Glacial Geomorphology at Río Tranquilo Valley (47°S): Reconstruction of the Sequence of Glacial Events Since the Late-Glacial Through the Holocene

Abstract:

Reconstructing Patagonia glacial history constitutes a key element for understanding the underlying mechanisms of millennial climate change in the Southern Hemisphere. Here, we present the first detailed glacial geomorphic map of Río Tranquilo valley (47° S), which provide the basis for the reconstruction of the glacial and paleoclimatic history of the region. Río Tranquilo is a valley glacier located in the northern flank of Mount San Lorenzo, an isolated granitic massif, ~95 km to the east of the southern limit of the Northern Patagonian Icefield (NPI). Based on analysis of aerial photographs, satellite imagery and field-checking, we identified glacial landforms, including moraine, moraine ridges, outwash plain, proglacial lake and trimlines. We also included other non-glacial geomorphic features, such as deltas, rivers, lakes, alluvial fans, fluvial terraces, scarps and landslides. Preliminary 10Be ages suggest that all the glacial landforms identified here were deposited during the Late-Glacial and throughout the Holocene. Geomorphic evidence shows at least four periods of glacial stabilization. Identification of these multiples advances may hold implications for the design and interpretation of a dating programme. This study aims to extend the understanding of Patagonia glacial history since the Last Glacial period through the Holocene.