Site 1144 is located at 20°3.18´N, 117°25.14´E, at a water depth of ~2037 m, which is above the sill depth of the Bashi Strait (2600 m) (Fig. F1). Modern sea-surface temperature (SST) in the area is 28.8°C in summer and ~23.5°C in winter, and the depth of thermocline is at ~120 m (Pflaumann and Jian, 1999). Three holes were drilled to 519.19 meters composite depth (mcd), and the oldest sediment recovered is of early Pleistocene age. Sedimentation rates at this site are extremely high because of its vicinity to the Pear River mouth in the northern South China Sea (Wang, Prell, Blum, et al., 2000): 930 m/m.y. for the last 0.3 m.y. and ~390 m/m.y. between 0.3 and 1.0 Ma. With excellent 100% core recovery, this thick sediment succession is ideal for high-resolution studies of fine-scale paleoclimatic and paleoceanographic changes in the region.
The hemipelagic sediments are characterized by fine-grained clay-sized terrigenous material, quartz silt, calcareous nannofossils, and foraminifers with frequent black iron sulfide mottling and pyrite. A microtectite layer found at 386 mcd records a large-scale meteorite impact in the region at ~0.78 Ma (Glass, 1967; Zhao et al., 1999).
We conducted a postcruise study on planktonic foraminifers from cores below 300 mcd at Site 1144, aiming to quantify the abundance variations of planktonic foraminifer species and to provide evidence of high-resolution faunal responses to the mid-Pleistocene climate transition in the northern South China Sea.