东海陆架盆地“反转-改造”构造迁移演化特征——以西湖凹陷边缘构造为例

The Characteristics of “Inverse-transform” Tectonic Migration Evolution of the East China Sea Shelf Basin ——By Taking the Marginal Structure of Xihu Sag for Exammple

在东海陆架盆地西湖凹陷边缘与周边构造单元交汇部位研究基础上,确定了平湖运动和花港运动分别是盆地构造迁移从西部坳陷带跃迁到东部坳陷带、从东部坳陷带跃迁到冲绳海槽盆地的关键运动时刻。西湖凹陷边缘带构造交汇部位T02、T04界面附近均存在东侧沉降、西侧相对隆升的"跷跷板"特征,显示出先反转抬升,后改造沉降的"反转-改造"模式,分别是平湖运动和花港运动的反映。在2期关键构造运动的影响下,盆地结构特征具有显著自西向东迁移特征:在垂向上,新生代以来的主要构造运动先后在盆地东、西部坳陷带奠定了裂陷、拗陷-反转构造层垂向叠置的构造格局;在横向上,新生代以来的主要构造运动奠定了东海陆架盆地、钓鱼岛隆褶带和冲绳海槽盆地三坳两隆的构造格局,主要构造活动自西向东迁移,盆地结构自西向东依次变新,该迁移特征与同期太平洋板块的后退式俯冲有关。

On the basis of analyzing the structural relationship on the intersection of Xihu Sag and nearby structural unit in the East China Sea Shelf Basin,it was considered that Pinghu movement(T04)and Huagang movement(T02)were the key movement periods of the two tectonic migration,the first tectonic migration was from the West Depression Belt to the East Depression Belt,and the second was from the East Depression Belt to Okinawa Trough Basin.In the east and west edge of Xihu Sag,the intersections with other tectonic units,the T02 and T04interface showed the characters of the east subsidence,and the west relative uplift,it was called a'see-saw'effect.It was the reflection of the two stages of tectonic movements.Influenced by the two tectonic movements,the basin structure presented significant characteristics of migration from the west to the east.Vertically,the main tectonic movement established the vertical superposition of rifting,depression-inversion structural layer since the Cenozoic.Horizontally,the main tectonic movement established the tectonic pattern of'three-depressions and two-uplifts'in the East China Sea Shelf Basin,the Diaoyu Island Uplift Belt and the Okinawa Trough Basin.The main tectonic movement has the characters of migration from the west to the east,and the new changes take place in the basin structure from the west to the east.The tectonic movement migration are related to the contemporaneous retreated subduction of Pacific Plate.