Geochemical characteristics and paleoenvironmental significance of the major elements in the sediments of Core TS6 from the southern part of Southwest Taiwan Basin of the South China Sea

Geochemical characteristics of major elements from the column sample TS6 in the southern part of Southwest Taiwan Basin, together with the grain size and AMS¹⁴C dating data are studied for both the changes in depositional environment and climate of the area since the last deglaciation. Vertical distribution of the major elements shows that Mn is autogenous and abundantly enriched near the surface of sediments, suggesting that the modern bottom water is highly oxygen-enriched. The water environmental conditions of the study area, therefore, are very beneficial for the deposition of hydrogenic ferromanganese nodules. Statistical analysis of major elements suggests that the major elements of Al, Fe, Mg, K and Ti represent the terrigenous element association. The ratios of these terrigenous elements, such as Al₂O₃/TiO₂, Fe₂O₃/TiO₂, MgO/TiO₂ and MgO/Al₂O₃, are closely related to climatic fluctuations since the last deglaciation. Two climatic cooling events are observed in the periods of 9.8 kaBP~9.4 kaBP and 6.5 kaBP~5.8 kaBP respectively, indicating that the intensity of East Asian summer monsoon was significantly weakened then. The cooling event happened during the period of 6.5 kaBP ~5.8 kaBP showed a pattern of "double peaks". The ratios of major elements further indicate that there may also be some climatic cooling events around 18.5 kaBP and 15.8 kaBP in the last deglaciation, and the cold event at 15.8 kaBP should correspond to the event of Heinrich 1.