secondary dissolution

  10. Pleistocene glaciations in the weatern Arctic Ocean: Tentative age model of marine glacial landforms (United States)

    Niessen, Frank; Stein, Rüdiger; Matthiessen, Jens; Jensen, Laura; Nam, Seung-Il; Schreck, Michael


    Recently glacial landforms were presented and interpreted as complex pattern of Pleistocene glaciations in the western Arctic Ocean along the continental margin of the East Siberian and Chukchi seas, (Niessen et al. 2013, Dove et al. 2014). These landforms include moraines, drumlins, glacigenic debris flows, till wedges and mega-scale glacial lineations. Orientations of some of the landforms suggest the presence of former ice sheets on the Chukchi Borderland and the East Siberian shelf. Here we present a tentative age model for some of the younger glacial events by correlation of sediment cores with glacial landforms as seen in subbottom profiles. The database was obtained during RV "Polarstern" cruise ARK-XIII/3 (2008) and RV "Araon" cruise ARA03B (2012), which investigated an area between the Chukchi Borderland and the East Siberian Sea between 165°W and 170°E. The stratigraphic correlation of sediment cores is based on physical properties (wet-bulk density and magnetic susceptibility), lithology and color. The chronology of the area has been proposed by Stein et al. (2010) for a core from the Chukchi Abyssal Plain (PS72/340-5) and includes brown layers B1 to B9 (marine isotope stages MIS 1 to MIS 7), which are used as marker horizons for lateral core correlation. Our tentative age model suggests that the youngest and shallowest (480 m below present water level; mbpwl) grounding event of an ice sheet on the Chukchi Borderland is younger than B2 (interpreted as Last Glacial Maximum; LGM). There is no clear evidence for a LGM glaciation along the East Siberian margin because intensive post LGM iceberg scouring occurred above 350 m present water level. On the slopes of the East Siberian Sea two northerly directed ice advances occurred, both of which are older and younger than B2 and B3, respectively. The younger advance grounded to about 700 m present water depth along the continental slope and the older to 900 m and 1100 m on the Arlis Plateau and the East

  11. Mountain Plover [ds109 (United States)

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

  12. Unravelling genetics at the top: mountain islands or isolated belts? (United States)

    García-Fernández, Alfredo; Segarra-Moragues, Jose Gabriel; Widmer, Alex; Escudero, Adrian; Iriondo, José María


    Background and Aims In mountain plant populations, local adaptation has been described as one of the main responses to climate warming, allowing plants to persist under stressful conditions. This is especially the case for marginal populations at their lowest elevation, as they are highly vulnerable. Adequate levels of genetic diversity are required for selection to take place, while high levels of altitudinal gene flow are seen as a major limiting factor potentially precluding local adaptation processes. Thus, a compromise between genetic diversity and gene flow seems necessary to guarantee persistence under oncoming conditions. It is therefore critical to determine if gene flow occurs preferentially between mountains at similar altitudinal belts, promoting local adaptation at the lowest populations, or conversely along altitude within each mountain. Methods Microsatellite markers were used to unravel genetic diversity and population structure, inbreeding and gene flow of populations at two nearby altitudinal gradients of Silene ciliata, a Mediterranean high-mountain cushion plant. Key Results Genetic diversity and inbreeding coefficients were similar in all populations. Substantial gene flow was found both along altitudinal gradients and horizontally within each elevation belt, although greater values were obtained along altitudinal gradients. Gene flow may be responsible for the homogeneous levels of genetic diversity found among populations. Bayesian cluster analyses also suggested that shifts along altitudinal gradients are the most plausible scenario. Conclusions Past population shifts associated with glaciations and interglacial periods in temperate mountains may partially explain current distributions of genetic diversity and population structure. In spite of the predominance of gene flow along the altitudinal gradients, local genetic differentiation of one of the lower populations together with the detection of one outlier locus might support the existence

  13. A conceptual glacio-hydrological model for high mountainous catchments

    Directory of Open Access Journals (Sweden)

    B. Schaefli


    Full Text Available In high mountainous catchments, the spatial precipitation and therefore the overall water balance is generally difficult to estimate. The present paper describes the structure and calibration of a semi-lumped conceptual glacio-hydrological model for the joint simulation of daily discharge and annual glacier mass balance that represents a better integrator of the water balance. The model has been developed for climate change impact studies and has therefore a parsimonious structure; it requires three input times series – precipitation, temperature and potential evapotranspiration – and has 7 parameters to calibrate. A multi-signal approach considering daily discharge and – if available – annual glacier mass balance has been developed for the calibration of these parameters. The model has been calibrated for three different catchments in the Swiss Alps having glaciation rates between 37% and 52%. It simulates well the observed daily discharge, the hydrological regime and some basic glaciological features, such as the annual mass balance.

  14. 末次冰期东亚冰川规模与冰川进退异时性问题%The glacial extent and glacial advance/retreat asynchroncity in East Asia during Last Glaciation

    Institute of Scientific and Technical Information of China (English)

    张威; 崔之久; 李永化


    New dates for last glacial cycle in Tibetan bordering mountains and in East Asia show the glacial extent during the early/middle (MIS3-4) stage is larger than that of the late stage (MIS2) in last glacial cycle. It is asynchronous with the Northern Hemisphere ice sheets maximum and changes in oceanic circulation that predominately control global climate. In research areas, three seasonal precipitation patterns control the accumulation and ablation of glaciers. The modes of the westerlies and the East Asian mountains/islands in and along the Pacific Ocean are favorable to glacier advance with mainly winter precipitation accumulation. There was a global temperature-decreasing phase in the middle stage (MIS3b, 54-44 ka BP), when the glacier extent was larger than that in Last Glaciation Maximum due to the low temperature combined with high moisture. It is revealed that the Quaternary glaciers not only evolved with localization, but also maybe with globalization. The latest studies show a fact that the developmental characteristics of glaciers in high mountains or islands along the western Pacific Ocean are not in accord with those inland areas. Therefore, it can be concluded that glacier development exhibits regional differences. The study validates the reasonableness of the asynchronous advance theory, and ascertains that both the synchronous and asynchronous advance/retreat of glaciers existed from 30 ka BP to 10 ka BP. It is not suitable to emphasize the synchronicity between global ice-volume and glacier change.

  15. Mountains, glaciers, and mines—The geological story of the Blue River valley, Colorado, and its surrounding mountains (United States)

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


    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.

  16. Glacial geomorphology of the Torres del Paine region (southern Patagonia): Implications for glaciation, deglaciation and paleolake history (United States)

    García, Juan-Luis; Hall, Brenda L.; Kaplan, Michael R.; Vega, Rodrigo M.; Strelin, Jorge A.


    The processes affecting paleoclimate variability and Pleistocene glacial landscape development in the southern mid-latitudes remain poorly understood, in part because of the scarcity of comprehensive, well-studied records. Glacial landforms are invaluable for reconstructing past ice-sheet, climate, and associated environmental changes along the southern Andes, but there are significant spatial and temporal gaps in existing data. In this paper, we present new geomorphic and sedimentologic analyses, including surficial maps, for the Torres del Paine region (51°S, 73°W), southern South America. Our findings provide a new framework for understanding changes in the regional glacier history and Pleistocene landscape development. Glacial extent during the local last glacial maximum (LGM) remains unknown but new chronological data supported by geomorphic evidence afford evidence for a larger ice sheet at Torres del Paine than previously assumed. Deglaciation from the local LGM was underway by 17,400 ± 200 (1σ) cal. yr. BP. As opposed to previous suggestions, we have found that most of the moraines fringing the lakes in the Torres del Paine national park were deposited during a late-glacial expansion that occurred between 14,100 and 12,500 cal. yr. BP. Late-glacial advances also have been documented recently for the Última Esperanza and Lago Argentino basins to the south and north of Torres del Paine, respectively, suggesting an overall regional ice response to a climate signal. The Tehuelche paleolake accompanied each of the ice-sheet fluctuations in Torres del Paine. New data document at least three main phases of this paleolake, which drained eastward to the Atlantic Ocean, while the Andes gaps were blocked with ice. During the late phase of glacial lake formation, when water levels reached 125-155 m a.s.l., the lake likely merged with paleolake Consuelo in the Última Esperanza area at the end of the last glaciation. Lake Tehuelche in Torres del Paine had drained

  17. Glacial morphology and debris-covered glaciers of northeast of Bolkar Mountains

    Directory of Open Access Journals (Sweden)

    Onur Çalışkan


    Full Text Available In this research the glaciers and glaciated areas of northwest of Bolkar mountains and their geographical conditions have been studied. Recent debris-covered glaciers have been determined in the higher (>2900 m parts of north and, partially, northeast-facing cirques of two glaciated areas of Pleistocene. The surface area of the largest glacier (Medetsiz of seven glaciers in Karagöl and Alişan Glaciated Areas is 0,23 km2. On the other hand, Eğerkaya East Glacier occupies a confined place of 0,09 km2. While all the glaciers display the evidence of glacial karst, the Kopukgöl Glacier has exceptionally three supraglacial lakes. In the light of previous data, it is concluded there have been no notable regression in the terminal of the glaciers that since last 60 years. Due to the presence of a debris cover over the glaciers that hampers supraglacially melting, it is possible to suggest that englacial and subglacial ablation should be accounted for of the ablation of glaciers.

  18. Carbonate petrology of algal limestones (Lois-Ciguera Formation, Upper Carboniferous, León, Spain)

    NARCIS (Netherlands)

    Meijer, de J.J.


    The Lois-Ciguera Formation is a unit of alternating limestones and terrigenous sediments of Lower to Upper Moscovian age in the Cantabrian Mountains of northern Spain. The proportion of limestones is fairly high, 30 to 50% of the total thickness. In the eastern part of the Lois-Ciguera Synclinorium,

  19. Mountain Pine Beetle (United States)

    Gene D. Amman; Mark D. McGregor; Robert E. Jr. Dolph


    The mountain pine beetle, Dendroctonus ponderosae Hopkins, is a member of a group of beetles known as bark beetles: Except when adults emerge and attack new trees, the mountain pine beetle completes its life cycle under the bark. The beetle attacks and kills lodgepole, ponderosa, sugar, and western white pines. Outbreaks frequently develop in lodgepole pine stands that...

  20. Mountain chickadee (Poecile gambeli) (United States)

    McCallum, D. Archibald; Grundel, Ralph; Dahlsten, Donald L.; Poole, Alan; Gill, Frank


    The Mountain Chickadee (Poecile gambeli), a small, cavity-nesting songbird, is one of the most common birds of montane and coniferous forest from southern Arizona and Baja California north to British Columbia and the Yukon territory. This publication describes the life history of the Mountain Chickadee.

  1. Tonganoxichnus, a new insect trace from the Upper Carboniferous of eastern Kansas (United States)

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


    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

  2. Geochemistry and provenance of the Carboniferous Baixo Alentejo Flysch Group, South Portuguese Zone (United States)

    Jorge, R. C. G. S.; Fernandes, P.; Rodrigues, B.; Pereira, Z.; Oliveira, J. T.


    This work is focused on the turbiditic sediments from the Carboniferous Baixo Alentejo Flysch Group (BAFG) in the South Portuguese Zone, an external zone of the Iberian Variscides. The aim of this work is to constrain the provenance and tectonic setting of these sediments in a context of a complex evolution of SW Iberian Variscides. For this purpose, we performed a systematic study of petrographical and geochemical signatures of greywackes and shales from the three BAFG formations: Mértola, Mira and Brejeira. Major and trace element composition and ratios suggest heterogeneous source area composition for BAFG shales and greywackes. For the oldest Mértola Formation greywackes, source area is dominated by granitoid rocks with minor mafic input. The latter becomes residual in the Mira Formation. The youngest Brejeira Formation greywackes show clear felsic affiliation associated with an increase in recycled components. The shales of all three BAFG formations denote a granodioritic affiliation. Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) values suggest moderate weathering in the source areas of Mértola and Mira formations. These indices, together with A-CN-K relations, point out to steady-state weathering conditions in the source areas of both formations. In contrast, both CIA and PIA values for the Brejeira Formation indicate variable conditions of palaeoweathering, from moderate to intense, as a consequence of non-steady-state conditions probably triggered by tectonic instability in the provenance area. Compared to the greywackes, the shales of all three BAFG formations exhibit higher CIA and PIA values, as well as low K2O/Al2O3 (~ 0.2) and index of compositional variability (Morena Zone (Gondwanan affinity), with possible contribution from an external (Avalonian) source.

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

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


    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

  4. An East Siberian ice shelf during the Late Pleistocene glaciations: Numerical reconstructions (United States)

    Colleoni, Florence; Kirchner, Nina; Niessen, Frank; Quiquet, Aurélien; Liakka, Johan


    A recent data campaign in the East Siberian Sea has revealed evidence of grounded and floating ice dynamics in regions of up to 1000 m water depth, and which are attributed to glaciations older than the Last Glacial Maximum (21 kyrs BP). The main hypothesis based on this evidence is that a small ice cap developed over Beringia and expanded over the East Siberian continental margin during some of the Late Pleistocene glaciations. Other similar evidence of ice dynamics that have been previously collected on the shallow continental shelves of the Arctic Ocean have been attributed to the penultimate glaciation, i.e. Marine Isotopes Stage 6 (≈140 kyrs BP). We use an ice sheet model, forced by two previously simulated MIS 6 glacial maximum climates, to carry out a series of sensitivity experiments testing the impact of dynamics and mass-balance related parameters on the geometry of the East Siberian ice cap and ice shelf. Results show that the ice cap developing over Beringia connects to the Eurasian ice sheet in all simulations and that its volume ranges between 6 and 14 m SLE, depending on the climate forcing. This ice cap generates an ice shelf of dimensions comparable with or larger than the present-day Ross ice shelf in West Antarctica. Although the ice shelf extent strongly depends on the ice flux through the grounding line, it is particularly sensitive to the choice of the calving and basal melting parameters. Finally, inhibiting a merging of the Beringia ice cap with the Eurasian ice sheet affects the expansion of the ice shelf only in the simulations where the ice cap fluxes are not large enough to compensate for the fluxes coming from the Eurasian ice sheet.

  5. Late Quaternary glaciation history of northernmost Greenland - Evidence of shelf-based ice

    DEFF Research Database (Denmark)

    Larsen, Nicolaj; Kjær, Kurt H.; Funder, Svend Visby;


    to retreat ca 16 ka to 10.3 cal ka BP before the final break-up, which took place ca 10.1 cal ka BP probably as a combined result of increased inflow of warm Atlantic water through the Fram Strait, a shallower halocline and higher summer temperatures, corresponding to orbital maximum solar insolation...... at this time. The existence of extensive shelf-based ice north of Greenland provides an important contribution to the understanding of the LGM glaciation history of the Arctic Ocean....

  6. New Lithostratigraphic Unit Records an Ediacaran Glaciation in Mato Grosso State, Brazil: Serra Azul Formation

    Directory of Open Access Journals (Sweden)

    Francisco Egídio Cavalcante Pinho


    Full Text Available A new succession of diamictites and siltstones was found above post-Marinoan carbonates from the Araras Group in the northern Paraguay Belt (Brazil, in discontinuous outcrops. This new stratigraphic unit, named Serra Azul Formation in this work, has a variable thickness reaching up to 300 meters. The diamictites were deposited in the first 70 m and present glacial evidences, while the siltstones represent the upper part of the succession and show some sandstone layers towards the top of the succession. This glacial record is the youngest Neoproterozoic glacial event that has been found on South America and probably is related to Gaskiers Glaciation (582 Ma.

  7. Devonian and carboniferous arcs of the oyu tolgoi porphyry Cu-Au district, South Gobi region, Mongolia (United States)

    Wainwright, A.J.; Tosdal, R.M.; Forster, C.N.; Kirwin, D.J.; Lewis, P.D.; Wooden, J.L.


    The Central Asian orogenic belt consists of microcontinental blocks and mobile belts positioned between the Siberian craton and the Tarim and North China cratons. Extending across Asia for 5000 km, the belt consists of terranes that decrease in age southward away from the Siberian craton. A time-stratigraphic-structural sequence for the rocks is critical to defining the tectonic evolution of the belt. In the Oyu Tolgoi area of the South Gobi Desert (Mongolia), Devonian and Carboniferous rocks record the construction of multiple arcs, formation of a giant porphyry Cu-Au system, exhumation, and polyphase deformation. The oldest rocks are basaltic volcanic and subvolcanic rocks of the Devonian Alagbayan Group intruded by Late Devonian quartz monzodiorite stocks and dikes, which host giant porphyry Cu-Au deposits. The rocks were exhumed, overlain by pyroclastic rocks, and then tectonically buried by marine mafic supracrustal rocks prior to the youngest Devonian granodiorite intrusions. The postmineral Carboniferous Gurvankharaat Group unconformably overlying the deformed terrane consists of effusive, pyroclastic, subvolcanic and volcaniclastic rocks, as well as sedimentary units. The supracrustal rocks underwent polyphase shortening after 330 Ma and prior to 290 Ma. Variations in stratigraphic sequences suggest that the region is underlain by a submarine arc that became emergent during the Upper Devonian and remained subaerial to shallow subaqueous through much of the Carboniferous. Xenocrystic zircons in igneous rocks suggest that the offshore arcs were sufficiently close to ancient crust to have interacted with detritus shed into marine basins, most likely from the Siberian craton and fringing early Paleozoic terranes. ?? 2011 Geological Society of America.

  8. Sedimentary records of black carbon in the sea area of the Nansha Islands since the last glaciation

    Institute of Scientific and Technical Information of China (English)


    Core 17962 taken from the sea area of the Nansha Islands recorded a sedimentary history of more than 30 000 years. The black carbon data from the core, which can inform us of the history of vegetation fires, show that during the last glaciation, especially during the last glacial maximum at about 18 kaBP, the fluctuation of the concentration and accumulation rate of the black carbon was relatively great, whereas it was small during the Holocene. The isotope composition of the black carbon indicates that the precursors of black carbon were mainly grasses from the last glaciation to the Holocene. The sub-alpine and alpine vegetation zones covered mainly with grass and bush on the lands around the southern South China Sea were probably the sources of black carbon. The altitudinal vegetation changes from the last glaciation to the Holocene gave rise to the changes of the sedimentary characteristics of black carbon.

  9. Antarctic glaciation caused ocean circulation changes at the Eocene-Oligocene transition. (United States)

    Goldner, A; Herold, N; Huber, M


    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.

  10. Modelling of reactive transport in a sedimentary basin affected by a glaciation/deglaciation event

    Energy Technology Data Exchange (ETDEWEB)

    Bea, S.A.; Mayer, U. [Univ. of British Columbia, Dept. of Earth and Ocean Sciences, Vancouver, BC (Canada); MacQuarrie, K.T.B. [Univ. of New Brunswick, Dept. of Civil Engineering, Fredericton, NB (Canada)


    Canada's plan for the long-term care of used nuclear fuel is containment and isolation in a Deep Geologic Repository (DGR) constructed in a suitable sedimentary or crystalline rock formation. In sedimentary basins fluid migration and geochemical conditions may be impacted by multiple interacting processes including density-dependent groundwater flow, solute transport, heat transfer, mechanical loading, and rock-water interactions. Understanding the interactions among these processes is important when assessing the long-term hydrodynamic and geochemical stability of sedimentary basins during glaciation/deglaciation events. To improve the capability to investigate these processes, an enhanced version of the reactive transport code MIN3P (i.e. MIN3P-NWMO) was developed and tested. The processes incorporated in the new model were evaluated by simulating reactive transport in a hypothetical sedimentary basin affected by a simplified glaciation scenario consisting of a single cycle of ice sheet advance and retreat. The simulations are used to provide an illustrative assessment of the hydrogeological and geochemical stability of this sedimentary basin over a time period of 32,500 years. The results suggest a high degree of geochemical stability. (author)

  11. Timing and extent of early marine oxygen isotope stage 2 alpine glaciation in Skagit Valley, Washington (United States)

    Riedel, Jon L.; Clague, John J.; Ward, Brent C.


    Twenty-two new radiocarbon ages from Skagit valley provide a detailed chronology of alpine glaciation during the Evans Creek stade of the Fraser Glaciation (early marine oxygen isotope stage (MIS) 2) in the Cascade Range, Washington State. Sediments at sites near Concrete, Washington, record two advances of the Baker valley glacier between ca. 30.3 and 19.5 cal ka BP, with an intervening period of glacier recession about 24.9 cal ka BP. The Baker valley glacier dammed lower Skagit valley, creating glacial Lake Concrete, which discharged around the ice dam along Finney Creek, or south into the Sauk valley. Sediments along the shores of Ross Lake in upper Skagit valley accumulated in glacial Lake Skymo after ca. 28.7 cal ka BP behind a glacier flowing out of Big Beaver valley. Horizontally laminated silt and bedded sand and gravel up to 20 m thick record as much as 8000 yr of deposition in these glacially dammed lakes. The data indicate that alpine glaciers in Skagit valley were far less extensive than previously thought. Alpine glaciers remained in advanced positions for much of the Evans Creek stade, which may have ended as early as 20.8 cal ka BP.

  12. Simulation of The Weichselian Glaciation In Fennoscandia With The Ice-sheet Model Sicopolis (United States)

    Forsström, P.-L.; Sallasmaa, O.; Greve, R.; Zwinger, T.

    In order to reconstruct the palaeo-glaciation in Fennoscandia during the last (Weich- selian) ice age, simulations with the dynamic/thermodynamic ice-sheet model SICOPOLIS are carried out. Model time is from 250 kyr BP until the present. Cli- matic forcing is based on present distributions of mean annual surface temperature and precipitation over the region, which are derived from the NCEP/NCAR Reanal- ysis Project and University of Delaware (GHCN and Legates &Wilmott, 1990) data sets. For the past, these distributions are modified due to climatic changes as reflected by the GRIP 18O record and changes in surface elevation. Emphasis is put on the Last Glacial Maximum (LGM) ca. 20 kyr BP. It turns out that the glaciation patterns vary to some extent for the two different data sets and depend strongly on the param- eters which determine the past variations of surface temperature and precipitation. By comparing the results with geological reconstructions of maximum ice extent, reason- able values for these parameters can be estimated. We discuss the simulated dynamic and thermodynamic state of the Scandinavian ice sheet at the LGM and the timing and pattern of deglaciation during the transition to the Holocene.

  13. Exploring the MIS M2 glaciation occurring during a warm and high atmospheric CO2 Pliocene background climate (United States)

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


    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.

  14. Postglacial adjustment of steep, low-order drainage basins, Canadian Rocky Mountains (United States)

    Hoffmann, T.; Müller, T.; Johnson, E. A.; Martin, Y. E.


    is generally argued that Pleistocene glaciation results in increased sediment flux in mountain systems. An important, but not well constrained, aspect of Pleistocene glacial erosion is the geomorphic decoupling of cirque basins from main river systems. This study provides a quantitative link between glacier-induced basin morphology, postglacial erosion, and sediment delivery for mountain headwaters (with basin area cirque glaciers, which we classify into headwater basins with either cirque or noncirque morphology. Despite steeper slope gradients in cirque basins, higher-mean postglacial erosion rates in basins with noncirque morphology (0.43-0.6 mm a-1) compared to those in cirques (0.19-0.39 mm a-1) suggest a more complex relationship between hillslope erosion and slope gradient in calcareous mountain environments than implied by the threshold hillslope concept. Higher values of channel profile concavity and lower channel gradients in cirques imply lower transport capacities and, thus, lower sediment delivery ratios (SDR). These results are supported by (i) postglacial SDR values for cirques and noncirque basins of 28%, respectively, and (ii) larger fan sizes at outlets of noncirque basins compared to cirques. Although small headwater basins represent the steepest part of mountain environments and erode significant postglacial sediment, the majority of sediment remains in storage under interglacial climatic conditions and does not affect large-scale mountain river systems.

  15. Geomorphologic evolution and environmental changes in the Shaluli Mountain region during the Quaternary

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shangzhe; XU Liubing; CUI Jianxin; ZHANG Xiaowei; ZHAO Jingdong


    Geologic and geomorphologic evidence from the Shaluli Mountain indicates that the planation surface that formed in the Late Tertiary disintegrated during the Late Pliocene-Early Quaternary. At the same time, rift basins appeared on some parts of the planation surface, and began to accumulate fluvial-lacustrine sediment. These are interpreted as being the response of this region to Phase-A of the Qingzang Tectonic Movement. After this, the Shaluli Mountain continued to rise in several pulses. Faulting and incision by some large tributaries of the Jinsha and Yalong Rivers resulted in several rift river valleys and the earliest terraces. Generally, the planation surface in this region had been uplifted to about 3500-3700 m a.s.l. no later than 550-600 ka BP, after the Kunlun-Huanghe Tectonic Movement, and coupled with global glacial climate, and resulted in the earliest glaciation recognized so far in the Hengduan Mountains. At the same time, loess was deposited in the Ganzi area of the northern Shaluli Mountain. During the last glacial period, the Shaluli Mountain approached its present altitude and developed several large ice caps, such as the Daocheng Ice Cap and Xinlong Ice Cap, as well as several huge valley glaciers. These paleoglaciers produced some of the most spectacular glacial topography on the Tibetan Plateau.

  16. Present-day glaciation of Western Asia (on the Turkey territory

    Directory of Open Access Journals (Sweden)

    A. V. Zimnitskiy


    Full Text Available Mean annual air temperatures, total amount of precipitation, current state of glaciers and changes of their areas on some mountains of the Turkish territory are analyzed. The following regions are considered: East-Pontus Mountains, south-eastern part of the Taurus Mountains, volcanic regions Tendurek, Erciyes, and volcanic zone around the Wang Lake. There are seventy glaciers in these regions with their total area of 16.5 km2. It is shown that mostly the present-day glaciers are in state of degradation, and the rock glaciers are typical among them.

  17. Glacier melt buffering sustains river flow in the Pamir Mountains (United States)

    Pohl, Eric; Andermann, Christoff; Gloaguen, Richard


    Central Asia's water resources and agricultural practices depend on snow and glacier melts in the high mountains. The Amu Darya, the main river draining the Pamir Mountains, exemplifies the resulting seasonality in stream flow. In winter, comparably low amounts of groundwater discharge feed the streams, while the bulk of precipitation is provided and stored as snow. Successive melting of snow cover and glaciers during summer releases these stored waters to the swelling rivers. Despite a strong variability in precipitation and temperatures over the entire Pamir Mountain region, river flow shows severely less variability. We investigate what processes lead to this apparent discrepancy by using a simple but robust hydrological model that we thoroughly validate with remote sensing snow cover observations, Gravity Recovery and Climate Experiment (GRACE) data, highlighting changes in total water storage, and hydrograph comparison. We find that glaciers play a paramount role by buffering extreme meteorological conditions to sustain stream flow. In a simplified scheme, low precipitation amounts in winter result in small snow stocks, compensated for by more intensive glacier melt, and vice versa. By carrying out analyses over the extensive catchment area of the Amu Darya in the high mountain domain, we highlight regional differences in the effectiveness of this mechanism. Regional influences of wind systems and associated moisture transport as well as glaciated area emerge as main factors. Modeled negative glacier mass balances between -0.38 and -0.93 m/year agree with other studies based on geodetic methods and indicate a future reduction in stream flow sustainability. This not only exacerbates the conflict potential between riparian countries downstream, but also means that extreme weather events are more likely to cause floods and droughts.

  18. Comment on "Quaternary glaciations: from observations to theories" by D. Paillard [Quat. Sci. Rev. 107 (2015), 11-24 (United States)

    Bol'shakov, Vyacheslav A.; Kuzmin, Yaroslav V.


    In the invited review by Paillard (2015), comprehensive information about both theoretical and empirical studies of Pleistocene glaciations and their causes are presented. D. Paillard's review concludes that Milankovitch's (1930, 1941) theory cannot explain the 100,000 yr periodicity of glaciations within the last one million years, and that an additional factor must be responsible for global climate fluctuations. According to Paillard (2015), changes in the carbon dioxide (CO2) content of the atmosphere are responsible. This statement radically alters the conventional viewpoint about the leading role of orbital variations on global Pleistocene climate (e.g., Hays et al., 1976).

  19. Trace metal records of regional paleoenvironmental variability in Pennsylvanian (Upper Carboniferous) black shales (United States)

    Cruse, A.M.; Lyons, T.W.


    Regional geochemical differences within a laterally continuous, cyclic Pennsylvanian (Upper Carboniferous) shale in midcontinent North America are interpreted in light of models of glacioeustatic forcing and new views on water-column paleoredox stability and trace-metal behavior in black shale environments. Specifically, we characterize differences in transition metal (Fe, Mn, Mo, V, Ni, Zn, Pb and U) concentrations in black shales of the Hushpuckney Shale Member of the Swope Limestone in Iowa and equivalent black shale beds of the Coffeyville Formation in Oklahoma. Although C-S-Fe systematics and uniform 34S-depleted isotope ratios of pyrite indicate pervasive euxinic deposition (anoxic and sulfidic bottom waters) for these shales, regional variations can be inferred for the efficiency of Mo scavenging and for the rates of siliciclastic sedimentation as expressed in spatially varying Fe/Al ratios. Black shales in Iowa show Mo enrichment roughly five times greater than that observed in coeval euxinic shales in Oklahoma. By contrast, Fe/Al ratios in Oklahoma shales are as much as five times greater than the continental ratio of 0.5 observed in the over- and underlying oxic facies and in the coeval black shales in Iowa. Recent work in modern marine settings has shown that enrichments in Fe commonly result from scavenging in a euxinic water column during syngenetic pyrite formation. In contrast to Fe, the concentrations of other transition metals (Mo, V, Ni, Pb, Zn, U) are typically more enriched in the black shales in Iowa relative to Oklahoma. The transition metal trends in these Paleozoic shales are reasonably interpreted in terms of early fixation in organic-rich sediments due to euxinic water-column conditions. However, regional variations in (1) rates of siliciclastic input, (2) organic reservoirs, including relative inputs of terrestrial versus marine organic matter, and (3) additional inputs of metals to bottom waters from contemporaneous hydrothermal vents

  20. Diagenesis and porosity evolution of tight sand reservoirs in Carboniferous Benxi Formation, Southeast Ordos Basin (United States)

    Hu, Peng; Yu, Xinghe; Shan, Xin; Su, Dongxu; Wang, Jiao; Li, Yalong; Shi, Xin; Xu, Liqiang


    The Ordos Basin, situated in west-central China, is one of the oldest and most important fossil-fuel energy base, which contains large reserves of coal, oil and natural gas. The Upper Palaeozoic strata are widely distributed with rich gas-bearing and large natural gas resources, whose potential is tremendous. Recent years have witnessed a great tight gas exploration improvement of the Upper Paleozoic in Southeastern Ordos basin. The Carboniferous Benxi Formation, mainly buried more than 2,500m, is the key target strata for hydrocarbon exploration, which was deposited in a barrier island and tidal flat environment. The sandy bars and flats are the favorable sedimentary microfacies. With an integrated approach of thin-section petrophysics, constant velocity mercury injection test, scanning electron microscopy and X-ray diffractometry, diagenesis and porosity evolution of tight sand reservoirs of Benxi Formation were analyzed in detail. The result shows that the main lithology of sandstone in this area is dominated by moderately to well sorted quartz sandstone. The average porosity and permeability is 4.72% and 1.22mD. The reservoirs of Benxi Formation holds a variety of pore types and the pore throats, with obvious heterogeneity and poor connection. Based on the capillary pressure curve morphological characteristics and parameters, combined with thin section and phycical property data, the reservoir pore structure of Benxi Formation can be divided into 4 types, including mid pore mid throat type(I), mid pore fine throat type(II), small pore fine throat type(III) and micro pro micro throat type(Ⅳ). The reservoirs primarily fall in B-subsate of middle diagenesis and late diagenesis, which mainly undergo compaction, cmentation, dissolution and fracturing process. Employing the empirical formula of different sorting for unconsolideated sandstone porosity, the initial sandstone porosity is 38.32% on average. Quantitative evaluation of the increase and decrease of

  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)


    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. Organic geochemistry of Upper Carboniferous bituminous coals and clastic sediments from the Lublin Coal Basin (United States)

    Gola, Marek R.; Karger, Michał; Gazda, Lucjan; Grafka, Oliwia


    Bituminous coals and clastic rocks from the Lublin Formation (Pennsylvanian, Westphalian B) were subjected to detailed biomarker and Rock-Eval analyses. The investigation of aliphatic and aromatic fractions and Rock-Eval Tmax suggests that the Carboniferous deposits attained relatively low levels of thermal maturity, at the end of the microbial processes/initial phase of the oil window. Somewhat higher values of maturity in the clastic sediments were caused by postdiagenetic biodegradation of organic matter. The dominance of the odd carbon-numbered n-alkanes in the range n-C25 to n-C31 , high concentrations of moretanes and a predominance of C 28 and C29 steranes are indicative of a terrigenous origin of the organic matter in the study material. This is supported by the presence of eudesmane, bisabolane, dihydro-ar-curcumene and cadalene, found mainly in the coal samples. In addition, tri- and tetracyclic diterpanes, e. g. 16β(H)-kaurane, 16β(H)-phyllocladane, 16α(H)-kaurane and norisopimarane, were identified, suggesting an admixture of conifer ancestors among the deposited higher plants. Parameters Pr/n-C17 and Rdit in the coal samples show deposition of organic matter from peat swamp environments, with the water levels varying from high (water-logged swamp) to very low (ephemeral swamp). Clastic deposits were accumulated in a flood plain environment with local small ponds/lakes. In pond/lake sediments, apart from the dominant terrigenous organic matter, research also revealed a certain quantity of algal matter, indicated, i.a., by the presence of tricyclic triterpanes C28 and C29 and elevated concentrations of steranes. The Paq parameter can prove to be a useful tool in the identification of organic matter, but the processes of organic matter biodegradation observed in clastic rocks most likely influence the value of the parameter, at the same time lowering the interpretation potential of these compounds. The value of Pr/Ph varies from 0.93 to 5.24 and from 3

  3. 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)


    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.

  4. Deglacial history of the Pensacola Mountains, Antarctica from glacial geomorphology and cosmogenic nuclide surface exposure dating (United States)

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


    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.

  5. Rocky Mountain Arsenal Timeline (United States)

    US Fish and Wildlife Service, Department of the Interior — This document details all of the major events having occurred at the Rocky Mountain Arsenal from it's establishment on May 2, 1942 up through the document's release...

  6. Landforms of High Mountains

    Directory of Open Access Journals (Sweden)

    Derek A. McDougall


    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.

  7. Rocky Mountain spotted fever (United States)

    ... Mountain spotted fever is caused by the bacteria Rickettsia rickettsii (R. Rickettsii) , which is carried by ticks. ... Saunders; 2014:chap 212. Walker DH, Blaton LS. Rickettsia rickettsii and other spotted fever group rickettsiae (Rocky ...

  8. Diurnal variation of mountain waves

    Directory of Open Access Journals (Sweden)

    R. M. Worthington


    Full Text Available Mountain waves could be modified as the boundary layer varies between stable and convective. However case studies show mountain waves day and night, and above e.g. convective rolls with precipitation lines over mountains. VHF radar measurements of vertical wind (1990–2006 confirm a seasonal variation of mountain-wave amplitude, yet there is little diurnal variation of amplitude. Mountain-wave azimuth shows possible diurnal variation compared to wind rotation across the boundary layer.

  9. Late Carboniferous tectonic subsidence in South Wales: implications for Variscan basin evolution and tectonic history in SW Britain

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, P.M.; Gayer, R.A. [University of Cardiff, Cardiff (United Kingdom). Dept. of Earth Sciences


    Detailed stratigraphic data were used to backstrip seven sections from the Carboniferous South Wales coal basin. Resulting tectonic subsidence curves for the interval 319-305 Ma (Namurian-Westphalian D) are convex-up, indicating increasing subsidence rate with time, with rates between 130 and 250 m Ma{sup -1} suggesting a foreland basin setting. Forward modelling of subsidence due to flexural loading in front of a propagating orogenic wedge shows that an orogenic load migrating in a north-northeasterly direction across SW England between 319 and 305 Ma could have generated the backstripped subsidence patterns. Sensitivity tests show that while many of the forward model parameters are poorly constrained, and the model results non-unique, backstripped subsidence patterns allow reasonable constraint on the different model cases, so that model predictions can be treated as one possibility in a limited range. The predicted load evolution is consistent with current knowledge of tectonic and stratigraphic features of SW England. These results suggest that subsidence in other Late Carboniferous UK basins may also have been influenced by flexure due to a propagating orogenic load.


    Energy Technology Data Exchange (ETDEWEB)

    A.M. Simmons


    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.

  11. Depositional setting and geochemistry of phosphorites and metalliferous black shales in the Carboniferous-Permian Lisburne Group, Northern Alaska (United States)

    Dumoulin, Julie A.; Slack, John F.; Whalen, Michael T.; Harris, Anita G.


    Phosphatic rocks are distributed widely in the Lisburne Group, a mainly Carboniferous carbonate succession that occurs throughout northern Alaska. New sedimentologic, paleontologic, and geochemical data presented here constrain the geographic and stratigraphic extent of these strata and their depositional and paleogeographic settings. Our findings support models that propose very high oxygen contents of the Permo-Carboniferous atmosphere and oceans, and those that suggest enhanced phosphogenesis in iron-limited sediments; our data also have implications for Carboniferous paleogeography of the Arctic. Lisburne Group phosphorites range from granular to nodular, are interbedded with black shale and lime mudstone rich in radiolarians and sponge spicules, and accumulated primarily in suboxic outer- to middle-ramp environments. Age constraints from conodonts, foraminifers, and goniatite cephalopods indicate that most are middle Late Mississippian (early Chesterian; early late Visean). Phosphorites form 2- to 40-cm-thick beds of sand- to pebble-sized phosphatic peloids, coated grains, and (or) bioclasts cemented by carbonate, silica, or phosphate that occur through an interval =12 m thick. High gamma-ray response through this interval suggests strongly condensed facies related to sediment starvation and development of phosphatic hardgrounds. Phosphorite textures, such as unconformity-bounded coated grains, record multiple episodes of phosphogenesis and sedimentary reworking. Sharp bed bases and local grading indicate considerable redeposition of phosphatic material into deeper water by storms and (or) gravity flows. Lisburne Group phosphorites contain up to 37 weight percent P2O5, 7.6 weight percent F, 1,030 ppm Y, 517 ppm La, and 166 ppm U. Shale-normalized rare earth element (REE) plots show uniformly large negative Ce anomalies Ce/Ce*=0.11 + or - 0.03) that are interpreted to reflect phosphate deposition in seawater that was greatly depleted in Ce due to increased

  12. Reconstructing the groundwater flow in the Baltic Basin during the Last glaciation (United States)

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


    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

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


    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 Gondwana

  14. An example of polygenetic geomorphologic development (Karst-Glacial-Tectonics on Munzur Mountains: Kepir Cave-Elbaba spring karstic system

    Directory of Open Access Journals (Sweden)

    Zeynel Çılğın


    Full Text Available The study area is located at the intersection of a karstic plateau basin in the Munzur Mountain range and a low-lying karstic discharge area in the Ovacık Plain. The mountain range extends east to west and the glacial plain runs parallel in similar direction. The research area is an excellent microcosm of a polygenic morphological karst system. The mountain terrain visible today is dramatic barren landscape and the by-product of multiple, interrelated processes, such as glaciations, karstification and tectonics. The insurgence waters cut into the sediment, gain velocity, and then disappear into a seven meter high by seven meter wide swallow hole cave entrance at 2600m. In the past, pre-Pleistocene dolines had helped transform this area into an icefield landscape. When glaciation period ended, karstic process revived again during Holocene and Kepir Cave has operated as a swallow hole again. The main factors of change can be attributed to glaciations in Pleistocene and intensified karstification during the Holocene. The thick stacking limestone or massif provides the geologic structure for underground drainage and the formation of what may be a significant and deep cave system. The cave system appears to be developing vertically along a prominent fault that is visible just inside the swallow hole entrance. The resurgence, Elbaba, must be related to the Ovacık Fault extending at the northern edge of Ovacık Plain. This karstic system continues to develop as an active system fed by significant snow and rain waters.

  15. Glaciation of northern slopes of Turkestan and Alai Ranges and its present-day dynamics

    Directory of Open Access Journals (Sweden)

    R. A. Usubaliev


    Full Text Available Special features of development and existence of present-day glaciation of the Turkistan and Alay ridges are being examined in current climate change. It is found that the main climate elements – air temperature and atmospheric precipitations tend to rise in the highland zones of these ridges. Though, an air temperature rose more intensively than in Inner Tien-Shan, and glacier degradation rates are more intensive here. For 33–43 years, the glaciers of five river basins reduced in its area extent for more than 20%. An increase of a number of glaciers is characteristically under classification of more large ones. Small glaciers sited rather in low hypsometrical levels, are quite disappeared

  16. The role of sub-milankovitch climatic forcing in the initiation of the northern hemisphere glaciation (United States)

    Willis; Kleczkowski; Briggs; Gilligan


    Mechanisms responsible for the initiation of major glaciation in the Northern Hemisphere at about 2.75 million years ago are poorly understood. A laminated terrestrial sequence from Pula maar, Hungary, containing about 320,000 years in annual layers between 3.05 and 2. 60 million years ago, provides a detailed record of rates of climatic change across this dramatic transition. An analysis of the record implies that climatic variations at sub-Milankovitch frequencies (less than or equal to 15,000 years) were an important driving force during this transitional interval and that, as the threshold was approached, these increased in frequency and amplitude, possibly providing the final trigger for the amplification of Northern Hemisphere ice sheets.

  17. 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)


    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)

  18. Meltwater channel scars and the extent of Mid-Pleistocene glaciation in central Pennsylvania (United States)

    Marsh, Ben


    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.

  19. Aquatic insect assemblages associated with subalpine stream segment types in relict glaciated headwaters (United States)

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


    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.

  20. Latest Pleistocene and Holocene glaciation of Baffin Island, Arctic Canada: key patterns and chronologies (United States)

    Briner, Jason P.; Davis, P. Thompson; Miller, Gifford H.


    Melting glaciers and ice caps on Baffin Island contribute roughly half of the sea-level rise from all ice in Arctic Canada, although they comprise only one-fourth of the total ice in the region. The uncertain future response of arctic glaciers and ice caps to climate change motivates the use of paleodata to evaluate the sensitivity of glaciers to past warm intervals and to constrain mechanisms that drive glacier change. We review the key patterns and chronologies of latest Pleistocene and Holocene glaciation on Baffin Island. The deglaciation by the Laurentide Ice Sheet occurred generally slowly and steadily throughout the Holocene to its present margin (Barnes Ice Cap) except for two periods of rapid retreat: An early interval ˜12 to 10 ka when outlet glaciers retreated rapidly through deep fiords and sounds, and a later interval ˜7 ka when ice over Foxe Basin collapsed. In coastal settings, alpine glaciers were smaller during the Younger Dryas period than during the Little Ice Age. At least some alpine glaciers apparently survived the early Holocene thermal maximum, which was several degrees warmer than today, although data on glacier extent during the early Holocene is extremely sparse. Following the early Holocene thermal maximum, glaciers advanced during Neoglaciation, beginning in some places as early as ˜6 ka, although most sites do not record near-Little Ice Age positions until ˜3.5 to 2.5 ka. Alpine glaciers reached their largest Holocene extents during the Little Ice Age, when temperatures were ˜1-1.5 °C cooler than during the late 20th century. Synchronous advances across Baffin Island throughout Neoglaciation indicate sub-Milankovitch controls on glaciation that could involve major volcanic eruptions and solar variability. Future work should further elucidate the state of glaciers and ice caps during the early Holocene thermal maximum and glacier response to climate forcing mechanisms.

  1. Triple oxygen isotope evidence for elevated CO2 levels after a Neoproterozoic glaciation. (United States)

    Bao, Huiming; Lyons, J R; Zhou, Chuanming


    Understanding the composition of the atmosphere over geological time is critical to understanding the history of the Earth system, as the atmosphere is closely linked to the lithosphere, hydrosphere and biosphere. Although much of the history of the lithosphere and hydrosphere is contained in rock and mineral records, corresponding information about the atmosphere is scarce and elusive owing to the lack of direct records. Geologists have used sedimentary minerals, fossils and geochemical models to place constraints on the concentrations of carbon dioxide, oxygen or methane in the past. Here we show that the triple oxygen isotope composition of sulphate from ancient evaporites and barites shows variable negative oxygen-17 isotope anomalies over the past 750 million years. We propose that these anomalies track those of atmospheric oxygen and in turn reflect the partial pressure of carbon dioxide (P(CO2)) in the past through a photochemical reaction network linking stratospheric ozone to carbon dioxide and to oxygen. Our results suggest that P(CO2) was much higher in the early Cambrian than in younger eras, agreeing with previous modelling results. We also find that the (17)O isotope anomalies of barites from Marinoan (approximately 635 million years ago) cap carbonates display a distinct negative spike (around -0.70 per thousand), suggesting that by the time barite was precipitating in the immediate aftermath of a Neoproterozoic global glaciation, the P(CO2) was at its highest level in the past 750 million years. Our finding is consistent with the 'snowball Earth' hypothesis and/or a massive methane release after the Marinoan glaciation.

  2. 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.


    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

  3. Seismic interpretation of dinantian carbonate platforms in the Netherlands; implications for the palaeogeographical and structural development of the Northwest European Carboniferous Basin

    NARCIS (Netherlands)

    Kombrink, H.; Lochem, H. van; Zwan, K.J. van der


    The Northwest European Carboniferous Basin is characterized by a series of carbonate platforms and intervening shale-dominated troughs during the Dinantian Sub-period. These structures have been mainly found along the margins of the basin. Here we present the results of an investigation of high-qual

  4. Seismic interpretation of dinantian carbonate platforms in the Netherlands; implications for the palaeogeographical and structural development of the Northwest European Carboniferous Basin

    NARCIS (Netherlands)

    Kombrink, H.; Lochem, H. van; Zwan, K.J. van der


    The Northwest European Carboniferous Basin is characterized by a series of carbonate platforms and intervening shale-dominated troughs during the Dinantian Sub-period. These structures have been mainly found along the margins of the basin. Here we present the results of an investigation of high-qual

  5. 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)


    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

  6. 塔里木盆地北缘上石炭统砂岩碎屑组分及其对物源类型和构造属性的指示%Detrital composition of Upper Carboniferous sandstone in northern Tarim basin and its implications for provenance and tectonic attributes

    Institute of Scientific and Technical Information of China (English)

    杨栋栋; 李双应; 王松; 万秋; 赵大千; 徐锦龙


    Since the late Paleozoic, the south Tianshan Mountain has gone through a series of collision and micro-plate collage events, which have had obvious reflection in the sedimentation and tectonic evolution of northern Tarim basin. The analysis of depositional provenance is an important method for understanding basin evolution and interpreting tectonic background, and is also the first prerequisite for confirming the evolution of the basin. The variation in the composition of depositional provenances reflects the relationship between the uplift of basin margin orogen and the basin subsidence. With the improvement of modem analytical techniques, the provenance analytical methods have increased in number, become gradually perfected in quality and complemented each other. Based on Dickinson's provenance analytical method, the authors studied and analyzed sandstone detrital composition and source rocks of Upper Carboniferous sandstone along different geological sections in northern Tarim basin. The results show that the major types of the Upper Carboniferous sandstone are quartz sandstone and lithic quartz sandstone, with low compositional maturity, and the average Q/(F+ L) in Cedaya, Dashankou hydropower station and Bayinbuluke geological section are respectively 1.80, 3.11, 3.32. The detrital composition is mainly quartz and subordinately feldspar and some rock debris, with minor organic matrix or biotite. According to the study of sandstone detrital compositions, sandstone of Upper Carboniferous Ayilihe Formation in northern Tarim basin is composed averagely of 70.7% quartz (53%~86%), 7.1% feldspar (5%~17%), and22.5 % rock debris (20%~30%). Metamorphic debris and sedimentary debris are mainly existent in this area, while in Cedaya, volcanic debris possesses 42%. On the basis of Dickinson's triangular plot and the characteristics of rock debris, the Upper Carboniferous provenance in northern Tarim basin is characterized by the recycled orogen type, and the primary

  7. Depositional settings, correlation, and age carboniferous rocks in the western Brooks Range, Alaska (United States)

    Dumoulin, J.A.; Harris, A.G.; Blome, C.D.; Young, L.E.


    The Kuna Formation (Lisburne Group) in northwest Alaska hosts the Red Dog and other Zn-Pb-Ag massive sulfide deposits in the Red Dog district. New studies of the sedimentology and paleontology of the Lisburne Group constrain the setting, age, and thermal history of these deposits. In the western and west-central Brooks Range, the Lisburne Group includes both deep- and shallow-water sedimentary facies and local volcanic rocks that are exposed in a series of thrust sheets or allochthons. Deep-water facies in the Red Dog area (i.e., the Kuna Formation and related rocks) are found chiefly in the Endicott Mountains and structurally higher Picnic Creek allochthons. In the Red Dog plate of the Endicott Mountains allochthon, the Kuna consists of at least 122 m of thinly interbedded calcareous shale, calcareous spiculite, and bioclastic supportstone (Kivalina unit) overlain by 30 to 240 m of siliceous shale, mudstone, calcareous radiolarite, and calcareous lithic turbidite (Ikalukrok unit). The Ikalukrok unit in the Red Dog plate hosts all massive sulfide deposits in the area. It is notably carbonaceous, is generally finely laminated, and contains siliceous sponge spicules and radiolarians. The Kuna Formation in the Key Creek plate of the Endicott Mountains allochthon (60-110 m) resembles the Ikalukrok unit but is unmineralized and has thinner carbonate layers that are mainly organic-rich dolostone. Correlative strata in the Picnic Creek allochthon include less shale and mudstone and more carbonate (mostly calcareous spiculite). Conodonts and radiolarians indicate an age range of Osagean to early Chesterian (late Early to Late Mississippian) for the Kuna in the Red Dog area. Sedimentologic, faunal, and geochemical data imply that most of the Kuna formed in slope and basin settings characterized by anoxic or dysoxic bottom water and by local high productivity. Shallow-water facies of th e Lisburne Group in the Red Dog area are present locally in the Endicott Mountains

  8. ICESat laser altimetry over small mountain glaciers (United States)

    Treichler, Désirée; Kääb, Andreas


    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 m ice per year. This regional

  9. Mountain saved. is a mountain earned

    Energy Technology Data Exchange (ETDEWEB)

    Margolis, K.

    The Anaconda Copper Company boasted that the smokestack on its Washee smelter mill was the world's tallest. It also was probably the world's deadliest. Mysterious livestock deaths began occurring in 1906. They seemed to concentrate in the path of the prevailing westerly winds, carrying the Washee's smelter smoke plume toward Mt. Haggin. As evidence mounted that the deaths were connected to particulate fallout from the smelter (largely oxides of zinc, arsenic, lead, and copper), there were rumblings of lawsuits against Anaconda. The company felt threatened, but did not possess the technology to cure the situation. To protect itself, Anaconda purchased all the lands that were affected by fallout from the smelter smokestack. The result was the formation of the 154,000-acre Mt. Haggin Ranch. Today, the Anaconda Copper Company uses sophisticated pollution abatement equipment, and it is possible to see the healing that has taken place in recent years. The ranch includes rugged mountain peaks and ridges, high mountain valleys, and rolling foothills. A fisherman's paradise, the area also contains 20 mountain lakes, numerous ponds, and over 60 miles of trout streams. The Conservancy has been working to save Mt. Haggin since 1969. Negotiations have involved not only the fee owner--Mt. Haggin Livestock, Inc.--but also parties holding grazing and timber contracts, a variety of public agencies, and the Anaconda Company, which still holds some rights over the portion of the property not yet purchased by the Conservancy. The Conservancy assists in preserving lands like Mt. Haggin by handling the financial and legal aspects of land purchases. The Conservancy is allocating property to two ultimate recipients: the U.S. Forest Service and the montana Department of Fish and Game.

  10. 中国第四纪冰川作用与深海氧同位素阶段的对比和厘定%Division of glaciation and correlation between the Quaternary glaciation in China and the marine isotope stage

    Institute of Scientific and Technical Information of China (English)

    张威; 刘蓓蓓; 崔之久; 李永化; 董应巍; 于治龙; 李洋洋


    With the development of Quaternary glacier research and the increase of the absolute ages, comparison of glacial sequence and marine isotope stage (MIS) is better than before. The further division of glaciation (glacial stage) and interglacial (interglacial stage) lead to the emergence of some problems reflected by the influence of the procedures of traditional glaciation on the comparison between Quaternary glaciation in China and MIS. The main problems are as follows: the glacial sequence with absolute ages corrected the previous glaciation division according to the relative geomorphology, however, the modified results have not propagated as soon as possible. The correlation between glaciation and the even stage of MIS is not reasonable. Logical contradiction exists in the comparison between the glaciation, interglacial and MIS. An abuse of double name with time and location of the glacial sequence exist in the division of Quaternary glaciation in China at present. According to the comparison between Quaternary glaciation in China and MIS, together with the research of control of climate change and tectonic movement on the evolution of the geomorphology, main conclusions can be drawn as follows. (1) It is useful to find one or more new events of Quaternary glacial advance when correlating the glaciation (glacial stage) or inter-glacial (stage) to the even stage of the MIS in the future. (2) As the influence of 100 ka ratio of the earth orbit, the glacial development in China has been greatly influenced by the major climate change since the middle Pleistocene. The glacial extents are accordant with the global ice volume from the Kunlun glaciation to Zhonglianggan glaciation. However, the glacial extents of the early and/or middle stages were not consistent with the global ice volume during the last glacial cycle. It is intensively indicated that the glacial occurrence might depend on the coupling control of the regional climate and the tectonic uplift. The name of

  11. Late Carboniferous N-MORB-type basalts in central Inner Mongolia, China: Products of hydrous melting in an intraplate setting? (United States)

    Pang, Chong-Jin; Wang, Xuan-Ce; Xu, Bei; Zhao, Jian-Xin; Feng, Yue-Xing; Wang, Yan-Yang; Luo, Zhi-Wen; Liao, Wen


    Petrogenesis of the ca. 310 Ma Benbatu basalts in central Inner Mongolia is crucial for constraining the evolution of the Xing'an Mongolia Orogenic Belt (XMOB), eastern segment of the Central Asian Orogenic Belt. The Benbatu basalts have low initial 87Sr/86Sr ratios (0.7042-0.7048), positive εNd(t) (+ 8.99 to + 9.24) and εHf(t) values (+ 15.38 to + 15.65), and are characterized by relatively flat rare earth element patterns and enrichment of Rb, U, Pb, Zr and Hf, but depletion of Nb, Ta, Sr and Ti, resembling those of the normal Mid-Ocean-Ridge Basalt (N-MORB). Variations of trace element ratios (e.g., Sm/Yb and La/Sm) suggest that the basalts were derived from spinel peridotites, with a melting depth of recycling water in the generation of the Late Carboniferous magmatism in this region.

  12. Early post-metamorphic, Carboniferous blastoid reveals the evolution and development of the digestive system in echinoderms. (United States)

    Rahman, Imran A; Waters, Johnny A; Sumrall, Colin D; Astolfo, Alberto


    Inferring the development of the earliest echinoderms is critical to uncovering the evolutionary assembly of the phylum-level body plan but has long proven problematic because early ontogenetic stages are rarely preserved as fossils. Here, we use synchrotron tomography to describe a new early post-metamorphic blastoid echinoderm from the Carboniferous (approx. 323 Ma) of China. The resulting three-dimensional reconstruction reveals a U-shaped tubular structure in the fossil interior, which is interpreted as the digestive tract. Comparisons with the developing gut of modern crinoids demonstrate that crinoids are an imperfect analogue for many extinct groups. Furthermore, consideration of our findings in a phylogenetic context allows us to reconstruct the evolution and development of the digestive system in echinoderms more broadly; there was a transition from a straight to a simple curved gut early in the phylum's evolution, but additional loops and coils of the digestive tract (as seen in crinoids) were not acquired until much later.

  13. Role of N. A. Kudryavtsev in the development of the concept regarding abiogenesis of natural carboniferous substances

    Energy Technology Data Exchange (ETDEWEB)

    Florovskaya, V.N.


    An examination is made of the scientific contribution of N. A. Kudryavtsev to the development of the concept regarding abiogenesis. Some of the results of the studies investigating the evolution of carboniferous substances in the process of endogenous mineral formation are presented. It is indicated that oil and life are products of endogenous transformation of simple carbon compounds in the earth's crust in relation to magma entering it. The conclusion is drawn that the problem of abiogenesis of oil in which genesis of oil is linked by N. A. Kudryavtsev with magma, and the processes of oil formation and ore formation are viewed together is on the agenda of modern geological science.

  14. A Carboniferous Cabinet of Wonders: an example of how the collaboration of art and Earth Sciences can inspire conservation (United States)

    Grey, Melissa; Rogers, Janine


    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

  15. A new brittle star from the early Carboniferous of Poland and its implications on Paleozoic modern-type ophiuroid systematics

    Directory of Open Access Journals (Sweden)

    Ben Thuy


    Full Text Available The fossil record of Paleozoic ophiuroids includes a number of forms which share striking similarities with modern relatives in terms of skeletal morphology. These so called modern-type Paleozoic ophiuroids yield an enormous potential for a better understanding of ophiuroid evolution, yet the scarcity of accurate and sufficiently detailed morphological descriptions available to date precludes any further-reaching assessments. Here, we describe an articulated ophiuroid specimen from the Late Tournaisian (early Carboniferous of Czatkowice quarry, southern Poland, as a new species Aganaster jagiellonicus sp. nov. The good preservation of the specimen allowed for a morphological analysis at a level comparable to recent ophiuroid descriptions. It shows remarkable morphological similarities with extant former ophiolepidids Ophiomusium and Ophiosphalma. The new find thus contributes to a solid basis for future investigations on the position of the modern-type Paleozoic ophiuroid in the phylogeny of the class.

  16. Shenzhousia qilianshanensis gen. et sp. nov. (Protodonata, Meganeuridae), a giant dragonfly from the Upper Carboniferous of China

    Institute of Scientific and Technical Information of China (English)


    A new dragonfly of family Meganeuridae Shenzhousia qilianshanensis gen. et sp. nov., discovered from Ningxia Hui Autonomous Region in North China, is described in the present paper. It has an estimated wingspan of about 450-500 mm and may be the largest fossil insect in Late Carboniferous Namurian Stage discovered by far. The new species is referred to Meganeuridae because of the presence of the characteristic oblique vein between anterior branch of radius (RA) and posterior branch of radius (RP) near the base of RP2. It differs from other genera within the family in the following characteristics: Precostal area short and not extending to the midwing;posterior branch of subcostal vein short, merging into costal vein near the level of originating point of IR2; RP forking earlier than anterior branch of media basally; RP1 + 2 and RP3 + 4 parallel and close to each other for a long distance, and then diverge gradually surpass midwing.


    Thayer, T.P.; Stotelmeyer, Ronald B.


    The Strawberry Mountain Wilderness extends 18 mi along the crest of the Strawberry Range and comprises about 53 sq mi in the Malheur National Forest, Grant County, Oregon. Systematic geologic mapping, geochemical sampling and detailed sampling of prospect workings was done. A demonstrated copper resource in small quartz veins averaging at most 0. 33 percent copper with traces of silver occurs in shear zones in gabbro. Two small areas with substantiated potential for chrome occur near the northern edge of the wilderness. There is little promise for the occurrence of additional mineral or energy resources in the Strawberry Mountain Wilderness.

  18. Himalayan Mountain Range, India (United States)


    Snow is present the year round in most of the high Himalaya Mountain Range (33.0N, 76.5E). In this view taken at the onset of winter, the continuous snow line can be seen for hundreds of miles along the south face of the range in the Indian states of Punjab and Kashmir. The snow line is at about 12,000 ft. altitude but the deep Cenab River gorge is easily delineated as a break along the south edge of the snow covered mountains. '

  19. Glacial Ice Velocity Determination and Correlation from Different Mountain Ranges Using Aster Imagery (United States)

    Pleasants, M.; Haritashya, U. K.


    Mountain glaciers make good indicators of even slight changes in climatic conditions because of their sensitivity to temperature and other environmental changes. Due to the inaccessibility of most mountain glaciers, field based measurements of glacier dynamics, especially ice velocities, has proved to be difficult and unrealistic. Because of this, evaluation of satellite imagery has become useful in the determination of glacial ice velocities and production of ice flow models. The calculation and comparison of ice velocities from three glaciated regions (the Southern Alps of New Zealand, the North-east Nepali Himalaya, and the south-eastern Chugach Mountains of Alaska) is presented here. This study was completed to establish the accuracy and global applicability of the method of precise orthorectification, co-registration, and correlation using the software COSI-Corr and in-house filtering techniques. We chose glaciers from different mountain ranges that present different dynamics to establish a specific ice velocity method. Advanced Spacebourne Thermal Emission and Reflection Radiometer (ASTER) L1A images were chosen as close to annual pairs as possible from the available data at the USGS Global Visualization Viewer (GloVis). This study focuses on the Tasman glacier in New Zealand, the Khumbu glacier in the Himalayas, the previously unstudied Scott glacier in Alaska, and the comparison of these ice velocities to climate data for each region compiled from numerous sources in an attempt to draw conclusions of the behavior of these glaciers in response to current climatic changes.

  20. An Extended Paleozoic Apparent Polar Wander Path for Baltica: new Permo-Carboniferous Paleopoles From the Donbas Region (Ukraine) (United States)

    Hamers, M. F.; Meijers, M. J.; van Hinsbergen, D. J.; van der Meer, D. G.; Langereis, C. G.; Stephenson, R. A.


    An improved Paleozoic apparent polar wander (APW) path for Baltica is presented here on the basis of six new paleopoles that have been determined from samples collected in the Donbas region in the Dniepr-Donets basin in south-eastern Ukraine. Constructing APW paths allows improving paleogeographic reconstructions that reach further back in time than 200 Ma, where the use of oceanic isochrons and hotspot track has limited applicability. The absence of penetrative regional deformation and the subparallel trending bedding attitudes across the basin suggest that our sites did not suffer from local rotations and their results are interpreted as representative for Baltica. The data presented here improve the paleogeographic reconstruction of Baltica within the collage of the supercontinent Pangea. The six new paleopoles cover a time span from earliest Carboniferous (~356 Ma) to early Permian (~295 Ma). In our reconstruction, Baltica was located at a constant latitude of ~5°N during a major part of the Carboniferous, while at ~310 Ma it started to move gradually northward, reaching a paleolatitude of ~13°N at 295 Ma. From ~355 Ma to 295 Ma Baltica experienced a net ~20° clockwise rotation. Our new data differ with the APW path from Torsvik et al. (submitted) in the time span from ~320-300 Ma, wherein they propose a northward movement from more southerly latitudes. From 300 Ma onwards, our path fits the reference path from Torsvik et al. A possible Permian remagnetization of our sites is not likely, considering the rotational differences in the various time spans, and rockmagnetic analyses that have been performed. We also discuss the usage of the TK03 model (Tauxe and Kent (2004), Geoph. Mon. 145, pp 101-116) that allows for the correction of inclination error caused by compaction during burial, which is insignificant for most sites. This suggest that the NRM has been acquired after compaction.

  1. 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


    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

  2. Understand mountain studies from earthquake

    Institute of Scientific and Technical Information of China (English)


    @@ The Sichuan earthquake on 12 May was the most devastating one to hit China over the past 60 years or so. As the affected were mostly mountainous areas, serious damages were caused by various secondary disasters ranging from mountain collapse to the formation of quake lakes. This leaves Prof. DENG Wei, director-general of the Institute of Mountain Hazards and Environment, CAS, much to think about, and he is calling for strengthening studies on mountain science.

  3. 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


    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

  4. Mountain-Plains Curriculum. (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…

  5. Xiuhua Mountain Museum

    Institute of Scientific and Technical Information of China (English)


    XIUHUA Mountain Museum,a building nestled amongthe hills,is the first private museum of the Tujiaethnicity.Its name is an amalgamation of the names ofthe couple who run it,Gong Daoxiu and her husband ChenChuhua.According to Chen,the reason that he put his wife’s

  6. The volcanic response to deglaciation: Evidence from glaciated arcs and a reassessment of global eruption records (United States)

    Watt, Sebastian F. L.; Pyle, David M.; Mather, Tamsin A.

    Several lines of evidence have previously been used to suggest that ice retreat after the last glacial maximum (LGM) resulted in regionally-increased levels of volcanic activity. It has been proposed that this increase in volcanism was globally significant, forming a substantial component of the post-glacial rise in atmospheric CO2, and thereby contributing to climatic warming. However, as yet there has been no detailed investigation of activity in glaciated volcanic arcs following the LGM. Arc volcanism accounts for 90% of present-day subaerial volcanic eruptions. It is therefore important to constrain the impact of deglaciation on arc volcanoes, to understand fully the nature and magnitude of global-scale relationships between volcanism and glaciation. The first part of this paper examines the post-glacial explosive eruption history of the Andean southern volcanic zone (SVZ), a typical arc system, with additional data from the Kamchatka and Cascade arcs. In all cases, eruption rates in the early post-glacial period do not exceed those at later times at a statistically significant level. In part, the recognition and quantification of what may be small (i.e. less than a factor of two) increases in eruption rate is hindered by the size of our datasets. These datasets are limited to eruptions larger than 0.1 km3, because deviations from power-law magnitude-frequency relationships indicate strong relative under-sampling at smaller eruption volumes. In the southern SVZ, where ice unloading was greatest, eruption frequency in the early post-glacial period is approximately twice that of the mid post-glacial period (although frequency increases again in the late post-glacial). A comparable pattern occurs in Kamchatka, but is not observed in the Cascade arc. The early post-glacial period also coincides with a small number of very large explosive eruptions from the most active volcanoes in the southern and central SVZ, consistent with enhanced ponding of magma during

  7. Global snowline and mountain topography: a contrasted view (United States)

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


    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

  8. Subaqueous systems fed by glacially derived hyperpycnal flows: a depositional model for Carboniferous-Permian sandstones of the Itarare Group, Parana Basin; Sistemas subaquosos alimentados por fluxos hiperpicnais glaciogenicos: modelo deposicional para arenitos do Grupo Itarare, Permocarbonifero da Bacia do Parana

    Energy Technology Data Exchange (ETDEWEB)

    Vesely, Fernando Farias [PETROBRAS, Rio de Janeiro, RJ (Brazil). E e P. Gerencia de Estratigrafia]. E-mail:


    The glacial Itarare Group constitutes the lower interval of the Carboniferous-Permian mega sequence in the Parana Basin. Thick glacially related sandstone reservoirs present in this unit contain gas and condensate sourced by Devonian marine shales. Based on outcrop data from the eastern basin margin, the sedimentary facies and stacking patterns were analyzed in order to propose a depositional model for these sandstone successions. It is suggested that the sandstones were deposited subaqueously as pro glacial fans due to melt water-derived highly concentrated hyperpycnal flows. Regional Itarare Group's stratigraphy can be expressed as several unconformity-bounded sequences deposited in a marine glaciated basin during repeated deglaciation episodes. The lower half of each sequence is constituted of thick sand-rich successions typically showing fining-upward and a retrogradational stacking pattern. Eleven facies were recognized, ranging from conglomerates to fine-grained sandstones, massive, graded or stratified. Conglomerates and cross-bedded coarse sandstones represent proximal Subaqueous deposits and were formed as ice-contact out wash fans/aprons due to melt water-derived hyper concentrated and concentrated flows and traction dominated bottom currents. These flows served as feeder systems to stratified, massive or graded turbiditic sandstone lobes deposited more distally. Parallel bedding and climbing ripples present in these beds were formed due to continuous aggradation from waxing and/or waning long-lived turbidity currents. These characteristics typify hyperpycnites and suggest that melt water derived hyperpycnal flows were the main trigger mechanisms to turbidity currents in the Itarare Group. (author)

  9. Digital mountains: toward development and environment protection in mountain regions (United States)

    Jiang, Xiaobo


    Former studies on mountain system are focused on the department or subject characters, i.e. different department and branches of learning carry out researches only for their individual purposes and with individual characters of the subject of interests. As a whole, their investigation is lacking of comprehensive study in combination with global environment. Ecological environment in mountain regions is vulnerable to the disturbance of human activities. Therefore, it is a key issue to coordinate economic development and environment protection in mountain regions. On the other hand, a lot of work is ongoing on mountain sciences, especially depending on the application of RS and GIS. Moreover, the development of the Digital Earth (DE) provides a clue to re-understand mountains. These are the background of the emergence of the Digital Mountains (DM). One of the purposes of the DM is integrating spatial related data and information about mountains. Moreover, the DM is a viewpoint and methodology of understanding and quantifying mountains holistically. The concept of the DM is that, the spatial and temporal data related to mountain regions are stored and managed in computers; moreover, manipulating, analyzing, modeling, simulating and sharing of the mountain information are implemented by utilizing technologies of RS, GIS, GPS, Geo-informatic Tupu, computer, virtual reality (VR), 3D simulation, massive storage, mutual operation and network communication. The DM aims at advancing mountain sciences and sustainable mountain development. The DM is used to providing information and method for coordinating the mountain regions development and environment protection. The fundamental work of the DM is the design of the scientific architecture. Furthermore, construct and develop massive databases of mountains are the important steps these days.

  10. The Effects of Tectonics on Glaciated Landscapes: Evaluating the Glacial Buzzsaw Hypothesis (United States)

    Brocklehurst, S. H.; Whipple, K. X.


    An important aspect of the proposed interactions between plate tectonics processes and climate change is the response of the glacial system to enhanced tectonic uplift rates. Much work has been carried out on the fluvial system and it is well established that rivers must increase their channel gradient to erode at more rapid rates in response to a rise in tectonic uplift rate. Prior studies have revealed a correlation between mean topography and equilibrium line altitude (ELA), regardless of uplift rate, and thus suggested that glaciers are capable of eroding at rates comparable to the fastest tectonic uplift rates. However, it has not been established how this is achieved. Do glaciers have a specific response to increases in uplift rate? We have addressed this question by examining swath and longitudinal profiles, and hypsometry, for a series of glaciated basins in areas of spatially variable tectonic uplift rate (as inferred from fission track ages) in the Southern Alps of New Zealand and around Nanga Parbat in the northwestern Himalaya. We note the following interesting features: (i) Many of the glaciated basins in the most rapidly uplifting areas are associated with tall, steep headwalls. These are seen most dramatically around Nanga Parbat, where headwalls several kilometers high constitute more than 50% of the basin relief, but are also observed in the Southern Alps. (ii) The longitudinal profiles show a steepening associated with increasing uplift rate similar to that observed in river systems. (iii) The hypsometry shows that an increase in uplift rate is associated with an overall steepening of the basin as a whole. This comprises both the hillslope lengthening and the valley steepening described above. (iv) In slowly uplifting areas there tends to be a distinct flattening of the longitudinal profile at the mean Quaternary ELA; in more rapidly uplifting areas this flattening occurs closer to the modern ELA. (v) In New Zealand, mean and maximum elevations do

  11. Uranium Isotope Evidence for Temporary Ocean Oxygenation Following the Sturtian Glaciation (United States)

    Lau, K. V.; Maher, K.; Macdonald, F. A.; Payne, J.


    The link between widespread ocean oxygenation in the Neoproterozoic and the rise of animals has long been debated, largely because the timing and nature of oxygenation of the oceans remain poorly constrained. Strata deposited during the Cryogenian non-glacial interlude (660 to 635 Ma), between the Sturtian and Marinoan Snowball Earth glaciations, contain the earliest fossil evidence of animals. To quantitatively estimate patterns of seafloor oxygenation during this critical interval, we present uranium isotope (δ238U) data from limestone of the Taishir Formation (Fm) in Mongolia in two stratigraphic sections that are separated by ~75 km across the basin. The Taishir Fm hosts two large δ13C excursions that co-vary in total organic and inorganic (carbonate) carbon: a basal carbonate δ13C excursion to -4‰ in the Sturtian cap carbonate, followed by a rise to enriched values of +8‰, a second negative δ13C excursion to -7‰ referred to as the Taishir excursion, followed by a second rise to +10‰. Above the Sturtian glacial deposits, in the stratigraphic interval below the Taishir excursion, δ238U compositions have a mean value that is similar to that of modern seawater. After the Taishir excursion, the δ238U record exhibits a step decrease of ~0.3‰, and δ238U remains approximately constant until the erosional unconformity at the base of the Marinoan glacial deposits. We use a box model to constrain the uranium cycle behavior that best explains our observations. In the model, the best explanation for the less negative post-Sturtian values of δ238U is extensive oxygenation of the seafloor. Moreover, the model demonstrates that the higher δ238U values of the post-Sturtian limestones are inconsistent with an increased flux of uranium to the oceans due to post-Snowball weathering as the primary driver of the excursion. Thus, we favor a scenario in which there was a rise in oxygen levels following the Sturtian glaciation followed by a decrease in seafloor

  12. Timing and climatic drivers for glaciation across semi-arid western Himalayan-Tibetan orogen (United States)

    Dortch, Jason M.; Owen, Lewis A.; Caffee, Marc W.


    Mapping and forty-seven new 10Be ages help define the timing of glaciation in the Ladakh and Pangong Ranges in Northwest India. Five new local glacial stages are defined for the Ladakh Range. From oldest to youngest these include: the Ladakh-4 glacial stage at 81 ± 20 ka; the Ladakh-3 glacial stage (not dated); the Ladakh-2 glacial stage at 22 ± 3 ka; the Ladakh-1 glacial stage (not dated); and the Ladakh Cirque glacial stage at 1.8 ± 0.4 ka. Three local glacial stages are defined for the Pangong Range, which include: the Pangong-2 glacial stage at 85 ± 15 ka; the Pangong-1 glacial stage at 40 ± 3 ka; and the Pangong Cirque glacial stage at 0.4 ± 0.3 ka. The new 10Be ages are combined with 645 recalculated 10Be ages from previous studies to develop the first regional framework of glaciation across the dryland regions of the Greater Himalaya, Transhimalaya, Pamir and Tian Shan at the western end of the Himalayan-Tibetan orogen. Nineteen regional glacial stages are recognized that are termed semi-arid western Himalayan-Tibetan stages (SWHTS). These include: SWHTS 9 at 311 ± 32 ka; SWHTS 7 at 234 ± 44 ka [tentative]; SWHTS 6 at 146 ± 18 ka; SWHTS 5E at 121 ± 11 ka; SWHTS 5A at 80 ± 5 ka; SWHTS 5A- at 72 ± 8 ka; SWHTS 4 at 61 ± 5 ka; SWHTS 3 at 46 ± 4 ka; SWHTS 2F at 30 ± 3 ka; SWHTS 2E at 20 ± 2 ka; SWHTS 2D at 16.9 ± 0.7 ka; SWHTS 2C at 14.9 ± 0.8 ka; SWHTS 2B at 13.9 ± 0.5 ka; SWHTS 2A at 12.2 ± 0.8 ka; SWHTS 1E at 8.8 ± 0.3 ka [tentative]; SWHTS 1D at 6.9 ± 0.2 ka [tentative]; SWHTS 1C at 3.8 ± 0.6 ka; SWHTS 1B at 1.7 ± 0.2 ka; and SWHTS 1A at 0.4 ± 0.1 ka. Regional glacial stages older than 21 ka are broadly correlated with strong monsoons. SWHTS that are 21 ka or younger, have smaller uncertainties and broadly correlate with global ice volume given by marine Oxygen Isotope Stages, and northern hemisphere climatic events (Oldest Dryas, Older Dryas, Younger Dryas, Roman Humid Period, and Little Ice Age).

  13. How Strong is the Case for Proterozoic Low-Latitude Glaciation? (United States)

    Evans, D. A.


    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. Climate instability during the last glaciation recorded in the Yuanbu loess section

    Institute of Scientific and Technical Information of China (English)

    Yimeng Chen


    Abrupt events within the Linxia Yuanbu loess section in the western Loess Plateau in China were investigated.The climatic proxy index of the content of mean grain-size and>4 μm grain-size fraction of the section was used as a climatic indicator,and a moving average method was applied in the statistical analysis to extract the abrupt events recorded in the section.It was found that the loess of the last glaciation recorded not only the abrupt events teleconnected with the high-latitude North Atlantic and Greenland regions but also as many as 15 abrupt events in addition to the Heinrich (H) and Younger Dryas (YD) events.This indicates that abrupt climate changes were typical of the climate changes occurring in the Loess Plateau during the last glaciation.The widely recognized mechanisms of the abrupt climate changes,including the heat transfer theory of the North Atlantic Ocean,the atmospheric circulation theory,and the theory of the interaction between low-latitude ocean and the atmosphere remains to be discussed.Perhaps this problem could be resolved by revealing the relation between the evolution of the features of the East Asian monsoon climate and the climate in the surrounding areas.Through a detailed study of the features of the Heinrich and YD events,criteria on which the abrupt events recorded in the loess could be distinguished were tentatively defined.The events were associated with a large grain size,high carbonate content,high lightness,low susceptibility,low redness and low yellowness.In addition,the variation amplitude of the adjacent peak and valley on the curve of the content of the mean grain-size and>40μm grain-size fraction was larger than 3.4μm and the content of >40μm grain-size fraction was larger than 2.0μm.Lastly,the length of the variation time was less than 500 years.If all these criteria were met,the event was viewed as an abrupt event.

  15. Geochemistry of Carboniferous low metamorphic grade sedimentary and tholeiitic igneous rocks in the western Acatlán complex, southern Mexico: deposition along the active western margin of Pangea

    National Research Council Canada - National Science Library

    Ortega Obregón, Carlos; Duncan Keppie, J; Brendan Murphy, J


    Low grade metasedimentary rocks in the western Acatlán complex (Olinalá area) of southern Mexico occur in two units termed here the Progreso and Zumpango units of Lower and middle Carboniferous ages, respectively...

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


    Grant M. Young


    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 tempera...

  17. SITE-94. Glaciation and regional ground-water flow in the Fennoscandian shield

    Energy Technology Data Exchange (ETDEWEB)

    Provost, A.M.; Voss, C.I.; Neuzil, C.E. [US Geological Survey, Reston, VA (United States)


    Results from a regional-scale ground-water flow model of the Fennoscandian shield suggest that ground-water flow is strongly affected by surface conditions associated with climatic change and glaciation. The model was used to run a series of numerical simulations of variable-density ground-water flow in a 1500-km-long and approximately 10-km-deep cross-section that passes through southern Sweden. Ground-water flow and shield brine transport in the cross-sectional model are controlled by an assumed time evolution of surface conditions over the next 140 ka. The simulation results suggest that vertical movement of deep shield brines induced by the next few glacial cycles should not increase the concentration of dissolved solids significantly above present-day levels. However, the concentration of dissolved solids should decrease significantly at depths of up to several kilometers during periods of glacial melt water recharge. The melt water may reside in the subsurface for periods exceeding 10 ka and may bring oxygenated conditions to an otherwise reducing chemical environment 33 refs, 32 figs, 4 tabs

  18. Presumable incipient hybrid speciation of door snails in previously glaciated areas in the Caucasus. (United States)

    Koch, Eva L; Neiber, Marco T; Walther, Frank; Hausdorf, Bernhard


    Homoploid hybrid speciation, speciation by hybridization without a change in chromosome number, may be the result of an encounter of closely related species in a habitat that is different from that usually occupied by these species. In the northwestern Caucasus the land snail species Micropontica caucasica and M. circassica form two distinct entities with little admixture at low and intermediate altitudes. However, at higher altitudes in the Lagonaki plateau, which were repeatedly glaciated, Micropontica populations with intermediate characters occur. Admixture analyses based on AFLP data demonstrated that the populations from the Lagonaki plateau are homoploid hybrids that now form a cluster separate from the parental species. The Lagonaki populations are characterized by a mtDNA haplotype clade that has been found in the parental species only once. The fixation of this haplotype clade in most hybrid populations suggests that these haplotypes are better adapted to the cooler conditions in high altitude habitats and have replaced the haplotypes of the parental species in a selective sweep. The fixation of a presumably adaptive mitochondrial haplotype clade in the Lagonaki populations is an important step towards speciation under the differential fitness species concept.

  19. Sea level fall during glaciation stabilized atmospheric CO2 by enhanced volcanic degassing (United States)

    Hasenclever, Jörg; Knorr, Gregor; Rüpke, Lars H.; Köhler, Peter; Morgan, Jason; Garofalo, Kristin; Barker, Stephen; Lohmann, Gerrit; Hall, Ian R.


    Paleo-climate records and geodynamic modelling indicate the existence of complex interactions between glacial sea level changes, volcanic degassing and atmospheric CO2, which may have modulated the climate system's descent into the last ice age. Between ~85 and 70 kyr ago, during an interval of decreasing axial tilt, the orbital component in global temperature records gradually declined, while atmospheric CO2, instead of continuing its long-term correlation with Antarctic temperature, remained relatively stable. Here, based on novel global geodynamic models and the joint interpretation of paleo-proxy data as well as biogeochemical simulations, we show that a sea level fall in this interval caused enhanced pressure-release melting in the uppermost mantle, which may have induced a surge in magma and CO2 fluxes from mid-ocean ridges and oceanic hotspot volcanoes. Our results reveal a hitherto unrecognized negative feedback between glaciation and atmospheric CO2 predominantly controlled by marine volcanism on multi-millennial timescales of ~5,000-15,000 years.

  20. Fan type end moraine related glaciofluvial deposits of Last Glaciation from Lithuania (United States)

    Šinkūnė, Eglė; Šinkūnas, Petras


    Several alluvial-fan type end moraine related sites were chosen for detailed sedimentological analyses in ice marginal zone of the last glaciation in Lithuania. Such glaciofluvial ice-marginal fans are formed close to linear ice-sheet front and have semi-conical form or represent simple asymmetric hill forms or more complex ridges with steep proximal and gentler distal slopes. Sedimentary sequences of ice-marginal fans studied consist mainly of waterlain sandy and gravelly deposits with pebbles and boulders. In some sequences a debris-flow deposits are observed as well as beds of sorted material interbedded with dominating high energy sheetflow deposits. Sediment grain size, sorting, structure and bedding characteristics dependent on ice proximity and hydrodynamic conditions were analysed. Highly pulsatory water discharge can be interpreted from depositional architecture of the end moraine related fans. The inferred character of sedimentation suggests that landforms consisting of deposits studied are genetically similar to the alluvial fans. According to the sedimentation features the investigated landforms are an intermediate between the marginal glaciofluvial ridges and sandur fans. Are they a transition zone of sedimentation between the end moraines and proximal outwash plains, or can be the end moraine related fans distinguished as a separate type of glaciofluvial deposits? This question is still open.

  1. Cloud glaciation temperature estimation from passive remote sensing data with evolutionary computing (United States)

    Carro-Calvo, L.; Hoose, C.; Stengel, M.; Salcedo-Sanz, S.


    The phase partitioning between supercooled liquid water and ice in clouds in the temperature range between 0 and -37°C influences their optical properties and the efficiency of precipitation formation. Passive remote sensing observations provide long-term records of the cloud top phase at a high spatial resolution. Based on the assumption of a cumulative Gaussian distribution of the ice cloud fraction as a function of temperature, we quantify the cloud glaciation temperature (CGT) as the 50th percentile of the fitted distribution function and its variance for different cloud top pressure intervals, obtained by applying an evolutionary algorithm (EA). EAs are metaheuristics approaches for optimization, used in difficult problems where standard approaches are either not applicable or show poor performance. In this case, the proposed EA is applied to 4 years of Pathfinder Atmospheres-Extended (PATMOS-x) data, aggregated into boxes of 1° × 1° and vertical layers of 5.5 hPa. The resulting vertical profile of CGT shows a characteristic sickle shape, indicating low CGTs close to homogeneous freezing in the upper troposphere and significantly higher values in the midtroposphere. In winter, a pronounced land-sea contrast is found at midlatitudes, with lower CGTs over land. Among this and previous studies, there is disagreement on the sign of the land-sea difference in CGT, suggesting that it is strongly sensitive to the detected and analyzed cloud types, the time of the day, and the phase retrieval method.

  2. Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment. (United States)

    Vijayakumar, S P; Menezes, Riya C; Jayarajan, Aditi; Shanker, Kartik


    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.

  3. Ecology of red swamps in the glaciated northeast: a community profile (United States)

    Golet, Francis C.; Calhoun, Aram J. K.; DeRagon, William R.


    This report is part of a series of profiles on the ecology of wetland and deepwater habitats. This particular profile addresses red maple swamps in the glaciated northeastern United States. Red maple (Acer rubrum) swamp is a dominant wetland type in most of the region; it reaches its greatest abundance in southern New England and northern New Jersey, where it comprises 60-800/o of all inland wetlands. Red maple swamps occur in a wide variety of hydrogeologic settings, from small, isolated basins in till or glaciofluvial deposits to extensive wetland complexes on glacial lake beds, and from hillside seeps to stream floodplains and lake edges. Individual swamps may be seasonally flooded, temporarily flooded, or seasonally saturated, and soils may be mineral or organic. As many as five distinct vegetation layers may occur in these swamps, including trees, saplings, shrubs, herbs, and ground cover plants such as bryophytes and clubmosses. On a regional scale, red maple swamps support at least 50 species of trees, more than 90 species of shrubs and vines, and more than 300 species of nonwoody plants. These swamps also provide habitat for a rich faunal community, including several wetland-dependent species. In areas that are becoming urbanized, these wetlands often constitute critical habitat for facultative species as well. Red maple swamps also are important sites for flood storage, water quality improvement, recreation, scenic beauty, and open space.

  4. Early Paleozoic paleogeography of the northern Gondwana margin: new evidence for Ordovician-Silurian glaciation (United States)

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


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

  5. Climatic Consequences of Barents Ice Sheet Collapse During the Last Glaciation: Comparison With Other Release Locations (United States)

    Jones, C. L.; Bigg, G. R.


    An intermediate complexity climate model is used to simulate Henirich event-scale freshwater surges and fluxes of icebergs from the collapse of the Barents Ice Sheet during the last glaciation. The impact on convection and deep-water formation in the North Atlantic is compared to similar simulations from three other possible sources of icebergs: Hudson Strait, Gulf of St Lawrence and Norwegian Channel Ice Stream. We show that freshwater forcings and iceberg surges equivalent to 0.1 Sv from all release locations had a significant impact on the meridional overturning circulation, yet differences exist due to the time taken for icebergs to reach the North Atlantic, with the long trajectory of the European Icebergs resulted in a more gradual and delayed influx of meltwater, and a delayed return to previous conditions following the cessation of the influx. Whereas realistic iceberg surges from the Barents ice Sheet and NCIS do not halt the North Atlantic Meridional Overturning, it is halted for fluxes of 0.3 Sv from the Hudson Strait and Gulf of St Lawrence.

  6. Major advance of South Georgia glaciers during the Antarctic Cold Reversal following extensive sub-Antarctic glaciation (United States)

    Graham, Alastair G. C.; Kuhn, Gerhard; Meisel, Ove; Hillenbrand, Claus-Dieter; Hodgson, Dominic A.; Ehrmann, Werner; Wacker, Lukas; Wintersteller, Paul; Dos Santos Ferreira, Christian; Römer, Miriam; White, Duanne; Bohrmann, Gerhard


    The history of glaciations on Southern Hemisphere sub-polar islands is unclear. Debate surrounds the extent and timing of the last glacial advance and termination on sub-Antarctic South Georgia in particular. Here, using sea-floor geophysical data and marine sediment cores, we resolve the record of glaciation offshore of South Georgia through the transition from the Last Glacial Maximum to Holocene. We show a sea-bed landform imprint of a shelf-wide last glacial advance and progressive deglaciation. Renewed glacier resurgence in the fjords between c. 15,170 and 13,340 yr ago coincided with a period of cooler, wetter climate known as the Antarctic Cold Reversal, revealing a cryospheric response to an Antarctic climate pattern extending into the Atlantic sector of the Southern Ocean. We conclude that the last glaciation of South Georgia was extensive, and the sensitivity of its glaciers to climate variability during the last termination more significant than implied by previous studies.

  7. Discovery and Significance of Quaternary Glacial Vestiges in the Hexigten Area of the Southern Da Hinggan Mountains, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    SUN Hongyan; TIAN Mingzhong; WU Fadong; ZHANG Jianping


    The question whether there have been Quaternary glaciations in the Da Hinggan area has puzzled glacial geologists for many years because no sufficient glacial evidence has been found in this area. The study of Quaternary glaciers in the Da Hinggan area is also a key issue of the glaciology in China because of the special location of this area. In the past two years,a large number of complete and typical glacial vestiges have been found in Hexigten in the southern Da Hinggan Mountains,such as fossil cirque groups,horns,knife-edge crests,terminal moraines,glacial stepped stones.These landforms are located at a watershed,which are thus impossible to be formed due to tectonic processes,water or weathering,but can only be formed by glaciation. The calculated flat indexes of the fossil cirques in the Hexigten are 1.7-4.5,4-5 and 1.3-5,which are within the range of 1.7-5 that is the flat index of real cirques. The typical and complete moraines have also been found in this area. All these glacial vestiges prove that the Quaternary glaciers did exist in the Da Hinggan Mountains of eastern China. Thus,it is of important scientific significance for the research on Chinese,even the global climatic and environmental evolution since the Quaternary.

  8. Organic matter maturation vs clay mineralogy: A comparison for Carboniferous to Eocene sediments from the Alpine – Dinaride junction (Slovenia, Austria

    Directory of Open Access Journals (Sweden)

    Thomas Rainer


    Full Text Available Clay mineral diagenesis of Carboniferous to Paleogene rocks within the Alpine-Dinaric junction was studied and compared to vitrinite reflectance. Generally, there is a good fit between clay mineral diagenesis and VR. However, clay mineral alterations lag behindmaturation in some Ladinian and Carnian rocks (e.g. northern margin of the Dinaric Platform. Most probably, the lag in clay mineral diagenesis reflects an highly varying geochemical background in these stratigraphic horizons. Carboniferous deposits are late diagenetic to anchimetamorphic. Mesozoic deposits cover the range from middle diagenesis to the anchizone. Triassic to Cretaceous rocks in the SB and the Sava Folds reach the anchizone. Differences in diagenesis/metamorphism are mainly due to different maximumburial in Paleogene time.

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

    Zodrow, E.L.; Mastalerz, Maria


    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.

  10. Sedimentology, conodonts and ostracods of the Devonian - Carboniferous strata of the Anseremme railway bridge section, Dinant Basin, Belgium (United States)

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


    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

  11. Reconstruction of the Ice Age Glaciation in the Southern Slopes of Mt. Everest, Cho Oyu, Lhotse and Makalu (Himalaya) (Part 1)

    Institute of Scientific and Technical Information of China (English)

    Matthias Kuhle


    orographic snow-line. The number of the glacier stages since the maximum glaciation approx. agrees with that e.g. in the Alps and the Rocky Mountains since the last glacial period.Accordingly, it is interpreted as an indication of the margin positions. The current climatic, average glacier snow-line in the research area runs about 5500 m asl. The snow-line depression (ELA) of the has run about 3870 m asl, so that an ELA-depression of c. 1630 m has been determined. This corresponds to a lowering of the annual temperature by c. 8, i.e.,10℃ according to the specific humid conditions at that time.

  12. No evidence for post-icesheet cirque glaciation in New England (United States)

    Waitt, R.B.; Davis, P.T.


    New field data and scrutiny of past reports reveal no firm evidence that local cirque glaciers were rejuvenated after late Wisconsin continental ice disappeared from the northern Green Mountains of Vermont, Mount Katahdin in Maine, and the northern Presidential Range of New Hampshire. The sharpness of some cirques and aretes in New England is not reliable evidence that the cirques were last occupied by local glaciers, for even sharper cirques and aretes have survived overriding by icesheets in other regions. -from Authors

  13. Detrital zircon U-Pb geochronology and provenance of the Carboniferous-Permian glaciomarine pebbly slates in the Tibetan Plateau (United States)

    Wang, Q.; Zhu, D.; Zhao, Z.; Chung, S.; Li, C.; Sui, Q.; Fu, X.; Mo, X.


    Glaciomarine diamictites (including pebbly slate, pebbly siltstone, and pebbly sandstone) in the Tibetan Plateau are widely interpreted to have been associated with the deglaciation of the Indian continent. Guiding by zircon cathodoluminescence images, we determined U-Pb ages for detrital zircons from five typical Carboniferous-Permian pebbly slate samples from the Qiangtang, Lhasa, and Tethyan Himalaya of the Tibetan Plateau. The age distributions of detrital zircons from two samples (180 analyses) from Qiwu and Gangma Tso of the Qiangtang Terrane are similar, with two main age peaks ca. 579 and ca. 816 Ma and one minor age peak ca. 2490 Ma. Two samples (177 analyses) from Jiangrang and Damxung of the Lhasa Terrane define similar age distributions with two main age peaks ca. 539 and ca. 1175 Ma. Ages of detrital zircons from one sample (110 analyses) from Kangmar of the Tethyan Himalaya display main age peaks ca. 535, ca. 949, and ca. 2490 Ma. The ca. 816-Ma detrital zircons from the Qiangtang Terrane were most likely derived from the Lesser Himalaya, and the ca. 950-Ma detrital zircons from the Tethyan Himalaya might have been sourced from the High Himalaya, Eastern Ghats Province of the Indian plate and the Rayner Province of East Antarctica. The distinctive ca. 1175-Ma age population characteristic of zircons in the pebbly slates from the Lhasa Terrane is identical to the detrital zircons from the late Paleozoic sandstones (Zhu et al., 2011a) and the inherited zircons from the Mesozoic peraluminous granites (Zhu et al., 2011b) in this terrane, but significantly absent in the pebbly slates from both the Qiangtang and the Tethyan Himalayan terranes. The ca. 1175-Ma detrital zircons in the Lhasa Terrane were most likely sourced from the Albany-Fraser-Wilkes in southwestern Australia and East Antarctica. These new data obtained in this study reveal a distinct difference of detrital zircon provenance for the coeval Carboniferous-Permian glaciomarine pebbly slates

  14. Patient-centred mountain medicine. (United States)

    Szawarski, Piotr; Hillebrandt, David


    Venturing into the mountains, doctors have accompanied expeditions to provide routine care to the teams, undertake research and occasionally take on a rescue role. The role of doctors practicing mountain medicine is evolving. Public health issues involving concepts of health and safety have become necessary with the coming of commercial and youth expeditions. Increasingly individuals with a disability or a medical diagnosis choose to ascend to high altitudes. Doctors become involved in assessment of risk and providing advice for such individuals. The field of mountain medicine is perhaps unique in that acceptance of risk is part of the ethos of climbing and adventure. The pursuit of mountaineering goals may represent the ultimate conquest of a disability. Knowledge of mountain environment is essential in facilitating mountain ascents for those who choose to undertake them, in spite of a disability or medical condition.

  15. An integrative water balance model framework for a changing glaciated catchment in the Andes of Peru (United States)

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


    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

  16. HENDUAN MOUNTAINS A Dazzling World

    Institute of Scientific and Technical Information of China (English)


    The Indian Continent drifted northward and eventually collideawith the Euro-Asian Continent,pushing up the piece of land weknow today as the Himalayas and Henduan Mountains.Located where Qinghai,Tibet,Yunnan and Sichuan all meet.Asia,including the Nujiang,Jinshajiang and Lancanjiang.In the mountains,rivers Wave a drop of about 2,500 meters.Late last year,we drove into the mountainous area,covering adistance of some 1,000 km.

  17. Estimation of future glaciation and runoff in the Tanimas basin, Eastern Pamirs

    Directory of Open Access Journals (Sweden)

    W. Hagg


    Full Text Available A conceptual hydrological model was set up in the upper Panj catchment, the main tributary of Amu-Darya river. Driven by daily temperature and precipitation, the model reproduced daily hydrographs of Tanimas river at the Rukhk gauging station in a very satisfactory way. Based on two glacier inventories from the mid-20st century (WGI, World Glacier Inventory and from 2003 (GLIMS, Global Land Ice Measurements from Space, a simple parameterization scheme based on steady state conditions was applied to infer the ice volumes and glacier areas for the two different time periods in the past. Assuming temperature rises of 2.2 °C and 3.1 °C, which mark the extreme values of regional climate scenarios, the same method was used to extrapolate glaciation to the year 2050. The results show that these temperature rises will reduce the current glacier extent of 431 km2 by 36% and 45%, respectively. To assess future changes in water availability, the hydrological model input was modified according to the regional climate scenarios and the resulting glacier changes. The use of an elevation distributed deglaciation pattern is a clear improvement over methods used previously, where the impact on runoff was tested by excluding either the lower half or the total glacier area. The runoff scenarios reveal no changes in annual runoff, because the glacier area decrease is balanced out by enhanced melt rates. However, there is an important seasonal shift of water resources from summer to spring, unfavorably affecting agriculture and irrigation in the lowlands.

  18. Mount Meager Volcano, Canada: a Case Study for Landslides on Glaciated Volcanoes (United States)

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


    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.

  19. Sulfate exports from multiple catchments in a glaciated forested watershed in western New York, USA. (United States)

    Inamdar, Shreeram P; Mitchell, Myron J


    Sulfate (SO4(2-)) concentrations and fluxes were studied for multiple storm events in the Point Peter Brook watershed, a glaciated, forested watershed located in Western New York, USA. Investigations were performed across one large (696 ha) and three small (1.6-3.4 ha) catchments with varying extent of riparian and wetland areas. Concentrations of SO4(2-) in groundwater sources (mean values: 238-910 micromol(c) L(-1)) were considerably greater than concentrations recorded for rainfall (60 micromol(c) L(-1)) and throughfall (72-129 micromol(c) L(-1)). Seasonality in SO4(2-) concentrations was most pronounced for valley-bottom riparian waters with maximum concentrations in late winter-spring (February-March) and a minimum in late summer (August). Concentrations of SO4(2-) in wetland water were considerably less than riparian water indicating the likelihood of SO4(2-) reduction in anoxic wetland conditions. Storm events displayed a dilution pattern in SO4(2-) concentrations with a minimum coinciding with the maximum in throughfall contributions. End member mixing analysis (EMMA) was able to predict the storm event concentrations of SO4(2-) for four of the six comparisons. Concentrations of SO4(2-) at the outlet of the large (696 ha) catchment were much greater than values recorded for the smaller catchments. Exports of SO4(2-) in streamflow exceeded the inputs from atmospheric deposition suggesting that watersheds like Point Peter Brook may not show any immediate response to decreases in atmospheric SO4(2-) deposition.

  20. Coupled stratigraphic and structural evolution of a glaciated orogenic wedge, offshore St. Elias orogen, Alaska (United States)

    Worthington, Lindsay L.; Gulick, Sean P. S.; Pavlis, Terry L.


    The St. Elias orogen is the result of ˜10 Myr of oblique convergence and flat-slab subduction in the Gulf of Alaska between North America and the Yakutat microplate. Extensive glaciation and a complex tectonic environment make this region a unique case study in which to examine the details of terrane accretion and the possible coupled influence of climate and tectonic drivers on the structural and topographic evolution of an orogenic wedge. Reflection seismic profiles across the offshore Pamplona zone fold-thrust belt, the frontal St. Elias orogenic wedge, provide constraints for quantifying Pleistocene deformation recorded in the glaciomarine Yakataga formation. The total amount of Pleistocene shortening observed varies from ˜3 to 5 mm/yr, compared to the current GPS-derived Yakutat-North America convergence rate across the St. Elias orogen of ˜45 mm/yr. Growth strata and kinematic fold analysis allow comparison of relative timing of fault activity, which reveals temporal and spatial shifting of active deformation during the glacial period: faulting localized adjacent to the coastline and at the current submarine deformation front. The abandoned, currently inactive region is colocated with the major glacial depocenter in the region, the Bering Trough. These observations imply that glacial processes such as sediment loading and focused erosion during advance-retreat cycles has a direct effect on the evolution of individual faults within the Pamplona zone and the overall deformation pattern in the offshore St. Elias margin. This information provides key constraints for understanding how climatic shifts may have affected the evolution of margin architecture during Pleistocene glacial-interglacial periods.

  1. Ages and inferred causes of late Pleistocene glaciations on Mauna Kea, Hawai'i (United States)

    Pigati, J.S.; Zreda, M.; Zweck, C.; Almasi, P.F.; Elmore, D.; Sharp, W.D.


    Glacial landforms on Mauna Kea, Hawai'i, show that the summit area of the volcano was covered intermittently by ice caps during the Late Pleistocene. Cosmogen 36Cl dating of terminal moraines and other glacial landforms indicates that the last two ice caps, called Older Makanaka and Younger Makanaka, retreated from their maximum positions approximately 23ka and 13ka, respectively. The margins and equilibrium line altitudes of these ice caps on the remote, tropical Pacific island were nearly identical, which would seem to imply the same mechanism for ice growth. But modelling of glacier mass balance, combined with palaeotemperature proxy data from the subtropical North Pacific, suggests that the causes of the two glacial expansions may have been different. Older Makanaka airatop Mauna Kea was likely wetter than today and cold, whereas Younger Makanaka times were slightly warmer but significantly wetter than the previous glaciation. The modelled increase in precipitation rates atop Mauna Kea during the Late Pleistocene is consistent with that near sea level inferred from pollen data, which suggests that the additional precipitation was due to more frequent and/ or intense tropical storms associated with eastward-moving cold fronts. These conditions were similar to modern La Ni??a (weak ENSO) conditions, but persisted for millennia rather than years. Increased precipitation rates and the resulting steeper temperature lapse rates created glacial conditions atop Mauna Kea in the absence of sufficient cooling at sea level, suggesting that if similar correlations existed elsewhere in the tropics, the precipitation-dependent lapse rates could reconcile the apparent difference between glacial-time cooling of the tropics at low and high altitudes. Copyright ?? 2008 John Wiley & Sons, Ltd.

  2. Biogeochemical cycling in the Bering Sea over the onset of major Northern Hemisphere Glaciation (United States)

    Swann, George E. A.; Snelling, Andrea M.; Pike, Jennifer


    The Bering Sea is one of the most biologically productive regions in the marine system and plays a key role in regulating the flow of waters to the Arctic Ocean and into the subarctic North Pacific Ocean. Cores from Integrated Ocean Drilling Program (IODP) Expedition 323 to the Bering Sea provide the first opportunity to obtain reconstructions from the region that extend back to the Pliocene. Previous research at Bowers Ridge, south Bering Sea, has revealed stable levels of siliceous productivity over the onset of major Northern Hemisphere Glaciation (NHG) (circa 2.85-2.73 Ma). However, diatom silica isotope records of oxygen (δ18Odiatom) and silicon (δ30Sidiatom) presented here demonstrate that this interval was associated with a progressive increase in the supply of silicic acid to the region, superimposed on shift to a more dynamic environment characterized by colder temperatures and increased sea ice. This concluded at 2.58 Ma with a sharp increase in diatom productivity, further increases in photic zone nutrient availability and a permanent shift to colder sea surface conditions. These transitions are suggested to reflect a gradually more intense nutrient leakage from the subarctic northwest Pacific Ocean, with increases in productivity further aided by increased sea ice- and wind-driven mixing in the Bering Sea. In suggesting a linkage in biogeochemical cycling between the south Bering Sea and subarctic Northwest Pacific Ocean, mainly via the Kamchatka Strait, this work highlights the need to consider the interconnectivity of these two systems when future reconstructions are carried out in the region.

  3. Hydrological and temperature change in Arctic Siberia during the intensification of Northern Hemisphere Glaciation (United States)

    Keisling, Benjamin A.; Castañeda, Isla S.; Brigham-Grette, Julie


    The Pliocene epoch represents an analog for future climate, with atmospheric carbon dioxide concentrations and continental configurations similar to present. Although the presence of multiple positive feedbacks in polar regions leads to amplified climatic changes, conditions in the Pliocene terrestrial Arctic are poorly characterized. High latitude sedimentary records indicate that dramatic glacial advance and decay occurred in the Pliocene Arctic, with attendant effects on global sea-level. Understanding these deposits and their implications for Earth's future requires developing a sense of climatic evolution across the Pliocene-Pleistocene transition and during the intensification of Northern Hemisphere Glaciation (iNHG) ∼2.7 million yr ago (Ma). Here we reconstruct Arctic terrestrial environmental change from 2.82-2.41 Ma (Marine Isotope Stages (MIS) G10-95) using the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) and the isotopic composition of plant leaf waxes (δDwax) in a sedimentary archive from Lake El'gygytgyn, Northeast Russia. Our records reveal changes in proxy behavior across this interval that we attribute to changing boundary conditions, including sea level, sea ice, vegetation and pCO2 during different MISs. We find that brGDGT temperatures and δDwax are decoupled for most of the record, although both show an increasing range of glacial-interglacial variability following iNHG. δDwax is stable from MIS G10-G4 despite changes in vegetation and temperature, suggesting different sources or pathways for moisture to Lake El'gygytgyn during the Late Pliocene.

  4. 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


    fluctuations linked to the 100 k.y. Milankovitch cycle. The stratigraphic distribution of subaerial exposure surfaces indicates that during Late Carboniferous-Early Permian time, the northern Pangea shelf repeatedly changed from being a shallow subtropical carbonate platform to a vast subaerially exposed...

  5. Key issues for mountain areas

    National Research Council Canada - National Science Library

    Price, Martin F; Jansky, Libor; Iatsenia, Andrei A


    ... and livelihood opportunities . . . ... Safdar Parvez and Stephen F. Rasmussen 86 6 Mountain tourism and the conservation of biological and cultural diversity... Wendy Brewer Lama and Nikhat Sattar 11...

  6. A Breath of Mountain Air

    Institute of Scientific and Technical Information of China (English)



    Mountains are everywhere,and rivers flow in almost every valley.This is the Qinling Mountains,a major eastto-west range in southern Shaanxi Province,bordering Hubei and Henan provinces.Because of its huge forest coverage,the Qinling Mountains are also known as one of the lungs of China.Expectations for travelling are changing in China as the lifestyle of city dwellers has become fast-paced and demanding.That provides the Qirding Mountain area a great opportunity to develop leisure tourism.

  7. Redescription and phylogenetic relationships of Solenodonsaurus janenschi Broili, 1924, from the Late Carboniferous of Nýřany, Czech Republic

    Directory of Open Access Journals (Sweden)

    M. Danto


    Full Text Available The basal tetrapod Solenodonsaurus janenschi Broili, 1924, from Nýřany (Westphalian D, Late Carboniferous, Czech Republic, is redescribed and its phylogenetic position reevaluated. A distinct groove at the base of the maxillary teeth is regarded as an autapomorphic character, which is present in both the large and small specimens. Other characteristic features, which are not unique to S. janenschi, are: an extension of the lacrimal that forms the anteroventral margin of the orbit; a long posterior extension of the jugal; spool-shaped vertebrae, and small, wedge-like intercentra. A phylogenetic analysis based on the data matrix of Ruta, Coates and Quicke suggests that S. janenschi is the sister taxon of the Lepospondyli. Shared characters include the shape of the vertebrae, non-swollen neural arches, and absence of an intertemporal. Although nested within the amniote stem, S. janenschi is not as closely related to basal amniotes as previously suggested. A rather long, slender humerus argues for a predominantly terrestrial mode of life, and the curved, slender ribs, as well as the comparatively small skull, suggest costal ventilation of the lungs similar to that in amniotes, rather than buccal pumping. The morphology of the shallow squamosal embayment in which an ossified dorsal margin is absent, renders the presence of a tympanum unlikely. doi:10.1002/mmng.201200003

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

    Directory of Open Access Journals (Sweden)

    Gediminas Motuza


    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.

  9. 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.


    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.

  10. CYP1A2 phenotype and genotype in a population from the Carboniferous Region of Coahuila, Mexico. (United States)

    Castorena-Torres, Fabiola; Mendoza-Cantú, Ania; de León, Mario Bermúdez; Cisneros, Bulmaro; Zapata-Pérez, Omar; López-Carrillo, Lizbeth; Salinas, Juan E; Albores, Arnulfo


    CYP1A2 regulation by polycyclic aromatic hydrocarbons (PAHs) exposure and polymorphism was investigated in 46 male volunteers from the Carboniferous Region in northern Coahuila, Mexico. PAH exposure was estimated by the urinary excretion of 1-hydroxypyrene (1-OHP), whereas the regulatory effects were assessed by the caffeine metabolic ratio (CMR). Genotype was evaluated by determining 5'-flanking region (-2964) and intron I (734) polymorphisms. A statistically significant difference in the urinary 1-OHP geometric means of Barroterán, Cloete and Juárez (2.30, 0.45 and 0.04, respectively) was observed. As for the genotype, the intron I distribution was 0% C/C, 46% C/A and 54% A/A, whereas that of the 5'-flanking region was 26% G/G, 42% G/A and 32% A/A. Both distributions were in agreement with the Hardy-Weinberg equilibrium model. A greater enzyme activity was observed in the A/A compared to C/A individuals according to the CMR (P<0.001), whereas the 5'-flanking region polymorphism showed no effect on CYP1A2 enzymatic activity. These results suggest that intron I polymorphism and PAH exposure are relevant factors that modulate CYP1A2 enzymatic activity.

  11. Late Carboniferous palaeobotany of the upper Bideford Formation, north Devon: a coastal setting for a Coal Measures flora

    Energy Technology Data Exchange (ETDEWEB)

    Cleal, C.J.; Thomas, B.A. [Natural Museums & Galleries Wales, Cardiff (United Kingdom)


    The Culm Seams are thin coals in the Upper Carboniferous upper Bideford Formation of north Devon. Clastic sedimentary rocks associated with the coals have yielded a fossil macroflora dominated by the remains of the Calamostachyales and Medullosales, together with subsidiary lycophytes, sphenophylls, ferns, lagenostomaleans, rare cordaites, and a possible early cycad. The flora is probably early Langsettian in age, which is in agreement with the evidence of the non-marine bivalves and marine bands. It is broadly similar in composition to contemporaneous macrofloras from South Wales. It is unlikely to represent an assemblage formed from plant remains subject to long-distance transportation. Rather, it was probably preserved in the lower reaches of a 'bird-foot' delta that had temporarily transgressed into the Culm Basin. The distal margin of this delta would represent a comparable habitat to the levees of the rivers further inland, and thus would have supported vegetation similar to that which generated the more usual Coal Measures macrofloras.

  12. Correlation of Upper Devonian and Lower Carboniferous Depositional Sequences in Different Facies Belts on Southern Margin of Upper Yangtze Platform

    Institute of Scientific and Technical Information of China (English)


    A fundamental problem in sequence stratigraphy is whether the sequences are global in extent and whether the sea level changes are eustatic in nature. Study on the Upper Devonian and Lower Carboniferous depositional sequences in different facies belts on the southern margin of the Upper Yangtze platform shows that different orders of sequences possess distinctive distribution and correlation in space, although the sea level changes in various orders of sequences may be primarily global in nature. The present paper regards the distribution in space, especially in different facies belts, as a criterion for defining and recognizing the various orders of sequences. The orthosequence (third-order sequence) is probably global in nature, which may be discerned in various depositional facies belts on the continental margin and can be correlated over long distances, sometimes maybe worldwide. Commonly, correlation of the subsequences (fourth-order sequences with time interval of 0.5 Ma to 1.5 Ma) is difficult in different facies belts, although some of them are probably also worldwide in distribution. A subsequence should be distinguishable and correlatable within at least one facies belt. The higher-order sequences, including parasequences (fifth-order sequences) and microsequences (sixth-order sequences), are regional or local in distribution. They may have reflected the longer and shorter Milankovitch cycles respectively. Orthosequences and subsequences are usually recognizable in different facies belts, while parasequences and microsequences may be distinguished only in shallow marine deposits, but not in slope and basin facies deposits.

  13. Geochemical Characteristics and Genesis of Late Cretaceous to Paleogene Basalts in the Tuyon Basin, South Tianshan Mountains

    Institute of Scientific and Technical Information of China (English)

    WANG Yanbin; WANG Yong; LIU Xun; FU Derong; XIAO Xuchang; QI Longshui


    The Tianshan Mountains is believed to be a typical intercontinental mountain belt, which is formed during the tectonic amalgamation of the Tarim and Tianshan blocks and the Siberian carton in Late Carboniferous-Permian period. A series of basaltic extrusive and intrusive units emplaced primarily into the Late Cretaceous-Paleogene sedimentary rocks in the Tuyon basin and its adjacent area, the South Tianshan Mountains. Geochemical data of the basalts show low Sr and Pb isotopic values and relative high Nd values (87Sr/86Sr = 0.703554 ~ 0.703884; 143Nd/144Nd = 0.512838 ~ 0.512904;206pb/204pb = 18.0063 ~ 18.4720; 207pb/204pb = 15.5060; 208Pb/204P b= 37.8072~37.9290). The data of major elements, trace elements and rare earth elements of the basalts indicate that these basaltic rocks are similar to those beneath the Hawaiian Islands. In the Tuyon basin and its adjacent areas, some Cenozoic alkaline basaltic magmatism may be related to the Cenozoic activity of mantle plume.

  14. Properties of soils in Grove Mountains, East Antarctica

    Institute of Scientific and Technical Information of China (English)

    LI; Xiaoli(李潇丽); LIU; Xiaohan(刘小汉); JU; Yitai(琚宜太); HUANG; Feixin(黄费新)


    Three cold desert soil sites were first found in the southern Mount Harding, GroveMountains, East Antarctica. The soils are characteristics of the widespread occurrence of surfacedesert pavement, abundant water-soluble salts, strongly stained upper portion of soil profile,slightly acid and negligible organic matter content. A 1:5 soil-water extracts analysis indicates thatthe dominant cations are Mg2+ and Na+, followed by Ca2+ and K+, and the main anion is SO42-, thenCl- and NO-3. The accumulation of water-soluble salts indicates ion transportation in the frigid andarid Antarctica environment. The distribution of the salts is related to the maximum content ofmoisture and clay mineral. Clay fraction migration occurs in the soils, which is different from that ofother cold desert soils. The upper horizons of some profiles are generally stained, namely rubifica-tion, primarily because of the weathering of iron-bearing minerals. The reddish hues of cold desertsoils have been attributed to relatively high concentrations of dithionite-extractable Fe (Fed). Theweathering features of soils suggest that the soil age of this area is 0.5-3.5 Ma. No remnants ofglaciations were found on the soil sites of Mount Harding, which suggests that the Antarctic glaci-ations have not reached the soil sites since at least 0.5 Ma, even during the Last Glacial Maxi-mum.

  15. "Christ is the Mountain"

    Directory of Open Access Journals (Sweden)

    Carl Hallencreutz


    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.

  16. Human impacts to mountain streams (United States)

    Wohl, Ellen


    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

  17. mitochondrion Spermophilus musicus (Caucasian mountain ground [

    Lifescience Database Archive (English)

    Full Text Available mitochondrion Spermophilus musicus (Caucasian mountain ground [gbrod]: 2 CDS's (760... of codon usage for each CDS (format) Homepage mitochondrion Spermophilus musicus (Caucasian mountain ground ...

  18. Mountains and Tropical Circulation (United States)

    Naiman, Z.; Goodman, P. J.; Krasting, J. P.; Malyshev, S.; Russell, J. L.; Stouffer, R. J.


    Observed tropical convection exhibits zonal asymmetries that strongly influence spatial precipitation patterns. The drivers of changes to this zonally-asymmetric Walker circulation on decadal and longer timescales have been the focus of significant recent research. Here we use two state-of-the-art earth system models to explore the impact of earth's mountains on the Walker circulation. When all land-surface topography is removed, the Walker circulation weakens by 33-59%. There is a ~30% decrease in global, large-scale upward vertical wind velocities in the middle of the troposphere, but only minor changes in global average convective mass flux, precipitation, surface and sea-surface temperatures. The zonally symmetric Hadley circulation is also largely unchanged. Following the spatial pattern of changes to large-scale vertical wind velocities, precipitation becomes less focused over the tropics. The weakening of the Walker circulation, but not the Hadley circulation, is similar to the behavior of climate models during radiative forcing experiments: in our simulations, the weakening is associated with changes in vertical wind velocities, rather than the hydrologic cycle. These results indicate suggest that mountain heights may significantly influence the Walker circulation on geologic time scales, and observed changes in tropical precipitation over millions of years may have been forced by changes in tropical orography.

  19. Protected areas in mountains

    Directory of Open Access Journals (Sweden)

    Hamilton, L. S.


    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

  20. 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


    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)

  1. Assessment and application of a snowblow modelling approach for identifying enhanced snow accumulation in areas of former glaciation (United States)

    Mills, Stephanie; Smith, Michael; Le Brocq, Anne; Ardakova, Ekaterina; Hillier, John; Boston, Clare


    The redistribution of snow by wind can play an important role in providing additional mass to the surface of glaciers and can, therefore, have an impact on the glacier's surface mass balance. In areas of marginal glaciation, this local topo-climatic effect may be prove crucial for the initiation and survival of glaciers, whilst it can also increase heterogeneity in the distribution of snow on ice caps and ice sheets. We present a newly developed snowblow model which calculates spatial variations in relative snow accumulation that result from variations in topography. We apply this model to areas of former marginal glaciation in the Brecon Beacons, Wales and an area of former plateau icefield glaciation in the Monadhliath, Scotland. We can then determine whether redistribution by snow can help explain variations in the estimated equilibrium line altitudes (ELAs) of these former glaciers. Specifically, we compare the areas where snow is modelled as accumulating, to the reconstructed glacier surface, which is based on mapped moraines believed to be of Younger Dryas age. The model is applied to 30 m resolution DEMs and potential snow accumulation is simulated from different wind directions in order to determine the most likely contributing sector. Total snow accumulation in sub-set areas is then calculated and compared to the reconstructed glacier area. The results suggest that areas with larger amounts of snow accumulation often correspond with those where the ELA is lower than surrounding glaciers and vice versa, in both the marginal and icefield setting, suggesting that the role of snowblow in supplying additional mass to the surface of glaciers is significant.

  2. Robust Adaptation Research in High Mountains: Integrating the Scientific, Social, and Ecological Dimensions of Glacio-Hydrological Change

    Directory of Open Access Journals (Sweden)

    Graham McDowell


    Full Text Available Climate-related changes in glacierized watersheds are widely documented, stimulating adaptive responses among the 370 million people living in glacier-influenced watersheds as well as aquatic and riparian ecosystems. The situation denotes important interdependencies between science, society, and ecosystems, yet integrative approaches to the study of adaptation to such changes remain scarce in both the mountain- and non-mountain-focused adaptation scholarship. Using the example of glacio-hydrological change, it is argued here that this analytical limitation impedes the identification, development, and implementation of “successful” adaptations. In response, the paper introduces three guiding principles for robust adaptation research in glaciated mountain regions. Principle 1: Adaptation research should integrate detailed analyses of watershed-specific glaciological and hydro-meteorological conditions; glacio-hydrological changes are context-specific and therefore cannot be assumed to follow idealized trajectories of “peak water”. Principle 2: Adaptation research should consider the complex interplay between glacio-hydrological changes and socio-economic, cultural, and political conditions; responses to environmental changes are non-deterministic and therefore not deducible from hydrological changes alone. Principle 3: Adaptation research should be attentive to interdependencies, feedbacks, and tradeoffs between human and ecological responses to glacio-hydrological change; research that does not evaluate these socio-ecological dynamics may lead to maladaptive adaptation plans. These principles call attention to the linked scientific, social, and ecological dimensions of adaptation, and offer a point of departure for future climate change adaptation research in high mountains.

  3. Last glacial maximum climate inferences from cosmogenic dating and glacier modeling of the western Uinta ice field, Uinta Mountains, Utah (United States)

    Refsnider, Kurt A.; Laabs, Benjamin J. C.; Plummer, Mitchell A.; Mickelson, David M.; Singer, Bradley S.; Caffee, Marc W.


    During the last glacial maximum (LGM), the western Uinta Mountains of northeastern Utah were occupied by the Western Uinta Ice Field. Cosmogenic 10Be surface-exposure ages from the terminal moraine in the North Fork Provo Valley and paired 26Al and 10Be ages from striated bedrock at Bald Mountain Pass set limits on the timing of the local LGM. Moraine boulder ages suggest that ice reached its maximum extent by 17.4 ± 0.5 ka (± 2σ). 10Be and 26Al measurements on striated bedrock from Bald Mountain Pass, situated near the former center of the ice field, yield a mean 26Al/ 10Be ratio of 5.7 ± 0.8 and a mean exposure age of 14.0 ± 0.5 ka, which places a minimum-limiting age on when the ice field melted completely. We also applied a mass/energy-balance and ice-flow model to investigate the LGM climate of the western Uinta Mountains. Results suggest that temperatures were likely 5 to 7°C cooler than present and precipitation was 2 to 3.5 times greater than modern, and the western-most glaciers in the range generally received more precipitation when expanding to their maximum extent than glaciers farther east. This scenario is consistent with the hypothesis that precipitation in the western Uintas was enhanced by pluvial Lake Bonneville during the last glaciation.

  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.


    migration into Europe from a proposed Asian origin. However, the strong geographic pattern in the genetic structure, pronounced isolation by distance (R2 = 0.74) and moderate overall population differentiation (FST = 0.13) suggests high historical gene flow, possibly during glacials, and vicariance...... not agree with the expectations from east–west migration into Europe. Furthermore, managed habitats showed higher levels of genetic diversity compared to unmanaged habitats. Stepwise linear regression determined shoot density and soil phosphorus as the main predictors of within-population genetic diversity...... by post-glacial vicariance while patterns of genetic diversity seemed mainly to be influenced by human land use. Our findings highlight the importance of applying a synthetic approach, testing the influence of both historical and contemporary processes on genetic structure and diversity in order...


    Energy Technology Data Exchange (ETDEWEB)



    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.

  6. Surface reconstruction and derivation of erosion rates over several glaciations (1 Ma) in an alpine setting (Sinks Canyon, Wyoming, USA) (United States)

    Züst, Fabian; Dahms, Dennis; Purves, Ross; Egli, Markus


    At middle to high latitudes, many alpine valleys have been shaped by glaciers associated with periods of Pleistocene glaciation. Present glaciated valleys are characterised by broadened valley floors and U-shaped cross sections, continuously formed by glacial activity from initially V-shaped, fluvial cross sections. Sinks Canyon (Wind River Range, USA) is a glaciated valley characterised by a typical U-shaped cross section, containing till from several glacial advances over a range of at least 1 Ma. The morphostratigraphic records indicate a fourfold difference in ice surface elevation between the youngest and oldest glacial periods, which is not easily explained by the present-day valley topography. To assess possible evolution scenarios of Sinks Canyon, we modelled the palaeovalley topography using a geographic information system (GIS) filtering technique in combination with temporal reference points from relative and numerically dated glacial deposits. Ice thicknesses were calculated using the shallow ice approximation. In our model, the valley became shallower and the topography smoother with increasing years back in time. The results suggest that valley topography with ages between 640 and 1000 ka can clearly be distinguished from the present-day topography. Surfaces with ages of 130-200 ka (attributable to MIS 6; Bull Lake glaciation) still could be discerned from present-day topography, but with relatively high uncertainties. The method did not work for topography less than ~ 100 ka or older than ~ 1 Ma. Erosion depths were calculated using the differences between present-day elevation and the modelled surfaces. Calculated erosion rates were within the range of reference values for glacial erosion (0.001 to 1 mm a- 1). Glacial erosion appears to have removed 0.52 to 0.72 mm a- 1 of rock within a time frame of 1 Ma, assuming 200 ka of aggregated glacial flow. If the glacial occupation was longer or the impact of fluvial erosion was not negligible (as assumed

  7. 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


    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

  8. Geophysical Identification of Filled Sinkholes and Buried Fractures in Glaciated Karst (United States)

    Carpenter, P. J.


    Karst aquifers are highly susceptible to contamination, with numerous points of entry for contaminants through recharge features such as sinkholes, swallow holes and soil pipes. These recharge features may be filled or obscured at the surface, requiring the use of geophysical techniques or remote sensing for their identification. This problem is particularly acute in recently glaciated terrain, where surface topography is often unrelated to underlying active karst features, as illustrated by three Illinois examples in this study. Approximately 10 km south of Rockford, IL, a network-type cave of interconnected solutionally-enlarged fractures extends over an area of approximately 1 ha, beneath a low Ordovician dolomite ridge covered with approximately 5 m of glacial till and outwash. Ground-penetrating radar (GPR) profiles along the ridge top, utilizing 50 and 100 MHz antennas, showed strong diffractions over unsaturated caves and karst conduits. A trough-like feature approximately 20 m wide and 3 m deep was also identified in GPR profiles approximately 20 m west of the mapped cave passages. It probably represents an elongate filled sinkhole, similar to those observed along the wall of a quarry less than 1 km west of the cave. GPR profiles and two-dimensional electrical resistivity imaging identified clay-filled sinkholes 2-3 m wide and about 3 m deep in Bourbonnais, IL, 100 km south of Chicago, where 1 to 4 meters of loess and till overlie karstic Silurian dolomite. Penetrometer surveys revealed deeply weathered bedrock zones containing vertical clay-filled caves beneath the filled sinkholes. Surface water infiltration estimates are being made for these features, utilizing the geophysically-derived geometries, along with hydraulic conductivity and gradient data. EM conductivity profiles were combined with resistivity soundings at landfill in southern Illinois near St. Louis, where approximately 5 m of till overlies karstic limestone. Linear high conductivity

  9. Woolly mammoth ( Mammuthus primigenius Blum.) and its environment in northern Europe during the last glaciation (United States)

    Ukkonen, P.; Aaris-Sørensen, K.; Arppe, L.; Clark, P. U.; Daugnora, L.; Lister, A. M.; Lõugas, L.; Seppä, H.; Sommer, R. S.; Stuart, A. J.; Wojtal, P.; Zupiņš, I.


    Woolly mammoths were large, herbivorous, cold-adapted mammals of the Late Pleistocene. The diet and habitat requirements of the species set certain constraints on the palaeoenvironments it could occupy. The relationship between the mammoth's shifting range and changing environments can be explored using independent data on ice sheet configuration, temperature, and vegetation, provided the locality and age of the fossil remains can be validated. Here we present a comprehensive record of occurrence of the woolly mammoth in the circum-Baltic region of northern Europe during the last glaciation, based on a compilation of radiocarbon-dated remains. The record shows that the mammoth was widespread in northern and north-eastern Europe during Marine Isotope Stage 3 (MIS 3), at 50,000-30,000 calibrated years ago (50-30 ka). The presence of the species up to 65°N latitude supports the restriction of the Scandinavian Ice Sheet (SIS) during MIS 3. The widest distribution range round 30 ka was followed by a decline that led to the disappearance of mammoths from the area during the maximum extent of the SIS, from 22 to 18 ka. The woolly mammoth re-colonized the Baltic region and southern Scandinavia after the onset of the late-glacial deglaciation at 17 ka. The late-glacial record suggests a markedly fluctuating population changing its range in tune with the rapid environmental changes. The last appearance of mammoth in our study region was in Estonia during the Younger Dryas (Greenland Stadial 1; GS1) at about 12 ka. The two major periods of occurrence during MIS 3 and the late-glacial stadial suggest that mammoth had a wide tolerance of open to semi-open tundra and steppe-tundra habitats with intermediately cold climate, whereas the 22-18 ka disappearance suggests a major southward and/or eastward retreat in response to extremely cold, glacial conditions near the SIS margin. The final regional extinction correlates with the re-forestation during the rapid warming at the

  10. Holocene depositional history of a large glaciated estuary, Penobscot Bay, Maine (United States)

    Knebel, H. J.


    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 (Graded sediments within this stratum began to accumulate early in the transgression, and they record both the decrease in 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

  11. Cosmogenic 10Be and 26Al exposure ages of glaciations in the Frankland Range, southwest Tasmania reveal a limited MIS-2 ice advance (United States)

    Kiernan, Kevin; Fink, David; McConnell, Anne


    New mapping of the glacial geomorphology coupled with 10Be and 26Al exposure age dating of moraines on the flanks of the Frankland Range in south west Tasmania indicate that glacier extent during MIS-2 was far smaller than during earlier glaciations with the ice cover being confined to only the uppermost cirques of the range. Moraines further down the range flanks, ∼50-150 m lower in altitude than the MIS-2 dated advance, indicate that glaciers were only slightly larger during earlier glaciations and, depending on the interpretation of their exposure ages, may range from MIS 7 to MIS 12. These older moraines are nested inside the maximum ice limits of an even more ancient and extensive glaciation, defined by degraded valley floor moraines and coalescing glacio-fluvial fans that remain undated but appear no younger than MIS 12. Patterns of glacial erosion and moraine deposition on the Frankland Range suggest that the more recent glaciations were increasingly influenced by the erosional morphology initiated by earlier glaciers. Microclimatic differences resulting from this earlier glacial topography were particularly influential determinants of glaciation during MIS 2. These results are consistent with emerging evidence from studies of other ranges in southwest Tasmania.

  12. European mountain biodiversity

    Directory of Open Access Journals (Sweden)

    Nagy, Jennifer


    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

  13. 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.

  14. 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


    Full Text Available Strong 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.

  15. 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


    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.

  16. A New Paleozoic Symmoriiformes (Chondrichthyes) from the Late Carboniferous of Kansas (USA) and Cladistic Analysis of Early Chondrichthyans (United States)

    Pradel, Alan; Tafforeau, Paul; Maisey, John G.; Janvier, Philippe


    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. PMID:21980367

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

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


    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.

  18. ROBUST hot wire probe efficiency for total water content measurements in glaciated conditions (United States)

    Leroy, Delphine; Lilie, Lyle; Weber, Marc; Schwarzenboeck, Alfons; Strapp, J. Walter


    During the two High Altitude Ice Crystals (HAIC, Dezitter et al. 2013)/High Ice Water Content (HIWC, Strapp et al., 2016a) international flight campaigns that investigated deep convection in the tropics, the French Falcon 20 research aircraft was equipped with two different devices measuring the Total Water Content (TWC): - the IKP-2 (Isokinetic Probe, Davison et al. 2008, 2016), - and the hot wire ROBUST probe (Strapp et al. 2008; Grandin et al. 2014). The IKP-2 probe is an evaporator that has been specifically designed to measure high ice water content (Strapp et al. 2016b) with a collection efficiency near unity. It has undergone extensive performance assessment in liquid and glaciated conditions in several wind tunnels. The Robust probe was initially developed by Science Engineering Associates to estimate high ice water content in a high speed wind tunnel, in harsh conditions where other hot-wires had been observed to suffer failures. It was known at the outset that, like other hot-wire TWC probes, it would measure only a quasi-constant fraction of the true ice water content. Early wind tunnel and flight experience with the ROBUST probe revealed that this fraction was the order of 40% for ice crystals. During the HAIC/HIWC campaigns (Leroy et al. 2016, 2017), supercooled liquid water conditions were documented according to a detailed analysis of a Rosemount Ice detector (RICE) and a Cloud Droplet Probe (CDP) measurements, and were found to be rare. Thus, the HAIC/HIWC dataset represents a unique opportunity to study in more detail the ROBUST efficiency in glaciated conditions, using the IKP-2 values as a comparative reference. Comparison of IKP-2 and ROBUST measurements will show that the ROBUST behavior differs between low (below 1.5 g/m3) and high (above 2 g/m3) ice content conditions and is also sensitive to temperature. The sensitivity of the ROBUST collection efficiency to ice particles size could also be explored as optical imaging probes were part of the

  19. 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)


    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

  20. Geology at Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)



    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.

  1. Iron Mountain Electromagnetic Results

    Energy Technology Data Exchange (ETDEWEB)

    Gail Heath


    Iron Mountain Mine is located seventeen miles northwest of Redding, CA. After the completion of mining in early 1960s, the mine workings have been exposed to environmental elements which have resulted in degradation in water quality in the surrounding water sheds. In 1985, the EPA plugged ore stoops in many of the accessible mine drifts in an attempt to restrict water flow through the mine workings. During this process little data was gathered on the orientation of the stoops and construction of the plugs. During the last 25 years, plugs have begun to deteriorate and allow acidic waters from the upper workings to flow out of the mine. A team from Idaho National Laboratory (INL) performed geophysical surveys on a single mine drift and 3 concrete plugs. The project goal was to evaluate several geophysical methods to determine competence of the concrete plugs and orientation of the stopes.

  2. Microfacies and Environment Analysis of the Carboniferous Carbonates in Jiangyou-Guangyuan Area, Sichuan Province%四川江油—广元地区上石炭统碳酸盐岩微相及其沉积环境分析

    Institute of Scientific and Technical Information of China (English)

    徐锦龙; 贾志海; 王伟; 罗雷; 李俊青


    The Jiangyou-Guangyuan area, which is located in the north margin of the Longmen Mountain Nappe Struc- tural Belts, is one of the classic areas for the upper Carboniferous researches in Sichuan Basin and even in the upper Yangtze Plate. The upper Carboniferous was deposited in semi-enclosed gulfs of the western Yangtze Block, which char- acterized by slight thickness, light color, many fossils and several fuchsia mudstone and containing gravels bioclastic limestone as a set of semi-restricted platform and open platform carbonate rocks in this area. The strata are revised ac- cording to sedimentary types, sedimentary structures, lithological characters, and paleontological combinations. The up- per Zongchanggou Formation, which was considered as one part of the lower Carboniferous, is amended to the upper Carboniferous Huanglong Formation in this paper. The upper Carboniferous is divided into four parts, as lower Huan- glong Formation, middle Huanglong Formation, upper Huanglong Formation and lower Chuanshan Formation. Fifteen microfacies can be divided according to field observation, laboratory micro-analysis and classification of car- bonate rocks by Dunham, as Unfossiliferous mudstones (MFI-1), Clastizoic mudstones (MF1-2), Calcareous green al- gae wackestones ( MF2-1 ), Bioclastic wackestones ( I~IF2-2), Birdseyes-Fenestral pelletoid packstones ( MF3 ), Bivalve wackestones (MF4-1), Bivalve packstones (MF4-2), Calcareous green algae packstones (MF5-1), Fusulinid pack- stones (MF5-2), Bioclastic wackestones with oncoids (MF5-3), Bioclastic wackestones (MF5-4), Fine- grained pe- loid grainstones (MF6), Bioclastic grainstones (MF7-1), Fusulinid grainstones (MF7-2), Worn foraminiferal grain- stones (MF7-3), Coated bioclastic grainstones (MF8), Bahamite peloids grainstones (MF9-1), Bioclastic-Bahamite peloids grainstones (MF9-2), Ooid grainstones with radial ooids( MF10-1 ), Ooid grainstones with micritizatal concen- tric ooids ( MF10-2), Lithoclasts grainstones with

  3. Change of the glaciation dimensions in the basins of Malaya Laba and Belaya Rivers (West Caucasus for the last hundred years

    Directory of Open Access Journals (Sweden)

    Yu. V. Efremov


    Full Text Available Changes in area of glaciation and quantity of individual glaciers in basins of rivers Malaya Laba and Belaya (West Caucasus are investigated. The Glacier Inventories of 1911 [19] and 1967 [10] and space imagery for 2000–2012 are used as the base materials. Sizes of some glacier were corrected in field studies by GPS positioning and ground theodolite surveys. It was determined that, like in many other glacier basins of the Great Caucasus, the glaciations in this region decreased. For the period of 1902/1906–2013 the glaciations area reduced by 12.0 km2 (or by 43.8%. For the same period the glacier quantity decreased by eight (11.8%, and in 2013 sixty glaciers remained. According to calculations, mean annual rate of the glacier retreat amount to about 2 m. Small glaciers and snow patches remain in places of melted glaciers which keep some properties of glaciers (so called firn glaciers.

  4. The Location and Styles of Ice-Free “Oases” during Neoproterozoic Glaciations with Evolutionary Implications

    Directory of Open Access Journals (Sweden)

    Daniel Paul Le Heron


    Full Text Available Evidence based on molecular clocks, together with molecular evidence/biomarkers and putative body fossils, points to major evolutionary events prior to and during the intense Cryogenian and Ediacaran glaciations. The glaciations themselves were of global extent. Sedimentological evidence, including hummocky cross-stratification (representing ice-free seas affected by intra-glacial storms, dropstone textures, microbial mat-bearing ironstones, ladderback ripples, and wave ripples, militates against a “hard” Snowball Earth event. Each piece of sedimentological evidence potentially allows insight into the shape and location, with respect to the shoreline, of ice-free areas (“oases” that may be viewed as potential refugia. The location of such oases must be seen in the context of global paleogeography, and it is emphasized that continental reconstructions at 600 Ma (about 35 millions years after the “Marinoan” ice age are non-unique solutions. Specifically, whether continents such as greater India, Australia/East Antarctica, Kalahari, South and North China, and Siberia, were welded to a southern supercontinent or not, has implications for island speciation, faunal exchange, and the development of endemism.

  5. 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


    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.

  6. Late Carboniferous to early Permian sedimentaryetectonic evolution of the north of Alxa, Inner Mongolia, China:Evidence from the Amushan Formation

    Institute of Scientific and Technical Information of China (English)

    Haiquan Yin; Hongrui Zhou; Weijie Zhang; Xiaoming Zheng; Shengyu Wang


    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 back-ground, 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 Carboniferouseearly Permian. The charac-teristics of the regional tectonic evolution of the area indicate that the region may form a small part of the GobieTianshan rift of southern Mongolia.

  7. [Mountain medicine - an introduction. I]. (United States)

    Hjuler, Kasper Fjellhaugen; Bay, Bjørn


    Tourism to high-altitude areas is increasingly popular even from low-lying regions such as Denmark. Mountain sports include skiing, mountaineering, and ski touring. The young, elderly and at-risk individuals with pre-existing illnesses engage in recreational mountain activities. Thus, risk assessment and counselling regarding altitude exposure is increasingly relevant to all healthcare providers. In this first article of two in a review series, we summarize the state of the art of altitude physiology, alpine dangers and avalanches, and medical aspects of the increased UV-exposure at altitude.

  8. 27 CFR 9.80 - York Mountain. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false York Mountain. 9.80... Mountain. (a) Name. The name of the viticultural area described in this section is “York Mountain.” (b) Approved map. The approved map for the York Mountain viticultural area is the U.S.G.S. map entitled...

  9. 27 CFR 9.108 - Ozark Mountain. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ozark Mountain. 9.108... Ozark Mountain. (a) Name. The name of the viticultural area described in this section is “Ozark Mountain.” (b) Approved maps. The appropriate maps for determining the boundaries of Ozark Mountain...

  10. 27 CFR 9.55 - Bell Mountain. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bell Mountain. 9.55... Mountain. (a) Name. The name of the viticultural area described in this section is “Bell Mountain.” (b) Approved map. The appropriate map for determining the boundaries of the Bell Mountain viticultural area...

  11. 27 CFR 9.167 - Red Mountain (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Red Mountain 9.167 Section... Mountain (a) Name. The name of the viticultural area described in this section is “Red Mountain.” (b) Approved maps. The appropriate map for determining the boundaries of the Red Mountain viticultural area...

  12. Rasnitsynala sigambrorum gen. et sp. n., a small odonatopterid (“Eomeganisoptera”, “Erasipteridae” from the early Late Carboniferous of Hagen-Vorhalle (Germany

    Directory of Open Access Journals (Sweden)

    Wolfgang Zessin


    Full Text Available Besides Erasipteroides valentini (Brauckmann in Brauckmann, Koch & Kemper, 1985, Zessinella siope Brauckmann, 1988, and Namurotypus sippeli Brauckmann & Zessin, 1989, Rasnitsynala sigambrorum gen. et sp. n. is the fourth species of the Odonatoptera from the early Late Carboniferous (Early Pennsylvanian: Namurian B, Marsdenian deposits of the important Hagen-Vorhalle Konservat-Lagerstätte in Germany. With its wing-span of about 55mm it is unusually small even for the “Eomeganisoptera”. Its venation resembles other small “Eomeganisoptera”, in particular Z. siope. This is why it is here assigned to the probably paraphyletic “Erasipteridae” Carpenter, 1939.

  13. Rasnitsynala sigambrorum gen. et sp. n., a small odonatopterid ("Eomeganisoptera", "Erasipteridae") from the early Late Carboniferous of Hagen-Vorhalle (Germany). (United States)

    Zessin, Wolfgang; Brauckmann, Carsten; Gröning, Elke


    Besides Erasipteroides valentini (Brauckmann in Brauckmann, Koch & Kemper, 1985), Zessinella siope Brauckmann, 1988, and Namurotypus sippeli Brauckmann & Zessin, 1989, Rasnitsynala sigambrorumgen. et sp. n. is the fourth species of the Odonatoptera from the early Late Carboniferous (Early Pennsylvanian: Namurian B, Marsdenian) deposits of the important Hagen-Vorhalle Konservat-Lagerstätte in Germany. With its wing-span of about 55 mm it is unusually small even for the "Eomeganisoptera". Its venation resembles other small "Eomeganisoptera", in particular Zessinella siope. This is why it is here assigned to the probably paraphyletic "Erasipteridae" Carpenter, 1939.

  14. Erosion-driven uplift in the Gamburtsev Subglacial Mountains of East Antarctica (United States)

    Paxman, G. J. G.; Watts, A. B.; Ferraccioli, F.; Jordan, T. A.; Bell, R. E.; Jamieson, S. S. R.; Finn, C. A.


    The relative roles of climate and tectonics in mountain building have been widely debated. Central to this debate is the process of flexural uplift in response to valley incision. Here we quantify this process in the Gamburtsev Subglacial Mountains, a paradoxical tectonic feature in cratonic East Antarctica. Previous studies indicate that rifting and strike-slip tectonics may have provided a key trigger for the initial uplift of the Gamburtsevs, but the contribution of more recent valley incision remains to be quantified. Inverse spectral (free-air admittance and Bouguer coherence) methods indicate that, unusually for continents, the coherence between free-air gravity anomalies and bedrock topography is high (>0.5) and that the elastic thickness of the lithosphere is anomalously low (erosion are quantified: dendritic fluvial incision overprinted by Alpine-style glacial erosion in the Gamburtsevs and outlet glacier-type selective linear erosion in the Lambert Rift, part of the East Antarctic Rift System. 3D flexural models indicate that valley incision has contributed ca. 500 m of peak uplift in the Gamburtsevs and up to 1.2 km in the Lambert Rift, which is consistent with the present-day elevation of Oligocene-Miocene glaciomarine sediments. Overall, we find that 17-25% of Gamburtsev peak uplift can be explained by erosional unloading. These relatively low values are typical of temperate mountain ranges, suggesting that most of the valley incision in the Gamburtsevs occurred prior to widespread glaciation at 34 Ma. The pre-incision topography of the Gamburtsevs lies at 2-2.5 km above sea-level, confirming that they were a key inception point for the development of the East Antarctic Ice Sheet. Tectonic and/or dynamic processes were therefore responsible for ca. 80% of the elevation of the modern Gamburtsev Subglacial Mountains.

  15. The Dilemma of Mountain Roads (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.

  16. A mountain of millipedes IV

    DEFF Research Database (Denmark)

    Enghoff, Henrik


    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...

  17. The Table Mountain Field Site (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...

  18. 对西天山石炭纪地层及生物群的一些认识%Some Understandings about Carboniferous Strata and Biota of Western Tianshan,Xinjiang

    Institute of Scientific and Technical Information of China (English)



    据前人资料结合1∶25万区调新资料研究成果,对西天山石炭纪典型岩石地层单位及时代、基本特征形成一些新的认识.对新疆北部石炭系腕足“管孔石燕动物群”、“安加拉植物群”及腕足“拟穆武贝动物群”的分布范围、生物区系意义进行总结和讨论.利用多年来西天山陆续发现的菊石化石,建立了本区7个石炭纪菊石带,并结合“R带”为主的菊石化石资料对西天山上、下石炭统年代界线进行讨论.%Based on the regional geological data that completed so many years especially new materials of recent years,this article mainly deal with the carboniferous lithostratigraphic units,biota and ammonoids zone of western Tianshan.Three typical carboniferous biota of "northern type",early carboniferous "Syringothyris fauna",late carboniferous "Angara flora", late carboniferous"Paramuirwoodia fauna",and theirs distribution are discussed in this peper.Acoding to some important ammonoids have been discovered last decades,sevem ammonoids zone can be recognized,they are Dzhaprakocera (Akesahkeceras)Zone,Beyrichoceras-Goniatites Zone,Platygoniatites zone,Homoceras Zone,Reticuloceras Zone,Diaboloceras Zone and Paralegoceras Zone.The lower and upper carboniferous boundary should be drawn at the middle of Homoceras and Reticuloceras zone.

  19. 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

    Energy Technology Data Exchange (ETDEWEB)

    Kotarba, M.J.; Pluta, I. [AGH University of Science & Technology, Krakow (Poland)


    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{sub 4}, small amounts of higher gaseous hydrocarbons, and CO{sub 2}) and microbial (CH{sub 4}, very small amounts of ethane, and CO{sub 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.


    Institute of Scientific and Technical Information of China (English)


    Tsering Dorje:I Dream of Climbing Mt. Qomolangma Carrying the Olympic Torch Tsering Dorje,the oldest of the Tibetan professional mountaineers,has successfully reached a total of fourteen of the world's highest mountain summits.His companions jokingly refer to him as"Aku"(meaning"uncle"in Tibetan).However, acting as an uncle,he has to shoulder the responsibilities of team leader to take care of the others.

  1. Mountain Child: Systematic Literature Review. (United States)

    Audsley, Annie; Wallace, Rebecca M M; Price, Martin F


    Objectives This systematic review identifies and reviews both peer-reviewed and 'grey' literature, across a range of disciplines and from diverse sources, relating to the condition of children living in mountain communities in low- and middle-income countries. Findings The literature on poverty in these communities does not generally focus on the particular vulnerabilities of children or the impact of intersecting vulnerabilities on the most marginalised members of communities. However, this literature does contribute analyses of the broader context and variety of factors impacting on human development in mountainous areas. The literature on other areas of children's lives-health, nutrition, child mortality, education, and child labour-focuses more specifically on children's particular vulnerabilities or experiences. However, it sometimes lacks the broader analysis of the many interrelated characteristics of a mountainous environment which impact on children's situations. Themes Nevertheless, certain themes recur across many disciplines and types of literature, and point to some general conclusions: mountain poverty is influenced by the very local specificities of the physical environment; mountain communities are often politically and economically marginalised, particularly for the most vulnerable within these communities, including children; and mountain communities themselves are an important locus for challenging and interrupting cycles of increasing inequality and disadvantage. While this broad-scale review represents a modest first step, its findings provide the basis for further investigation.

  2. Assessing hydrologic components of a glaciated catchment in the central Himalaya (United States)

    Paramithiotti, Vittoria; Bookhagen, Bodo; Soncini, Andrea; Confortola, Gabriele; Vuillermoz, Elisa; Diolaiuti, Guglielmina; Bocchiola, Daniele


    The Hindu-Kush Karakoram and Himalaya (HKKH) mountains are the water towers of Asia, as they deliver water to nearly half of the world's population. Despite so, it is mostly unclear what is the relative contribution of rainfall, snow and ice-melt to hydrological fluxes in this area. Here, we study the Dudh Kosi River catchment (450 to 8848 m asl, ca. 4000 km2) in central Nepal, including the Khumbu glacier at Mt. Everest's toe. Two critical components for predicting hydrologic fluxes in steep mountain ranges are: (1) accurate information of energy and mass fluxes, especially at high altitudes, and (2) depiction of rainfall and snowfall amount and dynamics. In this study, we use a combination of unique ground-control data and remote-sensing data to provide realistic hydrologic modeling boundary conditions. We primarily relied on and validated (1) Moderate Resolution Imaging Spectroradiometer (MODIS) product MOD11/MYD11, to calculate day/night land surface temperatures and monthly lapse rates; (2) Tropical Rainfall Measurement Mission (TRMM) 3-hourly rainfall data from TRMM product 3B42 with 0.25° x 0.25° spatial resolution; and (3) MODIS product MOD10/MYD10 to derive daily snow covered areas. Ground-control data are derived from high altitude stations provided by the Ev-K2-CNR Committee of Italy, as well as from data of the Department of Hydrology and Meteorology (DHM) at lower elevations. We model hydrological run-off processes with a semi-distributed, altitude-belt based model. While the validated remote-sensing data generally provide good agreement with station data, snowfall component is not well depicted. We rely upon a correlation of precipitation with altitude combined with snow depth measurements at the EV-K2-CNR Pyramid (5050 m asl) to evaluate snowfall contribution. We use a degree-day approach and explicitly treat debris coverage on ice and snow. Our preliminary results indicate that approximately 20% of annual discharge is derived from snow and ice

  3. Permo-Carboniferous coal measures in the Qinshui basin: Lithofacies paleogeography and its control on coal accumulation

    Institute of Scientific and Technical Information of China (English)

    SHAO Longyi; XIAO Zhenghui; LU Jing; HE Zhiping; WANG Hao; ZHANG Pengfei


    The Qinshui basin in southeastern Shanxi Province is an important base for coalbed methane explora-tion and production in China. The methane reservoirs in this basin are the Carboniferous and Permian coals. Their thick-ness is strongly controlled by the depositional environments and the paleogeography. In this paper, sedimentological research was undertaken on the outcrop and borehole sections of the Taiyuan and Shanxi formations in the Qinshui basin and the basin-wide lithofacies paleogeography maps for these two formations have been reconstructed. The Taiyuan Forma-tion is composed of limestones, alttrninous mudstones, silt-stones, silty mudstones, sandstones, and mineable coal seams,with a total thickness varying from 44.9 m to 193.48 m. The coal seams have a thickness ranging between 0.10 and 16.89 m, averaging 7.19 m. During the deposition of the Taiyuan Formation, the northern part of the basin was domi-nated by a lower deltaic depositional system, the central and southern parts were dominated by a lagoon environment, and the southeastern comer was occupied by a carbonate platform setting. Coal is relatively thick in the northern part and the southeastern corner. The Shanxi Formation consists of sand-stones, siltstones, mudstones, and coals, with the limestones being locally developed. The thickness of the Shanxi Forma-tion is from 18.6 m to 213.25 m, with the thickness of coal seams from 0.10 to 10 m and averaging 4.2 m. During the deposition of the Shanxi Formation, the northern part of the Qinshui basin was mainly dominated by a lower deltaic plain distributary channel environment, the central and southern parts were mainly an interdistributary bay environment, and the southeastern part was occupied by a delta front mouth bar environment. The thick coals are distributed in the central and southern parts where an interdistributary bay dominates. It is evident that the thick coal zones of the Taiyuan Formation are consistent with the sandstone-rich belts

  4. Primary and redeposited facies from a large-magnitude, rhyolitic, phreatomagmatic eruption: Cana Creek Tuff, Late Carboniferous, Australia (United States)

    McPhie, J.


    The Cana Creek Tuff is one of four rhyolitic ignimbrite members of the Late Carboniferous Currabubula Formation, a volcanogenic conglomeratic braidplain sequence exposed along the western margin of the New England Orogen in northeastern New South Wales. The source is not exposed but was probably located tens of kilometres to the west of existing outcrops. The medial to distal parts of the tuff average about 70 m in thickness, are widespread (minimum present area ˜ 1400 km 2), and comprise a primary pyroclastic facies (ignimbrite, ash-fall tuff) and a redeposited volcaniclastic facies (sandstone, conglomerate). Both facies are composed of differing proportions of crystal fragments (quartz, plagioclase, K-feldspar), pumiceous clasts (pumice, shards, fine ash), and accidental lithics. The eruption responsible for this unit was explosive and of large magnitude (dense rock equivalent volume about 100 km 3). That it was also phreatomagmatic in character is proposed on the basis of: the intimate association of primary and redeposited facies; the presence of accretionary lapilli both in ignimbrite and in ash-fall tuff; the fine grain size of juvenile pyroclasts; the low grade of the ignimbrite; and the close similarity in facies, composition and magnitude to the deposits from the 20,000y. B.P. phreatomagmatic eruption at Taupo, New Zealand (the Wairakei and parts of the Hinuera Formations). The eruption began and ended from a vent with excess water available, possibly submersed in a caldera lake, and generated volcaniclastic sheet floods and debris flows. The emplacement of the primary pyroclastic facies is correlated with an intervening stage when the water:magma mass ratio was lower. The deposits from a large-magnitude, phreatomagmatic eruption are predicted to show systematic lateral variations in facies. Primary pyroclastic facies predominate near the source although the preserved stratigraphy is an incomplete record because of widespread contemporaneous erosion

  5. 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


    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

  6. The origins of mountain geoecology

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    Ives, Jack D.


    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

  7. 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)


    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.

  8. Little Ice Age Glaciation in Alaska: A record of recent global climatic change

    Energy Technology Data Exchange (ETDEWEB)

    Calkin, P.E.; Wiles, G.C.


    General global cooling and temperature fluctuation accompanied by expansion of mountain glaciers characterized the Little Ice Age of about A.D. 1200 through A.D. 1900. The effects of such temperature changes appear first and are strongest at high latitudes. Therefore the Little Ice Age record of glacial fluctuation in Alaska may provide a good proxy for these events and a test for models of future climatic change. Holocene expansions began here as early as 7000 B.P. and locally show a periodicity of 350 years after about 4500 years B.P. The Little Ice Age followed a late Holocene interval of minor ice advance and a subsequent period of ice margin recession lasting one to seven centuries. The timing of expansions since about A.D. 1200 have often varied between glaciers, but these are the most pervasive glacial events of the Holocene in Alaska and frequently represent ice marginal maxima for this interval. At least two major expansions are, apparent in forefields of both land-terminating and fjord-calving glaciers, but the former display the most reliable and detailed climatic record. Major maxima occurred by the 16th century and into the mid-18th century. Culmination of advances occurred throughout Alaska during the 19th century followed within a few decades by general glacial retreat. Concurrently, equilibrium line altitudes have been raised 100-400 m, representing a rise of 2-3 deg C in mean summer temperature.

  9. The impact of solar radiation and solar activity on climate variability after the end of the last glaciation (United States)

    Dergachev, V. A.


    This paper analyzes climate changes since the end of the last glaciations 19-20 thousand years ago, including the modern warm interglacial Holocene age, which started about 11.5 thousand years ago. The connection between the impact of the orbital effect and solar activity on the Earth's climate is studied. This is important for estimation of the duration of the modern interglacial period. It is shown that there is significant inconsistency between temperature variations in Holocene, which is deduced from the large amount of recently obtained indirect data and the temperatures reproduced in the climate models. The trends of climate cooling in the Holocene on the whole and during the last 2000 years are investigated.

  10. Genetic and morphological consequences of Quaternary glaciations: A relic barbel lineage (Luciobarbus pallaryi, Cyprinidae) of Guir Basin (Algeria). (United States)

    Brahimi, Amina; Tarai, Nacer; Benhassane, Abdelkrim; Henrard, Arnaud; Libois, Roland


    Climatic variations during the Quaternary period had a considerable impact on landscapes and habitat fragmentation (rivers) in North Africa. These historical events can have significant consequences on the genetic structure of the populations. Indeed, geographically separated and genetically isolated populations tend to differentiate themselves through time, eventually becoming distinct lineages, allowing new species to emerge in later generations. The aim of the present study is to use genetic and morphological techniques to evaluate the major role of the Saalian glaciation (Middle Quaternary) in the establishment of the geographic space and in the evolution of the intraspecific genetic diversity, by tracing the demographic history of barbels belonging to the Luciobarbus pallaryi (Cyprinidae) species in the Guir Basin (Algeria). In this context, two populations, from two distinct and isolated sites, were studied. Analysis of the cytochrome b (cyt b) mitochondrial markers and of the "D-loop" control region has shown that the "upstream" and "downstream" Guir populations are genetically differentiated. The molecular analyses suggest that the upstream population was disconnected from this hydrographic system during the Saalian glaciation period of the Quaternary. Subsequently, it was isolated in the foggaras underground waters in the Great Western Erg, at approximately 320 000 years BP, creating, through a bottleneck effect, a new allopatric lineage referred to as "Adrar". Conversely, the high genetic diversity in the upstream Guir (Bechar) population suggests that the stock is globally in expansion. These barbels (n=52) were also examined with meristic, morphometric, osteological, and biological features. These data also reveal a complete discrimination between the two populations, with a remarkable and distinctive behavioural adaptation for the Adrar specimens: neoteny.

  11. Ocean barriers and glaciation: evidence for explosive radiation of mitochondrial lineages in the Antarctic sea slug Doris kerguelenensis (Mollusca, Nudibranchia). (United States)

    Wilson, Nerida G; Schrödl, M; Halanych, Kenneth M


    Strong currents and deep passages of water can be barriers for larval dispersal of continental marine animals, but potential effects on direct developers are under-investigated. We examined the genetic structure of Doris kerguelenensis, a directly developing sea slug that occurs across the Drake Passage, the body of water separating Antarctica from South America. We found deep mitochondrial divergences within populations on both sides of the Drake Passage, and South American animals formed multiple sister-group relationships with Antarctic animals. A generalised molecular clock suggested these trans-Drake pairs diverged during the Pliocene–Pleistocene, after the formation of the Drake Passage. Statistical parsimony methods recovered 29 separate haplotype networks (many sympatric) that likely correlate with allopatric events caused by repeated glacial cycles. Data from 16S were congruent but more conserved than COI, and the estimated ancestral 16S haplotype was widespread. The marked difference in the substitution rates between these two mitochondrial genes results in different estimates of connectivity. Demographic analyses on networks revealed some evidence for selection and expanding populations. Contrasting with the Northern Hemisphere, glaciation in Antarctica appears to have increased rather than reduced genetic diversity. This suggests orbitally forced range dynamics based on Northern Hemisphere phylogeography do not hold for Antarctica. The diverse lineages found in D. kerguelenensis point towards a recent, explosive radiation, likely reflecting multiple refuges during glaciation events, combined with limited subsequent dispersal. Whether recognised as cryptic species or not, genetic diversity in Antarctic marine invertebrates appears higher than expected from morphological analyses, and supports the Antarctic biodiversity pump phenomenon.

  12. Defining near-surface groundwater flow regimes in the semi-arid glaciated plains of North America. (United States)

    Hendry, M Jim; Barbour, S Lee; Schmeling, Erin E


    The dominant transport mechanisms controlling the migration of contaminants in geologic media are advection and molecular diffusion. To date, defining which transport mechanism dominates in saturated, non-lithified sediments has been difficult. Here, we illustrate the value of using detailed profiles of the conservative stable isotope values of water (δ(2)H and δ(18)O) to identify the dominant processes of contaminant transport (i.e. diffusion- or advection-dominated transport) in near-surface, non-lithified, saturated sediments of the Interior Plains of North America (IPNA). The approach presented uses detailed δ(18)O analyses of glacial till, glaciolacustrine clay, and fluvial sand core samples taken to depths of 11-50 m below ground at 22 sites across the IPNA to show whether transport in the fractured and oxidized sediments is dominated by advection or diffusion. Diffusion is by far the dominant transport mechanism in fine-textured lacustrine and glacial till sediments, but lateral advection dominates transport in sand-rich sediments and some oxidized, fine-textured lacustrine and glacial till sediments. The approach presented has a number of applications, including identifying dominant transport mechanisms in geomedia and potential protective barriers for underlying aquifers or surface waters, constraining groundwater transport models, and selecting optimum locations for monitoring wells. These findings should be applicable to most glaciated regions of the world that are composed of similar hydrogeologic units (i.e. low K clay till layers overlain by higher K coarse-textured aquifers or weathered clay till layers) and may also be applicable to non-glaciated regions exhibiting similar hydrogeologic characteristics.

  13. Mineralogy of Rock Flour in Glaciated Volcanic Terrains: An Analog for a Cold and Icy Early Mars (United States)

    Rampe, E. B.; Horgan, B.; Scudder, N.; Smith, R. J.; Rutledge, A. M.


    Geomorphological and mineralogical data from early Martian surfaces indicate liquid water was present on ancient Mars. The relative surface temperatures, however, remain a subject of debate. Was early Mars warm and wet or cold and icy with punctuated periods of warmth and ice melt? By characterizing the mineralogy and geochemistry of modern icy mafic terrains on Earth, we can search for these characteristics in early Martian terrains to better constrain the early Martian climate. Here, we describe the mineralogy of glacial flour in a modern glaciated volcanic terrain in Oregon, USA. We are particularly interested in secondary phases that form in these environments, and we hypothesize that poorly crystalline phases may preferentially form in these terrains because of the low temperatures and the seasonality of melt water production. A description of the mineralogy of the moraines, the composition of the amorphous materials, and the geochemistry of the glacial melt waters are presented elsewhere. Glacial flour is made up of silt- and clay-sized particles that form from the physical weathering of rock underlying a wet-based glacier as the glacier slides over it. Flour is usually transported from underneath a glacier by melt water streams. The geochemistry of glacial melt water streams has been studied extensively and has been used to infer weathering reactions within glacial systems. However, the mineralogy of these environments, especially on mafic volcanic terrains, is not well studied. Rock flour is a ubiquitous physical weathering product in glaciated terrains and, therefore, affects microbial habitats, stream and lake chemistry, and chemical weathering processes. and by studying the mineralogy of glacial flour, we can better understand geochemical and microbiological processes in subglacial and proglacial terrains.

  14. Early Holocene High Magnitude Debris Flow Events and Environmental Change as Illustrated by the Moxi Platform, Hengduan Mountains, SW China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junyan; CHENG Genwei; LI Yongfei


    Thick debris flow deposits in the Hengduan Mountains of southwestern China record landscape instability at the close of the last glaciation and in the early Holocene. The deposits, ranging in thickness from 100 to 200 m, are common and in high magnitude in the valleys of this region. They are products of large debris flows induced by glacier and enabled by the presence of large amount of glacial debris on the landscape. The carbon 14 dating from Moxi Platform indicates that a period of catastrophic debris flows occurred at c. 7 kyr B.P., and was concurrent with other glacial-fluvial fans and terraces which tied to regional climatic oscillations elsewhere in the Himalaya. The comparable events suggest a strong climatic control on earth surface processes for the dynamics, magnitude, and frequency in this region.

  15. Water yield and sediment export in small, partially glaciated Alpine watersheds in a warming climate (United States)

    Micheletti, Natan; Lane, Stuart N.


    Climate change is expected to modify the hydrological and geomorphological dynamics of mountain watersheds significantly, so impacting on downstream water yield and sediment supply. However, such watersheds are often poorly instrumented, making it difficult to link recent and rapid climate change to landscape response. Here we combine unique records of river flow and sediment export, with historical archival imagery to test the hypothesis that climate warming has substantially increased both water yield and sediment export from small Alpine watersheds (<3 km2) characterized by small (<0.5 km2 surface) glaciers. To examine ice and landform response to climate change, we apply archival digital photogrammetry to historical aerial imagery available from 1967 to present. We use the resulting data on ice loss, in combination with reliable records of stream flow from hydroelectric power intakes and climate data to approximate a water budget and to determine the evolution of different contributions to river flow. We use the stream flow records to estimate volumetric sediment transport capacity and compare this with the volumes of sand and gravel exported from the watersheds, quantified from records of intake flushing. The data show clearly that climate forcing since the early 1980s has been accompanied by a net increase in both water yield and sediment transport capacity, and we attribute these as signals of reduced snow accumulation and glacier recession. However, sediment export has not responded in the same way and we attribute this to limits on sediment delivery to streams because of poor rockwall-hillslope-channel connectivity. However, we do find that extreme climate conditions can be seen in sediment export data suggesting that these, rather than mean climate warming, may dominate watershed response.

  16. Late Quaternary glaciation of the Upper Soca River Region (Southern Julian Alps, NW Slovenia) (United States)

    Bavec, Milos; Tulaczyk, Slawek M.; Mahan, Shannon; Stock, Gregory M.


    Extent of Late Quaternary glaciers in the Upper Soc??a River Region (Southern Julian Alps, SE Europe) has been analyzed using a combination of geological mapping, glaciological modeling, and sediment dating (radiocarbon, U/Th series and Infrared Stimulated Luminescence-IRSL). Field investigations focused mainly on relatively well preserved Quaternary sequences in the Bovec Basin, an intramontane basin located SW of the Mediterranean/Black Sea divide and surrounded by mountain peaks reaching from approximately 2100 up to 2587 m a.s.l. Within the Basin we recognized two Late Quaternary sedimentary assemblages, which consist of the same facies association of diamictons, laminated lacustrine deposits and sorted fluvial sediments. Radiocarbon dating of the upper part of the lake sediments sequence (between 12790??85 and 5885??60 14C years b.p.) indicates that the younger sedimentary assemblage was deposited during the last glacial maximum and through early Holocene (Marine Isotope Stage 21, MIS 2-1). Sediment ages obtained for the older assemblage with U/Th and IRSL techniques (between 154.74??22.88 and 129.93??7.90 ka b.p. for selected samples) have large errors but both methods yield results consistent with deposition during the penultimate glacial-interglacial transition (MIS 6-5). Based on analyses of field data combined with glaciological modeling, we argue that both sediment complexes formed due to high sediment productivity spurred by paraglacial conditions with glaciers present in the uplands around the Bovec Basin but not extending down to the basin floor. Our study shows that the extent and intensity of direct glacial sedimentation by Late Quaternary glaciers in the region was previously significantly overestimated. ?? 2004 Elsevier B.V. All rights reserved.

  17. A geochemical modelling study of the evolution of the chemical composition of seawater linked to a global glaciation: implications for life sustainability

    Directory of Open Access Journals (Sweden)

    G. Le Hir


    Full Text Available The Snowball Earth theory initially proposed by Kirschvink (Kirschvink, 1992 to explain the Neoproterozoic glacial episodes, suggested that the Earth was fully ice-covered at 720 My (Sturtian episode and 640 My (Marinoan episode. This succession of extreme climatic crises induced a stress which is considered as a strong selective pressure on the evolution of life (Hoffman et al., 1998. However recent biological records (Corsetti, 2006 do not support this theory as little change is observed in the diversity of microfossils outcrops before and after the Marinoan glacial interval. In this contribution we address this apparent paradox. Using a numerical model of carbon-alkalinity global cycles, we quantify several environmental stresses caused by a global glaciation. We suggest that during global glaciations, the ocean becomes acidic (pH~6, and unsaturated 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 show that the buffering action of the oceanic crust dissolution processes avoids a total collapse of biological productivity. In opposite short-lived and large post-glacial perturbations are more critical and may have played a role of environmental filter suggested in the classic snowball Earth theory. Only a permissive life (prokaryotes or simple eukaryotes may explain the relative continuity in microfossils diversity observed before, during and

  18. Influence of ENSO and PDO on mountain glaciers in the outer tropics: case studies in Bolivia (United States)

    Veettil, Bijeesh Kozhikkodan; Bremer, Ulisses Franz; de Souza, Sergio Florêncio; Maier, Éder Leandro Bayer; Simões, Jefferson Cardia


    This paper emphasize on the observational investigation of an ice-covered volcano and two glaciated mountains in the Central Andes from 1984 to 2011. Annual snowlines of the Nevado Sajama in the Cordillera Occidental and the Nevado Cololo and the Nevado Huanacuni in the Cordillera Apolobamba in Bolivia were calculated using remote sensing data. Landsat TM, Landsat ETM+, and LISS-III images taken during the end of dry season were used in this study. Changes in the highest annual snowline during May-September is used an indirect measure of the changes in the equilibrium line altitude of the glaciers in the outer tropics. We tried to understand the combined influence of the El Niño-Southern Oscillation and the Pacific Decadal Oscillation on the variations in the annual snowline altitude of the selected glaciers. Meteorological data in the form of gridded datasets were used for calculating the anomalies in precipitation and temperature during the study period. It is found that the glaciated areas were fluctuated with the occurrence of warm and cold phase of ENSO but the magnitude of the influence of ENSO is observed to be controlled by the phase changes of PDO. Snowline of the Nevado Sajama fluctuated heavily when cold and warm phases of ENSO occur during the cold and warm regimes of PDO, respectively. Nevado Cololo and Nevado Huanacuni are showing a continuous retreating trend during the same period. This clearly indicates that the changes in the Pacific SST patterns have more influence on glaciers in the Cordillera Occidental compared with those in the Cordillera Oriental of the Bolivian Andes.

  19. Mid-Carboniferous conglomerates in southwestern Europe record early Variscan intracontinental convergence: evidence that channels were exhumed before thermal weakening of the lithosphere (United States)

    Martinez, Francisco J.; Dietsch, Craig; Aleinikoff, John; Cirès, Jordi


    The early part of the intracontinental geodynamic evolution of the Variscan chain in southwestern Europe is recorded by polymict conglomerates found in flysch basins paired with exhumed crystalline massifs. The conglomerates contain pebbles and cobbles of deformed granite and mid- to lower-crustal metamorphic rock, and in southern France and northeastern Spain have been assigned a Visean-Namurian age based on biostratigraphy. In the Catalan Coastal Ranges, where Alpine deformation and metamorphism are absent, conglomerates are deformed, cross-cut by granite, and contact metamorphosed to andalusite-cordierite grade. Foliation in the pebbles and cobbles is not coplanar with foliation in their pelitic matrix: the conglomerates record exhumation of crust that was already deformed, metamorphosed, and exhumed before the Visean. In the Guilleries massif of NE Spain, gneisses were exhumed ≈10 km before 324 Ma. Conglomerate samples from eight flysch basins, from north to south: Montagne Noire, Mouthoumet massif, SE Pyrenees, and five localities in the Catalan Coastal Ranges, were collected for detrital zircon age determinations using the USGS/Stanford SHRIMP-RG. The flysch basins have principal sources of pre-Cadomian, Cadomian, Cambro-Ordovician, Devonian, and Carboniferous ages. The dominance of Paleozoic ages indicates local orthogneiss and Variscan granite as primary sources, implying intra-Carboniferous exhumation rates as high as 5-10 mm/a. The maximum depositional age of each flysch conglomerate may show a trend of younging to the south [330 Ma (Montagne Noire) - 340 Ma (Mouthoumet) - 324 Ma (Poblet) -328 (Perinet)], suggesting deposition in front of advancing thrust nappes. In the Pineda basin, a dike of undeformed granite which cross-cuts conglomerate is 304 ± 2 Ma (SHRIMP U-Pb zircon data), providing a minimum age constraint on the time of deposition. In the Montagne Noire and the Mouthoumet massif, flysch basins are deformed by structures related to nappe

  20. Early Carboniferous adakitic rocks in the area of the Tuwu deposit, eastern Tianshan, NW China: Slab melting and implications for porphyry copper mineralization (United States)

    Wang, Yin-Hong; Xue, Chun-Ji; Liu, Jia-Jun; Wang, Jian-Ping; Yang, Jun-Tao; Zhang, Fang-Fang; Zhao, Ze-Nan; Zhao, Yun-Jiang; Liu, Bin


    Existing geochronological and geochemical data for the Early Carboniferous magmatic rocks in the eastern Tianshan, Xinjiang, have been interpreted in a variety of theories regarding petrogenesis and geodynamic setting. The proposed settings include rift, back-arc basin, passive continental margin, island arc, ridge subduction, and post-collisional environment. To evaluate these possibilities, we present new SHRIMP zircon U-Pb geochronology and geochemical data, whole-rock geochemical, Hf isotope, and S isotope data for tonalitic rocks and ores associated with the Tuwu porphyry copper deposit located in the center of the late Paleozoic Dananhu-Tousuquan arc, eastern Tianshan. SHRIMP zircon U-Pb dating indicates that the magmatic activity and thus associated copper mineralization occurred ca.332 Ma. The tonalitic rocks are calc-alkaline granites with A/CNK values ranging from 1.16 to 1.58; are enriched in K, Rb, Sr, and Ba; and are markedly depleted in Nb, Ta, Ti, and Th. They show geochemical affinities similar to adakites, with high Sr, Al2O3, and Na2O contents and La/Yb ratios; low Y and Yb contents; and slight positive Eu anomalies. In situ Hf isotopic analyses of zircons yielded positive initial εHf(t) values ranging from 6.9 to 17.2. The δ34S values of the ore sulfides range from -3.0‰ to +1.7‰, reflecting a deep sulfur source. Our results indicate that the paleo-Tianshan oceanic slab was being simultaneously subducted northward beneath the Dananhu-Tousuquan arc, and southward beneath the Aqishan-Yamansu arc during the Early Carboniferous. The Tuwu adakitic tonalitic rocks were derived from the partial melting of the subducted paleo-Tianshan oceanic slab, which was subsequently hybridized by mantle wedge peridotites. The slab-derived magmas have considerably high copper contents and are highly oxidized, thus leading to porphyry copper mineralization. Such Early Carboniferous tonalitic rocks that are widespread in the eastern Tianshan define a province

  1. Evaluation of Carboniferous Source Rocks in Santanghu Basin%三塘湖盆地石炭系烃源岩评价

    Institute of Scientific and Technical Information of China (English)

    宋到福; 何登发; 王书荣; 李涤; 王志勇; 黄卫东


    三塘湖盆地石炭系烃源岩分布具有南厚北薄的特点,且以马朗凹陷和条湖凹陷的烃源岩厚度最大。烃源岩类型主要包括滨浅海相一海陆交互相的暗色泥岩、凝灰质泥岩和碳质泥岩。盆地内部石炭系烃源岩有机碳含量、生烃潜量及氯仿沥青A的含量均较丰富。干酪根稳定碳同位素值及岩石热解分析结果指示石炭系烃源岩有机质来源广泛,干酪根类型以Ⅱ型为主,也有少量Ⅰ型和Ⅲ型。大部分烃源岩样品实测镜质体反射率大于0.7%,对应的最大热解温度大于435℃,达到了有机质热演化的成熟至高成熟阶段。研究表明,三塘湖盆地石炭系烃源岩为一套好至极好的烃源岩,具有很高的生烃潜力。%The distribution of the Carboniferous source rocks in Santanghu basin is characterized by thick in south and thin in north, in which Malang and Tiaohu sags have the maximum thickness of them. The lithologic types of source rocks mainly include dark mudstone, tuffaceous mudstone and carbonaceous medstone deposited in littoral-neritic or marine-continental alternating environment. The total or- ganic carbon content, potential hydrocarbon generation amount and bitumen extraction abundance in them are all higher. RockEval pyroly- sis parameters suggest that the organic matter in Carboniferous source rocks is dominated by Type-Ⅱ kerogen, with minor Type-Ⅰ and -Ⅲ kerogen contribution. Vitrinite reflectance (Ro) values for most source rock samples are bigger than 0.7%, corresponding Tmax values is over 435℃, indicating a mature to high-mature stage for most source rocks. The study shows that all the Carboniferous source rocks in Santang- hu basin are high quality source rocks, with a good potential for hydrocarbon generation.

  2. Zircon U-Pb age, Hf isotope and geochemistry of Carboniferous intrusions from the Langshan area, Inner Mongolia: Petrogenesis and tectonic implications (United States)

    Liu, Min; Zhang, Da; Xiong, Guangqiang; Zhao, Hongtao; Di, Yongjun; Wang, Zhong; Zhou, Zhiguang


    Late Paleozoic was a critical period for the tectonic evolution of the northern margin of the Alxa-North China craton, but the evolutionary history is not well constrained. The Carboniferous intrusions in the Langshan area in the western part of the northern margin of the Alxa-North China craton are mainly composed of tonalite, quartz diorite, olivine gabbro and pyroxene peridotite. Zircon LA-ICP-MS U-Pb dating indicates that the Langshan Carboniferous intrusions were emplaced at ca. 338-324 Ma. The quartz diorites are characterized by high amounts of compatible trace elements (Cr, Ni and V) and high Mg# values, which may suggest a significant mantle source. The positive Pb and negative Nb-Ta-Ti anomalies, the variable εHf(t) (-6.9 to 2.0) values and the old Hf model ages (1218-1783 Ma) imply some involvement of ancient continental materials in its petrogenesis. The tonalite has relatively high Sr/Y ratios, low Mg#, Yb and Y contents, features of adakite-like rocks, negative εHf(t) values (-9.8 to -0.1) and older Hf model ages (1344-1953 Ma), which suggest significant involvement of ancient crust materials and mantle-derived basaltic component in its petrogenesis. The high Mg# values, high Cr and Ni contents, and low Zr and Hf contents of the mafic-ultramafic rocks show evidence of a mantle source, and the relatively low zircon εHf(t) values (-5.9 to 3.2) might point to an enriched mantle. The trace element characteristics indicate the influence of subducted sediments and slab-derived fluids. In the tectonic discrimination diagrams, all the rocks plot in subduction-related environment, such as volcanic arc and continental arc. Considering the regional geology, we suggest that the Carboniferous intrusions in the Langshan area were likely emplaced during the late stage of the southward subduction of the Paleo-Asian Ocean plate, which formed a continental arc along the northern margin of the Alxa-North China craton.

  3. Job performance in the mountain metros


    Mark C. Snead; Kate Watkins


    This issue of the Rocky Mountain Economist explores the labor market performance of the mountain state metropolitan areas, including recent industry trends and comparisons to state and national job performance.

  4. Rocky Mountain Spotted Fever: Statistics and Epidemiology (United States)

    ... The CDC Cancel Submit Search The CDC Rocky Mountain Spotted Fever (RMSF) Note: Javascript is disabled or ... please visit this page: About . Rocky Mountain Spotted Fever (RMSF) Symptoms, Diagnosis, and Treatment Statistics ...

  5. Cheyenne Mountain Air Force Station NPDES Permit (United States)

    Under NPDES permit CO-0034762, the Cheyenne Mountain Air Force Station is authorized to discharge from the interior storm drainage system and air exhaust stacks at the Cheyenne Mountain Complex, in El Paso County, Colorado, to tributaries Fountain Creek.

  6. Geomorphological map of glaciated gorges in a granitic massif (Gredos range, Central Spain). (United States)

    Campos, Néstor; Tanarro, Luis Miguel; Palacios, David


    A detailed geomorphological map on a 1:10,000 scale is presented for a high mountain area in Gredos range (Iberian Central System), this area is located in a granitic massif 160 km West of Madrid and comprises three gorges : La Vega, Taheña-Honda and La Nava. Only few detailed geomorphological maps of the Gredos range are available despite the wide diversity of landforms, in order to improve the understanding of this zone, this geomorphological map of the area has been produced, showing in detail the geomorphologic diversity of these gorges. The map was created with the aid of 25 cm resolution aerial photographs, 25 cm resolution satellite images, Iberpix 3D images provided by the Spanish National Geographic Institute and verified with field work. The landforms were delimitated with a stereoscope and satellite image pairs and digitized using GIS and CAD software, in some areas 3D glasses has been used with 3D images and the software Esri ArcScene. The landforms resulting from interpretation of aerial photographs and satellite images were classified using the IGUL (Institute of Geography, University of Lausanne) legend system (developed at the end of the 1980s) combined with the legend proposed by Peña et al. (1997) and some personal adaptations. The map legend includes 45 landforms divided into seven sections: structural, hydrography, fluvial, gravitative, glacial, nival and anthropic landforms. The use of both legend systems allows us to represent the landform types distributed over an area of 40 km2 and to identify the geomorphic processes involved in their morphogenesis, this variety of processes and landforms identified demonstrated that geomorphological cartography obtained by combining traditional image interpretation and GIS technology facilitates the production of geomorphological maps and the obtaining of valuable data for identify and understand surface processes and landforms. References: Maillard, B., Lambiel, C., Martin, S., Pellitero, R., Reynard, E

  7. Yearly report, Yucca Mountain project

    Energy Technology Data Exchange (ETDEWEB)

    Brune, J.N.


    We proposed to (1) Develop our data logging and analysis equipment and techniques for analyzing seismic data from the Southern Great Basin Seismic Network (SGBSN), (2) Investigate the SGBSN data for evidence of seismicity patterns, depth distribution patterns, and correlations with geologic features (3) Repair and maintain our three broad band downhole digital seismograph stations at Nelson, nevada, Troy Canyon, Nevada, and Deep Springs, California (4) Install, operate, and log data from a super sensitive microearthquake array at Yucca Mountain (5) Analyze data from micro-earthquakes relative to seismic hazard at Yucca Mountain.

  8. Life in the Taihang Mountains

    Institute of Scientific and Technical Information of China (English)


    THE Taihang Mountain Range meanders for 500 kilometers across the territories of Henan, Shanxi and Hebei provinces. It is an important ecological screen for the North China Plain and source of water. In Hebei’s Shexian County sits Wangjinzhuang, a 300-year-old stone village nestled in the mountains.The village is a stone world-lanes, houses, court-yard walls, towers, pavilions, tables, benches and mills are all hewn fom ancient rock. Streets and lanes are paved in stones of various shapes and sizes whose sur-


    Segerstrom, Kenneth; Stotelmeyer, R.B.


    On the basis of a mineral survey the White Mountain Wilderness, which constitutes much of the western and northern White Mountains, New Mexico, is appraised to have six areas of probable mineral potential for base and precious metals. If mineral deposits exist in the wilderness, the potential is for small deposits of base and precious metals in veins and breccia pipes or, more significanlty, the possibility for large low-grade disseminated porphyry-type molybdenum deposits. There is little promise for the occurrence of geothermal energy resources in the area.

  10. The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica (United States)

    Sugden, David E.; Hein, Andrew S.; Woodward, John; Marrero, Shasta M.; Rodés, Ángel; Dunning, Stuart A.; Stuart, Finlay M.; Freeman, Stewart P. H. T.; Winter, Kate; Westoby, Matthew J.


    An elevated erosional trimline in the heart of West Antarctica in the Ellsworth Mountains tells of thicker ice in the past and represents an important yet ambiguous stage in the evolution of the Antarctic Ice Sheet. Here we analyse the geomorphology of massifs in the southernmost Heritage Range where the surfaces associated with the trimline are overlain by surficial deposits that have the potential to be dated through cosmogenic nuclide analysis. Analysis of 100 rock samples reveals that some clasts have been exposed on glacially moulded surfaces for 1.4 Ma and perhaps more than 3.5 Ma, while others reflect fluctuations in thickness during Quaternary glacial cycles. Modelling the age of the glacially moulded bedrock surface based on cosmogenic 10Be, 26Al and 21Ne concentrations from a depth-profile indicates a minimum exposure age of 2.1-2.6 Ma. We conclude that the glacially eroded surfaces adjacent to the trimline predate the Last Glacial Maximum and indeed the Quaternary. Since erosion was by warm-based ice near an ice-sheet upper margin, we suggest it first occurred during the early glaciations of Antarctica before the stepped cooling of the mid-Miocene at ∼14 Ma. This was a time when the interior Antarctic continent had summers warm enough for tundra vegetation to grow and for mountain glaciers to consist of ice at the pressure melting point. During these milder conditions, and subsequently, erosion of glacial troughs is likely to have lowered the ice-sheet surface in relation to the mountains. This means that the range of orbitally induced cyclic fluctuations in ice thickness have progressively been confined to lower elevations.

  11. Rocky Mountain Spotted Fever (For Parents) (United States)

    ... Feeding Your 1- to 2-Year-Old Rocky Mountain Spotted Fever KidsHealth > For Parents > Rocky Mountain Spotted Fever Print A A A What's in ... en español La rickettsiosis maculosa About RMSF Rocky Mountain spotted fever (RMSF) is a bacterial infection that's ...

  12. 49 CFR 71.8 - Mountain zone. (United States)


    ... 49 Transportation 1 2010-10-01 2010-10-01 false Mountain zone. 71.8 Section 71.8 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE BOUNDARIES § 71.8 Mountain zone. The fourth zone, the mountain standard time zone, includes that part of the United States that is west of...

  13. 27 CFR 9.94 - Howell Mountain. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Howell Mountain. 9.94... Howell Mountain. (a) Name. The name of the viticultural area described in this section is “Howell Mountain.” (b) Approved maps. The appropriate maps for determining the boundaries of the Howell...

  14. Storymakers: Hopa Mountain's Early Literacy Program (United States)

    Templin, Patricia A.


    Hopa Mountain's StoryMakers program is an innovative, research-based program for donating high quality young children's books to parents. Hopa Mountain is a nonprofit organization based in Bozeman, Montana. Hopa Mountain works with groups of rural and tribal citizen leaders who form StoryMakers Community Teams to talk one-on-one with local parents…

  15. 27 CFR 9.102 - Sonoma Mountain. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Sonoma Mountain. 9.102... Sonoma Mountain. (a) Name. The name of the viticultural area described in this section is “Sonoma Mountain.” (b) Approved maps. The approved maps for determining the boundary of the Sonoma...

  16. 27 CFR 9.112 - Arkansas Mountain. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Arkansas Mountain. 9.112... Arkansas Mountain. (a) Name. The name of the viticultural area described in this section is “Arkansas Mountain.” (b) Approved maps. The appropriate maps for determining the boundary of the Arkansas...

  17. Magnetic susceptibility variations of carbonates controlled by sea-level changes——Examples in Devonian to Carboniferous strata in southern Guizhou Province,China

    Institute of Scientific and Technical Information of China (English)

    张世红; 王训练; 朱鸿


    This paper presents magnetic susceptibility results of 578 samples from three De-vono-Carboniferous carbonate successions in the Yangtze Block. They indicate that the magnetic susceptibility variations in carbonates are controlled by ancient sea-level changes. It is particularly so if the supply of detrital materials was low, when the magnetic susceptibility was mainly controlled by the content of authigenic minerals. If the supply of detrital materials was high, the average susceptibility value would be higher, but there is still a correlation between susceptibility and sea-level curves. A sea level rise would lead to a decrease in the content of the detrital materials, and therefore to a decrease in the susceptibility values. On the top of HST, the uplift and exposure events may lead to elevated magnetic susceptibility values. Carbonate susceptibilities can therefore be considered as one of the environmental proxy data for the research of sequence stratigraphy.

  18. Magnetic susceptibility variations of carbonates controlled by sea-level changes--Examples in Devonian to Carboniferous strata in southern Guizhou Province, China

    Institute of Scientific and Technical Information of China (English)


    This paper presents magnetic susceptibility results of 578 samples from three Devono-Carboniferous carbonate successions in the Yangtze Block. They indicate that the magnetic susceptibility variations in carbonates are controlled by ancient sea-level changes. It is particularly so if the supply of detrital materials was low, when the magnetic susceptibility was mainly controlled by the content of authigenic minerals. If the supply of detrital materials was high, the average susceptibility value would be higher, but there is still a correlation between susceptibility and sea-level curves. A sea level rise would lead to a decrease in the content of the detrital materials, and therefore to a decrease in the susceptibility values. On the top of HST, the uplift and exposure events may lead to elevated magnetic susceptibility values. Carbonate susceptibilities can therefore be considered as one of the environmental proxy data for the research of sequence stratigraphy.

  19. Multi-method geo- and thermochronology of glacially transported cobbles reveals the tectonic and exhumation history of the St. Elias Mountains (Alaska/Yukon) (United States)

    Falkowski, Sarah; Enkelmann, Eva; Drost, Kerstin; Pfänder, Jörg; Stübner, Konstanze; Ehlers, Todd


    Multi-method dating is a powerful tool to understand tectonic processes and mountain building. In the case of inaccessible mountain regions, e.g., due to extensive glaciation, the dating of detrital material and bedrock samples from rare outcrops with geo- and thermochronologic methods is often the only applicable approach to study the timing and rates of tectonic processes. The St. Elias Mountains of southeast Alaska and southwest Yukon are an example of a heavily glaciated orogen. With the help of detrital thermochronology of sand-sized material, exhumation patterns could be mapped, though with a low spatial resolution. In contrast, geo- and thermochronology applied to glacially derived cobbles yields provenance information from cobble lithology, zircon U-Pb dating, and the entire cooling history from multiple mineral phases. Multi-grain and multi-aliquot analyses yield high-precision crystallization and cooling ages, while sand-sized detritus requires analysis of single minerals particularly resistant to weathering. We present a reconstruction of the Cenozoic tectonic and exhumation history of the St. Elias Mountains that was obtained from the analysis of 27 carefully selected and prepared cobble samples taken from two of the largest glacial catchments of the St. Elias Mountains. A total of 21 zircon U-Pb data sets as well as eight amphibole and seven biotite 40Ar/39Ar ages constrain the (maximum) formation and cooling ages, respectively, of the rocks in the source area. In addition, four zircon and six apatite (U-Th)/He ages as well as four apatite fission-track ages reveal the exhumation history of these source rocks. Integration of the cobble results with an additional three bedrock biotite 40Ar/39Ar ages and published geo- and thermochronologic data from along the St. Elias Mountains reveals details on the timing and rates of the Cenozoic tectonic evolution of the North American margin in southeast Alaska. Documented are the earliest Eocene spreading

  20. A mountain of millipedes V

    DEFF Research Database (Denmark)

    Enghoff, Henrik


    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...

  1. A mountain of millipedes III

    DEFF Research Database (Denmark)

    Enghoff, Henrik


    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. Years Spent on Mountain Roads

    Institute of Scientific and Technical Information of China (English)


    SONG Fangrong, the Tu nationality girl who grew up drinking water from mountain springs, walked into the Great Hall of the People in Beijing to accept the highest prize for China’s youth—the "May 4th Youth Prize." Not long before, she had been named one of the National Ten Outstanding Youths. She is the only individual to have won both.

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

    Directory of Open Access Journals (Sweden)

    Axel Müller


    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.

  4. Relationships between Basic and Silicic Magmatism in Continental Rift Settings: A Petrogeochemical Study of Carboniferous Post-collisional Rift Silicic Volcanics in Tianshan, NW China

    Institute of Scientific and Technical Information of China (English)


    Petrogeochemical data are reported for silicic volcanic rocks from the Tianshan Carboniferous rift, with the aim of discussing the petrogenesis of silicic magmas. Incompatible element vs. incompatible element diagrams display smooth positive trends for the Tianshan Carboniferous rift-related volcanic rocks; the isotope ratios of the silicic lavas [87Sr/86Sr(t)=0.69988-0.70532; εNd(t)=4.76-8.00; 206Pb/204Pb(t)=17.435-18.017; 207Pb/204Pb(t)=15.438-15.509; 208Pb/204Pb(t) = 37.075-37.723] encompass those of the basic lavas. These data suggest a genetic link between rhyolites and basalts, but are not definitive in establishing whether silicic rocks are related to basalts through fractional crystallization or partial melting. Geochemical modeling of incompatible vs. compatible elements excludes the possibility that silicic melts are generated by the melting of basaltic rocks, and indicates a derivation by fractional crystallization plus moderate assimilation of wall rocks (AFC) starting from intermediate rocks to silicic rocks. Continuous AFC from basalt to rhyolite,with small rates of crustal assimilation, best explains the geochemical data. The presence or absence of bimodal volcanism (the "Daly Gap") might be related to cooling rates of magma chambers. In central and eastern Tianshan, the crust was thinner and the cooling rates of the magma chamber within the crust were greater. These conditions resulted in a rapid fall in temperature within the magma reservoir and caused a narrow temperature interval over which intermediate melts formed, effectively reducing the volume of the intermediate melts.

  5. The Capilla del Monte pluton, Sierras de Córdoba, Argentina: the easternmost Early Carboniferous magmatism in the pre-Andean SW Gondwana margin (United States)

    Dahlquist, Juan A.; Pankhurst, Robert J.; Rapela, Carlos W.; Basei, Miguel A. S.; Alasino, Pablo H.; Saavedra,