Articles | Volume 8, issue 2
Clim. Past, 8, 519–534, 2012

Special issue: Climate variations in South America over the last 2000 years

Clim. Past, 8, 519–534, 2012

Research article 15 Mar 2012

Research article | 15 Mar 2012

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 S. Bertrand et al.
  • 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, 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sedimentological and geochemical analysis of a 15 m long fjord sediment core from Golfo Elefantes, Chile, and historical documents from early Spanish explorers.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 into 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 suggest that the fluctuations of Gualas glacier during the last 5400 yr were mainly driven by changes in precipitation in the North Patagonian Andes.