Abstract
Robust geomorphological interpretations of ice-marginal glacial, meltwater and palaeolake landforms are needed to constrain models of landform evolution that can be used to underpin high-resolution geochronologies of deglaciation. The Lago General Carrera/Bueno Aires (LGCBA) ice lobe of the former Patagonian Ice Sheet is one of the most researched in Patagonia, yet there remain contrasting landform evolution models partly because the spatiotemporal relationships between landforms in the LGCBA basin and tributary valleys have not been fully investigated. To this end we present a detailed, high-resolution glacial geomorphological map of the Los Antiguos sector of the LGCBA basin, and the tributary Río Jeinimeni valley, alongside sediment-landform assemblages from a broad suite of ice-marginal, subglacial, glaciolacustrine, glaciofluvial and paraglacial landforms. We introduce evidence for a previously unmapped ice-dammed lake within the Jeinimeni valley, which may have existed during the Last Glacial Maximum. Multiple isolated, ice-marginal proglacial lakes, which formed during the recession of the LGCBA ice lobe, were also mapped. The landform evidence is synthesised into a refined landscape evolution model for the LGCBA basin and Jeinimeni valley during the Last Glacial Interglacial Transition. The data presented demonstrate that previously reconstructed high LGCBA lake-level stands above 500 m asl were likely glaciolacustrine landforms created by ice-marginal lakes dammed by the LGCBA ice lobe. The mapping in the Jeinimeni valley highlights the potential for renewed dating investigations of landforms in tributary valleys to provide maximum limiting ages for the retreat of their associated glaciers. Furthermore, the identification of glaciolacustrine varved sediments associated with palaeolake Jeinimeni and the Los Antiguos sector of the LGCBA palaeolake, highlights the potential of these annually-resolved archives to infer spatiotemporal dynamics of main ice-lobe/tributary glaciers to improve palaeoenvironmental and palaeoclimatic reconstructions in the region.
Published Version
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