Subaqueous evidence of the last glacial maximum and its termination in southern Patagonia

The glacial record of gLGM and T1 millennial-scale ice readvances is not continuous across the Patagonian Icefields. Whether missing records indicate that some ice lobes did not readvance during this time, or whether they are the result of burial or erosion of the record, remains to be investigated. We use high-resolution seismic reflection data to probe the glaciolacustrine sediments of Lago Argentino for subaqueous evidence of glacier readvances during the gLGM and T1. The data image a ∼150 m tall, >5.5 km wide double crested moraine and an overlying erosional landform preserved beneath >115 m of glaciolacustrine sediments, interpreted to mark the frontal positions of the ice during the gLGM and of subsequent grounding line oscillations during the early phase of T1. In addition, the data image the 5 km-wide, ∼120 m tall frontal, submerged counterpart of a moraine system previously mapped and dated on land associated with the ice readvance during the Antarctic Cold Reversal (ACR). By imaging submerged and buried glacial landforms on the eastern margin of the Southern Patagonian icefield, this study contributes first-order constraints on the extent of glacial conditions during the gLGM and T1 in Patagonia.