Ancient Tunnel Valleys: a snapshot into the past glacial dynamics

Subglacial and marine records from adjacent to continental ice sheets reflect climate changes, ice sheet dynamics, the intensity of erosion, and the effect of uplift and subsidence in onshore and offshore catchment areas. The glacial activity was responsible for major erosion and deepening of the shelf and the accumulation of eroded sediments along glaciated continental margins. In this study, We analyze and compare the spatial pattern and morphometry of a number of tunnel valleys and associated glacial landforms from over Antarctic margin. Detailed mapping of the tunnel valley morphology and the geometry of the infill based on high resolution of the bathymetric and seismic data indicates that subglacial meltwater was responsible for incising the valleys and depositing at least some of the infill. The characteristics of the valley morphology, orientations, and infill stratigraphy indicate the tunnel valleys were active over long periods of time and were formed by multiple drainage events and linked to the regional response of the Antarctic Ice Sheet. We further use a numerical model of bedrock erosion to quantify the major controls on the formation of the tunnel valleys, and elucidate how they interact with the subglacial hydrological system and paleo-ice sheet dynamics regionally.