January 2016 Permafrost Alert
The U.S. Permafrost Association, together with the American Geosciences Institute (AGI), is pleased to provide the following Permafrost Monthly Alerts (PMA). The AGI GeoRef service regularly scans the contents of over 3500 journals in 40 languages from the global geosciences literature, comprised of approximately 345 different sources. In addition to journals, special publications such as papers in proceedings and hard-to-find publications are provided. Each PMA represents a listing of the permafrost-related materials added to GeoRef during the previous month. Where available, a direct link to the publication is included, which provides access to the full document if you or your institution have a current online subscription.
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16015849 Magnin, Florence (Université de Savoie, EDYTEM Lab, Le Bourget-du-Lac, France); Krautblatter, Michael; Deline, Philip; Ravanel, Ludovic; Malet, Emmanuel and Bevington, Alexandre. Determination of warm, sensitive permafrost areas in near-vertical rockwalls and evaluation of distributed models by electrical resistivity tomography: Journal of Geophysical Research: Earth Surface, 120(5), p. 745-762, illus. incl. 1 table, sketch map, 37 ref., May 2015.
Alpine rockwalls with warm permafrost (near 0°C) are the most active rockfall detachment zones in the Mont Blanc massif (MBM, French Alps) with more than 380 recent events. Near-vertical rockwall permafrost is spatially controlled by variations in rock fractures, snow cover, and microtopography. A reliable method to validate the distribution of permafrost in critical and unstable areas does not yet exist. We present seven electrical resistivity tomography (ERT) surveys measured on five near-vertical rockwalls in the MBM from 2012 and 2013 that have been calibrated with measurements on a granite sample in the laboratory. ERT shows consistent measurements of remaining sensitive permafrost relating to inferred temperatures from 0 to -1.5°C. ERT results demonstrate evidence of topographic controls on permafrost distribution and resistivity gradients that appear to reflect crest width. ERT results are compared to two permafrost index maps that use topoclimatic factors and combine effects of thin snow and fractures, where index model spatial resolution is crucial for the validation with ERT. In cryospheric environments, index maps seem to overestimate permafrost conditions in glacial environments. As a consequence, the sensitive areas of permafrost may slightly deviate from the results from distributed models that are only constrained by topoclimatic factors and interpreted with consideration of local fracture and snow conditions. This study demonstrates (i) that the sensitive and hazardous areas of permafrost in near-vertical rock faces can be assessed and monitored by the means of temperature-calibrated ERT and (ii) that ERT can be used for distributed model validation. Abstract Copyright (2015), American Geophysical Union. All Rights Reserved.
16018438 Ronkainen, Tiina M. (University of Helsinki, Environmental Change Research Unit, Helsinki, Finland); Valiranta, Minna; McClymont, Erin; Biasi, Christina; Salonen, Sakari; Fontana, Sonia and Tuittila, Eeva-Stiina. A combined biogeochemical and palaeobotanical approach to study permafrost environments and past dynamics: JQS. Journal of Quaternary Science, 30(3), p. 189-200, illus. incl. 2 tables, sketch map, 66 ref., April 2015.
When investigating past peatland processes and related carbon cycle dynamics, it is essential to identify and separate different peat environments: bogs, fens and permafrost, and their historical plant assemblages. Bog peat layers contain relatively well-preserved plant material for palaeoecological examination, whereas fen and permafrost peats are often highly humified, which in turn constrains reconstructions of past plant assemblages. Here, we analysed the chemical composition of arctic peat plateau plants to create a local reference training-set of plant biomarkers. We then combined palaeobotanical, biogeochemical and chronological analyses to one permafrost peat sequence collected from the East European Russian tundra (67°03'N, 62°57'E) to investigate past peatland dynamics and to evaluate the performance of the biomarker method in a highly decomposed permafrost environment. The results show that the chronologically constrained macrofossil analysis provided most of the essential information about the peatland succession. However, a more robust reconstruction of the past peatland dynamics was achieved by combining palaeobotanical and biogeochemical data sets. The similarity of the lipid biomarker distributions of the arctic and boreal peatland plants also implies that any established modern biomarker training-set of peatland plants could be applied universally to palaeoecological studies on peat sediments. Abstract Copyright (2010), John Wiley & Sons, Ltd.
16008293 Mu Cuicui (Chinese Academy of Sciences, State Key Laboratory of Frozen Soil Engineering, Lanzhou, China); Zhang Tingjun; Wu Qingbai; Zhang Xiankai; Cao Bin; Wang Qingfeng; Peng Xiaoqing and Cheng Guodong. Stable carbon isotopes as indicators for permafrost carbon vulnerability in upper reach of Heihe River basin, northwestern China: in Quaternary research in eastern and central Eurasia; geoarchaeology, glaciation, geomorphology, and natural hazards (Catto, Norm, editor), Quaternary International, 321, p. 71-77, illus. incl. sects., sketch map, 46 ref., February 13, 2014.
To examine the permafrost carbon vulnerability of the Eboling Mountain in the upper reach of Heihe River basin, Qinghai-Tibet Plateau, the distributions of concentrations and d13C values of TOC (total organic carbon), DOC (dissolved organic carbon) and HWC (hot water soluble carbon) with soil depth in permafrost were analyzed. Our results indicated the potential CH4 emission in the soils near the permafrost table and deep permafrost (414-448 cm) with climate warming. The labile carbon (DOC) and microbial biomass carbon (HWC) in deep permafrost (280-350 cm) have been utilized during soil forming processes, with an increase of d13CDOC and d13CHWC values about 3 ppm. The lower d13C values showed that HWC was more easily available for microbial utilization. The d13C values of TOC suggested that C3 plants prevailed on the Eboling Mountain during the last 7000 years. Abstract Copyright (2014) Elsevier, B.V.
16017614 Lüers, J. (University of Bayreuth, Department of Micrometeorology, Bayreuth, Germany); Westermann, S.; Piel, K. and Boike, J. Annual CO2 budget and seasonal CO2 exchange signals at a high Arctic permafrost site on Spitsbergen, Svalbard archipelago: Biogeosciences, 11(22), p. 6307-6322, illus. incl. sketch maps, 90 ref., 2014.
The annual variability of CO2 exchange in most ecosystems is primarily driven by the activities of plants and soil microorganisms. However, little is known about the carbon balance and its controlling factors outside the growing season in Arctic regions dominated by soil freeze/thaw processes, long-lasting snow cover, and several months of darkness. This study presents a complete annual cycle of the CO2 net ecosystem exchange (NEE) dynamics for a high Arctic tundra area at the west coast of Svalbard based on eddy covariance flux measurements. The annual cumulative CO2 budget is close to 0 g C m-2 yr-1, but displays a strong seasonal variability. Four major CO2 exchange seasons have been identified. (1) During summer (snow-free ground), the CO2 exchange occurs mainly as a result of biological activity, with a dominance of strong CO2 assimilation by the ecosystem. (2) The autumn (snow-free ground or partly snow-covered) is dominated by CO2 respiration as a result of biological activity. (3) In winter and spring (snow-covered ground), low but persistent CO2 release occurs, overlayed by considerable CO2 exchange events in both directions associated with high wind speed and changes of air masses and atmospheric air pressure. (4) The snow melt season (pattern of snow-free and snow-covered areas) is associated with both meteorological and biological forcing, resulting in a carbon uptake by the high Arctic ecosystem. Data related to this article are archived at URL: http://www.biogeosciences.net/11/6307/2014/bg-11-6307-2014.pdf">http://doi.pangaea.de/10.1594/PANGAEA.809507.
16016534 Simpson, Jocelyn M. (University of Alaska-Fairbanks, Fairbanks, AK); Darrow, Margaret M.; Huang, Scott L.; Daanen, Ronald P. and Hubbard, Trent D. Investigating movement and characteristics of a frozen debris lobe, south-central Brooks Range, Alaska: Environmental & Engineering Geoscience, Pre-Issue Publication, 49 p., illus. incl. 4 tables, sketch map, 47 ref., 2015.
Frozen debris lobes (FDLs) are large masses of soil, rock, incorporated organic material, and ice moving down permafrost-affected slopes in the south-central Brooks Range, Alaska. In this paper, we focus on FDL-A, which is an impending geohazard to the Dalton Highway, located just under 40 m away from the highway embankment. We present the results of multi-faceted research, including field-based studies, laboratory testing of soil samples, slope stability analysis, and a GIS analysis. Subsurface instrumentation indicates that major movement of FDL-A occurs in a shear zone 20.6 to 22.8 m below the ground surface, with temperature-dependent internal flow as a secondary movement mechanism. Surface measurements show an overall average rate of movement of 1.2 cm per day, which is an increase over historic rates. The slope stability analysis required a back analysis to determine soil strength parameters at failure, resulting in cohesion values between 43 to 53 kPa and friction angles between 10° and 16°. The modeling results indicated a high sensitivity to pore water pressure and cohesion. This is critical since the melting of massive ice and thawing of frozen soil will increase pore water pressure and lower shear strength, resulting in the acceleration of FDL-A towards the Dalton Highway. The GIS analysis also provided insight into the movement and instability of FDL-A, and provided groundwork for a GIS protocol to examine catchment and lobe features of all FDLs along the highway corridor.
16008423 He Jianglin (Chengdu Institute of Geology and Mineral Resources, Chengdu, China); Wang Jian; Tan Fuwen; Chen Ming; Li Zhongxiong; Sun Tao; Wang Pingkang; Du Baiwei and Chen Wenbin. A comparative study between present and palaeo-heat flow in the Qiangtang Basin, northern Tibet, China: Marine and Petroleum Geology, 57, p. 345-358, illus. incl. 4 tables, geol. sketch map, 60 ref., November 2014.
The Qiangtang Basin is a significant prospective area for hydrocarbon and gas hydrate resources in the Tibetan Plateau, China. However, relatively little work has been performed to characterise heat flow in this basin, which has restricted petroleum and gas hydrate exploration. In this study, we compare present and palaeo-heat flow in the Qiangtang Basin to provide information on geothermal regime, hydrocarbon generation and permafrost that is necessary for further petroleum and gas hydrate exploration. We base our study on temperature data from a thermometer well, thermal conductivity tests, vitrinite reflectance data, homogenisation temperature data from fluid inclusions, stratigraphic information and a time-independent modelling approach. Our results indicate that in the central Qiangtang Basin, the present thermal gradient is approximately 15.5°C/km, and heat flow is approximately 46.69 mW/m2. Heat flow in the Qiangtang Basin is not relatively stable since the Early Jurassic, as previous research has suggested, and it is generally decreasing with time. Additionally, there is a clear difference between the hottest thermal regime of the southern and northern Qiangtang Depressions during Cretaceous to Pleistocene time. In the southern Qiangtang Depression, the palaeogeothermal gradient is approximately 32.0 °C/km, and palaeo-heat flow is approximately 70 mW/m2. However, in the northern Qiangtang Depression, the palaeogeothermal gradient exceeds 81.8 °C/km, and palaeo-heat flow is greater than 172.09 mW/m2. The high thermal regime in the northern Qiangtang Depression is driven mainly by hydrothermal convection. Gas reservoirs are possible targets for hydrocarbon exploration in this depression. Currently, the northwestern part of the northern Qiangtang Depression is the most favourable area for gas hydrate exploration in the Qiangtang Basin. Abstract Copyright (2014) Elsevier, B.V.
16011224 Abaturova, I. V. (Ural State Mining University, Yekaterinburg, Russian Federation) and Gryaznov, O. N. Inzhenerno-geologicheskiye usloviya mestorozhdeniy Urala v skal'nykh massivakh [Engineering geological conditions in mineral deposits in the Urals]: Izvestiya Vysshikh Uchebnykh Zavedeniy. Gornyy Zhurnal, 2014(6), p. 160-168 (English sum.), illus. incl. 2 tables, 8 ref., 2014.
The position of mineral deposits of the Urals of various geological and industrial types in rocks of structural and formational megazones, their belonging to the metallogenic sub-provinces, zones and subzones are considered. Natural and technical systems of mineral deposits as a structured interaction area of the rock mass deposits and mining facilities are characterized; modalities of the interaction area and their components: physical and geographical conditions (climate, biota, topography, hydrology); geological and structural conditions (tectonic features, occurrence of rocks); lithological and petrographic conditions (genesis, age, composition and properties of rocks); permafrost-hydrogeological conditions (types of groundwater, frozen state of rocks); geodynamic conditions (stress state, geological and mining-geological processes). Mining facilities (quarry, underground mining) include: type of facility, method of construction, construction of excavation. Deposits are differentiated by the complexity of geotechnical conditions of their development into three groups--simple, medium and difficult. The features of the development of mineral deposits of varying complexity in open pit and underground mining were considered.
16017307 Oldenborger, Greg A. (Geological Survey of Canada, Ottawa, ON, Canada) and LeBlanc, Anne-Marie. Capacitive resistivity inversion using effective dipole lengths for line antennas: Journal of Applied Geophysics, 98, p. 229-236, illus. incl. sects., sketch map, 26 ref., November 2013.
Non-contacting capacitively-coupled resistivity (CCR) surveys find application in permafrost investigations and investigations over engineered surfaces. However, we observe discrepancies between line-antenna CCR data and galvanic resistivity (GR) data. Inverse models recovered from the different data types exhibit differences in both resistivity magnitude and structure. We apply and test the concept of effective dipole length for line-antenna CCR data collected over permafrost terrain in Iqaluit, Nunavut. We compare inversions of corrected CCR data to the GR counterpart. Results show that correcting CCR data with an effective dipole length of 80% of the physical antenna length results in a resistivity model most in accordance with the GR model. After correction, the CCR model does not precisely emulate the GR model; potential sources of remaining discrepancy are incomplete representation of the line-antenna nature of the CCR data and the realities of field data acquisition including significantly different noise levels and the potential violation of CCR operating conditions. Abstract Copyright (2013) Elsevier, B.V.
16017277 Selroos, Jan-Olof (Swedish Nuclear Fuel and Waste Management Company, Stockholm, Sweden); Cheng, Hua; Painter, Scott and Vidstrand, Patrik. Radionuclide transport during glacial cycles; comparison of two approaches for representing flow transients: in Coupled physical and chemical transformations affecting the performance of geosystems (Holländer, Hartmut M., editor; et al.), Physics and Chemistry of the Earth (2002), 64, p. 32-45, illus. incl. 2 tables, sketch map, 34 ref., 2013.
The effect of future, transient ice sheet movement and permafrost development on transport of radionuclides from a proposed repository site is investigated using numerical groundwater flow and radionuclide transport modelling. Two different transport approaches are compared, both utilizing groundwater flow simulations of future climate conditions. The first transport approach uses steady-state particle trajectories representing temperate climate conditions, but modifies the transport velocity along the trajectories according to the changing climate. The second approach is pseudo-transient by performing particle tracking in each individual flow field representing a given time epoch. Two different climate sequences are analyzed. First, a simplified sequence is assessed in order to understand if the two different transport approaches yield significantly different breakthrough characteristics. Second, a sequence representing conditions relevant for real safety assessment applications is considered. Results indicate that the transport approach using fixed trajectories tends to significantly over predict breakthrough during permafrost conditions relative to the pseudo-transient approach. The major difference between the two approaches is related to discharge locations. The fixed trajectory approach yields discharge locations constant in time whereas the pseudo-transient approach is characterized by discharge centres moving in time according to the different climate conditions. Abstract Copyright (2013) Elsevier, B.V.
16008993 Rasanen, Matti E. (University of Turku, Department of Geography and Geology, Turku, Finland); Huitti, Janne V.; Bhattarai, Saroj; Harvey, Jerry, III and Huttunen, Sanna. The SE sector of the middle Weichselian Eurasian ice sheet was much smaller than assumed: Quaternary Science Reviews, 122, p. 131-141, illus. incl. sketch map, 51 ref., August 15, 2015.
Quaternary climatic and glacial history must be known in order to understand future environments. Reconstructions of the last Weichselian glacial cycle 117,000-11,700 years (kyr) ago propose that S Finland, adjacent Russia and the Baltic countries in the SE sector of the Eurasian Ice Sheet (EIS), were glaciated during the Middle Weichselian time [marine isotope stage (MIS) 4, 71-57 kyr ago] and that this glaciation was preceded in S Finland by an Early Weichselian interstadial (MIS 5c, 105-93 kyr ago) with pine forest. We apply glacial sequence stratigraphy to isolated Late Pleistocene onshore outcrop sections and show, that these events did not take place. The one Late Weichselian glaciation (MIS 2, 29-11 kyr ago) was preceded in S Finland by a nearly 90 kyr non-glacial period, featuring tundra with permafrost and probably birch forest. Our new Middle Weichselian paleoenvironmental scenario revises the configuration and hydrology of the S part of EIS and gives new setting for the evolution of Scandinavian biota. If future development during the coming glacial cycle proves to be similar, the high-level nuclear waste stored in the bedrock of SW Finland should be located deeper than currently planned, i.e. below any possible future permafrost. Abstract Copyright (2015) Elsevier, B.V.
16018499 Gruszka, Beata (Adam Mickiewicz University, Institute of Geology, Poznan, Poland) and Terpilowski, Slawomir. Sedimentary record of the younger Saalian ice margin stagnation in eastern Poland; development of a regular pattern of glaciolacustrine kames: Geografiska Annaler. Series A: Physical Geography, 97(2), p. 279-298, illus. incl. sect., 1 table, sketch map, 86 ref., June 2015.
Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique regular pattern. Three representative morphological kame types were chosen for detailed sedimentological analyses, specifically: isolated, isometric mounds; isolated, elongated hills; and branching ridges. All types comprised fine-grained sandy and sandy/silty deposits. Lithofacies analysis resulted in the distinction of several lithofacies associations. Associations dominated by medium- or large-scale, massive or horizontally laminated sands are interpreted as proximal subaqueous fans; associations dominated by medium- or small-scale lithofacies of ripple-drift cross-laminated sand are interpreted as distal subaqueous fans; and those dominated by sandy/silty, silty or silty/clayey lithofacies with horizontal lamination are interpreted as lake bottomsets. Rates of sediment accumulation appear to have been fast, resulting in syndepositional and metadepositional deformation structures of two types: water-escape structures, and slumps on subaqueous slopes. After the ice-walled lake basins filled with sediment, glaciofluvial erosion and deposition alternated, resulting in erosional channels of up to 1 m deep, later filled with gravel or gravely sand. The results indicate that kames developed in a supraglacial environment within a topography of ice-cored moraines containing ice-walled lakes that persisted due to the presence of permafrost. Pauses during retreat of the ice walls resulted in ice-contact deformations at the edges of the kames. Kame formation is therefore consistent with a continental climate and this may explain the increased abundance of this type of kame system in Eastern Europe. Abstract Copyright (2014), Swedish Society for Anthropology and Geography.
16018503 Mahaney, William C. (Quaternary Surveys, Thornhill, ON, Canada) and Hancock, R.G.V. Holocene soils/paleosols in the Okstindan Mountains, Nordland; stratigraphy and extractable Fe and Al: Geografiska Annaler. Series A: Physical Geography, 97(2), p. 355-373, illus. incl. 5 tables, geol. sketch maps, 61 ref., June 2015.
A chronosequence of surface and buried soils in moraines and outwash, ranging in age from Middle to Late Holocene, i.e., Little Ice Age, and forming under alpine and subalpine vegetation in the Okstindan Mountains of central-north Norway (66°N) (Oksskolten) was studied to determine if topographic/stratigraphic setting, weathering characteristics, soil/paleosol properties, SEM/EDS analysis, and extractable Fe and Al could be used to elucidate information on paleoenvironment and age. The geochemical data previously published and geological mapping by the Norwegian Geological Survey indicate a uniform parent material in these profiles. Slight geochemical anomalies of higher U, Th and Br in organic-rich horizons are related to vegetation and/or higher water content at various times, confirmed by extractable Fe evidence. The data interpretation also shows that extractable Fe, principally Feo, is useful in identifying previous perched water tables, possibly generated by permafrost. The activity ratio of Feo/Fed (oxalate to dithionite) and the ratio Fed/Fet (dithionite to total Fe) appear useful in distinguishing older from younger soils on the basis of the conversion of ferrihydrite to goethite+hematite. Pyrophosphate extracts, proved useful in determining movement of organically bound Al, and showed a pronounced difference between the alpine and subalpine environments. Oxalate-extractable and dithionite-extractable Al proved of little value in relative age determination, presumably because sodium dithionite does not extract all crystalline Al. Abstract Copyright (2014), Swedish Society for Anthropology and Geography.
16018443 Liu Xiangjun (Chinese Academy of Sciences, Qinghai Institute of Salt Lakes, Xining, China); Lai Zhongping; Madsen, David and Zeng Fangming. Last deglacial and Holocene lake level variations of Qinghai Lake, north-eastern Qinghai-Tibetan Plateau: JQS. Journal of Quaternary Science, 30(3), p. 245-257, illus. incl. sects., strat. cols., 1 table, sketch map, 91 ref., April 2015.
Qinghai Lake is of significance for paleoclimate research because it lies in a pivotal region that is influenced by both the mid-latitude Westerlies and the low-latitude Asian summer monsoon (ASM). Most published lake level histories of Qinghai Lake are interpreted from drill-core proxies. Here we combine geomorphic shoreline investigations with optically stimulated luminescence dating to constrain lake level variations since the last deglacial. The results indicate that two periods of highstands occurred during the last deglacial (~16-14.9 and ~12.6-12.2 ka), and that lake levels were 6-7.4 m higher than at present. Lake levels dropped abruptly during the Younger Dryas, and were generally low with frequent fluctuations during the early Holocene. Qinghai Lake reached its highest Holocene level, 9.1 m higher than modern, at ~5 ka, and has regressed during the past 2 ka. We propose that high lake levels during the last deglacial were due mainly to melting glacial and permafrost waters, supplemented by enhanced Westerlies precipitation and decreased evaporation during Heinrich Event 1 (~16-14.9 ka) and increased ASM rainfall during the Bolling-Allerod warm period (~14-12 ka). Lake level fluctuations during the Holocene were generally in accordance with moisture variations in the marginal monsoon zones of inland China. Abstract Copyright (2010), John Wiley & Sons, Ltd.
16017628 Heiri, Oliver (University of Bern, Institute of Plant Sciences, Bern, Switzerland); Koinig, Karin A.; Spötl, Christoph; Barrett, Sam; Brauer, Achim; Drescher-Schneider, Ruth; Gaar, Dorian; Ivy-Ochs, Susan; Kerschner, Hanns; Luetscher, Marc; Moran, Andrew; Nicolussi, Kurt; Preusser, Frank; Schmidt, Roland; Schoeneich, Philippe; Schwörer, Christoph; Sprafke, Tobias; Terhorst, Birgit and Tinner, Willy. Palaeoclimate records 60-8 ka in the Austrian and Swiss Alps and their forelands: in Dating, synthesis, and interpretation of palaeoclimatic records and model-data integration; advances of the INTIMATE project (INTegration of Ice core, Marine and TErrestrial records, COST Action ES0907) (Rasmussen, Sune Olander, editor; et al.), Quaternary Science Reviews, 106, p. 186-205, illus. incl. 1 table, sketch map, 155 ref., December 15, 2014.
The European Alps and their forelands provide a range of different archives and climate proxies for developing climate records in the time interval 60-8 thousand years (ka) ago. We review quantitative and semi-quantitative approaches for reconstructing climatic variables in the Austrian and Swiss sector of the Alpine region within this time interval. Available quantitative to semi-quantitative climate records in this region are mainly based on fossil assemblages of biota such as chironomids, cladocerans, coleopterans, diatoms and pollen preserved in lake sediments and peat, the analysis of oxygen isotopes in speleothems and lake sediment records, the reconstruction of past variations in treeline altitude, the reconstruction of past equilibrium line altitude and extent of glaciers based on geomorphological evidence, and the interpretation of past soil formation processes, dust deposition and permafrost as apparent in loess-palaeosol sequences. Palaeoclimate reconstructions in the Alpine region are affected by dating uncertainties increasing with age, the fragmentary nature of most of the available records, which typically only incorporate a fraction of the time interval of interest, and the limited replication of records within and between regions. Furthermore, there have been few attempts to cross-validate different approaches across this time interval to confirm reconstructed patterns of climatic change by several independent lines of evidence. Based on our review we identify a number of developments that would provide major advances for palaeoclimate reconstruction for the period 60-8 ka in the Alps and their forelands. These include (1) the compilation of individual, fragmentary records to longer and continuous reconstructions, (2) replication of climate records and the development of regional reconstructions for different parts of the Alps, (3) the cross-validation of different proxy-types and approaches, and (4) the reconstruction of past variations in climate gradients across the Alps and their forelands. Furthermore, the development of downscaled climate model runs for the Alpine region 60-8 ka, and of forward modelling approaches for climate proxies would expand the opportunities for quantitative assessments of climatic conditions in Europe within this time-interval. Abstract Copyright (2014) Elsevier, B.V.
16018500 Kerguillec, Riwan (University of Nantes, Geographic Institute, Nantes, France). Characteristics and altitudinal distribution of periglacial decay phenomena in the massif of Rondane, central Norway: Geografiska Annaler. Series A: Physical Geography, 97(2), p. 299-315, illus. incl. 3 tables, sketch map, 76 ref., June 2015.
The Norwegian massif of Rondane is part of the Scandes Mountains and is subject to polar, oceanic and continental influences. Because of its climatic context and its quartzitic structure, the massif has one of the thickest functional periglacial belts in Europe (1200 m). This belt is not fixed considering its translation in altitude since the end of the Little Ice Age. This mobility is continuing and involves periglacial decay dynamics which are revealed by numerous and various periglacial forms in the field. Because of their frequency in the massif and also their sensitivity to climate fluctuations, earth patches and small non-sorted circles have a diagnostic value for current periglacial climate fluctuations. The major aim of this study is to propose several indicators of this periglacial decay and to highlight its consequences on periglacial belt mobility because these landforms enable the delimitation of a critical belt of decay in the massif. Abstract Copyright (2014), Swedish Society for Anthropology and Geography.
16011368 Zhang Yuzhi (Shijiazhuang Tiedao University, Structural Health Monitoring and Control Key Laboratory of Hebei Province, Shijiazhuang, China); Du Yanliang and Sun Baochen. Predicting frost penetration of high-speed railway subgrade in seasonally frozen regions based on empirical method: International Journal of Earth Sciences and Engineering, 7(3), p. 1118-1126, illus. incl. 8 tables, 18 ref., June 2014.
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16014455 Evans, Sarah G. (University of Colorado at Boulder, Department of Geological Sciences, Boulder, CO); Ge, Shemin and Liang Sihai. Analysis of groundwater flow in mountainous, headwater catchments with permafrost [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 31, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.
Headwater catchments have a direct impact on the water resources of downstream lowland regions as they supply freshwater in the form of discharging groundwater. Often, these mountainous catchments contain expansive permafrost that may alter the natural topographically-controlled groundwater flow system. As permafrost could degrade with climate change, it is critical to understand the effect of permafrost on groundwater flow in headwater catchments. This study characterizes groundwater flow in mountainous headwater catchments and evaluates the effect of permafrost on groundwater movement using a three-dimensional, finite element, hydrogeologic model. The model is applied to a representative headwater catchment on the northern Qinghai-Tibet Plateau, China. Results from the model simulations indicate that groundwater contributes significantly to streams in the form of baseflow and the majority of groundwater flow is from the shallow aquifer above the permafrost, disrupting the typical topographically-controlled flow pattern observed in most permafrost-free headwater catchments. Under a warming scenario where mean annual temperature is increased by 2°C, the areal extent of permafrost in the catchment decreases by 28%. With this reduction in permafrost extent, groundwater contribution to streamflow may increase three-fold. These findings suggest that, in headwater catchments, permafrost has a large influence on groundwater flow and stream discharge. Increased annual temperatures will increase groundwater discharge to streams, which has implications for ecosystem health and the long-term availability of water resources to downstream regions.
16017692 Bense, V. (University of East Anglia, Norwich, United Kingdom); Binley, A. M.; Keating, K.; Van Dam, R. L.; Christiansen, Hanne H.; Cohen, Sara and McGuffy, C. Magnetotelluric and surface nuclear magnetic resonance measurements of regional and local variability of deep saline permafrost in Adventdalen, Svalbard [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS34A-04, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
In most Arctic areas the interplay between permafrost and parameters such as climate variability and geological history is not well understood or documented. Nevertheless, knowledge on the thermal state of permafrost, its thickness and ice/water content is crucial for a credible assessment of the impacts of surface warming on a suite of environmental processes such as groundwater flow to riverbeds and the release of methane from areas of degrading permafrost. We carried out geophysical surveys using non-invasive Magnetotelluric (MT) and Surface Nuclear Magnetic Resonance (SNMR) techniques to map permafrost occurrence in Adventdalen, Svalbard, a river valley in a typical coastal Arctic landscape. MT, which is sensitive to changes in the electrical conductivity and can be used to distinguish saline, fresh, and frozen soils, was used to determine the total thickness of permafrost (potentially several 100s of meters). SNMR, which is directly sensitive the volume of liquid water, was used to determine the unfrozen water content and the heterogeneity of permafrost at depths of up to ~100 m. We collected measurements in transects across and along the valley which is filled with Holocene estuarine sediments. observations suggest that permafrost thickens substantially to up to several hundreds of meters along the ~12 km long transect from the coastal area inland. The electrical resistivities observed are relatively low (~200-400 Wm) when compared to permafrost environments in Alpine settings, which is most likely attributed to a high salinity of pore waters in our study area. In the parts of the valley above the marine limit (~70 m above sea-level) SNMR did not detect any unfrozen water content. However, closely spaced SNMR transects across the valley several kilometers from the coast show a substantial signal, potentially due to unfrozen water content in supra-permafrost taliks near the main river channel. This is the first study to illustrate the ability of combining MT and SNMR data to map permafrost characteristics in saline environments. Combining these geophysical measurements with auxiliary data on the pore water salinities, temperature and the geological makeup of the study area will allow a thorough determination of ice-content and thermal state of deep permafrost in this coastal permafrost environment.
16017694 Douglas, Thomas A. (U. S. Army Cold Regions Research and Engineering Laboratory Alaska, Fairbanks, AK); Bjella, Kevin; Hiemstra, Christopher A.; Newman, Stephen D.; Anderson, John; Edwards, Jarrod; Arcone, Steven A.; Wagner, Anna M.; Barbato, Robyn; Berkowitz, Jacob and Deeb, Elias J. Integration of geophysical, ground surface, and remote sensing methods to identify ice features in discontinuous permafrost near Fairbanks, Alaska [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS34A-06, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Ground ice features such as ice wedges, segregation ice, and thermokarst cave ice are present in the subsurface in a variety of spatial scales and patterns. Accurately identifying the character and extent of these ice features in permafrost terrains allows engineers and planners to cost effectively create innovative infrastructure designs to withstand the changing environment. We are assembling a holistic view of how a variety of surficial and standoff geophysical measurements can be combined with classic ground based measurements to delineate subsurface permafrost features. We are combining horizontal geophysical measurements; borehole mapping; multispectral and radar remote sensing; airborne and ground-based LiDAR; snow, soil, and vegetation mapping; and subsurface thermal measurements and modeling at three field sites in discontinuous permafrost of Interior Alaska. Our sites cross transects representing upland and lowland permafrost and a variety of soil and vegetation compositions. With our measurements we identified and mapped a 300 meter wide swath of ice rich frozen peat at one of our lowland field sites. The high ice content was confirmed with borehole measurements. This ice rich permafrost region yields higher electrical resistivity values than the nearby permafrost and is associated with anomalously low seasonal thaw depths compared to other sites nearby. Surface soils in the ice rich region have high soil moisture contents, low redox potential (30-100 mV), and elevated soil microbial activity. The ice rice region yields low phase changes from paired interferometric synthetic aperture radar measurements collected in late spring and late summer. One interpretation of this result is that the ice rich area experiences minimal summer season subsidence. Taken in total, our results suggest the ice rich peat region has distinct surface signatures and subsurface geophysical characteristics that may be extrapolated to other areas to identify ice rich permafrost in the subsurface.
16008764 Foley, N. (University of California Santa Cruz, Santa Cruz, CA); Tulaczyk, S. M.; Auken, Esben and Mikucki, J. Shallow sub-permafrost groundwater systems in a buried fjord; Taylor Valley, Antarctica [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS31A-3920, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
The McMurdo Dry Valleys (MDV), Antarctica, represent a unique geologic setting where permanent lakes, ephemeral streams, and subglacial waters influence surface hydrology in a cold polar desert. Past research suggested that the MDV are underlain by several hundreds of meters of permafrost. Here, we present data collected from an Airborne EM (AEM) resistivity sensor flown over the MDV during the 2011-12 austral summer. A focus of our survey was over the Taylor Glacier where saline, iron-rich subglacial fluid releases at the glacier snout at a feature known as Blood Falls, and over Taylor Valley, where a series of isolated lakes lie between Taylor Glacier and the Ross Sea. Our data show that in Taylor Valley there are extensive areas of low resistivity, interpreted as hypersaline brines, beneath a relatively thin layer of high resistivity material, interpreted as dry- or ice-cemented permafrost. These hypersaline brines remain liquid at temperatures well below 0°C due to their salinity. They appear to be contained within the sedimentary fill deposited in Taylor Valley when it was still a fjord. This brine system continues up valley and has a subglacial extension beneath Taylor Glacier, where it may provide the source that feeds Blood Falls. By categorizing the resistivity measurements according to surficial land cover, we are able to distinguish between ice, permafrost, lake water, and seawater based on characteristic resistivity distributions. Furthermore, this technique shows that areas of surface permafrost become increasingly conductive (brine-filled) with depth, whereas the large lakes exhibit taliks that extend through the entire thickness of the permafrost. The subsurface brines represent a large, unstudied and potentially connected hydrogeologic system, in which subsurface flows may help transfer water and nutrients between lakes in the MDV and into the Ross Sea. Such a system is a potential habitat for extremophile life, similar to that already detected in the Blood Falls outflow, and may serve as a terrestrial analogue to potential extraterrestrial habits, where liquid surface waters are not expected to exist.
16008767 Grebenets, V. I. (Lomonosov Mosocw State University, Moscow, Russian Federation); Kerimov, Ali G.; Shiklomanov, N. I.; Streletskiy, D. A.; Shkoda, V. S. and Anduschenko, F. D. Thermal state of permafrost in urban environment under changing climatic conditions [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS31A-3923, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Large industrial centers on permafrost are characterized by a set of geocryological conditions different from natural environment. Thermal state of foundations on permafrost in areas of economic development depends on climate trends and upon technogenic impacts, such as type of impact, area of facility, permafrost temperature and duration of the technogenic pressure. Technogenic degradation of permafrost is evident in most urban centers on permafrost leading to deterioration of geotechnical environment and particularly foundations of buildings and structures. This situation is exacerbated by climate warming in such cities as Vorkuta, Chita, Nerungry, Salekhard and others where temperature rises at a rate of 0.4-1.2°C/decade over the last 40 years. To evaluate impact of climate warming and technogenic factors on permafrost temperature regime and foundation bearing capacity we compared five facilities in Norilsk, the largest city on permafrost. The facilities were selected to represent different parts of the town, different ages of built-up environment and were located in different permafrost and lithological conditions. We found a leading role of technogenic factors relative to climatic ones in dynamics of thermal state of permafrost in urban environment. Climate warming in Norilsk (0.15°C/decade) was a small contributor, but gave an additional input to deterioration of geotechnical environment on permafrost. At the same time, implementation of engineering solutions of permafrost temperature cooling (such as crawl spaces) result in lowering of permafrost temperature. Field surveys in Yamburg showed that under some facilities permafrost temperature decreased by 1-1.5°C over the last 15 years despite pronounced in the region climate warming of 0.5°C/decade. This shows that despite deterioration of permafrost conditions in the most Arctic regions due to technogenic pressure and climate warming, implementation of adequate engineering solutions allows stabilization of permafrost thermal regime.
16017689 Minsley, B. J. (U. S. Geological Survey, Denver, CO); Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N. J.; Smith, B. D.; Voss, C. I.; Walsh, David O.; Walvoord, M. A. and Wylie, B. K. Mapping permafrost with airborne electromagnetics [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS34A-01, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1 m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.
16008766 Zhang, Yu (Canada Center for Remote Sensing, Ottawa, ON, Canada). A new approach to mapping permafrost and change incorporating uncertainties in ground conditions and climate projections [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS31A-3922, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Spatially detailed information on permafrost distribution and change with climate is important for land-use planning, infrastructure development and environmental assessments. However, the required soil and surficial geology maps in the North are coarse, and projected climate scenarios vary widely. Considering these uncertainties, we propose a new approach to mapping permafrost distribution and change by integrating remote sensing data, field measurements, and a process-based model. Land-cover types from satellite imagery are used to capture the general land conditions and to improve the resolution of existing permafrost maps. For each land-cover type, field observations are used to estimate the probability of different ground conditions. A process-based model is used to quantify the evolution of permafrost for each ground condition under three representative climate scenarios (low, medium and high warming). From the model results, the probability of permafrost occurrence and the most likely permafrost conditions are determined. We apply this approach at 20 m resolution to a large area in Northwest Territories, Canada. Mapped permafrost conditions are in agreement with field observations and other studies. The data requirements, model robustness and computation time are reasonable, and this approach may serve as a practical means to mapping permafrost and changes at high resolution in other regions.
16018817 Brand, Uwe (Brock University, Department of Earth Sciences, Ste. Catharines, ON, Canada); Blamey, Nigel J. F.; Griesshaber, Erika; Posenato, Renato; Angiolini, Lucia; Azmy, Karem; Farabegoli, Enzo and Came, Rosemarie E. Methane hydrate; killer cause of Earth's greatest mass extinction [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 209, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.
The cause for the end Permian mass extinction, the greatest challenge life on Earth faced in its geologic history, although still hotly debated it bears an important message for humanity. The most significant marker of this event is the negative d13C shift and rebound recorded in marine carbonates with a duration ranging from 2000 to 19,000 years. Leading cause for the event are Siberian trap volcanism and its emission of greenhouse gases with consequent global warming, but other leading contenders are oceanic anoxia and acidification. We present measurements of gases vaulted in shell calcite of end Permian brachiopods and whole rock, documenting significant differences in normal atmospheric equilibrium concentration (NAEC) of gases between modern and end Permian seawaters. The gas composition recorded in end Permian brachiopod gas-inclusions reflects dramatically higher seawater methane contents leading up to the event. Initial global warming of 8 to 11°C sourced by isotopically light carbon dioxide from volcanic emissions triggered the sudden release of methane from permafrost and shelf sediment hydrate. Consequently, the huge quantities of methane emitted into the atmosphere and the oceans accelerated global warming and marked the negative d13C spike observed in marine carbonates marking the onset of the biggest mass extinction in Earth history. The rapidity of the methane emission lasting from several years to thousands of years was tempered by the equally rapid oxidation of the atmospheric and oceanic methane that gradually reduced its warming potential but not before global warming had reached levels lethal to most life on land and in the oceans. Based on measurements of gases trapped in biogenic and abiogenic calcite, the release of methane (of ~8-28% of total C stored) from permafrost and shelf sediment hydrate was the ultimate source and cause for the dramatic life-changing global warming (GMAT>34°C) and oceanic (negative carbon isotope excursion) changes observed during the end Permian. Global warming triggered by the exorbitant release of carbon dioxide may be catastrophic, but the subsequent release of methane hydrate may be apocalyptic. The end Permian may have an important lesson for humanity regarding the issue of global warming and climate change it faces today.
16008763 Arcone, Steven A. (U. S. Army Cold Regions Research and Engineering Laboratory, Hanover, NH). Interpretation of stratified fill, frost depths, water tables, and massive ice within multi-frequency ground-penetrating radar profiles recorded beneath highways in interior Alaska [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS31A-3919, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Road Radar generally refers to ground-penetrating radar (GPR) surveys intended to investigate pavement construction using pulses centered above 1 GHz. In interior Alaska thick sand and gravel grading and its frozen state by late winter generally afford up to 10 m of signal penetration at lower frequencies. Consequently, this penetration potentially allows identification of pavement issues involving frost heave and thaw settlement, while the smooth surface allows assessment of GPR performance in permafrost areas under ideal survey conditions. Here I discuss profiles using pulse center frequencies from 50 to 360 MHz, recorded over sections of the Steese and Elliott Highways within and just north of Fairbanks, respectively, and of the Tok Highway near Glennallen. Construction fill is easily recognized by its stratification; where marginally present along the Elliott it is replaced by steeply dipping horizons from the underlying schist. The frost depth and water table horizons are recognized by phase attributes of the reflected pulse, as dictated by the contrasts present in dielectric permittivity, their relative depths, and their continuity. Undulating stratification in the sand and gravel fill indicates thaw settlement, as caused by the melting of buried massive ice. The Tok section reveals the top and likely the bottom of massive ice. Generally, signal penetration is greatly reduced beneath the water table and so the highest resolution, at 360 MHz, covers all horizons. There is rare evidence of a permafrost table because it is most likely masked or nearly coincident with the water table. Permafrost penetration in frozen silts is a long-standing problem for GPR, for which I discuss a possible cause related to Maxwell-Wagner dielectric relaxation losses associated with unfrozen water.
16018164 Coyle, Brian J. (Honeywell Technology Solutions, Anchorage, AK); Lundgren, Mike and Busby, R. W. Development of an ultra-light multipurpose drill and tooling for the transportable array in Alaska [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract S13C-4476, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Over the next four years the EarthScope Transportable Array (TA) will install approximately 250 to 275 broadband seismic stations in Alaska and Western Canada. The station plans build on recent developments in posthole broadband seismometer design and call for sensors to be installed in boreholes 7 inches diameter, from 1 to 5 meters deep. These boreholes will be lined with PVC or steel casing, grouted in place. The proposed station locations are in a grid-like pattern with a nominal spacing of 85 km. Since most of these locations will only be accessible by helicopter, it was necessary to develop an ultra-light drilling system that could be transported to site in one sling load by a high performance light helicopter (i.e. AS350B2 or Bell 407) and still be able to drill the variety of ground conditions we expect to encounter. In the past year we have developed a working prototype, gasoline-hydraulic drill rig that can be configured to run auger, diamond core or DTH tools, and weighs <1,300 lbs, including tooling. We have successfully drilled over 30 boreholes with this drill, including 12 for TA installations in Alaska and 13 at the Pinon Flat Observatory for testing sensor performance and placement techniques. Our drilling solution comprises: - Hydraulic system using a variable flow pump with on-demand load sensing valves to reduce the engine size needed and to cut down on heat build-up; - Rotation head mounting system on the travelling block to enable quick change of drilling tools; - Low speed, high torque rotation head for the auger, and an anchoring system that enables us to apply up to 5,000 lbs downforce for augering in permafrost; - Custom DTH that can run on low air pressure and air flow, yet is still robust enough to drill a 7 inch hole 2.5 meters through solid rock; - One-trip casing advance drilling with the DTH, steel casing is loaded at the start of drilling and follows the drill bit down; - Grout-through bottom caps for sealing the borehole casing and cementing it in place. Our next step is to build a dedicated DTH drilling system that will be light enough to mobilize to sites in one helicopter sling, including an air compressor. This rig is currently on the drawing board and we expect to build it this winter for field testing in the spring.
16017690 Dugan, Hilary (University of Illinois at Chicago, Chicago, IL); Mikucki, J.; Auken, Esben; Tulaczyk, S. M.; Virginia, Ross A.; Schamper, Cyril; Sorensen, Kurt; Doran, P. T. and Foley, N. Aerial EM survey reveals groundwater systems beneath Taylor Valley, Antarctica [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS34A-02, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
The extent of groundwater and its potential habitability in the ice-free regions and along the coastal margins of Antarctica is poorly understood. Here we report on an airborne transient electromagnetic survey in Antarctica, which for the first time produced extensive imagery of subsurface resistivity in Taylor Valley, an ice-free margin of the Ross Sea. Wide zones of low subsurface resistivity were detected that are inconsistent with the typical high resistivity of glacier ice or dry permafrost. These results are interpreted as an indication that water, with sufficiently high solute content to remain unfrozen well below 0°C, temperatures considered within the range suitable for microbial life. The inferred subsurface brines are widespread and form two isolated groundwater systems: a near shore system, which extends from the ocean 18 km inland; and a sub-/proglacial system, which emanates from beneath Taylor Glacier into Lake Bonney and is associated with the discharge from Blood Falls. The brine networks in Taylor Valley challenge the notion that groundwater is negligible in regions of continuous permafrost, and signify the potential for a deep biosphere that is hydrologically and geochemically connected to the marine system and subglacial environments.
16013930 Englert, P. A. J. (University of Hawaii Manoa, Honolulu, HI); Bishop, J. L.; Patel, Shital; Gibson, Everett K. and Koeberl, Christian. Don Quixote pond sediments; surface and subsurface chemistry and mineralogy [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract P41A-3893, 5 ref., December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Don Quixote Pond, like Don Juan Pond in the South Fork of Wright Valley, Antarctica, is a model for calcium and chlorine weathering and distribution on Mars. It is located in the western part of the North Fork about 100 m above Mean Seawater Level; its brine is seasonally frozen . Field observations show zones of discoloration which grow lighter with distance from the pond edges. Four sediment cores, a set of radial surface samples, special surface samples, and samples of local rocks were obtained . We report on chemical and mineral analyses of traverse samples and on two cores. Core DQ20 is a northeastern shoreline core. Its soluble salt concentration exceeds 200 micromoles/g in the top 5 cm, and then falls to less than 70 micromoles/g at the permafrost depth of 15 cm. These concentrations are low when compared to similarly positioned locations at Don Juan Pond and to cores from Prospect Mesa close to Lake Vanda, Wright Valley. Halite, soda niter, tachyhydrite and/bischovite are suggested from the ionic molar relationships Measured halite concentrations of surface samples, collected along a traverse of 35 m from the pond outwards, range from over 5% to trace amounts, decreasing with distance. Gypsum is also present in almost all of these samples ranging from 0.2% to 2.6%, but does not exhibit a trend. However, in core DQ35, located at a distance of 15 m along the traverse, gypsum decreases from 2.5% to 0.6% from the surface to the permafrost depth of 12 cm. While DQ35 and radial samples show high quartz and albite abundance, samples that contained visible encrustations and evaporites are low in these minerals and rich in highly diverse alteration products. Don Juan Basin ponds may have formed by a complex surface water mobilization of weathering products  and local groundwater action [4,5]. In contrast, Don Quixote pond mineralogy and chemistry may be consistent with a less complex shallow and deep groundwater system origin .  Harris H.J.H. & Cartwright K., 1981, in: Dry Valley Drilling Project, L.D. McGinnis, ed., Antarctic Research Series, 33, 193-214.  Gibson E. K. et al., 1983, Journal of Geophysical Research, 88, A912-A928.  Dickson J. L. et al., 2013, Sci. Rep. 3: 1166.  Englert P. et al., GSA Annual Meeting 2013, abs. T65, 11-4.  Harris H.J.H., 1981, Ph.D. Dissertation, Univ. of Illinois.
16011848 Evans, Sarah G. (University of Colorado, Boulder, CO); Ge, Shemin; Zhou Min; Liang, S. and Chen Jianwei. Characterization of groundwater storage in the Heihe headwater watershed, Qinghai province, China [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract H51O-0824, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
A warming climate has led to decreases in permafrost extent and water insecurity in the Qinghai-Tibet Plateau in China. It is speculated that this will cause large-scale changes water resource availability. These speculations bring up questions: At what amount does groundwater storage contribute to stream flow in these headwater watersheds? How does groundwater storage change with increasing temperatures and decreasing permafrost extent? How will changes in permafrost and thus, groundwater storage, change seasonally? To address these questions, we have: (1) Developed a three-dimensional, groundwater flow and energy model for the Hulugou Watershed, the headwaters of the Heihe River located on the northern edge of the Qinghai-Tibet Plateau; (2) Analyzed seasonal base flow contribution to streamflow for the Hulugou Watershed using the two-parameter Kalinin method; and (3) Compared model results to geochemical data from the Hulugou Watershed. We derive a transient three-dimensional finite element coupled flow and energy transport model to characterize the groundwater and energy systems and quantify groundwater storage under long-term climatic conditions. The coupled hydrogeologic model incorporates the physics of water phase change, allowing for modeling of pore water freeze and thaw and permeability dependence on ice saturation. Major outcomes of the model include: spatial and temporal distributions of subsurface temperature, fluid pressure, groundwater storage, and discharge to the land surface. Model results highlight that groundwater recharges mainly at high elevations and discharges to springs and streams at low elevations. Results from base flow extraction of observed discharge data suggest that within the Hulugou Watershed, stream discharge is primarily from groundwater contributions in the form of base flow (53%). These results corroborate with geochemical data, highlighting temporal changes in groundwater storage.
16014129 Frassetto, Andrew (IRIS Consortium, Washington, DC); Busby, R. W.; Hafner, K.; Sauter, Allan and Woodward, R. Posthole sensor performance in the USArray transportable array; results from testing and initial deployments in Alaska and Canada [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract S12B-02, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
To prepare for the deployment of EarthScope's USArray Transportable Array (TA) in Alaska and adjacent Canada over the next several years, IRIS has evaluated different strategies for emplacing posthole seismometers. The goal of this work has been to maintain or enhance a TA station's noise performance while reducing the weight and logistical considerations required for its installation. Motivating this research are developments in posthole broadband seismometer design and the unique conditions for operating in this region, where many potential sites are located on frost-fractured outcrops or underlain by permafrost, in either case only accessible by helicopter. Current emplacement methods use a portable rig to auger or hammer-drill a hole 2.5-5 meters deep, in unconsolidated materials and permafrost, or by diamond bit coring 1-3 meters into rock. These emplacements are used at new TA installations and upgrades to existing AK network stations, and we compare their performance to the lower-48 TA vault installations. Through July 2014 there are eight TA and six upgraded AK stations operating under USArray; including five since at least October 2012, providing a detailed record of seasonal and/or site-specific behavior. We also discuss testing of different downhole configurations for 13 stations deployed at Pinon Flat Observatory in California since April 2014. Station performance is presented and compared using probability density functions summed from hourly power spectral density calculations. These are computed for the continuous time series of seismic data recorded on each seismic channel. Our results show that the noise performance of seismometers in Alaska with cased- or core- hole installations sometimes exceeds that of the quietest TA stations in the lower-48, particularly for the horizontal channels at long periods. We analyze and discuss the performance of example stations, comparing to other nearby seismometers. We also examine the performance of AK stations before and after they have been converted from surface vault to posthole configuration. At Pinon Flat, different methods for packing the seismometer and clamping its cables within cased holes has guided development of field procedure. The new posthole emplacements generally improve upon the mean performance of the lower-48 TA vaults.
16018161 Hafner, Katrin (IRIS Consortium, Washington, DC); Busby, R. W. and Enders, M. Status of EarthScope's transportable array in Alaska [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract S13C-4473, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
The EarthScope's Transportable Array has completed its first year of operations in Alaska. The proposed station grid uses 85 km spacing & consists of ~290 locations in Alaska and Western Canada. About 60 of the grid locations will be at existing seismic stations operated by the AEC, AVO & ATWC and are being upgraded with shallow borehole installations or higher quality sensors as appropriate. About 10 new stations will be collocated with PBO GPS stations. At the end of July 2014, 90% of the site reconnaissance has been completed, & 25 sites have been permitted with private landowners or the State of Alaska. 11 new TA stations have been installed, & 7 existing stations (AK network code) have been upgraded. Data from these stations is flowing to the Array Network Facility (ANF) and being archived at the IRIS DMC. As the Transportable Array has moved to Alaska, IRIS has experimented with different portable drills and drilling techniques to create shallow holes (1-5 m deep, 15-20 cm in diameter) in permafrost and rock outcrops for seismometer installation. The goal of these new methods is to maintain or enhance a station's noise performance while minimizing its footprint & the equipment, materials, and overall expense required for its construction. Motivating this approach are recent developments in posthole broadband seismometer design & the unique conditions for operating in Alaska, where most areas are only accessible by small plane or helicopter, & permafrost underlies much of the region. IRIS contracted with a drilling specialist to create a prototype Transportable Drill (less than 1300 lbs with tooling) that is capable of augering to 5 m in unconsolidated materials and permafrost, downhole hammering to 2.5 m in bedrock with a steel casing following the bit and diamond coring in solid rock to 2 m. This drill has been successfully deployed by helicopter to create a hole 2.7 m deep and 15 cm diameter in bedrock. The auger mode was used successfully to install a station in permafrost in Barrow, Alaska, & the hammer mode was used in unconsolidated materials at various locations in central and eastern Alaska. A second drill with more emphasis on downhole hammering will be developed in the Fall 2014. This would allow the same drill/tooling to be deployed and used in a variety of geologic conditions anticipated to be encountered at the reconned sites.
16011901 Kim, Y. (University of Montana, NTSG, Missoula, MT); Kimball, J. S.; Du, J. and Glassy, J. M. Improvements and extension to a global Earth system data record of daily landscape freeze-thaw status determined from satellite microwave remote sensing [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract IN31A-3706, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
A global satellite microwave Earth System Data Record of daily landscape freeze-thaw status (FT-ESDR) has been commonly used to quantify cold temperature impacts on productivity, phenology, evapotranspiration and the terrestrial carbon cycle. Overlapping 37 GHz, vertically polarized brightness temperature (Tb) measurements from the Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave Imager (SSM/I) were integrated to produce a temporally consistent and continuous global daily FT data record from 1979 to 2012 and derived at 25-km pixel resolution. In this study, we develop and evaluate FT-ESDR enhancements, including expanded record length and spatial coverage, alternate algorithm calibrations, and a finer scale FT classification. A larger global domain is evaluated that encompasses all land areas affected by seasonally frozen temperatures, including urban, snow-ice dominant, barren, and permafrost landscapes. The FT retrieval is obtained using a seasonal threshold algorithm (STA) that classifies daily Tb changes in relation to frozen and non-frozen Tb reference states on a per-pixel basis. STA sensitivity to FT reference states is evaluated and alternative ancillary data are applied for defining Tb reference conditions, including surface temperatures from global reanalysis and MODIS land surface temperature (LST) seasonal climatology. The resulting FT record shows mean annual spatial classification accuracies of 92 and 86 percent for PM and AM overpass retrievals relative to in-situ temperature measurements. Despite the larger domain and longer record, the new FT-ESDR showed a 1-3 percent spatial classification accuracy improvement over previous FT-ESDR versions. Areas with enhanced accuracy include the Central USA, Central Asia, and North and Central Europe. Sub-grid land surface spatial heterogeneity effects on the aggregate FT retrievals are also assessed to refine FT-ESDR data quality metrics. The results of this study are being applied for continuing FT-ESDR production and utility enhancements, and to inform development of similar FT algorithms and products from the NASA SMAP mission. This study was funded under the NASA MEaSUREs program.
16008765 Klene, Anna E. (University of Montana, Geography, Missoula, MT) and Nelson, F. E. Urban geocryology; mapping urban-rural contrasts in active-layer thickness, Barrow Penninsula, Northern Alaska [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS31A-3921, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
As development proceeds in the high latitudes, information about interactions between urban influences and the thickness of the active layer above permafrost becomes vital, particularly given the possibility of increasing temperatures accompanying climate change. Permafrost characteristics are often mapped at small geographical scales (i.e., over large areas), at low resolution, and without extensive field validation. Although maps of active-layer thickness (ALT) have been created for areas of relatively undisturbed terrain, this has rarely been done within urbanized areas, even though ALT is a critical factor in the design of roads, buildings, pipelines, and other elements of infrastructure. The need for detailed maps of ALT is emphasized in work on potential hazards in permafrost regions associated with global warming scenarios. Northern Alaska is a region considered to be at moderate to high risk for thaw-induced damage under climatic warming. The Native Village of Barrow (71°17'44"N; 156°45'59"W), the economic, transportation, and administrative hub of the North Slope Borough, is the northernmost community in the USA, and the largest native settlement in the circum-Arctic. A winter urban heat island in Barrow, earlier snowmelt in the village, and dust deposition downwind of gravel pads and roads are all urban effects that could increase ALT. A recent empirical study documented a 17 to 41 cm difference in ALT between locations in the village of Barrow and surrounding undeveloped tundra, even in similar land-cover classes. We mapped ALT in the Barrow Peninsula, with particular attention to contrasts between the urbanized village and relatively undisturbed tundra in the nearby Barrow Environmental Observatory. The modified Berggren solution, an advanced analytic solution to the general Stefan problem of calculating frost and thaw depth, was used in a geographic context to map ALT over the 150 km2 area investigated in the Barrow Urban Heat Island Study. The Berggren solution performed well for estimating mean values of ALT in rural and urban land-cover classes. Compared to the Stefan solution, it provides highly accurate results and is promising for use in urban environments as a vehicle for mapping fine-scale variations in ALT.
16008681 Kontar, Y. Y. (University of Alaska Fairbanks, Fairbanks, AK) and Eichelberger, J. C. Development of an online natural hazards course for the University of Arctic [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
In the past several decades, natural disasters killed several million people. The financial loses resulting from natural disasters often exceed $50 billion per year, and do not include social impacts such as mental anguish. However, disasters (i.e. earthquakes, floods, and cyclones) are merely natural processes--atmospheric disturbance and tectonic movement--that have always existed, and become dangerous to people and their property only in specific regions. The severity of natural disasters is commonly affected by human population density and land-use pattern. Since the human population continues to increase, there is a need to develop environmentally sound strategies to minimize annual fatality and property damage rates. With this need in mind, a group of (# here) geo- and social-scientists, graduate students, and professionals in disaster risk management and response gathered at the UActic Natural Hazards e-Course Development Workshop in Arkhangelsk Russia in March 2014. Participants came from Canada, Finland, Russia, and the United States. They developed an innovative strategy of communicating Arctic natural hazards to upper-undergraduate and beginning-graduate students with interests in science (both physical and social), emergency management, and policy related to natural disaster risk reduction. This eCourse is unique because it addresses disaster monitoring and response issues that are prevalent in the north, i.e. prolonged cold seasons, darkness, limited infrastructure, and long supply lines. Other outcomes for students include: a general knowledge of natural hazards and how they can be assessed, monitored, and disaster risk mitigated; and appreciation of how different Arctic countries view and manage hazards. The entire eCourse is interdisciplinary (an intersection of natural and social sciences and emergency management, multinational, and bilingual (English and Russian). It will consist of 10 modules (Intro/Basic principles, emergency mgmt., earthquakes, tsunamis, volcanoes, fire, floods, permafrost, downslope hazards, and social science) that will be easily adaptable by local instructors.
16008753 Liu Zhiping (Southwest Jiaotong University, Chengdu, China); Yuan, L. and Song, L. An experimental study to the seismoelectric responses of unfrozen water content [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS23B-3891, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
For many sections of the Qing-Cang railway line located in the permafrost regions, the monitoring of freeze-thaw cycling is a main mean for the railway operation as the seasons of the permafrost are the main factors that weaken the railway bed. The unfrozen water content is one of the most important parameters in the field monitoring and laboratory research of the freeze-thaw cycling of the permafrost. It has been already shown that the propagation of seismic waves inside a homogeneous porous medium induces a localized seismoelectric conversion field that moves along with the seismic waves, because of relative fluid motion in the pores. As the field is water saturation related, we initially conducted an experiment to study the seismoelectric responses varying with unfrozen water content. In the experiment, a cylinder frozen soil model which is heated gradually from bottom is set up to model a decrease temperature field, corresponding to that the unfrozen water content, from bottom to top. Then a seismic wave field is excited by a ultra acoustic transducer located on the top of the model and seismoelectric conversion responses are measured with a set of electrodes layout along the axis direction of the model with 1 cm depth inside the model. At the same time, the temperature at each electrode is measured by a heat sensitive resistance near the electrode. Keeping the heating from bottom of the model, the measurement is performed at a fixed time period until the temperature of each electrode is increasing over zero degree centigrade. The experiment observations show: 1) The travel velocity of the seismoelectric signals is decreasing with increasing of temperature, or that of unfrozen water content, which also verify the flexibility of the experiment. 2) The amplitudes of the seismoelectric signals generally increase with that of temperature, corresponding to that of unfrozen water content increasing. 3) As the seimoelectric responses are measured with point-like electrodes, the experiment related to unfrozen water content have a high resolution in space and time.
16008510 Rowland, J. C. (Los Alamos National Laboratory, Los Alamos, NM); Gangodagamage, C.; Shelef, E.; Pope, P. A.; Brumby, S. P. and Wilson, C. J. A morphology independent methodology for quantifying river planform change and characteristics from remotely sensed imagery [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract H52C-04, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
The ready availability of remotely sensed imagery offers the potential to examine river dynamics and planform characteristics at global scales. The Landsat archive currently offers the greatest spatial and temporal coverage of the entire globe. However, at 30 meter multispectral resolution detailed and accurate examination of planform changes using Landsat imagery is restricted to intermediate (» 500 m wide) to very large (» 1 km wide) rivers or smaller rivers with very high rates of change. Many of these larger river systems exhibit multi-threaded or braided channel patterns that present significant challenges for many of the existing methodologies for quantifying changes developed for single threaded meandering river systems. In order to examine planform changes in river systems across all scales and morphologies we developed a set of algorithms for quantifying river mobility and planform attributes using raster-based river masks extracted from remotely sensed data. Unlike many prior methodologies for measuring river migration and erosion that rely on changes in the position of river channel centerlines, our methods adopt river banks as a frame of reference for quantifying change. The choice of a bank-centric reference frame was motivated by both a primary interest in the spatial and temporal patterns of bank change and the significant challenge of extracting and comparing channel centerlines in multi-threaded systems. Unlike prior vector-based analysis of river channels, our analysis retains a raster-based representation of the river from the original imagery source. At each bank pixel, our algorithms compute linear rates of bank change, local channel width, bank curvature, and bank aspect (used for examination of the influence of thermal processes such as freeze thaw and permafrost influence). The spatially distributed measurements are also aggregated along equally spaced river segments to examine spatial patterns in erosion/accretion rates, and channel widths (both mean and effective in multi-threaded systems). Using our set of algorithms, we have successfully analyzed rivers varying in width from 10s of meters to greater than 1000 meters. Imagery sources have included aerial photography, high resolution satellite imagery, and coarser imagery such as SPOT, ASTER, and Landsat.
16011851 Rushlow, C. R. (Idaho State University, Idaho Falls, ID) and Godsey, S. Water storage capacity exceedance controls the timing and amount of runoff generated from Arctic hillslopes in Alaska, USA [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract H51O-0827, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Within the hydrologic community, there is a growing recognition that different runoff generation mechanisms can be unified within a "fill-and-spill" or storage exceedance paradigm. However, testing this unifying paradigm requires observing watersheds at a variety of scales under their full range of storage conditions, which are difficult to observe on typical human timescales in most environments. Polar watersheds underlain by continuous permafrost provide an opportunity to address these issues, because their total capacity for water storage follows a consistent annual cycle of expansion and contraction as a direct consequence of the extreme seasonality of solar energy availability. Cryotic conditions usually limit water storage to the surface snowpack and frozen soils, but summer warming allows the shallow subsurface to progressively thaw, providing a dynamic storage reservoir that is the convolved expression of several factors, including substrate hydrologic properties, watershed structure, and stochastic precipitation. We hypothesize that the amount of remaining water storage capacity in the system directly controls the amount and timing of runoff production for a given input. We test this prediction for six hillslope watersheds in Arctic Alaska over the 2013 and 2014 summer seasons from snowmelt in May through plant senescence in mid-August. We compare water table position to runoff produced from a given storm event or series of storm events. We find that no runoff is produced until a threshold water table position is exceeded; that is, as seasonal storage changes, runoff depends on watershed storage capacity exceedance. Preliminary results suggest that once that threshold is met, hydrologic response is proportional to storage exceedance. Thus, runoff production from Arctic hillslopes can be modeled from the surface energy balance and a reasonable estimate of shallow subsurface material properties. If storage exceedance is the key control on water export from Arctic watersheds, then the state of downstream aquatic ecosystems is strongly tied with upstream changes in surface energy balance and precipitation regimes. Future analyses will relate storage exceedance and water flux to biogeochemical cycling and solute fluxes in these hillslope watersheds.
16017691 Stillman, D. E. (Southwest Research Institute Boulder, Boulder, CO); Grimm, R. E. and McGinnis, R. N. Subsurface ice detection via low frequency surface electromagnetic method [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NS34A-03, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
The geophysical detection of ice in the cryosphere is typically conducted by measuring the absence of water. These interpretations can become non-unique in dry soils or in clay- and silt-rich soils that contain significant quantities of unfrozen water. Extensive laboratory measurements of electrical properties were made on permafrost samples as a function of frequency, temperature, and water content. These laboratory measurements show that the amount of ice can be uniquely obtained by measuring a frequency dependence of the electrical properties over a large frequency range (20 kHz - 10 Hz). In addition, the electrical properties of permafrost are temperature dependent, which can allow for an estimate of subsurface temperature. In order to test this approach in the field, we performed field surveys at four locations in Alaska. We used three low frequency electromagnetic methods: Spectral Induced Polarization (SIP: 20 kHz - 10 Hz), Capacively Coupled Resistivity (CCR: OhmMapper - 16.5 kHz), and DC Resistivity (Syscal ~ 8 Hz). At the Cold Regions Research and Engineering Laboratory permafrost tunnel near Fox, AK, we used SIP to measure the average ice concentration of 80 v% and determined the temperature to be -3±1°C by matching survey results to lab data. SIP data acquisition is very slow; therefore, at three sites near Tok, AK, we used CCR to perform reconnaissance of the area. Then SIP and DC resistivity were performed at anomalous areas. The three survey types give very similar absolute resistivity values. We found that while SIP gives the most quantitative results, the frequency dependence from the CCR and DC resistivity surveys is all that are needed to determine ice content in permafrost.
16008670 Stoffel, Markus (University of Geneva, Geneva, Switzerland); Trappmann, Daniel and Corona, Christophe. Enhanced rockfall activity from periglacial environments in the Swiss Alps correlates with warm summer temperatures over the course of the 20th century [abstr.]: in AGU 2014 fall meeting, American Geophysical Union Fall Meeting, 2014, Abstract NH43B-06, December 2014. Meeting: American Geophysical Union 2014 fall meeting, Dec. 15-19, 2014, San Francisco, CA.
Trees located on slopes underneath rock cliffs are excellent recorders of spatio-temporal rockfall activity and can provide long-term, yet annually resolved information on possible changes in rockfall frequency and/or magnitude. Rockfall in mountains depends, among others, on freeze-thaw cycles and/or the melting of winter ice in clefts. Its temporal frequency and magnitude is likely to be altered at higher elevations as a result of ongoing climatic changes, even more so in environments controlled by permafrost. Here we focus on >100 years of rockfalls released from periglacial environments in the Swiss Alps. Based on the 400 time series of century-old larch (Larix decidua Mill.) trees, we demonstrate that rockfall activity has increased significantly between the end of the Little Ice Age and today, and that enhanced rockfall activity is clearly correlated with above-average summer temperatures (and therefore melting permafrost). Rockfall is most abundant when after several years with above-average summer temperatures and its activity exhibits a certain lag in the response, presumably as a result of inertia in permafrost bodies. With ongoing climate change, rockfall activity is expected to increase, and thereby creating critical situations in several parts of the Alps where rockfalls without historical precedents will likely affect transportation corridors and/or inhabited areas. Research on the evolution of rockfall processes from periglacial environments can help to reduce the risk emanating from new processes or process magnitudes, and--in combination with scenario-based process modeling--facilitate the planning of adequate countermeasures.
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16016064 Ednie, M. (Geological Survey of Canada, Canada) and Smith, S. L. Permafrost temperature data 2008-2014 from community based monitoring sites in Nunavut: Open-File Report - Geological Survey of Canada, Rep. No. 7784, 18 p. 1 sheet, illus., 21 ref., 2015. Includes poster.
The Geological Survey of Canada collaborated with Nunavut communities and the territorial government to establish ten permafrost monitoring sites between 2008 and 2009. A summary of ground temperature data collected over a five year period is presented as a digital database. This information improves the characterization of permafrost thermal state and support climate change adaptation planning in Nunavut communities. Records of permafrost temperature indicate that mean annual temperatures at 15 m depth range from -5.06 °C in Pangnirtung to -11.93 °C in Resolute Bay. In the approximately 5 years since site establishment, ground temperatures at 15 m depth have increased between 0.04 °C/year and 0.25 °C/year with an average increase of 0.17 °C/year for all sites.
16016063 Oldenborger, G. A. (Geological Survey of Canada, Ottawa, ON, Canada); LeBlanc, A. M.; Stevens, C. W.; Chartrand, J. and Loranger, B. Geophysical surveys, permafrost conditions and infrastructure damage along the northern Yukon Alaska Highway: Open-File Report - Geological Survey of Canada, Rep. No. 7875, 61 p., illus. incl. sketch maps, 75 ref., 2015.
The Yukon Alaska Highway is a vital transportation route connecting the resource rich Yukon to southern Canada and serving as a commercial trade and tourist route between Canada and Alaska and between the lower US and Alaska. The construction and maintenance of transportation infrastructure in permafrost regions presents challenges and costs that do not exist in other areas due to sensitivity of the engineering properties of the substrate to changes in temperature. For the Yukon Alaska Highway, road surface and embankment damage can be associated with the prevalence of warm, ice-rich permafrost. Geophysical surveys can potentially provide valuable information on permafrost and ground-ice conditions. In cooperation with Yukon Highways and Public Works, three sections of the northern Yukon Alaska Highway (23 km) have been identified for testing the usefulness of geophysical surveys for understanding permafrost degradation and assisting with highway management. Results from capacitive resistivity and ground-penetrating radar surveys were analysed and interpreted along with surficial maps, records from geotechnical borehole investigations, and surface observations of highway distress such as roughness, longitudinal cracking, embankment failures and differential settlements. Several relationships are observed. 1) Linear settlements are the most frequent and severe type of observed damage often affecting both the road surface and the embankment. 2) High degrees of road roughness tend to occur over areas mapped as till, however, identified problem areas are largely associated with fluvial and glaciofluvial map units. 3) Observed damage often occurs with high degrees of highway roughness, but high degrees of roughness are not necessarily accompanied by observable damage. 4) There is no single consistent relationship between roughness or observed damage and borehole observations of ice-rich sediment or massive ice; observed damage appears to be associated with a variety of local ground ice conditions. 5) The geophysical results help elucidate the terrain conditions and support the conclusion that multiple subsurface processes contribute to highway degradation. Several geophysical signatures are interpreted as indicative of terrain conditions involving ice-rich ground, frozen ground, thaw-susceptible sediments and shallow groundwater. Interpretation of the geophysical results is considered most reliable when done in a local context and supported by additional data such as boreholes.
16016053 Duchesne, C. (Geological Survey of Canada, Ottawa, ON, Canada); Smith, S. L.; Ednie, M. and Chartrand, J. 20 years of active layer monitoring in the Mackenzie Valley, Northwest Territories: Scientific Presentation - Geological Survey of Canada, Rep. No. 31, 1 sheet, illus., 4 ref., 2015. Poster.
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