Abstract
Abstract. Unanswered questions about the glacier and climate history preceding the global Last Glacial Maximum (LGM) in the southern temperate latitudes remain. The Marine Isotope Stage (MIS) 3 is normally understood as a global interstadial period; nonetheless its climate was punctuated by conspicuous variability, and its signature has not been resolved beyond the polar realms. In this paper, we compile a 10Be depth profile, single grain infrared (IR) stimulated luminescence dating and 14C samples to derive a new glacier record for the principal outwash plain complex, deposited by the western Patagonian Ice Sheet (PIS) during the last glacial period (Llanquihue Glaciation) on the Isla de Chiloé, southern Chile (42∘ S). In this region, the Golfo de Corcovado Ice Lobe left a distinct geomorphic and stratigraphic imprint, suitable for reconstructing former ice dynamics and timing of past climate change. Our data indicate that maximum glaciation occurred by 57.8±4.7 ka without reaching the Pacific Ocean coast. Ice readavanced and buttressed against the eastern side of the Cordillera de la Costa again by 26.0±2.9 ka. Our data further support the notion of a large ice extent during parts of the MIS 3 in Patagonia and New Zealand but appear to contradict near contemporaneous interstadial evidence in the southern midlatitudes, including Chiloé. We propose that the PIS expanded to its full-glacial Llanquihue moraines, recording a rapid response of southern mountain glaciers to the millennial-scale climate stadials that punctuated the MIS 3 at the poles and elsewhere.
Highlights
We lack thorough knowledge on the timing of the local Last Glacial Maximum for the Southern Hemisphere mountain glaciers because the dating of their terminal moraines and associated outwash plains has remained spatially variable
The Marine Isotope Stage (MIS) 3 is normally referred to as a global interstadial period when southern conifer forest expanded to ice-free low-land areas, but glaciers are known to have advanced in southern Chile and New Zealand by this time (Villagrán et al, 2004; Kelley et al, 2014; Darvill et al, 2015; García et al, 2018)
Despite the fact that paleoclimate records are well-resolved in the polar regions, main knowledge gaps remain for the terrestrial southern midlatitudes before the global Last Glacial Maximum (LGM) time frame
Summary
We lack thorough knowledge on the timing of the local Last Glacial Maximum (lLGM) for the Southern Hemisphere mountain glaciers because the dating of their terminal moraines and associated outwash plains has remained spatially variable. In addition to MIS 2, new records indicate extensive glaciers during MIS 3, MIS 4 and late MIS 5 in southern Patagonia and New Zealand, but uncertainty remains as to whether this is a common feature of southern midlatitude glacial history (Schaefer et al, 2015; Williams et al, 2015; Darvill et al, 2015; Kelley et al, 2014; García et al, 2018; Davies et al, 2020; Mendelová et al, 2020; Shulmeister et al, 2010). The MIS 3 is normally referred to as a global interstadial period when southern conifer forest expanded to ice-free low-land areas, but glaciers are known to have advanced in southern Chile and New Zealand by this time (Villagrán et al, 2004; Kelley et al, 2014; Darvill et al, 2015; García et al, 2018). Despite the fact that paleoclimate records are well-resolved in the polar regions, main knowledge gaps remain for the terrestrial southern midlatitudes before the global LGM time frame
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