Permafrost Monthly Alerts (PMAs)

14025158 Williams, Tyler J. (Wilfrid Laurier University, Cold Regions Research Centre, Waterloo, ON, Canada); Quinton, William L. and Baltzer, Jennifer L. Linear disturbances on discontinuous permafrost; implications for thaw-induced changes to land cover and drainage patterns: Environmental Research Letters, 8(2), Paper no. 025006, illus. incl. 2 tables, sketch maps, 29 ref., June 2013.

Within the zone of discontinuous permafrost, linear disturbances such as winter roads and seismic lines severely alter the hydrology, ecology, and ground thermal regime. Continued resource exploration in this environment has created a need to better understand the processes causing permafrost thaw and concomitant changes to the terrain and ground cover, in order to efficiently reduce the environmental impact of future exploration through the development of best management practices. In a peatland 50 km south of Fort Simpson, NWT, permafrost thaw and the resulting ground surface subsidence have produced water-logged linear disturbances that appear not to be regenerating permafrost, and in many cases have altered the land cover type to resemble that of a wetland bog or fen. Subsidence alters the hydrology of plateaus, developing a fill and spill drainage pattern that allows some disturbances to be hydrologically connected with adjacent wetlands via surface flow paths during periods of high water availability. The degree of initial disturbance is an important control on the extent of permafrost thaw and thus the overall potential recovery of the linear disturbance. Low impact techniques that minimize ground surface disturbance and maintain original surface topography by eliminating windrows are needed to minimize the impact of these linear disturbances. Copyright 2013 IOP Publishing Ltd

DOI: 10.1088/1748-9326/8/2/025006

14028195 Dolnicki, Piotr (Uniwersytet Pedagogiczny, Instytut Geografii, Cracow, Poland); Grabiec, Mariusz; Puczko, Dariusz; Gawor, Lukasz; Budzik, Tomasz and Klementowski, Jan. Variability of temperature and thickness of permafrost active layer at coastal sites of Svalbard: Polish Polar Research, 34(4), p. 353-374, illus. incl. 1 table, 65 ref., 2013.

We present the variability of the thermal state and thickness of permafrost active layer at the raised marine beaches in Svalbard. The investigations were carried out using direct probing, thaw tube, ground temperature and radar soundings at Holocene strand plains 10-20 m a.s.l. in Fuglebergsletta (SW Spitsbergen) and at the shore of Kinnvika Bay (Nordaustlandet). Their results were compared to those obtained at other coastal sites in Svalbard. The ground temperature measurements were conducted in 2009 on August, recognized as the standard month for the maximum thawing during the last decade. The studied sites are typical for close to extreme active layer conditions on Svalbard. In Hornsund, the thawing depth exceeded 2 m, while in Kinnvika the active layer was thinner than 1 m. In Svalbard, the depth of thawing decreases generally from south to north and from the open sea coast to the central parts of islands. These differences are the consequence of diverse climatic conditions strongly determined by the radiation balance modified by a number of regional (e.g. ocean circulation) and local (e.g. duration of snow deposition) conditions.

DOI: 10.2478/popore-2013-0026

14027228 Overeem, Irina (Institute of Arctic and Alpine Research, Boulder, CO). Scientists go to extremes to monitor Arctic permafrost loss: Earth, 59(4), p. 24-31, illus. incl. sketch map, April 2014.

URL: http://www.earthmagazine.org/article/scientists-go-extremes-monitor-arctic-perma ...

14023881 MacDougall, Andrew H. (University of Victoria, School of Earth and Ocean Science, Victoria, BC, Canada); Avis, Christopher A. and Weaver, Andrew J. Significant contribution to climate warming from the permafrost carbon feedback: Nature Geoscience, 5(10), p. 719-721, illus., 14 ref., October 2012.

DOI: 10.1038/ngeo1573

14025862 Max, M. D. (2457 39th Place NW, Washington, DC) and Johnson, A. H. Hydrate petroleum system approach to natural gas hydrate exploration: Petroleum Geoscience, Pre-Issue Publication, illus. incl. 1 table, 70 ref., March 21, 2014.

Natural gas hydrate (NGH) is a solid crystalline material composed of water and natural gas (primarily methane) that is stable under conditions of moderately high pressure and moderately low temperature found in permafrost and continental margin sediments. A NGH petroleum system is different in a number of important ways from conventional petroleum systems related to large concentrations of gas and petroleum. The critical elements of the NGH petroleum system are: (1) a gas hydrate stability zone (GHSZ) in which pressure and temperature lie within the field of hydrate stability, creating a thermodynamic trap of suitable thickness for NGH concentrations to form; (2) recent and modern gas flux into the GHSZ along migration pathways; and (3) suitable sediment host sands within the GHSZ. These elements have to be active now and in the recent geological past. Exploration in continental margin sediments includes basin analysis to identify source and host sediment likelihood and disposition, potential reservoir localization using existing seismic analysis tools for locating turbidite sands and estimating NGH saturation, and deposit characterization using drilling and logging. Drilling has validated first-order seismic analysis techniques for identifying and quantifying NGH using rock physics mechanical models.

DOI: 10.1144/petgeo2012-049

14028060 Sidorov, A. A. (Russian Academy of Sciences, Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Moscow, Russian Federation) and Volkov, A. V. Oil occurrences of northeastern Russia: Doklady Earth Sciences, 453(1), p. 1086-1089, illus. incl. sketch map, 11 ref., November 2013.

This paper shows that the location of large petroleum and gas hydrate deposits is related to deep ore-controlling fault zones. The large mercury deposits within these zones testify to the high differentiation maturity of the deep and crustal fluids. The mercury mineralization in compound ore assemblages is considered as the main indicator of their maturity (stable duration of development). The petroleum occurrences in Cenozoic sedimentary basins reflect only some partial changes in the location of hydrocarbon deposits with regard to the neotectonics and dynamics of the permafrost rocks. Copyright 2013 Pleiades Publishing, Ltd.

DOI: 10.1134/S1028334X13110172

14023115 Scotti, Riccardo (Universita degli Studi Milano-Bicocca, Dipartimento di Scienze Geologiche e Geotecnologie, Milan, Italy); Brardinoni, Francesco; Alberti, Stefano; Frattini, Paolo and Crosta, Giovanni B. A regional inventory of rock glaciers and protalus ramparts in the Central Italian Alps: Geomorphology, 186, p. 136-149, illus. incl. 3 tables, sketch maps, 98 ref., March 15, 2013.

We present a regional inventory of rock glaciers (n=1514) and protalus ramparts (228) for the Lombardy region, central Italian Alps. To identify and classify the landforms we inspect three sequential air-orthophoto mosaics and a 2m-DSM, and conduct confirmatory field work. The inventory forms an empirical basis to analyze: (i) the relative contribution of hillslope (i.e., talus slopes) and glacial (i.e., moraines) sediment stores to rock glacier sediment supply; (ii) linkages between the landforms inventoried and local topographic attributes; (iii) the spatial variability of periglacial activity in relation to a parsimonious set of environmental variables (i.e., elevation, precipitation, and lithology); and (iv) the effects of the Pleistocene-Holocene climatic transition on the distribution of intact and relict landforms. This analysis reveals that the elevation of rock glacier termini can vary over 200 m as a function of slope aspect. In turn, the distribution of rock glaciers among aspect categories is controlled by the structure of the valley network that promotes NW and SE exposures. Talus rock glaciers prevail numerically over the glacier-related typology, even though the latter population appears to have increased during the Holocene. Relict and intact rock glaciers have distinct spatial patterns in that the former display, on average, a 400-m elevation drop and a less clustered distribution towards northern aspects, suggesting that they have developed in more "permafrost-prone" climatic conditions. Analyzing the study region through a 27.5 km-grid has been instrumental for showing that the rock glacier specific area and terminus elevation are: (i) positively correlated with terrain elevation; and (ii) negatively correlated with mean annual precipitation. As a consequence, in relation to Holocene generalized atmospheric temperature rise, intact rock glaciers have progressively disappeared from the wetter and milder portions of the central Italian Alps. Analysis of rock glacier occurrence across litho-tectonic sectors does not provide conclusive dependences and requires further analysis. This inventory, which represents a necessary preliminary step for modelling the spatial distribution of discontinuous permafrost at the regional scale, fills a critical geographic gap in the context of ongoing permafrost research in the European Alps (e.g., PermaNET). Abstract Copyright (2013) Elsevier, B.V.

DOI: 10.1016/j.geomorph.2012.12.028

14027958 Szymanski, Wojciech (Uniwersytet Jagiellonski, Instytut Geografii i Gospodarki Przestrzennej, Cracow, Poland); Skiba, Stefan and Wojtun, Bronislaw. Distribution, genesis, and properties of Arctic soils; a case study from the Fuglebekken Catchment, Spitsbergen: Polish Polar Research, 34(3), p. 289-304, illus. incl. 3 tables, sketch map, 40 ref., 2013.

This paper presents distribution and properties of soils within the Fuglebekken catchment in neighbourhood of the Polish Polar Station in Homsund, SW Spitsbergen (Svalbard Archipelago). The present study describes 8 representative soil profiles out of 34 profiles studied for the whole catchment. Soils of the Fuglebekken catchment show initial stage of their formation because of very slow rate of chemical and biological weathering in Arctic climate conditions. Uplifted marine terraces of the Fuglebekken catchment are characterized by domination of Haplic Cryosols which are related to stony and gravelly parent material (reworked marine sediments). Such soils constitute of 17% of the studied area. Turbic Cryosols forming characteristic micro-relief occur on flat surfaces and gentle slopes. Such soils (covering 7% of the catchment) are formed from loamy parent material. Along streams Hyperskeletic Cryosols (Reductaquic) and Turbic Histic Cryosols occur. The last two soil units (constituting 11% of the catchment) are mantled by continuous and dense vegetation cover (especially mosses) due to high content of water rich in nutrients flowing from colonies of sea birds located on slopes of Ariekammen and Fugleberget. The studied soils are generally characterized by shallow occurrence of permafrost (i.e. at 30-50 cm), high content of pebbles, sandy or sandy loam texture, and neutral or slightly alkaline reaction. Soils occurring along streams and near colonies of sea birds show higher content of nutrients (N and P) in comparison with other soils and are covered by more dense vegetation. This indicates important impact of bird guano on chemical composition of soil solution and fertility of such soils.

DOI: 10.2478/popore-2013-0017

14024089 Hanks, Catherine L. (University of Alaska at Fairbanks, Geophysical Institute, Fairbanks, AK); Shimer, Grant; Kohshour, Iman Oraki; Ahmadi, Mohabbat; McCarthy, Paul J.; Dandekar, Abhijit; Mongrain, Joanna and Wentz, Raelene. Integrated reservoir characterization and simulation of a shallow, light-oil, low-temperature reservoir; Umiat Field, National Petroleum Reserve, Alaska: AAPG Bulletin, 98(3), p. 563-585, illus. incl. sects., strat. cols., 7 tables, geol. sketch maps, 30 ref., March 2014.

Umiat field in northern Alaska is a shallow, light-oil accumulation with an estimated original oil in place of more than 1.5 billion bbl and 99 bcf associated gas. The field, discovered in 1946, was never considered viable because it is shallow, in permafrost, and far from any infrastructure. Modern drilling and production techniques now make Umiat a more attractive target if the behavior of a rock, ice, and light oil system at low pressure can be understood and simulated. The Umiat reservoir consists of shoreface and deltaic sandstones of the Cretaceous Nanushuk Formation deformed by a thrust-related anticline. Depositional environment imparts a strong vertical and horizontal permeability anisotropy to the reservoir that may be further complicated by diagenesis and open natural fractures. Experimental and theoretical studies indicate that there is a significant reduction in the relative permeability of oil in the presence of ice, with a maximum reduction when connate water is fresh and less reduction when water is saline. A representative Umiat oil sample was reconstituted by comparing the composition of a severely weathered Umiat fluid to a theoretical Umiat fluid composition derived using the Pedersen method. This sample was then used to determine fluid properties at reservoir conditions such as bubble point pressure, viscosity, and density. These geologic and engineering data were integrated into a simulation model that indicate recoveries of 12%-15% can be achieved over a 50-yr production period using cold gas injection from five well pads with a wagon-wheel configuration of multilateral wells.

DOI: 10.1306/08201313011

14028232 Kluge, Tobias (Yale University, Department of Geology and Geophysics, New Haven, CT); Affek, Hagit P.; Zhang, Yi Ge; Dublyansky, Yuri; Spötl, Christoph; Immenhauser, Adrian and Richter, Detlev K. Clumped isotope thermometry of cryogenic cave carbonates: Geochimica et Cosmochimica Acta, 126, p. 541-554, illus. incl. 3 tables, sketch map, 50 ref., February 1, 2014.

Freezing of cave pool water that is increasingly oversaturated with dissolved carbonate leads to precipitation of a very specific type of speleothems known as cryogenic cave carbonates (CCC). At present, two different environments for their formation have been proposed, based on their characteristic carbon and oxygen isotope ratios. Rapidly freezing thin water films result in the fast precipitation of fine-grained carbonate powder (CCC_fine). This leads to rapid physicochemical changes including CO₂ degassing and CaCO₃ precipitation, resulting in significantly ¹³C-enriched carbonates. Alternatively, slow carbonate precipitation in ice-covered cave pools results in coarse crystalline CCC (CCC_coarse) yielding strongly ¹⁸O-depleted carbonate. This is due to the formation of relatively ¹⁸O-enriched ice causing the gradual depletion of ¹⁸O in the water from which the CCC precipitates. Cryogenic carbonates from Central European caves were found to have been formed primarily during the last glacial period, specifically during times of permafrost thawing, based on the oxygen isotope ratios and U-Th dating. Information about the precise conditions of CCC_coarse formation, i.e. whether these crystals formed under equilibrium or disequilibrium conditions with the parent fluid, however, is lacking. An improved understanding of CCC_coarse formation will increase the predictive value of this paleo-permafrost archive. Here we apply clumped isotopes to investigate the formation conditions of cryogenic carbonates using well-studied CCC_coarse from five different cave systems in western Germany. Carbonate clumped isotope measurements yielded apparent temperatures between 3 and 18°C and thus exhibit clear evidence of isotopic disequilibrium. Although the very negative carbonate d¹⁸O values can only be explained by gradual freezing of pool water accompanied by preferential incorporation of ¹⁸O into the ice, clumped isotope-derived temperatures significantly above expected freezing temperatures indicate incomplete isotopic equilibration during precipitation of CCC. Abstract Copyright (2014) Elsevier, B.V.

DOI: 10.1016/j.gca.2013.11.011

14023116 Ballantyne, Colin K. (University of Saint Andrews, School of Geography and Geosciences, Fife, United Kingdom) and Stone, John O. Timing and periodicity of paraglacial rock slope failures in the Scottish Highlands: Geomorphology, 186, p. 150-161, illus. incl. 3 tables, sketch map, 135 ref., March 15, 2013. Includes appendices.

Many formerly-glaciated mountains exhibit a high density of postglacial rock-slope failures (RSFs) in the form of rockslides, rock avalanches or deep-seated gravitational slope deformations. Such RSFs are often termed 'paraglacial' as they reflect pre-conditioning by glaciation and deglaciation. The temporal pattern of paraglacial RSFs is unknown. We employ 47 cosmogenic isotope exposure ages obtained for 17 catastrophic RSFs in the Scottish Highlands to test models of changes in RSF frequency since deglaciation. Our results show that RSF activity spans almost the entire postglacial period from ~17 ka until ~1.5 ka, and that the periodicity of sampled postglacial RSFs is statistically indistinguishable from a pattern of uniform periodicity (~1 ka^-1). Our data do not conform to proposed models of declining RSF frequency with time elapsed since deglaciation, but suggest that the temporal distribution of postglacial RSFs is best described by a combination of rapid response (enhanced RSF frequency during or immediately after deglaciation) followed by approximately constant periodicity. Our findings are consistent with near-surface fracturing of rock when glacially-induced confining stresses are removed, causing some failures during or immediately after deglaciation and reducing other slopes to critical conditional stability so that failure is triggered by progressive rock-mass weakening or by transient triggering mechanisms. Neither permafrost degradation (thaw of ice in joints) nor seismic activity offers a general explanation for triggering Scottish RSFs, but could be contributory in some cases. The quasi-constant periodicity inferred for Holocene RSFs implies that the probability of RSFs in this seismically-quiescent intraplate area has not changed in the past ~10 ka, and that further (though infrequent) catastrophic RSFs are likely to occur in the future. Abstract Copyright (2013) Elsevier, B.V.

DOI: 10.1016/j.geomorph.2012.12.030

14024051 Willerslev, Eske (University of Copenhagen, Natural History Museum, Copenhagen, Denmark); Davison, John; Moora, Mari; Zobel, Martin; Coissac, Eric; Edwards, Mary E.; Lorenzen, Eline D.; Vestegard, Mette; Gussarova, Galina; Haile, James; Craine, Joseph; Gielly, Ludovic; Boessenkool, Sanne; Epp, Laura S.; Pearman, Peter B.; Cheddadi, Rachid; Murray, David; Brathen, Kari Anne; Yoccoz, Nigel; Binney, Heather; Cruaud, Corinne; Wincker, Patrick; Goslar, Romasz; Alsos, Inger Greve; Bellemain, Eva; Brysting, Anne Krag; Elven, Reidar; Sonstebo, Jorn Henrik; Murton, Julian; Sher, Andrei; Rasmussen, Morten; Ronn, Regin; Mourier, Tobias; Cooper, Alan; Austin, Jeremy; Moller, Per; Froese, Duane; Zazula, Grant; Pompanon, François; Rioux, Delphine; Niderkorn, Vincent; Tikhonov, Alexei; Savvinov, Grigoriy; Roberts, Richard G.; MacPhee, Ross D. E.; Gilbert, M. Thomas P.; Kjaer, Kurt H.; Orlando, Ludovic; Brochmann, Christian and Taberlet, Pierre. Fifty thousand years of Arctic vegetation and megafaunal diet: Nature (London), 506(7486), p. 47-51, illus. incl. sketch map, 50 ref., February 6, 2014.

DOI: 10.1038/nature12921

14025159 Necsoiu, Marius (Southwest Research Institute, Geosciences and Engineering Division, San Antonio, TX); Dinwiddie, Cynthia L.; Walter, Gary R.; Larsen, Amy and Stothoff, Stuart A. Multi-temporal image analysis of historical aerial photographs and recent satellite imagery reveals evolution of water body surface area and polygonal terrain morphology in Kobuk Valley National Park, Alaska: Environmental Research Letters, 8(2), Paper no. 025007, illus. incl. 1 table, sketch maps, 72 ref., June 2013.

Multi-temporal image analysis of very-high-resolution historical aerial and recent satellite imagery of the Ahnewetut Wetlands in Kobuk Valley National Park, Alaska, revealed the nature of thaw lake and polygonal terrain evolution over a 54-year period of record comprising two 27-year intervals (1951-1978, 1978-2005). Using active-contouring-based change detection, high-precision orthorectification and co-registration and the normalized difference index, surface area expansion and contraction of 22 shallow water bodies, ranging in size from 0.09 to 179 ha, and the transition of ice-wedge polygons from a low- to a high-centered morphology were quantified. Total surface area decreased by only 0.4% during the first time interval, but decreased by 5.5% during the second time interval. Twelve water bodies (ten lakes and two ponds) were relatively stable with net surface area decreases of <10%, including four lakes that gained area during both time intervals, whereas ten water bodies (five lakes and five ponds) had surface area losses in excess of 10%, including two ponds that drained completely. Polygonal terrain remained relatively stable during the first time interval, but transformation of polygons from low- to high-centered was significant during the second time interval. Copyright 2013 IOP Publishing Ltd

DOI: 10.1088/1748-9326/8/2/025007

14025867 Martini, I. Peter (University of Guelph, School of Environmental Sciences, Guelph, ON, Canada) and Morrison, R. I. Guy. Coasts of Foxe Basin, Arctic Canada: in Sedimentary coastal zones from high to low latitudes; similarities and differences (Martini, I. Peter, editor; et al.), Special Publication - Geological Society of London, 388, illus. incl. 3 tables, geol. sketch map, 96 ref., March 12, 2014. (Online First).

Foxe Basin is a down-faulted arctic basin floored by Palaeozoic carbonates, surrounded by metamorphic Precambrian terrains. Quaternary deposits consist of Pleistocene-Holocene glacial drift, and frost-shattered bedrock-clasts mostly reworked by sea waves during post-glacial emergence during the last 5000-6000 yr. The shallow, primarily micro- to meso-tidal sea is covered by ice for c. 9-10 months each year. This ensures that the overall energy of the coasts is low, although strong storm waves develop during ice-free periods. Puccinellia phryganodes dominated salt marshes occur on muddy and sandy shores and grade into inland sedge-forb wetlands and Dryas-dominated tundra. Cold climate processes active on the emerged land have generated typical features such as frost heaving of bedrock blocks, solifluction lobes on slopes, frost boils in flatter areas, frost shattering and solution of surficial carbonate pebbles, thermokarst lakes, and shallow Cryosols.

DOI: 10.1144/SP388.14

14028093 Lisitzyn, A. P. (Russian Academy of Sciences, Shirshov Institute of Oceanology, Moscow, Russian Federation); Kravchishina, M. D.; Kopelevich, O. V.; Burenkov, V. I.; Shevchenko, V. P.; Vazyulya, S. V.; Klyuvitkin, A. A.; Novigatskii, A. N.; Politova, N. V.; Filippov, A. S. and Sheberstov, S. V. Spatial and temporal variability in suspended particulate matter concentration within the active layer of the White Sea: Doklady Earth Sciences, 453(2), p. 1228-1233, illus. incl. 1 table, sketch map, 14 ref., December 2013.

DOI: 10.1134/S1028334X13120052

14022996 Mateos, Rosa María (Instituto Geológico y Minero de España, Unidad en Illes Balears, Palma de Mallorca, Spain); García-Moreno, Inmaculada and Azañón, Jose Miguel. Freeze-thaw cycles and rainfall as triggering factors of mass movements in a warm Mediterranean region; the case of the Tramuntana Range (Majorca, Spain): Landslides, 9(3), p. 417-432, illus. incl. 5 tables, geol. sketch maps, 43 ref., September 2012.

Between 2008 and 2010, the island of Majorca (Spain) experienced the coldest and wettest winters of the last 40 years. Accumulated rainfall was twice the average and values of intense rainfall up to 296 mm/24 h were recorded, very similar to those calculated for a return period of 100 years. Additionally, high precipitation coincided with anomalous, low temperatures, with abundant snowfall and freezing in the highest zones of the Tramuntana Range, in the northwest sector of the island. As a result, 34 mass movements were recorded on the range, which seriously affected the road network in an area of great importance for tourism, as it welcomes 8.5 million visitors each year. Fourteen rockfalls, 1 rock avalanche, 15 landslides and 4 karstic collapses were inventoried. The geological structure, formed by a series of NW overlapping thrusts, determines the distribution as well as the failure pattern of the movements. Thus, the northern face of the range registered 68% of the mass movements: nine rockfalls with planar failure took place as well as all the landslides recorded. Likewise, south-facing slopes have been affected by longer runout rockfalls with a wedge-type failure. The thorough analysis of the meteorological data shows that most of the movements have taken place after antecedent rainfall over 800 mm. Additionally, the rockfalls have also occurred after several freeze-thaw cycles, being a determining and unusual factor in this warm region. Intense rainfall >90 mm/24 h also caused rockfalls as well as exceptional very intense rainfall >120 mm/24 h caused landslides. The results aim to contribute to the design of an early warning system coordinating emergency, infrastructure services and meteorological centres in a region of high risk. Copyright 2011 Springer-Verlag

DOI: 10.1007/s10346-011-0290-8

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14025561 Bronnikova, Maria (Russian Academy of Sciences, Institute of Geography, Moscow, Russian Federation); Panin, Andrey; Uspenskaya, Ol'ga; Fuzeina, Yuliya and Turova, Irina. Late Pleistocene-Holocene environmental changes in ultra-continental subarid permafrost-affected landscapes of the Terekhol' Basin, south Siberia: in Landscapes and soils through time (Sauer, Daniela, editor; et al.), Catena (Giessen), 112, p. 99-111, illus. incl. 3 tables, geol. sketch map, 48 ref., January 2014. Meeting: International conference, Landscapes and soils through time, July 29-Aug. 1, 2011, Stuttgart, Germany.

This study is an attempt to use closely related inter-complementary paleo-archives of a local landscape to access understanding of Late Pleistocene-Holocene environmental changes in the region. The study site is a small intermountain basin in the Sayan-Tuva Upland, 51°N., 97°E., 1300ma.s.l. Paleo-archives covering about 13,000 yrs were studied: paleosol-sedimentary sequences on a delta-alluvial fan of a small river, lacustrine sediments in bottom cores and on palsa-islands and soils of palsa-islands. The following sequence of environmental changes was established. The fluvial activity in the basin reached its maximum at the end of the late Pleistocene. The sharp decrease of the fluvial activity is terminated by two successive paleosols of Pleistocene-Holocene transition. The older paleosol indicates meadow-steppe (or tundra-steppe) conditions with a shallow permafrost table and impeded drainage. The younger paleosol testifies on sharp aridization, biological activity suppression, contrasting water regime, and warming. Dammed lake appeared in the midst of the trough about 11,000cal yr BP. Sedimentation on delta-alluvial fan was fairly inconsiderable in Holocene. The first part of Holocene (before 4000cal yr BP) was most balanced in annual distribution of precipitation. Runoff, even being prominently enhanced in a fluvial and relatively warm sub-phase 8000-6250cal yr BP, was canalized, without giving seasonal floods. Sub-phase 6250-3800 is characterized by increased continentality and relative aridization caused reduction of runoff, lowering of the lake level, and enhancement of cryogenic processes. The next phase 3800-2000cal yr BP was more humid. It caused slight revival of fluvial processes and rise of lake level. The last 2000 years climate was more continental and the most arid within the studied period. The lake level and runoff values dropped again, and fluvial activity totally decreased. In contemporary soils aridization is reflected in widely spread Natric features and progressive salinization. Abstract Copyright (2014) Elsevier, B.V.

DOI: 10.1016/j.catena.2013.08.020

14025408 Sapart, C. J. (Utrecht University, Institute for Marine and Atmospheric Research, Utrecht, Netherlands); Boereboom, T.; Rockmann, T.; Niemann, H.; van der Veen, C. and Tison, J. L. Unravel the role of lake ice cover on the methane budget; a multi-proxy analysis [abstr.]: in Goldschmidt abstracts 2013, Mineralogical Magazine, 77(5), p. 2134, 2013. Meeting: Goldschmidt 2013, Aug. 25-30, 2013, Florence, Italy.

Large uncertainties exist on the evolution of the atmospheric methane (CH₄) budget in the future. Concern about possible feedbacks of natural sources in a changing climate is growing, especially concerning the role of thawing of permafrost areas in the Arctic regions. Subarctic lakes are considered as "hotspots" for CH₄ emissions, but the role of the ice cover during the winter period is not well understood to date. Different types of gas bubbles with high CH₄ mixing ratios have been identified in lake ice cover. A recent study revealed that the gas composition of those bubbles depends on, inter alia, the bubble type, the lake depth and the hydrological status of the lakes. Analysing mixing and stable isotope ratios of CH₄ and CO₂ on those bubbles is an efficient tool to identify the mechanisms involved in the release, the oxidation and transport of CH₄ in permafrost lakes and to better constrain the potential influence of lake characteristics. Those analyses together with lipid biomarkers distribution analysis on lake ice samples reveal that different bubble types contain different isotopic signatures and that oxidation of dissolved CH₄ is the most important process determining the isotopic composition of CH₄ in bubbles. This shows that the increased exchange time between gases coming from the sediments and the water column, due to the capping effect of the lake ice cover, reduces the amount of CH₄ released and favours its oxidation into carbon dioxide.

DOI: 10.1180/minmag.2013.077.5.19

14022919 Guo Wei (Jilin University, College of Construction Engineering, Changchun, China); Sun Youhong; Xu Huiwen and Chen Chen. A sampling technology for gas hydrates by borehole bottom freezing [abstr.]: in 34th international geological congress; abstracts, International Geological Congress, Abstracts = Congrès Géologique International, Résumés, 34, p. 74, 2012. compact disc. Meeting: 34th international geological congress, Aug. 5-10, 2012, Brisbane, Queensl., Australia.

The new sampling technology for gas hydrates by borehole bottom freezing includes three key components: sampler by borehole bottom freezing, mud cooling system and low temperature mud system. The sampler for gas hydrates by borehole bottom freezing creating a novel approach to the development of in-situ gas hydrate sample. This technique can significantly reduce the sampling pressure and prevent decomposition of the hydrate samples due to the external cold source which may freeze the hydrate cores on the bottom of borehole. A freezing sample was designed and built based on its thermal-mechanical proper ties and structure. The technique was tested with a trial of core drilling. Results demonstrate that this technique can be applied to obtain freezing samples from the borehole bottom. Mud cooling system is an independent system for reducing the temperature of mud that returns to the surface. It can cool mud rapidly and maintain dynamically the low temperature of mud, and ensure the temperature of the inlet well mud to meet the gas hydrate drilling operation. The mud cooling system has been applied to the drilling engineering in the Qilian mountain permafrost, northwest China, and achieved the gas hydrates in permafrost. Low temperature mud system for NaCl and KCl is developed, whose resistance to the temperature is as low as -20 C. In-situ sampling of gas hydrates can by achieved through combination of that three key components.

14025089 Sanders, Rebecca L. (Princeton University, Department of Geosciences, Princeton, NJ); Sleighter, Rachel L.; Onstott, Tullis C.; Whyte, Lyle G.; Hatcher, Patrick G. and Myneni, Satish C. B. Composition of SOM in the Canadian High Arctic [abstr.]: in Goldschmidt 2012 abstract volume, Mineralogical Magazine, 76(6), p. 2320, 2012. Meeting: Goldschmidt 2012, June 24-29, 2012, Montreal, QC, Canada.

Permafrost underlies one fourth of the Earth's surface and contains approximately half of the global organic carbon (OC) in soils. Thawing and rapid losses of OC in the form of CO₂ and CH₄, associated with warming of arctic regions, raises serious concerns about the stability of OC in permafrost soils and its influence on the biogeochemical cycling in the surrounding Arctic Ocean. The composition of extractable OC in a soil profile collected from the McGill Arctic Research Station on Axel Heiberg Island in the Canadian high Arctic has been characterized using ultrahigh resolution mass spectrometry and nuclear magnetic resonance spectroscopy. The OC in this polar desert is oxygen-poor and highly enriched in lipids, because algae and detrital carbon from surrounding rocks are the main carbon sources. The OC is poor in lignin and protein in the high Arctic soils when compared to soils of other climates because of the lack of vascular plants. In addition, the OC composition of the whole soils was analyzed by carbon K-edge XANES, which indicated that the OC consisted of mostly aliphatic carbon as well as smaller contributions from unsaturated OC, carboxyls, and proteins. Most striking was the absence of oxygenated OC, which is often present as carbohydrates in polar region soils with more vegetation. Such a contrasting composition of OC in Arctic soils may result in carbon losses from climate warming that may disagree with the widely-accepted models based upon the biogeochemistry of temperate soils. Heating experiments are currently underway to investigate how and to what extent the OC composition changes as a function of warming, indicative of how these soils may evolve as a result of climate change. Understanding how recalcitrant this highly aliphatic, oxygen-poor terrestrial carbon is will be critical to identifying its impact on the biogeochemical cycling in the surrounding Arctic Ocean.

URL: http://minmag.geoscienceworld.org/content/76/6/2310.full.pdf+html

14025550 Song Lei (China University of Mining and Technology, School of Mechanics and Civil Engineering State Key Laboratory for Geomechanics and Deep Underground Engineering, Xuzhou, China); Yang Weihao; Huang Jiahui; Li Haipeng and Zhang Xiaojun. GPR utilization in artificial freezing engineering: in GPR for geotechnical engineering (Liu, Lanbo, editor; et al.), Journal of Geophysics and Engineering, 10(3), Paper no. 034004, illus. incl. 2 tables, 44 ref., June 2013. Meeting: 14th international conference on Ground penetrating radar, June 4-8, 2012, Shanghai, China.

To utilize ground penetrating radar (GPR) in artificial freezing engineering (AFE), the electromagnetic parameters (EMP) of frozen soil were measured using a vector network analyser, which showed that the dielectric permittivity and electric conductivity change abruptly at the boundary between the frozen and the non-frozen soil. Then similarity criteria of GPR model experiments were deduced, and GPR laboratory model experiments and field explorations of AFE were carried out. It was found that for AFE, the GPR travel time and profile characters of anomalies in model experiments were similar to those in field explorations, while the amplitude of GPR signals in laboratory model experiments were much stronger than those in field explorations. Numerical simulations were also implemented to analyse the relationship between model experiments and field explorations, which further told us why we could easily find the targets by GPR in the laboratory but not in field explorations. The outputs showed that GPR could be used to detect the thickness of the frozen wall and to find unfrozen soil defects, even though the amplitude of the reflective signals were much weaker than those of laboratory experiments. The research findings have an important theoretical value for AFE and permafrost region engineering, and the deduced GPR similarity criteria could be widely used in other GPR model experiments. Copyright 2013 Sinopec Geophysical Research Institute

DOI: 10.1088/1742-2132/10/3/034004

14027038 Farnsworth, Lauren (Bates College, Department of Geology, Lewiston, ME); Retelle, Michael J.; Christiansen, Hanne and Cohen, Sara Mollie. A geomorphic and sedimentological study of the periglacial processes and environments, Vardeborgsletta, western Spitsbergen, Svalbard [abstr.]: in Geological Society of America, Northeastern Section, 48th annual meeting, Abstracts with Programs - Geological Society of America, 45(1), p. 79, February 2013. Meeting: Geological Society of America, Northeastern Section, 48th annual meeting, March 18-20, 2013, Bretton Woods, NH.

Periglacial environments in today's polar regions are highly susceptible to current and future climate change. In arctic regions, climate has warmed significantly as compared to mid-latitude regions. This study investigates geomorphological and sedimentological evidence of late Holocene changes in Vardeborgsletta, a unique high arctic periglacial landscape situated in karst terrain in western Spitsbergen, Svalbard. Field work was conducted in the summer of 2012 and included geomorphological mapping and investigations of the current status of the active layer of the permafrost and karst hydrologic processes. In addition, two sediment cores were recovered from two lakes, informally named Lake 4 and Lake 7, within this periglacial terrain. Laboratory analyses of the cores shed light on recent changes in climate and in the karst hydrologic system. In Lake 4, field season measurements and geomorphic evidence (raised shorelines, outlet channels and exposed lake floor interbedded with fan-delta deposits) illustrate the dynamic nature of karst and periglacial processes. In Lake 7, the lack of similar geomorphic evidence indicates that lake level has remained stable in recent times. Laboratory analysis conducted on two surface cores (up to 35cm) from Lake 4 and 7 include loss-on-ignition, bulk density, grain size analysis, and plutonium (^239+240Pu) and radiocarbon age determination. In the Lake 7 core, the lower 20 cm interval is a massive organic-rich silt (10 to 18% LOI) overlain by a 15 cm unit (5 to 10% LOI) comprised of alternating minerogenic clay and silt layers, 1 mm to 1 cm thick. In the Lake 4 core, the upper 18 cm of the core consists of a laminated clayey silt unit. This banded unit overlies a massive silt-rich unit. A 2 meter-deep soil pit excavated at the margin of the delta fan on a section of former lake floor exposes alternating clay-rich and silty sand layers, similar to the Lake 4 core stratigraphy. The sediment core and pit stratigraphy likely reflect periodic (seasonal) input from snowmelt and slope processes as well as episodic fluctuations in lake level. The development of a clear understanding of the modern and recent processes shaping the periglacial landscape in the Vardeborgsletta terrain will provide insight to the response of the high arctic periglacial environments to future climate change.

14027039 Ryan-Henry, John (Brown University, Department of Geological Sciences, Providence, RI); Thomas, Elizabeth K.; Huang, Yongsong and Briner, Jason P. A Holocene centennial-scale temperature and precipitation reconstruction for western Greenland using leaf wax and GDGT biomarkers [abstr.]: in Geological Society of America, Northeastern Section, 48th annual meeting, Abstracts with Programs - Geological Society of America, 45(1), p. 79, February 2013. Meeting: Geological Society of America, Northeastern Section, 48th annual meeting, March 18-20, 2013, Bretton Woods, NH.

The Arctic responds strongly and rapidly to climate change. The Greenland Ice Sheet is especially vulnerable, and changes in ice extent there directly impact global sea level. Therefore, researchers are working to understand the climate dynamics which drive ice sheet change - especially at the ice sheet margin. Changes in ice sheet margins over the past 150 years are well documented, but prior to that, records of ice margin changes are not available. We present an ~8000 year climate record from proglacial-threshold lake N3 in western Greenland. We conducted analyses at centennial resolution, examining leaf waxes and branched GDGTs. Leaf waxes - long-chain hydrocarbons that vary compositionally according to environmental factors - are well preserved in lake sediments and have shown considerable promise in the past ten years for reconstructing temperature, precipitation and ecological variability in the lake catchment. We measure chain length distribution, which varies with plant type and therefore reflects changes in catchment ecology, and leaf wax hydrogen isotopes (dD_wax), which are related to precipitation hydrogen isotopes (dD_precip). Due to permafrost, plants do not have access to an extensive groundwater system, so the majority of plant growth uses precipitation as the source water. The apparent fractionation between dD_wax and dD_precip, caused by preferential use of the lighter isotope during biosynthesis, differs between plant species, but is systematic on the catchment-scale. In the Arctic, dD_precip is positively correlated to temperature, so dD_wax can be used to reconstruct surface temperature in the catchment. Likewise, branched GDGTs (glycerol dialkyl glycerol tetraethers), a component of bacterial membranes produced in soils and lakes, vary compositionally with catchment temperature and pH. The MBT index measures the degree of methylation, which correlates positively with air temperature during synthesis, and the CBT index measures cyclization, which correlates positively with soil pH. We compare our paleoclimate reconstruction to reconstructions of Holocene ice sheet behavior, with the goal of better understanding ice sheet response to climate variability. Samples are currently being processed, and will be presented at the meeting.

14023100 Reynard, Emmanuel (Université de Lausanne, Institut de Géographie, Lausanne, Switzerland); Lambiel, Christophe and Lane, Stuart N. Climate change and integrated analysis of mountain geomorphological systems: in Global change, globalization and Swiss geography (Schneider-Sliwa, Rita, editor; et al.), Geographica Helvetica, 67(1-2), p. 5-14, illus. incl. sketch map, 39 ref., 2012. Meeting: 32nd international geographical congress, April 26-28, 2012, Cologne, Germany.

14023101 Hauck, Christian (University of Fribourg, Department of Geosciences, Fribourg, Switzerland); Collet, Claude; Delaloye, Reynald; Hilbich, Christian; Hoelzle, Martin; Huss, Matthias and Salzmann, Nadine. The potential of new measurement and modelling techniques in alpine cryosphere and geomorphology research: in Global change, globalization and Swiss geography (Schneider-Sliwa, Rita, editor; et al.), Geographica Helvetica, 67(1-2), p. 26-37, illus., 51 ref., 2012. Meeting: 32nd international geographical congress, April 26-28, 2012, Cologne, Germany.

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