THE PALEOENVIRONMENTAL SIGNIFICANCE OF THE CHARACTER OF THE ELEMENT GEOCHEMISTRY IN THE SOUTHWESTERN SOUTH CHINA SEA SINCE LATE PLEISTOCENE

Analysis of the geochemistry and granularity has been performed on samples from core MD01-2392 at middle slope near the Mekong delta, southern South China Sea (SCS). The result indicates that the Mekong River was the main source of the MD01-2392 sediment and the source area did not change much in the past 400 ka. Variations in Ti and CaO concentrations were used to track the change of terrestrial and the biogenic carbonate contents respectively. It indicated that the content of CaCO₃ follows the "Atlantic cyclicities" of low values during glacials and high values during interglacials. In contrast, the content of terrigenous sediment shows an opposite glacial-interglacial variation pattern. The results indicate that the CaCO₃ cycle at this SCS locality was strongly influenced by terrigenous dilution. Ti-normalized ratios and the behavior of the elements during chemical weathering reflect stronger chemical weathering in interglacials than in glacials. This indicates that warm and wet climate occurs in the source area. The Ti-normalized ratios of the REE are influence by the percentage of the terrestrial materials.