A MOLECULAR ISOTOPIC AND MULTI-PROXY PALEOHYDROLOGICAL RECONSTRUCTION FROM ZACA LAKE, CALIFORNIA OVER THREE MILLENNIA: INITIAL RESULTS

Zaca Lake presents a unique opportunity to capture a quasi-annual resolution lacustrine record of southern Californian climate. In July 2009 we collected two 9m cores from the center of the lake that span 3kyr, with supporting information coming from 2 littoral cores, a core from the ephemeral lake below the main lake and monitoring of modern limnological and climatic conditions. In the theme of this session, we present our holistic, multi-proxy approach to reconstructing paleoclimate and paleolimnology. The main thrust of our analyses is to conduct compound specific hydrogen isotopic measurements at cm-scale resolution in order to reconstruct the changes in the precipitation/evaporation balance and the isotopic composition of precipitation, elucidating the atmospheric circulation mechanisms for hydrological change. This biomarker isotopic approach is combined with a multi-proxy suite of analyses including grain size and elemental data at cm-resolution to enable robust paleolimnological and paleoclimatic interpretations, and to constrain event stratigraphy, including the flood history. In addition we use mm-scale x-ray fluorescence scanning to maximize the temporal information from these laminated sediments, capturing quasi-annual resolution records of Ti abundance, evidence for terrigenous inputs. Initial results will be reported at the meeting.