Bed conditions of Pine Island Glacier, West Antarctica

Alex Brisbourne, Andrew Smith, David Vaughan, Edward King, Damon Davies, Robert Bingham, Emma Smith, Isabel Nias, Sebastian Rosier

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)
3 Downloads (Pure)

Abstract

Although 90% of Antarctica's discharge occurs via its fast-flowing ice streams, our ability to project future ice-sheet response has been limited by poor observational constraints on the ice-bed conditions used in numerical models to determine basal slip. We have helped address this observational deficit by acquiring and analysing a series of seismic reflection profiles to determine basal conditions beneath the main trunk and tributaries of Pine Island Glacier (PIG), West Antarctica. Seismic profiles indicate large-scale sedimentary deposits. Combined with seismic reflection images, measured acoustic impedance values indicate relatively uniform bed conditions directly beneath the main trunk and tributaries, comprising a widespread reworked sediment layer with a dilated sediment lid of minimum thickness 1.5 ± 0.4 m. Beneath a slow-moving inter-tributary region, a discrete low-porosity sediment layer of 7 ± 3 m thickness is imaged. Despite considerable basal topography, seismic observations indicate that a till layer at the ice base is ubiquitous beneath PIG, which requires a highly mobile sediment body to maintain an abundant supply. These results are compatible with existing ice-sheet models used to invert for basal shear stress: existing basal conditions upstream will not inhibit further rapid retreat of PIG if the high-friction region currently restraining flow, directly upstream of the grounding line, is breached. However, small changes in the pressure regime at the bed, as a result of stress reorganisation following retreat, may result in a less-readily deformable bed and conditions which are less likely to maintain high ice-flow rates.
Original languageEnglish
Pages (from-to)419-433
Number of pages15
JournalJournal of Geophysical Research: Earth Surface
Volume122
Issue number1
Early online date22 Nov 2016
DOIs
Publication statusPublished - Jan 2017

Fingerprint Dive into the research topics of 'Bed conditions of Pine Island Glacier, West Antarctica'. Together they form a unique fingerprint.

Cite this