March 2013 Permafrost Alert
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13035152 Eppinger, Robert G. (U. S. Geological Survey, Denver, CO); Fey, David L.; Giles, Stuart A.; Grunsky, Eric C.; Kelley, Karen D.; Minsley, Burke J.; Munk, Leeann and Smith, Steven M. Summary of exploration geochemical and mineralogical studies at the giant Pebble porphyry Cu-Au-Mo deposit, Alaska; implications for exploration under cover: Economic Geology and the Bulletin of the Society of Economic Geologists, 108(3), p. 495-527, illus. incl. sects., 3 tables, sketch maps, 88 ref., May 2013. Includes appendix.
Exploration geochemical and mineralogical studies by the U.S. Geological Survey at the Pebble porphyry Cu-Au-Mo deposit were designed to (1) determine whether the concealed deposit can be detected with surface samples, (2) better understand the processes of metal migration from the deposit to the surface, and (3) test existing methods for assessing concealed mineral resources and/or develop new ones. Surface water (ponds, streams, and springs), pond and stream sediment, soils subjected to various leaching techniques, and glacial till samples were collected. The tilted nature of the undisturbed orebody, varying depth of cover, and later glacial processes, strongly influence the geochemical responses and processes active on the various sample media. The multimedia approach aids in identifying possible processes that caused the significant geochemical variations within and among the various media. These processes include the following: In the Pebble West zone, thin cover and local exposure of the orebody have facilitated the oxidation of pyrite and other sulfides, and associated ferrous-ferric iron reactions, resulting in the local natural acidification of ponds observed in the West zone, and in associated metal anomalies in waters, sediments, and soils. In contrast, the East zone is concealed by both glacial deposits and underlying thick cover rocks, which precludes the oxidation of sulfides in the underlying orebody. Low-level geochemical anomalies in circumneutral spring and pond waters from the East zone are discernible only by using high resolution-inductively coupled plasma-mass spectrometry with lower limits of determination two and perhaps three orders of magnitude lower than traditional methods. A variety of partial leaches of soils over the East zone reveal geochemical anomalies in a similar suite of elements that may be related to upwelling waters from depth along graben-bounding faults. The indicator minerals gold, jarosite, and andradite in till reveal a displaced mineralogical anomaly to the west and south of the Pebble orebody, as ore-related minerals were scraped from the orebody and deposited in till downice of the deposit. Geochemical anomalies in pond water and sediment over the displaced till are attributed to the ore-related minerals in till. This orientation study demonstrates the strong control of local geologic and geochemical settings on the effectiveness of different traditional and newer reconnaissance geochemical exploration techniques and thus has important implications for exploration.
13033986 Anderson, Robert S. (University of Colorado at Boulder, Institute of Arctic and Alpine Research, Boulder, CO); Anderson, Suzanne P. and Tucker, Gregory E. Rock damage and regolith transport by frost; an example of climate modulation of the geomorphology of the critical zone: Earth Surface Processes and Landforms, 38(3), p. 299-316, illus., 80 ref., March 15, 2013.
In this article we craft process-specific algorithms that capture climate control of hillslope evolution in order to elucidate the legacy of past climate on present critical zone architecture and topography. Models of hillslope evolution traditionally comprise rock detachment into the mobile layer, mobile regolith transport, and a channel incision or aggradation boundary condition. We extend this system into the deep critical zone by considering a weathering damage zone below the mobile regolith in which rock strength is diminished; the degree of damage conditions the rate of mobile regolith production. We first discuss generic damage profiles in which appropriate length and damage scales govern profile shapes, and examine their dependence upon exhumation rate. We then introduce climate control through the example of rock damage by frost-generated crack growth. We augment existing frost cracking models by incorporating damage rate limitations for long transport distances for water to the freezing front. Finally we link the frost cracking damage model, a mobile regolith production rule in which rock entrainment is conditioned by the damage state of the rock, and a frost creep transport model, to examine the evolution of an interfluve under oscillating climate. Aspect-related differences in mean annual surface temperatures result in differences in bedrock damage rate and mobile regolith transport efficiency, which in turn lead to asymmetries in critical zone architecture and hillslope form (divide migration). In a quasi-steady state hillslope, the lowering rate is uniform, and the damage profile is better developed on north-facing slopes where the frost damage process is most intense. Because the residence times of mobile regolith and weathered bedrock in such landscapes are on the order of 10 to 100 ka, climate cycles over similar timescales result in modulation of transport and damage efficiencies. These lead to temporal variation in mobile regolith thickness, and to corresponding changes in sediment delivery to bounding streams. Abstract Copyright (2010), John Wiley & Sons, Ltd.
13035125 Bagdanaviciute, Ingrida (Klaipeda University, Coastal Research and Planning Institute, Klaipeda, Lithuania) and Valiunas, Jurijus. GIS-based land suitability analysis integrating multi-criteria evaluation for the allocation of potential pollution sources: Environmental Earth Sciences, 68(6), p. 1797-1812, illus. incl. 7 tables, geol. sketch maps, 39 ref., March 2013.
The geological environment has been heavily polluted by chemical substances over the past few decades. Pollution sources located on the earth's surface or underground have affected the quality of the environment. A significant amount of impact could be reduced if the allocation of potential pollution sources was based on an evaluation of environmental conditions. The main objective of this study was to develop a methodology for the allocation of potential pollution sources by employing GIS and multi-criteria evaluation techniques. This methodology was applied to a study area located in the eastern part of Lithuania. A GIS-based land suitability analysis was performed after identifying 16 factors concerning the geological and socio-economic environment, which were important for environmental protection, land use and spatial planning. The environmental and socio-economic factors were divided into eliminating and limiting criteria. Criteria maps based on the selected factors were compiled. Areas delineated by eliminating criteria were identified as unsuitable for development (according to national legislation). Limiting criteria were evaluated according to the suitability level, which were determined in this study considering the principles of sustainable development. The relative importance of each criterion was assessed utilising the Analytical Hierarchy Process (AHP). A land suitability index (LSI) was calculated and the final result of the land suitability analysis was summarized in three suitability maps (environmental, socio-economic and composite). Four suitability classes (unsuitable, least, moderately and most suitable) for the allocation of potential pollution sources in the study area were used, and the nine most suitable candidate sites were selected according to the proposed methodology. Copyright 2013 Springer-Verlag Berlin Heidelberg and 2012 Springer-Verlag
13035019 Berisso, F. E. (Aarhus University, Department of Agroecology, Tjele, Denmark); Schjonning, P.; Keller, T.; Lamande, M.; Simojoki, A.; Iversen, B. V.; Alakukku, L. and Forkman, J. Gas transport and subsoil pore characteristics; anisotropy and long-term effects of compaction: Geoderma, 195-196, p. 184-191, illus. incl. 4 tables, 43 ref., March 2013.
Anisotropy of soil pore functions significantly affects the transport of gas and water in soil. This paper quantifies anisotropy of subsoil pores and investigates the long-term impact of soil compaction by agricultural machinery. Two long-term field experiments on soil compaction formed the basis for the investigation, one established in 1981 on a clay soil in Finland (60°49'N, 23°23'E) and another in 1995 on a sandy clay loam in Sweden (55°49'N, 13°11'E). In 2009/2010, soil cores were sampled in vertical and horizontal directions from 0.3, 0.5, 0.7 and 0.9 m depth (the two lower depths only in Sweden). In the laboratory, water content, air-filled porosity (ea), air permeability (ka) and gas diffusivity (Ds/D0) were determined at selected matric potentials. For the sandy clay loam, morphological characteristics of pores (effective pore diameter, dB; tortuosity, t; the number of effective pores per unit area, nB) were calculated using a tortuous tube model at -100 hPa matric potential. Blocked air-filled porosity (eb) and a pore continuity index (N) were estimated from the relationship between ka and ea for a range of matric potentials. A factor of anisotropy (FA) was determined as the ratio of a given property measured in the horizontal direction to that in the vertical direction. ka showed anisotropic behaviour (FA<1) for the clay soil and for the 0.3 m depth of the non-compacted sandy clay loam soil, while Ds/D0 displayed anisotropy for the clay soil (FA<1). In the sandy clay loam soil, dB and nB displayed significant anisotropy (FA<1) except at 0.9 m. We interpreted this as effects of biological activities and physical processes in the B-horizon not being active in the C-horizon (0.9 m depth). Compaction generally reduced ka, Ds/D0, dB, nB and increased t for both sampling directions. Compaction had an effect on anisotropy for soil drained to -100 hPa, but only for ka and dB in the sandy clay loam at 0.3 m depth. Compaction reduced anisotropy for the N parameter, i.e. effects on soil pore continuity at the macropore scale, while it increased the anisotropy for eb. Our data thus indicate that compaction had persistent effect on soil physical properties and also affects anisotropy, especially that of macropores. Abstract Copyright (2013) Elsevier, B.V.
13035016 Otero, X. L. (Universidade de Santiago de Compostela, Departamento de Edafoloxía e Química Agrícola, Santiago de Compostela, Spain); Fernández, S.; de Pablo Hernandez, M. A.; Nizoli, E. C. and Quesada, A. Plant communities as a key factor in biogeochemical processes involving micronutrients (Fe, Mn, Co, and Cu) in Antarctic soils (Byers Peninsula, maritime Antarctica): Geoderma, 195-196, p. 145-154, illus. incl. 2 tables, geol. sketch map, 58 ref., March 2013.
The main objective of this study was to establish the effects of plants and microorganisms on soil formation and the geochemical mobility of certain micronutrients in soils from Byers Peninsula (Antarctica). For this purpose, 14 sampling sites were selected to cover the existing range of lithological and geomorphological variability in the area. Soils were sampled at the surface (0-5 cm) and subsurface (from 5 cm to 30 cm or until contact with the bedrock or permafrost). Soil samples were physicochemically characterized by analysis of pH, electrical conductivity, size particle distribution, total organic carbon, total nitrogen and dissolved organic carbon. Sequential extraction of Fe and Mn and of micronutrients (Co, Cu) was also carried out. The analytical results revealed significant differences between sites in relation to plant cover. The total organic carbon was 1.5 times higher, the total nitrogen was 1.6 times higher, the dissolved organic carbon was more than 3.6 times higher and the pHKCl (pH in 0.1 M KCl) was lower in the sites colonized by plants (mainly mosses) than in the sites without any plant cover. The sequential extraction of biolimiting nutrients (Fe, Mn, Co, and Cu) also revealed significant differences in the fractions in relation to the presence of plants. Specifically, the most labile and mobile fractions (amorphous Fe oxyhydroxides, easily reducible Mn, and metals soluble in sodium pyrophosphate) were present at higher concentrations in the sites colonized by vegetation than in the sites without plants. The latter aspect may be of particular importance within the context of global climate change, as increased temperatures will favour expansion of vegetation and the flow of biolimiting nutrients towards oceans and lakes, which may have direct effects on primary productivity. Abstract Copyright (2013) Elsevier, B.V.
13030433 Akerblom, Staffan (Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment, Uppsala, Sweden); Bishop, Kevin; Bjorn, Erik; Lambertsson, Lars; Eriksson, Tobias and Nilsson, Mats B. Significant interaction effects from sulfate deposition and climate on sulfur concentrations constitute major controls on methylmercury production in peatlands: Geochimica et Cosmochimica Acta, 102, p. 1-11, illus. incl. 4 tables, 88 ref., February 1, 2013.
Transformation of inorganic mercury (Hg) to methyl mercury (MeHg) in peatlands is a key process in making boreal catchments a source of MeHg to freshwater ecosystems. Due to the importance of sulfur-reducing bacteria (SRB) for this process, past atmospheric deposition of sulfate (SO42-) may have increased net terrestrial Hg methylation. A long-term (14-year) factorial design field experiment was used to investigate the effect of enhanced SO42- deposition and raised temperature using a greenhouse (GH) treatment (air temperature~+4°C; soil temperature 20 cm below mire surface ~+2°C) on sulfur (S) turnover, net Hg methylation, MeHg and total Hg concentrations in a boreal mire in northern Sweden. Of the SO42--S added during 14 years, 50% was retained in the plots without GH treatment while the combination of SO42- addition and GH treatment resulted in 15% S retention. The addition of SO42- (7-fold ambient SO42--deposition) increased (p<0.05) the net Hg methylation (200%) as well as the store of S (150%) and MeHg (120%) in the peat. A combination of enhanced SO42- deposition and GH treatment decreased both the net Hg methylation rate constant (0.018±0.006 d-1) and MeHg content (1.2±0.2 ng g-1 dry weight (dw)) relative to the sites with enhanced SO42- deposition without GH treatment (0.065±0.013 d-1 and 3.7±0.6 ng g-1dw, respectively). The concentration of Hg in the peat declined (p<0.05) in response to experimental addition of SO42-. Despite the decrease in Hg in response to SO42- deposition, these plots had the highest amounts of MeHg as well as the highest Hg methylation rate constants. This indicates that the concentration of S is more important than the concentration of Hg for the production of MeHg in this boreal landscape. These results also show that long-term chronic SO42- deposition at rates similar to those found in polluted areas of Europe and North America increase the capacity of wetlands to methylate Hg and store MeHg, which can ultimately be released to streams and lakes. This study also, for the first time, indicates that the enhancing effect of SO42- on the production of MeHg might be counteracted by increased temperature. Abstract Copyright (2013) Elsevier, B.V.
13030632 Buchli, Thomas (Swiss Federal Institute of Technology, Institute for Geotechnical Engineering, Zurich, Switzerland); Merz, Kaspar; Zhou, Xiaohai; Kinzelbach, Wolfgang and Springman, Sarah M. Characterization and monitoring of the Furggwanghorn rock glacier, Turtmann Valley, Switzerland; results from 2010 to 2012: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 1 table, sketch map, 67 ref., February 2013. Supplemental information/data is available in the online version of this article.
Climate effects relating to air temperature, radiation, snow cover, and rainfall combine with thaw and infiltration processes to cause changes in the thermal response and associated creep deformations in rock glaciers, which are the geomorphological expression of Alpine permafrost. The annual surface creep of some rock glaciers has accelerated recently by an order of magnitude. A multidisciplinary field study links characterization, monitoring, and modeling for such a rock glacier in the Turtmann valley in Switzerland. The first phase consisted of characterization using seismic refraction and ground-penetrating radar (GPR), as well as borehole information and monitoring of meteorological, hydrothermal, and geotechnical variables over 2 yr. The ground model confirmed the heterogeneity of the internal structure, with rock glacier topography affecting the thermal distribution in boreholes and seepage flows from tracer tests at between 10 and 40 m h-1. Temperatures were generally warmer than -0.25°C in the permafrost zone, with some variability in terms of thermal degradation of some layers to 0°C and an active layer of about 3 to 5 m depth. Unique internal shear movements were measured by an automatic inclinometer, which indicated downslope creep rates in the shear zone and at the surface of about 2.4 and 3.2 m yr-1 respectively, which could not be directly linked to temperature at the same depth. These rock glaciers have potential for future instability, which could damage infrastructure in the valley below. It is essential to understand why they have accelerated over the past decade through the complex interactions that have controlled the thermo-hydromechanical response.
13032228 Christiansen, Hanne H. (University Centre in Svalbard, Arctic Geology Department, Longyearbyen, Norway); Humlum, Ole and Eckerstorfer, Markus. Central Svalbard 2000-2011 meteorological dynamics and periglacial landscape response: Arctic, Antarctic, and Alpine Research, 45(1), p. 6-18, illus. incl. sketch map, 36 ref., February 2013.
Local mountain meteorology of the landscape around Longyearbyen in central Svalbard is analyzed through the decade from 2000 to 2011. Standard meteorological stations from close to sea level and up to 464 m a.s.l. located on different periglacial landforms, have been used. During winters with little sea ice, strong temperature inversions do not develop, and then there is a distinct cooling with height, as opposed to when sea ice is present. Airflow is accelerated due to topography and direction deflected in the confined valleys, whereas open plateaus have on average 1 m/s lower wind speeds with a regional SE direction. The permafrost thermal state is largely controlled by meteorology, with permafrost in the valley bottoms as cold as on the mountain plateaus. The periglacial landform most exposed to climatic variability is ice-wedges, which seem to crack mainly during shorter cooling periods. Such activity is also linked to temperature inversions, and thus also occur mainly when sea ice is present. Solifluction is mainly controlled by the balance between summer thawing and winter freezing in combination with snow dynamics, whereas avalanches are mainly wind controlled. Avalanches and avalanche controlled landforms are least sensitive to climatic variability.
13030640 Groenevelt, Pieter H. (University of Guelph, School of Environmental Sciences, Guelph, ON, Canada) and Grant, Cameron D. Heave and heaving pressure in freezing soils; a unifying theory: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 3 tables, 42 ref., February 2013.
A unifying theory is presented for the process of heave in freezing soils. Out of the Cold Regions Research and Engineering Laboratory (CRREL) school of D.M. Anderson came the concept of the segregation potential. Out of the Cornell school of R.D. Miller came the model for the heave rate. Here ideas from both schools are put on a fundamental thermodynamic footing, leading to the definition of a new heave index. Both schools use the temperature gradient in the frozen fringe as the driving force for heave. We argue and demonstrate that this choice leads to erratic results. The driving force should be the temperature gradient over the complete layer of soil that is at sub-zero (°C) temperature, that is, the combined frozen zone plus the frozen fringe. The value of the heave index is completely dominated by the unsaturated hydraulic conductivity function of both the unfrozen soil below the frozen fringe and the soil layer at sub-zero temperature.
13030635 He, Hailong (University of Alberta, Department of Renewable Resources, Edmonton, AB, Canada) and Dyck, Miles. Application of multiphase dielectric mixing models for understanding the effective dielectric permittivity of frozen soils: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 4 tables, 72 ref., February 2013.
The time domain reflectometry (TDR)-measured effective permittivity in frozen soil conditions is affected by many complex factors including bound water effects on soil water permittivity, phase changes, soil microstructure and relative positions of soil constituents with respect to each other. The objective of this study was to improve understanding of some of the factors affecting the effective permittivity of frozen soils through the use of dielectric mixing models. Published datasets and frozen and unfrozen soil data measured on western Canadian soils were investigated with multiphase discrete and confocal ellipsoid models available in the literature. The results revealed that adjusting model parameters allowed the mixing models to describe the frozen soil permittivity equally well when bound water effects and temperature-dependent water permittivity effects were included or not included. Measurement of freezing and thawing curves on western Canadian soils showed significant hysteresis and some mechanisms for this observed hysteresis and its influence on the interpretation of published datasets are discussed. When independent measurements of liquid water, ice and effective permittivity are available, it is possible to find one set of model parameters that reasonably predict effective permittivity for both frozen and unfrozen conditions. In frozen soils the predictive capability of the models is constrained to scenarios where the initial water content prior to freezing (i.e., the total water content) in the sampling volume is constant.
13030639 Kojima, Yuki (Iowa State University, Agronomy Department, Ames, IA); Heitman, Joshua L.; Flerchinger, Gerald N. and Horton, Robert. Numerical evaluation of a sensible heat balance method to determine rates of soil freezing and thawing: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 4 tables, 54 ref., February 2013.
In situ determination of soil freezing and thawing is difficult despite its importance for many environmental processes. A sensible heat balance (SHB) method using a sequence of heat pulse probes has been shown to accurately measure water evaporation in subsurface soil, and it has the potential to measure soil freezing and thawing. Determination of soil freezing and thawing may be more challenging than evaporation, however, because the latent heat of fusion is smaller than the latent heat of vaporization. Furthermore, convective heat flow associated with liquid water flow and occurrence of evaporation or condensation during freezing and thawing may cause inaccurate estimation of freezing and thawing with the SHB method. The objective of this study was to examine the applicability of the SHB concept to soil freezing and thawing. Soil freezing and thawing events were simulated with the simultaneous heat and water (SHAW) model. Ice contents were estimated by applying the SHB concept to numerical data produced by the SHAW model. Close agreement between the SHB-estimated and the SHAW-simulated ice contents were observed at depths below 24 mm. The main cause of inaccuracies with the SHB method was poor estimation of heat conduction at the 12-mm depth, possibly due to simplifications of temporal or vertical distributions of temperature and thermal conductivity. The effects of convective heat flow and concurrent evaporation or condensation and freezing or thawing on the SHB method were small. The results indicate that the SHB method is conceptually suitable for estimating soil freezing and thawing. Independent, accurate estimates of thermal properties must be available to effectively use the SHB method to determine in situ soil freezing and thawing.
13030638 Kozlowski, Tomasz (Kielce University of Technology, Department of Geotechnical and Water Engineering, Kielce, Poland) and Nartowska, Edyta. Unfrozen water content in representative bentonites of different origin subjected to cyclic freezing and thawing: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 7 tables, 34 ref., February 2013.
The unfrozen water content in frozen soils strongly influences heat and mass transport processes. Despite massive research work, the actual implications of the freeze-thaw process on unfrozen water still remain unknown. The main objective of this study was to examine the hypothetical effect of a number of previous freeze-thaw cycles on the unfrozen water content during the current cycle. Several bentonites (Stx-1b from Wyoming, SWy-2 from Texas, as well as Ca, Na, and K forms of bentonite from Chmielnik) with different water contents were subjected to repeated freezing to -90°C and thawing at 20°C in a differential scanning calorimeter (DSC). The total number of cycles was five. The unfrozen water contents were determined on warming during each cycle by the use of the stochastic deconvolution of the DSC signal. According to the ANOVA results, the freeze-thaw effect on the unfrozen water content wu in the bentonites was not statistically significant. A clear pattern of alterations of wu with the number of consecutive cycles could be distinguished, however, depending on the major exchangeable cation. The kind of exchangeable cation played a predominant role in the temperature dependence of the unfrozen water content. The specific surface area strongly affected the unfrozen water content at lower temperatures, i.e., at -5°C and below. Closer to 0?°C, the effect of the specific surface became absolutely insignificant, and the clay fraction content determined by the laser diffraction method proved to be the soil property best correlating with the unfrozen water content at -1°C.
13030637 Lafrenière, Melissa J. (Queen's University, Department of Geography, Kingston, ON, Canada); Laurin, Emil and Lamoureux, Scott F. The impact of snow accumulation on the active layer thermal regime in high Arctic soils: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 4 tables, sketch map, 40 ref., February 2013.
This study quantifies the impacts of snow augmentation and the timing of snow accumulation on the soil thermal regime at the Cape Bounty Arctic Watershed Observatory (CBAWO), in the Canadian High Arctic. Monthly soil temperatures between December and March 2006-2007 were 7.7 to 9.9°C warmer beneath a deep drift (54 cm) relative to soils beneath ambient (unamended or background) snow conditions (10 cm). Although air temperatures and total snow accumulation at the sites in 2007-2008 were very similar to the previous winter, the mean monthly soil temperatures beneath two snow drifts (50 and 88 cm) were only 0.2 to 5.7°C warmer for January through March than soils subject to ambient snow depths (18 and 35 cm). Results demonstrate that the timing of snow accumulation was more important than snow depth in determining winter soil temperatures. In 2006-2007, snow cover insulated soils by early November, while in 2007-2008 there was insufficient snow cover to insulate soils until late January 2008. In 2006-2007, winter (December-March) soil temperatures beneath the deepest snow (54 cm) exceeded winter air temperatures by 6°C, and mean annual air temperatures by 1°C, while in 2007-2008 winter soil temperatures beneath 88 cm of snow were only 0.3°C warmer than air, and mean annual temperatures were 2.4°C cooler than air. There was a weak but significant inverse correlation between the maximum active layer thickness and the snow depth; however, this correlation was more pronounced for snow depths below approximately 30 cm. This study demonstrates that an understanding of the timing of projected increases in winter precipitation is necessary to predict changes in the active layer's thermal, hydrological, and biogeochemical response to regional climate change.
13030455 Leybourne, Matthew I. (ALS Geochemistry, North Vancouver, BC, Canada); Cameron, Eion M.; Reich, Martin; Palacios, Carlos; Faure, Kevin and Johannesson, Karen H. Stable isotopic composition of soil calcite (O, C) and gypsum (S) overlying Cu deposits in the Atacama Desert, Chile; implications for mineral exploration, salt sources, and paleoenvironmental reconstruction: Applied Geochemistry, 29, p. 55-72, illus. incl. 1 table, sketch map, 103 ref., February 2013.
Soils overlying two porphyry Cu deposits (Spence, Gaby Sur) and the Pampa del Tamarugal, Atacama Desert, Northern Chile were collected in order to investigate the extent to which saline groundwaters influence "soil" chemistry in regions with thick Miocene and younger sediment cover. Soil carbonate (calcite) was analyzed for C and O isotopes and pedogenic gypsum for S isotopes. Soil calcite is present in all soils at the Spence deposit, but increases volumetrically above two fracture zones that cut the Miocene gravels, including gravels that overlie the deposit. The C isotope composition of carbonate from the soils overlying fracture zones is indistinguishable from pedogenic carbonate elsewhere at the Spence deposit; all d13CVPDB values fall within a narrow range (1.40-4.23 ppm), consistent with the carbonate having formed in equilibrium with atmospheric CO2. However, d18OVPDB for carbonate over both fracture zones is statistically different from carbonate elsewhere (average d18OVPDB=0.82 ppm vs. -2.23 ppm, respectively), suggesting involvement of groundwater in their formation. The composition of soils at the Tamarugal anomaly has been most strongly affected by earthquake-related surface flooding and evaporation of groundwater; d13CVPDB values (-4.28 ppm to -2.04 ppm) are interpreted to be a mixture of dissolved inorganic C (DIC) from groundwater and atmospheric CO2. At the Spence deposit, soils only rarely contain sufficient SO4 for S isotope analysis; the SO4-bearing soils occur only above the fracture zones in the gravel. Results are uniform (3.7-4.9 ppm d34SCDT), which is near the middle of the range for SO4 in groundwater (0.9-7.3 ppm). Sulfur in soils at the Gaby Sur deposit (3.8-6.1 ppm d34SCDT) is dominated by gypsum, which primarily occurs on the flanks and tops of hills, suggesting deposition from SO4-rich fogs. Sulfate in Gaby Sur deposit gypsum is possibly derived by condensation of airborne SO4 from volcanic SO2 from the nearby Andes. At the Gaby Sur deposit and Tamarugal anomaly, pedogenic stable isotopes cannot distinguish between S from porphyry or redeposited SO4 from interior salars. The three sites studied have had different histories of salt accumulation and display variable influence of groundwater, which is interpreted to have been forced to the surface during earthquakes. The clear accumulation of salts associated with fractures at the Spence deposit, and shifts in the isotopic composition of carbonate and sulfate in the fractures despite clear evidence of relatively recent removal of salts indicates that transfer from groundwater is an ongoing process. The interpretation that groundwaters can influence the isotopic composition of pedogenic calcrete and gypsum has important implications for previous studies that have not considered this mechanism. Abstract Copyright (2013) Elsevier, B.V.
13028520 Obermiller, Kyle E. (University of Alaska at Fairbanks, Fairbanks, AK); Darrow, Margaret M.; Huang, Scott L. and Chen, Gang. Site investigation and slope stability analysis of the Chitina Dump Slide (CDS), Alaska: Environmental & Engineering Geoscience, 19(1), p. 27-40, illus. incl. 2 tables, sketch map, 35 ref., February 2013.
We present the mapping and subsurface analysis of a slide occurring in discontinuous permafrost located near Chitina, AK. Our investigation included mapping landslide features, conducting seismic surveys, collecting tree-ring samples for dendrogeomorphic analysis, and conducting a slope stability analysis to back-calculate residual soil strength properties. Referred to as the "Chitina Dump Slide" because of its previous use as a dump, the active slide intersects a state road and is an ongoing maintenance issue. The soils in the area consist of surficial silt overlying clayey glaciolacustrine diamicton, overlying bedrock. Drilling data indicated the deepening of the permafrost table in the active slide area from 6.1 m in 2005 to greater than 16.5 m in 2010. Field mapping indicated that the landslide extent is much larger than the active portion of the slide. The dendrogeomorphic analysis indicated that movement occurred in at least two portions of the area in the 1940s and in a third area later in the 1990s. Seismic surveys, with typical velocities ranging from 100 to 900 m/s, produced good correlation with drilling data and proved to be an effective method of subsurface imaging. From these observations, we conclude that the failure mechanism for the active portion of the slide is different than that of the overall slide area. Back-calculation of slope failure within the clay layer indicates a residual effective friction angle of 22°. Permafrost degradation due to the thermal effects of the dump may be a contributing factor in the ongoing movement of the active slide area.
13032231 Paré, Maxime C. (Agrinova, Alma, QC, Canada) and Bedard-Haughn, Angela. Surface soil organic matter qualities of three distinct Canadian Arctic sites: Arctic, Antarctic, and Alpine Research, 45(1), p. 88-98, illus. incl. 3 tables, sketch maps, 96 ref., February 2013.
Cryosolic soils store large amounts of carbon (C) because soil organic matter (SOM) decomposition is slower than plant growth. The response of arctic SOM to climate change is likely to depend not only on temperature, but also upon complex interactions between soil properties and SOM chemistry. We hypothesized that organic surface soils (>17% carbon) have more labile SOM than mineral surface soils (<17% carbon). Furthermore, we hypothesized that high arctic soils have more labile SOM than soils from the Low Arctic and subarctic. This study was conducted in 3 arctic ecosystems: subarctic (Churchill, Manitoba; n = 138), Low Arctic (Daring Lake, Northwest Territories;n = 60), and High Arctic (Truelove Lowlands, Nunavut; n = 54). The 0-10 cm depth of several different Cryosolic soils was sampled. The results from density fractionation and solid-state 13C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy showed that organic surface soils contained relatively more labile C than mineral surface soils. Organic soils contained about 13% more O-Alkyl-C and 30% less Aromatic-C than mineral soils. Furthermore, for Churchill, Daring Lake, and Truelove organic soils, 53, 73, and 20% of the C was included in the light fraction of SOM [LF (LF < 1.55 g mL-1)], whereas 24, 19, and 14% of the C was included in the LF of mineral soils, respectively. Organic surface soils of subarctic and low arctic sites contained relatively more labile C than the high arctic site. Results showed that the subarctic and low arctic sites store about 15% more O-alkyl-C and 35% less Aromatic-C than high arctic organic soils (P < 0.001).
13030631 Parkin, Gary (University of Guelph, School of Environmental Sciences, Guelph, ON, Canada); von Bertoldi, Axel P. and McCoy, Amber J. Effect of tillage on soil water content and temperature under freeze-thaw conditions: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 2 tables, 29 ref., February 2013.
High resolution (hourly) soil water content and temperature data have been collected for nearly 10 yr within the 0-100 cm depth profiles under no-till (NT) and conventional fall tillage (CT) practices. The data indicate significant differences between the two tillage practices, especially during winter and early spring freeze\thaw cycles. Results indicate that shallow minimum soil temperatures were lower under CT than NT; however, average winter shallow soil temperatures were very similar between the two treatments. Soil freezing characteristic curves (SFC) measured in situ with soil water content and temperature data were analyzed for differences between treatments as the NT system matured. The SFC shapes for NT evolved over a 7-yr period as the age of the NT system increased. An intensive freeze-thaw episode showed strong hysteresis in SFC, a phenomenon not analyzed in detail before this study based on data collected in the field.
13030629 Toride, Nobuo (Mie University, Graduate School of Bioresources, Japan); Watanabe, Kunio and Hayashi, Masaki, editors. Progress in modeling and characterization of frozen soil processes: Vadose Zone Journal, 12(1), illus., February 2013. Individual papers are cited separately.
13030630 Watanabe, Kunio (Mie University, Graduate School of Bioresources, Tsu, Japan); Kito, Tetsuya; Dun, Shuhui; Wu, Joan Q.; Greer, R. Cory and Flury, Markus. Water infiltration into a frozen soil with simultaneous melting of the frozen layer: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus., 35 ref., February 2013.
Understanding water infiltration into frozen soil is important for preventing soil erosion and managing soil water and nutrients. In this study, we performed a column experiment on infiltration through frozen soil using a variably-saturated silt loam. Three soil columns (7.8 cm i.d., 35 cm long), with three different initial soil water contents, were cooled from the top to form a frozen layer of the same thickness. The columns were instrumented with 34 thermocouples, seven time-domain reflectometry (TDR) probes, and seven tensiometers. Water at a temperature of 3.5°C was applied to the top of the columns with a 15-cm constant head. We monitored ice and liquid water contents, temperatures, and the position of the infiltration front. Three phases of infiltration were observed: (i) no infiltration at the beginning, (ii) slow infiltration as the infiltration front advanced through the frozen layer, and (iii) increased infiltration as the infiltration front advanced through the unfrozen soil below the frozen layer. The duration of each phase became longer with increasing initial soil water content as the infiltration rate of each phase decreased. The volumetric ice content and thickness of the frozen layer controlled the infiltration process. We use a capillary bundle model to characterize the hydraulic conductivity as a function of ice content during infiltration. Based on our experimental data and results, we mechanistically describe the water infiltration into frozen soil.
13030633 Wu, Yuxin (Lawrence Berkeley National Laboratory, Berkeley, CA); Hubbard, Susan S.; Ulrich, Craig and Wullschleger, Stan D. Remote monitoring of freeze-thaw transitions in arctic soils using the complex resistivity method: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus., 84 ref., February 2013.
Our ability to monitor freeze-thaw transitions is critical to developing a predictive understanding of biogeochemical transitions and carbon dynamics in high latitude environments. In this study, we conducted laboratory column experiments to explore the potential of the complex resistivity method for monitoring the freeze-thaw transitions of the arctic permafrost soils. Samples for the experiment were collected from the upper active layer of Gelisol soils at the Barrow Environmental Observatory (BEO) in Barrow, Alaska. Freeze-thaw transitions were induced through exposing the soil column to controlled temperature environments at 4 and -20°C. Complex resistivity and temperature measurements were collected regularly during the freeze-thaw transitions using electrodes and temperature sensors installed along the column. During the experiments, over two orders of magnitude of resistivity variations were observed when the temperature was increased or decreased between -20 and 0°C. Smaller resistivity variations were also observed during the isothermal thawing or freezing processes that occurred near 0°C. Single frequency electrical phase response and imaginary conductivity at 1 Hz were found to be exclusively related to the unfrozen water in the soil matrix, suggesting that these geophysical attributes can be used as a proxy for the monitoring of the onset and progression of the freeze-thaw transitions. Spectral electrical responses and fitted Cole-Cole parameters contained additional information about the freeze-thaw transition affected by the soil grain size distribution. Specifically, a shift of the observed spectral response to lower frequency was observed during the isothermal thawing process, which we interpret to be due to sequential thawing, first from fine particles and then to coarse particles within the soil matrix. Our study demonstrates the potential of the complex resistivity method for remote monitoring of freeze-thaw transitions in arctic soils. Although conducted at the laboratory scale, this study provides the foundation for exploring the potential of the complex resistivity signals for monitoring spatiotemporal variations of freeze-thaw transitions over field-relevant scales.
13030598 Zak, Karel (Academy of Sciences of the Czech Republic, Institute of Geology, Prague, Czech Republic); Orvosova, Monika; Filippi, Michal; Vlcek, Lukas; Onac, Bogdan P.; Persiu, Aurel; Rohovec, Jan and Svetlik, Ivo. Cryogenic cave pearls in the periglacial zones of ice caves: Journal of Sedimentary Research, 83(2), p. 207-220, illus. incl. 3 plates, 3 tables, sketch maps, 55 ref., February 2013.
The Carpathian Mountains across Slovakia and Romania are home of several ice caves located at elevations between 700 and 1,200 m above sea level (asl). Although the mean surface annual temperature is above the freezing point, perennial ice deposits are common in caves and shafts with certain morphologies (large entrances followed by steep vertical or downward-sloping passages), into which the dense cold winter air sinks and remains trapped all year round. A particular type of cave pearls (cryogenic cave pearls, CCPs) occur in spatially restricted accumulations or extensive pearl fields (layers locally up to 0.5 m in thickness) within the scree covering the cave floor in the periglacial zone of these caves. The temperature in the periglacial zone oscillates around the freezing point, promoting seasonal ice formation. A similar type of pearl is observed in the entrance section of other caves that experience temporary freezing conditions during the cold season. When compared to pearls of non-iced caves, those from ice caves always occur at sites where liquid water cannot accumulate. CCP formation in nests with drips or in cave pools surrounded by rimstone dams is therefore excluded. Freezing-thawing processes are responsible for moving the pearls, preventing their cementation to the floor or between them. Results of U-series and radiocarbon dating indicate that the pearls are Holocene in age, with their growth continuing into the present. Pearls show high porosity, ranging from 7.6 to 22.6%. In the center they frequently contain radial aggregates of larger carbonate crystals, and their concentric layering is less obvious compared to normal cave pearls. In addition, polygonal pearls and pearl aggregates are common. Stable carbon and oxygen isotope study indicates the formation of an initial crystal aggregate by cryogenic precipitation during freezing of drip water. After that, pearls grow by addition of new carbonate layers, either at water freezing conditions or at temperature above 0°C. Overall, the pearl isotope data plot along a mixing line in the d13C vs. d18O diagram, connecting the field of normal speleothems of non-iced caves of the area, with the field of fine-grained cryogenic carbonate powder, formed in the glaciated parts of the ice caves. Seasonal water freezing and frost action in the cave periglacial zone is a necessary condition for the formation of these pearls.
13030634 Zhao, Ying (University of Tokyo, Department of Biological and Environmental Engineering,, Tokyo, Japan); Nishimura, Taku; Hill, Robert and Miyazaki, Tsuyoshi. Determining hydraulic conductivity for air-filled porosity in an unsaturated frozen soil by the multistep outflow method: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 1 table, 30 ref., February 2013.
Accurate simulation of snowmelt infiltration and runoff in frozen soil is important for many environmental and engineering issues in cold regions. It is well known that infiltration in frozen soil is dramatically reduced due to the impedance of ice crystals; however, it is very often inaccurately predicted because of limited data to parameterize the related processes. In this study, the hydraulic conductivity K(h) for air-filled porosity in an unsaturated frozen soil was investigated by employing a multistep pressurized outflow method using antifreeze liquid. Comparisons of water flow in both partially frozen and unfrozen soils indicated that frozen soil significantly reduced K(h) due to the blocking effects of ice crystals. Based on one common K(h)-based hydraulic equation, an impedance parameter for liquid-filled porosity was extended to an apparent impedance parameter for air-filled porosity. The apparent impedance factor Wa is about 4 ranging from 0.5 to 6.5 as a function of matric potential. These findings represent significant new progress for estimation of Wa by an experimental method that can be used for the estimation of snowmelt infiltration. We suggest that the current applied measurement method should be used and further evaluated for a variety of soil types.
13030636 Zhao Ying (Northwest A&F University, Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Yangling, China); Huang Mingbin; Horton, Robert; Liu Feng; Peth, Stephan and Horn, Rainer. Influence of winter grazing on water and heat flow in seasonally frozen soil of Inner Mongolia: in Progress in modeling and characterization of frozen soil processes (Toride, Nobuo, editor; et al.), Vadose Zone Journal, 12(1), illus. incl. 2 tables, sketch map, 32 ref., February 2013.
Snowmelt infiltration and soil thawing processes are essential for understanding surface and subsurface hydrology under the cold and arid climatic conditions found in grazed Inner Mongolia grassland soils. Over a 6-yr period (2004-2009), we evaluated the effects of winter grazing and freezing/thawing cycles on (i) soil hydraulic and thermal properties, (ii) the dynamics of field soil moisture and temperature, and (iii) the contributions of snowmelt and soil thawing to the summer water balance. Two adjacent contrasting sites were selected: a site that has been ungrazed since 1999 (UG99), and a site that has been grazed during the winter (WG). The results showed that the freezing/thawing cycles changed soil hydraulic and thermal properties. Associated with those freezing-induced changes, winter grazing decreased soil moisture by 5-10% throughout the whole year (October 2005 to September 2006), increased soil temperature by 1 to 3°C in summer, and decreased it by 2 to 5°C in winter. The grazed site with lower vegetation/snow cover and larger thermal conductivity had greater freezing rates and larger soil temperature fluctuations on a daily scale than the ungrazed site. Winter precipitation (snow + rainfall) contributed 15% of the total annual water balance for the UG99 site, but only 11% for WG site. We concluded that a detailed analysis of the spring snowmelt infiltration was critical for calculating seasonal water and energy balances in this region to fully understand the hydrological and ecological processes.
13033788 Bockheim, J. (University of Wisconsin at Madison, Department of Soil Science, Madison, WI); Vieira, G.; Ramos, M.; López-Martínez, J.; Serrano, E.; Guglielmin, M.; Wilhelm, K. and Nieuwendam, A. Climate warming and permafrost dynamics in the Antarctic Peninsula region: Global and Planetary Change, 100, p. 215-223, illus. incl. 1 table, sketch map, 78 ref., January 2013.
Dramatic warming of the climate over the last several decades has influenced the properties and distribution of permafrost in the Antarctic Peninsula region. Five approaches were used to estimate the distribution of permafrost in the region: (1) correlation of permafrost distribution with mean annual air temperature isotherms, (2) mapping the distribution of periglacial features indicative of permafrost, (3) summarizing data from shallow excavations and boreholes, (4) detection of permafrost from geophysical techniques, and (5) application of models to predict the occurrence of permafrost. Whereas permafrost is continuous in the South Orkney Islands (60-61°S) and along the eastern Antarctic Peninsula (63-65°S), it is discontinuous in the South Shetland Islands (62-63°S), and occurs only sporadically in the Palmer Archipelago and Biscoe Islands along the western Antarctic Peninsula (64-66°S). Permafrost then becomes continuous on Alexander Island (71-74°S) along the western Antarctic Peninsula as the maritime climate shifts to a more continental climate. Reports prior to 1980 mention the presence of permafrost at depths of 25 to 35 cm in ice-free areas near Palmer Station (64°46'S; 64°04'W), where the mean annual air temperature from extrapolation of data from the nearby Vernadsky Station has increased 3.4°C and the mean winter temperature has increased 6°C since 1950. Recent measurements suggest that permafrost is absent or close to 0°C in the upper 14 m of the highest ice-free areas (67 m a.s.l.) near Palmer Station. Permafrost temperatures elsewhere along the western Antarctic Peninsula region range from -0.4 to -1.8°C in the South Shetland Islands (62-63°S) to -3.1°C at Adelaide Island (67°34'S). Permafrost at this temperature is susceptible to thawing, which has resulted in historic increases in active-layer thicknesses and in thermokarst features such as debris flows, and active-layer detachment slides. Abstract Copyright (2013) Elsevier, B.V.
13032201 Nutz, Alexis (Université de Strasbourg, Institut de Physique du Globe de Strasbourg, Strasbourg, France); Ghienne, Jean-François and Storch, Petr. Circular, cryogenic structures from the Hirnantian deglaciation sequence (Anti-Atlas, Morocco): Journal of Sedimentary Research, 83(1), p. 115-131, illus. incl. sects., geol. sketch map, 78 ref., January 2013.
More than a hundred circular structures are observed at the topmost part of the Late Ordovician glaciogenic record in the central Anti-Atlas, southern Morocco. The structures were formed in the outer glaciated platform and characterize the Hirnantian deglaciation sequence. They are distributed within a 20 meter thick stratal interval and, at present, relicts of them still occupy several square kilometers in map view. The circular to ovoidal structures, which comprise fluvial sandstone beds and are sealed by shallow marine strata, occur in closely spaced clusters. They are 13-320 m in diameter, with half of them in the 40-90 m range. Stratal wedging and bending, as well as extensional and reverse centimeter- to meter-scale soft-sediment fractures, demonstrate that formation processes initially involved synsedimentary uplifts. Subsequent subsidence and collapse resulted in the formation of circular structures, which essentially correspond to localized depocenters in the form of small-scale sag basins. Regarding the overall deglaciation context, the circular structures are interpreted as periglacial in origin, with vertical movements ascribed to cryogenic processes involving the growth and then decay of bodies of segregation ice. The size and diameter distributions, which are comparable to the recent (Younger Dryas) and current lithalsa structures, suggest that Hirnantian circular features relate to similar genetic processes and can be referred to as lithalsa-like structures. A conceptual emplacement model is proposed, which considers that a long-term sedimentary aggradation over the fluvial plain prevented any significant landforms (either a bump or a depression) from being expressed at the depositional surface at the time of the circular structure formation. The Hirnantian lithalsa-like structures constitute firm evidence for a Late Ordovician discontinuous permafrost during the deglaciation stage. Assuming that the late Quaternary meridional zonation is valid, it suggests the Anti-Atlas was at latitudes in the 55-65° interval. If combined with the rare pingo structures described in the literature, which attest that coeval continuous permafrost conditions occurred at higher paleo-latitudes, the Moroccan circular structures provide evidence for an alternate South Pole position during the Hirnantian (444 Ma).
13031684 Lachniet, Matthew S. (University of Nevada at Las Vegas, Las Vegas, NV); Lawson, Daniel E. and Sloat, Alison R. Revised 14C dating of ice wedge growth in interior Alaska (USA) to MIS 2 reveals cold paleoclimate and carbon recycling in ancient permafrost terrain: Quaternary Research, 78(2), p. 217-225, illus. incl. 2 tables, sketch map, 47 ref., September 2012.
Establishing firm radiocarbon chronologies for Quaternary permafrost sequences remains a challenge because of the persistence of old carbon in younger deposits. To investigate carbon dynamics and establish ice wedge formation ages in Interior Alaska, we dated a late Pleistocene ice wedge, formerly assigned to Marine Isotope Stage (MIS) 3, and host sediments near Fairbanks, Alaska, with 24 radiocarbon analyses on wood, particulate organic carbon (POC), air-bubble CO2, and dissolved organic carbon (DOC). Our new CO2 and DOC ages are up to 11,170 yr younger than ice wedge POC ages, indicating that POC is detrital in origin. We conclude an ice wedge formation age between 28 and 22 cal ka BP during cold stadial conditions of MIS 2 and solar insolation minimum, possibly associated with Heinrich event 2 or the last glacial maximum. A DOC age for an ice lens in a thaw unconformity above the ice wedge returned a maximum age of 21,470±200 cal yr BP. Our variable 14C data indicate recycling of older carbon in ancient permafrost terrain, resulting in radiocarbon ages significantly older than the period of ice-wedge activity. Release of ancient carbon with climatic warming will therefore affect the global 14C budget. Abstract Copyright (2012) Elsevier, B.V.
13028529 O'Neill, H. Brendan (Carleton University, Department of Geography and Environmental Studies, Ottawa, ON, Canada) and Burn, C. R. Physical and temporal factors controlling the development of near-surface ground ice at Illisarvik, western Arctic Coast, Canada: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, 49(9), p. 1096-1110, illus. incl. strat. col., 1 table, geol. sketch map, 35 ref., September 2012.
Near-surface permafrost was sampled in summer 2010 at 26 sites in the Illisarvik drained-lake basin and nine sites in the surrounding tundra on Richards Island, NWT, to investigate the growth of segregated near-surface ground ice. Permafrost and ground ice have developed in the lake basin since drainage in 1978. The lake bed soils are predominantly silts of varying moisture and organic-matter contents, with sandier soils near the lake margins. Excess-ice contents in the basin were also variable, and ice enrichment was observed to a maximum depth of 60 cm below the 2010 permafrost table. Shrub-covered, wet areas had the highest mean excess-ice content in the top 50 cm of permafrost (10%), while grassy, dryer areas (4%) and poorly vegetated marginal areas (<1%) were less enriched with ice. Site wetness was the most important variable associated with near-surface excess-ice content in the lake basin. Silt content was a secondary variable. Mean excess-ice content in the top 50 cm of permafrost at tundra sites (25%) was much greater than in the basin, with ice enrichment to greater depths, likely a result of the time available for permafrost aggradation since the early Holocene climatic optimum.
13029685 Song Changchun (Chinese Academy of Sciences, Northeast Institute of Geography and Agroecology, Changchun, China); Xu, Xiaofeng; Sun Xiaoxin; Tian, Hanqin; Sun Li; Miao Yuqing; Wang Xianwei and Guo Yuedong. Large methane emission upon spring thaw from natural wetlands in the northern permafrost region: Environmental Research Letters, 7(3), Citation 034009, illus. incl. 2 tables, sketch map, 39 ref., September 2012.
The permafrost carbon-climate feedback is one of the major mechanisms in controlling the climate-ecosystem interactions in northern high latitudes. Of this feedback, methane (CH4) emission from natural wetlands is critically important due to its high warming potential. The freeze-thaw transition has been confirmed to play an important role in annual CH4 budget, yet the magnitude of this effect is uncertain. An intensive field campaign was carried out in the Sanjiang Plain, Northeast China to estimate the CH4 emission in the spring freeze-thaw transition period. The observation concluded that a large CH4 source was caused by spring thaw; the maximum hourly emission rate was 48.6 g C m-2 h-1, more than three orders of the regularly observed CH4 emission rate in the growing season. In some sporadically observed 'hot spots', the spring thawing effect contributed to a large CH4 source of 31.3± 10.1 g C m-2, which is approximately 80% of the previously calculated annual CH4 emission in the same study area. If our results are typical for natural wetlands in the Northern Hemisphere permafrost region, we estimate a global CH4 source strength of 0.5-1.0 Tg C (1 Tg =1012 g) caused by spring thaw in the Northern Hemisphere permafrost region in the year 2011. Combining with available satellite and flask data, a regional extrapolation reaches a temporal pattern of CH4 emission during 2003-2009 which is consistent with recently observed changes in atmospheric CH4 concentration in the high latitudes. This suggests that the CH4 emission upon spring thaw in the high latitudes might be enhanced by the projected climate warming. These findings indicate that the spring thawing effect is an important mechanism in the permafrost carbon-climate feedback and needs to be incorporated in Earth system models. Copyright 2012 IOP Publishing Ltd
13027783 Zlotnikov, Dan. Mining in the extreme--Les mines aux extrêmes: CIM Magazine, 7(5), p. 50-61, (English, French), illus., August 2012.
13033324 Andreev, Andrei A. (Universität zu Köln, Institüt für Geologie und Mineralogie, Cologne, Germany); Morozova, E.; Fedorov, G.; Schirrmeister, L.; Bobrov, A. A.; Kienast, F. and Schwamborn, G. Vegetation history of central Chukotka deduced from permafrost paleoenvironmental records of the El'gygytgyn impact crater: Climate of the Past, 8(4), p. 1287-1300, illus. incl. 2 tables, sketch map, 55 ref., 2012. Part of special issue no. 48, Initial results from lake El'gygytgyn, western Beringia; first time-continuous Pliocene-Pleistocene terrestrial record from the Arctic, edited by Brigham-Grette, J., et al., URL: http://www.clim-past.net/special_issue48.html; published in Climate of the Past Discussion: 20 April 2012, URL: http://www.clim-past-discuss.net/8/1409/2012/cpd-8-1409-2012.html; accessed in Dec., 2012.
Frozen sediments from three cores bored in the permafrost surrounding the El'gygytgyn Impact Crater Lake have been studied for pollen, non-pollen palynomorphs, plant macrofossils and rhizopods. The palynological study of these cores contributes to a higher resolution of time intervals presented in a poor temporal resolution in the lacustrine sediments; namely the Allerod and succeeding periods. Moreover, the permafrost records better reflect local environmental changes, allowing a more reliable reconstruction of the local paleoenvironments. The new data confirm that shrub tundra with dwarf birch, shrub alder and willow dominated the lake surroundings during the Allerod warming. Younger Dryas pollen assemblages reflect abrupt changes to grass-sedge-herb dominated environments reflecting significantly drier and cooler climate. Low shrub tundra with dwarf birch and willow dominate the lake vicinity at the onset of the Holocene. The find of larch seeds indicate its local presence around 11 000 cal yr BP and, thus a northward shift of treeline by about 100 km during the early Holocene thermal optimum. Forest tundra with larch and shrub alder stands grew in the area during the early Holocene. After ca. 3500 cal yr BP similar-to-modern plant communities became common in the lake vicinity.
13033219 Jung, Jong-Won (Lawrence Berkeley National Laboratory, Berkeley, CA); Santamarina, J. Carlos and Soga, K. Stress-strain response of hydrate-bearing sands; numerical study using discrete element method simulations: Journal of Geophysical Research, 117(B4), Citation B04202, illus. incl. 1 table, 45 ref., 2012.
Gas hydrate is a crystalline solid found within marine and subpermafrost sediments. While the presence of hydrates can have a profound effect on sediment properties, the stress-strain behavior of hydrate-bearing sediments is poorly understood due to inherent limitations in laboratory testing. In this study, we use numerical simulations to improve our understanding of the mechanical behavior of hydrate-bearing sands. The hydrate mass is simulated as either small randomly distributed bonded grains or as "ripened hydrate" forming patchy saturation, whereby sediment clusters with 100% pore-filled hydrate saturation are distributed within a hydrate-free sediment. Simulation results reveal that reduced sand porosity and higher hydrate saturation cause an increase in stiffness, strength, and dilative tendency, and the critical state line shifts toward higher void ratio and higher shear strength. In particular, the critical state friction angle increases in sands with patchy saturation, while the apparent cohesion is affected the most when the hydrate mass is distributed in pores. Sediments with patchy hydrate distribution exhibit a slightly lower strength than sediments with randomly distributed hydrate. Finally, hydrate dissociation under drained conditions leads to volume contraction and/or stress relaxation, and pronounced shear strains can develop if the hydrate-bearing sand is subjected to deviatoric loading during dissociation.
13033319 Melton, Joe R. (University of Victoria, School of Earth and Ocean Sciences, Victoria, BC, Canada); Schaefer, H. and Whiticar, M. J. Enrichment in 13C of atmospheric CH4 during the Younger Dryas termination: Climate of the Past, 8(4), p. 1177-1197, illus. incl. 4 tables, 98 ref., 2012. Includes supplement, URL: http://www.clim-past.net/8/1177/2012/cp-8-1177-2012-supplement.pdf; published in Climate of the Past Discussion: 12 October 2011, URL: http://www.clim-past-discuss.net/7/3287/2011/cpd-7-3287-2011.html; accessed in Dec., 2012.
The abrupt warming across the Younger Dryas termination (~11 600 yr before present) was marked by a large increase in the global atmospheric methane mixing ratio. The debate over sources responsible for the rise in methane centers on the roles of global wetlands, marine gas hydrates, and thermokarst lakes. We present a new, higher-precision methane stable carbon isotope ratio (d13CH4) dataset from ice sampled at Pakitsoq, Greenland that shows distinct 13C-enrichment associated with this rise. We investigate the validity of this finding in face of known anomalous methane concentrations that occur at Pakitsoq. Comparison with previously published datasets to determine the robustness of our results indicates a similar trend in ice from both an Antarctic ice core and previously published Pakitsoq data measured using four different extraction and analytical techniques. The d13CH4 trend suggests that 13C-enriched CH4 sources played an important role in the concentration increase. In a first attempt at quantifying the various contributions from our data, we apply a methane triple mass balance of stable carbon and hydrogen isotope ratios and radiocarbon. The mass balance results suggest biomass burning (42-66% of total methane flux increase) and thermokarst lakes (27-59%) as the dominant contributing sources. Given the high uncertainty and low temporal resolution of the 14CH4 dataset used in the triple mass balance, we also performed a mass balance test using just d13C and dD. These results further support biomass burning as a dominant source, but do not allow distinguishing of thermokarst lake contributions from boreal wetlands, aerobic plant methane, or termites. Our results in both mass balance tests do not suggest as large a role for tropical wetlands or marine gas hydrates as commonly proposed.
13030951 Trofimova, I. E. (Rossiyskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Geografii, Irkutsk, Russian Federation) and Shekhovtsov, A. I. Otsenka termicheskogo rezhima pochv kotlovin Pribaykal'ya i severnogo Zabaykal'ya [Thermal regime of soils in depressions of the Baikal region and northern Transbaikalia]: Geografiya i Prirodnyye Resursy, 2011(4), p. 100-107 (English sum.), illus. incl. sketch map, 16 ref., December 2011.
Long-term data from meteorological stations have been used in assessing the thermal state of the soil layer in large depressions of Prebaikalia and Northern Transbaikalia. The characteristics of temperature distribution in depth over a yearly cycle for seasonally freezing and permafrost soils were examined. For the baikalian-type depressions, spatial differentiation of the lowest and highest (with regard to the temperature lag with depth) monthly averaged soil temperatures was carried out. It is concluded that within a single depression the thermal regime of the soil fluctuates over a very broad range. On the other hand, an identical situation with the temperature regime can occur in different depressions.
13030012 Behl, Richard J. (California State University, Department of Geological Sciences, Long Beach, CA). Glacial demise and methane's rise: Proceedings of the National Academy of Sciences of the United States of America, 108(15), p. 5925-5926, illus., 23 ref., April 12, 2011. For reference to original see Reyes, A. V. and Cook, C. A., 2011, Proceedings of the National Academy of Sciences of the United States of America Journal, Vol. 108, No. 12, p. 4748-4753, DOI: 10.1073/pnas.1013270108.
13029473 Broll, Gabriele. Folgen des Klimawandels für terrestrische Okosysteme der Arktis und Subarktis [Consequences of climate change for terrestrial ecosystems of the Arctic and subarctic]: Geographische Rundschau, 63(12), p. 20-25, 33 ref., 2011.
13033092 Lindroos, Antti-Jussi (Finnish Forest Research Institute, Vantaa, Finland); Derome, John; Derome, Kirsti and Smolander, Aino. The effect of Scots pine, Norway spruce and silver birch on the chemical composition of stand throughfall and upper soil percolation water in northern Finland: Boreal Environment Research, 16(3), p. 240-250, illus. incl. 2 tables, 36 ref., 2011. Accessed on April 5, 2013.
13034342 Bittelli, Marco (University of Bologna, Department of AgroEnvironmental Science and Technology, Bologna, Italy); Tomei, Fausto; Pistocchi, Alberto; Flury, Markus; Boll, Jan; Brooks, Erin S. and Antolini, Gabriele. Development and testing of a physically based, three-dimensional model of surface and subsurface hydrology: Advances in Water Resources, 33(1), p. 106-122, illus. incl. 2 tables, geol. sketch map, 61 ref., January 2010.
We present a numerical, catchment-scale model that solves flow equations of surface and subsurface flow in a three-dimensional domain. Surface flow is described by the two-dimensional parabolic approximation of the St. Venant equation, using Manning's equation of motion; subsurface flow is described by the three-dimensional Richards' equation for the unsaturated zone and by three-dimensional Darcy's law for the saturated zone, using an integrated finite difference formulation. The hydrological component is a dynamic link library implemented within a comprehensive model which simulates surface energy, radiation budget, snow melt, potential evapotranspiration, plant development and plant water uptake. We tested the model by comparing distributed and integrated three-dimensional simulated and observed perched water depth (PWD), stream flow data, and soil water contents for a small catchment. Additional tests were performed for the snow melting algorithm as well as the different hydrological processes involved. The model successfully described the water balance and its components as evidenced by good agreement between measured and modelled data. Abstract Copyright (2010) Elsevier, B.V.
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13033686 Karunaratne, Kumari Catharine. A field examination of climate-permafrost relations in continuous and discontinuous permafrost of the Slave geological province: 255 p., Doctoral, 2011, Carleton University, Ottawa, ON, Canada. ISBN: 978-0-494-81573-1 Available from: Univ. Microfilms.
13033702 Mohanty, Sanjay. Colloid-facilitated transport of cations in an unsaturated fractured soil under transient condition: 226 p., Doctoral, 2011, University of Colorado at Boulder, Boulder, CO. ISBN: 978-1-267-00894-9 Available from: Univ. Microfilms.
13030673 Panda, Santosh K. Permafrost distribution mapping and temperature modeling along the Alaska highway corridor, interior Alaska: 140 p., Doctoral, 2011, University of Alaska at Fairbanks, Fairbanks, AK. ISBN: 978-1-267-18951-6 Available from: Univ. Micorfilms, Ann Arbor, MI, United States.
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13031664 Wenske, Dirk (Freie Universität Berlin, Institute of Geographical Sciences, Berlin, Germany); Frechen, Manfred; Böse, Margot; Reimann, Tony; Tseng, Chia-Han and Hoelzmann, Philipp. Late Quaternary river terraces in the Central Mountain Range of Taiwan; a study of cover sediments across a terrace section along the Tachia River: in Late Quaternary morphodynamics in east Asia (Böse, Margot, editor), Quaternary International, 263, p. 26-36, illus. incl. strat. cols., sect., 6 tables, geol. sketch maps, 64 ref., June 14, 2012. Meeting: European Geosciences Union general assembly 2010; session on Late Quaternary morphodynamis in east Asia, May 2-7, 2010, Vienna, Austria.
The existence of fluvial terraces in the high mountains of Taiwan has been known for a long time already, but these terraces have not yet been studied in detail. This paper studies cover sediments across a terrace section in the Central Mountain Range located at the midstream reaches of the Tachia River at an elevation of 1430 m asl. Sediments were dated by means of optically stimulated luminescence and radiocarbon dating, yielding robust ages between 54.8±7.0 ka and 0.42±0.09 cal. ka BP. These dates are in good agreement with ages known for the laterite terraces (LT) in the mountain foreland. Deeply weathered reddish soils, comparable to those in the mountain forelands, are absent. Hence, in stratigraphic terms, the terraces in the high mountains cannot be correlated with those in the mountain foreland. Cover sediments comprise eolian sand and silt and various colluvial layers. Eolian sediments provide paleoenvironmental evidence of a relatively dry phase in early MIS 3 that coincides with the maximum extent of the glaciations in the Hsueh Shan Mountain area. Widespread colluvial sediments indicate a high frequency of mass movements around 38.5 ka, a period of time known to correlate with dominantly wet conditions. In the last 1000 years, wildfire appears as a possible trigger of mass movements. The geochronological data indicate a local bedrock strath incision rate of 0.8±0.1 mm y-1, a value that appears to be in agreement with the local decadal scale erosion rate. Abstract Copyright (2012) Elsevier, B.V.
13031639 Fisher, Daniel C. (University of Michigan, Museum of Paleontology, Ann Arbor, MI); Tikhonov, Alexei N.; Kosintsev, Pavel A.; Rountrey, Adam N.; Buigues, Bernard and van der Plicht, Johannes. Anatomy, death, and preservation of a woolly mammoth (Mammuthus primigenius) calf, Yamal Peninsula, northwest Siberia: in Mammoths and their relatives; 1, Biotopes, evolution and human impact V international conference, Le Puy-en-Velay, 2010 (Lacombat, Frédéric, editor; et al.), Quaternary International, 255, p. 94-105, illus. incl. 1 table, 28 ref., March 26, 2012. Meeting: 5th international conference on Mammoths and their relatives from the Pliocene to present-day, Aug. 30-Sept. 4, 2010, Le Puy-en-Velay, France.
A well-preserved woolly mammoth calf found in northwest Siberia offers unique opportunities to investigate mammoth anatomy, behavior, life history and taphonomy. Analysis of the fluvial setting where the specimen was found suggests it was derived from eroding bluffs during ice-out flooding in June 2006. It then lay exposed on a point-bar surface until recovery the following May. AMS dating of bone collagen and plant tissues from the intestine provide age estimates that average about 41,800 14C yrBP. Anatomical features of interest include a hemispherical mass, apparently composed of brown fat, on the back of the neck. This may have functioned in thermoregulation for the neonate mammoth, born before onset of spring. Abundant subcutaneous fat and milk residues in the alimentary tract demonstrate that this animal was in good nutritional condition before death, making other features of its life history relevant for general studies of mammoth paleobiology. Plant remains from the intestine (mixed with milk residue in a manner consistent with frequent, small meals) show evidence of mastication by adult mammoths, suggesting that this calf ingested fecal material, probably from its mother and presumably to inoculate its intestinal tract with a microbial assemblage derived from a healthy adult. Discrepancies between the season of death we infer (spring) and seasonal indicators from the intestine implicate coprophagy (involving old fecal boli) by the mother. This animal's trachea and bronchi are completely occluded with fine-grained vivianite (hydrated iron phosphate) such as occurs in some lacustrine settings. Because this vivianite does not penetrate the lung beyond the bronchi, we infer that it must have entered as a viscous mass that occluded the airway, causing asphyxia. Nodular vivianite in the cranial region and interiors of long bones must have originated postmortem, but its distribution may be partly controlled by peripheral vasoconstriction, a physiological response to asphyxia. Nodular vivianite may have formed from iron derived from hemoglobin and phosphate liberated by partial demineralization of bones. Demineralization could have been caused by lactic acid, for which the main evidence is loss of tissues dominated by Type 1 collagen (denatured in lactic acid). We propose that this was consequent on postmortem colonization of the body by lactic acid-producing bacteria. These bacteria and their metabolites may have promoted preservation during the time before the body was incorporated in permafrost and could also have inhibited scavenging and bacterial decomposition following recent exposure of the specimen.
13031644 Neustroev, M. P. (Russian Academy of Agricultural Sciences, Yakut Scientific Research Institute of Agriculture, Yakutsk, Russian Federation). On the prospects of microbiological research on mammoth fauna in permafrost: in Mammoths and their relatives; 1, Biotopes, evolution and human impact V international conference, Le Puy-en-Velay, 2010 (Lacombat, Frédéric, editor; et al.), Quaternary International, 255, p. 139-140, March 26, 2012. Meeting: 5th international conference on Mammoths and their relatives from the Pliocene to present-day, Aug. 30-Sept. 4, 2010, Le Puy-en-Velay, France.
Research of mammoth microflora is of current interest in terms of psychrophiles, cryoanabiosis, and the peculiar properties of ecology and evolution of microorganisms. Recovered Bacillus bacteria strains of the mammoths express antagonistic activity against pathogenic and opportunistic microorganisms. Moreover, the strains are antibiotic resistant and salt tolerant. The obtained data is consistent with research on biocoenosis of domestic and wild animals, cryogenic soil, air, atmosphere precipitation, and plants. Having high biological activity, Bacillus bacteria are the dominant group in the microbiocenosis environment in permafrost.
13028190 Colgan, Patrick M. (Grand Valley State University, Department of Geology, Allendale, MI) and Zdan, Steve. Sedimentary origin and geotechnical properties of subglacial till, Ottawa County, Michigan [abstr.]: in abstracts of papers presented; Annual meetings of the Michigan Academy, Michigan Academician, 40(3), p. 264, 2012. Meeting: Annual meetings of the Michigan Academy, March 26, 2010, Grand Rapids, MI.
13028182 Daniels, Stacy L. (University of Michigan, Department of Chemical Engineering, Ann Arbor, MI); Long, David T. and Yohn, Sharon J. The "tragedy" of Crystal Lake; confirmed by sediment geochronology and soil survey [abstr.]: in abstracts of papers presented; Annual meetings of the Michigan Academy, Michigan Academician, 40(3), p. 260, 2012. Meeting: Annual meetings of the Michigan Academy, March 26, 2010, Grand Rapids, MI.
13033339 Drozdov, Alexander (Institute "Yakutniproalmaz" "ALROSA", Mirny, Russian Federation) and Popov, Vladimir. Evolution of cryohydrosphere near diamond deposits of western Yakutia [abstr.]: in 34th international geological congress; abstracts, International Geological Congress, Abstracts = Congrès Géologique International, Résumés, 34, p. 3610, 2012. compact disc. Meeting: 34th international geological congress, Aug. 5-10, 2012, Brisbane, Queensl., Australia. Accessed on Feb. 22, 2013.
Underground cryohydrosphere of Yakutian diamondiferous province is related to the East-Siberian artesian area and is subjected to powerful anthropogenic effect from long-term operation of deposits Mir, International, Udachnaya and others. Sections of sub-permafrost water-bearing complex, isolated from influence of surface factors and confined to the zones of regional tectonic dislocations near trappean intrusions, are optimum hydro-geological structures for reclaiming liquid waste in the south of the diamondiferous province. Over 200 million m3 of water have been pumped out and removed back into the drainable water-bearing complex in the southern part of the region during dewatering of open pit Mir since 1977. In recent years complicated piezometric surface of levels with clearly expressed repressuring dome from reinjection of drainage water and depressuring cone from dewatering in open pit Mir has been formed. Mining of diamondiferous deposits in conditions of water influx in the north of Western Yakutia, in particular on the largest pipe Udachnaya, has been carried out since 1985. At present 10,7 million m3 of drainage brines have been removed.
13034773 Kulkova, Marianna (Herzen Pedagogical University, St. Petersburg, Russian Federation); Nesterov, Evgeny and Lebedev, Sergey. Radiocarbon in the ecosystem of Baltic Sea basin (Russian Federation) [abstr.]: in 34th international geological congress; abstracts, International Geological Congress, Abstracts = Congrès Géologique International, Résumés, 34, p. 3264, 2012. compact disc. Meeting: 34th international geological congress, Aug. 5-10, 2012, Brisbane, Queensl., Australia.
The expanding construction of nuclear industrial plants and nuclear power stations on the shores of the Baltic Sea (near St. Petersburg, Russia) is creating a real possibility for the introduction of long-life radioactive isotope of carbon into the vegetation, soils and water of Baltic Sea basin ecosystem. A 307 Sample Oxidizer and low-level liquid scintillation counting Quantulus 1220 (Wallac) were applied for determination of radiocarbon activity in this region. Significant difference was observed on the distribution of radiocarbon concentrations in different types of objects of Baltic Sea basin ecosystem. The distribution of radiocarbon in the tree-rings of wood near Nuclear Power Plant at Sosnovy Bor allows to register the time of high radiocarbon activity in an atmosphere for last 150 years and to determine the local and regional sources of radiocarbon emission. GIS maps of radiocarbon distribution for different types of objects of Baltic Sea basin ecosystem were constructed. Such approach gives the possibility to reveal the entrance of radioisotope in environment on the initial stage of pollution and to control their diffusion. The researchers are supported by project FCP N 1156 (The scientific and scientific-pedagogical specialists of innovation Russia, 2009-2013).
13034794 Nesterov, Evgeny (Herzen University, Department of Geology and Geoecology, Russian Federation); Kulkova, Marianna; Egorov, Pavel and Morozov, Dmitri. The reconstruction of environment during Holocene in the coastal zone of Gulf of Finland (Russia) [abstr.]: in 34th international geological congress; abstracts, International Geological Congress, Abstracts = Congrès Géologique International, Résumés, 34, p. 3285, 2012. compact disc. Meeting: 34th international geological congress, Aug. 5-10, 2012, Brisbane, Queensl., Australia.
The study of sediments in the Lakes located on the coastal zone of Gulf of Finland during Holocene gives the possibility to consider the stages of coastal zone development, the transgression and regression in the Baltic Sea and their influence on the composition of bottom sediments. On the base of detail geochemical analysis and radiocarbon dating of bottom deposits the influence of environmental and anthropogenic factors on the character of lake sedimentation was determined. The variations of geochemical modules reflect the changes in landscape-climatic conditions and their influence on the sediment composition. The lake sediments as the most conservative component of water system are the good markers of anthropogenic impact too. The data obtained allowed us to supplement and extend the current conceptualization about evolution of coastal zone of Gulf of Finland. The geochemical data of anthropogenic deposits of Neolithic-Early Metal Ages on this territory is considered too. The character of distribution and analysis of some geochemical components -- indicators of anthropogenic connected with domestic activity of prehistoric people on the surface archaeological site allowed us to determine the different functional zones -- locations of ancient occupation. These investigations are important for geochemical reconstruction of thy Environment History and it is necessary in the ecological assessment of using of natural resources and coherent evolution of sediment and soil systems.
13031521 Dirksen, O. (Russian Academy of Sciences, Institute of Volcanology and Seismology, Petropavlovsk-Kamchatsky, Russian Federation); van den Bogaard, C.; Danhara, Tohru and Diekmann, B. Tephrochronological investigation at Dvuh-Yurtochnoe Lake area, Kamchatka; numerous landslides and lake tsunami, and their environmental impacts: in Enhancing tephrochronology and its application (INTREPID Project); Hiroshi Machida commemorative volume (Lowe, David J., editor; et al.), Quaternary International, 246(1-2), p. 298-311, illus. incl. sects., 3 tables, geol. sketch maps, 35 ref., December 20, 2011. Meeting: Active tephra in Kyushu 2010; international field conference on Tephrochronology, volcanism, and human activity, May 9-17, 2010, Kirishima, Japan.
Distal volcanic tephras in soil sections and lake sediments in the Dvuh-yurtochnoe (Two-Yurts) lake area, central Kamchatka, were investigated in order to provide a chronological framework for the reconstruction of late Quaternary landscape development. Mineralogical and geochemical data point to sources from 5 volcanoes. Ten tephra layers were identified and correlated to known eruptive events. The ages were corroborated by radiocarbon dating of the soil sections around Two-Yurts lake. These findings allow the reconstruction of regional paleoenvironmental change, recorded in the soil sections around Two-Yurts lake. During the Last Glacial Maximum (LGM) time, the area was affected by glacial advances that produced the glacial moraines at the eastern outlet of the lake. A large landslide, ca. 15,000-18,000 14C BP, dammed the valley and led to formation of Two-Yurts lake. Several more landslide events can be recognized in the Holocene, and one affected Two-Yurts lake ca. 3000 14C BP. This event produced a "tsunami", documented by poorly sorted deposits with rounded pebbles in the onshore sections around the lake. In contrast to the soil sections, tephras buried in the "soupy" lacustrine sediments of Two-Yurts lake are not well preserved and show inconsistent age-depth relationships compared to those suggested by radiocarbon dating, due to sinking through the lake sediments. Nevertheless, tephrochronological data revealed the strong impact of terrestrial landslides on lake sedimentation.
13031523 Watt, Sebastian F. L. (University of Oxford, Department of Earth Sciences, Oxford, United Kingdom); Pyle, David M.; Naranjo, José Antonio; Rosqvist, Gunhild; Mella, Mauricio; Mather, Tamsin A. and Moreno, Hugo. Holocene tephrochronology of the Hualaihue region (Andean southern volcanic zone, ~42° S), southern Chile: in Enhancing tephrochronology and its application (INTREPID Project); Hiroshi Machida commemorative volume (Lowe, David J., editor; et al.), Quaternary International, 246(1-2), p. 324-343, illus. incl. sects., 5 tables, geol. sketch maps, 57 ref., December 20, 2011. Meeting: Active tephra in Kyushu 2010; international field conference on Tephrochronology, volcanism, and human activity, May 9-17, 2010, Kirishima, Japan.
Late Glacial and Holocene soils and sediments in southern Chile contain an important record of explosive volcanic activity since the end of the last glaciation, and have considerable potential for the development of a regional tephrostratigraphical framework. This paper reports the discovery of several new tephra deposits from the Hualaihue region (~42° S) of southern Chile. Eruption sizes, constrained from field observations, and ages, constrained by 25 new radiocarbon dates, show that the volcanoes of the Hualaihue peninsula have had relatively few explosive, tephra-generating eruptions during the Holocene. An eruption of Apagado deposited ~1 km3 of bedded basaltic scoria at ~2.6 calibrated (cal) ka BP, and Hornopiren produced a similar, but volumetrically-smaller unit at ~5.7 cal ka BP. Activity at Yate over the same time period has been predominantly characterised by lava production, although small explosive eruptions, the products of which span a range of compositions, have also occurred, including one at ~0.9 cal ka BP. The northern part of the regional tephra sequence is dominated by andesitic pumice fall deposits derived from Calbuco volcano. These include deposits from several eruptions during a 3500-year-long period at the start of the Holocene, as well as two large explosive eruptions in the past 2000 years. A distinctive rhyolitic tephra layer that is interbedded with the locally derived tephra sequence is the Cha1 unit, from Chaiten volcano, 108 km south of Hornopiren. This rhyolitic pumice deposit, dated at ~9.75 cal ka BP, is the largest volumetrically of those described here, with a volume of 3.5 km3. This new tephrostratigraphy covers a region whose volcanic history was previously very little known, and contributes to a regional record of large explosive eruptions that now spans a 500 km-long segment of the southern Andean arc, between Calbuco and Hudson volcanoes.
13031483 Blender, Richard (Universität Hamburg, Meteorologisches Institut, Hamburg, Germany); Zhu, Xiuhua; Zhang, Dan and Fraedrich, Klaus. Yangtze runoff, precipitation, and the East Asian monsoon in a 2800 years climate control simulation: in Larger Asian rivers; climate, hydrology and ecosystems (Tong Jiang, editor; et al.), Quaternary International, 244(2), p. 194-201, illus. incl. 3 tables, sketch map, 39 ref., November 15, 2011. Meeting: 10 years Sino-German Yangtze research cooperation parallel workshops, Oct. 24-30, 2009, Wuhan, China.
Variability of the Yangtze catchment hydrology is closely linked with the Tibetan Plateau snow cover and the large scale atmospheric circulation in East Asia. These connections are analyzed in a control simulation (2800 years) of the atmosphere-ocean general circulation model (ECHAM5/MPIOM) coupled to vegetation and ocean biogeochemistry modules. (i) Up to decades in time scale, runoff, soil wetness, and temperature show long term memory (LTM) with an intradecadal scaling of the power spectrum with the exponent b » 0.6, while precipitation, snow depth, and snow melt reveal no memory. (ii) Multi-decadal variability of runoff, soil wetness, and temperature shows weak LTM similar to snow depth and melt on the Tibetan Plateau. (iii) On the annual time scale, the atmospheric circulation impact of Hadley cell and ENSO on precipitation, temperature and snow melt are weak but significant; on decadal time scales the subtropical monsoon modulates the catchment hydrology. Temperature is anticorrelated with precipitation and soil wetness in the Yangtze catchment. Singular spectrum analysis highlights the 3-4 year ENSO mode in the monsoon indices, precipitation, and snow depth, explaining their high correlations. Projecting snow depth on ENSO shows long term variations explaining conflicting results obtained from correlations in short data sets. Abstract Copyright (2011) Elsevier, B.V.
13031481 Liu Jingshi (Chinese Academy of Sciences, Institute of Tibetan Plateau Research, Beijing, China); Xie Jian; Gong Tongliang; Wang Hong and Xie Yuhong. Impacts of winter warming and permafrost degradation on water variability, upper Lhasa River, Tibet: in Larger Asian rivers; climate, hydrology and ecosystems (Tong Jiang, editor; et al.), Quaternary International, 244(2), p. 178-184, illus. incl. 2 tables, sketch maps, 27 ref., November 15, 2011. Meeting: 10 years Sino-German Yangtze research cooperation parallel workshops, Oct. 24-30, 2009, Wuhan, China.
Watersheds in frozen ground have been influenced by climate change for centuries, particularly in the last two decades when permafrost degradation has accelerated and intensified. This degradation speeds up water transfer, increases soil moisture, improves agricultural productivity, and affects the ecological environment. It is important to evaluate the effects of these impacts on hydrology to develop sustainable water resources management in cold regions. This study evaluated changes in both winter air temperature and streamflow regime for a selected drainage basin at low latitude but high altitude following large scale permafrost degradation in the Tibetan Plateau. The non-parametric Mann-Kendall test was used to identify trends in both winter air temperature and streamflow. The results showed significant upward trends in winter flow but not summer runoff. The trend tests indicated that change points of winter streamflow and temperature occurred in 1985 and 1983, respectively. Comparison of winter flow duration for two 16-year periods (1976-1991 and 1992-2008) showed a significantly upward trend in winter streamflow. Increases in most winter flows varied from 16% to 24%, while the increase in low flows was much greater. There were reliable positive correlations between the October and November temperatures and the following monthly discharges. Both the temperature rise and discharge increase at start of the frost period can greatly increase drainage of subsurface water in February, when the maximum variability occurred. The total increases in winter flow are increasing as a function of time, with significant changes occurring since the early 1980s. However, it is yet unclear if the watershed has seen the full effects of the permafrost degradation over the Tibetan Plateau. Abstract Copyright (2011) Elsevier, B.V.
13027265 Bellomo, Laura (University of Wisconsin-Madison, Department of Geography, Madison, WI); Hanson, Paul R.; Jennings, Carrie E. and Alexander, E. Calvin, Jr. Optically stimulated luminescence (OSL) dating of glacial sediment in Crystal Cave, WI [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 450, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
Until recently, the chronology of late Wisconsinan glaciation has been confined to radiocarbon dating organic material within glacial deposits, but some of these dates are considered unreliable due to possible contamination by older organic matter (Clayton 1982, Attig, 1985). Using optically stimulated luminescence (OSL) dating, samples of glacial sediment deposited in a cave system in western Wisconsin yielded optical ages that constrain the St. Croix-Hancock phase of the late Wisconsinan glaciation. This data shows active sediment deposition from around 24,000 B.P and places the maximum glacial extent of the St. Croix and Chippewa lobes between 20,000 B.P and 17,000 B.P. Previous studies of glacier bed conditions (Attig et al. 1989) and aerial photos of ice-wedge polygons (Clayton et al. 2001) suggest regional permafrost during this time period. This is supported by the presence of a thin layer of loess over the earlier cave sediment, indicating a possibly a halt in groundwater movement and glacial melt-water deposition. The consequences of this study show OSL can be an effective dating method not only for glacial outwash, but also for allochthonous cave sediment. It also constitutes as one of the first studies that provide chronological evidence for the late Wisconsinan glaciation by investigating sediment deposited within a periglacial karst environment.
13032805 Froese, Duane (University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada); Smith, Derald G. and Reyes, Alberto. The northwest outlet of glacial Lake Agassiz; a catastrophic flood, oil-contaminated radiocarbon dates and permafrost [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 348, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
The northwest outlet of glacial Lake Agassiz figures prominently into multiple versions of the drainage history of the lake with most interest focused on whether the opening of the NW outlet and associated catastrophic flood sediments were deposited near the start of the Younger Dryas chronozone (YD). We revisited stratigraphy of exposures along the Athabasca Valley associated with aggregate development for several oilsand extraction sites, and exposures along the lower Athabasca River. We recognize five units in the valley: (1) pre-Laurentide Athabasca River gravel deposited prior to advance of the Laurentide Ice Sheet; (2) post-glacial Athabasca river gravels; (3) catastrophic flood deposition associated with the Clearwater spillway; (4) sandy braided river sedimentation following flood deposition; and (5) fluvial-deltaic sedimentation in the lower Athabasca into glacial Lake McConnell. Radiocarbon ages on mammoth bones and wood suggest a mid-Wisconsinan age for unit 1. The surface of flood-related gravels are modified by periglacial structures, including ice wedge casts and involutions on the surface, suggesting that climate was sufficiently cold when the NW outlet was active to have active permafrost, presumably extending into the late Pleistocene. New radiocarbon ages on plant macrofossils and spruce logs within deltaic sediments in the lower Athabasca Valley show persistent impacts of bitumen contamination on many samples, which we removed using organic solvents in a soxhlet apparatus. Collectively the radiocarbon chronology together with the presence of periglacial structures on the surface of flood-related features suggest the NW outlet was active at least during part of YD time, but it is still unclear if flood initiation was coincident with the beginning of the YD.
13027320 Henning, Russell (AECOM, Green Bay, WI); Gotkowitz, Madeline B.; Goetz, Staci and Marciulionis, Jackie. Using GSFLOW to model groundwater flooding recurrence intervals [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 460, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
The Spring Green, Wisconsin area has been susceptible to flooding in the recent past in areas located outside the Federal Emergency Management Agency Digital Flood Insurance Rate Mapped areas for the Wisconsin River. The flooding has not been the result of the Wisconsin River overflowing its banks, but rather has resulted from saturated soils, groundwater inundation, and overland flow runoff during periods of heavy snowpack melt and rainfall. On June 7 and 8, 2008, heavy rains fell on snowmelt-saturated soils in Southern Wisconsin, causing historic flooding that inundated almost 7 square miles of the Spring Green area with standing water for five months and caused contamination to water supply wells, agricultural crop loss, and damage to homes, buildings, and infrastructure. Surface water-groundwater interactions were modeled using GSFLOW, a coupled model developed by the United States Geological Survey, to recreate the June 2008 groundwater inundation flood event for the purpose of calculating recurrence intervals for this and other historical flood events. The coupled model used historical precipitation, landuse, soils, vegetative canopy, and other climate data to predict surface water runoff and groundwater elevations. Measured climatic data spanning forty years was used to model precipitation, infiltration and runoff using the PRMS portion of GSFLOW. Groundwater was modeled using a modified version of the Wisconsin Geological and Natural History Survey Sauk County MODFLOW model. Modeled groundwater heads at observation points typically predicted the 2008 flood event as the largest magnitude groundwater event during the 40-year model period and the magnitude of head change was similar to regional groundwater observation well records. Predicted areas of shallow groundwater also generally coincided to the field-mapped areas of shallow groundwater indicators. This approach could be used to assess other large areas susceptible to groundwater inundation flooding.
13027269 Konen, Michael (Northern Illinois University, DeKalb, IL); Indorante, Samuel; Follmer, Leon and Gerhard, Erik. Landscape evolution and modern soil geomorphic relationships associated with patterned ground in south central Illinois [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 451, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
Recent mapping of high pH, sodium affected soils (SAS) in south central Illinois has revealed the occurrence of extensive networks of polygonal patterned ground (PPG) associated with SAS. SAS occupy approximately 383,512 ha of the Springfield Plain and occur on extremely low-relief, planar landscapes where 1-2 m of Wisconsin Episode loess overlies a lower permeability Sangamon Geosol developed in Illinois Episode glacigenic sediments. SAS associated polygons are typically 10 to 80 m in diameter with 4 to 6 m borders. Polygon interiors are darker colored with lighter colored borders and referred to as "reverse patterned ground". PPG occurring on the Bloomington Ridged Plain in northern and central Illinois in Wisconsin Episode glacigenic diamictons and Peoria Silt have the same dimensions but have darker colored borders surrounding lighter colored interiors. The SAS related PPG on the Springfield Plain is interpreted to have formed as a result of Wisconsin Episode permafrost formation and degradation. We will focus our discussion on the geomorphic significance of permafrost related processes and how they have led to a unique microtopography that has in turn led to the post-glacial formation of SAS in south central Illinois. We also propose that the southern limit of Wisconsin Episode permafrost is farther south than previously mapped.
13031548 Loomis, Shannon E. (Brown University, Department of Geological Sciences, Providence, RI); Russell, James M.; Heureux, Ana and Sinninghe Damste, Jaap S. Lacustrine paleothermometry; seasonal variability of branched GDGTs in a temperate lake system [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 465, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
Quantitative paleoclimate reconstructions are necessary for testing the reliability of models that predict future climates; however, there are few proxies that can quantitatively reconstruct temperatures over much of the terrestrial realm. Recently, a continental paleothermometer has emerged that utilizes bacterial membrane lipids known as branched glycerol dialkyl glycerol tetraethers (GDGTs). Branched GDGTs are found in a variety of terrestrial environments, including peats, soils, and lake sediments, and the relative distribution of the nine different GDGTs responds to changes in the mean annual air temperature and pH of their environment. This demonstrates that branched GDGTs preserved in lake sediments have the potential to be used as a continental temperature proxy, but there is still debate over whether branched GDGTs in lake sediments are derived from the landscape or produced in situ. Furthermore, if in situ production is the main source, it is unclear whether it occurs within the water column or in the sediments themselves. To elucidate the origins of branched GDGTs in a temperate lake system, we collected sediment trap and water column samples on a biweekly to monthly basis for over two years at South King Pond, a small kettle lake near Montpellier, Vermont. These samples were analyzed for their branched GDGT distributions and abundances and compared to lake surface sediments and soil samples from the catchment. We find that branched GDGT distributions are fairly constant over the seasonal cycle and are very similar between the sediment trap, the water column, and the surface sediment transect. The branched GDGT distributions observed in lake samples are very different from those in the soil samples, indicating that GDGTs in the lakes are primarily produced in situ. Branched GDGT concentrations are much higher in the hypolimnion of the lake, suggesting that branched GDGTs are mainly produced in the anoxic bottom waters over much of the year. However, branched GDGTs fluxes to the sediment trap increase dramatically during the two seasonal mixing periods, especially during fall turnover, when the lake is fully oxygenated. As such, paleotemperature reconstructions utilizing the branched GDGT proxy are likely recording bottom water temperatures and/or lake mixing temperatures in dimictic systems.
13027268 Mason, Joseph A. (University of Wisconsin-Madison, Department of Geography, Madison, WI); Jacobs, Peter M.; Hanson, Paul R.; Stanley, Kristine E.; Loope, Henry M. and Young, Aaron R. Late Quaternary eolian and hillslope processes and the distribution of xeric plant communities in the Upper Mississippi Valley [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 451, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
The legacy of late Quaternary paleoenvironments in the modern landscape of the Upper Mississippi Valley is a recurrent theme in the research of Jim Knox and his students. The effects of Late Pleistocene eolian and hillslope processes are especially evident in the loess and colluvium that mantle much of the UMV outside late Pleistocene glacial limits. A more subtle legacy involves patches of the landscape where loess is absent or is mixed with sand or rock fragments, diluting its capacity for moisture and nutrient retention. These patches were often the setting for distinctive xeric, fire-dependent plant communities, preserved to varying degrees in the modern landscape. In river valleys of southeastern Minnesota and along the Upper Mississippi in northwestern Illinois, late Pleistocene eolian sand formed ramps climbing to adjacent ridgetops, usually at locations where there is a long down- or cross-valley fetch for westerly or northwesterly winds. At these sites, weakly developed sandy soils, with much lower capacity for moisture and nutrient retention than well-developed Alfisols in adjacent loess-mantled areas, hosted a variety of distinctive sand barrens and other xeric plant communities. At a very different spatial scale, the extensive areas of xeric vegetation in west-central Wisconsin are at least in part related to widespread eolian sand transport and the resulting lack of loess cover. Hillslope processes also influenced the vegetation mosaic in the bedrock-controlled landscape of southeastern Minnesota. Steep upper slopes are mantled by sheets of blocky colluvium with a loess-derived matrix that developed mainly in the late Pleistocene. Where this colluvial mantle extends downslope over Cambrian sandstone, it is thin or absent and soils are often formed partly or completely in weathered sandstone or sandy hillslope sediment. Field measurements indicate that soil moisture is more rapidly depleted in this zone of sandstone-influenced soils than in thick loess or silt-rich colluvium, potentially favoring xeric vegetation. "Goat prairies" are still present today on some south-facing slopes with a thin patchy colluvial mantle over sandstone, and a variety of evidence including carbon isotopes in soil organic matter suggests that open oak savanna was common in this geomorphic setting in the past.
13033029 McClymont, Alastair F. (University of Calgary, Department of Geoscience, Calgary, AB, Canada); Hayashi, Masaki and Bentley, L. R. Subsurface thaw of discontinuous permafrost in northwestern Canada; evidence from geophysical imaging and thermal conduction modeling [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 389, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
Some of the most pronounced climate warming of recent times has been occurring in northwestern Canada, resulting in widespread permafrost thaw. Since permafrost within discontinuous permafrost zones has subsurface temperatures close to 0°C, small changes in the surface energy balance, resulting from rises in air temperature or landcover changes, can cause significant degradation of permafrost in the subsurface. By using electrical resistivity tomography (ERT), ground-penetrating radar (GPR) and thermal conduction modeling, we show how subsurface energy-transfer processes influence thawing of discontinuous permafrost in the wetland-dominated peatlands of the Hay River Lowland ecoregion of Canada. In this environment the permafrost bodies have thicknesses of ca. 10 m and occur under tree-covered peat plateaus that are elevated by 0.5-2 m from the local water table. By using interpretations of our ERT profiles, we show how disturbances within the active layer promote enhanced sites of long-term thaw in the underlying permafrost. In order to investigate how contemporary climatic conditions and landcover disturbances will influence future changes to the subsurface permafrost distribution, we construct two-dimensional thermal conduction models using constraints derived from one of our geophysics profiles and observed soil temperature data. Results show that thermal energy input is higher under permafrost-free bogs and channel fens than it is under the peat plateaus and that thaw-induced subsidence and flooding at the lateral margins of peat plateaus induces enhanced vertical energy transfer along the margins of peat plateaus. As a consequence of these processes the permafrost bodies are thawing faster laterally than they are vertically.
13034485 Wang Liqiang (Chinese Academy of Sciences, Key Laboratory of Tibetan Environmental Changes and Land Surface Processes, Beijing, China) and Yi Chaolu. Properties and periglacial processes in alpine meadow soils, western Nyainqentanglha Mountains, Tibet: in Quaternary paleoenvironmental change and landscape development in Tibet and the bordering mountains (Yi Chaolu, editor; et al.), Quaternary International, 236(1-2), p. 65-74, illus. incl. 1 table, sketch map, 25 ref., May 1, 2011. Meeting: 5th international symposium on Tibetan Plateau, Aug. 11-14, 2009, Beijing, China.
One hundred and three samples were collected from nine soil profiles in alpine meadows on glacial moraines in two valleys on the northwestern slope of the West Nyainqentanglha Mountains, central Tibet. Properties measured were soil organic carbon (SOC), soil organic matter (SOM), principal anions and cations, total nitrogen, available nitrogen, pH, water content and grain size. High concentrations of SO42-, HCO3- and Cl- and lack of CO32- are consistent with the acidity of the soil: pH < 6.21. Na+ and K+ are concentrated at depths of 0.2-0.4 m. A high concentration of Ca2+ in the profiles indicates that leaching is weak. Sand and pebbles are dominant in soils with low clay content. These characteristics all indicate that the soil, which began to form in late Holocene time, is not well developed. The SOM and SOC contents are closely correlated and decrease with depth. Thus, SOM determined by the simple and quick loss on ignition method (LOI) can be substituted for SOC determined by the time-consuming and expensive Walkley-Black method (WB). Both SOM and SOC decrease with depth, but in contrast to a commonly reported result, their ratio, SOM/SOC, does not increase with depth in some of our profiles. This is attributed to periglacial processes that prevent organic matter with oxygen-functional groups from moving downward in the soil profiles. Periglacial processes may also disturb the soil layers through gelifluction. Consequently organic carbon does not decrease with depth in the profiles as it commonly does in low altitude areas. This is potentially significant in understanding the degradation and development of landforms in Tibetan landscape.
13027698 Della Favera, Jorge C. (Consultant, Rio de Janeiro, Brazil). Paleozoic ice-gouging in the Parnaiba Basin, Brazil [abstr.]: in Gondwana 14; abstracts (Schmitt, Renata da Silva, editor; et al.), International Gondwana Symposium, 14, p. 178, 2011. Meeting: 14th international Gondwana symposium, "Reuniting Gondwana; the East meets the West", Sept. 25-30, 2011, Buzios, Brazil.
13029242 Myllymaki, Sari (University of Turku, Department of Geography and Geology, Turku, Finland); Sundblad, Krister; Korkka-Niemi, Kirsti; Varjol, Eila; Valkama, Mira and Huopalahti, Rainer. Pathways of metals from bedrock and soil into water and berries in the Sarvlaxviken area, SE Finland [abstr.]: in Programme and abstracts; 25th international applied geochemistry symposium 2011 (Sarala, Pertti, editor; et al.), Vuorimiesyhdistyksen Tutkimusseloste. Sarja B, 92-1, p. 88, 3 ref., 2011. compact disc, WWW. Meeting: 25th international applied geochemistry symposium, Aug. 22-26, 2011, Rovaniemi, Finland. Accessed on March 13, 2013.
13034539 Kaufmann, Viktor (Graz University of Technology, Institute of Remote Sensing and Photogrammetry, Graz, Austria) and Ladstädter, Richard. Documentation and visualization of the morphodynamic of Hinteres Langtalkar rock glacier (Hohe Tauern Range, Austrian Alps) based on aerial photographs (1954-2006) and geodetic measurements (1999-2007): in Proceedings of the 10th international symposium on High mountain remote sensing cartography (Kaufmann, Viktor, editor; et al.), Grazer Schriften der Geographie und Raumforschung, 45, p. 103-116, illus. incl. 2 tables, sketch map, 22 ref., 2010. Meeting: 10th international symposium on High mountain remote sensing cartography, Sept. 12-19, 2008, Kathmandu, Nepal.
Hinteres Langtalkar rock glacier (46°59'N, 12°47'E) is located in a glacially shaped cirque situated in the center of the Schober group of the Hohe Tauern range, Austria. This tongue-shaped creep phenomenon of mountain permafrost is approx. 850 m long, 200 to 350 m wide, and stretches vertically between 2455 m and 2725 m altitude. Over the course of time, the snout of the rock glacier has advanced into the uppermost cirque's lip, which is much steeper than the cirque floor behind, causing disintegration of this part of the rock glacier through active sliding processes (since 1994). Consequently, flow velocities behind the frontal slope have significantly increased because of a lack of counterpressure. Maximum horizontal flow velocities reached 2 to 2.5 m a-1. The prevailing high longitudinal strain rates of up to 20´10-3 a-1 (2002-2006) have triggered surface ruptures and crevasse-like openings. In this paper we present quantitative information on the kinematics and surface deformation of the rock glacier based on the photogrammetric evaluation of multi-temporal aerial photographs (10 different epochs between 1954 and 2006) and annual geodetic measurements (1999-2007). Results obtained from recent investigations are highlighted. Based on the available information, covering a time span of 52 years, we analyze the changing kinematic state of Hinteres Langtalkar rock glacier. Special emphasis is put on the more recent situation of the rock glacier, which is characterized by the rapid development of tension cracks and the accelerated disintegration of the permafrost body. The main findings of this paper are as follows: (1) There is most probably a persistent climatically-induced permafrost melt in the order of a few centimeters per year. (2) Specific topographic situations (e.g. increasing slope inclination) may cause acceleration of flow/creep of a rock glacier, with the implication of possible surface ruptures in case of high strain rates and insufficient internal cohesion. (3) Interannual changes of flow/creep velocities are most probably due to the thermal conditions of the permafrost body, more or less true irrespective of (2). Furthermore, the authors propose to augment the present monitoring program by a high-resolution airborne laser scanning (ALS) mission which should be repeated (at least once) at a time interval of several years depending on the height accuracy to be achieved and the prevailing permafrost melt.
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13035463 Riseborough, D. W.; Wolfe, S. A. and Duchesne, C. Permafrost modelling in northern Great Slave region, Northwest Territories; Phase 1, Climate data evaluation and 1-D sensitivity analysis: Open-File Report - Geological Survey of Canada, Rep. No. 7333, 50 p., illus. incl. tables, 50 ref., 2013. WWW. Accessed on April 16, 2013.
Climate variables were examined to evaluate their use in permafrost models, using data for Yellowknife Northwest Territories, Canada as an example. Results suggest that conversion of the annual temperature cycle to a sine wave is an acceptable approximation, as long as the wave retains the correct values for the annual freezing and thawing degree-day totals. Changes in snow depth can be approximated by a parabolic accumulation function. The delay of snow cover initiation with respect to the start of the freezing season, the snow accumulation function, and snow density are all critical, whereas end-of-season snowpack evolution is of secondary importance. Modelling results show that any difference in substrate materials produces a change in the mean annual temperature at the top-of-perennially frozen/unfrozen ground (TTOP) and annual maximum freezing/thawing layer thickness (AFTT). The greatest differences in TTOP were produced by changes in the thickness and degree of saturation of the surface organic layer. Intermediate differences were due to differences in substrate materials within and immediately below the annual freezing/thawing layer itself, and the smallest differences were due to variations in the substrate well below the thickness of the annual freezing/thawing layer. These results suggest that knowledge or consideration of the thickness and moisture content of organic soil veneers will be vital to permafrost mapping in this environment.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13035388 Dallimore, S. R.; Yamamoto, K.; Wright, J. F. and Bellefleur, G., editors. Scientific results from the JOGMEC/NRCan/Aurora Mallik 2007-2008 gas hydrate production research well program, Mackenzie Delta, Northwest Territories, Canada: Bulletin - Geological Survey of Canada, Rep. No. 601, 291 p. (French sum.), illus. incl. tables, 2012. ISBN: 978-1-100-21522-8 WWW. Accessed on April 11, 2013.
The JOGMEC/NRCan/Aurora Mallik 2007-2008 Gas Hydrate Production Research Well Program is the third major research-and-development endeavour carried out since 1998 at the Mallik site in the Mackenzie Delta of Canada's Northwest Territories. In just over a decade, the research enabled through these programs has literally moved a new energy field from unproven scientific concepts to proof-of-concept for a safe and sustainable method to produce gas hydrate, a unique and unusual solid form of natural gas. While there have been many contributors from around the world during each program, one constant has been the leadership provided by Japan and Canada. For Japan, the research forms part of a national strategy to secure a new domestic energy resource from the production of marine gas hydrate deposits that are found in abundance off its coasts. The Ministry of Economy, Trade, and Industry, through the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium), has assigned the responsibility for guiding much of this research to the Japan Oil, Gas and Metals National Corporation. In Canada, Natural Resources Canada has led the research and development studies aimed at quantifying and evaluating the energy potential of the permafrost gas hydrate deposits in the Arctic, and marine gas hydrate deposits off Canada's coasts. The most recent field program has also included, for the first time, a lead agency from the north. Aurora College, an agency of the Government of the Northwest Territories, has acted as the Designated Operator for the program, responsible for all field activities. The 15 technical research papers and accompanying databases presented in this publication comprise the third Geological Survey of Canada bulletin on Mallik gas hydrate research-and-development endeavours. With more than 100 peer-reviewed papers compiled in these volumes, they chronicle a truly remarkable record of scientific accomplishment and fulfil the intent of Canada and Japan to undertake our gas hydrate research and development for the benefit of all. Without doubt, the highlight of this phase of the research has been to establish proof-of-concept for a simple and effective gas hydrate production technique. From a broader perspective, however, the body of work we advanced has also addressed many scientific unknowns and thereby improved techniques for quantifying the distribution of gas hydrate in nature, and understanding its physical properties and the role it plays in ongoing natural geological processes. We are indebted to the many hundreds of scientists, engineers, and workers who have contributed tirelessly to move an entirely new energy field forward.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13028438 Dyurgerov, Mark B. (University of Colorado at Boulder, Institute for Arctic and Alpine Research, Boulder, CO) and Meier, Mark F. Glacier mass changes and their effect on the Earth system: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A192-A223, illus. incl. 1 table, sketch maps, 2012.
13028440 Hall, Dorothy K. (NASA, Goddard Space Flight Center, Cryospheric Sciences Laboratory, Greenbelt, MD) and Robinson, David A. Global snow cover: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A313-A344, illus. incl. 2 tables, sketch maps, 130 ref., 2012.
13028443 Heginbottom, J. Alan (Geological Survey of Canada, Ottawa, ON, Canada); Brown, Jerry; Humlum, Ole and Svensson, Harald. Permafrost and periglacial environments: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A425-A496, illus. incl. 1 table, geol. sketch maps, 208 ref., 2012.
13028442 Jeffries, Martin O. (University of Alaska at Fairbanks, Geophysical Institute, Fairbanks, AK); Morris, Kim and Duguay, Claude R. Floating ice; lake ice and river ice: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A381-A424, illus. incl. 2 tables, sketch maps, 266 ref., 2012.
13028084 Makila, Markku (Geological Survey of Finland, Espoo, Finland); Loukola-Ruskeeniemi, Kirsti and Saavuori, Heikki. High pre-mining metal concentrations and conductivity in peat around the Talvivaara nickel deposit, eastern Finland: Tutkimusraportti - Geologian Tutkimuskeskus = Report of Investigation - Geological Survey of Finland, Rep. No. 196, 36 p. (Finnish sum.), illus. incl. 7 tables, sketch maps, 49 ref., 2012. ISBN: 978-952-217-194-8; 978-952-217-195-5. Accessed on March 13, 2013.
The Talvivaara Ni-Cu-Zn-Co deposit contains more than 1500 Mt of low-grade ore, and has been mined since 2008 (0.22% Ni, 0.13% Cu, 0.49% Zn, 0.02% Co). Three peat study sites representing different bedrock types and hydrological conditions were sampled in the Talvivaara area in 2005, before the large-scale mining activities began. The chemical and physical properties of peat were studied from 58 samples. The chemical concentrations of peat were affected by factors such as the capillary transport of water through the underlying sandy till, plant physiology and geochemical processes in peat. The concentrations of Co, Cu, Fe, Mn, Ni, U, Zn and S and conductivity were lower at the study site on mica schist bedrock than in peat at the two study sites underlain by so-called black schists (metasedimentary rocks rich in graphite and sulphides). These metals displayed greater concentrations in the bottom layers of Carex (sedge) peat than in the surface layer of Sphagnum (moss) -dominated peat. It seems likely that hydrological conditions at one sloping peatland site underlain by black schist have been conducive to production and transport of acidic surface waters with metal-rich suspension from adjacent Ni-rich black schist outcrops and glacial till throughout the entire history of peat accumulation. The peat layer evidently functioned in the same way as peat filters in the remediation of acid mine drainage in present-day mine environments, i.e. metals were retained in the peat. Ditches also locally reached the underlying Ni-rich bedrock and/or Ni-rich glacial till. At this black schist study site, pH values varied between 2.8-3.8 beneath the surface peat layer. These pH values are lower than can be tolerated by Carex peat-forming plants. The acidity of peat changed in the 1960s when the peat became drier due to drainage of the the peatland, and sulphur oxidized to SO4. We conclude that in sulphide-rich terrain, sulphur concentrations in peat can be high, and leaching of sulphur from peat to surface waters during and after peatland drainage activities may lead to environmental problems. The conductivity probe developed at the Geological Survey of Finland provides a cost-effective tool for locating sulphide-rich peat formations.
13034821 Markon, Carl J. (U. S. Geological Survey); Trainor, Sarah F. and Chapin, F. Stuart, III, editors. The United States National Climate Assessment; Alaska technical regional report: U. S. Geological Survey Circular, Rep. No. C 1379, 148 p., illus. incl. 8 tables, sketch maps, 613 ref., 2012. Accessed on April 2, 2013; includes appendices.
The Alaskan landscape is changing, both in terms of effects of human activities as a consequence of increased population, social and economic development and their effects on the local and broad landscape; and those effects that accompany naturally occurring hazards such as volcanic eruptions, earthquakes, and tsunamis. Some of the most prevalent changes, however, are those resulting from a changing climate, with both near term and potential upcoming effects expected to continue into the future. Alaska's average annual statewide temperatures have increased by nearly 4°F from 1949 to 2005, with significant spatial variability due to the large latitudinal and longitudinal expanse of the State. Increases in mean annual temperature have been greatest in the interior region, and smallest in the State's southwest coastal regions. In general, however, trends point toward increases in both minimum temperatures, and in fewer extreme cold days. Trends in precipitation are somewhat similar to those in temperature, but with more variability. On the whole, Alaska saw a 10-percent increase in precipitation from 1949 to 2005, with the greatest increases recorded in winter. The National Climate Assessment has designated two well-established scenarios developed by the Intergovernmental Panel on Climate Change (Nakicenovic and others, 2001) as a minimum set that technical and author teams considered as context in preparing portions of this assessment. These two scenarios are referred to as the Special Report on Emissions Scenarios A2 and B1 scenarios, which assume either a continuation of recent trends in fossil fuel use (A2) or a vigorous global effort to reduce fossil fuel use (B1). Temperature increases from 4 to 22°F are predicted (to 2070-2099) depending on which emissions scenario (A2 or B1) is used with the least warming in southeast Alaska and the greatest in the northwest. Concomitant with temperature changes, by the end of the 21st century the growing season is expected to lengthen by 15-25 days in some areas of Alaska, with much of that corresponding with earlier spring snow melt. Future projections of precipitation (30-80 years) over Alaska show an increase across the State, with the largest changes in the northwest and smallest in the southeast. Because of increasing temperatures and growing season length, however, increased precipitation may not correspond with increased water availability, due to temperature related increased evapotranspiration. The extent of snow cover in the Northern Hemisphere has decreased by about 10 percent since the late 1960s, with stronger trends noted since the late 1980s. Alaska has experienced similar trends, with a strong decrease in snow cover extent occurring in May. When averaged across the State, the disappearance of snow in the spring has occurred from 4 to 6 days earlier per decade, and snow return in fall has occurred approximately 2 days later per decade. This change appears to be driven by climate warming rather than a decrease in winter precipitation, with average winter temperatures also increasing by about 2.5°F. The extent of sea ice has been declining, as has been widely published in both national and scientific media outlets, and is projected to continue to decline during this century. The observed decline in annual sea ice minimum extent (September) has occurred more rapidly than was predicted by climate models and has been accompanied by decreases in ice thickness and in the presence of multi-year ice. This decrease was first documented by satellite imagery in the late 1970s for the Bering and Chukchi Seas, and is projected to continue, with the potential for the disappearance of summer sea ice by mid- to late century. A new phenomenon that was not reported in previous assessments is ocean acidification. Uptake of carbon dioxide (CO2) by oceans has a significant effect on marine biogeochemistry by reducing seawater pH. Ocean acidification is of particular concern in Alaska, because cold sea water absorbs CO2 more rapidly than warm water, and a decrease in sea ice extent has allowed increased sea surface exposure and more uptake of CO2 into these northern waters. Ocean acidification will likely affect the ability of organisms to produce and maintain shell material, such as aragonite or calcite (calcium carbonate minerals structured from carbonate ions), required by many shelled organism, from mollusks to corals to microscopic organisms at the base of the food chain. Direct biological effects in Alaska further along the food chain have yet to be studied and may vary among organisms. Some of the potentially most significant changes to Alaska that could result from a changing climate are the effects on the terrestrial cryosphere--particularly glaciers and permafrost. Alaskan glaciers are changing at a rapid rate, the primary driver appearing to be temperature. Statewide, glaciers lost 13 cubic miles of ice annually from the 1950s to the 1990s, and that rate doubled in the 2000s. However, like temperature and precipitation, glacier ice loss is not spatially uniform; most glaciers are losing mass, yet some are growing (for example Hubbard Glacier in southeast Alaska). Alaska glaciers with the most rapid loss are those terminating in sea water or lakes. With this increasing rate of melt, the contribution of surplus fresh water entering into the oceans from Alaska's glaciers, as well as those in neighboring British Columbia, Canada, is approximately 20 percent of that contributed by the Greenland Ice Sheet. Permafrost degradation (that is, the thawing of ice-rich soils) is currently (2012) impacting infrastructure and surface-water availability in areas of both discontinuous and continuous ground ice. Over most of the State, the permafrost is warming, with increasing temperatures broadly consistent with increasing air temperatures. On the Arctic coastal plain of Alaska, permafrost temperatures showed some cooling in the 1950s and 1960s but have been followed by a roughly 5°F increase since the 1980s. Many areas in the continuous permafrost zone have seen increases in temperature in the seasonally active layer and a decrease in re-freezing rates. Changes in the discontinuous permafrost zone are initially much more observable due to the resulting thermokarst terrain (land surface formed as ice rich permafrost thaws), most notable in boreal forested areas. Climate warming in Alaska has potentially broad implications for human health and food security, especially in rural areas, as well as increased risk for injury with changing winter ice conditions. Additionally, such warming poses the potential for increasing damage to existing water and sanitation facilities and challenges for development of new facilities, especially in areas underlain by permafrost.
13028441 Parkinson, Claire L. (NASA, Goddard Space Flight Center, Cryospheric Sciences Laboratory, Greenbelt, MD) and Cavalieri, Donald J. Floating ice; sea ice: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A345-A380, illus. incl. sketch maps, 2012.
13028439 Raup, Bruce H. (University of Colorado, National Snow and Ice Data Center, Boulder, CO) and Kargel, Jeffrey S. Global Land Ice Measurements from Space (GLIMS): in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A247-A260, illus. incl. sketch maps, 2012.
13028437 Thompson, Lonnie G. (Ohio State University, Department of Geological Sciences, Columbus, OH). Ice cores, high-mountain glaciers, and climate: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A157-A171, illus. incl. 2 tables, sketch maps, 2012.
13028435 Williams, Richard S., Jr. (U. S. Geological Survey, Woods Hole, MA) and Ferrigno, Jane G. Glaciers: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A69-A312, illus. incl. 7 tables, sketch maps, 1172 ref., 2012. Individually authored sections are cited separately.
13028432 Williams, Richard S., Jr. (U. S. Geological Survey, Woods Hole, MA) and Ferrigno, Jane G., editors. Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments: U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, 496 p., illus., 2012. Individual papers are cited separately; includes supplemental notes in back pocket.
13028436 Williams, Richard S., Jr. (U. S. Geological Survey). Glaciers of the subantarctic islands: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A105-A109, illus. incl. 1 table, sketch map, 2012.
13028433 Williams, Richard S., Jr. (U. S. Geological Survey, Woods Hole, MA). Introduction; changes in the Earth's cryosphere and global environmental change in the Earth system: in Satellite image atlas of glaciers of the world; state of the Earth's cryosphere at the beginning of the 21st century; glaciers, global snow cover, floating ice, and permafrost and periglacial environments (Williams, Richard S., Jr., editor; et al.), U. S. Geological Survey Professional Paper, Rep. No. P 1386-A, p. A1-A34, illus. incl. 1 table, 2012.
13034120 Pihlaja, Jouni and Johansson, Peter. Stop 1; Boulder fields and test areas on the Levi Fell: in Late Pleistocene glacigenic deposits from the central part of the Scandinavian ice sheet to Younger Dryas end moraine zone; INQUA Peribaltic Working Group meeting and excursion, northern Finland; excursion guide (Johansson, Peter, editor; et al.), p. 11-13, illus., 2 ref., 2011. Available from: Geological Survey of Finland, Rovaniemi, Finland. Field guide accompanies the INQUA Peribaltic Working Group meeting and excursion, held in Utsjoki, Finland, June 12-17, 2011. Accessed on April 4, 2013.
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13035411 Hannigan, P. K. A GIS petroleum prospectivity map of the northern mainland of Canada (Mackenzie Corridor): Open-File Report - Geological Survey of Canada, Geological Survey of Canada, Calgary, AB, Canada, Rep. No. 7110, 11 p., illus. incl. tables; economic geology map, 1:1,000, 2013. WWW. Accessed on April 11, 2013.
As part of Geomapping for Energy and Minerals (GEM) activities for Canada's north, participants in the Mackenzie Delta and Corridor project have co-operated to produce a new digital map illustrating areas of varying petroleum potential in Canada's northern mainland, specifically in the region commonly known as the Mackenzie Corridor which encompasses areas of sedimentary rock along and proximal to the Mackenzie River and includes the proposed route of the Mackenzie Valley natural gas pipeline. The map, released in the GCS North American 1983 horizontal projection system using the GRS 80 ellipsoid and NAD 1983 horizontal datum, includes complete coverage of areas of petroleum potential in the Interior Platform and Northern Foreland Belt geological provinces between latitudes 60° and 70° north.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13035431 Oviatt, N. M. and Paulen, R. C. Surficial geology, Breynat Point, Northwest Territories, NTS 85-B/15: Geological Survey of Canada, Canadian Geoscience Map, Geological Survey of Canada, Ottawa, ON, Canada, Rep. No. 114, 1 sheet (French sum.), glacial geology map, 1:50,000, 10 ref., 2013. ISBN: 978-1-100-21746-8 WWW. Preliminary edition. Accessed on April 11, 2013.
The Pine Point region is of very low relief and characterized by black spruce bogs with local relief not exceeding 20 m. During Wisconsin time, the Breynat Point map sheet was actively and continuously glaciated by the Laurentide Ice Sheet which was generally flowing to the west. Multiple till units were observed in the open pits, however only the uppermost unit was mapped at surface. The map area was completely inundated by proglacial Lake McConnell which formed during deglaciation, glaciolacustrine sediments are the dominant materials that occur as beach ridges and littoral sediments. Reworked beach ridges form eolian dunes up to 15 m high. Raised strandlines formed by earlier phases of Great Slave Lake mark the former isostatic rebound of the land surface. Organic deposits are extensive with mature peatlands and fens, which are underlain by discontinuous permafrost with active thermokarst. Abandoned open pits and waste piles pockmark the former Pine Point mining district.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13035475 St-Onge, D. A. and Kerr, D. E. Reconnaissance surficial geology, Jervoise River, Nunavut, NTS 66-E, north half: Geological Survey of Canada, Canadian Geoscience Map, Geological Survey of Canada, Ottawa, ON, Canada, Rep. No. 131, 1 sheet (French sum.), glacial geology map, 1:125,000, 2013. ISBN: 978-1-100-22027-7 WWW. Preliminary edition. Accessed on April 11, 2013.
Preliminary surficial geology studies, through aerial photograph interpretation and limited legacy data, were undertaken in the north half of the Jervoise River map area to provide an improved understanding of distribution and nature of surficial sediments, and regional glacial history. Widespread till veneer, hummocky till and streamlined till are common across the map area. Some areas of till are dissected by north-northwestward to northward trending glaciofluvial corridors consisting of eskers, ice-contact sediments, outwash plains, and locally zones of scoured bedrock. Small isolated glacial lakes were formed by ponding of meltwater, and their sediments are now characterized by thermokarst terrain. In the central area, a discontinuous moraine complex, consisting of glaciofluvial ridged sediments, ice-contact outwash plains and till ridges, forms part of the western segment of a major end moraine system referred to as the MacAlpine Moraine. Drumlins and crag-and-tails record a regional north-northwestward ice flow during the last glaciation. Rivers have reworked and deposited extensive alluvial sediments.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
13035405 Stevens, C. W.; Wolfe, S. A. and Gaanderse, A. J. R. Lithalsa distribution, morphology and landscape associations in the Great Slave Lowlands, Northwest Territories: Open-File Report - Geological Survey of Canada, Geological Survey of Canada, Calgary, AB, Canada, Rep. No. 7255, 41 p., illus. incl. tables; glacial geology map, 1:166,666, 40 ref., 2012. WWW. Accessed on April 11, 2013.
The distribution of ice-rich terrain is an important geotechnical consideration for the engineering of northern infrastructure. Lithalsas represent one form of ice-rich terrain that can be identified on the basis of surface geomorphology and cryostratigraphy. A total of 1,777 ice-rich lithalsas were mapped over 3,680 km2 using monochromatic stereo-pair airphotos, across the Great Slave Lowlands and Uplands, NWT, Canada. Boreholes indicate lithalsas in this region consist of ice-rich silt and clay, with segregated ice lenses up to 10 cm thick. Three distinct morphologies are recognized from LiDAR bare-earth DEMs including; (i) circular, (ii) linear and (iii) crescentic plan-view shapes, which exhibit hill-like or ridge-like forms up to 8 m in height and more than 100 m in width. The linear relationship between lithalsa height and width indicates that 1 cm of vertical growth may be accompanied by 15 cm of lateral growth at the peripheral edges. Lithalsa distribution is skewed towards lower elevations, with 97.7% located within the Great Slave Lowlands. These features predominantly occur adjacent to water bodies and follow the regional distribution of frost susceptible glaciolacustrine silt and clay. Landscape associations suggest lithalsa formation is controlled by sedimentological, thermal and hydrological conditions. This Open File reports the first account of lithalsas within this region.
URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.downloade.fl&id ...
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