Renewed glacial activity during the Antarctic cold reversal and persistence of cold conditions until 11.5 ka in southwestern Patagonia

• Published in: Geology (Boulder) 2009-04, Vol.37 (4), p.375-378
• Main Authors: Moreno, P. I, Kaplan, M. R, François, J. P, Villa-Martínez, R, Moy, C. M, Stern, C. R, Kubik, P. W
• Format: Article
• Language: English
• Subjects: alkaline earth metals; Antarctic Polar Front; Argentina; Be-10; beryllium; Cenozoic; chronostratigraphy; Climate change; exposure age; geochronology; glacial environment; glacial features; glacial geology; glacial lakes; glaciation; Glaciers; Holocene; ice fields; ice movement; ice-marginal features; interglacial environment; isotopes; kames; lacustrine features; lakes; last glacial maximum; lower Holocene; metals; moraines; Paleoclimate science; paleoclimatology; Patagonia; Pleistocene; Quaternary; Quaternary geology; radioactive isotopes; South America; South Patagonian ice field; Southern Ocean; Studies; Temperature; Torres del Paine National Park; vegetation
• ISSN: 0091-7613; 1943-2682
• DOI: 10.1130/G25399A.1

Resolving the timing, direction, and magnitude of paleoclimate changes in the southern midlatitudes is a prerequisite for determining the mechanisms underlying abrupt and widespread climate changes between the hemispheres during the Last Glacial-Interglacial transition (LGIT). This issue is still debated, with previous studies producing apparently discordant findings. Here we show evidence for a glacial readvance and a cold episode between ca. 14.8 and 12.6 ka in southwestern Patagonia (50°S), contemporaneous with the Antarctic cold reversal. This was followed by ice recession under cold but relatively milder conditions until ca. 11.5 ka, when paleovegetation records indicate the onset of warm interglacial conditions. These findings differ from those reported in northern Patagonia (approximately 40°S), where deteriorating conditions before 13.5 ka were followed by the coldest part of the LGIT that lasted until ca. 11.5 ka. We interpret the apparent blend of Greenlandic and Antarctic cold phases as evidence for their co-occurrence in the southern middle latitudes in Patagonia, and hypothesize that the position of the Antarctic Polar Front modulated the strength of these cold events in regions to the north or south of it.