High-resolution sub-ice-shelf seafloor records of 20th-century ungrounding and retreat of Pine Island Glacier, West Antarctica
Journal of Geophysical Research: Earth Surface
American Geophysical Union
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Pine Island Glacier Ice-Shelf (PIGIS) has been thinning rapidly over recent decades, resulting in a progressive drawdown of the inland ice and an upstream migration of the grounding line. The resultant ice loss from Pine Island Glacier (PIG) and its neighboring ice streams presently contributes an estimated ∼10% to global sea-level rise, motivating efforts to constrain better the rate of future ice retreat. One route towards gaining a better understanding of the processes required to underpin physically-based projections is provided by examining assemblages of landforms and sediment exposed over recent decades by the ongoing ungrounding of PIG. Here we present high-resolution bathymetry and sub-bottom-profiler data acquired by autonomous underwater vehicle (AUV) surveys beneath PIGIS in 2009 and 2014 respectively. We identify landforms and sediments associated with grounded-ice flow, proglacial and subglacial sediment transport, overprinting of lightly-grounded ice-shelf keels and stepwise grounding-line retreat. The location of a submarine ridge (Jenkins Ridge) coincides with a transition from exposed crystalline bedrock to abundant sediment cover potentially linked to a thick sedimentary basin extending upstream of the modern grounding line. The capability of acquiring high-resolution data from AUV platforms enable observations of landforms and understanding of processes on a scale that is not possible in standard offshore geophysical surveys.
This work was supported by funding from the UK Natural En-vironment Research Coun ci l (NERC) iSTAR Pro gr a m m e Grants NE/J005665/2 andNE/J005770/1 and NERC Grant NE/G001367 /1 . DD was supported by NERC Trai n i n gGrant NE/K01 1 18 9/ 1 . FON wa s supported by NSF grant ANT-838735. MS was sup-ported by NERC Grant NE/J004766/1.
This is the author's accepted manuscript
Final version available from AGU via the DOI in this record
Accepted manuscript online: 11 August 2017