Evidence of early Holocene glacial advances in southern South America from cosmogenic surface-exposure dating

摘要

Cosmogenic nuclide surface-exposure dating reveals that glaciers in southern South America (46°S) advanced ca. 8.5 and 6.2 ka, likely as a result of a northward migration of the Southern Westerlies that caused an increase in precipitation and/or a decrease in temperature at this latitude. The older advance precedes the currently accepted initiation of Holocene glacial activity in southern South America by 3000 yr. Both of these advances are temporally synchronous with Holocene climate oscillations that occurred in Greenland and the rest of the world. If there are causal links between these events, then rapid climate changes appear to be either externally forced (e.g., solar variability) or are rapidly propagated around the globe (e.g., atmospheric processes).