南海西缘断裂带的地球物理特征及其构造地质意义

Geophysical features of the western-edge fault zone of the South China Sea and its significance of tectonic geology

南海西缘断裂带以8°N为界分为南北两段。主断裂是一条形成于中生代的基底断裂,在新生代为持续活动的断裂带,并控制了沿断裂带及其邻近分布的新生代盆地的发育。断裂带内无磁性的高密度岩体属于印支期或燕山第1,4,5期之中的某一期花岗岩侵入体,它很可能是燕山晚期的产物。该断裂带的基底断裂在万安盆地的延伸段位于盆地中部;万安盆地东缘断裂带是新生代以来受盆地中部基底断裂右行走滑的扭张应力作用,在盆地东部边缘引发断陷而形成的。

The western-edge fault zone of the South China Sea is divided into the southern and northern parts about at 8°N. The main fault of the western-edge fault zone is originated from the Mesozoic basement fault, continuously developed into the Cenozoic, and has dominated the growth of Cenozoic basins nearby it. The non-magnetic, high-density igneous rocks in the fault zone belong to granite intrusion of one period among the Indosinian or Yanshanian I, IV and V phases, which is most possibly at the end of the Yans- hanian. The main fault of the western-edge fault zone extends through the middle of the Wan＇ an Basin, and its right-lateral strike-slip activities have induced the marginal depressing and rifting at the east of the Wan＇ an Basin.