Englacial and subglacial conditions in a deep-interior ice stream tributary, East Antarctica

• Main Authors: Bingham, RG, Siegert, MJ
• Format: Other Non-Article Part of Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: Antarctic; East Antarctica; East Antarctic Ice Sheet; South Pole; Filchner Ice Shelf; Support Force Glacier; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Scott Polar Research Institute; South pole
• Online Access: http://hdl.handle.net/1983/012dcbaf-2415-4251-b49a-6ae957779eb9; https://research-information.bris.ac.uk/en/publications/012dcbaf-2415-4251-b49a-6ae957779eb9

The identification and delineation of ice streams and their tributaries is critical to evaluating the form and flow of the major ice sheets and their long-term stability. However, particularly within the East Antarctic Ice Sheet (EAIS), where recent research has demonstrated that ice streams and their tributaries may originate several hundreds of kilometres inland, our delineation of ice stream coverage is far from complete, potentially compromising our ability to provide good estimates of present-day and future changes in ice sheet mass balance. Interferometric synthetic aperture radar (InSAR) imagery implies that ice flowing through the Support Force Glacier (82º45’S, 046º30W) to the Filchner Ice Shelf is derived largely from a fast-flow feature originating from at least 500 km inland (the southerly limit of InSAR), suggesting that this “Support Force Ice Stream� (SFIS) may be highly significant for the drainage and mass balance of the EAIS. We analyse englacial and subglacial conditions within and around the margins of the SFIS using RES imagery collected from 1974-1979 by a consortium of the UK Scott Polar Research Institute, US National Science Foundation and Technical University of Denmark. The original analogue records have been scanned and incorporated both into a conventional GIS (ArcView) and an advanced three-dimensional visualisation scheme (Fledermaus), providing powerful new tools for quantitative analysis. Where clear internal layers are visible within the RES profiles, we distinguish between “well-preserved� layering which parallels the bed topography and implies slow flow, and “buckled� layering which diverges from bed topography and reflects fast flow/ice streaming. We also use signal scattering to identify areas of crevassing and marginal shear, and investigate the occurrence of possible fault features within the basal layers of some RES profiles. This novel application of RES data collected 26-31 years ago has enabled for the first time the delineation of the SFIS as far inland as the South Pole, and confirms that fast flow takes place deep within the interior of the EAIS. The identification and delineation of ice streams and their tributaries is critical to evaluating the form and flow of the major ice sheets and their long-term stability. However, particularly within the East Antarctic Ice Sheet (EAIS), where recent research has demonstrated that ice streams and their tributaries may originate several hundreds of kilometres inland, our delineation of ice stream coverage is far from complete, potentially compromising our ability to provide good estimates of present-day and future changes in ice sheet mass balance. Interferometric synthetic aperture radar (InSAR) imagery implies that ice flowing through the Support Force Glacier (82º45’S, 046º30W) to the Filchner Ice Shelf is derived largely from a fast-flow feature originating from at least 500 km inland (the southerly limit of InSAR), suggesting that this “Support Force Ice Stream� (SFIS) may be highly significant for the drainage and mass balance of the EAIS. We analyse englacial and subglacial conditions within and around the margins of the SFIS using RES imagery collected from 1974-1979 by a consortium of the UK Scott Polar Research Institute, US National Science Foundation and Technical University of Denmark. The original analogue records have been scanned and incorporated both into a conventional GIS (ArcView) and an advanced three-dimensional visualisation scheme (Fledermaus), providing powerful new tools for quantitative analysis. Where clear internal layers are visible within the RES profiles, we distinguish between “well-preserved� layering which parallels the bed topography and implies slow flow, and “buckled� layering which diverges from bed topography and reflects fast flow/ice streaming. We also use signal scattering to identify areas of crevassing and marginal shear, and investigate the occurrence of possible fault features within the basal layers of some RES profiles. This novel application of RES data collected 26-31 years ago has enabled for the first time the delineation of the SFIS as far inland as the South Pole, and confirms that fast flow takes place deep within the interior of the EAIS.