Evidence for late-glacial ice dammed lakes in the central Strait of Magellan and Bahia Inutil, southernmost South America

Abstract

This paper critically appraises the evidence for a succession of ice-dammed lakes in the central Strait of Magellan (c. 53°S) c. 17 000-12 250 cal. yr BP. The topographic configuration of islands and channels in the southern Strait of Magellan means that the presence of lakes provides compelling constraints on the position of former ice margins. Lake shorelines and glacio-lacustrine sediments have been dated by their association with a key tephra layer from Volcan Reclús (c. 15 510-14 350 cal. years bp) and by 14C-dated peats. The timing of glacial lake formation and associated glacier readvances is at odds with the rapid and widespread glacier retreat of the Patagonian ice fields further north after c. 17 000 cal. yr bp, suggesting rather that the lakes were coeval with the Antarctic Cold Reversal and persisted to the Late-glacial/Holocene transition. This apparent asymmetrical latitudinal response in glacier behaviour may reflect overlapping spheres of northern hemisphere and Antarctic climatic influence in the Magellan region.