Abstract
ABSTRACT This study presents the first detailed glacial geomorphological map of the sediment-landform assemblages formed by three eastern outlet glaciers of the former Patagonian Ice Sheet. These glaciers occupied the Río Corcovado, Río Huemul and Lago Palena/General Vintter valleys, Chubut province, Argentina (43°S, 71°W). By combining remote sensing and field-mapping, we build on previous ice-sheet scale mapping and geological surveys to provide high-resolution spatial information on local ice-contact glaciogenic, glaciofluvial, glaciolacustrine, and subglacial landforms. Twenty-five landform types, many of which are newly mapped in the region, were digitized as georeferenced shapefiles over a 5300 km2 area. This map enables the identification of former ice-flow directions, relative ice-margin positions and glaciofluvial drainage pathways for each preserved Quaternary glaciation. It also elucidates the former areal extent, geolocation and spillways of glaciolacustrine bodies formed during the last deglaciation. The map delivers an essential framework on which to build robust glacier-scale geomorphological and geochronological reconstructions.
Highlights
The Patagonian region of southern South America was host to the most extensive Quaternary ice sheet of the southern hemisphere outside of Antarctica, the Patagonian Ice Sheet (PIS)
Hummocks and hummocky ridges Throughout the three valleys mapped in this study, we find an abundance of rounded to sub-rounded mounds of glaciogenic sediments, often termed hummocks in glacial geomorphology (Benn & Evans, 2014)
Our map illustrates the sediment-landform assemblages formed by the Quaternary fluctuations of three outlet glaciers in the northeastern sector of the former Patagonian Ice Sheet, the Río Corcovado, Río Huemul and Lago Palena/General Vintter outlet glaciers
Summary
The Patagonian region of southern South America was host to the most extensive Quaternary ice sheet of the southern hemisphere outside of Antarctica, the Patagonian Ice Sheet (PIS). García et al, 2019; Iglesias et al, 2016; Van Daele et al, 2016) there remains a general lack of published detailed mapping and geochronological data across the northeastern sector of the former ice sheet, between ∼39°S and ∼46.5°S (Darvill et al, 2015; Davies et al, 2020; Mendelová et al, 2017) Robust reconstructions from this region are needed to understand fully the PIS response to the Last Glacial Maximum (LGM) at these latitudes, and to investigate latitudinal dependencies on the timing of the local LGM throughout Patagonia (Darvill et al, 2015; Davies et al, 2020; García et al, 2018; 2019; Sagredo et al, 2011).
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