Pre-site survey for potential new ICDP sites in southern Patagonia (Argentina)

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We propose to carry out an airgun seismic survey for the planned ICDP coring site (scheduled for the GLAD200 system) at the 1 to 2 Ma old maar Laguna Potrok Aike and a pre-site survey of so far unstudied crater lakes in the volcanic area of the Meseta Cerro Colorado, both in southern Patagonia (Argentina). Previous and ongoing investigations at Laguna Potrok Aike promise a long and undisturbed sediment record that might span several glacial/interglacial cycles unidentified for midlatitudes of the southern hemisphere until now. Based on a 3.5 kHz seismic survey a horizontally layered body of pelagic sediments with a thickness exceeding 30-40 m was recognized. Short and piston coring of up to 17m of sediment provide data about Holocene variabilities of the moisture balance - data which is of great value for the prevailing water-dependent sheep farming economy. The maximum sediment thickness is ultimately needed for proposing a new ICDP drilling site and will be achieved by airgun seismic. To optimize the use of financial resources we will use this field trip also for a pre-site survey for bathymetry, physical and chemical limnology, modern pollen and diatoms and surface sediments in the Meseta Cerro Colorado to perhaps come up with a second lake suitable as ICDP coring site thus generating a north-south transect.