Internal characteristics of ice-marginal sediments deduced from georadar profiling and sediment properties (Brøgger Peninsula, Svalbard)

Georadar and sedimentological data were acquired in the Ny-Ålesund area on Brøgger Peninsula in order to study diamicton in frontal areas of Vestre Brøggerbreen and Midre Lovénbreen. Parallel common offset georadar lines were acquired for information on thickness and layering and multioffset measurements served to deduce the subground velocity. Short permafrost cores (< 3 m depth) were extracted for ground verification. Several stratigraphic properties from the cored frozen sediments (i.e. grain size, ice content, total carbon content) allow characterizing the glacial detritus and sediment changes exciting electromagnetic reflections. Site dependent georadar data suggest that prominent reflections mainly coincide with sediment changes such as in ice content or major lithotype change. For example, at one site the contact to the underlying bedrock could be made visible and the moraine thickness could be inferred. In case of a discrete ice layer georadar trace modelling has helped to support interpretation of field measurements. Results of this study suggest that carbonaceous and clay-rich diamicton attenuates the electromagnetic wave propagation more than carbon-poor and clay-poor sediments.