Paleoclimatic Studies of Closed-Basin Lakes in Great Basin of the Western U.S.

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The Quaternary geology of the Great Basin of the Western U.S. has much to offer in term of ice age climate records on land in mid-latitudes. Previous works have shown that the continental climate may have responded to astronomical (orbital) forcing in a manner that could be quite different from the high-latitude glacial response recorded in marine sediments. However, the data base for land-based records is rather meager relative to that for the oceanic realm and a rigorous comparison between the two records may hold a key to our understanding of Pleistocene climates. The objective of this project is to reconstruct the paleoclimate variations and water balance of the Western Great Basin during the past 35-40 thousand years. The reconstruction will take advantage of some recent important developments in isotopic techniques and in time stratigraphic work on sediments of the Mono and Owens Lakes. These developments enable us to quantitatively assess the paleoprecipitation/evaporation records in unprecedented detail. The isotopic tools to be used are 10Be/9Be ratios, U-series disequilibrium, and stable isotopes 818O and 813C.