A 3He-based Holocene glacial chronology from Villarrica volcano, Chile

Understanding glacier changes during the Holocene provides key insights into climate variability and cryosphere dynamics. Villarrica volcano (39°S), situated within the Southern Volcanic Zone (SVZ) of Chile, preserves a well-defined record of past glacial extents, with moraines marking post-Last Glacial Maximum (LGM) glacial extents. Despite its potential, the glacial history of Villarrica and the SVZ still remains poorly constrained, limiting our understanding of glacier-climate interactions during the last deglaciation and Holocene.

We present new cosmogenic ³He surface exposure ages from 25 olivine-bearing moraine boulders to better constrain the glacial chronology at Villarrica during the late Holocene. Our chronology reveals multiple phases of moraine formation, including Neoglacial advances at 3350 ± 140 years (n=3) and 1740 ± 225 years (n=3), Little Ice Age (LIA; n=7) advances between 720 ± 340 and 370 ± 220 years, and the onset of modern retreat at 100 ± 50 years (n=12). These advances correlate with shifts in the Southern Westerly Winds (SWW), with Neoglacial advances driven by enhanced moisture delivery, while LIA advances reflect reduced ablation during cooler temperatures. Our findings also demonstrate extended ice positions during the industrial era until the early-to-mid 1900s which corresponds with regional evidence of delayed industrial era warming in Patagonia. Furthermore, the historical volcanic activity at volcanoes like Villarrica can significantly influence glacial landscapes and the preservation of moraines. This study provides a unique opportunity to reconstruct glacial behavior in a highly active volcanic region and offers valuable context for understanding the interactions between volcanic activity, climate, and glacial dynamics in the Southern Hemisphere throughout the Holocene.