163-G 1.3

Reconstructing past climatic changes from lacustrine deposits

Paleoclimate analyses of lacustrine sediments has provided essential insights into decadal to millennial-scale climate variability and its driving mechanisms. Lake basins are ideal sediment traps that continuously record environmental and climatic evolution. New analytical approaches now even allow for deciphering the timing and dynamics of abrupt climate changes and extreme hydrometeorological events causing short-term catchment runoff at seasonal resolution. The project aims at investigating sediment records of presently saline lakes in the Altiplano-Puna plateau. The Puna region is promising for reconstructing past variations in moisture availability at regional scales because of the very strong gradient in precipitation over short distances. This project, will apply identical analytical procedures to two lake sites in locations with significant differences in present-day precipitation. The main scientific goals and questions to be addressed include (1) testing previous ideas of wetter conditions during times of insolation maxima in January driven by variations in the Earth’s orbital parameters; (2) investigating both wetter and drier millennialscale intervals with respect to centennial and decadal-scale oscillations in moisture availability; (3) testing if the Younger Dryas cold period is reflected by wet or dry conditions in NW Argentina; and (4) testing the hypothesis that changes in climatic boundary conditions can cause changing frequencies of extreme meteorological events. To achieve these goals, we will first conduct a thorough site survey of several lake basins for coring in the Salta region. Main criteria for site selection are differences in precipitation regimes, basin morphology and type of sediment infill. Coring two lake basins is planed to be conducted in fall 2016 using the GFZ Niederreither system. Sediment analyses include sedimentological and micro-facies analyses on thin sections, high resolution (200 micron) micro-XRF scanning, organic and inorganic carbon determination, AMS-C14 dating, mineralogical analyses, and stable oxygen and carbon isotope analysis on carbonates.