Tufa-based reconstructions of Huasco Basin Lake levels

Abstract

This thesis investigates the Salar del Huasco (northern Chile) as a potential site for palaeohydrological reconstructions of precipitation over the South American Altiplano, and presents a preliminary lake level chronology for the last deglaciation. Resolving the timings of past lake level highstands in the South American Altiplano will ultimately provide better understanding of what climate events force the South American Summer Monsoon (SASM) further south. Better insight into the forcing mechanisms of the SASM will improve our understanding of monsoon systems, and can be applied to refine global climate models of the region. To create this lake level chronology, tufa samples deposited at different elevations within the Salar del Huasco were dated using U/Th disequilibrium dating, and stable isotope measurements were applied to examine the past hydrology of the basin. The Salar del Huasco was found to have remained a hydrologically closed basin during highstand events, meaning lake level variations within the basin are purely driven by local precipitation-evaporation balances. Furthermore, the preliminary lake level chronology broadly agrees with the timings suggested by other palaeohydrological studies from the region, and provides support for a currently controversial lake level highstand between 120-100 ka. These results imply that the Salar del Huasco accurately reflects SASM-forced lake level histories, and should be studied further.