Late glacial ice advances in the Strait of Magellan, southern Chile

Abstract

During the last glacial cycle low gradient glaciers repeatedly drained north-eastward into the Strait of Magellan and dammed extensive proglacial lakes in the central section of the strait.  This paper focuses on the two most recent glacial advances in the strait, culminating over 150 and 80 km from the present ice limits.  The timing of the first of the two advances has up to now, been ambiguous and depended on the interpretation of anomously older dates of 16,590-15.,800 yr BP for deglaciation at Puerto del Hambre.  Here, we show there is evidence from seismic data and truncated shorelines that the Puerto del Hambre basin has been tectonically displaced and that the dates do not represent minimums for deglaciation.  Several other dates show that the advance occurred sometime before 14,260 yr BP.  The timing of the second advance has been investigated using a refined tephrochronology for the region, which has also enabled a palaeoshoreline and glaciolacustrine sediments to be linked to a moraine limit.  14C dating of peat and a key tephra layer, above and below the glaciolacustrine deposits, respectively suggest that the advance culminated in the Strait of Magellan between 12,010 and 10,050 yr BP.