Evidence of early Holocene glacial advances in southern South America from cosmogenic surface-exposure dating
- 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706, USA
- 2Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706, USA, and School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, Scotland, UK
- 3Department of Earth and Planetary Science, Harvard University, Cambridge, Massachusetts 02138, USA
- 4Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706, USA
- 5PRIME Lab, Purdue University, West Lafayette, Indiana 47907, USA
Abstract
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).
Footnotes
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↵*Corresponding author: douglassgeology.wisc.edu
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↵GSA Data Repository item 2005041, Appendix DR1 (equilibrium-line altitude reconstructions, cosmogenic surface-exposure methods, and data reduction), Table DR1 (boulder compositions), Table DR2 (10Be data), Table DR3 (36Cl data), and Figure DR1 (valley topography and hypsometry), is available online at www.geosociety.org/pubs/ft2005.htm, or on request from editinggeosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301-9140, USA.
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- Accepted 28 October 2004.
- Received 30 August 2004.
- Revision received 26 October 2004.
- Geological Society of America
