Modern to glacial age subglacial meltwater drainage at Law Dome, coastal East Antarctica from topography, sediments and jokulhlaup observations

• Published in: Geological Society, London, Special Publications
• Main Authors: Goodwin, ID, Roberts, JL, Etheridge, DM, Hellstrom, J, Moy, AD, Ribo, M, Smith, AM
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geological Society Publishing House 2017
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Glaciology; East Antarctica; Law Dome; Antarc*; Antarctica; Ice Sheet
• Online Access: https://doi.org/10.1144/SP461.16; http://ecite.utas.edu.au/118721

Rare jkulhlaup events, also known as subglacial lake outburst flood events, have been observed at the Law Dome ice margin and provide an insight into the physical characteristics of subglacial meltwater and drainage. The subglacial topography based on data from the BEDMAP2 and ICECAP projects, together with subsurface transects of the ice margin obtained using groundpenetrating radar, reveal several lakes and lake-like depressions and the drainage pathways of two jkulhlaup events. Oxygen isotope typing of the meltwater during the most recent (2014) jkulhlaup event, combined with ice margin stratigraphy, enable the identification of ice tunnel melt pathways that exploit the 3090 dipping basal ice layering. The presence of subglacial meltwater beneath Law Dome during the Holocene to Glacial periods is confirmed by the dendritic drainage pattern in the subglacial morphology and extensive layers of basal regelation ice and subglacial carbonate precipitate deposits found within the Lken Moraines sediments. These subglacial carbonates, including ooid layers, formed from the mixing of glacial meltwater and seawater at 72 ka BP. The combined evidence indicates that the ocean discharge of subglacial meltwater may be variable and/or is periodically blocked by basal freezing events near the ice sheet terminus.