Ocean Drilling Program, United States

During Leg 184 we will core hemipelagic sediments in the South China Sea (SCS) to determine the evolution and variability of the East Asian monsoon during the late Cenozoic. Of the six primary proposed drill sites, five are located on the northern continental slope of the SCS in water depths ranging from 1265 m to 3190 m. In the southern SCS, one site will be located on the southern margin in 2830 m water depth. The major goals of Leg 184 are to improve our knowledge about the variability of monsoonal climates, including millennial to possibly centennial variability from high-sedimentation rate records (SCS-1), orbital-scale variability from records at all SCS sites, and tectonic-scale variability from late Cenozoic sections (Sites SCS-4 and 5). The records from the SCS will be used to establish the links between the East Asian and Indian monsoons and to evaluate mechanisms of internal (climate system feedbacks) and external (orbital and tectonic) climate forcing. We seek to test a suite of hypotheses that link uplift of the Himalayan and Tibetan Plateau complex (HTC) to both the intensification of the Asian monsoon and late Cenozoic global cooling. The proposed drilling program in the SCS will enable comparison of the Chinese terrestrial record with the marine records of monsoonal climates and hence provide an additional regional constraint on the scenarios for monsoon evolution.