Areal distribution of Late Holocene sediment proxies controlled by lake internal dynamics, Laguna Potrok Aike, Argentina

KASTNER, S.; OHLENDORF, C.; HABERZETTL, T.; LÜCKE, A.; MAIDANA, N. I.; MAYR, C.; SCHÄBITZ, F.; ZOLITSCHKA, B.

San Carlos de Bariloche, Argentina.

Congreso; VII Southern Connection Congress; 2010

Southern Connection

Situated in the dry steppe of Patagonia the maar Laguna Potrok Aike is a key terrestrial climate archive on the southern hemisphere. Interdisciplinary multi-proxy sediment studies document the sensitivity of this lacustrine archive to palaeoenvironmental variability and a close relation of the lakes hydrological budget to fluctuations of the Southern Hemispheric Westerlies. The spatial distribution of late Holocene sediments was analysed by a dense grid of gravity cores. Using XRF and magnetic susceptibility scanning data all cores were correlated and linked to an existing age model. Then multi-proxy analyses of six selected time intervals covering distinct lake level stages back to AD 1380 were conducted. The dataset was used to create distribution maps by point kriging. In addition to catchment characteristics, modern areal sediment distribution is strongly influenced by dominant westerly winds. This results in distinct littoral wave erosion and sediment focussing by wind-driven internal currents. The selected time slices infer modified depositional dynamics resulting from a variable lake level and changing wind patterns. Distribution patterns of the deep basin reveal intensified sediment relocation during lower lake levels and strengthened winds (~AD 1960). A homogeneous sediment distribution results from higher lake levels and weakened westerly winds (~AD 1800).