Talus flatirons on Seymour Island (Weddell Sea, Antarctica). Considerations about their genesis

Abstract

Talus flatirons are located to the NE of Seymour Island (Marambio, Antarctica) and show previous stages of slope evolution. Those morphologies imply a phase where slope accumulation dominated followed by the system overcoming a threshold that led to an incision period. It is estimated that this threshold was triggered by a glacioisostatic readjustment or/and by a climatic change. On the first one fluvial network gradient is rejuvenated, reactivating slope erosion. On the valley bottom tractive forces thresholds are overpassed, provoking incision. Climatic change hypothesis implies a warming where thawing of the active layer reacher greater depths, increasing runoff and bedload up to changing slope accumulation by downcutting.