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13059070 Bagard, Marie-Laure (Université de Strasbourg, Laboratoire d'Hydrologie et de Geochimie de Strasbourg, Strasbourg, France); Schmitt, Anne-Désirée; Chabaux, François; Pokrovsky, Oleg S.; Viers, Jérôme; Stille, Peter; Labolle, François and Prokushkin, Anatoly S. Biogeochemistry of stable Ca and radiogenic Sr isotopes in a larch-covered permafrost-dominated watershed of central Siberia: Geochimica et Cosmochimica Acta, 114, p. 169-187, illus. incl. 5 tables, geol. sketch map, 105 ref., August 1, 2013.
Stable Ca and radiogenic Sr isotope compositions were measured in different compartments (stream water, soil solutions, rocks, soils and soil leachates and vegetation) of a small permafrost-dominated watershed in the Central Siberian Plateau. The Sr and Ca in the area are supplied by basalt weathering and atmospheric depositions, which significantly impact the Sr isotopic compositions. Only vegetation significantly fractionates the calcium isotopes within the watershed. These fractionations occur during Ca uptake by roots and along the transpiration stream within the larch trees and are hypothesised to be the result of chromatographic processes and Ca oxalate crystallisations during Ca circulation or storage within plant organs. Biomass degradation significantly influences the Ca isotopic compositions of soil solutions and soil leachates via the release of light Ca, and organic and organo-mineral colloids are thought to affect the Ca isotopic compositions of soil solutions by preferential scavenging of 40Ca. The imprint of organic matter degradation on the d44/40Ca of soil solutions is much more significant for the warmer south-facing slope of the watershed than for the shallow and cold soil active layer of the north-facing slope. As a result, the available stock of biomass and the decomposition rates appear to be critical parameters that regulate the impact of vegetation on the soil-water system in permafrost areas. Finally, the obtained d44/40Ca patterns contrast with those described for permafrost-free environments with a much lower d44/40Ca fractionation factor between soils and plants, suggesting specific features of organic matter decomposition in permafrost environments. The biologically induced Ca isotopic fractionation observed at the soil profile scale is not pronounced at the scale of the streams and large rivers in which the d44/40Ca signature may be controlled by the heterogeneity of lithological sources. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.gca.2013.03.038
13059028 Vaks, A. (University of Oxford, Department of Earth Sciences, Oxford, United Kingdom); Gutareva, O. S.; Breitenbach, S. F. M.; Avirmed, E.; Mason, A. J.; Thomas, A. L.; Osinzev, A. V.; Kononov, A. M. and Henderson, G. M. Speleothems reveal 500,000-year history of Siberian permafrost: Science, 340(6129), p. 183-186, illus. incl. sketch map, 34 ref., April 12, 2013.
Soils in permafrost regions contain twice as much carbon as the atmosphere, and permafrost has an important influence on the natural and built environment at high northern latitudes. The response of permafrost to warming climate is uncertain and occurs on time scales longer than those assessed by direct observation. We dated periods of speleothem growth in a north-south transect of caves in Siberia to reconstruct the history of permafrost in past climate states. Speleothem growth is restricted to full interglacial conditions in all studied caves. In the northernmost cave (at 60°N), no growth has occurred since Marine Isotopic Stage (MIS) 11. Growth at that time indicates that global climates only slightly warmer than today are sufficient to thaw extensive regions of permafrost.
DOI: 10.1126/science.1228729
13058582 Iglovskiy, S. A. (Russian Academy of Sciences, Institute of Northern Regions Ecology, Arkhangelsk, Russian Federation). Antropogennye izmeneniya merzlotnykh usloviy yevropeyskogo severa i ikh posledstviya [Anthropogenic change of permafrost and its effects in the European part of northern Russia]: Geoekologiya (Moskva), 2013(1), p. 53-60 (English sum.), 34 ref., February 2013.
The anthropogenic changes of permafrost are studied at the key sites in the European North, i.e., Koida settlement (Mezenskaya tundra), Nes settlement (Kanin peninsula), Shoina settlement (Kanin peninsula), Mezen settlement, lakes Vashutkini (Bol'shezemel'skaya tundra), Amderma (Yugorsky peninsula), and the northern part of the Vaigach island. Geocryological characteristics of sites are provided, and the main types of anthropogenic changes in permafrost conditions are described.
13061412 Hall, Kevin (University of Northern British Columbia, Geography Programme, Prince George, BC, Canada). Periglacial processes and landforms of the Antarctic; a review of recent studies and directions: in Antarctic palaeoenvironments and earth-surface processes (Hambrey, M. J., editor; et al.), Special Publication - Geological Society of London, 381, illus. incl. sketch map, 189 ref., July 1, 2013. (Online First).
The wide range of periglacial environments of the Antarctic, from the wet, mild oceanic sub-Antarctic through to the cold, dry continent, provides not only an extensive modern laboratory, but also one that offers insights into conditions in the Northern Hemisphere at the height of the last glacial, is an analogue for periglacial conditions on other planets, and can be used for monitoring climatic change. Almost the whole known suite of periglacial landforms is present. Recent research directions show strong linkages between the biotic components and the abiotic responses, offering new insights into periglacial synergies and hence landform development. Other new directions are those of using the Antarctic as an analogue for periglacial conditions on Mars, and multinational undertakings monitoring permafrost and active layer changes. During the past three decades there have been a number of reviews of periglacial landforms and processes for both the area as a whole as well as for specific locations or regions. Here information regarding material post-dating the most recent reviews is provided and an attempt is made to highlight new directions and findings. This broad-based review provides a foundation for more detailed accounts on some of the periglacial attributes provided in other papers within these volumes.
DOI: 10.1144/SP381.16
13058585 Yastrebov, A. A. (Russian Academy of Sciences, Ye. Sergeyev Institute of Geoecology, Moscow, Russian Federation) and Mamayev, Yu. A. Zadachi geoekologicheskoy otsenki sostoyaniya podzemnykh vod eotsen-chetvertichnogo vodonosnogo kompleksa territorii Yamalo-Nenetskogo avtomnogo okruga v svyazi s razrabotkoy mestorozhdeniy uglevodorodov [Problems of geoecological analysis of ground water in Eocene-Quaternary aquifers in the Yamal-Nenets region with regard to oil and gas field development]: Geoekologiya (Moskva), 2013(1), p. 80-84 (English sum.), 1 table, sketch map, 7 ref., February 2013.
The paper shows that the regional regularities of spatial variability in geocryological conditions in the Yamal-Nenetz autonomous okrug, the permafrost massif structure, cryogenic processes and related hummocky-depressional relief, in particular, control the areal trend in runoff parameters of Eocene-Quaternary aquifer as well as pollutant migration within the region. Assessment of geosystem resistance to technogenic impact with the account of global climate warming and degrading permafrost should be based on water-balance calculation taking into consideration the depth and capacity parameters of water bodies.
13059089 Narloch, Wlodzimierz (Nicolaus Copernicus University, Department of Geology and Hydrogeology, Torun, Poland); Wysota, Wojciech and Piotrowski, Jan A. Sedimentological record of subglacial conditions and ice sheet dynamics of the Vistula ice stream (north-central Poland) during the last glaciation: Sedimentary Geology, 293, p. 30-44, illus. incl. sketch maps, 106 ref., July 1, 2013.
Deposits of the Vistula Ice Stream draining the Scandinavian Ice Sheet during the Last Glaciation were investigated at four field sites in north-central Poland using micro- and macroscale features. The study reveals several till units with specific structural, textural and lithological characteristics. The individual till units are either macroscopically massive or bedded, and the contacts between the units are either sharp or transitional. The nature of the contacts with the underlying sediments, ductile deformation structures, largely undeformed clayey clasts, tectonic lamination, thin horizontal stringers of sorted sediments, ploughing marks, boulder pavements, and striated upper surfaces of pebbles in the till indicate both bed deformation and enhanced basal sliding under high subglacial water pressure conditions. It is suggested that the till is a hybrid deposit generated by some combination of lodgement, deformation and ploughing punctuated by periods of basal decoupling. The depth of deformation at any point in time was thinner (up to several decimetres) than the maximum till thickness (c. 2.5 m). The ice sliding velocity estimations indicate velocities of less than 100 to over 2000 m yr-1, which suggests an unstable and highly dynamic ice lobe, consistent with spatial variability of till characteristics. Sand wedges in the deposits beneath the till and the nature of the till/bed interface indicate permafrost under the advancing ice sheet. We suggest that under the increasing ice thickness, a layer of thawed, water-saturated sediment formed on top of the still-frozen ground due to inefficient drainage, and contributed to ice streaming by promoting pervasive deformation and basal sliding. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.sedgeo.2013.05.001
13059394 Ueta, Akihiro (Hokkaido University, Graduate School of Earth Environmental Science, Sapporo, Japan); Sugimoto, Atsuko; Iijima, Yoshihiro; Yabuki, Hironori; Maximov, Trofim C.; Velivetskaya, Tatiana A. and Ignatiev, Alexander V. Factors controlling diurnal variation in the isotopic composition of atmospheric water vapour observed in the taiga, eastern Siberia: Hydrological Processes, 27(16), p. 2295-2305, illus. incl. 1 table, sketch map, July 30, 2013.
Deciduous forest covers vast areas of permafrost under severe dry climate in eastern Siberia. Understanding the water cycle in this forest ecosystem is quite important for climate projection. In this study, diurnal variations in isotopic compositions of atmospheric water vapour were observed in eastern Siberia with isotope analyses of precipitation, sap water of larch trees, soil water, and water in surface organic layer during the late summer periods of 2006, 2007, and 2008. In these years, the soil moisture content was considerably high due to unusually large amounts of summer rainfall and winter snowfall. The observed sap water d18O ranged from -17.9 ppm to -13.3 ppm, which was close to that of summer precipitation and soil water in the shallow layer, and represents that of transpired water vapour. On sunny days, as the air temperature and mixing ratio rose from predawn to morning, the atmospheric water vapour d18O increased by 1 ppm to 5 ppm and then decreased by about 2 ppm from morning to afternoon with the mixing ratio. On cloudy days, by contrast, the afternoon decrease in d18O and the mixing ratio was not observed. These results show that water vapour that transpired from plants, with higher d18O than the atmospheric water vapour, contributes to the increase in d18O in the morning, whereas water vapour in the free atmosphere, with lower d18O, contributes to the decrease in the afternoon on sunny days. The observed results reveal the significance of transpired water vapour, with relatively high d18O, in the water cycle on a short diurnal time scale and confirm the importance of the recycling of precipitation through transpiration in continental forest environments such as the eastern Siberian taiga. Abstract Copyright (2010), John Wiley & Sons, Ltd.
DOI: 10.1002/hyp.9361
13059058 Balks, Megan R. (University of Waikato, Department of Earth and Ocean Sciences, Hamilton, New Zealand); López-Martínez, Jerónimo; Goryachkin, Sergey V.; Mergelov, Nikita S.; Schaefer, Carlos E. G. R.; Simas, Felipe N. B.; Almond, Peter C.; Claridge, Graeme G. C.; McLeod, Malcolm and Scarrow, Joshua. Windows on Antarctic soil-landscape relationships; comparison across selected regions of Antarctica: in Antarctic paleoenvironments and earth-surface processes (Hambrey, M. J., editor; et al.), Special Publication - Geological Society of London, 381, illus. incl. 2 tables, geol. sketch map, 44 ref., May 16, 2013. (Online First).
This paper brings together topographic cross-section "windows" from across Antarctica to illustrate soil-landscapes from the margins of the polar plateau in the Transantarctic Mountains and McMurdo Dry Valleys, through East Antarctic coastal areas, to the northern Antarctic Peninsula Region. Soils identified range from Gelisols in the Ross Sea Region, through Gelisols and Entisols in coastal East Antarctica, to a mixture of Gelisols, Entisols, Spodosols and Inceptisols in the northern Antarctic Peninsula Region where permafrost is not ubiquitous. The relative impacts of the soil-forming factors are considered. At a continental scale climate is the main driver of the differences observed between soils in different areas. At local scales strong soil-topographic relationships are observed. Organisms, time and parent material are dominant influences on soil properties only in relatively localized situations. Organisms dominate in areas of organic matter or guano accumulation and time is a dominant influence on exceptionally old upland surfaces in the McMurdo Dry Valleys. The US Department of Agriculture"s Soil Taxonomy gives a useful overall appraisal of Antarctic soils; however, for detailed work, there is a need to introduce some new categories at subgroup level to better capture the range of soils described.
DOI: 10.1144/SP381.9
13059371 Mustaphi, Colin J. Courtney (University of Ottawa, Laboratory for Paleoclimatology and Climatology, Ottawa, ON, Canada) and Gajewski, Konrad. Holocene sediments from a coastal lake on northern Devon Island, Nunavut, Canada: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, 50(5), p. 564-575, illus. incl. 3 tables, sketch map, 58 ref., May 2013.
Sediment cores from Lake DV09, northern Devon Island, Nunavut, Canada (75°34'34"N, 89°18'55"W), were studied to reconstruct the lake ontogeny through analysis and interpretation of the sediment stratigraphy. The lake was uplifted from marine inundation ~7600 cal BP. After a millennium of rapid sediment accumulation, which coincided with the Holocene Thermal Maximum in the region, accumulation rates decreased over the past 6000 years as the Arctic became colder. This resulted in the deposition of very fine laminae that were interpreted as varves. The uppermost laminated sediments provided a ~1600 year history of annual sediment transport and deposition into the lake. During periods of warmer temperatures, such as between 6000 and 7500 cal BP and during the Medieval Climate Anomaly (~950-1300 CE; CE, Christian Era), hydroclimatic and permafrost slope processes increased sedimentation rates into the basin.
DOI: 10.1139/cjes-2012-0143
13061417 Marchant, D. R. (Boston University, Department of Earth and Environment, Boston, MA); Mackay, S. L.; Lamp, J. L.; Hayden, A. T. and Head, J. W. A review of geomorphic processes and landforms in the Dry Valleys of southern Victoria Land; implications for evaluating climate change and ice-sheet stability: in Antarctic palaeoenvironments and earth-surface processes (Hambrey, M. J., editor; et al.), Special Publication - Geological Society of London, 381, illus. incl. 2 tables, sketch map, 224 ref., July 1, 2013. (Online First).
The Dry Valleys are subdivided into three microclimate zones on the basis of summertime measurements of atmospheric temperature, soil moisture, relative humidity and wind-speed/ direction. Subtle variations in these climate parameters result in considerable differences in process geomorphology and in the development of unique landforms within each zone. The mapped zones include a coastal thaw zone, an inland mixed zone and a stable upland zone. Landforms within each zone are subdivided into macroscale features (e.g. valleys, slopes and gullies), mesoscale features (e.g. polygons and viscous-flow features) and microscale features (e.g. rock and near-surface soil features, including the effects of salt weathering, wind erosion and pitting). We present a review of landscape development in the Dry Valleys with implications for long-term climate change and ice-sheet stability. Chronological control is afforded by 40Ar/39Ar dating of volcanic ash-fall deposits and cosmogenic nuclide analyses of surface boulders. Collectively, the data call for persistent cold and dry conditions in the stable upland zone for approximately the last 14 Ma, although some level of climatic amelioration and landform modification may have occurred within low-lying regions and in the inland mixed zone.
DOI: 10.1144/SP381.10
13060558 Cao Jiansheng (Chinese Academy of Sciences, Institute of Genetics and Developmental Biology, Shijiazhuang, China); Liu Changming and Zhang Wanjun. Response of rock-fissure seepage to snowmelt in Mount Taihang slope-catchment, North China: Water Science and Technology, 67(1), p. 124-130, illus. incl. sketch map, 23 ref., 2013.
The complex physiographic and hydrogeological systems of mountain terrains facilitate intense rock-fissure seepages and multi-functional ecological interactions. As mountain eco-hydrological terrains are the common water sources of river basins across the globe, it is critical to build sufficient understanding into the hydrological processes in this unique ecosystem. This study analyzes infiltration and soil/rock-fissure seepage processes from a 65 mm snowfall/melt in November 2009 in the typical granitic gneiss slope catchment in the Taihang Mountains. The snowfall, snowmelt and melt-water processes are monitored using soil-water time-domain reflectometry (TDR) probes and tipping bucket flowmeters. The results suggest that snowmelt infiltration significantly influences soil/rock water seepage in the 0-100 cm soil depth of the slope-catchment. It is not only air temperature that influences snowmelt, but also snowmelt infiltration and rock-fissure seepage. Diurnal variations in rock-fissure seepage are in close correlation with air temperature (R2>0.7). Temperature also varies with soil/rock water viscosity, which element in turn influences soil/rock water flow. Invariably, water dynamics in the study area is not only a critical water supply element for domestic, industrial and agricultural uses, but also for food security and social stability.
DOI: 10.2166/wst.2012.542
13067299 Davydov, V. A. (Russian Academy of Sciences, Uralian Division, Institute of Geophysics, Yekaterinburg, Russian Federation) and Bakayev, V. P. Geofizika na rossypnykh mestorozhdeniyakh zolota [Geophysics at gold placer deposits]: Razvedka i Okhrana Nedr, 2012(4), p. 41-47 (English sum.), illus., 6 ref., April 2012.
Geophysical researches are described by prospecting and investigation of gold placers deposits. Examples of solved problems on different genetic types of placers are presented, and recommendations for integration of geophysical methods are given.
13065300 Griener, Kathryn W. (Louisiana State University, Department of Geology and Geophysics, Baton Rouge, LA); Nelson, David M. and Warny, Sophie. Declining moisture availability on the Antarctic Peninsula during the late Eocene: Palaeogeography, Palaeoclimatology, Palaeoecology, 383-384, p. 72-78, illus., 65 ref., August 2013. Supplemental information/data is available in the online version of this article.
Paleobotanical data have indicated that the Antarctic landscape shifted from a beech (Nothofagus)-dominated forest to a more sparsely vegetated taiga-like woodland and tundra during the Late Eocene, coincident with progressive cooling and glacial growth. Reduced moisture availability may have contributed to this vegetation change, but there is limited evidence for assessing the Late Eocene hydrologic regime. We evaluated the relationship between Nothofagus d13C and moisture availability by determining d13C of modern Nothofagus pollen, sporopollenin, and leaves and comparing these results to precipitation data. To assess plant moisture availability and vegetation composition just prior to the Eocene-Oligocene boundary, we measured d13C of fossil Nothofagus sporopollenin (Nothofagidites) from the SHALDRIL 3C cores (which date to ~35.9 My) and evaluated these results in the context of temporal variation in pollen assemblages from the same sediments. Values of carbon isotope discrimination (D) for modern Nothofagus sporopollenin range between 18.1 and 22.4 ppm. These values are positively correlated with precipitation amount, as well as pollen and leaf D, which suggests that fossil sporopollenin D records the level of plant moisture availability. D values obtained from Nothofagidites sporopollenin from the SHALDRIL 3C sediments range between 17.9 and 20.2 ppm and generally decline through time. These results suggest a decrease in plant moisture availability on the Antarctic Peninsula during the Late Eocene, perhaps as a result of declining precipitation and/or soil moisture. Therefore, moisture stress experienced by Nothofagus likely contributed to the shift to a more sparsely vegetated Late Eocene landscape. Our results show that carbon isotopic analysis of pollen from C3 plants may aid understanding how variations in moisture availability contribute to shifts in plant community composition in the paleorecord. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.palaeo.2013.05.004
13059132 Poros, Zsofia (Eotvos Lorand University, Budapest, Hungary); Machel, Hans G.; Mindszenty, Andrea and Molnar, Ferenc. Cryogenic powderization of Triassic dolostones in the Buda Hills, Hungary: International Journal of Earth Sciences = Geologische Rundschau, 102(5), p. 1513-1539, illus. incl. 6 plates, 2 tables, geol. sketch map, 80 ref., July 2013.
Disintegration of dolostones to dolomite powder (powderization) was a widespread phenomenon in Triassic dolostones of the Buda Hills, where the areal extent of powdered dolostones is large compared to similar occurrences elsewhere in the world. In the Buda Hills, dolostone disintegration proceeded in four stages that correspond to a gradual decrease in particle size, that is, from the parent dolostone to (1) crackle breccia; via (2) mosaic breccia (diameter <2 cm); via (3) mosaic breccia blocks 'floating' in dolomite powder; to (4) dolomite powder (diameter 100-300 mm). Stable isotope ratios and trace element compositions of dolomite remained constant throughout these stages, and there are no indications of dissolution in most locations, suggesting that disintegration was predominantly a mechanical process. Combining these findings with the geological history of the region, and supported by a simple freezing/thawing experiment and pertinent experimental studies on weathering of building stones, it appears that powderization in the Buda Hills was caused by repeated freeze-thaw cycles during and/or after the Pleistocene glaciations. Subaerial exposure under cold climate conditions involves multiple freeze-thaw cycles that create mechanical stresses in the rock framework related to the opposing thermal expansion of rock and water that freezes and of ice that liquefies. This process is herewith called 'cryogenic powderization'. Our data further suggest that the synergy of four factors promoted dolostone powderization in the Buda Hills: (1) tectonics, which created a pervasive fracture network; (2) intercrystalline porosity of the dolostone; (3) relatively high water saturation; and (4) subaerial exposure under cold climate conditions. Copyright 2013 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s00531-013-0883-7
13067499 Han Lijian (Chinese Academy of Sciences, Research Center for Eco-Environmental Sciences, Beijing, China); Tsunekawa, Atsushi and Tsubo, Mitsuru. Shifting of frozen ground boundary in response to temperature variations at northern China and Mongolia, 2000-2007: International Journal of Climatology, 33(7), p. 1844-1848, illus. incl. 1 table, sketch map, 16 ref., June 15, 2013.
Little is known about the shifts of frozen ground boundary in response to temperature variations in the East Asia. We therefore examined the relationship between changes of frozen ground boundary and temperature at northern China and Mongolia. Significant relationships were found between the boundaries' shifting and monthly average air temperature in northeast of China and in the northeast of Mongolia, where the higher temperature resulted in the more northward boundary of frozen ground. However, no significant relationship was found in northwest of Mongolia, in west of China, and in the west of Tibetan Plateau. These results indicate that the temperature is not the major factor in driving the boundary of seasonally frozen ground shifting at typical mid-latitude areas in Asia. This research demonstrates seasonally frozen ground dynamic response to climatic change at some mid-latitude areas where seasonally frozen ground boundary shifting would be utilized as an additional factor for tracking climatic change. Abstract Copyright (2013), Royal Meteorological Society.
DOI: 10.1002/joc.3708
13065237 Romankevich, E. A. (Russian Academy of Sciences, Shirshov Institute of Oceanology, Moscow, Russian Federation) and Vetrov, A. A. Masses of carbon in the Earth's hydrosphere: Geochemistry International, 51(6), p. 431-455, June 2013. Based on Publisher-supplied data.
Recent data were summarized on the concentration and mass of inorganic and organic carbon in reservoirs of the Earth's hydrosphere. We compared carbon masses and accumulation conditions in the surface hydrosphere and waters of the sedimentary shell and proportions between carbonate, dissolved, and suspended particulate organic carbon. It was shown that the total masses of carbon in the surface hydrosphere and in the waters of the sedimentary shell are approximately equal to 80 ´ 1018 g C at an organic to carbonate carbon ratio of 1 : 36 and 1 : 43, respectively. Three main forms of organic compounds in the ocean (living organisms, suspended particles, and dissolved species) occur in the proportion 1 : 13 : 250 and form the pyramid of masses 4 ´ 1015 g, 50 ´ 1015 g, and 1000 ´ 1015 g Corg. The descending sequence of the organic to carbonate carbon ratio in water, ocean (1 : 36) > glaciers (1 : 8) > lakes (1 : 2) > rivers (1 : 0.6) > wetlands (1 : 0.3), is in general consistent with an increase in the same direction in the mean concentrations of organic matter: 0.77 mg Corg/L in the ocean, 0.7 mg Corg/L in glaciers, 6-30 mg Corg/L in lakes, 15 mg Corg/L in rivers, and 75 mg Corg/L in wetlands. Both the mean concentrations and masses of dissolved organic matter in the pore waters of oceanic sediments and in the waters of the sedimentary shell are similar: 36-37 mg/L and 5 ´ 1018 and 5.6 ´ 1018 g, respectively. The mass of carbonate carbon in the pore waters of the ocean, (19-33) ´ 1018 g, is comparable with its mass in the water column, 38.1 ´ 1018 g. Copyright 2013 Pleiades Publishing, Ltd.
DOI: 10.1134/S0016702913060062
13063203 Girard, Lucas (University of Zurich, Department of Geography, Zurich, Switzerland); Gruber, Stephan; Weber, Samuel and Beutel, Jan. Environmental controls of frost cracking revealed through in situ acoustic emission measurements in steep bedrock: Geophysical Research Letters, 40(9), p. 1748-1753, illus., 40 ref., May 16, 2013.
Frost cracking, the breakdown of rock by freezing, is one of the most important mechanical weathering processes acting on Earth's surface. Insights on the mechanisms driving frost cracking stem mainly from laboratory and theoretical studies. Transferring insights from such studies to natural conditions, involving jointed bedrock and heterogeneous thermal and hydrological properties, is a major challenge. We address this problem with simultaneous in situ measurements of acoustic emissions, used as proxy of rock damage, and rock temperature/moisture content. The 1 year data set acquired in an Alpine rock wall shows that (1) liquid water content has an important impact on freezing-induced rock damage, (2) sustained freezing can yield much stronger damage than repeated freeze-thaw cycling, and (3) that frost cracking occurs over the full range of temperatures measured extending from 0 down to -15°C. These new measurements yield a slightly different picture than previous field studies where ice segregation appears to play an important role. Abstract Copyright (2013), . American Geophysical Union. All Rights Reserved.
DOI: 10.1002/grl.50384
13067318 Golovin, A. A. (Institute of Rare Elements Mineralogy, Geochemistry and Crystal Chemistry, Moscow, Russian Federation); Gulyayeva, N. G.; Kal'yeva, O. P. and Kolotov, B. A. Vyyavleniye i otsenka zagryazneniya okruzhayushchey sredy toksichnymi khimicheskimi elementami na osnove mnogotselevogo geokhimicheskogo kartirovaniya [Analysis of environmental pollution with toxic chemical elements based on geochemical mapping]: Razvedka i Okhrana Nedr, 2012(7), p. 57-61 (English sum.), illus. incl. sketch map, 9 ref., July 2012.
The technology of multipurpose geochemical mapping (MPGM) developed in Russia provides geochemical data on the complex conjugate of environmental components (bedrock, stream sediments, soil, water, plants). Eco-geochemical maps aimed at identifying the components of the modern structure of the environmental pollution and the environmental condition of the territories subjected to anthropogenic pressure. The results proved the possibility of MPGM use in this technology in eco-geochemical assessment of areas of various economic development.
13067313 Ozerskiy, A. Yu. (Krasnoyarskgeologiya, Krasnoyarsk, Russian Federation). Geokhimicheskiye osobennosti nizhnearkheyskikh porod na uchastke veroyatnogo podzemnogo stroitel'stva v yuzhnoy chasti Yeniseyskogo kryazha [Geochemical characteristics of lower Archean rocks at a possible underground construction site in the southern Yenisei Ridge]: Razvedka i Okhrana Nedr, 2012(7), p. 39-44 (English sum.), illus. incl. 2 tables, 10 ref., July 2012.
Environmental geochemical features of lower Archean rocks investigated for underground building of radioactive wastes isolation are shown. The building of an underground object can't cause landscapes' chemical pollution but drainage discharge into surface water demands cleaning.
13058305 Itoh, Hideyuki (Iwate Prefectural University, Iwate, Japan); Yoshida, Mario; Nagayama, Takahiko; Wakiyama, Kanji; Harada, Norikuni and Nanri, Tomoyuki. Experimental study on the factors leading to unique hydrography of snowmelt-type volcanic mudflow caused by covering of pyroclastic materials: Shin Sabo = Journal of the Japan Society of Erosion Control Engineering, 65(1), p. 47-53, (Japanese) (English sum.), illus. incl. 1 table, 17 ref., May 2012.
Snowmelt-type mudflow is often observed when a pyroclastic flow, surge, blast or a hot-debris avalanche moves over a snow-covered slope. We constructed the experimental equipment to simulate snowmelt due to high-temperature rock fragments moving over a snow-covered channel. The experiments were carried out for nine different cases, changing the parameters of temperature, rock particle diameter, and snow density. On comparing the hydrographs of these nine cases,we found that the following conditions lead to rapid snowmelt and large peak flow: (1) the temperature of the pyroclastic material is sufficiently high; (2) the snow density is remarkably high, as in the case of solid ice; and (3) snow is saturated with liquid water, as in the case of slush. The results indicate that the volume of the snowmelt-type mudflow particularly depends on the snow density and the temperature of the pyroclastic materials.
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13062928 Williams, Kevin K. (Buffalo State College, Department of Earth Sciences and Science Education, Buffalo, NY); Haltigin, Timothy W. and Pollard, Wayne H. Peering into the subsurface; using ground penetrating radar to study ice wedge geometry [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 65, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
In continuous permafrost environments, polygonal terrain is often evidence of subsurface ice wedges. It has been estimated that these environments can contain wedge ice in over 30 percent of the top meter of ground. Being the surface expression of ice wedges, polygons have a variety of appearances which can depend on the surface materials and the subsurface ice wedge geometry. Because polygonal terrain is widespread in permafrost environments and has been observed on Mars, this project uses ground penetrating radar (GPR) to help characterize the shapes and volumes of ice wedges. Although part of a larger study of using geophysical methods to detect ground ice, these results focus on data collected at two locations on Devon Island - a site that has also been used as a Mars analog. Polygon surface troughs on Devon Island vary from narrow depressions to those more than a meter wide. Although subsurface ice was not found beneath every trough, polygons with more notable troughs contain fairly large ice wedges. The two sites studied here have different surface materials, allowing for comparisons of polygon appearances in fine sediments to those in gravel deposits. A GSSI SIR-3000 GPR system was used to collect data at 200 and 400 MHz. These data show the depth to the active layer, the widths of the ice wedges, and other subsurface stratigraphic features very well. Locations and widths of wedge ice were confirmed by augering and trenching to the tops of a sample of the ice wedges. GPR data reveal the ice wedges and clearly delineate their edges. This allows a fairly accurate estimate of the ice wedge widths. Interestingly, surface tensional cracks at one location correlate with wedge edges detected in the GPR data. The tensional cracks are likely due to subsidence that may result from downward melting of the ice wedge in response to increasing temperatures over several years or more. As a surface indicator of active layer thickening, these tensional cracks can be useful for studying past and current climate change in Arctic regions. Additionally, by better understanding the relationship between surface expression and subsurface ice volume, the surface characteristics of polygonal terrain may be used to predict locations and volumes of subsurface ice on Earth and on Mars.
13062591 Moscardelli, Lorena G. (Bureau of Economic Geology, Austin, TX); Dooley, Tim P.; Dunlap, Dallas B.; Wood, Lesli and Jackson, Martin P. Deepwater polygonal fault systems as terrestrial analogs for Martian polygonal terrains [abstr.]: in 2012 AAPG annual convention & exhibition; abstracts volume; Directing the future of E&P; starring creative ideas and new technology, Abstracts: Annual Meeting - American Association of Petroleum Geologists, 2012, unpaginated, 2012. WWW, compact disc. Meeting: 2012 AAPG annual convention & exhibition, April 22-25, 2012, Long Beach, CA.
Discovery of polygonal terrains on Mars has prompted a thirty-year debate over how these features formed. The prevailing hypothesis is that Martian polygonal terrains formed by thermal contraction similar to that in terrestrial permafrost environments. However, seismic-reflection data also reveal the existence of polygonal fault systems in terrestrial Deepwater environments worldwide. How Deepwater polygonal fault systems form is still debated but similarities between Deepwater polygons and Martian polygons suggest that polygonal terrains on the northern plains of Mars could have formed subaqueously. The presence of calcium carbonate, aqueous minerals, and salts on the polygonal bearing Phoenix landing site also supports our subaqueous hypothesis. Physical models indicate that multidirectional extension can generate disaggregation of polygonal features under the influence of a slope and a mobile substrate. These findings support the idea of a Late Hesperian-Early Amazonian ocean on the northern plains of Mars.
URL: http://www.searchanddiscovery.com/abstracts/html/2012/90142ace/abstracts/mosc2.h ...
13063096 Drucker, D. G. (Universität Tübingen, Forschungsbereich Paläobiologie, Tubingen, Germany); Bridault, A. and Cupillard, C. Environmental context of the Magdalenian settlement in the Jura Mountains using stable isotope tracking (13C, 15N, 34S) of bone collagen from reindeer (Rangifer tarandus): in The Magdalenian settlement of Europe (Straus, Lawrence Guy, editor; et al.), Quaternary International, 272-273, p. 322-332, illus. incl. 3 tables, sketch maps, 71 ref., September 12, 2012. Meeting: 27th International Union for Quaternary Research congress; symposium on Quaternary sciences; the view from the mountains, July 21-27, 2011, Bern, Switzerland.
The Jura Mountains are considered to be a region where phases of ice cap extension and retreat in response to climatic variation during the Upper Pleniglacial and Lateglacial (ca. 24,000-12,800 cal BP) are well reflected in the vegetation and animal spectrum composition. A new set of direct AMS radiocarbon dates of collagen from reindeer (Rangifer tarandus) bones found at archaeological sites indicated an almost continuous occupation of the Jura region since the end of Last Glacial Maximum, at ca. 24,000 cal BP, until its local disappearance around 14,000 cal BP. To investigate a possible change in reindeer ecology, isotopic analysis of carbon, nitrogen, sulfur in collagen (d13Ccoll, d15Ncoll, d34Scoll) were performed on the dated specimens. A decrease in the d13Ccoll and d15Ncoll values of Jura reindeer was found at the beginning of the Lateglacial period around 16,300-15,600 cal BP. While the change in d13Ccoll values was better explained by a change in diet composition with a decreasing input of lichens, the relative low d15Ncoll values of the reindeer during the Lateglacial was consistent with a geographical pattern of soil maturity inherited from the Last Glacial Maximum. The same pattern was also seen in the d15Ncoll values of the Lateglacial horse (Equus sp.) and red deer (Cervus elaphus) until ca. 14,000 cal BP. The decrease in reindeer d15Ncoll around 16,300-15,600 cal BP and around 21,000-20,000 cal BP in the Jura region may be linked to the occupation of territories recently released by glaciers that formed during the Heinrich event 1 and the Last Glacial Maximum, respectively. The associated high d15Ncoll and d34Scoll values found in two specimens indicate the occurrence of areas of high soil activity in a globally cold context. This might correspond to the occupation of refugia in the close surroundings of the Jura region. Such local refugia could explain the capacity of the reindeer to occupy rapidly the newly available territories during phase of glacier retreat. The intensification of the Magdalenian human settlement could have been favored by these local ecosystem expansions. Abstract Copyright (2012) Elsevier, B.V.
DOI: 10.1016/j.quaint.2012.05.040
13067966 Peuraniemi, V. (University of Oulu, Department of Geosciences, Oulu, Finland) and Eskola, T. Glacial dispersal and mode of occurrence of metals in till and esker gravel at Kumpuselka, northern Finland: in Geochemistry; exploration, environment, analysis (Hall, G. E. M., editor; et al.), Geochemistry - Exploration, Environment, Analysis, 13(3), p. 195-203, illus. incl. 2 tables, geol. sketch map, 43 ref., August 2013. Meeting: IAGS Finland 2011, 2011, Finland.
A Cu-Zn-Pb-Au mineralized quartz-carbonate vein within micaceous schist recently exposed in a gravel pit quarried into the Kumpuselka esker (Finland) was the impetus of this study, which examines the glacial dispersal of metals in the nearby Quaternary deposits. The oldest ice flow direction in the area was to the SE-SSE, the younger flow in the ice lobe phase to the ESE and the youngest flow to the ENE. Five till and three esker gravel samples were taken for geochemical and heavy mineral studies. The concentrations of base metals in the conventional fine fraction analysis of the till samples are at background level although the samples had been taken from the very proximal part of the glacial dispersal train. Copper and Pb contents in the fine fraction of esker gravel are at higher levels than those in till fines. Base metal sulphides as chalcopyrite, sphalerite, galena and pyrite were found as some separate grains in the heavy mineral concentrates of till. More often, the Cu, Zn and Pb sulphides occur as tiny inclusions in the coarse pyrite grains. Heavy mineral concentrates of the esker gravel contain abundant pyrite grains, but no visible Cu, Zn or Pb sulphides were recovered. In one heavy mineral concentrate of till (KUM 4), Ni-bearing cobaltite and Co-bearing arsenopyrite along with pyrite, chalcopyrite and sphalerite were found. Sulphide minerals have survived even within the upper C-horizon of the till above the groundwater level and therefore sulphide minerals can be used for prospecting sulphide ores by indicator mineral methods. Some chromite grains were also found in the heavy mineral concentrates of the till samples. Their presence reflects multi-phase, long-distance glacial transport (100 km) of the older till material which have subsequently been inherited by the younger till.
DOI: 10.1144/geochem2012-156
13064929 Aldred, Jennifer L. (University of North Carolina, Department of Geography and Earth Sciences, Charlotte, NC); Eppes, M. C.; Diemer, John A.; Wright, Sam and Abernathy, Stephen. Post glacial evolution of subalpine hillslopes and soils, SE San Juan Mountains, CO, USA [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 93, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
Previous research conducted in the Conejos River basin suggests that some hillslopes in this subalpine landscape have been relatively stable since 9837 ± 72 cal. years B.P.; based on radio carbon dates and the presence of well developed soil profiles on lower elevation portions of valley interfluves (Layzell et al., 2012). Alluvial fans and fluvial terraces in the axial valley adjacent to these slopes, however, were aggrading episodically throughout the Holocene; (Johnson, 2011; Layzell et al., 2012). These data suggests that sediment involved in valley bottom aggradation is likely derived from spatially distinct hillslope sources during temporally distinct climatic events. However, the processes and spatial and temporal variables controlling from where and when sediment is originating are unknown. Here we use soil development as a proxy for hillslope stability in order to test the role of landscape position on erosion in subalpine environments. The geomorphic features and deposits of Sawmill Gulch, a tributary drainage basin of the Conejos River, were mapped and divided into 14 mapping units based on surface geomorphology, deposit type, vegetation and slope. We hand-dug a total of 28 soil pits (a minimum of 2 per mapping unit) in the basin. Soil was sampled from each soil horizon in every pit. To determine the variability of parent material with depth in terms of rock type, roundness, mineralogy, and degree of weathering a clast count of 30 rocks was performed in each pit at 5 cm down and 10-20 cm across, depending on the abundance of clasts in the pit face. Soils varied predictably as a function of landscape unit which varied at small spatial scales (50m or less); with some map units exhibiting well developed soils with strong structure and color. These data suggest that erosion since deglaciation has been limited to certain types of slopes and deposits. For example, shallow forested (conifer) moraine features most commonly exhibit the weakest soil development suggesting that these positions are least stable over Holocene time scales. An abundance of charcoal was found in soil pits throughout Sawmill Gulch. Future work will attempt to determine the key characteristics and processes that result in preferential erosion of certain landscape positions over others.
13062923 Soare, Richard J. (Dawson College, Department of Geography, Montreal, QC, Canada); Conway, Susan J. and Dohm, James M. Evidence of landscape modification in and around the Argyre impact basin, Mars, by "wet" periglacial processes [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 64, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
We have used all relevant HiRISE, MOC, THEMIS and CTX images in and around the Argyre impact basin (AIB; ~30-70°S; ~300-160°E), Mars, to identify and then map a close spatial-assemblage of three landforms whose origin could be indicative of an ice-rich and thaw-modified (regional) regolith: (a) polygonised terrain comprised of unsorted and small-sized polygons (~150 m in diameter); (b) putative (relict) debris-flows (kms in length); and, (c) mantled terrain (extant in some instances, dissected in others). Heretofore, the possible connexion between each of these landforms and the occurrence of an ice-rich landscape at the northern or southern mid-latitudes of Mars has been debated by numerous workers; whether thaw has contributed to the formation or modification of these landscapes has been a question of ongoing interest and of far-reaching consequence. Here we present and discuss the occurrence of low-centred polygons (a polygon sub-type) in the general population of small-sized polygons in and around the AIB. On Earth, low-centred polygons are a commonplace characteristic of periglacial landscapes in regions such as the Tuktoyaktuk Coastlands (TC) of northern Canada where small-sized polygons form by thermal-contraction cracking and ice wedges underlie the marginal cracks or troughs that comprise the polygon boundaries. In the TC, the accumulation (or aggradation) of ice wedges is the product of the (seasonal) migration of snow-melt into polygon cracks and the subsequent freezing of this melt-water in situ. If and when the ice wedges degrade (thaw) then the troughs overlying them lose elevation relative to the polygon centres; this gives the polygons a low-centred appearance. Although mineral-filled troughs may show a similar range of elevation-related morphologies, i.e. sand-wedge polygons in the Antarctic Dry Valleys, they are not associated spatially with landforms, i.e. debris flows (current or relict), that are geological markers of a landscape modified by "wet" processes. We suggest that the low-centred polygons observed by us are part of a landform triumvirate that when bundled together is more consistent with stable liquid-water during the Late Amazonian epoch in and around the AIB than has been thought possible hitherto.
13060873 Christenson, H. (University of Canterbury, Waterways Centre for Freshwater Management, Christchurch, New Zealand); Webster-Brown, J.; Hawes, I. and Jungblut, A. Phosphorous geochemistry in coastal meltwater ponds in McMurdo Sound, Antarctica [abstr.]: in Geosciences 2012; annual conference of the Geoscience Society of New Zealand; abstracts (Pittari, Adrian, editor; et al.), Geoscience Society of New Zealand Miscellaneous Publication, 134A, p. 15-16, 2012. Meeting: Geosciences 2012; annual conference of the Geoscience Society of New Zealand, Nov. 25-28, 2012, Hamilton, New Zealand. Accessed on July 17, 2013.
URL: https://securepages.net.nz/~gsnz/siteadmin/uploaded/gs_downloads/Abstracts/2012H ...
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