Abstract

We combine sedimentological analysis, high-resolution imaging, and X-ray fluorescence data to investigate sedimentary processes and landscape evolution from lake records in central Isla Grande de Chilo & eacute; (42 degrees 23 ' S, 72 degrees 49 ' W), northwestern Patagonia between similar to 31-1.6 ka. The oldest section consists of laminated inorganic silts with a local geochemical signature deposited in a low-energy environment (Stage 1: similar to 31-26 ka), interrupted by hiatuses and coarse-grained allochthonous deposits associated with high-energy events (Stage 2: similar to 26-18 ka). The end of laminated facies and increasing organic matter led to a rising productivity trend and slope stability (Stages 3 and 4: similar to 18-14.1 ka, similar to 14.1-10.8 ka), along with volcaniclastic influx advected from the Andean Southern Volcanic Zone (Stage 5: similar to 10.8 -1.6 ka). We interpret sedimentation in proglacial lakes fed by varying intensities of glacier meltwater from the western margin of the Golfo Corcovado piedmont lobe during the LGM in Patagonia, followed by a sudden change to closed-basin lakes driven by glacier withdrawal at the onset of the Last Glacial Termination (similar to 18 ka). This detachment shifted the facies composition and arrangements toward predominance of climate and distal volcanic processes until similar to 1.6 ka. Our records capture salient millennial-scale features of the environmental evolution from western Patagonia since similar to 31 ka, and match paleoclimate records at zonal and hemispheric scales. Our facies analysis underscores the presence of centennial fluctuations and instantaneous processes through glacial and non-glacial lake regimes.