Seafloor Depth of George VI Sound, Antarctic Peninsula, From Inversion of Aerogravity Data

Robin E Bell,Renata R Constantino,David F Porter,Tom A Jordan,Kirsty J Tinto

doi:10.1029/2020gl088654

Robin E Bell, Renata R Constantino + Show 3 more

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https://doi.org/10.1029/2020gl088654

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Abstract

AbstractGeorge VI Sound is an ~600 km‐long curvilinear channel on the west coast of the southern Antarctic Peninsula separating Alexander Island from Palmer Land. The Sound is a geologically complex region presently covered by the George VI Ice Shelf. Here we model the bathymetry using aerogravity data. Our model is constrained by water depths from seismic measurements. We present a crustal density model for the region, propose a relocation for a major fault in the Sound, and reveal a dense body, ~200 km long, flanking the Palmer Land side. The southern half of the Sound consists of two distinct basins ~1,100 m deep, separated by a −650 m‐deep ridge. This constricting ridge presents a potential barrier to ocean circulation beneath the ice shelf and may account for observed differences in temperature‐salinity (T‐S) profiles.

Highlights

The George VI Sound is a channel on the west coast of the southern Antarctic Peninsula separating Alexander Island from Palmer Land (Bell & King, 1998) (Figure 1)
The majority of the ice flow (96–97%) feeding the George VI Ice Shelf comes from glaciers on Western Palmer Land (Jenkins & Jacobs, 2008), which are currently experiencing the greatest mass loss from the Antarctic Peninsula (Gourmelen et al, 2019), contributing ~0.1 mm/a to global sea level rise in the last 2 decades (Schannwell et al, 2018)
The International Thwaites Glacier Collaboration (ITGC) line (Figure 1) was treated the same way as the tie line, and the inverted bathymetry was compared to the crossing profiles with a standard deviation (SD) of ~69 m

Summary

Introduction

The George VI Sound is a channel on the west coast of the southern Antarctic Peninsula separating Alexander Island from Palmer Land (Bell & King, 1998) (Figure 1). The majority of the ice flow (96–97%) feeding the George VI Ice Shelf comes from glaciers on Western Palmer Land (Jenkins & Jacobs, 2008), which are currently experiencing the greatest mass loss from the Antarctic Peninsula (Gourmelen et al, 2019), contributing ~0.1 mm/a to global sea level rise in the last 2 decades (Schannwell et al, 2018). Due to the presence of CDW, the water temperatures near the ice shelf base at both ice fronts exceed 1 °C (Jenkins & Jacobs, 2008). High basal melt rates around Antarctica have been interpreted as responses to variations in oceanic temperature and circulation (e.g., Holland et al, 2008; Jacobs et al, 2011). Future changes in basal melt depend on changes in ocean temperature as well as subsurface currents, steered by the cavity shape, highlighting the importance of accurate bathymetry data for future predictions (e.g., De Rydt et al, 2014; Dutrieux et al, 2014; Goldberg et al, 2019; Rosier et al, 2018)

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