Late glacial paleoclimate of the central Altiplano constrained by cosmogenic ^3He dating and 'clumped-isotope' paleothermometry

Abstract

The timing and causes of the last deglaciation in the tropical Andes are still poorly constrained. Moreover, the paleoclimatic conditions that existed in this region during the paleolake Tauca highstand between 17 and 15 ka [1, 2] are still uncertain. Here we present new cosmogenic ^3He ages from glacial landforms of Cerro Tunupa (20°S) showing that, in the central part of the Altiplano, glaciers persisted at their maximum position between 17 and 15 ka, and retreated synchronously with the drop of the paleolake Tauca highstand after 15 ka. This result is different from previous moraine dating [3] that indicates an earlier (~34 ka) local glacial maximum in the northern part of Altiplano. This discrepancy most likely reflects spatial variability of past precipitation. Indeed, the extent of mountain glaciers is determined both by temperatures and local precipitation.