02 Nov 2023
 | 02 Nov 2023
Status: this preprint is open for discussion.

Extensive palaeo-surfaces beneath the Evans-Rutford region of the West Antarctic Ice Sheet control modern and past ice flow

Charlotte M. Carter, Michael J. Bentley, Stewart S. R. Jamieson, Guy J. G. Paxman, Tom A. Jordan, Julien A. Bodart, Neil Ross, and Felipe Napoleoni

Abstract. The subglacial landscape of Antarctica records and influences the behaviour of its overlying ice sheet. However, in many places, the evolution of the landscape and its control on ice sheet behaviour has not been investigated in detail. Using recently released radio-echo sounding data, we investigate the subglacial landscape of the Evans-Rutford region of West Antarctica. Following quantitative analysis of the landscape morphology under ice-loaded and unloaded conditions, we identify ten flat surfaces distributed across the region. Across these ten surfaces, we identify two distinct populations based on clustering of elevations, which potentially represent remnants of regionally coherent pre-glacial surfaces underlying the West Antarctic Ice Sheet (WAIS). The surfaces are bounded by deeply incised glacial troughs, some of which have potential tectonic controls. We assess two hypotheses for the evolution of the regional landscape: (1) passive margin evolution associated with the breakup of the Gondwana supercontinent, or (2) an extensive planation surface that may have been uplifted either in association with the West Antarctic Rift System or cessation of subduction at the base of the Antarctic Peninsula. We suggest that passive margin evolution is most likely of these two mechanisms, with the erosion of glacial troughs adjacent to, and incising, the flat surfaces likely having coincided with the growth of the WAIS. These flat surfaces also demonstrate similarities to other identified surfaces, indicating that a similar formational process may have been acting more widely around the Weddell Sea Embayment. The subsequent fluctuations of ice flow, basal thermal regime and erosion patterns of the WAIS are therefore controlled by the regional tectonic structures.

Charlotte M. Carter et al.

Status: open (until 11 Jan 2024)

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Charlotte M. Carter et al.

Charlotte M. Carter et al.


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Short summary
We use radio-echo sounding data to investigate the presence of flat surfaces beneath the Evans-Rutford region in West Antarctica. These surfaces may be what remains of laterally continuous surfaces, formed before the inception of the West Antarctic Ice Sheet, and we assess two hypotheses for their formation. Tectonic structures in the region may have also had a control on the growth of the ice sheet, by focusing ice flow into troughs adjoining these surfaces.