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dc.contributor.authorPartin, Judson Wileyen_US
dc.date.accessioned2008-06-10T20:36:53Z
dc.date.available2008-06-10T20:36:53Z
dc.date.issued2008-04-01en_US
dc.identifier.urihttp://hdl.handle.net/1853/22556
dc.description.abstractThe West Pacific Warm Pool (WPWP) plays an important role in the global heat budget and global hydrologic cycle, so knowledge about its past variability would improve our understanding of global climate. Variations in WPWP precipitation are most notable during El Niño-Southern Oscillation events, when climate changes in the tropical Pacific impact rainfall not only in the WPWP, but around the globe. The stalagmite records presented in this dissertation provide centennial-to-millennial-scale constraints of WPWP precipitation during three distinct climatic periods: the Last Glacial Maximum (LGM), the last deglaciation, and the Holocene. In Chapter 2, the methodologies associated with the generation of U/Th-based absolute ages for the stalagmites are presented. In the final age models for the stalagmites, dates younger than 11,000 years have absolute errors of ±400 years or less, and dates older than 11,000 years have a relative error of ±2%. Stalagmite-specific 230Th/232Th ratios, calculated using isochrons, are used to correct for the presence of unsupported 230Th in a stalagmite at the time of formation. Hiatuses in the record are identified using a combination of optical properties, high 232Th concentrations, and extrapolation from adjacent U/Th dates. In Chapter 3, stalagmite oxygen isotopic composition (d18O) records from N. Borneo are presented which reveal millennial-scale rainfall changes that occurred in response to changes in global climate boundary conditions, radiative forcing, and abrupt climate changes. The stalagmite d18O records detect little change in inferred precipitation between the LGM and the present, although significant uncertainties are associated with the impact of the Sunda Shelf on rainfall d18O during the LGM. A millennial-scale drying in N. Borneo, inferred from an increase in stalagmite d18O, peaks at ~16.5ka coeval with timing of Heinrich event 1, possibly related to a southward movement of the Intertropical Convergence Zone (ITCZ). An inferred precipitation maximum (stalagmite d18O minimum) during the mid-Holocene in N. Borneo supports La Niña-like conditions and/or a southward migration of the ITCZ over the course of the Holocene as likely mechanisms for the observed millennial-scale trends. In Chapter 4, stalagmite Mg/Ca, Sr/Ca, and d13C records reflect hydrologic changes in the overlying karst system that are linked to a combination of rainfall variability and cave micro-environmental effects. Dripwater and stalagmite geochemistry suggest that prior calcite precipitation is a mechanism which alters dripwater geochemistry in slow, stalagmite-forming drips in N. Borneo. Stalagmite Mg/Ca ratios and d13C records suggest that the LGM climate in N. Borneo was drier and that ecosystem carbon cycling may have responded to the drier conditions. Large amplitude decadal- to centennial-scale variability in stalagmite Mg/Ca, Sr/Ca and d13C during the deglaciation may be linked to deglacial abrupt climate change events.en_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectPaleoclimateen_US
dc.subjectENSOen_US
dc.subjectHoloceneen_US
dc.subjectLast Glacial Maximumen_US
dc.subjectWest Pacific Warm Poolen_US
dc.subjectDeglaciationen_US
dc.subjectAbrupt climate changeen_US
dc.subjectSpeleothemen_US
dc.subjectGeochemistryen_US
dc.subjectTrace metal ratioen_US
dc.subjectStalagmiteen_US
dc.subjectCarbon isotopesen_US
dc.subjectOxygen isotopesen_US
dc.subjectUranium-thorium datingen_US
dc.subject.lcshHydrologic cycle
dc.subject.lcshClimatology
dc.subject.lcshClimatic changes
dc.subject.lcshStalactites and stalagmites
dc.subject.lcshPrecipitation (Meteorology)
dc.subject.lcshGeology, Stratigraphic
dc.subject.lcshPaleoclimatology
dc.titleStalagmite reconstructions of western tropical pacific climate from the last glacial maximum to presenten_US
dc.typeDissertationen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentEarth and Atmospheric Sciencesen_US
dc.description.advisorCommittee Chair: Cobb, Kim M; Committee Member: Aharon, Paul; Committee Member: Ingall, Ellery; Committee Member: Lynch-Stieglitz, Jean; Committee Member: Webster, Peter Jen_US


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