Southern Hemispheric Westerlies control sedimentary processes of Laguna Azul (south-eastern Patagonia, Argentina)

Multiproxy investigations of lacustrine sediments from Laguna Azul (52 °S) document multi-millennial Holocene influences of Southern Hemispheric Westerlies (SHW) on the hydroclimatic variability of south-eastern Patagonia. During the last 4000 years, this hydroclimatic variability is overprinted by centennial warm/dry periods. A cool/wet period from 11,600 to 10,100 cal. BP is succeeded by an early Holocene dry period (10,100–8300 cal. BP) with a shallow lake, strong anoxia, methanogenesis and high salinity. Between 8300 and 4000 cal. BP the influence of SHW weakened, resulting in a freshwater lake considered to be related to less arid conditions. Since 4000 cal. BP, regional temperature decreased accompanied by re-intensification of SHW reaching full strength since 3000 cal. BP. Centred around 2200, 1000 cal. BP and in the 20th century, Laguna Azul experienced century-long warm/dry spells. Between these dry periods, two pronounced moist periods are suggested to be contemporaneous to the ‘Dark Age Cold Period’ and the ‘Little Ice Age’. Different from millennial SHW variations, centennial fluctuations appear to be synchronous for South America and the Northern Hemisphere. Changes in solar activity, large volcanic eruptions and/or modulations of ocean circulation are potential triggers for this synchronicity. Fil: Zolitschka, Bernd. Universitat Bremen; Alemania Fil: Fey, Michael. Universitat Bremen; Alemania Fil: Janssen, Stephanie. Universitat zu Köln; Alemania Fil: Maidana, Nora Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina Fil: Mayr, Christoph. Universitat Technical Zu Munich; Alemania. Universitat Erlangen-Nuremberg; Alemania Fil: Wulf, Sabine. GFZ German Research Centre for Geosciences ; Alemania. University of Portsmouth; Alemania Fil: Haberzettl, Torsten. University of Greifswald; Alemania Fil: Corbella, Jorge Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Lücke, Andreas. IBG-3. Agrosphere, Institute of Bio- and Geosciences; Alemania Fil: Ohlendorf, Christian. Universitat Bremen; Alemania Fil: Schäbitz, Frank. Universitat zu Köln; Alemania