DOI: 10.1594/pangaea.838935
title: (Supplement 3) Radar sounding observations including bedrock and surface elevation and ice thickness in the ASB region, Antarctica

description: The first Cenozoic ice sheets initiated in Antarctica from the Gamburtsev Subglacial Mountains and other highlands as a result of rapid global cooling ~34 million years ago. In the subsequent 20 million years, at a time of declining atmospheric carbon dioxide concentrations and an evolving Antarctic circumpolar current, sedimentary sequence interpretation and numerical modelling suggest that cyclical periods of ice-sheet expansion to the continental margin, followed by retreat to the subglacial highlands, occurred up to thirty times. These fluctuations were paced by orbital changes and were a major influence on global sea levels. Ice-sheet models show that the nature of such oscillations is critically dependent on the pattern and extent of Antarctic topographic lowlands. Here we show that the basal topography of the Aurora Subglacial Basin of East Antarctica, at present overlain by 2-4.5 km of ice, is characterized by a series of well-defined topographic channels within a mountain block landscape. The identification of this fjord landscape, based on new data from ice-penetrating radar, provides an improved under¬standing of the topography of the Aurora Subglacial Basin and its surroundings, and reveals a complex surface sculpted by a succession of ice-sheet configurations substantially different from today's. At different stages during its fluctuations, the edge of the East Antarctic Ice Sheet lay pinned along the margins of the Aurora Subglacial Basin, the upland boundaries of which are currently above sea level and the deepest parts of which are more than 1 km below sea level. Although the timing of the channel incision remains uncertain, our results suggest that the fjord landscape was carved by at least two ice- flow regimes of different scales and directions, each of which would have over-deepened existing topographic depressions, reversing valley floor slopes.
description: The included data contains ice thickness data from the HiCARS ice sounding radar. The attached data was acquired from NERC funded ICECAP flights (radials lines flown from Casey Station) that were critical for this paper. The remaining ICECAP data was acquired on flights funded by NASA's Operation Ice Bridge; these data are available at the National Snow and Ice Data Center at http://www.nsidc.org/data/icebridge/. // Additional bed elevation data predating the ICECAP project can be accessed at http://www.ig.utexas.edu/research/projects/soar/SOAR_datanprojects.htm for the SOAR data, and http://www.antarctica.ac.uk//bas_research/data/access/bedmap/ from the BEDMAP project. Primary contributors to the BEDMAP data in this region were the NSF/SPRI/TUD airborne survey effort of the nineteen seventies and ground traverses by the Australian National Antarctic Research Expeditions in the nineteen eighties. Data extracted in the frame of a joint ICSTI/PANGAEA IPY effort, see http://doi.pangaea.de/10.1594/PANGAEA.150150
description: Supplement to: Young, Duncan A; Wright, Andrew P; Roberts, Jason L; Warner, Roland C; Young, Neal W; Greenbaum, Jamin S; Schroeder, Dustin M; Holt, John W; Sugden, David E; Blankenship, Donald D; van Ommen, Tas D; Siegert, Martin J (2011): A dynamic early East Antarctic Ice Sheet suggested by ice-covered fjord landscapes. Nature, 474(7349), 72-75