南海西缘新生代沉积盆地形成动力学探讨  

FORMATION MECHANISM FOR BASINS ON THE WESTERN MARGIN OF SOUTH CHINA SEA

作　　者：吴世敏[1] 丘学林[1] 周蒂[1] 

机构地区：[1]中国科学院边缘海地质重点实验室,中国科学院南海海洋研究所,广东广州510301

出　　处：《大地构造与成矿学》2005年第3期346-353,共8页Geotectonica et Metallogenia

基　　金：国家重点基础发展规划课题(G2000046702);"十五"科研院所社会公益研究专项项目(编号2001DIA50041);科学院重要方向项目(KZCX2-SW-117)资助.

摘　　要：通过对南海西缘新生代沉积盆地伸展作用、沉降、构造变形等特征分析,检查印支地块多条近北西向走滑断裂时间、幅度等特征以及与盆地之间联系,结果表明印度—欧亚碰撞引起的逃逸作用与南海西缘新生代盆地没有直接的成因联系;两个与俯冲有关的不同扩张机制与南海西缘新生代盆地有成因联系,即(1)太平洋板块在古新世到始新世的滚动后退,太平洋—欧亚板块汇聚速率的降低驱使这些盆地产生初始伸展作用;(2)渐新世到中中新世古南海南倾俯冲板块的拖曳力,进一步驱使这些盆地的伸展及接着的南海扩张。After examining the relationship among the Three Pagodas/Mae Ping/Red River fault systems and the sedimentary basins along the west margin of South China Sea, the authors pointed out that the extrusion model cannot explain the formation of the basins. The late Cretaceous - Eocene onset of extension in South China offshore basins coincides with a decrease in Pacific-Eurasia convergence rates, which vary from 120-140 m/a to 40mm/a. The decrease in absolute convergence rate may have allowed slab rollback to initiate extension along the China offshore including the west margin of South China Sea. Since Oligocene, Australian plate has driven the Philippine Sea plate northward between the Eurasia and Pacific plates. The effect of the Philippine Sea plate would have removed the extensional force derived from rollback of Pacific plate. Uplift and erosion of China offshore basin and spread ridge as well as southward jumping of South China Sea reflect the decreasing influence on South China Sea of the Pacific plate subduction. It seems that the widespread Oligocene rifting across the west margin of South China Sea and the continued spreading of the South China Sea require a different extensional driving force. Slab pull force from southward subduction of a proto-South China Sea beneath Kalimantan may be a good choice. A great number of evidences support southward subduction beneath Kalimantan during the Oligocene to Mid - Miocene and the forces associated with this event would have the potential to generate the rifting of the basins and continued opening of South China Sea. Therefore, two forces were related to the subduction systems, i. e. , the rollback of the Pacific plate and the traction force of the proto-South China Seal southward subduction led to the extension of the basins along the west margin of South China Sea.

关 键 词：南海 沉积盆地 形成机制 动力学 

分 类 号：P541[天文地球—构造地质学]