Late glacial sub glacial lake sediments recovered and sampled in Pine Island Bay, Antarctica

• Main Authors: Kuhn, Gerhard, Hillenbrand, Claus-Dieter, Kasten, Sabine, Smith, James A., Nitsche, Frank O., Klages, Johann Philipp
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Antarctic; The Antarctic; West Antarctic Ice Sheet; Glacial Lake; Island Bay; Pine Island Bay; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Pine Island
• Online Access: https://epic.awi.de/id/eprint/39057/; http://isaes2015goa.in/docs/XII%20ISAES%202015%20Abstract%20Volume.pdf; https://hdl.handle.net/10013/epic.46343

Subglacial meltwater facilitates rapid ice flow beneath concurrent ice sheets, and there is widespread evidence for a dynamic subglacial water system beneath the Antarctic Ice Sheet. It steers and affects the pattern of ice flow and is a direct result from boundary processes acting at the base of the ice sheet, i.e. pressure induced basal melting. Consequently, the occurrence of subglacial meltwater plays an important role in bedrock erosion, subsequent resedimentation, and in shaping the topography of icesheet beds. Here we present new geological and geochemical data from sediments recovered on the West Antarctic continental shelf in Pine Island Bay that we interpret as reliable indicators for deposition in a palaeosubglacial lake beneath the formerly expanded West Antarctic Ice Sheet, presumably during or following the Last Glacial Maximum. Characteristic changes of sedimentary facies and geochemical profiles within these cores taken on RV Polarstern expeditions ANTXXIII/ 4 (2006) and ANTXXVI/ 3 (2010) support the presence of an active subglacial lake system during the late stages of the last glacial period. These findings have important implications for palaeo icesheet dynamics, suggesting there was considerable water available to lubricate the bedrockice interface and deposit water saturated subglacial sediments (soft tills). Based on our investigations performed so far, we suggest that the transition from subglacial lake to contact with the ocean took place in the early Holocene. During this time, we speculate, that the ice sheet thinned and successively transformed into an ice shelf with subice cavities flushed by tidal currents. Based on bathymetric maps and relative sea level curves we will aim to estimate ice thickness as the grounding line retreated across the subglacial lake threshold further inland. Our findings may also have implications for ice sheet models, which have to consider the predominantly nonlinear effects related to subglacial hydrology.