Statistics of sediment mass in the South China Sea: Method and results

Abstract

Sediment mass volumes for periods since the Oligocene (E₃, N₁¹, N₁², N₁³, N₂, and Q) in the South China Sea (SCS) were calculated on the basis of geological and geophysical data including ODP borehole data. Above the pre-Oligocene base, the estimated sediment volume is 7.01×10⁶ km³ and the mass is 1.44×10¹⁶ t for the entire SCS, with an average sedimentation rate of 6.22 cm/ka and accumulation rate of 12.8 g/(cm² · ka) since the Oligocene. Most of the sediment was deposited on the continent shelf and slope, while only 5% of the total mass accumulated in the Central Basin. Sediment basins on shelf and slope occupy 34% of the entire SCS area bounded by the 2 000 m thickness contour, but receive more than 82% of the total sediment mass, indicating that sediment basins played a central role of sedimentary process in the SCS. The highest sedimentation rate and the largest mass volume occurred in the Oligocene SCS, which is quite different from global sedimentation rate patterns. Therefore, we conclude that deposition in marginal seas was primarily controlled by local tectonics.