Glacial dynamics in southernmost South America during Marine Isotope Stage 5e to the Younger Dryas chron: a brief review with a focus on cosmogenic nuclide measurements

Abstract

The timing of major glacial changes between Marine Isotope Stage (MIS) 5e and the Younger Dryas chron (YD) in southern South America is reviewed. Focus is placed on studies that use cosmogenic nuclide measurements. However, other dated records and modelling results are also discussed to provide the broader glacial geological context. Limits on the state of glacial geologic knowledge are examined and suggestions are made as to how some of these can be addressed in future studies. Studies show that on the east side of the Andes at Lago Buenos Aires (45 degrees S) there is evidence indicating that following a MIS 6 glaciation ice was less extensive during MIS 4 than MIS 2. In contrast, on the west side of the Andes in the Chilean Lake District area, MIS 4 ice may have been more extensive than during MIS 2. Although Patagonia experienced an MIS 2 glaciation broadly in phase with that in other areas around the globe, there are differences in glacial histories between areas on millennial timescales. Climate reversals are evident in many records between ca. 17 and 10 ka. The timing of such Lateglacial activity, which included less extensive advances than during the local Last Glacial Maximum (LGM), varies somewhat between areas. This could be due to the relative influence of middle- to high-latitude climatic regimes. At present, chronological uncertainties prevent confident assignment of cosmogenic ages for glacial events at the millennial timescale and defining associated climate variability between different study areas.