THE HOLOCENE GLACIER AND CLIMATE HISTORY OF CENTRAL PATAGONIA, A NEW RECORD FROM THE CALLUQUEO GLACIER

Major questions about the Holocene glacier history of the Southern Hemisphere remain unanswered, and as Earth's most recent geologic Epoch, it represents an important baseline for current glacier and climate change. Glacier chronologies from the Northern Hemisphere generally demonstrate that glaciers became more expansive during the Holocene, culminating in the Little Ice Age advances. Meanwhile, glaciers in New Zealand and southern Patagonia have followed the opposite trend, becoming progressively less extensive through the Holocene, suggesting that the climates of the two hemispheres may have been influenced by different drivers during this period. Given recent advances in the ¹⁰Be method, we are now in an excellent position to date precisely and directly the Holocene moraine sequence to the north in Patagonia. In this study we employ recent developments in the method, geomorphic studies, and historical data to reconstruct past Holocene glacier culminations in central Patagonia with unprecedented precision. We find that the Calluqueo glacier record fits the Southern Hemisphere model, with at least 9 glacier stabilization that we date from 6,790 ± 220 years ago to 145 ± 17 years ago. We also bracket the timing of two major periods of glacier retreat during this time, and compare our record with historical data to tie it into the most recent glacier history. This record represents one of the most precise, directly dated records of the Holocene glacier history in Patagonia, in particular in central Patagonia, and sheds light on the potential climate drivers.