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.NSF ATM-0212450 Royal Society of London NERC Comer Science and Educational Fellowship Fondecyt 1070991 1050416 CEQUA Institute of Ecology and Biodiversity P02-051 PFB-23 L-DEO 7158 Weeks Postdoctoral Fellowshi

The Last Glacial Maximum and deglaciation in central Patagonia, 44°S–49°S

“…Mercer, 1968, 1976, 1982, 1983. Subsequent efforts to develop the glacial history of the PIS have used a wide range of geochronological techniques and are well summarised by several review papers on Quaternary (McCulloch et al, 2000;Rabassa and Clapperton, 1990;Rabassa and Coronato, 2009;Kaplan et al, 2008a;Glasser et al, 2004;Rodbell et al, 2009;Clapperton, 1993;Harrison and Glasser, 2011;Rabassa et al, 2000) and pre-Quaternary (Rabassa et al, 2011) glaciations.…”

Timing and nature of late Quaternary mountain glaciation

“…The mountain glacier chronologies for southern South America, around 458 S, are reviewed by Kaplan et al (2008). They show that glacial chronologies varied across the southern Andes.…”

Fluctuations of the Última Esperanza ice lobe (52°S), Chilean Patagonia, during the last glacial maximum and termination 1

“…A recent synthesis and analysis of the Late Quaternary glacial geochronology of Patagonia by Kaplan et al (2008a) concluded that glacial events during Marine Isotope Stage 2 (MIS2) were broadly in-phase with other areas around the globe. This analysis also revealed some differences in glacial histories along N-S and W-E transects at millennial timescales during T1, which could result from genuine spatial and temporal climate variability or geologic uncertainties (geomorphological, stratigraphic and dating methods).…”