Developing geochemical proxies for a high resolution hydroclimate record in Mono Lake basin

Hydrological fluctuations of Mono Lake, a terminal closed-basin lake in the western Great Basin, are related to the regional climate fluctuations. These hydrological changes lead to variations in paleosalinity which may be recorded at a high resolution by the geochemical proxies in the lacustrine Wilson Creek Formation sediments of the Mono Lake basin. Authigenic minerals like calcite and Mg-smectite in the lacustrine sediments record the fluctuations in the lake level through the last glacial period.;During the course of this research project, I have developed leachable Li (hosted by the Mg-smectite) and other leachable ions as geochemical proxies for paleosalinity (and thus paleohydrology) in the Wilson Creek sediments. I applied a multi-pronged approach, including measurements of leachable ions. I followed these results and tested my hypothesis for their behavior by construction of empirical evaporation and mixing models using Geochemist Workbench and PHREEQC. I used this strategy to demonstrate that the freshening of Mono Lake during the last glacial period could explain the variations. These investigations in the Mono Lake basin have shown that leachable Li along with leachable ions like Ca, Mg and Sr closely follow the documented lake level based on stratigraphic and geomorphic evidence. The empirical models used to predict the geochemical evolution of Mono Lake with hydrological variations allow the accurate prediction of the behavior of authigenic mineral phases like Mg- smectite and the calcite proxy record for the paleolake level changes.