Relative timing of last glacial maximum and late-glacial events in the central tropical Andes |
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| Authors: | Gordon RM Bromley Joerg M Schaefer Gisela Winckler Brenda L Hall Claire E Todd Kurt M Rademaker |
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| Institution: | 1. Department of Geosciences, Biogeology Eberhard Karls Universität Tübingen, Hölderlinstr. 12, D-72074 Tübingen, Germany;2. Senckenberg Centre for Human Evolution and Palaeoenvironment, Tübingen, Germany;3. Geoarchaeology Working Group, Institute for Archaeological Sciences, Eberhard Karls Universität Tübingen, Rumelinstr. 23, D-72072 Tübingen, Germany;4. University of Pennsylvania Museum, 3260 South Street, Philadelphia, PA 19104, USA;5. Accelerator Mass Spectrometry Laboratory, Department of Physics and School of Anthropology, University of Arizona, Tucson, AZ 85721, USA;6. Department of Prehistory and Quaternary Ecology, Eberhard Karls Universität Tübingen, Burgsteige 11, Tübingen, Germany;7. Department of Anthropology, Northern Illinois University, DeKalb, IL 60115, USA |
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| Abstract: | Whether or not tropical climate fluctuated in synchrony with global events during the Late Pleistocene is a key problem in climate research. However, the timing of past climate changes in the tropics remains controversial, with a number of recent studies reporting that tropical ice age climate is out of phase with global events. Here, we present geomorphic evidence and an in-situ cosmogenic 3He surface-exposure chronology from Nevado Coropuna, southern Peru, showing that glaciers underwent at least two significant advances during the Late Pleistocene prior to Holocene warming. Comparison of our glacial-geomorphic map at Nevado Coropuna to mid-latitude reconstructions yields a striking similarity between Last Glacial Maximum (LGM) and Late-Glacial sequences in tropical and temperate regions.Exposure ages constraining the maximum and end of the older advance at Nevado Coropuna range between 24.5 and 25.3 ka, and between 16.7 and 21.1 ka, respectively, depending on the cosmogenic production rate scaling model used. Similarly, the mean age of the younger event ranges from 10 to 13 ka. This implies that (1) the LGM and the onset of deglaciation in southern Peru occurred no earlier than at higher latitudes and (2) that a significant Late-Glacial event occurred, most likely prior to the Holocene, coherent with the glacial record from mid and high latitudes. The time elapsed between the end of the LGM and the Late-Glacial event at Nevado Coropuna is independent of scaling model and matches the period between the LGM termination and Late-Glacial reversal in classic mid-latitude records, suggesting that these events in both tropical and temperate regions were in phase. |
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