Clim. Past Discuss., 7, 2937-2980, 2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP.
Precipitation as the main driver of Neoglacial fluctuations of Gualas glacier, Northern Patagonian Icefield
S. Bertrand1,2,3, K. A. Hughen1, F. Lamy2, J.-B. W. Stuut4,5, F. Torrejón6,7, and C. B. Lange8
1Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
2Alfred Wegener Institute, Bremerhaven, Germany
3Renard Centre of Marine Geology, University of Ghent, Krijgslaan, 281 s.8, 9000 Gent, Belgium
4MARUM, Center for Marine Environmental Sciences, University of Bremen, Germany
5NIOZ Royal Netherlands Institute for Sea Research, Texel, The Netherlands
6EULA Center, University of Concepción, Chile
7Patagonian Ecosystems Research Center (CIEP), Coyhaique, Chile
8Department of Oceanography and COPAS Center, University of Concepción, Chile

Abstract. Glaciers are frequently used as indicators of climate change. However, the link between past glacier fluctuations and climate variability is still highly debated. Here, we investigate the mid- to late-Holocene fluctuations of Gualas Glacier, one of the northernmost outlet glaciers of the Northern Patagonian Icefield, using a multi-proxy sedimentological and geochemical analysis of a 15 m long fjord sediment core from Golfo Elefantes, Chile, and historical documents from early Spanish explorers. Our results show that the core can be sub-divided in three main lithological units that were deposited under very different hydrodynamic conditions. Between 5400 and 4180 cal yr BP and after 750 cal yr BP, sedimentation in Golfo Elefantes was characterized by the rapid deposition of fine silt, most likely transported by fluvio-glacial processes. By contrast, the sediment deposited between 4130 and 850 cal yr BP is composed of poorly sorted sand that is free of shells. This interval is particularly marked by high magnetic susceptibility values and Zr concentrations, and likely reflects a major advance of Gualas glacier towards Golfo Elefantes during the Neoglaciation. Several thin silt layers observed in the upper part of the core are interpreted as secondary fluctuations of Gualas glacier during the Little Ice Age, in agreement with historical and dendrochronological data. Our interpretation of the Golfo Elefantes glaciomarine sediment record in terms of fluctuations of Gualas glacier is in excellent agreement with the glacier chronology proposed for the Southern Patagonian Icefield, which is based on terrestrial (moraine) deposits. By comparing our results with independent proxy records of precipitation and sea surface temperature, we demonstrate that the fluctuations of Gualas glacier during the last 5400 yr were mainly driven by changes in precipitation in the Andes.

Citation: Bertrand, S., Hughen, K. A., Lamy, F., Stuut, J.-B. W., Torrejón, F., and Lange, C. B.: Precipitation as the main driver of Neoglacial fluctuations of Gualas glacier, Northern Patagonian Icefield, Clim. Past Discuss., 7, 2937-2980, doi:10.5194/cpd-7-2937-2011, 2011.
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