August 2013 Permafrost Alert
The U.S. Permafrost Association, together with the American Geosciences Institute (AGI), is pleased to provide the following Permafrost Monthly Alerts (PMA). The AGI GeoRef service regularly scans the contents of over 3500 journals in 40 languages from the global geosciences literature, comprised of approximately 345 different sources. In addition to journals, special publications such as papers in proceedings and hard-to-find publications are provided. Each PMA represents a listing of the permafrost-related materials added to GeoRef during the previous month. Where available, a direct link to the publication is included, which provides access to the full document if you or your institution have a current online subscription.
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13072413 Burn, Christopher R., editor (Carleton University, Ottawa, ON, Canada). Transactions of the International Permafrost Association: Permafrost and Periglacial Processes, 24(2), p. 96-155, illus., June 2013. Individual papers within scope are cited separately.
13072414 Etzelmuller, Bernd (University of Oslo, Dpeartment of Geosciences, Oslo, Norway). Recent advances in mountain permafrost research: in Transactions of the International Permafrost Association (Burn, Christopher R., editor), Permafrost and Periglacial Processes, 24(2), p. 99-107, illus. incl. sketch maps, 85 ref., June 2013.
Knowledge of the thermal state of mountain permafrost has greatly increased since 2007 with the establishment of numerous new monitoring stations around the world. Data collected at these sites have pointed to longer-term changes in ground temperatures, which seem to have increased during the last two to three decades in cold permafrost, while in ground close to 0°C the near-surface ice content has restricted warming and similar trends are not apparent. Modelling of mountain permafrost has developed greatly, driven by general circulation models or gridded temperature maps, through both predictive methods and spatial equilibrium and transient approaches. The spatial resolution of climate parameters, which is normally much coarser than the spatial heterogeneity of alpine environments, presents a major problem for modelling studies. This is a fundamental challenge for future research. Abstract Copyright (2010), John Wiley & Sons, Ltd.
13072417 Hauck, Christian (University of Fribourg, Department of Geosciences, Fribourg, Switzerland). New concepts in geophysical surveying and data interpretation for permafrost terrain: in Transactions of the International Permafrost Association (Burn, Christopher R., editor), Permafrost and Periglacial Processes, 24(2), p. 131-137, illus., 44 ref., June 2013.
This review focuses on advances in applications of geophysical methods to permafrost terrain that have emerged in 2007-12. Improvements in the four main geophysical techniques presently used in permafrost research (i.e. electric, electromagnetic, seismic and radar methods) and new or resurrected methods for permafrost applications are discussed. Advances in geophysical monitoring and quantitative interpretation of geophysical survey results are presented, especially for ground ice and water content. Electrical resistivity is now used operationally for long-term monitoring of ice content, as well as for short-term process studies. Quantitative approaches to determine realistic ice and liquid water content values and their spatial and temporal variability exist, but need to be further refined to be widely applicable for geotechnical and numerical modelling purposes. Abstract Copyright (2010), John Wiley & Sons, Ltd.
13072419 Kuhry, P. (Stockholm University, Department of Physical Geography and Quarternary Geology, Stockholm, Sweden); Grosse, G.; Harden, J. W.; Hugelius, G.; Koven, C. D.; Ping, C. L.; Schirrmeister, L. and Tarnocai, C. Characterisation of the permafrost carbon pool: in Transactions of the International Permafrost Association (Burn, Christopher R., editor), Permafrost and Periglacial Processes, 24(2), p. 146-155, illus. incl. 1 table, sketch map, 54 ref., June 2013.
The current estimate of the soil organic carbon (SOC) pool in the northern permafrost region of 1672 Petagrams (Pg) C is much larger than previously reported and needs to be incorporated in global soil carbon (C) inventories. The Northern Circumpolar Soil Carbon Database (NCSCD), extended to include the range 0-300 cm, is now available online for wider use by the scientific community. An important future aim is to provide quantitative uncertainty ranges for C pool estimates. Recent studies have greatly improved understanding of the regional patterns, landscape distribution and vertical (soil horizon) partitioning of the permafrost C pool in the upper 3 m of soils. However, the deeper C pools in unconsolidated Quaternary deposits need to be better constrained. A general lability classification of the permafrost C pool should be developed to address potential C release upon thaw. The permafrost C pool and its dynamics are beginning to be incorporated into Earth System models, although key periglacial processes such as thermokarst still need to be properly represented to obtain a better quantification of the full permafrost C feedback on global climate change. Abstract Copyright (2010), John Wiley & Sons, Ltd.
13072418 Lacelle, Denis (University of Ottawa, Department of Geography, Ottawa, ON, Canada) and Vasil'chuk, Yurij K. Recent progress (2007-2012) in permafrost isotope geochemistry: in Transactions of the International Permafrost Association (Burn, Christopher R., editor), Permafrost and Periglacial Processes, 24(2), p. 138-145, illus., 52 ref., June 2013.
This paper reviews contributions to permafrost isotope geochemistry published between 2007 and 2012 and proposes future research directions. It focuses on: (1) the origin and age of ground ice; (2) geochemistry and water movement in the active and transient layers; and (3) geochemistry and water movement in deep permafrost. The use of isotope geochemistry to study permafrost-related processes has grown significantly over the last few years. These processes have been elucidated by combining geochemical and isotope measurements from different components of permafrost. Such combination has yielded new insights, for example, into the water source and transfer processes that lead to the formation of ground ice, as well as groundwater movement and residence time in permafrost. Permafrost isotope geochemistry has a promising future and should provide valuable tools for the study of a rapidly changing permafrost environment. Abstract Copyright (2010), John Wiley & Sons, Ltd.
13072416 Lantuit, H. (Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany); Overduin, P. P. and Wetterich, S. Recent progress regarding permafrost coasts: in Transactions of the International Permafrost Association (Burn, Christopher R., editor), Permafrost and Periglacial Processes, 24(2), p. 120-130, illus. incl. 2 tables, June 2013.
Permafrost coasts make up to 34 per cent of the world's coastlines. Erosion of these coasts currently averages 0.5 m a-1, which is similar to or greater than rates observed in temperate regions. The erosion rate has risen on the Arctic coast of Alaska during the first decade of the 21st century as the minimum sea ice extent has declined. Increasing erosion leads to higher engineering and relocation costs for coastal villages (US$140 million for Kivalina alone to adapt and eventually relocate), and to greater quantities of organic carbon contained in permafrost being released to the near-shore zone (up to 46.5 Tg a-1). Modelling of coastal erosion has begun to include permafrost-specific components such as block failure. The absence of basic information on Arctic coasts that would be provided by a dedicated observing network, especially on lithified coasts, has hindered the development of a system model with predictive capability. Abstract Copyright (2010), John Wiley & Sons, Ltd.
13070412 Jepsen, S. M. (U. S. Geological Survey, Denver, CO); Voss, C. I.; Walvoord, M. A.; Minsley, B. J. and Rover, J. Linkages between lake shrinkage/expansion and sublacustrine permafrost distribution determined from remote sensing of interior Alaska, USA: Geophysical Research Letters, 40(5), p. 882-887, illus. incl. sketch maps, 32 ref., March 16, 2013.
Linkages between permafrost distribution and lake surface-area changes in cold regions have not been previously examined over a large scale because of the paucity of subsurface permafrost information. Here, a first large-scale examination of these linkages is made over a 5150 km2 area of Yukon Flats, Alaska, USA, by evaluating the relationship between lake surface-area changes during 1979-2009, derived from Landsat satellite data, and sublacustrine groundwater flow-path connectivity inferred from a pioneering, airborne geophysical survey of permafrost. The results suggest that the shallow (few tens of meters) thaw state of permafrost has more influence than deeper permafrost conditions on the evolving water budgets of lakes on a multidecadal time scale. In the region studied, these key shallow aquifers have high hydraulic conductivity and great spatial variability in thaw state, making groundwater flow and associated lake level evolution particularly sensitive to climate change owing to the close proximity of these aquifers to the atmosphere. Abstract Copyright (2013), American Geophysical Union. All Rights Reserved.
13072415 Kokelj, S. V. (Northwest Territories Geoscience Office, Yellowknife, NT, Canada) and Jorgenson, M. T. Advances in thermokarst research: in Transactions of the International Permafrost Association (Burn, Christopher R., editor), Permafrost and Periglacial Processes, 24(2), p. 108-119, illus., 120 ref., June 2013.
The term thermokarst describes the processes and landforms that involve collapse of the land surface as a result of the melting of ground ice. We review the literature that has contributed to our understanding of patterns, processes and feedbacks, and the environmental consequences of thermokarst, focusing on hillslope, thaw lake and wetland processes. Advances in remote sensing techniques, and their application in a broad suite of change detection studies, indicate recent increases in the rates and magnitude of thermokarst including retrogressive thaw slumping, lake expansion and the transformation of frozen peatlands to collapsed wetlands. Field-based studies and modelling have enhanced the knowledge of processes and feedbacks associated with warming permafrost, changes in talik geometry and accelerated thaw slump activity, and thaw lake expansion. Hydrological processes can strongly influence the rates of thaw lake and gully development, and the degradation of frozen peatlands. Field studies and calibrated modelling efforts that investigate the drivers of thermokarst and test conceptual ideas of landscape evolution will be critical to further advance the prediction of landscape and ecosystem change. Thermokarst research provides an important context for studying the environmental implications of permafrost degradation. Hillslope thermokarst can alter the water quality of lakes and streams with implications for aquatic ecosystems. Investigation of the interactions between thermokarst and hydrologic and ecological processes has improved knowledge of the feedbacks that accelerate change or lead to stabilisation in terrestrial and thaw lake environments. Finally, the influence of permafrost thaw on soil carbon dynamics will be an important focus of thermokarst research because of feedbacks with the global climate system. Abstract Copyright Her Majesty the Queen in Right of Canada 2013.
13069104 Watson, Vanessa (Vrije University Amsterdam, Department of Earth Sciences, Amsterdam, Netherlands); Kooi, Henk and Bense, Victor. Potential controls on cold season river flow behavior in subarctic river basins of Siberia: Journal of Hydrology, 489, p. 214-226, illus. incl. 3 tables, sketch maps, 75 ref., May 10, 2013. Includes appendices.
Results are presented of an inter-basin comparison of cold-season (October-April/March) river flow characteristics for 17 undisturbed catchments in Siberia for the period 1980-1998. Flow and recession metrics for each basin and mean annual cold-season catchment-averaged drainage depth, Qcold (mm), were analyzed with various basin attributes in an attempt to detect potential controls of recession behavior. There is a marked behavioral distinction between basins on non-continuous (n=6) permafrost coverage (discontinuous/sporadic/isolated) and those on continuous (n=11) permafrost. The first group is characterized by slow recession, relatively high discharge in April before spring freshet, and high values for Qcold up to about 80 mm, which corresponds to more than 10% of total annual rainfall. Although positive correlations with several catchment attributes (annual precipitation regime; peat land fraction) are found, higher abundance of through-taliks and greater active layer depth (ALD) are presumed to be the most likely controls of the distinctive hydrological behavior of catchments containing non-continuous permafrost. Within the group of catchments on continuous permafrost, characteristics of cold-season flow vary conspicuously as some rivers exhibit very fast recession and cessation of flow for 3-4 months, while others show strongly reduced, but continuous discharge throughout the cold season. Our analysis shows that lake area fraction, peatland fraction and morphological metrics may play a role in favoring prolonged cold-season flow in this group. Whether prolonged cold-season flow in areas of continuous permafrost also signals contributions to river flow from intra- and/or sub-permafrost groundwater remains an intriguing but so far unresolved question. Abstract Copyright (2013) Elsevier, B.V.
13070212 Matell, N. (University of Colorado at Boulder, Institute of Arctic and Alpine Research, Boulder, CO); Anderson, R. S.; Overeem, Irina; Wobus, C.; Urban, F. E. and Clow, G. D. Modeling the subsurface thermal impact of Arctic thaw lakes in a warming climate: in Modeling for environmental change (Kettner, Albert J., editor; et al.), Computers & Geosciences, 53, p. 69-79, illus. incl. 2 tables, sketch map, 60 ref., April 2013. Includes appendices.
Warming air temperatures in the Arctic are modifying the rates of thermokarst processes along Alaska's Arctic Coastal Plain. The Arctic Coastal Plain is dominated by thaw lakes. These kilometer-scale lakes are the most visible surface features in the region, and they provide important habitats for migratory birds. The lakes are formed by thermokarst processes, and are therefore susceptible to change as warming continues. We present a 1D numerical model of permafrost and subsidence processes in order to investigate the subsurface thermal impact of thaw lakes of various depths, and to evaluate how this impact might change in a warming climate. Currently, most thaw lakes in the region are shallow (<~2 m deep), freeze to their base each winter, and are not underlain by permanently unfrozen ground (taliks). Field observations indicate that these shallow lakes have not greatly altered the thermal structure of the subsurface. Our model suggests that under a warming scenario, the number of lakes that do not freeze to their base during the winter, and are therefore underlain by taliks, will increase. Such changes could substantially alter the hydrology of the Arctic Coastal Plain. Abstract Copyright (2013) Elsevier, B.V.
13070357 Parsekian, Andrew D. (Stanford University, Department of Geophysics, Stanford, CA); Grosse, Guido; Walbrecker, Jan O.; Müller-Petke, Mike; Keating, Kristina; Liu, Lin; Jones, Benjamin M. and Knight, Rosemary. Detecting unfrozen sediments below thermokarst lakes with surface nuclear magnetic resonance: Geophysical Research Letters, 40(3), p. 535-540, illus., 25 ref., February 16, 2013.
A talik is a layer or body of unfrozen ground that occurs in permafrost due to an anomaly in thermal, hydrological, or hydrochemical conditions. Information about talik geometry is important for understanding regional surface water and groundwater interactions as well as sublacustrine methane production in thermokarst lakes. Due to the direct measurement of unfrozen water content, surface nuclear magnetic resonance (NMR) is a promising geophysical method for noninvasively estimating talik dimensions. We made surface NMR measurements on thermokarst lakes and terrestrial permafrost near Fairbanks, Alaska, and confirmed our results using limited direct measurements. At an 8 m deep lake, we observed thaw bulb at least 22 m below the surface; at a 1.4 m deep lake, we detected a talik extending between 5 and 6 m below the surface. Our study demonstrates the value that surface NMR may have in the cryosphere for studies of thermokarst lake hydrology and their related role in the carbon cycle. Abstract Copyright (2013), American Geophysical Union. All Rights Reserved.
13071119 Bryukhan', F. F. (Moskovskiy Gosudarstvennyy Stroitel'nyy Universitet, Moscow, Russian Federation) and Lebedev, V. V. Ekologo-geokhimicheskoye sostoyaniye territorii zolotoserebryanogo mestorozhdeniya "Klen" (Chukotskiy avtonomnyy okrug) [Ecologo-geochemical conditions of the Klen gold-silver deposit region (Chukchi)]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 10-20 (English sum.), 4 tables, sketch maps, 20 ref., December 2012.
According to the results of field works of sampling of soil, ground, and bottom sediments of surface waters in the Klen and Alisa Creeks and vegetation (larch pine needles) samples in the territory of the Klen Mine (Bilibino region of Chukot Autonomous Okrug) and further laboratory examinations, ecological and geochemical estimation of landscape component pollution have been performed. It has been revealed that the soil ground layer is characterized by an acid or weak-acid reaction or, rarely, neutral reaction. The metal concentrations in the bottom sediments of creeks exceed considerably the corresponding concentrations in the soils and in the ground. The highest concentrations of microelements of soil and ground are typical of the man-induced sites of the minefield. Surface waters of the Klen and Alisa Creeks are of hydrocarbonate, mostly magnesium-sodium-calcium chemical composition, with a weak-acid reaction, very soft, sweet and fresh. It is shown that the microelement accumulation level in the pine needles may serve as the indicator of the ecological condition of the territory. Generally, the ecological and geochemical state of landscape components of the investigated territory is satisfactory. It is marked that the permafrost essentially determines the ecological and geochemical state of the territory and its change during the construction and maintenance of the deposit.
13071125 Demidov, N. E. (Russian Academy of Sciences, Institute for Physicochemical and Biological Problems of Soil, Pushchino, Russian Federation); Gilichinskiy, D. A.; Mironov, V. A. and Shmakova, L. A. Kriobiosfera Zemli i poisk zhizni na Marse [Earth's cryobiosphere and search for life on Mars]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 67-82 (English sum.), table, 146 ref., December 2012.
At the early Noachian time (4.6-3.7 billion years ago) Mars was evolving in a scenario similar to Earth that could imply the appearance of life on early Mars. In Hesperian and Amazonian time the global freezing place on Mars. In the post-Noachian time geothermal oases could be formed on the frozen surface. Those oases could be related to tectonic and volcanic activity and located in ground water effusion areas. Underground microorganisms could be transported to the surface in such locations. It is hard to extrapolate the experience of terrestrial cryobiosphere explorations to Martian analogs because of the great difference in the age of permafrost. Furthermore, most of Martian permafrost was formed without any connection with ground water and in lifeless conditions. The most promising location for the search for life could be permanently frozen sediments of the Polar Volcanic Province. This region includes several young cinder cones and shield-volcanoes at the edge of the polar ice cap. There are several terrestrial analogs of Martian Polar Volcanic Province such as permanently frozen volcanic sediments at Kamchatka Peninsula and Antarctic volcanoes. Thermophillic microorganisms have been isolated from the permafrost in both locations. It is necessary to perform shallow drilling (2-3 m) in Polar Volcanic Province on Mars for searching for signs of life. It is possible to realize this project by interplanetary automatic stations even nowadays.
13071118 Mel'nikov, V. P. (Russian Academy of Sciences, Siberian Division, Institute of the Cryosphere, Tyumen, Russian Federation). Noveyshiye yavleniya, kontseptsii, instrumentariy kak fundament dlya starta k novym gorizontam kriologii [New concepts, techniques and instruments applied to cryosphere studies]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 3-9 (English sum.), illus., 15 ref., December 2012.
The increasingly growing research in physics and chemistry of cryogenic phenomena has extended the bounds of understanding the role of ice, snow, and ice-like structures in the solar system. In this paper, some prospects in cryology are outlined proceeding from the gained systematic knowledge of the cold world. This knowledge is due to recent advances in modeling molecular interaction in water, ice, and gas hydrates, as well as to new models of gas hydrates implying their long existence in metastable states at negative temperatures. It is necessary to continue studying the effects of drop clusters on cold upper atmosphere and the possibilities for using "dry water" in new technologies of gas transportation and storage. As an extension of ideas by Vladimir Vernadskiy on links between life and different spheres of Earth (atmosphere, hydrosphere, cryosphere), new avenues are also opening in the research on viable paleobiota isolated from permafrost to improve the extant biological systems.
13071123 Sycheva, S. A. (Russian Academy of Sciences, Institute of Geography, Moscow, Russian Federation). Paleomerzlotnyye sobytiya v periglyatsial'noy oblasti Srednerusskoy vozvyshennosti v kontse srednego i pozdnem pleystotsene [Paleocryogenic events in periglacial area of the Central Russian Upland during the middle and late Pleistocene]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 45-56 (English sum.), illus. incl. table, sketch map, 24 ref., December 2012.
This article is devoted to the results of the study of the morphology, stratigraphic position and genesis of the cryogenic phenomena at the end of the middle and late Pleistocene in a periglacial zone of the Russian Platform. The features related to the continuous and discontinuous permafrost and deep seasonal freezing are described, and the relationships between the paleocryogenic features and paleosols are demonstrated. Seven cryogenic horizons have been identified: Moscow, Seim, Mlodat, Selihovodvor, Tuskar, Vladimir, and Yaroslavl. They are of stratigraphic importance and reflect the coldest phase of the climatic rhythms of the middle and late Pleistocene.
13074166 Andreyev, V. I. (Russian Academy of Sciences, Far Eastern Division, Institute of Volcanology and Seismology, Petropavlovsk-Kamchatskiy, Russian Federation) and Nikolayeva, A. G. Geoekologicheskiye posledstviya izverzheniy vulkana Karymskiy i kratera Tokareva (Vostochnaya Kamchatka) po dannym nablyudeniy za 1996-2008 gg. [Environmental effects of Karymskiy and Tokareva volcanic eruptions (eastern Kamchatka) according to observations in 1996-2008]: Vulkanologiya i Seysmologiya, 2012(6), p. 3-17 (English sum.), illus. incl. 3 tables, sketch maps, 26 ref., December 2012.
This paper considers the geoecological impacts of eruptions on Karymskiy Volcano and the Tokareva Crater for the 1996-2008 period, which resulted in changes in: (a) the relief around these edifices, (b) the discharge and compositions of water in the Karymskiy River and other streams in the area, and (c) the discharge and composition of gases in thermal springs. It was found that the concentration of CH4 previously had been abnormally high in free gases that emanated from the new P1ripovskiy springs and an explanation is provided for the decrease in their concentration over time. Variations in the radon activity, OARn (Bq/m3), in free gases that are released in the Karymskiy Caldera hydrothermal occurrence were detected. The variations are consistent with those in the eruptive activity of Karymskiy Volcano in 2005-2006. Permafrost rocks in the Karymskiy Caldera that favor the generation of a cryolithic zone are described.
13074041 Kodama, J. (Hokkaido University, Graduate School of Engineering, Sapporo, Japan); Goto, T.; Fujii, Y. and Hagan, P. The effects of water content, temperature and loading rate on strength and failure process of frozen rocks: International Journal of Rock Mechanics and Mining Sciences (1997), 62, p. 1-13, illus. incl. 2 tables, 33 ref., September 2013.
The effects of water content, temperature and loading rate on the strength and failure process of rock at sub-zero temperatures were investigated and are presented in this paper. Over the range of temperatures studied there was little change observed in the properties of dry rock. The presence of water in the rock, however, resulted in a marked increase in rock strength and the fracture initiation stress. Rock strength increased with amount of water present and the rate of load application, with the effect being exacerbated at the colder temperatures. Interestingly, the changes in strength were not uniform as there was a greater rate of increase in the tensile strength of rock with temperature than compressive strength. It is postulated that these changes in mechanical properties may be explained in part by a reduction in the stress concentration within the interstitial spaces and cracks of the rock samples tested. Abstract Copyright (2013) Elsevier, B.V.
13071121 Garagulya, L. S. (Moscow State University, Moscow, Russian Federation); Gordeyeva, G. I. and Ospennikov, Ye. N. Rol' geokriologicheskikh protsessov v formirovanii i dinamike ekosistem kriolitozony [Role of geocryologic processes in the formation and dynamics of cryolithozone ecosystems]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 31-41 (English sum.), illus. incl. 2 tables, 22 ref., December 2012.
This article highlights the problems of forming and dynamic development of ecosystems in the cryolithic zone under the influence of geocryological processes. It is demonstrated that under certain conditions the development of both processes and landscapes is of a cyclic nature. By the example of different regions the specific complexes of geocryological processes are observed and the forecast estimate of their development is given. The anthropogenic dynamics of geocryological processes is studied as well.
13071120 Ponomareva, O. E. (Russian Academy of Sciences, Siberian Division, Institute of the Cryosphere, Tyumen, Russian Federation); Gravis, A. G. and Berdnikov, N. M. Sovremennaya dinamika bugrov pucheniya i ploskobugristykh torfyanikov v severnoy tayge Zapadnoy Sibiri (na primere Nadymskogo statsionara) [Modern dynamics of frost-heave mounds and peatlands in the northern taiga zone of West Siberia (example from the Nadym area)]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 21-30 (English sum.), illus. incl. sketch map, 25 ref., December 2012.
It has been proved that, despite climate warming since the 1970s, frost heave has still been an active process in the northern taiga of West Siberia. It has been established that the frost heave here involved not only the uneven-age (including the relict ones) frost mounds and the bogs, but also the flat peatland. Features of manifestation of the frost heave in space and the interrelation between the intensity of the frost heave and the climatic parameters have been discussed. The reduction of the frost heave intensity and the thermokarst revival observed during the last 10 years due to the proceeding drowning of climate in the XXI century has been reasoned. During some favorable years with low-snow winters insignificant revival of the frost heave process and a slight surface lifting have been marked. That is why the surfaces of hillocks and peatlands have been generally kept on the marks of 10-year prescription. Thus, all the created forms of frost heave and peatlands in the northern taiga of West Siberia have been in the condition of unstable balance. At the same time the active growth of new hillocks and small ridges of frost heave in the regional parts of bogs has been revealed.
13071122 Vtyurin, B. I. (Russian Academy of Sciences, Far Eastern Division, Pacific Institute of Geography, Vladivostok, Russian Federation) and Govorushko, S. M. "Prichudy" termokarsta ["Fancy" thermokarst]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 42-44 (English sum.), illus., 11 ref., December 2012.
Thermokarst processes in the low reaches of the Indigirka River are considered. Vorontsov Yar exposure--the key section for the given territory--is briefly characterized. The phenomenon of vertical and inclined arrangement of dead trees with roots up is described. The mechanism of such radical reorientation of the trees is interpreted.
13075827 Pereira, Thiago Torres C. (Universidade do Estado de Minas Gerais, Frutal, Brazil); Schaefer, Carlos Ernesto G. R.; Ker, Joao C.; Almeida, Cecilia C.; Almeida, Ivan C. C. and Batista Pereira, Antonio. Genesis, mineralogy and ecological significance of ornithogenic soils from a semi-desert polar landscape at Hope Bay, Antarctic Peninsula: Geoderma, 209-210, p. 98-109, illus. incl. 7 tables, sketch map, 46 ref., November 2013.
Large amounts of organic matter of marine origin are seasonally deposited on ice-free soils by birds and mammals, especially penguins, in some restricted Antarctic terrestrial ecosystems. The incorporation of this material into the mineral soil matrix becomes the main pathway for the widespread formation of phosphate minerals and ornithogenic soils, enhancing local biodiversity and complexity. These soils have been well-studied in Maritime Antarctica, and comparatively neglected in the cold, dry polar Antarctica. Hence, we studied the influence of penguins on soil and landscape formation at Hope Bay, a transition climatic zone in Antarctic Peninsula, where no previous pedological study has been undertaken with regards to soil phosphatization. Ten pedons, nine of which are ornithogenic, were described, sampled, and analyzed for physical, chemical and mineralogical properties. Results indicate that the slow mineralization of bird guano, coupled with high levels of organic matter and reduced leaching, notably Ca, contribute to reduced soil acidification and low exchangeable Al3+ content, unlike ornithogenic soils from Maritime Antarctica. Phosphate minerals typical of the phosphatization process, such as taranakite, minyulite, leucophosphite, struvite, and fluorapatite, were detected. In Hope Bay, they are subjected to very slow rates of dissolution, neoformation of secondary phosphatic minerals, and mineralogical transformation and leaching processes. Ornithogenesis is viewed as a mechanism of sea-land nutrient transfer, enriching the latter, since the parent rocks are chemically poor sedimentary materials. On the other hand, the presence of kaolinite indicates wetter climate conditions in the past, with periods with greater moisture and weathering, compared with the current semi-polar desert environment. We conclude that the phosphatization process overprints previously weathered sedimentary materials. Abstract Copyright (2013) Elsevier, B.V.
13073811 Young, Grant M. (Western University, Department of Earth Sciences, London, ON, Canada). Secular changes at the Earth's surface; evidence from palaeosols, some sedimentary rocks, and palaeoclimatic perturbations of the Proterozoic Eon: in Secular changes in geologic and tectonic processes (Kusky, T. M., editor; et al.), Gondwana Research, 24(2), p. 453-467, illus. incl. geol. sketch map, 140 ref., September 2013.
Secular changes in surficial processes and products are closely linked to plate tectonics, atmospheric composition, solar evolution and climate. Most siliciclastic sediments and rocks are derived from weathering profiles rather than directly from older rocks. Many palaeosols older than ~2.2 Ga show depletion in Fe(T), whereas in younger palaeosols, and modern soils, Fe is virtually immobile. This is thought to reflect the accumulation of free oxygen in the Earth's atmosphere, as is the 'disappearance' of iron formations after about 1.8 Ga. The temporal distribution of mature siliciclastic sedimentary rocks containing detrital pyrite and uraninite, and the subsequent appearance of fluvial and shallow marine red beds provide compelling evidence for oxygenation in early Palaeoproterozoic times. During periods of supercontinentality, especially at low palaeolatitudes, enhanced weathering of exposed rock surfaces led to production of thick, extensive quartzarenites, some of which are associated with glaciogenic rocks. Intense weathering during periods of supercontinentality would have decreased atmospheric CO2, leading to extensive glaciations near the beginning and end of the Proterozoic Eon, and initiating a feedback loop that resulted in strong climatic oscillations until continental break-up brought stability to the climatic regime. It has been proposed that atmospheric oxygenation took place during warm climatic episodes between these glaciations when abundant nutrients were flushed into the oceans, stimulating unprecedented cyanobacterial blooms. Although many other supercontinents have been proposed, these unusual climatic conditions probably reflect rare critical relationships among solar luminosity, atmospheric composition and palaeolatitudinal distribution of continental lithosphere. Reappearance of iron formations associated with some Neoproterozoic glaciations may be explained by hydrothermal activity in semi-isolated rift basins. Abstract Copyright (2013) Elsevier, B.V.
13073799 Brocca, L. (National Research Council, Research Institute for Geo-Hydrological Protection, Perugia, Italy); Tarpanelli, A.; Moramarco, T.; Melone, F.; Ratto, S. M.; Cauduro, M.; Ferraris, S.; Berni, N.; Ponziani, F.; Wagner, W. and Melzer, T. Soil moisture estimation in alpine catchments through modeling and satellite observations: in Remote sensing for vadose zone hydrology (Mohanty, Binayak P., editor; et al.), Vadose Zone Journal, 12(3), 10 p., illus. incl. 3 tables, 64 ref., August 2013.
Soil moisture is widely recognized as a state variable governing the mass and energy balance between the land surface and the atmosphere. For that, its knowledge is of upmost importance for many applications including flood and landslide prediction. In alpine catchments, soil moisture estimation is a very difficult task, because of complex topography, high vegetation density, and presence of snow and outcrops. In this study, the possibility to estimate soil moisture for these areas by using modeled and satellite data is investigated. Specifically, an updated version of a soil water balance model, which takes the snowmelt process into account, is employed. Moreover, satellite-derived soil moisture observations obtained by the Advanced SCATterometer (ASCAT) sensor onboard the MetOp satellite are tested by considering two products: the Surface Soil Moisture (SSM) and the Soil Water Index (SWI). The latter is obtained through the application of an exponential filter and it is aimed to reduce the differences in the layer depth of in situ measurements (10 cm) and satellite data (~2-3 cm). Quality-checked in situ soil moisture measurements collected at four continuous monitoring sites in Valle d"Aosta (North Italy) are used to test the accuracy of modeled and satellite estimates. Notwithstanding the above issues, results indicated the potential not only of modeling approaches but also, unexpectedly, of satellite data to retrieve soil moisture in high elevation regions (>1000 m a.s.l.). Indeed, by estimating correctly the snowmelt contribution, the agreement between modeled and observed data is quite good, with correlation coefficient values, r, in the range 0.795-0.940. In addition, the ASCAT-derived SWI product provides satisfactorily results with r = 0.635-0.869. Based on these findings, in situ, modeled, and satellite soil moisture data will be used for improving flood and landslide risk prediction at the Valle d'Aosta Functional center to improve the Civil Protection Alert System.
13072623 Neubauer, E. (University of Vienna, Department of Environmental Geosciences, Vienna, Austria); von der Kammer, F.; Knorr, K. H.; Peiffer, S.; Reichert, M. and Hofmann, T. Colloid-associated export of arsenic in stream water during stormflow events: Chemical Geology, 352, p. 81-91, illus. incl. 3 tables, 77 ref., August 16, 2013. Includes appendices.
Significant correlations between arsenic concentrations and those of iron and natural organic matter (NOM) have been found in run-off from wetlands. This has been suggested to be a result of mobilization of arsenic-NOM colloids. The aim of this study was therefore to elucidate the possible association of iron and arsenic with colloids in surface water from a small, forested catchment area. The impacts that groundwater levels prior to stormflow events and the chemistry of the hydraulically active soil layers have on the release and formation of colloids, such as NOM and iron (oxy)hydroxide colloids, were also investigated. At baseflow, the NOM, iron, and arsenic concentrations in the stream water were relatively low (<650 mmol·L-1, <5.5 mmol·L-1, and 8-16 nmol·L-1, respectively), and the pH was close to deep groundwater (4.6-5.5). At low groundwater levels prior to stormflow events, the discharging stream water was fed by anoxic groundwater from the deeper layers of the peat, and by deep, oxic groundwater. The iron/DOC ratio in the stream water was high, and iron was present as iron-NOM colloids and precipitated as iron (oxy)hydroxide colloids. Arsenic was dissolved and associated with NOM, and the conditional distribution coefficients of arsenic binding to NOM (logKD values) were relatively high (around 3 L·mol-1). When initial groundwater table levels were high before stormflow events, the stream was fed by shallow peat layers rich in NOM, iron, and arsenic during the event. The iron/DOC ratios were low and most of the iron was present in iron-NOM colloids in the stream water. The pH of the stream water was also lower under these conditions, and the logKD values of As-NOM associations in the stream water were accordingly lower (<3 L·mol-1). Large quantities of dissolved arsenic (<1000 g·mol-1) were exported under these conditions. Our data reveal that the logKD values of As-NOM associations decreased with increasing discharge as a consequence of decreasing pH. The logKD values for arsenic-NOM associations in this study are higher than those reported elsewhere in published literature, which had been derived from laboratory tests with NOM and arsenic. The formation of ternary complexes with ferric iron may therefore have enhanced the binding of arsenic to NOM within the studied stream. Abstract Copyright (2013) Elsevier, B.V.
13073801 te Brake, Bram (Wageningen University, Soil Physics and Land Management Group, Wageningen, Netherlands); Hanssen, Ramon F.; van der Ploeg, Martine J. and de Rooij, Gerrit H. Satellite-based radar interferometry to estimate large-scale soil water depletion from clay shrinkage; possibilities and limitations: in Remote sensing for vadose zone hydrology (Mohanty, Binayak P., editor; et al.), Vadose Zone Journal, 12(3), 13 p., illus. incl. sketch maps, 70 ref., August 2013.
Satellite-based radar interferometry is a technique capable of measuring small surface elevation changes at large scales and with a high resolution. In vadose zone hydrology, it has been recognized for a long time that surface elevation changes due to swell and shrinkage of clayey soils can serve as an estimate for soil water storage change. Therefore, satellite-based radar interferometry can potentially offer an alternative methodology to estimate soil water storage change at field or regional scales. This paper introduces principles of satellite-based radar interferometry and identifies limitations and potential applications of the technique to measure surface elevation changes from clay shrinkage. In situ measurements were performed and a linear relation between soil water storage depletion and layer shrinkage was obtained. Data from the TerraSAR-X satellite over the measurement area were analyzed to identify the most favorable conditions for radar interferometry to measure vertical shrinkage. High-quality phase observations over clayey areas in polders with limited vegetation can be explained from differences in land use and soil type. Signal noise over sparsely vegetated agricultural fields was successfully reduced by multilooking over agricultural fields at the cost of spatial resolution. Good resemblance between in situ measured shrinkage and differential phase change was found in a test period. Based on this study, we expect that radar interferometric processing of data from the future satellite mission Sentinel-1 can play a crucial role in providing much-needed observations of vadose zone processes at the field scale and beyond.
13070472 Griffiths, Michael L. (William Paterson University, Department of Environmental Science, Wayne, NJ); Drysdale, Russell N.; Gagan, Michael K.; Hellstrom, John C.; Couchoud, Isabelle; Ayliffe, Linda K.; Vonhof, Hubert B. and Hantoro, Wahyoe S. Australasian monsoon response to Dansgaard-Oeschger event 21 and teleconnections to higher latitudes: Earth and Planetary Science Letters, 369-370, p. 294-304, illus. incl. 1 table, sketch map, 55 ref., May 2013. Supplemental information/data is available in the online version of this article.
Dansgaard-Oeschger (D-O) cycles were the most prominent, abrupt climate events of the last glacial period whose impact was most strongly felt in the high latitudes of the North Atlantic region. The climate links between the North Atlantic, the Asian and American tropics, and Antarctica during these cycles are well documented. However, the potential role of the Indo-Pacific Warm Pool and Australasian monsoon system in propagating climate impacts across the hemispheres is still unclear. Here, we use tandem measurements of oxygen isotopes in calcite and fluid inclusions, as well as carbon-isotope ratios, from multiple stalagmites from Liang Luar Cave, Flores (southern Indonesia) to examine the monsoon response to D-O event number 21 (~87,000-84,000 years ago), the longest and warmest event recorded in Greenland ice cores. The record shows that there was a rapid decline in monsoon rainfall in Indonesia during D-O21 warming in Greenland and cooling in Antarctica. At around the same time, the East Asian monsoon was intensified, indicating that the intertropical convergence zone (ITCZ) shifted abruptly to the north during this event. Our record also shows that there was a 2-3°C increase in local air temperature, which would have acted to increase primary productivity and promote the generation of soil carbon for methanogenesis. Therefore, our findings indicate that ITCZ positioning in tropical Australasia-through its influence on large-scale oceanic-atmospheric circulation-played a key role in transmitting the abrupt climate signal between the hemispheres, thereby facilitating the rapid rise of atmospheric CO2 and CH4 concentrations during D-O21 that ultimately led to global warming and the demise of the MIS5b stadial. Abstract Copyright (2013) Elsevier, B.V.
13073507 Breuer, Sonja (University of Trier, Department of Geology, Trier, Germany); Kilian, Rolf; Baeza, Oscar; Lamy, Frank and Arz, Helge. Holocene denudation rates from the superhumid southernmost Chilean Patagonian Andes (53°S) deduced from lake sediment budgets: Geomorphology, 187, p. 135-152, illus. incl. 5 tables, sketch maps, 98 ref., April 1, 2013.
Holocene denudation rates and their regional variations in the superhumid and temperate climate of the southernmost Patagonian Andes are poorly surveyed. Therefore we have investigated denudation in five small lake catchments (0.11-1.62 km2) across a precipitation gradient from 600 to >9000 mm yr-1 in southernmost Chile at 53°S. Variations in denudation rates can be defined most precisely by using small catchments and short time spans (Holocene) thus can be related to variable bedrock types, vegetation cover, elevation, and climate. Minimum physical denudation rates were determined from sediment budgets based on sediment echosounder data and physical properties of sediment cores. The Holocene denudation rates vary from 0.08 mm kyr-1 in the highly elevated, bare granitic rock catchments to 9.01 mm kyr-1 in the low and vegetated catchments with a basement of sedimentary rocks. These values are comparable with those from similar areas in Norway, Sweden, and NW Iceland. The high annual precipitation in the study area has only a minor effect on denudation. Enhanced geomorphic activity during paraglacial conditions caused a faster denudation after the glacier retreat until either the clastic, glacial detritus was removed or the catchment was covered with vegetation. Chemical comparisons between basement rocks and lake sediments indicate a pronounced chemical denudation in catchments with peaty soils and low soil water pH values of 3 to 5. The Holocene surface lowering rates are on average 200 fold lower than Cenozoic surface lowering rates calculated from fission-track data for the southern Andes. This discrepancy can be explained by significantly higher erosion rates during glacial periods. Abstract Copyright (2013) Elsevier, B.V.
13068135 Borisova, I. G. (Rossiyskaya Akademiya Nauk, Dal'nevostochnoye Otdeleniye, Botanicheskiy Sad-Institut, Blagoveshchensk, Russian Federation). Prirodnyye osobennosti gornotayezhnykh landshaftov Verkhnego Priamur'ya [Natural features of mountain-taiga landscapes of the upper Amur region]: Geografiya i Prirodnyye Resursy, 2012(4), p. 126-136 (English sum.), illus. incl. 2 tables, sketch maps, 14 ref., December 2012.
A case study of the landscape complexes within the Sergachi-Khiktinskiye River basin revealed specific natural features of the mountain-taiga landscapes of the Upper Amur region. Landscape profiles and a landscape map are presented, and physico-chemical indices of soils are provided. The study of the landscape structure of the territory under investigation took into consideration the age and structure of the relief, the hydrothermal regime, the cryogenic conditions of soils and earth materials, and the character of vegetation and soil cover.
13071126 Roman, L. T. (Moskovskiy Gosudarstvennyy Universitet, Moscow, Russian Federation) and Kesariyskiy, A. G. Issledovaniye polzuchesti merzlykh gruntov i l'da metodom golograficheskiy interferometrii [Studies of creep in frozen ground and ice with the use of holographic interferometry]: Kriosfera Zemli = Earth Cryosphere, 16(4), p. 83-92 (English sum.), illus. incl. 3 tables, 19 ref., December 2012.
The possibility of experimental research of tensely-deformed condition of ice and frozen ground has been demonstrated by the method of laser interferometry. Methodical features of experiences have been revealed. The dependence of creep of frozen ground and ice on the time has been obtained on the basis of laser interferograms.
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13068675 Gruber, Stephan (University of Zurich, Department of Geography, Zurich, Switzerland); Girard, Lucas; Amitrano, David; Beutel, Jan and Weber, Samuel. Can improved understanding of frost cracking help anticipating focal zones for rockfall from degrading permafrost? [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 146, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
Rock damage due to freezing controls many phenomena on planetary surfaces. Here, we aim to investigate, how rock fall from degrading permafrost areas is preconditioned by the growth of ice-filled fractures and, whether this can be used to constrain likely locations for future rock fall better. This hypothesis of preconditioning is supported by analogies of ice-enriched transient layers in permafrost soils, by observed cryo-fracturing in soft rock and by the presence of suitable temperature gradients not only in bedrock active layers, but also insight steep alpine ridges. In order to explore the sensitivity of this phenomenon to e.g., temperature regime, moisture supply and rock type, however, corresponding simulations tools need to developed and tested against realistic conditions. To explore this scaling of theoretical insight and lab evidence to real conditions, we develop and use an outdoor sensing system to monitor acoustic emission, temperature and moisture in a steep rock face. This is done at two adjacent sites, one dry and one moist, at 3500m a.s.l. in the Swiss Alps. Our results confirm the feasibility of monitoring acoustic emissions in outdoor conditions and yield rich data and a large catalogue of acoustic events. Based on first analyses, the importance of freezing on rock damage can be demonstrated and further characterized.
13072076 Smoot, Joseph P. (U. S. Geological Survey, Reston, VA); Litwin, Ronald J.; Pavich, Milan J.; Markewich, Helaine W. and Brook, George A. Sedimentary indicators of climatic variability through the late Pleistocene in the Potomac River valley south of Washington DC [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 197, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
Unconsolidated gravel, sand, silt, and mud of late Pleistocene age forms bluffs along the tidal reaches of the Potomac River 15-30 miles south of Washington D.C.. These sediments are interpreted as an assemblage of estuarine deposits, paleosols, loess, aeolian dune deposits, ice-rafted dropstones, and thermokarst features from periods of prolonged ground ice (permafrost). Optically Stimulated Luminesence (OSL) dates from these sediments range between 90 and 30 ka. A series of cores from Hybla Valley, about 10 miles south of Washington DC, contains a similar assemblage of sediments plus carbonaceous muds suggesting marsh deposition. OSL and Accelerator Mass Spectrometry (AMS) 14C dates range from 117 to 24.5 ka, and palynological evidence suggests a nearly continuous record of climate variability from 150 to 15 ka. Estuarine deposits in the age range of 117 and 50 ka at elevations of 1-6 m above sea level require that the region was uplifted several tens of meters, probably due to a forebulge initiated during the last glacial maximum. Estuarine deposits in outcrop are comprised of upward-fining successions of gravel and sand with dune-scale cross-bedding grading up to ripple-scale cross-lamination, and common mud drapes both between cross-bedding sets and within cross-bedding. Wave-formed structures also are common. Paleosols are defined by clay-rich sediment with abundant sediment-filled root casts and narrow cracks that become less abundant downward into undisturbed sediment. The paleosols are commonly punctuated by thin beds of sand or mud indicating periods of aggradation. Thermokarst horizons are recognized by bowl-shaped pods of deformed sand and mud (pots), typically overlying muddy silts with floating pebbles and cobbles. Aeolian sands are well-sorted and well-rounded with dune-shapes on exposed surfaces recognizable in LIDAR images. In cores, warm pollen assemblages are associated with marsh deposits and carbon-rich silty muds, whereas cold conditions are associated with upward-fining wave-sorted sands or low-carbon muddy silts. Transition from cold to warm commonly exhibits soft-sediment deformation consistent with thermokarst features observed in outcrop, whereas transition from cold to warm is commonly marked by well-developed soils.
13075739 McCurdy, M. (Geological Survey of Canada, Ottawa, ON, Canada); Rainbird, R. and McNeil, R. Exploring for lead and zinc using indicator minerals with stream silt and water geochemistry in the Canadian Arctic Islands; an example from Victoria Island, Northwest Territories: in New frontiers for exploration in glaciated terrain (Paulen, R. C., editor; et al.), Open-File Report - Geological Survey of Canada, Rep. No. 7374, p. 65-70, illus., 16 ref., 2013. Meeting: New frontiers for exploration in glaciated terrain workshop, PDAC 2013 international convention, March 1, 2013, Toronto, ON, Canada. Accessed on Sept. 19, 2013.
Great Northern Mining and Exploration (GNME) carried out extensive exploration for Cu-Ni-PGE mineralization as well as diamondiferous kimberlite within the Minto Inlier between 2005 and 2008 (Montjoie and Solic, 2008). In addition to a drilling program, several hundred stream sediment samples and several thousand till and soil samples were collected for geochemical analysis and indicator mineral identification. Geophysical surveys, petrographic studies, and detailed surficial and bedrock mapping were also carried out (GNME, 2009). GNME provided the GSC with all of the information and data acquired during their exploration program on Victoria Island. A regional stream sediment and water geochemical survey, of selected areas north and east of the Minto Inlet on northwest Victoria Island (Fig. 1), was completed over two field seasons by the GSC in 2011. This activity was carried out as part of the Victoria Island Project funded under the Geo-Mapping for Energy and Minerals Program.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13075088 Cirone, Ashley M. (College of Saint Rose, Department of Physical and Biological Sciences, Albany, NY); Smith, Jacqueline A.; Johnson, Bradley G. and Diemer, John A. Sediment record from a bog on the Trujillo Meadows landslide (>10.6 ka), southeastern San Juan Mountains, southern Colorado [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 236, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
As part of our research into the extent and timing of glaciation and landsliding in the southeastern San Juan Mountains of south-central Colorado, we began an investigation of the 1.75 km2 Trujillo Meadows landslide (TML; N 37.051°, W 106.446°, ~3050-3350 m a.s.l.) in 2011. The TML is located at the southern edge of the Red Lake Plateau (~3500-3600 m a.s.l.), which is bounded by valleys glaciated during the Last Glacial Maximum, including Río de los Piños Valley. The TML occurred in the headwaters of the Rio de los Piños and formed a natural dam (now breached) across the valley at the modern spillway of the Trujillo Meadows Reservoir dam. We extracted a 3.07-m sediment core (to 4.2 m depth) from a bog located in the southern part of the TML, ~300 m from the approximate location of the toe of the landslide. The bog is elongate northwest-southeast (~100 m by ~50 m), with an area of ~2500 m2. The uppermost 3 m of the TML bog consist primarily of peaty organic material, with a transition to siltier, less organic-rich sediment between 3 and 4 m depth. The sediment corer met refusal in angular gravel at a depth of 4.18 m, indicating relatively thick deposits for a closed basin. Magnetic susceptibility (MS) was low throughout the core (-8.8-0 SI units), except in the bottom 6 cm (0.8-39.3 SI units); the highest MS reading came from the basal gravel layer. Calibrated radiocarbon dates of 10,658 ± 49, 10,596 ± 57, and 9,410 ± 65 yrs BP from macro-organics near the bottom of the core suggest that the landslide occurred no later than the early Holocene, which was reportedly a time of enhanced monsoonal activity in the region. Ongoing work on the TML includes further analysis of the core, surface-exposure dating of boulders, and analysis of soil samples from three soil pits. Recent landslides in the area, along with the continuing construction of homes in the Rio de los Piños Valley, make it important that we understand whether a landslide this large could be a modern reality or if it was simply a product of paraglacial instability during deglaciation.
13075148 Kim, Mun Gi (Seoul National University, School of Earth and Environmental Sciences, Seoul, South Korea) and Lee, Yong Il. Deglaciation history inferred from stable isotope composition of tundra vegetation at Ny-Alesund, Svalbard, Norway [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 246, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
Due to global warming, a worldwide phenomenon of glacier retreat has been occurring constantly and rapidly. As a consequence, the exposed land provides a snapshot of temporal change after deglaciation. The compositional variation of vegetation according to glacier retreat was expected to reflect soil development and primary succession. We collected vegetation samples along age gradient of exposure on a glacier foreland at Ny-Alesund, Svalbard, Norway (79°N). We grouped them into three vegetation types, vascular plants, mosses, and lichens, and assessed the carbon and nitrogen variability of the samples. Overall d13C and d15N values of collected samples ranged widely from -31.7 to -24.1ppm and from -6.3 to +9.2ppm, respectively, and a clear distinction was observed between vascular plants and lichens. They also differed in carbon and nitrogen tissue concentrations, both of which were higher in vascular plants. Mosses generally showed intermediate values. While within-group variation among vascular plants was mostly species-controlled owing to their mycorrhizal status, the composition of mosses differed for each individual. It suggests environmental factors such as soil condition, microclimate, and occasionally, animal excrements, play a greater role in mosses. The analytical data of the collected samples revealed some corresponding patterns to the deglaciation history, which in turn, may affect the ground formation process in the future. Our study site, Ny-Alesund, is a rare settlement in the Northern Hemisphere where human impact is considered minimal. It should be noted that comparison with vegetation samples taken from a pristine area 25 km distant showed that mosses and lichens around the Ny-Alesund scientific research area are significantly more enriched in nitrogen. Given that mosses and lichens are sensitive bioindicators for nitrogen deposition, the high abundance of N may imply that local N pollution by human activities had actually affected vegetation on deglaciated area near the Ny-Alesund Village. Further investigation on spatial distribution of tissue N and nitrogen isotope signature is required to verify this hypothesis.
13075159 Krueger, Kelsey (Davidson College, Department of Environmental Studies, Davidson, NC); Schmidt, Catherine; Cirone, Ashley M.; Smith, Jacqueline A.; Diemer, John A. and Johnson, Bradley G. Analysis of sediment cores from the Elk Meadows Landslide and the Silver Lakes Landslide; what sediment cores tell us about the timing and environmental conditions of large landslides in the southeastern San Juan Mountains [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 248, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
The Silver Lakes Landslide (SLL) and the Elk Meadows Landslide (EML) are located along the Alamosa and Conejos Rivers respectively in the southeastern San Juan Mountains of south-central Colorado. Silver Lakes Landslide (SLL), an estimated 6.1 km2, flows northeast down the flank of Red Mountain. Similarly, the 4.5 km2 Elk Meadows Landslide (EML) flows north off of the Red Lake Plateau. Radiocarbon dating on the nearby Trujillo Meadows Landslide (TML), suggests that landslides in the region occurred as paraglacial events after LGM deglaciation. This study aims to determine if SSL and EML occurred at roughly the same time as TML and therefore would have had similar paraglacial triggers. To test the age of the landslides, we have used a three prong approach including: 1) coring bogs formed on the surface of the landslides, 2) determining the relative age of soils on the surfaces of the landslides, and 3) using cosmogenic dating on boulders on the surface of the landslides. Here we focus on recoverable data from the cores taken from bogs on SLL and EML using a square piston rod Livingstone corer. Both bogs were relatively dry, with little to no standing water, and grass was removed from the surface to aid in coring. We recovered ~2.5 m of core on the SLL from drives extending 4.5 m below the surface while on the EML we recovered 74 cm of core from drives that extended ~3.5m below the surface. Sediments within the cores lack any sand-sized grains and are generally composed of silt with varying amounts of clay. Increasing Munsell chroma and value with depth indicate a general decrease in organic content. Nonetheless, abundant organic material throughout likely will provide C14 age control for the cores. Soil pits on SLL and EML contained large amounts of angular rocks consistent with the landslide deposit interpretation. Continuing to research these landslides is important as we further our understanding of the cause of the massive slope failures. This is especially true on SLL, where the majority of the landslide deposits are now private property containing vacation homes. Proving that the landslides were caused by the paraglacial instability of deglaciation may offer confirmation that landslides of this sort occur about as often as glaciation and are not a current threat to land owners.
13068670 Persico, Lyman P. (Mercyhurst University, Geology Department, Erie, PA); McFadden, Leslie D. and Meyer, Grant A. Episodes of increased frost shattering facilitate non-steady state accretionary soil development on hillslopes in the Sandia Mountains, New Mexico [abstr.]: in Geological Society of America, 2012 annual meeting, Abstracts with Programs - Geological Society of America, 44(7), p. 145, November 2012. Meeting: Geological Society of America, 2012 annual meeting, Nov. 4-7, 2012, Charlotte, NC.
In the Sandia Mountains foothills, differences in the weathering properties of aplite and granite produce vastly different slope deposits and forms. Granite decomposes to erodible grus, producing transient pockets of thin regolith with weak soil development and irregular slope profiles with corestones. Outcrops of aplite produce a thick regolith layer, well-developed soils, and curvilinear slopes. Aplite is less susceptible to chemical weathering than granite and serves as a local source for large, blocky clasts in downslope deposits. Aplite clast competence, clast diameter, and outcrop fracture spacing show that physical weathering is the dominant process generating blocky clasts and that weathering of aplite during downslope transport is minimal. Aplite clast-rich colluvium favors entrapment and accumulation of dust, resulting in cumulic soils with well-developed Bt and Bk horizons that reflect both the antiquity and stability of slope materials. Currently, physical weathering of aplite is minimal, but previous environmental conditions must have been favorable to this process given the large concentration of coarse aplitic clasts in the soil. Colder temperatures during glacial periods may have enhanced frost shattering of aplite. Current minimum monthly winter temperatures (-0.5 to -3.5°C) are too warm to sustain significant frost action; a minimum temperature depression of ~5°C likely is necessary to generate aplite colluviation by this process. In support, reconstructed temperatures in the Sangre de Cristo Mountains for the last glacial maximum indicate temperature depressions of 3.5-10.0°C (Leonard, 2007). Elsewhere in the Sandias, extensive quartzite exposures on steep upper slopes have produced blocky colluvium up to 5 m thick, where a silt-rich matrix also implies abundant dust trapping. Soils within these deposits contain multiple buried Bk and Bt horizons representing numerous cycles of slope stability and erosion. These features demonstrate that in the Sandia foothills, colluvial thickness and slope form are not primarily the outcome of a balance between colluvial production and downslope transport. Instead, they are the product of variable weathering and transport of materials intimately linked to antecedent environmental conditions, rock type variability, and dust input.
13074568 Van Dam, Remeke L. (Michigan State University, Department of Geological Sciences, East Lansing, MI). Landform characterization using geophysics; recent advances, applications, and emerging tools: in Geospatial technologies and geomorphological mapping (James, L. Allen, editor; et al.), Geomorphology, 137(1), p. 57-73, illus. incl. sects., sketch map, 159 ref., January 15, 2012. Meeting: 41st annual Binghamton geomorphology symposium, Oct. 15-17, 2010, Columbia, SC.
This paper presents an overview of the strengths and limitations of existing and emerging geophysical tools for landform studies. The objectives are to discuss recent technical developments and to provide a review of relevant recent literature, with a focus on propagating field methods with terrestrial applications. For various methods in this category, including ground-penetrating radar (GPR), electrical resistivity (ER), seismics, and electromagnetic (EM) induction, the technical backgrounds are introduced, followed by section on novel developments relevant to landform characterization. For several decades, GPR has been popular for characterization of the shallow subsurface and in particular sedimentary systems. Novel developments in GPR include the use of multi-offset systems to improve signal-to-noise ratios and data collection efficiency, amongst others, and the increased use of 3D data. Multi-electrode ER systems have become popular in recent years as they allow for relatively fast and detailed mapping. Novel developments include time-lapse monitoring of dynamic processes as well as the use of capacitively-coupled systems for fast, non-invasive surveys. EM induction methods are especially popular for fast mapping of spatial variation, but can also be used to obtain information on the vertical variation in subsurface electrical conductivity. In recent years several examples of the use of plane wave EM for characterization of landforms have been published. Seismic methods for landform characterization include seismic reflection and refraction techniques and the use of surface waves. A recent development is the use of passive sensing approaches. The use of multiple geophysical methods, which can benefit from the sensitivity to different subsurface parameters, is becoming more common. Strategies for coupled and joint inversion of complementary datasets will, once more widely available, benefit the geophysical study of landforms. Three cases studies are presented on the use of electrical and GPR methods for characterization of landforms in the range of meters to 100s of meters in dimension. In a study of polygonal patterned ground in the Saginaw Lowlands, Michigan, USA, electrical resistivity tomography was used to characterize differences in subsurface texture and water content associated with polygon-swale topography. Also, a sand-filled thermokarst feature was identified using electrical resistivity data. The second example is on the use of constant spread traversing (CST) for characterization of large-scale glaciotectonic deformation in the Ludington Ridge, Michigan. Multiple CST surveys parallel to an ~60 m high cliff, where broad (~100 m) synclines and narrow clay-rich anticlines are visible, illustrated that at least one of the narrow structures extended inland. A third case study discusses internal structures of an eolian dune on a coastal spit in New Zealand. Both 35 and 200MHz GPR data, which clearly identified a paleosol and internal sedimentary structures of the dune, were used to improve understanding of the development of the dune, which may shed light on paleo-wind directions. Abstract Copyright (2012) Elsevier, B.V.
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13074034 Smith, S. L.; Riseborough, D. W.; Ednie, M. and Chartrand, J. A map and summary database of permafrost temperatures in Nunavut, Canada: Open-File Report - Geological Survey of Canada, Rep. No. 7393, 20 p., illus. incl. tables, 11 ref., 2013. Accessed on Sept. 18, 2013.
A summary database and map of recent permafrost temperatures is provided for Nunavut, Canada. The database includes publicly available information from over 100 boreholes. About 20% of these boreholes are active permafrost thermal monitoring sites maintained by the Geological Survey of Canada and various partners (academic, community, government). Almost 80% of the boreholes were drilled as part of geotechnical investigation programs to support mineral resource development. Most of the ground temperature data provided are based on measurements made since 2000. The map and database provide regional information on permafrost thermal state that can be incorporated into territorial state of knowledge reports and support engineering design and environmental assessment for resource development projects in Nunavut.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13070557 Lewis, Kristen A. (U. S. Geological Survey) and Collett, Timothy S. Brookian sequence well log correlation sections and occurrence of gas hydrates, north-central North Slope, Alaska: Scientific Investigations Report, Rep. No. SIR 2013-5050, 25 p., illus. incl. sects., strat. cols., geol. sketch maps, 50 ref., 2013. Accessed on Aug. 20, 2013.
Gas hydrates are naturally occurring crystalline, ice-like substances that consist of natural gas molecules trapped in a solid-water lattice. Because of the compact nature of their structure, hydrates can effectively store large volumes of gas and, consequently, have been identified as a potential unconventional energy source. First recognized to exist geologically in the 1960s, significant accumulations of gas hydrate have been found throughout the world. Gas hydrate occurrence is limited to environments such as permafrost regions and subsea sediments because of the pressure and temperature conditions required for their formation and stability. Permafrost-associated gas hydrate accumulations have been discovered in many regions of the Arctic, including Russia, Canada, and the North Slope of Alaska. Gas hydrate research has a long history in northern Alaska. This research includes the drilling, coring, and well log evaluation of two gas hydrate stratigraphic test wells and two resource assessments of gas hydrates on the Alaska North Slope. Building upon these previous investigations, this report provides a summary of the pertinent well log, gas hydrate, and stratigraphic data for key wells related to gas hydrate occurrence in the north-central North Slope. The data are presented in nine well log correlation sections with 122 selected wells to provide a regional context for gas hydrate accumulations and the relation of the accumulations to key stratigraphic horizons and to the base of the ice-bearing permafrost. Also included is a well log database that lists the location, available well logs, depths, and other pertinent information for each of the wells on the correlation section.
13074005 Côté, M. M.; Duchesne, C.; Wright, J. F. and Ednie, M. Digital compilation of the surficial sediments of the Mackenzie Valley corridor, Yukon coastal plain, and the Tuktoyaktuk Peninsula: Open-File Report - Geological Survey of Canada, Rep. No. 7289, 38 p., illus. incl. tables; surficial geology maps, 1:125,000; surficial geology maps, 1:250,000, 16 ref., 2013. Accessed on Sept. 18, 2013.
This Geological Survey of Canada Open File presents a digital compilation of previously published surficial geology maps at 1:125,000 and 1:250,000 scale for the Mackenzie River valley, Northwest Territories. The data compilation is presented in ESRI shapefile format and solely identifies surficial materials. The compilation was used as a data source to parameterize surficial materials for ground thermal modeling in the Mackenzie River valley.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13075726 Duchesne, C.; Riseborough, D. W. and Smith, S. L. Air and near surface ground temperatures, indices and summary statistics from 1993 to 2012 for the Mackenzie Valley Corridor, Northwest Territories: Open-File Report - Geological Survey of Canada, Rep. No. 7392, 91 p., illus. incl. tables, 2013. Accessed on Sept. 19, 2013.
Since the early 1990s the Geological Survey of Canada has maintained a network of air and ground surface temperature monitoring sites along a transect in the Mackenzie corridor stretching from the outer Mackenzie Delta to northern Alberta. Data collected from these sites have been utilized to investigate the relationship between air and ground surface temperature for a range of terrain, vegetation and climatic conditions throughout the region. This report presents the data collected up to 2012.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13074024 McMartin, I.; Campbell, J. E.; Dredge, L. A. and McCurdy, M. W. Till composition and ice-flow indicators west of Repulse Bay; 2010 and 2011 results from the GEM Wager Bay surficial geology activity: Open-File Report - Geological Survey of Canada, Rep. No. 7288, 28 p., illus. incl. tables, 80 ref., 2013. Accessed on Sept. 18, 2013.
This Open File report releases the field database and analytical results from the 2010 and 2011 field seasons of the GEM Wager Bay Surficial Geology Activity. The datasets are presented in a format easily importable in a geographic information system (GIS). Quaternary field observations were recorded at 282 field stations; 187 of these included ice-flow indicator measurements. Observations reported for each station include date of collection, location (lat-long and easting-northing, NTS), elevation, observation type, surficial mapping legend unit, landform interpretation and detailed field notes. Ice-flow indicator observations provide information on azimuth, feature type, sense of flow, definition, relative age and relation type (where determined), number of indicators and field notes. Regional surface till samples were collected at 140 of the field observation sites (average 10 km spacing) primarily for both geochemical and indicator mineral analysis. The exceptions were; samples consisting of clayey diamictic layers were collected at three of these sites for only geochemical determination; one beach sample was collected for indicator minerals; and marine mollusk shell samples were collected at 8 sites for radiocarbon age determination. Sample information include location, lithotype, sample depth, soil horizon, purpose and sample size, oxidation state, field colour, matrix and matrix modifier, compaction, water content, HCl reaction, clast %, clast notes, clast roundness, sorting, and additional field notes. Analytical results include till matrix texture and colour, matrix carbon and carbonate contents, pebble count analysis, as well as till matrix geochemistry performed on the <0.063 mm fraction using ICP-MS aqua regia digestion, ICP-MS 4-acid digestion, and ICP-ES/MS lithium borate fusion. Till matrix geochemistry QA/QC analysis was determined using field and analytical duplicates as well as control reference samples (silica blanks and primary standards). The analytical and QA/QC procedures follow the protocols for till samples collected as part of GEM projects (Spirito et al., 2011). Analytical precision indicates results to be reproducible with precision generally classified as good to very good for most elements in results from both years. Limitations include many elements with values too close or below detection limits in the analytical duplicates. Accuracy analysis shows that results are generally within 10% of the mean standard value available for most elements. Blank sample analyses show minimal contamination between samples. Site heterogeneity in geochemical composition was evaluated using field duplicates. Results indicate minor sediment heterogeneity at the sample site and a good reproducibility. With a few exceptions, the analysis of variance for all three geochemical methods indicates that the combined sampling and analytical variability between field duplicate pairs is significantly smaller than the variability between the till sites where the duplicates were collected. This indicates that most elements are suitable for mapping purposes. Heavy mineral processing, precious metal grain counts and indicator mineral picking of potential KIM and MMSIM affinities were completed for each till sample. Contamination, grain carryover, reproducibility and site heterogeneity were evaluated using blanks and field duplicates. Results indicate minor sediment heterogeneity at the sample site and a good reproducibility. Picked grain composition of 301 grains from 2010 was determined using electron microprobe through single point per grain analysis. The 2011 microprobe results as well as the field datasets and analytical results from the 2012 field season will be compiled in a forthcoming second Open File report which will provide an interpretation of till provenance and glacial history, and discuss implications for mineral exploration and land-use management for the entire area north of Wager Bay.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13074021 Normandeau, P. X. (McGill University, Department of Earth and Planetary Sciences, Montreal, QC, Canada) and McMartin, I. Composition of till and bedrock across the Great Bear magmatic zone; Quaternary field database and analytical results from the GEM IOCG-Great Bear Project: Open-File Report - Geological Survey of Canada, Rep. No. 7307, 26 p., illus., 54 ref., 2013. Accessed on Sept. 18, 2013.
This Open File report releases the Quaternary field database and analytical results from the 2009 and 2010 field seasons of the GEM IOCG-Great Bear Project. The datasets are presented in a format easily importable in a geographic information system (GIS). Quaternary field observations were recorded at 270 field stations; 154 of these included either surface expression and/or material modifier description and/or ice-flow indicator measurements (n=165). They depict a discontinuous till cover, sparingly affected by glaciolacustrine reworking below 300 m a.s.l., and a dominant ice-flow direction gradually shifting from west-southwestward in the southern part of the GBmz to west-northwestward in the north. Samples collected include 101 till samples from C-horizon soils, primarily for geochemical and indicator mineral analysis, taken in relation to known mineralization, alteration zones and least altered bedrock, as well as 95 surface bedrock samples for indicator mineral recovery purposes. Analytical results include till matrix texture and color, matrix carbon, pebble analysis, as well as extensive till matrix geochemistry performed on the <0.002 mm and/or <0.063 mm fraction using ICP-MS aqua regia digestion, ICP-MS 4-acid digestion, INAA, and fire assay/ICP-MS. Till matrix geochemistry QA/QC analysis was determined using field and analytical duplicates as well as control reference samples (silica blanks and primary standards). Analytical precision analysis indicates results to be reproducible with precision generally classified as good to very good for most elements in results from both years. Limitations include many elements with values too close or below detection limits in the analytical duplicates. Problematic elements recurring over multiple analytical techniques include: Ag, Au, B, Cd, Hg, In, S, Sb, Se, Re and W. Measurement accuracy analysis shows that results are generally within 10% of the mean standard value available for most elements. Limitations include insufficient material for analysis of some standards. Blank sample analyses show minimal contamination between samples. Field duplicate geochemical analyses suggest the sediment is fairly homogeneous within a site although insufficient data is available to do a full analysis of variance. Mineralogy of the till <0.063 mm fraction of 10 selected samples was determined using QEMSCANTM, giving mineral species identity and proportion under bulk modal analysis, mean grain size frequency per species and grain size distribution per sample. Mineralogy of the till <0.002 mm fraction of 14 selected samples was determined using XRD, giving mineral species identity and proportions. Heavy mineral processing, gold grain counts and indicator mineral picking of potential IOCG affinities were completed on all till and disaggregated bedrock samples. Contamination, grain carryover, reproducibility and site heterogeneity were evaluated using blanks, as well as laboratory and field duplicates. Results indicate minor sediment heterogeneity at the till sample site and a good reproducibility. However, low abundance of some mineral species in till samples may allow for single grain occurrence in only one of both duplicate samples. In 2009, carryover contamination during EPD processing in a specific quartz blank, and to a lesser extent in the following sample, was caused by four heavily mineralized samples from Voisey's Bay (Ni-Cu) and Nevada (Au) introduced in one of the bedrock sample batches. Results suspected to have been affected were removed in a separate sheet. Morphological analysis of representative grains from selected species was performed using binocular, SEM-EDX and SEM-backscatter imagery. Picked grain composition of 433 grains from 2009 and selected species from 496 grains from 2010 was determined using electron microprobe through single point per grain analysis. All presented data is currently being used under a graduate research project by P. Normandeau at McGill University (Normandeau et al., in prep).
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
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