Reconstruction of glacial history of the area north of Svalbard/Spitsbergen

• Main Author: Adhikari, Dilip
• Format: Thesis
• Language: unknown
• Published: HafenCity University Hamburg 2016
• Subjects: Arctic Ocean; Barents Sea; Fram Strait; Ice Shelf; Iceberg*; Sea ice; Svalbard; Svalbard margin; Yermak plateau; Spitsbergen
• Online Access: https://epic.awi.de/id/eprint/42676/; https://hdl.handle.net/10013/epic.49265

Vast areas of the Yermak Plateau have been affected by major glaciations during the Quaternary. Our understanding of the timing and dimensions of the marine-based ice sheets in the Svalbard-Barents Sea region during the Quaternary today is still limited. The main objective of this thesis is to improve the knowledge in the glacial history on the aspect of when and how the Arctic Ocean with the Svalbard-Barents Sea Ice Sheets has been reconnected. Multibeam swath bathymetry, high-resolution subbottom acoustic profiling and sediment coring can be combined to identify ice-grounding events in the past. A case study is presented here for the Yermak Plateau and northern Svalbard margin located between 79° and 83°N and 2° and 16°E. The geophysical datasets were acquired from research vessels, Polarstern (PS) and Maria S. Merian (MSM), during the expeditions PS92 and MSM31. Three types of subglacial features were detected from bathymetric mapping, in the form of ice- produced mega-scale glacial lineations, iceberg plowmarks of various dimensions and a grounding-zone wedge. The acoustic stratigraphy showed four acoustic facies: the first with undulating laminated upper surface and very little acoustic penetration below, indicative of highly disturbed sediments by ice action; a second with a thick laminated strata over acoustically transparent lenses, resulting from debris flow; a third with well-developed stratification produced by sedimentation under calm condition, often laminated with parallel to sub-parallel internal reflectors; and the last with well-stratified strata also produced by sedimentation under calm environment but present over a strong and undulating reflector at the base. Mega-scale lineations are attributed to be formed during the Saalian with the grounding of large ice shelf fragments exiting towards the Fram Strait. Quasi-linear huge plowmarks are likely to be formed either by multiple keels of a single megaberg or by keels of several icebergs that are trapped together within multi-year sea ice ...