东海的地壳结构特征

The crustal structure character of East China Sea

介绍了国内外有关东海地壳结构特征的调查研究状况,并利用前人大量的调查研究成果,根据自西向东地壳速度结构的差异,将东海海区划分为东海陆架区、冲绳海槽区、琉球岛弧-海沟区三部分。东海陆架区主要由沉积盖层(速度为5.8～5.9km/s)、基底层(速度为6.0～6.3km/s)和下地壳层(速度为6.8～7.6km/s)三个速度层组成,属于典型的大陆型地壳。冲绳海槽则位于大陆地壳和大洋地壳的过渡地带,它仍然具有大陆地壳的结构特征,并无洋壳的形成,但在海槽的轴部地壳已经减薄。琉球岛弧-海沟区的地壳结构总的来说属于过渡型地壳,但在海沟靠洋一侧已属于大洋型地壳,而从琉球海沟往东的西北菲律宾海盆,就完全属于典型的大洋地壳。

This paper presents actuality of investigation and study of the crustal structure characters of East China Sea at home and abroad. Based on the lots of investigation and study achievements and the difference of the crustal velocity structure from west to east, East China Sea is divided into three parts such as East China Sea shelf zone, Okinawa Trough zone and the Ryukyu arc-trench zone. East China Sea shelf zone mostly has three velocity layers, such as the sediment blanket layer (the velocity is 5.8～5.9 km/s), the basal layer(the velocity is 6.0～6.3 km/s),and the lower crustal layer(the velocity is 6.8～7.6 km/s).So this zone belongs to the typical continental crust. The Okinawa Trough zone is located in the transitional belt between the continental crust and the oceanic crust. It still has the structure characters of the continental crust, and no any formation of the oceanic crust, but its crust of the central trough has thined. The Ryukyu arc-trench zone is belonging to the transition type crust as a whole, but the side of the trench is already belonging to the oceanic crust. And the northwest Philippines Basin to the east of the Ryukyu trench absolutely belongs to the typical oceanic crust.