Spatio-temporal distribution pattern of magmatic rocks and mechanism in the South China Sea and adjacent areas

Magmatism in the South China Sea has been active for long. According to the evolutionary stage of the crust and the difference in the intensity and type of the magmatism, combined with the isotopic age data from magmatic rocks, the magmatic activities in the South China Sea and its adjacent areas can be divided into eight stages, i.e. the pre-Luliang, Luliang, Jinning, Caledonian, Hercynian, Indosinian, Yanshanian and Himalayan stages. Magmatic rocks from pre Luliang to Himalayan period are widely distributed in the South China Sea and its surrounding areas such as Guangdong, Guangxi, the Hainan Island, the Taiwan Island, the Indochina Peninsula, the Kalimantan island and the Philippine islands. The oldest magmatic rocks, the Archean biotite granite, perilla granite and gabbro, are outcropped in the Indochina Peninsula; while the latest modern magmatic rocks occur both on land and in the sea. Volcanic eruption remains active up to present. The region of the South China Sea is dominated by the Yanshanian intermediate-acid intrusive magmatic rocks, which are mainly distributed on the continental margin of the South China Sea, especially in the north and southwest. In the Himalayan period, however, the region is dominated by strong basic and ultrabasic magmatic activities, mainly consisting of basaltic rocks. In general, the magmatic activity in sea area is lagged behind that on land.