Sedimentological and geochemical imprint of environmental changes in late Pleistocene palaeodelta-hosting deposits, southwest of the Hainan Island (South China Sea)

摘要

The study was aimed at elucidating relationships between lithological and geochemical characteristics of sediments as indicators of sea level changes during the Late Quaternary on the eastern slope of the Yinggehai-Song Hong basin. The focus was on sediments of the late Pleistocene paleodelta formed on the shelf off the Hainan Island. Examination of two cores revealed a significant lithological and geochemical variability of the sediments, particularly in the lower segments of the delta deposits, associated with the delta front (core LDW) and with the distal part of the prodelta (core ZBW). The upper segment of the deltaic sediments in core LDW most likely represents a delta plain formed under the prevalent trend of increasing sea level. On other hand the upper segment of the deltaic sediments in core ZBW should be regarded as associated with sediments of the proximal part of the prodelta, formed when the delta front was advancing and the sea level was first rising and then stabilised. Attention was paid to the relationship between lithological and geochemical features of the sediments and the seismic profiling records, particularly with respect to the paleodelta sediment series. An attempt was also made to link and correlate the sediment series with sea level changes.