| Speleothems from Chinese caves provide precisely-dated, high-resolution archives of the history of the East Asian monsoon. Research in this field has grown rapidly in recent years and has greatly improved our understanding of the climatic variability in China and the linkages to the global climate system. This thesis contributes four stalagmite delta18O and delta13C records, dated by U-series methods, from Xiangshui Cave, Yaoba Don Cave, Lianhua Cave, and Jintanwan Cave.;Lianhua Cave (109°32'45"E, 29°29'N, elevation 455 m), Hunan Province, yielded an aragonite stalagmite (A1) covering the Mid- to Late-Holocene (∼6.5 ka to present). During this period, the delta18O record shows an overall weakening of the East Asian monsoon with several distinct millennial- to decadal-scale events, including an abrupt and severe weakening of the summer monsoon around ∼3.3 ka that marks the onset of Neoglacial conditions. The expressions of these events in other Holocene stalagmites from China suggest similar regional changes with some local differences. Spectral and wavelet analyses reveal common periodicities that occur at both solar and non-solar frequencies. Variations in the delta13C record of stalagmite A1 reflect climatic influence on biological and inorganic processes. Periods of intensified summer monsoonal circulation correspond to lower delta 13C values in response to increased plant growth and microbial activity in the soil, higher drip rates, and diminished cave air ventilation.;Stalagmite J1 from Jintanwan Cave (109°32'E, 29°29'N, elevation 460 m), Hunan Province, spans the interval from ∼30 to ∼11 ka with a hiatus between ∼15 to ∼12 ka. The East Asian summer monsoon weakened and then strengthened during the Last Glacial Maximum in response to changes in northern hemisphere summer insolation and weakened during Heinrich event 1 in response to changing oceanic circulation. Although the deglacial monsoon history expressed in stalagmite J1 is incomplete because of the hiatus, the transition from the Younger Dryas to the Holocene at ∼11.5 ka is represented. The delta18O and delta13C values of this stalagmite were measured using microdrill and laser ablation sampling techniques. Comparisons between the two techniques demonstrate that laser ablation can quickly reproduce the overall trends in the microdrill data, but the microdrill data can achieve higher spatial resolution and greater precision.;Keywords: speleothem, East Asian monsoon, oxygen and carbon isotopes;Stalagmite X3 from Xiangshui Cave (110°55'E, 25°15'N, elevation 380 m), Guangxi Province and stalagmite YB1 from Yaoba Don Cave (109°50' E, 28°48' N, elevation 420 m), Hunan Province, span a portion of the last glacial period (∼51 to ∼19 ka). Millennial-scale fluctuations recorded in these stalagmites correlate with Dansgaard-Oeschger events (2-13) and Heinrich events (H2-H5), demonstrating a linkage between the Asian monsoon and atmospheric and oceanic conditions in the region of the North Atlantic. |
