Abstract. Few studies have examined in detail the sequence of events during the last glacial termination (T1) in the core sector of the Patagonian Ice Sheet (PIS), the largest ice mass in the southern hemisphere outside Antarctica. Here we report results from Lago Edita (47°8' S, 72°25' W, 570 m.a.s.l.), a small closed-basin lake located in a valley overridden by eastward-flowing Andean glaciers during the Last Glacial Maximum (LGM). Lago Edita shows glaciolacustrine sedimentation until 19,400 yr BP and a mosaic of cold-resistant, hygrophilous conifers and rainforest trees, along with alpine herbs between 11,000-19,400 yr BP. Increases in arboreal pollen at 13,200 and 11,000 yr BP led to the establishment of forests near Lago Edita between 9000–10,000 yr BP. Our data suggest that the PIS retreated at least ~90 km from its LGM limit between ~19,400–21,000 yr BP and that scattered, low-density populations of cold-resistant hygrophilous conifers, rainforest trees, high Andean and steppe herbs thrived east of the Andes during the LGM and T1, implying high precipitation and SWW intensity at 47° S. We interpret large-magnitude increases in arboreal vegetation as treeline-rise episodes driven by warming pulses at 13,200 and 11,000 yr BP coupled with a decline in SWW influence at ~11,000 yr BP, judging from the disappearance of cold-resistant hygrophilous trees and herbs. We propose that the PIS imposed a regional cooling signal along its eastern, downwind margin through T1 that lasted until the separation of the North and South Patagonian icefields along the Andes. We posit that the withdrawal of glacial and associated glaciolacustrine environments through T1 provided a route for the dispersal of hygrophilous trees and herbs from the eastern flank of the central Patagonian Andes, contributing to the afforestation of the western Andean slopes and pacific coasts of central Patagonia during T1.
The last glacial termination on the eastern flank of the central Patagonian Andes (47 ° S)
