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David McGee. Tweedy, Ruth Rosegrant. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences s-cl--- 2020-09-03T17:49:27Z 2020-09-03T17:49:27Z 2020 2020 https://hdl.handle.net/1721.1/127148 1191839187 Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, May, 2020 Cataloged from the official PDF of thesis. Includes bibliographical references (pages 55-58). 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. by Ruth Rosegrant Tweedy. S.B. S.B. Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences 58 pages eng Massachusetts Institute of Technology MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided. http://dspace.mit.edu/handle/1721.1/7582 Earth, Atmospheric, and Planetary Sciences. Tufa-based reconstructions of Huasco Basin Lake levels Thesis application/pdf 2020-09-03T17:49:27Z Publication Bachelor EAPS unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="cfa5b18e-ed14-43b0-9925-a1bf9465606a"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Tufa-based reconstructions of Huasco Basin Lake levels</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2020</PublicationDate> <Authors> <Author> <DisplayName>Tweedy, Ruth Rosegrant.</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Earth, Atmospheric, and Planetary Sciences.</Keyword> <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.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>