A new volcanic province: an inventory of subglacial volcanoes in West Antarctica

Maximillian Van Wyk De Vries,Andrew S Hein,Robert G Bingham

doi:10.1144/sp461.7

Maximillian Van Wyk De Vries, Andrew S Hein + Show 1 more

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https://doi.org/10.1144/sp461.7

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Abstract

Abstract The West Antarctic Ice Sheet overlies the West Antarctic Rift System about which, due to the comprehensive ice cover, we have only limited and sporadic knowledge of volcanic activity and its extent. Improving our understanding of subglacial volcanic activity across the province is important both for helping to constrain how volcanism and rifting may have influenced ice-sheet growth and decay over previous glacial cycles, and in light of concerns over whether enhanced geothermal heat fluxes and subglacial melting may contribute to instability of the West Antarctic Ice Sheet. Here, we use ice-sheet bed-elevation data to locate individual conical edifices protruding upwards into the ice across West Antarctica, and we propose that these edifices represent subglacial volcanoes. We used aeromagnetic, aerogravity, satellite imagery and databases of confirmed volcanoes to support this interpretation. The overall result presented here constitutes a first inventory of West Antarctica's subglacial volcanism. We identified 138 volcanoes, 91 of which have not previously been identified, and which are widely distributed throughout the deep basins of West Antarctica, but are especially concentrated and orientated along the >3000 km central axis of the West Antarctic Rift System.

Highlights

In other major rift systems of the world, rift interiors with thin, stretched crust are associated with considerable volcanism (e.g. Siebert & Simkin 2002)
We undertook our analysis on the Bedmap2 digital elevation model (DEM) (Fretwell et al 2013) domain encompassed by the West Antarctic Rift System (WARS), which incorporates all of West Antarctica, the Ross Ice Shelf and the Transantarctic Mountains fringing East Antarctica that flank the WARS (Elliott 2013)
LeMasurier et al 1990; Smellie & Edwards 2016), and it provides basic metrics concerning the locations and dimensions of the main volcanic zones. It serves to highlight the wide spread of subglacial volcanism beneath the West Antarctic Ice Sheet (WAIS), which may impact upon its response to external forcing through affecting coupling of the ice to its bed, and may have implications for future volcanic activity as ice cover thins

Summary

Introduction

In other major rift systems of the world, rift interiors with thin, stretched crust are associated with considerable volcanism (e.g. Siebert & Simkin 2002). In West Antarctica, where most knowledge of volcanoes is derived from subaerial outcrops in Marie Byrd Land, volcanoes are composed of intermediate alkaline lavas erupted onto a basaltic shield, with smaller instances being composed entirely of basalt and a few more evolved compositions (trachyte, rhyolite: LeMasurier et al 1990; LeMasurier 2013). We consider it likely that many structures in the WARS are basaltic. Cones present today are likely to be relatively young – we cannot use our method to distinguish whether or not the features are volcanically active

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