How have past ice streams shaped the sea floor around Antarctica?

Introduction

Ice sheet reconstructions are of significant importance when researching interactions of ice sheets with the climate and ocean. By examining how ice sheets have responded to changes in the past, we are able to further understand how these ice sheets will react and change over future long-term timescales (Davies, 2018). An ice sheet can be defined as ‘a mass of glacial land extending more than 20,000 square miles’ (NSDIC, 2017), however the Antarctic ice sheet that we are studying extends over 5.4 million square miles (NSDIC, 2017). The Antarctic ice sheet is comprised of ice streams that are “a part of an inland ice sheet that flows rapidly through the surrounding ice” (Bentley, 1987). These ice streams are important to research as their behaviour and stability is essential to the overall dynamics of the Antarctica ice sheet and mass balance (Bennett, 2003). Once identified, ice streams can be used as an insight into past glacial behaviour and allow future prediction to be made of the response of contemporary ice sheets to future climate perturbations. (Stokes, 2001). Research has been undertaken to show that during the Last Glacial Maximum (LGM) the extent of the Antarctic ice sheet contributed 14m to the lowering of eustatic sea level (Denton, 2002). However, since the LGM, the Antarctica ice sheet has retreated, leaving a large range of geomorphological features uncovered. The aim of this report is to examine the submerged landscape surrounding the Antarctica and identify and examine the key geomorphological features formed by these ice streams and the dynamic processes that formed them. More specifically, this report will look at the Pine Island Trough (PIT) in the Amundsen Sea and the Ground-Zone Wedges (GZW) that were formed through the retreat of the Antarctica ice sheet.

Methods

Analysis in this report was mainly carried out through the use of ArcGIS. The multibeam echo-sounder dataset of the sea floor collected from the Antarctic continental shelf by the Swedish Icebreaker, RV Oden, in 2010 was used to construct topographic maps of the PIT floor. A hillshade raster for the bathymetric model was then created, made transparent and then placed over the PIT dataset. This allowed features on the sea floor terrain to be identified and examined such as the GZW. Through use of the 3D Analyst tool on ArcGIS, quantitative and qualitative data was produced examining the PIT area and the GZW within. This then allowed analysis to be undertaken on the subsequent results to help look at how ice streams formed the key features that were identified.

Results