CONICET | Buscador de Institutos y Recursos Humanos

Abstract Lakes are key sites for studying paleoclimatic aspects. In the case of Llancanelo Lake Mendoza, Argentina), it is an endoreic, highly saline water body located in the southern extreme of a tectonic basin known as Central or Huarpes Depression which extends between the Andes Cordillera, San Rafael Block and Payenia Volcanic Field in southern Mendoza Province, western Argentina. The lake evolved as a major regional depocenter during the Pliocene-Quaternary, hence it contains important thicknesses of intra and extra basinal clastic and evaporitic sediments mainly dominated by volcaniclastic products. Main conditioning factors in the lake evolution were arc and backarc volcanism as well as climatic changes. Geomorphological and sedimentary evidences support the hypothesis that the lake was in past times larger than in present days. The present contribution supplies new information aimed at defining the lake´s former extension, in this case on the western lacustrine plain. Geophysical surveys based on electromagnetic induction (EMI) and geoelectricity (Multielectrode Resistivity Meter), as well as short drillings, were performed along a 8 km long transect perpendicular to the lake west shoreline. The combined analysis of geophysical and sedimentological information, supported by microfaunistic studies, lab analysis and petrographic/EDAX determinations, allowed establishing the presence, in the subsoil, of a lacustrine sequence at least 30 m thick mainly composed of volcaniclastic sediments. The lake evolution towards its present environmental characteristics, under the influence of volcanic eruptions and climatic changes, allowed intercalations -in the lacustrine sedimentary sequences- of ash layers, evaporites, soils, eolian and swamp deposits.

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