Abstract
AbstractThe landscape of Antarctica, hidden beneath kilometre‐thick ice in most places, has been shaped by the interactions between tectonic and erosional processes. The flow dynamics of the thick ice cover deepened pre‐formed topographic depressions by glacial erosion, but also preserved the subglacial landscapes in regions with moderate to slow ice flow. Mapping the spatial variability of these structures provides the basis for reconstruction of the evolution of subglacial morphology. This study focuses on the Jutulstraumen Glacier drainage system in Dronning Maud Land, East Antarctica. The Jutulstraumen Glacier reaches the ocean via the Jutulstraumen Graben, which is the only significant passage for draining the East Antarctic Ice Sheet through the western part of the Dronning Maud Land mountain chain. We acquired new bed topography data during an airborne radar campaign in the region upstream of the Jutulstraumen Graben to characterise the source area of the glacier. The new data show a deep relief to be generally under‐represented in available bed topography compilations. Our analysis of the bed topography, valley characteristics and bed roughness leads to the conclusion that much more of the alpine landscape that would have formed prior to the Antarctic Ice Sheet is preserved than previously anticipated. We identify an active and deeply eroded U‐shaped valley network next to largely preserved passive fluvial and glacial modified landscapes. Based on the landscape classification, we reconstruct the temporal sequence by which ice flow modified the topography since the beginning of the glaciation of Antarctica.
Highlights
The geomorphology of the subglacial landscape beneath the Antarctic Ice Sheet (AIS) is an essential part to our understanding of its future stability (Sugden & Jamieson, 2018)
This study focuses on the Jutulstraumen Glacier drainage system in Dronning Maud Land, East Antarctica
We regionally extend our interpretation of the structures we have classified in our study and define the following interpretation for landscape erosion and preservation: (1) a preserved fluvial landscape shaped by fluvial erosion, minimal glacial erosion and preserved thereafter; (2) a preserved glacial landscape, which was more strongly modified by selective linear erosion at some time in the past compared to (1); and (3) an active glacial landscape, in which the erosion has been long-lived and is still ongoing
Summary
The geomorphology of the subglacial landscape beneath the Antarctic Ice Sheet (AIS) is an essential part to our understanding of its future stability (Sugden & Jamieson, 2018). We use existing and new high-resolution airborne radar data to improve our understanding of the bed topography and landscape evolution in the source region of the Jutulstraumen Glacier (JG) in western Dronning Maud Land (DML; see Figure 1). Additional aerogeophysical datasets were acquired in the early 2000s in the Jutulstraumen region (Ferraccioli et al, 2005) and in western DML (Mieth & Jokat, 2014; Riedel et al, 2012) These data have supported detailed interpretations of the geological history of central and western DML, compilations of continental-scale bed topography and subglacial-lake distributions (Huybrechts et al, 2000; Fretwell et al, 2013; Goeller et al, 2016; Morlighem et al, 2020), and targeted studies of bathymetry beneath DML’s ice shelves (Eisermann et al, 2020; Smith et al, 2020). We only perform the water routing for the drainage basin of JG
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