The multi-proxy study of lacustrine sediments from Laguna Aculeo (33°50'S) provides detailed information about moisture changes in the lowlands of Mediterranean Central Chile during the last 2000 years. The lake lies just at the northern border of the strong Westerlies influence with dry summers and humid winters. Geochemical, sedimentological and diatom analyses provide evidence for an arid period between cal 200 BC and AD 200 and a subsequent increase in moisture after cal AD 200. Abundant clastic layers in the core represent flood events. Periods with a higher frequency of flood events indicate an increased intensity of the Westerlies, more winter frontal system activity and possibly ENSO-related variability, probably comparable to modern conditions in Mediterranean Central Chile. Periods of high clastic input occur around cal AD 200-400, 500-700, especially around cal AD 1300-1700, and around AD 1850-1998. During the last 50 years, at least eight flood events were detected, correlating mainly with El Nino years. A very short drier period also occurred in the late 1960s. In recent decades, human impact has resulted in a eutrophication of the lake.
Bibliographical noteFunding Information:
This study was funded by the Swiss National Science Foundation (NSF 21-50854.97 and 20.56908.99). We would like to thank Daniel Ariztegui, Platt Bradbury, Erika Gobet, Martin Grosjean, Philip Jeker, Urs Krähenbühl, Moritz Lehmann, and Frank Oldfield for scientific support and fruitful discussions, and Andreas Brodbeck for the cartography. We are grateful to Caspar Ammann for his critical editorial support. We thank Willi Tanner, Martin Grosjean, Christoph Lucas, Julieta Massaferro and Rodrigo Villa for help during fieldwork and Fernando Escobar (DGA, Chile) for providing part of the climate data. We also appreciate the critical and helpful reviews by Vera Markgraf and Florence Sylvestre.
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