A fault-bounded paleo-lake basin preserved beneath the Greenland Ice Sheet

Abstract:

Subglacial topography not only exerts strong controls on contemporary ice sheet dynamics, but also provides an important long-term record of landscape evolution pertaining to past glacial and non-glacial conditions. In particular, the diverse subglacial topography beneath the Greenland Ice Sheet bears the signatures of past processes of landscape evolution that record the development of the ice sheet since its inception. Here we present evidence from airborne radio-echo sounding, gravity and magnetic data for an enclosed paleo-lake basin situated beneath the ice sheet in northwest Greenland. Geomorphological analysis and hydrological modelling indicate that the basin once hosted a lake with a surface area of ~7,100 km² and a volume of ~580 km³. The basin and associated topography control the organisation of a preserved paleo-fluvial channel network, suggesting that the basin pre-dates widespread glaciation in northwest Greenland. We use flexural modelling to show that the morphology of the basin and surrounding topography is consistent with elastic plate flexure driven by mechanical displacement along a normal fault bounding the basin margin. Gravity and magnetic modelling indicate that the basin contains a sedimentary infill up to ~1.2 km thick. This material may contain valuable records of past ice sheet extent and environmental conditions in northwest Greenland. We therefore propose that the Camp Century Basin may be a promising target for future acquisition of ground-based active source seismic data and potential recovery of subglacial material by sub-ice drilling programs.