南海成因:岩石圈破裂与俯冲带相互作用新认识

South China Seabasin opening:Lithospheric rifting and interactionwith surroundingsubduction zones

南海深部计划与国际大洋钻探航次取得了一系列创新进展与重大突破:1)发现南海陆缘岩石圈减薄之初未出现地幔蛇纹岩出露,且岩浆迅速出现;2)新提出南海不是"小大西洋",而是"板缘张裂"盆地,与经典的大西洋型"板内张裂"陆缘模式不同;3)揭示南海受到俯冲带的强烈控制,提出俯冲诱发地幔上涌并影响南海岩浆活动。

The South China Sea(SCS) is the largest marginal sea in the western Pacific Ocean. Significant breakthroughs have been made in the SCS researches, especially through the South China Sea Deep Initiative and International Ocean Discovery Program(IODP). One of the surprising discoveries is that the expected mantle serpentinites at the IODP drill sites are not found at the northern SCS continental margin;instead, the magma is found to erupt rapidly, indicating the significant magmatism at the SCS soon after the continental rifting and probably due to the strong influence of surrounding subduction zones. Thus, the SCS might be regarded as a new type of rift basin of"plate-edge rifting", different from the classic Atlantic type of"intra-plate rifting". It is also suggested that the subduction-induced mantle upwelling is likely to play an important role in the magmatism of the SCS.