Analysis on the Formation of the Thin Continental Crust in the South China Sea

The thin continental crust in the South China Sea belonging to the margin sea is distributed at the sides of the Center basin. The correct understanding of the formation causes of the thin crust is a key link to the tectonic evolution of the South China Sea. Based on the calculation of the crust stretching factors and the interpretation of the crust uplift and erosion since Mesozoic, the formation of the thin continental crust in the South China Sea is considered to be not only by stretch and extension but also by uplift and erosion from Late-Mesozoic to End-Oligocene resulting in the exposure of acid-intrusive rocks on ground and the heterogeneous thickness of the upper crust at thin continental crust. In the South China Sea, the strata in Eocene with both land-marine transitive facies and marine facies deposited at the south margin, but only continental facies deposited at the north margin, which suggests that the basins developed at the north and south continental margins of the South China Sea were of different depositional environments with uplift zones between them. All of the geological characteristics mentioned above indicate that there was ever an occasion of overlap occurring time between the uplift event and extension event. The formation of the thin continental crust in the South China Sea was not only by stretching and extension but also by both extension and erosion. It will reach a wrong conclusion that the extension extent of thin continental crust is still calculated by the formula of the total crustal extensive factor at an area where long-time uplift and erosion once occurred.