On glaciation of the southern Andes with special reference to the Penı́nsula de Taitao and adjacent Andean cordillera (∼46°30′s)

Abstract

Ice fronts in the southern Andes during late Wisconsin–Weichselian glaciation reached maxima early and late in oxygen isotope stage 2. The first maximum occurred between 29,400 and 22,300 14C yr bp, and the second is centered around 15,000 14C yr bp. Glaciers at different latitudes varied in size, apparently in response to maximum levels of precipitation from the moisture-bearing southern Westerlies. Following deglaciation, which was reached in the interior midlatitude cordillera earlier than 12,300 14C yr bp, a late glacial readvance of Younger Dryas age is indicated by an increasing number of glacial geomorphic and paleoecological records, but it remains controversial. During stage 2, the cordillera supported a complex of ice caps and valley glaciers. On the Penı́nsula de Taitao and to the south, glaciers reaching low altitudes were evidently small compared with the large piedmont lobes that covered the sector encompassing the Región de los Lagos–Isla Grande de Chiloé to the north. Flowing from an icecap on Taitao, valley glaciers became coalesced only locally, thereby giving rise to small piedmont lobes. Adjacent to Taitao in the Andes, where there is little studied evidence of stage 2 glaciation, the oldest dated advances appear to be late Holocene. Glaciers at this latitude, situated in the Tres Montes fracture zone at the Antarctic–Nazca–South American triple plate junction, have been subjected to tectonic activity.