The diversity and levels of bioproductivity in the equatorial Pacific Ocean are among the highest found anywhere on the globe today. The area is thought to be responsible for 50% of new global bioproduction (Chavez and Barber, 1987). Such high levels of bioproduction consequently lead to a high rate of pelagic sedimentation that may have the potential for providing high-resolution records of temporal and spatial change in the equatorial Pacific Ocean. The high level of primary production within the upwelling region of the area is likely due to the abundance of phytoplankton. Diatoms are among the most abundant aquatic organisms, and the resistance of their siliceous frustules to dissolution has led to their preservation over large areas of the ocean floor.
The South China Sea (SCS), situated in the southwestern Pacific Ocean region, is one of the largest marginal seas in the world and has been of increasing interest to marine scientists. Previous work in the SCS mainly focused on the changes in surface water paleotemperature, paleosalinities, paleoprodution, and carbonate cycles in the late Quaternary (Wang and Wang, 1990; Wang et al., 1995; Chen et al., 2000; Tu et al., 2000). A few diatom studies were related to surface sediment diatoms in the SCS (Wang et al. 1988; Yu and Zhang, 1989; Lu, 1999, 2001). In addition, a few studies dealt with diatom biostratigraphy and the paleoenvironment, especially in the southern SCS. In this report, we present the diatom biostratigraphy and proxies for paleoupwelling at Site 1143.