冲绳海槽北部基底构造特征

利用最新的重磁数据对冲绳海槽北部的基底构造进行了推断解释.研究表明，在海槽内部主要发育两条火山带，一条为著名的吐噶喇火山链，由一系列活动的或休眠的串珠状展布的活火山岛构成；另一条沿海槽中央张裂轴分布，主要由孤立的海底火山构成.冲绳海槽的基底具有沿东西向凹－凸－凹相间的构造格局，深度在1 km~8 km之间变化，受吐葛喇断裂带的北部断裂F1的作用，第三系基底构造发生了显著变化，说明吐葛喇断裂带的北部断裂F1是一条构造转换带.莫霍面为一北北东向的向东倾伏的幔坡，地壳厚度由21 km减至18 km.

The basement tectonics in north of the Okinawa trough

The basement tectonics in the north of Okinawa Trough was deduced using the latest gravity and magnetic data.The results indicate that there are two igneous rock zones in Okinawa Trough.One is the famous Tokara volcanic belt which makes of a series of active or resting volcanoes like a string of beads.The other igneous rock zone distributes in the spreading axis of the center of trough,which mainly makes of isolated benthonic volcanoes.The basement tectonics in the north of Okinawa Trough is concaved-protruded- concaved in EW direction.The depth of the basement varies from 1 km to 8 km.Under the effect of the north fault F1 of Tokara fracture belt,the basement tectonics varies a lot.This indicates that the fault F1 is a transformed fault zone.Moho is a east inclined surface tending to NNE.,and the thickness of the crust reduces from 21 km to 18 km.