Stability of Wilkes Subglacial Basin since before the Last Glacial Maximum signalled by englacial stratigraphy connecting Dome C and Talos Dome Ice Cores

Wilkes Subglacial Basin covers an area of 400,000 km², and stores a volume of ice equivalent to approximately 3 to 4 metres of sea-level rise. Both model simulations and observational evidence from offshore sediment cores indicate that the ice within the basin is susceptible to significant instability, and has seen extensive deglaciation and retreat in periods during the Pleistocene and Pliocene. Two ice cores are located proximal to the Wilkes Subglacial Basin: (i) EPICA Dome C ice core, situated at the ice divide in the upstream section of the catchment, with a record dating back to approximately 800 ka; and (ii) Talos Dome ice core, situated closer to the coast, and extending back to approximately 350 ka. Englacial stratigraphy imaged by radio-echo sounding can be dated at intersections with the ice cores, therefore extending the observational evidence of palaeo-behaviour of ice sheets beyond these isolated point-based measurements. To date, the englacial stratigraphy between these two ice cores has not been comprehensively investigated.

Here, we analyse the englacial stratigraphy using an airborne radio-echo sounding dataset comprising 61,000 km of along-track data, jointly acquired in 2005-2006 by the British Antarctic Survey (BAS) and the Italian Programma Nazionale di Ricerche in Antartide (the WISE-ISODYN survey). Data were acquired with the 150 MHz BAS Polarimetric Survey Instrument (PASIN). We have traced multiple englacial layers between Dome C and Talos Dome ice cores, with at least one layer of age 38 ka directly connecting the 1,100 km distance between the two ice cores. Our findings here provide robust geophysical confirmation that englacial layers across Antarctica correspond to chemically dated layers measured in deep ice cores more than 1,000 km apart. Overall, the architecture of englacial layers spanning between the two ice cores indicates a pervasive and stable ice geometry in the upper Wilkes Subglacial Basin during the last 60 ka. Future work will be directed towards extending the tracing of englacial stratigraphy towards the grounding line of Wilkes Subglacial Basin as calibration for ice-dynamic modelling to investigate the stability of the entire basin.