Moisture changes and fluctuations of the Westerlies in Mediterranean Central Chile during the last 2000 years:: The Laguna Aculeo record (33°50′S)

The multi-proxy study of lacustrine sediments from Laguna Aculeo (33degrees50'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 and period between cal 200 BC and AD 200 and a subsequent increase in moisture after cal AD 200. Abundant elastic 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 elastic 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. (C) 2001 Elsevier Science Ltd and INQUA. All rights reserved.