Element Geochemical Characteristics of Early to Middle Miocene Sediments in Core IODP U1500B from the Northern South China Sea and Implications on Paleoclimate of the Source Area
Through elemental geochemical analysis of sediments at 1262.6–1288.3 m in IODP Core U1500B from the northern South China Sea,the climate and environmental evolution history of Southwestern China during the early to middle Miocene (20–14 Ma) can be reconstructed. The analysis results of REE show that the sediments are mainly sourced from the Yunnan-Guizhou Plateau in Southwest China. The major element ratios,CIA,PIA,C values,Sr/Cu and principal component analysis jointly indicate strong chemical weathering conditions and warm-humid climate in the source area during the early to middle Miocene. The climate in Southwest China was well correlated with the global climate during 17–14 Ma,but contradicted the global cold and dry conditions before 17 Ma,possibly due to influence of the strong uplift of the Qinghai-Tibet region during the late Oligocene to early Miocene. The uplift of the plateau led to great strengthening of the South Asian monsoon compared to before,resulting in a relatively warmer and more humid climate in the Southwest China during the Early Miocene (20–17 Ma) (Although the South Asian monsoon had shown a slight weakening trend due to the global cooling during this period). During 17–14 Ma,the strengthening of the South Asian monsoon continued to affect the southwestern region of China,and at that time,the global climate was also in the middle Miocene Climatic Optimum (MCO),so the climate change trends of the two were consistent.
northern South China SeaIODP Core U1500BpaleoclimateSouth Asian monsoon
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