海南新英湾更新世以来物源及古环境意义OA

[Objective]Xinying Bay,Hainan province,has retained a relatively complete sedimentary record of ma-rine stratigraphy since the Pleistocene.Owing to its closure and stability,it serves as a good window to reflect the paleoenvironmental changes since the Pleistocene in the northern South China Sea.[Methods]Based on the analysis of whole rock major elements and Sr-Nd isotopes,the source of sediment material and the evolution of paleoclimate in this area since the Pleistocene were reconstructed,and the driving mechanism was discussed.[Results]The bore-hole has three sections from bottom to top.The bottom section,U1,has a relatively low εNd(0)value and a relatively high 86Sr/87Sr value.The middle section,U2,has relatively high ratios of Al/Ti,K/Ti,Fe/Ti,and Mg/Ti.The results of provenance analysis show that the sediments of the borehole come from the intermediate source area,and the U1 section contains more older sedimentary materials,and the Sr-Nd isotope ratio is similar to that of the Red river sedi-ments,whereas U2 and U3 are similar to the Cretaceous-Permian feldspar granite in Hainan Island.The paleo-environmental analysis shows that this region has experienced changes from dry cold to warm wet,and then to dry cold since the Pleistocene.[Conclusions]The sedimentary period of section U1 corresponds to the coldest period,MIS16,in the Northern Hemisphere,which combined with previous chronological studies,the dry and cold climate,and relatively low sea level,enable the clastic sediments of the Indochina continent to be transported to Xinying Bay.Then,the East Asian summer monsoon strengthened,and the climate changed from cold and dry to warm and humid.As a result,the source area of U2 was dominated by granitic rocks in Hainan Island because the sea level increased.U3 has undergone regional tectonic uplift,and the sedimentary source area is dominated by granite in the island.