High-resolution benthic foraminifer δ13C records in the South China Sea during the last 150 ka

High-resolution δ13C ratios of benthic foraminifer, Cibicidoides wuellerstorfi, in Core MD97-2151 from the southern South China Sea (SCS) and Core SO50-31KL from the northern SCS indicate deep-water variations in the SCS during the last 150 ka. The δ13C records of both show a general variation pattern with higher δ13C during interglacial periods than glacial periods, and rapid increases during terminations. This variation pattern resembles those of the West Pacific intermediate/deep water, the sources of the SCS deep water and the general variation of global deep water, indicating that the variation of the SCS deep water is largely controlled by global factors, such as carbon cycles and global deep-water circulation. Spectra analysis exhibits robust Milankovitch cycles in the SCS deep-water δ13C, again supporting global controls. Significant semi-precession cycles can also be seen in the spectra, implying that changes of local surface productivity also influence the SCS deep-water δ13C.