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A Waterborne GPR Survey to Estimate Fine Sediments Volume and Find Optimum Core Location in a Rockglacier LakeNormal access

Authors: L. Sambuelli, N. Colombo, M. Giardino and D. Godone
Event name: Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics
Session: Integration of Geophysics III
Publication date: 06 September 2015
DOI: 10.3997/2214-4609.201413826
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 3.85Mb )
Price: € 20

Summary:
Rockglaciers are landforms related to ice-rich permafrost creep and represent a substantial reservoir of groundwater in the alpine region. Rockglacier lakes can occur when permafrost-ice meltwater released from rockglaciers, snowmelt, rain and groundwater find the geomorphologic conditions to be collected in an impermeable depression. This depression can be filled with fine-grained sediments (∅<1/16 mm) from at least three sources: 1) the dust contained in the snow covering the lake during winter, 2) the solid fraction of the runoff and meltwater from the rockglacier and 3) the runoff or the wind transport from the surrounding areas. Fine sediment volumes, bedding and typology offer large amount of information for interpreting the past and ongoing biological and abiotic processes in the catchment. In order to estimate the fine sediment volumes and plan a coring campaign in the Col d’Olen Rockglacier Lake (Aosta Valley, Italy) we performed waterborne GPR surveys with both 200 and 500 MHz antennas. After data processing we obtained the bathymetry of the top and the bottom of the fine sediments. Within the fine sediments unit we also found a discontinuity whose meaning will be investigated with a planned coring located in the zone with the maximum sediment thickness.


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