Journal Article

PreJuSER-11662

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Reconstructing 2000 years of hydrological variation derived from laminated proglacial sediments of Lago del Desierto at the eastern margin of the South Patagonian Icefield, Argentina

Kastner, S. ; Enters, D. ; Ohlendorf, C. ; Haberzettl, T. ; Kuhn, G. ; Lücke, A.FZJ* ; Mayr, C. ; Reyss, J.-L. ; Wastegard, S. ; Zolitschka, B.

2010
Elsevier Science Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.gloplacha.2010.04.007

Abstract: Lago del Desierto (49 degrees 02'S, 72 degrees 51'W) is situated in the climatically sensitive area of Southern Patagonia close to the Hielo Patagonico Sur (HPS or South Patagonian Ice Field, Argentina). Next to marine records and Antarctic ice cores, this continental area is important to reveal hemispheric and global climate trends. As instrumental climate records from this region are generally short and scarce, environmental archives are the only source of long-term records of climate variations. In this study, the potential of laminated proglacial sediments from Lago del Desierto as a palaeoclimate archive is evaluated. Two parallel gravity cores (max. length 283 cm) were analysed using a multi-proxy approach. Radiometric dating (C-14, Pb-210 and Cs-137) and tephrochronology document that the sediment cover the last 2000 years. Especially in the middle part of the record, numerous turbidites make climate variations difficult to decipher. However, after exclusion of event layers changes in sedimentological, mineralogical, and geochemical parameters reveal a long-term trend of runoff variations and sediment accessibility controlled by changes in temperature and precipitation. An abrupt transition in sediment composition occurred around AD 850 and is interpreted as a change in sediment availability related to the initial exposure of formerly glaciated areas in the catchment. This striking change mirrors the onset of warmer climate conditions during the Medieval Climate Anomaly. Moreover, the Little Ice Age cooling and the subsequent 20th century warming can be traced in the sediment record corresponding to an overall trend observed for southern South America. The proglacial lacustrine sediment record of Lago del Desierto thus constitutes a link between glacier studies of the HPS and other terrestrial climate archives in a region were long, and continuous climate records are still rare. (C) 2010 Elsevier B.V. All rights reserved.

Keyword(s): J ; proglacial lake (auto) ; laminated sediments (auto) ; palaeoclimatology (auto) ; Pb-210/Cs-137-dating (auto) ; Medieval Climate Anomaly (auto) ; Little Ice Age (auto) ; 20th century warming (auto) ; Patagonia (auto)

Note: We would like to thank the SALSA scientific team for the fieldwork at Lago del Desierto in March 2005. Sabine Stahl and Benjamin Bunning are acknowledged for assistance with sampling and geochemical analyses. Thomas Frederichs and Christian Hilgenfeld (Department of Marine Geophysics, University of Bremen) kindly enabled magnetic susceptibility measurements. Tephra samples were analysed by courtesy of Peter Abbott (University of Swansea). For assistance during XRF-scanning, we thank Rita Frohlking (AWI Bremerhaven). The coring was conducted as a pilot study during a field trip in the framework of the DEKLIM project "South Argentinean Lake Sediment Archives and modelling" (SALSA, grants 01 LD 0034 and 0035) founded by the German Federal Ministry of Education and Research (BMBF). We appreciate the critical review of the manuscript and the helpful comments of Nathalie Fagel.

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Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2010

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